Re: [PATCH 3/3] usbgadget: add support for USB mass storage gadget

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On 15.02.21 11:27, Ahmad Fatoum wrote:
> This driver is based on the f_mass_storage drivers in Linux v5.11 and
> U-Boot v2021.01. Like with U-Boot, it's invoked with a blocking ums
> command. During this time, no other processing, except for pollers, is
> possible. The command can be aborted with ctrl+c.
> 
> The state machine to implement the mass storage gadget is quite
> extensive, so import the functionality now and delay moving the state
> machine into a poller for asynchronous operation as part of a composite
> gadget for later.

I noticed some brokenness in handling error condition.
I'll respin later this week.

> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
> ---
>  commands/Makefile                   |    1 +
>  commands/ums.c                      |   53 +
>  drivers/usb/gadget/Kconfig          |   11 +
>  drivers/usb/gadget/Makefile         |    1 +
>  drivers/usb/gadget/f_mass_storage.c | 2936 +++++++++++++++++++++++++++
>  drivers/usb/gadget/storage_common.c |  173 ++
>  drivers/usb/gadget/storage_common.h |  245 +++
>  include/scsi.h                      |   12 +
>  include/usb/mass_storage.h          |   28 +
>  include/usb/storage.h               |   87 +
>  10 files changed, 3547 insertions(+)
>  create mode 100644 commands/ums.c
>  create mode 100644 drivers/usb/gadget/f_mass_storage.c
>  create mode 100644 drivers/usb/gadget/storage_common.c
>  create mode 100644 drivers/usb/gadget/storage_common.h
>  create mode 100644 include/usb/mass_storage.h
>  create mode 100644 include/usb/storage.h
> 
> diff --git a/commands/Makefile b/commands/Makefile
> index 034c0e6383d3..a31d5c877703 100644
> --- a/commands/Makefile
> +++ b/commands/Makefile
> @@ -130,5 +130,6 @@ obj-$(CONFIG_CMD_NAND_BITFLIP)	+= nand-bitflip.o
>  obj-$(CONFIG_CMD_SEED)		+= seed.o
>  obj-$(CONFIG_CMD_IP_ROUTE_GET)  += ip-route-get.o
>  obj-$(CONFIG_CMD_UBSAN)		+= ubsan.o
> +obj-$(CONFIG_USB_GADGET_MASS_STORAGE) += ums.o
>  
>  UBSAN_SANITIZE_ubsan.o := y
> diff --git a/commands/ums.c b/commands/ums.c
> new file mode 100644
> index 000000000000..0bc2cfdf5e98
> --- /dev/null
> +++ b/commands/ums.c
> @@ -0,0 +1,53 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2011 Samsung Electronics
> + * Lukasz Majewski <l.majewski@xxxxxxxxxxx>
> + *
> + * Copyright (c) 2015, NVIDIA CORPORATION. All rights reserved.
> + */
> +
> +#include <common.h>
> +#include <command.h>
> +#include <errno.h>
> +#include <malloc.h>
> +#include <getopt.h>
> +#include <fs.h>
> +#include <xfuncs.h>
> +#include <file-list.h>
> +#include <usb/mass_storage.h>
> +#include <linux/err.h>
> +
> +static int do_usb_mass_storage(int argc, char *argv[])
> +{
> +	struct f_ums_opts opts;
> +	char *argstr;
> +	int ret;
> +
> +	if (argc != optind + 1)
> +		return COMMAND_ERROR_USAGE;
> +
> +	argstr = argv[optind];
> +
> +	opts.files = file_list_parse(argstr);
> +	if (IS_ERR(opts.files)) {
> +		ret = PTR_ERR(opts.files);
> +		goto out;
> +	}
> +
> +	ret = usb_ums_register(&opts);
> +
> +	file_list_free(opts.files);
> +out:
> +	return ret;
> +}
> +
> +BAREBOX_CMD_HELP_START(usb)
> +BAREBOX_CMD_HELP_TEXT("Turn's the USB host into a UMS (USB Mass storage) gadget")
> +BAREBOX_CMD_HELP_END
> +
> +BAREBOX_CMD_START(ums)
> +	.cmd		= do_usb_mass_storage,
> +	BAREBOX_CMD_DESC("USB mass storage gadget")
> +	BAREBOX_CMD_GROUP(CMD_GRP_MISC)
> +	BAREBOX_CMD_HELP(cmd_usb_help)
> +BAREBOX_CMD_END
> diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
> index 7e0c570914d7..90d2378b5b72 100644
> --- a/drivers/usb/gadget/Kconfig
> +++ b/drivers/usb/gadget/Kconfig
> @@ -59,4 +59,15 @@ config USB_GADGET_FASTBOOT
>  	select FILE_LIST
>  	select FASTBOOT_BASE
>  	prompt "Android Fastboot USB Gadget"
> +
> +config USB_GADGET_MASS_STORAGE
> +	bool
> +	select FILE_LIST
> +	prompt "USB Mass Storage Gadget"
> +	help
> +	  The Mass Storage Gadget acts as a USB Mass Storage disk drive.
> +	  As its storage repository it can use a regular file or a block
> +	  device. Multiple storages can be specified at once on
> +	  instantiation time.
> +
>  endif
> diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
> index 27673fcf0ef6..5ba4920c085a 100644
> --- a/drivers/usb/gadget/Makefile
> +++ b/drivers/usb/gadget/Makefile
> @@ -3,6 +3,7 @@ obj-$(CONFIG_USB_GADGET) += composite.o config.o usbstring.o epautoconf.o udc-co
>  obj-$(CONFIG_USB_GADGET_SERIAL) += u_serial.o serial.o f_serial.o f_acm.o
>  obj-$(CONFIG_USB_GADGET_DFU) += dfu.o
>  obj-$(CONFIG_USB_GADGET_FASTBOOT) += f_fastboot.o
> +obj-$(CONFIG_USB_GADGET_MASS_STORAGE) += f_mass_storage.o storage_common.o
>  obj-$(CONFIG_USB_GADGET_DRIVER_ARC) += fsl_udc.o
>  pbl-$(CONFIG_USB_GADGET_DRIVER_ARC_PBL) += fsl_udc_pbl.o
>  obj-$(CONFIG_USB_GADGET_DRIVER_AT91) += at91_udc.o
> diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
> new file mode 100644
> index 000000000000..9c0076be26d1
> --- /dev/null
> +++ b/drivers/usb/gadget/f_mass_storage.c
> @@ -0,0 +1,2936 @@
> +// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
> +/*
> + * f_mass_storage.c -- Mass Storage USB Composite Function
> + *
> + * Copyright (C) 2003-2008 Alan Stern
> + * Copyright (C) 2009 Samsung Electronics
> + *                    Author: Michal Nazarewicz <m.nazarewicz@xxxxxxxxxxx>
> + * All rights reserved.
> + */
> +
> +/*
> + * The Mass Storage Function acts as a USB Mass Storage device,
> + * appearing to the host as a disk drive or as a CD-ROM drive.  In
> + * addition to providing an example of a genuinely useful composite
> + * function for a USB device, it also illustrates a technique of
> + * double-buffering for increased throughput.
> + *
> + * Function supports multiple logical units (LUNs).  Backing storage
> + * for each LUN is provided by a regular file or a block device.
> + * Access for each LUN can be limited to read-only.  Moreover, the
> + * function can indicate that LUN is removable and/or CD-ROM.  (The
> + * later implies read-only access.)
> + *
> + * MSF is configured by specifying a fsg_config structure.  It has the
> + * following fields:
> + *
> + *	nluns		Number of LUNs function have (anywhere from 1
> + *				to FSG_MAX_LUNS which is 8).
> + *	luns		An array of LUN configuration values.  This
> + *				should be filled for each LUN that
> + *				function will include (ie. for "nluns"
> + *				LUNs).  Each element of the array has
> + *				the following fields:
> + *	->filename	The path to the backing file for the LUN.
> + *				Required if LUN is not marked as
> + *				removable.
> + *	->ro		Flag specifying access to the LUN shall be
> + *				read-only.  This is implied if CD-ROM
> + *				emulation is enabled as well as when
> + *				it was impossible to open "filename"
> + *				in R/W mode.
> + *	->removable	Flag specifying that LUN shall be indicated as
> + *				being removable.
> + *	->cdrom		Flag specifying that LUN shall be reported as
> + *				being a CD-ROM.
> + *
> + *	lun_name_format	A printf-like format for names of the LUN
> + *				devices.  This determines how the
> + *				directory in sysfs will be named.
> + *				Unless you are using several MSFs in
> + *				a single gadget (as opposed to single
> + *				MSF in many configurations) you may
> + *				leave it as NULL (in which case
> + *				"lun%d" will be used).  In the format
> + *				you can use "%d" to index LUNs for
> + *				MSF's with more than one LUN.  (Beware
> + *				that there is only one integer given
> + *				as an argument for the format and
> + *				specifying invalid format may cause
> + *				unspecified behaviour.)
> + *	thread_name	Name of the kernel thread process used by the
> + *				MSF.  You can safely set it to NULL
> + *				(in which case default "file-storage"
> + *				will be used).
> + *
> + *	vendor_name
> + *	product_name
> + *	release		Information used as a reply to INQUIRY
> + *				request.  To use default set to NULL,
> + *				NULL, 0xffff respectively.  The first
> + *				field should be 8 and the second 16
> + *				characters or less.
> + *
> + *	can_stall	Set to permit function to halt bulk endpoints.
> + *				Disabled on some USB devices known not
> + *				to work correctly.  You should set it
> + *				to true.
> + *
> + * If "removable" is not set for a LUN then a backing file must be
> + * specified.  If it is set, then NULL filename means the LUN's medium
> + * is not loaded (an empty string as "filename" in the fsg_config
> + * structure causes error).  The CD-ROM emulation includes a single
> + * data track and no audio tracks; hence there need be only one
> + * backing file per LUN.  Note also that the CD-ROM block length is
> + * set to 512 rather than the more common value 2048.
> + *
> + *
> + * MSF includes support for module parameters.  If gadget using it
> + * decides to use it, the following module parameters will be
> + * available:
> + *
> + *	file=filename[,filename...]
> + *			Names of the files or block devices used for
> + *				backing storage.
> + *	ro=b[,b...]	Default false, boolean for read-only access.
> + *	removable=b[,b...]
> + *			Default true, boolean for removable media.
> + *	cdrom=b[,b...]	Default false, boolean for whether to emulate
> + *				a CD-ROM drive.
> + *	luns=N		Default N = number of filenames, number of
> + *				LUNs to support.
> + *	stall		Default determined according to the type of
> + *				USB device controller (usually true),
> + *				boolean to permit the driver to halt
> + *				bulk endpoints.
> + *
> + * The module parameters may be prefixed with some string.  You need
> + * to consult gadget's documentation or source to verify whether it is
> + * using those module parameters and if it does what are the prefixes
> + * (look for FSG_MODULE_PARAMETERS() macro usage, what's inside it is
> + * the prefix).
> + *
> + *
> + * Requirements are modest; only a bulk-in and a bulk-out endpoint are
> + * needed.  The memory requirement amounts to two 16K buffers, size
> + * configurable by a parameter.  Support is included for both
> + * full-speed and high-speed operation.
> + *
> + * Note that the driver is slightly non-portable in that it assumes a
> + * single memory/DMA buffer will be useable for bulk-in, bulk-out, and
> + * interrupt-in endpoints.  With most device controllers this isn't an
> + * issue, but there may be some with hardware restrictions that prevent
> + * a buffer from being used by more than one endpoint.
> + *
> + *
> + * The pathnames of the backing files and the ro settings are
> + * available in the attribute files "file" and "ro" in the lun<n> (or
> + * to be more precise in a directory which name comes from
> + * "lun_name_format" option!) subdirectory of the gadget's sysfs
> + * directory.  If the "removable" option is set, writing to these
> + * files will simulate ejecting/loading the medium (writing an empty
> + * line means eject) and adjusting a write-enable tab.  Changes to the
> + * ro setting are not allowed when the medium is loaded or if CD-ROM
> + * emulation is being used.
> + *
> + * When a LUN receive an "eject" SCSI request (Start/Stop Unit),
> + * if the LUN is removable, the backing file is released to simulate
> + * ejection.
> + *
> + *
> + * This function is heavily based on "File-backed Storage Gadget" by
> + * Alan Stern which in turn is heavily based on "Gadget Zero" by David
> + * Brownell.  The driver's SCSI command interface was based on the
> + * "Information technology - Small Computer System Interface - 2"
> + * document from X3T9.2 Project 375D, Revision 10L, 7-SEP-93,
> + * available at <http://www.t10.org/ftp/t10/drafts/s2/s2-r10l.pdf>.
> + * The single exception is opcode 0x23 (READ FORMAT CAPACITIES), which
> + * was based on the "Universal Serial Bus Mass Storage Class UFI
> + * Command Specification" document, Revision 1.0, December 14, 1998,
> + * available at
> + * <http://www.usb.org/developers/devclass_docs/usbmass-ufi10.pdf>.
> + */
> +
> +/*
> + *				Driver Design
> + *
> + * The MSF is fairly straightforward.  There is a main kernel
> + * thread that handles most of the work.  Interrupt routines field
> + * callbacks from the controller driver: bulk- and interrupt-request
> + * completion notifications, endpoint-0 events, and disconnect events.
> + * Completion events are passed to the main thread by wakeup calls.  Many
> + * ep0 requests are handled at interrupt time, but SetInterface,
> + * SetConfiguration, and device reset requests are forwarded to the
> + * thread in the form of "exceptions" using SIGUSR1 signals (since they
> + * should interrupt any ongoing file I/O operations).
> + *
> + * The thread's main routine implements the standard command/data/status
> + * parts of a SCSI interaction.  It and its subroutines are full of tests
> + * for pending signals/exceptions -- all this polling is necessary since
> + * the kernel has no setjmp/longjmp equivalents.  (Maybe this is an
> + * indication that the driver really wants to be running in userspace.)
> + * An important point is that so long as the thread is alive it keeps an
> + * open reference to the backing file.  This will prevent unmounting
> + * the backing file's underlying filesystem and could cause problems
> + * during system shutdown, for example.  To prevent such problems, the
> + * thread catches INT, TERM, and KILL signals and converts them into
> + * an EXIT exception.
> + *
> + * In normal operation the main thread is started during the gadget's
> + * fsg_bind() callback and stopped during fsg_unbind().  But it can
> + * also exit when it receives a signal, and there's no point leaving
> + * the gadget running when the thread is dead.  At of this moment, MSF
> + * provides no way to deregister the gadget when thread dies -- maybe
> + * a callback functions is needed.
> + *
> + * To provide maximum throughput, the driver uses a circular pipeline of
> + * buffer heads (struct fsg_buffhd).  In principle the pipeline can be
> + * arbitrarily long; in practice the benefits don't justify having more
> + * than 2 stages (i.e., double buffering).  But it helps to think of the
> + * pipeline as being a long one.  Each buffer head contains a bulk-in and
> + * a bulk-out request pointer (since the buffer can be used for both
> + * output and input -- directions always are given from the host's
> + * point of view) as well as a pointer to the buffer and various state
> + * variables.
> + *
> + * Use of the pipeline follows a simple protocol.  There is a variable
> + * (fsg->next_buffhd_to_fill) that points to the next buffer head to use.
> + * At any time that buffer head may still be in use from an earlier
> + * request, so each buffer head has a state variable indicating whether
> + * it is EMPTY, FULL, or BUSY.  Typical use involves waiting for the
> + * buffer head to be EMPTY, filling the buffer either by file I/O or by
> + * USB I/O (during which the buffer head is BUSY), and marking the buffer
> + * head FULL when the I/O is complete.  Then the buffer will be emptied
> + * (again possibly by USB I/O, during which it is marked BUSY) and
> + * finally marked EMPTY again (possibly by a completion routine).
> + *
> + * A module parameter tells the driver to avoid stalling the bulk
> + * endpoints wherever the transport specification allows.  This is
> + * necessary for some UDCs like the SuperH, which cannot reliably clear a
> + * halt on a bulk endpoint.  However, under certain circumstances the
> + * Bulk-only specification requires a stall.  In such cases the driver
> + * will halt the endpoint and set a flag indicating that it should clear
> + * the halt in software during the next device reset.  Hopefully this
> + * will permit everything to work correctly.  Furthermore, although the
> + * specification allows the bulk-out endpoint to halt when the host sends
> + * too much data, implementing this would cause an unavoidable race.
> + * The driver will always use the "no-stall" approach for OUT transfers.
> + *
> + * One subtle point concerns sending status-stage responses for ep0
> + * requests.  Some of these requests, such as device reset, can involve
> + * interrupting an ongoing file I/O operation, which might take an
> + * arbitrarily long time.  During that delay the host might give up on
> + * the original ep0 request and issue a new one.  When that happens the
> + * driver should not notify the host about completion of the original
> + * request, as the host will no longer be waiting for it.  So the driver
> + * assigns to each ep0 request a unique tag, and it keeps track of the
> + * tag value of the request associated with a long-running exception
> + * (device-reset, interface-change, or configuration-change).  When the
> + * exception handler is finished, the status-stage response is submitted
> + * only if the current ep0 request tag is equal to the exception request
> + * tag.  Thus only the most recently received ep0 request will get a
> + * status-stage response.
> + *
> + * Warning: This driver source file is too long.  It ought to be split up
> + * into a header file plus about 3 separate .c files, to handle the details
> + * of the Gadget, USB Mass Storage, and SCSI protocols.
> + */
> +
> +/* #define VERBOSE_DEBUG */
> +/* #define DUMP_MSGS */
> +
> +#define pr_fmt(fmt) "f_ums: " fmt
> +
> +#include <common.h>
> +#include <unistd.h>
> +#include <linux/stat.h>
> +#include <linux/wait.h>
> +#include <fcntl.h>
> +#include <file-list.h>
> +#include <dma.h>
> +#include <linux/bug.h>
> +#include <linux/rwsem.h>
> +#include <linux/pagemap.h>
> +#include <disks.h>
> +#include <scsi.h>
> +
> +#include <linux/err.h>
> +#include <usb/mass_storage.h>
> +
> +#include <asm/unaligned.h>
> +#include <linux/bitops.h>
> +#include <usb/gadget.h>
> +#include <usb/composite.h>
> +#include <linux/bitmap.h>
> +
> +/*------------------------------------------------------------------------*/
> +
> +#define FSG_DRIVER_DESC	"ums"
> +#define UMS_NAME_LEN 16
> +
> +#define FSG_DRIVER_VERSION	"2012/06/5"
> +
> +static const char fsg_string_interface[] = "Mass Storage";
> +
> +#include "storage_common.h"
> +
> +/* Static strings, in UTF-8 (for simplicity we use only ASCII characters) */
> +struct usb_string		fsg_strings[] = {
> +	{FSG_STRING_INTERFACE,		fsg_string_interface},
> +	{}
> +};
> +
> +static struct usb_gadget_strings	fsg_stringtab = {
> +	.language	= 0x0409,		/* en-us */
> +	.strings	= fsg_strings,
> +};
> +
> +/*-------------------------------------------------------------------------*/
> +
> +struct completion { int done; };
> +
> +#define init_completion(x) do { (x)->done = 0; } while (0)
> +#define reinit_completion(x) init_completion(x)
> +static inline int wait_for_completion_interruptible(struct completion *x)
> +{
> +	int ret;
> +
> +	while (!x->done) {
> +		ret = ctrlc();
> +		if (ret)
> +			return -ERESTARTSYS;
> +	}
> +
> +	return 0;
> +}
> +#define complete_and_exit(...) return 0
> +
> +static inline void complete(struct completion *x)
> +{
> +	x->done = 1;
> +}
> +
> +struct task_struct {
> +	int (*threadfn)(void *);
> +	void *arg;
> +};
> +
> +static struct task_struct *kthread_run(int (*threadfn)(void *), void *arg,
> +					  const char *name)
> +{
> +	struct task_struct *task;
> +
> +	task = xmalloc(sizeof(*task));
> +	task->threadfn = threadfn;
> +	task->arg = arg;
> +
> +	return task;
> +}
> +
> +#define free_kthread_struct(t) free(t)
> +
> +#define poll() thread_task->threadfn(thread_task->arg)
> +
> +#define wait_event(queue, cond)	do { poll(); } while (!(cond))
> +#define wake_up(...)		do {} while (0)
> +
> +struct task_struct	*thread_task;
> +
> +/*-------------------------------------------------------------------------*/
> +
> +struct kref {int x; };
> +
> +struct fsg_dev;
> +
> +static struct file_list *ums_files;
> +
> +static struct usb_device_descriptor ums_dev_descriptor = {
> +	.bLength		= USB_DT_DEVICE_SIZE,
> +	.bDescriptorType	= USB_DT_DEVICE,
> +	.bcdUSB			= __constant_cpu_to_le16(0x0200),
> +	.bDeviceClass		= USB_CLASS_PER_INTERFACE,
> +	.bNumConfigurations	= 1,
> +};
> +
> +/* Data shared by all the FSG instances. */
> +struct fsg_common {
> +	struct usb_gadget	*gadget;
> +	struct fsg_dev		*fsg, *new_fsg;
> +
> +	wait_queue_head_t	fsg_wait;
> +	struct usb_ep		*ep0;		/* Copy of gadget->ep0 */
> +	struct usb_request	*ep0req;	/* Copy of cdev->req */
> +	unsigned int		ep0_req_tag;
> +
> +	struct fsg_buffhd	*next_buffhd_to_fill;
> +	struct fsg_buffhd	*next_buffhd_to_drain;
> +	struct fsg_buffhd	buffhds[FSG_NUM_BUFFERS];
> +
> +	int			cmnd_size;
> +	u8			cmnd[MAX_COMMAND_SIZE];
> +
> +	unsigned int		nluns;
> +	unsigned int		lun;
> +	struct fsg_lun          luns[FSG_MAX_LUNS];
> +
> +	unsigned int		bulk_out_maxpacket;
> +	enum fsg_state		state;		/* For exception handling */
> +	unsigned int		exception_req_tag;
> +
> +	enum data_direction	data_dir;
> +	u32			data_size;
> +	u32			data_size_from_cmnd;
> +	u32			tag;
> +	u32			residue;
> +	u32			usb_amount_left;
> +
> +	unsigned int		can_stall:1;
> +	unsigned int		free_storage_on_release:1;
> +	unsigned int		phase_error:1;
> +	unsigned int		short_packet_received:1;
> +	unsigned int		bad_lun_okay:1;
> +	unsigned int		running:1;
> +
> +	struct completion	thread_wakeup_needed;
> +	struct completion	thread_notifier;
> +	bool			shutdown;
> +
> +	/* Callback functions. */
> +	const struct fsg_operations	*ops;
> +	/* Gadget's private data. */
> +	void			*private_data;
> +
> +	const char *vendor_name;		/*  8 characters or less */
> +	const char *product_name;		/* 16 characters or less */
> +	u16 release;
> +
> +	/* Vendor (8 chars), product (16 chars), release (4
> +	 * hexadecimal digits) and NUL byte */
> +	char inquiry_string[8 + 16 + 4 + 1];
> +
> +	struct kref		ref;
> +};
> +
> +struct fsg_config {
> +	unsigned nluns;
> +	struct fsg_lun_config {
> +		const char *filename;
> +		char ro;
> +		char removable;
> +		char cdrom;
> +		char nofua;
> +	} luns[FSG_MAX_LUNS];
> +
> +	/* Callback functions. */
> +	const struct fsg_operations     *ops;
> +	/* Gadget's private data. */
> +	void			*private_data;
> +
> +	const char *vendor_name;		/*  8 characters or less */
> +	const char *product_name;		/* 16 characters or less */
> +
> +	char			can_stall;
> +};
> +
> +struct fsg_dev {
> +	struct usb_function	function;
> +	struct usb_gadget	*gadget;	/* Copy of cdev->gadget */
> +	struct fsg_common	*common;
> +
> +	u16			interface_number;
> +
> +	unsigned int		bulk_in_enabled:1;
> +	unsigned int		bulk_out_enabled:1;
> +
> +	unsigned long		atomic_bitflags;
> +#define IGNORE_BULK_OUT		0
> +
> +	struct usb_ep		*bulk_in;
> +	struct usb_ep		*bulk_out;
> +};
> +
> +
> +static inline int __fsg_is_set(struct fsg_common *common,
> +			       const char *func, unsigned line)
> +{
> +	if (common->fsg)
> +		return 1;
> +	ERROR(common, "common->fsg is NULL in %s at %u\n", func, line);
> +	WARN_ON(1);
> +
> +	return 0;
> +}
> +
> +#define fsg_is_set(common) likely(__fsg_is_set(common, __func__, __LINE__))
> +
> +
> +static inline struct fsg_dev *fsg_from_func(struct usb_function *f)
> +{
> +	return container_of(f, struct fsg_dev, function);
> +}
> +
> +static inline struct f_ums_opts *
> +fsg_opts_from_func_inst(const struct usb_function_instance *fi)
> +{
> +	return container_of(fi, struct f_ums_opts, func_inst);
> +}
> +
> +typedef void (*fsg_routine_t)(struct fsg_dev *);
> +
> +static int exception_in_progress(struct fsg_common *common)
> +{
> +	return common->state > FSG_STATE_IDLE;
> +}
> +
> +/* Make bulk-out requests be divisible by the maxpacket size */
> +static void set_bulk_out_req_length(struct fsg_common *common,
> +		struct fsg_buffhd *bh, unsigned int length)
> +{
> +	unsigned int	rem;
> +
> +	bh->bulk_out_intended_length = length;
> +	rem = length % common->bulk_out_maxpacket;
> +	if (rem > 0)
> +		length += common->bulk_out_maxpacket - rem;
> +	bh->outreq->length = length;
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static struct f_ums_opts ums[14]; // FIXME
> +static int ums_count;
> +
> +static int fsg_set_halt(struct fsg_dev *fsg, struct usb_ep *ep)
> +{
> +	const char	*name;
> +
> +	if (ep == fsg->bulk_in)
> +		name = "bulk-in";
> +	else if (ep == fsg->bulk_out)
> +		name = "bulk-out";
> +	else
> +		name = ep->name;
> +	DBG(fsg, "%s set halt\n", name);
> +	return usb_ep_set_halt(ep);
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +/* These routines may be called in process context or in_irq */
> +
> +/* Caller must hold fsg->lock */
> +static void wakeup_thread(struct fsg_common *common)
> +{
> +	complete(&common->thread_wakeup_needed);
> +}
> +
> +static void report_exception(const char *prefix, enum fsg_state state)
> +{
> +	const char *msg = "<unknown>";
> +	switch (state) {
> +	/* This one isn't used anywhere */
> +	case FSG_STATE_COMMAND_PHASE:
> +		msg = "Command Phase";
> +		break;
> +	case FSG_STATE_DATA_PHASE:
> +		msg = "Data Phase";
> +		break;
> +	case FSG_STATE_STATUS_PHASE:
> +		msg = "Status Phase";
> +		break;
> +
> +	case FSG_STATE_IDLE:
> +		msg = "Idle";
> +		break;
> +	case FSG_STATE_ABORT_BULK_OUT:
> +		msg = "abort bulk out";
> +		break;
> +	case FSG_STATE_RESET:
> +		msg = "reset";
> +		break;
> +	case FSG_STATE_INTERFACE_CHANGE:
> +		msg = "interface change";
> +		break;
> +	case FSG_STATE_CONFIG_CHANGE:
> +		msg = "config change";
> +		break;
> +	case FSG_STATE_DISCONNECT:
> +		msg = "disconnect";
> +		break;
> +	case FSG_STATE_EXIT:
> +		msg = "exit";
> +		break;
> +	case FSG_STATE_TERMINATED:
> +		msg = "terminated";
> +		break;
> +	}
> +
> +	pr_debug("%s: %s\n", prefix, msg);
> +}
> +
> +static void raise_exception(struct fsg_common *common, enum fsg_state new_state)
> +{
> +	/* Do nothing if a higher-priority exception is already in progress.
> +	 * If a lower-or-equal priority exception is in progress, preempt it
> +	 * and notify the main thread by sending it a signal. */
> +	if (common->state <= new_state) {
> +		report_exception("raising (preempted)", new_state);
> +		common->exception_req_tag = common->ep0_req_tag;
> +		common->state = new_state;
> +		wakeup_thread(common);
> +	}
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int ep0_queue(struct fsg_common *common)
> +{
> +	int	rc;
> +
> +	rc = usb_ep_queue(common->ep0, common->ep0req);
> +	common->ep0->driver_data = common;
> +	if (rc != 0 && rc != -ESHUTDOWN) {
> +		/* We can't do much more than wait for a reset */
> +		WARNING(common, "error in submission: %s --> %d\n",
> +			common->ep0->name, rc);
> +	}
> +	return rc;
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +/* Bulk and interrupt endpoint completion handlers.
> + * These always run in_irq. */
> +
> +static void bulk_in_complete(struct usb_ep *ep, struct usb_request *req)
> +{
> +	struct fsg_common	*common = ep->driver_data;
> +	struct fsg_buffhd	*bh = req->context;
> +
> +	if (req->status || req->actual != req->length)
> +		DBG(common, "%s --> %d, %u/%u\n", __func__,
> +				req->status, req->actual, req->length);
> +	if (req->status == -ECONNRESET)		/* Request was cancelled */
> +		usb_ep_fifo_flush(ep);
> +
> +	/* Hold the lock while we update the request and buffer states */
> +	bh->inreq_busy = 0;
> +	bh->state = BUF_STATE_EMPTY;
> +	wakeup_thread(common);
> +}
> +
> +static void bulk_out_complete(struct usb_ep *ep, struct usb_request *req)
> +{
> +	struct fsg_common	*common = ep->driver_data;
> +	struct fsg_buffhd	*bh = req->context;
> +
> +	dump_msg(common, "bulk-out", req->buf, req->actual);
> +	if (req->status || req->actual != bh->bulk_out_intended_length)
> +		DBG(common, "%s --> %d, %u/%u\n", __func__,
> +				req->status, req->actual,
> +				bh->bulk_out_intended_length);
> +	if (req->status == -ECONNRESET)		/* Request was cancelled */
> +		usb_ep_fifo_flush(ep);
> +
> +	/* Hold the lock while we update the request and buffer states */
> +	bh->outreq_busy = 0;
> +	bh->state = BUF_STATE_FULL;
> +	wakeup_thread(common);
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +/* Ep0 class-specific handlers.  These always run in_irq. */
> +
> +static int fsg_setup(struct usb_function *f,
> +		const struct usb_ctrlrequest *ctrl)
> +{
> +	struct fsg_dev		*fsg = fsg_from_func(f);
> +	struct usb_request	*req = fsg->common->ep0req;
> +	u16			w_index = get_unaligned_le16(&ctrl->wIndex);
> +	u16			w_value = get_unaligned_le16(&ctrl->wValue);
> +	u16			w_length = get_unaligned_le16(&ctrl->wLength);
> +
> +	if (!fsg_is_set(fsg->common))
> +		return -EOPNOTSUPP;
> +
> +	switch (ctrl->bRequest) {
> +
> +	case US_BULK_RESET_REQUEST:
> +		if (ctrl->bRequestType !=
> +		    (USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE))
> +			break;
> +		if (w_index != fsg->interface_number || w_value != 0)
> +			return -EDOM;
> +
> +		/* Raise an exception to stop the current operation
> +		 * and reinitialize our state. */
> +		DBG(fsg, "bulk reset request\n");
> +		raise_exception(fsg->common, FSG_STATE_RESET);
> +		return DELAYED_STATUS;
> +
> +	case US_BULK_GET_MAX_LUN:
> +		if (ctrl->bRequestType !=
> +		    (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE))
> +			break;
> +		if (w_index != fsg->interface_number || w_value != 0)
> +			return -EDOM;
> +		VDBG(fsg, "get max LUN\n");
> +		*(u8 *) req->buf = fsg->common->nluns - 1;
> +
> +		/* Respond with data/status */
> +		req->length = min((u16)1, w_length);
> +		return ep0_queue(fsg->common);
> +	}
> +
> +	VDBG(fsg,
> +	     "unknown class-specific control req "
> +	     "%02x.%02x v%04x i%04x l%u\n",
> +	     ctrl->bRequestType, ctrl->bRequest,
> +	     get_unaligned_le16(&ctrl->wValue), w_index, w_length);
> +	return -EOPNOTSUPP;
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +/* All the following routines run in process context */
> +
> +/* Use this for bulk or interrupt transfers, not ep0 */
> +static void start_transfer(struct fsg_dev *fsg, struct usb_ep *ep,
> +		struct usb_request *req, int *pbusy,
> +		enum fsg_buffer_state *state)
> +{
> +	int	rc;
> +
> +	if (ep == fsg->bulk_in)
> +		dump_msg(fsg, "bulk-in", req->buf, req->length);
> +
> +	*pbusy = 1;
> +	*state = BUF_STATE_BUSY;
> +	rc = usb_ep_queue(ep, req);
> +	if (rc != 0) {
> +		*pbusy = 0;
> +		*state = BUF_STATE_EMPTY;
> +
> +		/* We can't do much more than wait for a reset */
> +
> +		/* Note: currently the net2280 driver fails zero-length
> +		 * submissions if DMA is enabled. */
> +		if (rc != -ESHUTDOWN && !(rc == -EOPNOTSUPP &&
> +						req->length == 0))
> +			WARNING(fsg, "error in submission: %s --> %d\n",
> +					ep->name, rc);
> +	}
> +}
> +
> +#define START_TRANSFER_OR(common, ep_name, req, pbusy, state)		\
> +	if (fsg_is_set(common))						\
> +		start_transfer((common)->fsg, (common)->fsg->ep_name,	\
> +			       req, pbusy, state);			\
> +	else
> +
> +#define START_TRANSFER(common, ep_name, req, pbusy, state)		\
> +	START_TRANSFER_OR(common, ep_name, req, pbusy, state) (void)0
> +
> +static int sleep_thread(struct fsg_common *common)
> +{
> +	int ret;
> +
> +	/* Wait until a signal arrives or we are woken up */
> +	ret = wait_for_completion_interruptible(&common->thread_wakeup_needed);
> +	if (ret) {
> +		/* If we run outside of a poller, this ensures we exit the loop */
> +		common->running = false;
> +		return ret;
> +	}
> +
> +	if (common->shutdown)
> +		return -ERESTARTSYS;
> +
> +	reinit_completion(&common->thread_wakeup_needed);
> +	return 0;
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int do_read(struct fsg_common *common)
> +{
> +	struct fsg_lun		*curlun = &common->luns[common->lun];
> +	u32			lba;
> +	struct fsg_buffhd	*bh;
> +	int			rc;
> +	u32			amount_left;
> +	loff_t			file_offset;
> +	unsigned int		amount;
> +	unsigned int		partial_page;
> +	ssize_t			nread;
> +
> +	/* Get the starting Logical Block Address and check that it's
> +	 * not too big */
> +	if (common->cmnd[0] == SCSI_READ6)
> +		lba = get_unaligned_be24(&common->cmnd[1]);
> +	else {
> +		lba = get_unaligned_be32(&common->cmnd[2]);
> +
> +		/* We allow DPO (Disable Page Out = don't save data in the
> +		 * cache) and FUA (Force Unit Access = don't read from the
> +		 * cache), but we don't implement them. */
> +		if ((common->cmnd[1] & ~0x18) != 0) {
> +			curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +			return -EINVAL;
> +		}
> +	}
> +	if (lba >= curlun->num_sectors) {
> +		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
> +		return -EINVAL;
> +	}
> +	file_offset = ((loff_t) lba) << 9;
> +
> +	/* Carry out the file reads */
> +	amount_left = common->data_size_from_cmnd;
> +	if (unlikely(amount_left == 0))
> +		return -EIO;		/* No default reply */
> +
> +	for (;;) {
> +		/* Wait for the next buffer to become available */
> +		bh = common->next_buffhd_to_fill;
> +		while (bh->state != BUF_STATE_EMPTY) {
> +			rc = sleep_thread(common);
> +			if (rc)
> +				return rc;
> +		}
> +
> +		/* Figure out how much we need to read:
> +		 * Try to read the remaining amount.
> +		 * But don't read more than the buffer size.
> +		 * And don't try to read past the end of the file.
> +		 * Finally, if we're not at a page boundary, don't read past
> +		 *	the next page.
> +		 * If this means reading 0 then we were asked to read past
> +		 *	the end of file. */
> +		amount = min(amount_left, FSG_BUFLEN);
> +		partial_page = file_offset & (PAGE_CACHE_SIZE - 1);
> +		if (partial_page > 0)
> +			amount = min(amount, (unsigned int) PAGE_CACHE_SIZE -
> +					partial_page);
> +
> +
> +		/* If we were asked to read past the end of file,
> +		 * end with an empty buffer. */
> +		if (amount == 0) {
> +			curlun->sense_data =
> +					SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
> +			curlun->info_valid = 1;
> +			bh->inreq->length = 0;
> +			bh->state = BUF_STATE_FULL;
> +			break;
> +		}
> +
> +		/* Perform the read */
> +		nread = pread(ums[common->lun].fd, bh->buf, amount, file_offset);
> +
> +		VLDBG(curlun, "file read %u @ %llu -> %zd\n", amount,
> +				(unsigned long long) file_offset,
> +				nread);
> +		if (nread <= 0) {
> +			const char *err = nread ? strerror(-nread) : "EOF";
> +			LDBG(curlun, "error in file read: %s\n", err);
> +			nread = 0;
> +		} else if (nread < amount) {
> +			LDBG(curlun, "partial file read: %d/%u\n",
> +					(int) nread, amount);
> +			nread -= (nread & 511);	/* Round down to a block */
> +		}
> +		file_offset  += nread;
> +		amount_left  -= nread;
> +		common->residue -= nread;
> +		bh->inreq->length = nread;
> +		bh->state = BUF_STATE_FULL;
> +
> +		/* If an error occurred, report it and its position */
> +		if (nread < amount) {
> +			curlun->sense_data = SS_UNRECOVERED_READ_ERROR;
> +			curlun->info_valid = 1;
> +			break;
> +		}
> +
> +		if (amount_left == 0)
> +			break;		/* No more left to read */
> +
> +		/* Send this buffer and go read some more */
> +		bh->inreq->zero = 0;
> +		START_TRANSFER_OR(common, bulk_in, bh->inreq,
> +			       &bh->inreq_busy, &bh->state)
> +			/* Don't know what to do if
> +			 * common->fsg is NULL */
> +			return -EIO;
> +		common->next_buffhd_to_fill = bh->next;
> +	}
> +
> +	return -EIO;		/* No default reply */
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int do_write(struct fsg_common *common)
> +{
> +	struct fsg_lun		*curlun = &common->luns[common->lun];
> +	u32			lba;
> +	struct fsg_buffhd	*bh;
> +	int			get_some_more;
> +	u32			amount_left_to_req, amount_left_to_write;
> +	loff_t			usb_offset, file_offset;
> +	unsigned int		amount;
> +	unsigned int		partial_page;
> +	ssize_t			nwritten;
> +	int			rc;
> +
> +	if (curlun->ro) {
> +		curlun->sense_data = SS_WRITE_PROTECTED;
> +		return -EINVAL;
> +	}
> +
> +	/* Get the starting Logical Block Address and check that it's
> +	 * not too big */
> +	if (common->cmnd[0] == SCSI_WRITE6)
> +		lba = get_unaligned_be24(&common->cmnd[1]);
> +	else {
> +		lba = get_unaligned_be32(&common->cmnd[2]);
> +
> +		/* We allow DPO (Disable Page Out = don't save data in the
> +		 * cache) and FUA (Force Unit Access = write directly to the
> +		 * medium).  We don't implement DPO; we implement FUA by
> +		 * performing synchronous output. */
> +		if (common->cmnd[1] & ~0x18) {
> +			curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +			return -EINVAL;
> +		}
> +	}
> +	if (lba >= curlun->num_sectors) {
> +		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
> +		return -EINVAL;
> +	}
> +
> +	/* Carry out the file writes */
> +	get_some_more = 1;
> +	file_offset = usb_offset = ((loff_t) lba) << 9;
> +	amount_left_to_req = common->data_size_from_cmnd;
> +	amount_left_to_write = common->data_size_from_cmnd;
> +
> +	while (amount_left_to_write > 0) {
> +
> +		/* Queue a request for more data from the host */
> +		bh = common->next_buffhd_to_fill;
> +		if (bh->state == BUF_STATE_EMPTY && get_some_more) {
> +
> +			/* Figure out how much we want to get:
> +			 * Try to get the remaining amount.
> +			 * But don't get more than the buffer size.
> +			 * And don't try to go past the end of the file.
> +			 * If we're not at a page boundary,
> +			 *	don't go past the next page.
> +			 * If this means getting 0, then we were asked
> +			 *	to write past the end of file.
> +			 * Finally, round down to a block boundary. */
> +			amount = min(amount_left_to_req, FSG_BUFLEN);
> +			partial_page = usb_offset & (PAGE_CACHE_SIZE - 1);
> +			if (partial_page > 0)
> +				amount = min(amount,
> +	(unsigned int) PAGE_CACHE_SIZE - partial_page);
> +
> +			if (amount == 0) {
> +				get_some_more = 0;
> +				curlun->sense_data =
> +					SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
> +				curlun->info_valid = 1;
> +				continue;
> +			}
> +			amount -= (amount & 511);
> +			if (amount == 0) {
> +
> +				/* Why were we were asked to transfer a
> +				 * partial block? */
> +				get_some_more = 0;
> +				continue;
> +			}
> +
> +			/* Get the next buffer */
> +			usb_offset += amount;
> +			common->usb_amount_left -= amount;
> +			amount_left_to_req -= amount;
> +			if (amount_left_to_req == 0)
> +				get_some_more = 0;
> +
> +			/* amount is always divisible by 512, hence by
> +			 * the bulk-out maxpacket size */
> +			bh->outreq->length = amount;
> +			bh->bulk_out_intended_length = amount;
> +			bh->outreq->short_not_ok = 1;
> +			START_TRANSFER_OR(common, bulk_out, bh->outreq,
> +					  &bh->outreq_busy, &bh->state)
> +				/* Don't know what to do if
> +				 * common->fsg is NULL */
> +				return -EIO;
> +			common->next_buffhd_to_fill = bh->next;
> +			continue;
> +		}
> +
> +		/* Write the received data to the backing file */
> +		bh = common->next_buffhd_to_drain;
> +		if (bh->state == BUF_STATE_EMPTY && !get_some_more)
> +			break;			/* We stopped early */
> +		if (bh->state == BUF_STATE_FULL) {
> +			common->next_buffhd_to_drain = bh->next;
> +			bh->state = BUF_STATE_EMPTY;
> +
> +			/* Did something go wrong with the transfer? */
> +			if (bh->outreq->status != 0) {
> +				curlun->sense_data = SS_COMMUNICATION_FAILURE;
> +				curlun->info_valid = 1;
> +				break;
> +			}
> +
> +			amount = bh->outreq->actual;
> +
> +			/* Perform the write */
> +			nwritten = pwrite(ums[common->lun].fd, bh->buf, amount, file_offset);
> +
> +			VLDBG(curlun, "file write %u @ %llu -> %zd\n", amount,
> +					(unsigned long long) file_offset,
> +					nwritten);
> +
> +			if (nwritten < 0) {
> +				LDBG(curlun, "error in file write: %pe\n", ERR_PTR(nwritten));
> +				nwritten = 0;
> +			} else if (nwritten < amount) {
> +				LDBG(curlun, "partial file write: %d/%u\n",
> +						(int) nwritten, amount);
> +				nwritten -= (nwritten & 511);
> +				/* Round down to a block */
> +			}
> +			file_offset += nwritten;
> +			amount_left_to_write -= nwritten;
> +			common->residue -= nwritten;
> +
> +			/* If an error occurred, report it and its position */
> +			if (nwritten < amount) {
> +				pr_warn("nwritten:%zd amount:%u\n", nwritten,
> +				       amount);
> +				curlun->sense_data = SS_WRITE_ERROR;
> +				curlun->info_valid = 1;
> +				break;
> +			}
> +
> +			/* Did the host decide to stop early? */
> +			if (bh->outreq->actual != bh->outreq->length) {
> +				common->short_packet_received = 1;
> +				break;
> +			}
> +			continue;
> +		}
> +
> +		/* Wait for something to happen */
> +		rc = sleep_thread(common);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	return -EIO;		/* No default reply */
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int do_synchronize_cache(struct fsg_common *common)
> +{
> +	return 0;
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int do_verify(struct fsg_common *common)
> +{
> +	struct fsg_lun		*curlun = &common->luns[common->lun];
> +	u32			lba;
> +	u32			verification_length;
> +	struct fsg_buffhd	*bh = common->next_buffhd_to_fill;
> +	loff_t			file_offset;
> +	u32			amount_left;
> +	unsigned int		amount;
> +	ssize_t			nread;
> +
> +	/* Get the starting Logical Block Address and check that it's
> +	 * not too big */
> +	lba = get_unaligned_be32(&common->cmnd[2]);
> +	if (lba >= curlun->num_sectors) {
> +		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
> +		return -EINVAL;
> +	}
> +
> +	/* We allow DPO (Disable Page Out = don't save data in the
> +	 * cache) but we don't implement it. */
> +	if (common->cmnd[1] & ~0x10) {
> +		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +		return -EINVAL;
> +	}
> +
> +	verification_length = get_unaligned_be16(&common->cmnd[7]);
> +	if (unlikely(verification_length == 0))
> +		return -EIO;		/* No default reply */
> +
> +	/* Prepare to carry out the file verify */
> +	amount_left = verification_length << 9;
> +	file_offset = ((loff_t) lba) << 9;
> +
> +	/* Write out all the dirty buffers before invalidating them */
> +
> +	/* Just try to read the requested blocks */
> +	while (amount_left > 0) {
> +
> +		/* Figure out how much we need to read:
> +		 * Try to read the remaining amount, but not more than
> +		 * the buffer size.
> +		 * And don't try to read past the end of the file.
> +		 * If this means reading 0 then we were asked to read
> +		 * past the end of file. */
> +		amount = min(amount_left, FSG_BUFLEN);
> +		if (amount == 0) {
> +			curlun->sense_data =
> +					SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
> +			curlun->info_valid = 1;
> +			break;
> +		}
> +
> +		/* Perform the read */
> +		nread = pread(ums[common->lun].fd, bh->buf, amount, file_offset);
> +
> +		VLDBG(curlun, "file read %u @ %llu -> %zd\n", amount,
> +				(unsigned long long) file_offset,
> +				nread);
> +		if (nread <= 0) {
> +			const char *err = nread ? strerror(-nread) : "EOF";
> +			LDBG(curlun, "error in file read: %s\n", err);
> +			nread = 0;
> +		} else if (nread < amount) {
> +			LDBG(curlun, "partial file verify: %d/%u\n",
> +					(int) nread, amount);
> +			nread -= (nread & 511);	/* Round down to a sector */
> +		}
> +		if (nread == 0) {
> +			curlun->sense_data = SS_UNRECOVERED_READ_ERROR;
> +			curlun->info_valid = 1;
> +			break;
> +		}
> +		file_offset += nread;
> +		amount_left -= nread;
> +	}
> +	return 0;
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int do_inquiry(struct fsg_common *common, struct fsg_buffhd *bh)
> +{
> +	struct fsg_lun *curlun = &common->luns[common->lun];
> +	static const char vendor_id[] = "Linux   ";
> +	u8	*buf = (u8 *) bh->buf;
> +
> +	if (!curlun) {		/* Unsupported LUNs are okay */
> +		common->bad_lun_okay = 1;
> +		memset(buf, 0, 36);
> +		buf[0] = 0x7f;		/* Unsupported, no device-type */
> +		buf[4] = 31;		/* Additional length */
> +		return 36;
> +	}
> +
> +	memset(buf, 0, 8);
> +	buf[0] = TYPE_DISK;
> +	buf[1] = curlun->removable ? 0x80 : 0;
> +	buf[2] = 2;		/* ANSI SCSI level 2 */
> +	buf[3] = 2;		/* SCSI-2 INQUIRY data format */
> +	buf[4] = 31;		/* Additional length */
> +				/* No special options */
> +	sprintf((char *) (buf + 8), "%-8s%-16s%04x", (char*) vendor_id ,
> +			ums[common->lun].name, (u16) 0xffff);
> +
> +	return 36;
> +}
> +
> +
> +static int do_request_sense(struct fsg_common *common, struct fsg_buffhd *bh)
> +{
> +	struct fsg_lun	*curlun = &common->luns[common->lun];
> +	u8		*buf = (u8 *) bh->buf;
> +	u32		sd, sdinfo = 0;
> +	int		valid;
> +
> +	/*
> +	 * From the SCSI-2 spec., section 7.9 (Unit attention condition):
> +	 *
> +	 * If a REQUEST SENSE command is received from an initiator
> +	 * with a pending unit attention condition (before the target
> +	 * generates the contingent allegiance condition), then the
> +	 * target shall either:
> +	 *   a) report any pending sense data and preserve the unit
> +	 *	attention condition on the logical unit, or,
> +	 *   b) report the unit attention condition, may discard any
> +	 *	pending sense data, and clear the unit attention
> +	 *	condition on the logical unit for that initiator.
> +	 *
> +	 * FSG normally uses option a); enable this code to use option b).
> +	 */
> +#if 0
> +	if (curlun && curlun->unit_attention_data != SS_NO_SENSE) {
> +		curlun->sense_data = curlun->unit_attention_data;
> +		curlun->unit_attention_data = SS_NO_SENSE;
> +	}
> +#endif
> +
> +	if (!curlun) {		/* Unsupported LUNs are okay */
> +		common->bad_lun_okay = 1;
> +		sd = SS_LOGICAL_UNIT_NOT_SUPPORTED;
> +		valid = 0;
> +	} else {
> +		sd = curlun->sense_data;
> +		valid = curlun->info_valid << 7;
> +		curlun->sense_data = SS_NO_SENSE;
> +		curlun->info_valid = 0;
> +	}
> +
> +	memset(buf, 0, 18);
> +	buf[0] = valid | 0x70;			/* Valid, current error */
> +	buf[2] = SK(sd);
> +	put_unaligned_be32(sdinfo, &buf[3]);	/* Sense information */
> +	buf[7] = 18 - 8;			/* Additional sense length */
> +	buf[12] = ASC(sd);
> +	buf[13] = ASCQ(sd);
> +	return 18;
> +}
> +
> +static int do_read_capacity(struct fsg_common *common, struct fsg_buffhd *bh)
> +{
> +	struct fsg_lun	*curlun = &common->luns[common->lun];
> +	u32		lba = get_unaligned_be32(&common->cmnd[2]);
> +	int		pmi = common->cmnd[8];
> +	u8		*buf = (u8 *) bh->buf;
> +
> +	/* Check the PMI and LBA fields */
> +	if (pmi > 1 || (pmi == 0 && lba != 0)) {
> +		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +		return -EINVAL;
> +	}
> +
> +	put_unaligned_be32(curlun->num_sectors - 1, &buf[0]);
> +						/* Max logical block */
> +	put_unaligned_be32(512, &buf[4]);	/* Block length */
> +	return 8;
> +}
> +
> +static int do_read_header(struct fsg_common *common, struct fsg_buffhd *bh)
> +{
> +	struct fsg_lun	*curlun = &common->luns[common->lun];
> +	int		msf = common->cmnd[1] & 0x02;
> +	u32		lba = get_unaligned_be32(&common->cmnd[2]);
> +	u8		*buf = (u8 *) bh->buf;
> +
> +	if (common->cmnd[1] & ~0x02) {		/* Mask away MSF */
> +		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +		return -EINVAL;
> +	}
> +	if (lba >= curlun->num_sectors) {
> +		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
> +		return -EINVAL;
> +	}
> +
> +	memset(buf, 0, 8);
> +	buf[0] = 0x01;		/* 2048 bytes of user data, rest is EC */
> +	store_cdrom_address(&buf[4], msf, lba);
> +	return 8;
> +}
> +
> +
> +static int do_read_toc(struct fsg_common *common, struct fsg_buffhd *bh)
> +{
> +	struct fsg_lun	*curlun = &common->luns[common->lun];
> +	int		msf = common->cmnd[1] & 0x02;
> +	int		start_track = common->cmnd[6];
> +	u8		*buf = (u8 *) bh->buf;
> +
> +	if ((common->cmnd[1] & ~0x02) != 0 ||	/* Mask away MSF */
> +			start_track > 1) {
> +		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +		return -EINVAL;
> +	}
> +
> +	memset(buf, 0, 20);
> +	buf[1] = (20-2);		/* TOC data length */
> +	buf[2] = 1;			/* First track number */
> +	buf[3] = 1;			/* Last track number */
> +	buf[5] = 0x16;			/* Data track, copying allowed */
> +	buf[6] = 0x01;			/* Only track is number 1 */
> +	store_cdrom_address(&buf[8], msf, 0);
> +
> +	buf[13] = 0x16;			/* Lead-out track is data */
> +	buf[14] = 0xAA;			/* Lead-out track number */
> +	store_cdrom_address(&buf[16], msf, curlun->num_sectors);
> +
> +	return 20;
> +}
> +
> +static int do_mode_sense(struct fsg_common *common, struct fsg_buffhd *bh)
> +{
> +	struct fsg_lun	*curlun = &common->luns[common->lun];
> +	int		mscmnd = common->cmnd[0];
> +	u8		*buf = (u8 *) bh->buf;
> +	u8		*buf0 = buf;
> +	int		pc, page_code;
> +	int		changeable_values, all_pages;
> +	int		valid_page = 0;
> +	int		len, limit;
> +
> +	if ((common->cmnd[1] & ~0x08) != 0) {	/* Mask away DBD */
> +		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +		return -EINVAL;
> +	}
> +	pc = common->cmnd[2] >> 6;
> +	page_code = common->cmnd[2] & 0x3f;
> +	if (pc == 3) {
> +		curlun->sense_data = SS_SAVING_PARAMETERS_NOT_SUPPORTED;
> +		return -EINVAL;
> +	}
> +	changeable_values = (pc == 1);
> +	all_pages = (page_code == 0x3f);
> +
> +	/* Write the mode parameter header.  Fixed values are: default
> +	 * medium type, no cache control (DPOFUA), and no block descriptors.
> +	 * The only variable value is the WriteProtect bit.  We will fill in
> +	 * the mode data length later. */
> +	memset(buf, 0, 8);
> +	if (mscmnd == SCSI_MODE_SEN6) {
> +		buf[2] = (curlun->ro ? 0x80 : 0x00);		/* WP, DPOFUA */
> +		buf += 4;
> +		limit = 255;
> +	} else {			/* SCSI_MODE_SEN10 */
> +		buf[3] = (curlun->ro ? 0x80 : 0x00);		/* WP, DPOFUA */
> +		buf += 8;
> +		limit = 65535;		/* Should really be FSG_BUFLEN */
> +	}
> +
> +	/* No block descriptors */
> +
> +	/* The mode pages, in numerical order.  The only page we support
> +	 * is the Caching page. */
> +	if (page_code == 0x08 || all_pages) {
> +		valid_page = 1;
> +		buf[0] = 0x08;		/* Page code */
> +		buf[1] = 10;		/* Page length */
> +		memset(buf+2, 0, 10);	/* None of the fields are changeable */
> +
> +		if (!changeable_values) {
> +			buf[2] = 0x04;	/* Write cache enable, */
> +					/* Read cache not disabled */
> +					/* No cache retention priorities */
> +			put_unaligned_be16(0xffff, &buf[4]);
> +					/* Don't disable prefetch */
> +					/* Minimum prefetch = 0 */
> +			put_unaligned_be16(0xffff, &buf[8]);
> +					/* Maximum prefetch */
> +			put_unaligned_be16(0xffff, &buf[10]);
> +					/* Maximum prefetch ceiling */
> +		}
> +		buf += 12;
> +	}
> +
> +	/* Check that a valid page was requested and the mode data length
> +	 * isn't too long. */
> +	len = buf - buf0;
> +	if (!valid_page || len > limit) {
> +		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +		return -EINVAL;
> +	}
> +
> +	/*  Store the mode data length */
> +	if (mscmnd == SCSI_MODE_SEN6)
> +		buf0[0] = len - 1;
> +	else
> +		put_unaligned_be16(len - 2, buf0);
> +	return len;
> +}
> +
> +
> +static int do_start_stop(struct fsg_common *common)
> +{
> +	struct fsg_lun	*curlun = &common->luns[common->lun];
> +
> +	if (!curlun) {
> +		return -EINVAL;
> +	} else if (!curlun->removable) {
> +		curlun->sense_data = SS_INVALID_COMMAND;
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int do_prevent_allow(struct fsg_common *common)
> +{
> +	struct fsg_lun	*curlun = &common->luns[common->lun];
> +	int		prevent;
> +
> +	if (!curlun->removable) {
> +		curlun->sense_data = SS_INVALID_COMMAND;
> +		return -EINVAL;
> +	}
> +
> +	prevent = common->cmnd[4] & 0x01;
> +	if ((common->cmnd[4] & ~0x01) != 0) {	/* Mask away Prevent */
> +		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +		return -EINVAL;
> +	}
> +
> +	if (curlun->prevent_medium_removal && !prevent)
> +		fsg_lun_fsync_sub(curlun);
> +	curlun->prevent_medium_removal = prevent;
> +	return 0;
> +}
> +
> +
> +static int do_read_format_capacities(struct fsg_common *common,
> +			struct fsg_buffhd *bh)
> +{
> +	struct fsg_lun	*curlun = &common->luns[common->lun];
> +	u8		*buf = (u8 *) bh->buf;
> +
> +	buf[0] = buf[1] = buf[2] = 0;
> +	buf[3] = 8;	/* Only the Current/Maximum Capacity Descriptor */
> +	buf += 4;
> +
> +	put_unaligned_be32(curlun->num_sectors, &buf[0]);
> +						/* Number of blocks */
> +	put_unaligned_be32(512, &buf[4]);	/* Block length */
> +	buf[4] = 0x02;				/* Current capacity */
> +	return 12;
> +}
> +
> +
> +static int do_mode_select(struct fsg_common *common, struct fsg_buffhd *bh)
> +{
> +	struct fsg_lun	*curlun = &common->luns[common->lun];
> +
> +	/* We don't support MODE SELECT */
> +	if (curlun)
> +		curlun->sense_data = SS_INVALID_COMMAND;
> +	return -EINVAL;
> +}
> +
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int halt_bulk_in_endpoint(struct fsg_dev *fsg)
> +{
> +	int	rc;
> +
> +	rc = fsg_set_halt(fsg, fsg->bulk_in);
> +	if (rc == -EAGAIN)
> +		VDBG(fsg, "delayed bulk-in endpoint halt\n");
> +	while (rc != 0) {
> +		if (rc != -EAGAIN) {
> +			WARNING(fsg, "usb_ep_set_halt -> %d\n", rc);
> +			rc = 0;
> +			break;
> +		}
> +
> +		rc = usb_ep_set_halt(fsg->bulk_in);
> +	}
> +	return rc;
> +}
> +
> +static int wedge_bulk_in_endpoint(struct fsg_dev *fsg)
> +{
> +	int	rc;
> +
> +	DBG(fsg, "bulk-in set wedge\n");
> +	rc = 0; /* usb_ep_set_wedge(fsg->bulk_in); */
> +	if (rc == -EAGAIN)
> +		VDBG(fsg, "delayed bulk-in endpoint wedge\n");
> +	while (rc != 0) {
> +		if (rc != -EAGAIN) {
> +			WARNING(fsg, "usb_ep_set_wedge -> %d\n", rc);
> +			rc = 0;
> +			break;
> +		}
> +	}
> +	return rc;
> +}
> +
> +static int pad_with_zeros(struct fsg_dev *fsg)
> +{
> +	struct fsg_buffhd	*bh = fsg->common->next_buffhd_to_fill;
> +	u32			nkeep = bh->inreq->length;
> +	u32			nsend;
> +	int			rc;
> +
> +	bh->state = BUF_STATE_EMPTY;		/* For the first iteration */
> +	fsg->common->usb_amount_left = nkeep + fsg->common->residue;
> +	while (fsg->common->usb_amount_left > 0) {
> +
> +		/* Wait for the next buffer to be free */
> +		while (bh->state != BUF_STATE_EMPTY) {
> +			rc = sleep_thread(fsg->common);
> +			if (rc)
> +				return rc;
> +		}
> +
> +		nsend = min(fsg->common->usb_amount_left, FSG_BUFLEN);
> +		memset(bh->buf + nkeep, 0, nsend - nkeep);
> +		bh->inreq->length = nsend;
> +		bh->inreq->zero = 0;
> +		start_transfer(fsg, fsg->bulk_in, bh->inreq,
> +				&bh->inreq_busy, &bh->state);
> +		bh = fsg->common->next_buffhd_to_fill = bh->next;
> +		fsg->common->usb_amount_left -= nsend;
> +		nkeep = 0;
> +	}
> +	return 0;
> +}
> +
> +static int throw_away_data(struct fsg_common *common)
> +{
> +	struct fsg_buffhd	*bh;
> +	u32			amount;
> +	int			rc;
> +
> +	for (bh = common->next_buffhd_to_drain;
> +	     bh->state != BUF_STATE_EMPTY || common->usb_amount_left > 0;
> +	     bh = common->next_buffhd_to_drain) {
> +
> +		/* Throw away the data in a filled buffer */
> +		if (bh->state == BUF_STATE_FULL) {
> +			bh->state = BUF_STATE_EMPTY;
> +			common->next_buffhd_to_drain = bh->next;
> +
> +			/* A short packet or an error ends everything */
> +			if (bh->outreq->actual != bh->outreq->length ||
> +					bh->outreq->status != 0) {
> +				raise_exception(common,
> +						FSG_STATE_ABORT_BULK_OUT);
> +				return -EPIPE;
> +			}
> +			continue;
> +		}
> +
> +		/* Try to submit another request if we need one */
> +		bh = common->next_buffhd_to_fill;
> +		if (bh->state == BUF_STATE_EMPTY
> +		 && common->usb_amount_left > 0) {
> +			amount = min(common->usb_amount_left, FSG_BUFLEN);
> +
> +			/* amount is always divisible by 512, hence by
> +			 * the bulk-out maxpacket size */
> +			bh->outreq->length = amount;
> +			bh->bulk_out_intended_length = amount;
> +			bh->outreq->short_not_ok = 1;
> +			START_TRANSFER_OR(common, bulk_out, bh->outreq,
> +					  &bh->outreq_busy, &bh->state)
> +				/* Don't know what to do if
> +				 * common->fsg is NULL */
> +				return -EIO;
> +			common->next_buffhd_to_fill = bh->next;
> +			common->usb_amount_left -= amount;
> +			continue;
> +		}
> +
> +		/* Otherwise wait for something to happen */
> +		rc = sleep_thread(common);
> +		if (rc)
> +			return rc;
> +	}
> +	return 0;
> +}
> +
> +
> +static int finish_reply(struct fsg_common *common)
> +{
> +	struct fsg_buffhd	*bh = common->next_buffhd_to_fill;
> +	int			rc = 0;
> +
> +	switch (common->data_dir) {
> +	case DATA_DIR_NONE:
> +		break;			/* Nothing to send */
> +
> +	/* If we don't know whether the host wants to read or write,
> +	 * this must be CB or CBI with an unknown command.  We mustn't
> +	 * try to send or receive any data.  So stall both bulk pipes
> +	 * if we can and wait for a reset. */
> +	case DATA_DIR_UNKNOWN:
> +		if (!common->can_stall) {
> +			/* Nothing */
> +		} else if (fsg_is_set(common)) {
> +			fsg_set_halt(common->fsg, common->fsg->bulk_out);
> +			rc = halt_bulk_in_endpoint(common->fsg);
> +		} else {
> +			/* Don't know what to do if common->fsg is NULL */
> +			rc = -EIO;
> +		}
> +		break;
> +
> +	/* All but the last buffer of data must have already been sent */
> +	case DATA_DIR_TO_HOST:
> +		if (common->data_size == 0) {
> +			/* Nothing to send */
> +
> +		/* If there's no residue, simply send the last buffer */
> +		} else if (common->residue == 0) {
> +			bh->inreq->zero = 0;
> +			START_TRANSFER_OR(common, bulk_in, bh->inreq,
> +					  &bh->inreq_busy, &bh->state)
> +				return -EIO;
> +			common->next_buffhd_to_fill = bh->next;
> +
> +		/* For Bulk-only, if we're allowed to stall then send the
> +		 * short packet and halt the bulk-in endpoint.  If we can't
> +		 * stall, pad out the remaining data with 0's. */
> +		} else if (common->can_stall) {
> +			bh->inreq->zero = 1;
> +			START_TRANSFER_OR(common, bulk_in, bh->inreq,
> +					  &bh->inreq_busy, &bh->state)
> +				/* Don't know what to do if
> +				 * common->fsg is NULL */
> +				rc = -EIO;
> +			common->next_buffhd_to_fill = bh->next;
> +			if (common->fsg)
> +				rc = halt_bulk_in_endpoint(common->fsg);
> +		} else if (fsg_is_set(common)) {
> +			rc = pad_with_zeros(common->fsg);
> +		} else {
> +			/* Don't know what to do if common->fsg is NULL */
> +			rc = -EIO;
> +		}
> +		break;
> +
> +	/* We have processed all we want from the data the host has sent.
> +	 * There may still be outstanding bulk-out requests. */
> +	case DATA_DIR_FROM_HOST:
> +		if (common->residue == 0) {
> +			/* Nothing to receive */
> +
> +		/* Did the host stop sending unexpectedly early? */
> +		} else if (common->short_packet_received) {
> +			raise_exception(common, FSG_STATE_ABORT_BULK_OUT);
> +			rc = -EPIPE;
> +
> +		/* We haven't processed all the incoming data.  Even though
> +		 * we may be allowed to stall, doing so would cause a race.
> +		 * The controller may already have ACK'ed all the remaining
> +		 * bulk-out packets, in which case the host wouldn't see a
> +		 * STALL.  Not realizing the endpoint was halted, it wouldn't
> +		 * clear the halt -- leading to problems later on. */
> +#if 0
> +		} else if (common->can_stall) {
> +			if (fsg_is_set(common))
> +				fsg_set_halt(common->fsg,
> +					     common->fsg->bulk_out);
> +			raise_exception(common, FSG_STATE_ABORT_BULK_OUT);
> +			rc = -EPIPE;
> +#endif
> +
> +		/* We can't stall.  Read in the excess data and throw it
> +		 * all away. */
> +		} else {
> +			rc = throw_away_data(common);
> +		}
> +		break;
> +	}
> +	return rc;
> +}
> +
> +
> +static int send_status(struct fsg_common *common)
> +{
> +	struct fsg_lun		*curlun = &common->luns[common->lun];
> +	struct fsg_buffhd	*bh;
> +	struct bulk_cs_wrap	*csw;
> +	int			rc;
> +	u8			status = US_BULK_STAT_OK;
> +	u32			sd, sdinfo = 0;
> +
> +	/* Wait for the next buffer to become available */
> +	bh = common->next_buffhd_to_fill;
> +	while (bh->state != BUF_STATE_EMPTY) {
> +		rc = sleep_thread(common);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	if (curlun)
> +		sd = curlun->sense_data;
> +	else if (common->bad_lun_okay)
> +		sd = SS_NO_SENSE;
> +	else
> +		sd = SS_LOGICAL_UNIT_NOT_SUPPORTED;
> +
> +	if (common->phase_error) {
> +		DBG(common, "sending phase-error status\n");
> +		status = US_BULK_STAT_PHASE;
> +		sd = SS_INVALID_COMMAND;
> +	} else if (sd != SS_NO_SENSE) {
> +		DBG(common, "sending command-failure status\n");
> +		status = US_BULK_STAT_FAIL;
> +		VDBG(common, "  sense data: SK x%02x, ASC x%02x, ASCQ x%02x;"
> +			"  info x%x\n",
> +			SK(sd), ASC(sd), ASCQ(sd), sdinfo);
> +	}
> +
> +	/* Store and send the Bulk-only CSW */
> +	csw = (void *)bh->buf;
> +
> +	csw->Signature = cpu_to_le32(US_BULK_CS_SIGN);
> +	csw->Tag = common->tag;
> +	csw->Residue = cpu_to_le32(common->residue);
> +	csw->Status = status;
> +
> +	bh->inreq->length = US_BULK_CS_WRAP_LEN;
> +	bh->inreq->zero = 0;
> +	START_TRANSFER_OR(common, bulk_in, bh->inreq,
> +			  &bh->inreq_busy, &bh->state)
> +		/* Don't know what to do if common->fsg is NULL */
> +		return -EIO;
> +
> +	common->next_buffhd_to_fill = bh->next;
> +	return 0;
> +}
> +
> +
> +/*-------------------------------------------------------------------------*/
> +
> +/* Check whether the command is properly formed and whether its data size
> + * and direction agree with the values we already have. */
> +static int check_command(struct fsg_common *common, int cmnd_size,
> +		enum data_direction data_dir, unsigned int mask,
> +		int needs_medium, const char *name)
> +{
> +	int			i;
> +	int			lun = common->cmnd[1] >> 5;
> +	static const char	dirletter[4] = {'u', 'o', 'i', 'n'};
> +	char			hdlen[20];
> +	struct fsg_lun		*curlun;
> +
> +	hdlen[0] = 0;
> +	if (common->data_dir != DATA_DIR_UNKNOWN)
> +		sprintf(hdlen, ", H%c=%u", dirletter[(int) common->data_dir],
> +				common->data_size);
> +	VDBG(common, "SCSI command: %s;  Dc=%d, D%c=%u;  Hc=%d%s\n",
> +	     name, cmnd_size, dirletter[(int) data_dir],
> +	     common->data_size_from_cmnd, common->cmnd_size, hdlen);
> +
> +	/* We can't reply at all until we know the correct data direction
> +	 * and size. */
> +	if (common->data_size_from_cmnd == 0)
> +		data_dir = DATA_DIR_NONE;
> +	if (common->data_size < common->data_size_from_cmnd) {
> +		/* Host data size < Device data size is a phase error.
> +		 * Carry out the command, but only transfer as much as
> +		 * we are allowed. */
> +		common->data_size_from_cmnd = common->data_size;
> +		common->phase_error = 1;
> +	}
> +	common->residue = common->data_size;
> +	common->usb_amount_left = common->data_size;
> +
> +	/* Conflicting data directions is a phase error */
> +	if (common->data_dir != data_dir
> +	 && common->data_size_from_cmnd > 0) {
> +		common->phase_error = 1;
> +		return -EINVAL;
> +	}
> +
> +	/* Verify the length of the command itself */
> +	if (cmnd_size != common->cmnd_size) {
> +
> +		/* Special case workaround: There are plenty of buggy SCSI
> +		 * implementations. Many have issues with cbw->Length
> +		 * field passing a wrong command size. For those cases we
> +		 * always try to work around the problem by using the length
> +		 * sent by the host side provided it is at least as large
> +		 * as the correct command length.
> +		 * Examples of such cases would be MS-Windows, which issues
> +		 * REQUEST SENSE with cbw->Length == 12 where it should
> +		 * be 6, and xbox360 issuing INQUIRY, TEST UNIT READY and
> +		 * REQUEST SENSE with cbw->Length == 10 where it should
> +		 * be 6 as well.
> +		 */
> +		if (cmnd_size <= common->cmnd_size) {
> +			DBG(common, "%s is buggy! Expected length %d "
> +			    "but we got %d\n", name,
> +			    cmnd_size, common->cmnd_size);
> +			cmnd_size = common->cmnd_size;
> +		} else {
> +			common->phase_error = 1;
> +			return -EINVAL;
> +		}
> +	}
> +
> +	/* Check that the LUN values are consistent */
> +	if (common->lun != lun)
> +		DBG(common, "using LUN %d from CBW, not LUN %d from CDB\n",
> +		    common->lun, lun);
> +
> +	/* Check the LUN */
> +	if (common->lun < common->nluns) {
> +		curlun = &common->luns[common->lun];
> +		if (common->cmnd[0] != SCSI_REQ_SENSE) {
> +			curlun->sense_data = SS_NO_SENSE;
> +			curlun->info_valid = 0;
> +		}
> +	} else {
> +		curlun = NULL;
> +		common->bad_lun_okay = 0;
> +
> +		/* INQUIRY and REQUEST SENSE commands are explicitly allowed
> +		 * to use unsupported LUNs; all others may not. */
> +		if (common->cmnd[0] != SCSI_INQUIRY &&
> +		    common->cmnd[0] != SCSI_REQ_SENSE) {
> +			DBG(common, "unsupported LUN %d\n", common->lun);
> +			return -EINVAL;
> +		}
> +	}
> +#if 0
> +	/* If a unit attention condition exists, only INQUIRY and
> +	 * REQUEST SENSE commands are allowed; anything else must fail. */
> +	if (curlun && curlun->unit_attention_data != SS_NO_SENSE &&
> +			common->cmnd[0] != SCSI_INQUIRY &&
> +			common->cmnd[0] != SCSI_REQ_SENSE) {
> +		curlun->sense_data = curlun->unit_attention_data;
> +		curlun->unit_attention_data = SS_NO_SENSE;
> +		return -EINVAL;
> +	}
> +#endif
> +	/* Check that only command bytes listed in the mask are non-zero */
> +	common->cmnd[1] &= 0x1f;			/* Mask away the LUN */
> +	for (i = 1; i < cmnd_size; ++i) {
> +		if (common->cmnd[i] && !(mask & (1 << i))) {
> +			if (curlun)
> +				curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int do_scsi_command(struct fsg_common *common)
> +{
> +	struct fsg_buffhd	*bh;
> +	int			rc;
> +	int			reply = -EINVAL;
> +	int			i;
> +	static char		unknown[16];
> +	struct fsg_lun		*curlun = &common->luns[common->lun];
> +
> +	dump_cdb(common);
> +
> +	/* Wait for the next buffer to become available for data or status */
> +	bh = common->next_buffhd_to_fill;
> +	common->next_buffhd_to_drain = bh;
> +	while (bh->state != BUF_STATE_EMPTY) {
> +		rc = sleep_thread(common);
> +		if (rc)
> +			return rc;
> +	}
> +	common->phase_error = 0;
> +	common->short_packet_received = 0;
> +
> +	down_read(&common->filesem);	/* We're using the backing file */
> +	switch (common->cmnd[0]) {
> +
> +	case SCSI_INQUIRY:
> +		common->data_size_from_cmnd = common->cmnd[4];
> +		reply = check_command(common, 6, DATA_DIR_TO_HOST,
> +				      (1<<4), 0,
> +				      "INQUIRY");
> +		if (reply == 0)
> +			reply = do_inquiry(common, bh);
> +		break;
> +
> +	case SCSI_MODE_SEL6:
> +		common->data_size_from_cmnd = common->cmnd[4];
> +		reply = check_command(common, 6, DATA_DIR_FROM_HOST,
> +				      (1<<1) | (1<<4), 0,
> +				      "MODE SELECT(6)");
> +		if (reply == 0)
> +			reply = do_mode_select(common, bh);
> +		break;
> +
> +	case SCSI_MODE_SEL10:
> +		common->data_size_from_cmnd =
> +			get_unaligned_be16(&common->cmnd[7]);
> +		reply = check_command(common, 10, DATA_DIR_FROM_HOST,
> +				      (1<<1) | (3<<7), 0,
> +				      "MODE SELECT(10)");
> +		if (reply == 0)
> +			reply = do_mode_select(common, bh);
> +		break;
> +
> +	case SCSI_MODE_SEN6:
> +		common->data_size_from_cmnd = common->cmnd[4];
> +		reply = check_command(common, 6, DATA_DIR_TO_HOST,
> +				      (1<<1) | (1<<2) | (1<<4), 0,
> +				      "MODE SENSE(6)");
> +		if (reply == 0)
> +			reply = do_mode_sense(common, bh);
> +		break;
> +
> +	case SCSI_MODE_SEN10:
> +		common->data_size_from_cmnd =
> +			get_unaligned_be16(&common->cmnd[7]);
> +		reply = check_command(common, 10, DATA_DIR_TO_HOST,
> +				      (1<<1) | (1<<2) | (3<<7), 0,
> +				      "MODE SENSE(10)");
> +		if (reply == 0)
> +			reply = do_mode_sense(common, bh);
> +		break;
> +
> +	case SCSI_MED_REMOVL:
> +		common->data_size_from_cmnd = 0;
> +		reply = check_command(common, 6, DATA_DIR_NONE,
> +				      (1<<4), 0,
> +				      "PREVENT-ALLOW MEDIUM REMOVAL");
> +		if (reply == 0)
> +			reply = do_prevent_allow(common);
> +		break;
> +
> +	case SCSI_READ6:
> +		i = common->cmnd[4];
> +		common->data_size_from_cmnd = (i == 0 ? 256 : i) << 9;
> +		reply = check_command(common, 6, DATA_DIR_TO_HOST,
> +				      (7<<1) | (1<<4), 1,
> +				      "READ(6)");
> +		if (reply == 0)
> +			reply = do_read(common);
> +		break;
> +
> +	case SCSI_READ10:
> +		common->data_size_from_cmnd =
> +				get_unaligned_be16(&common->cmnd[7]) << 9;
> +		reply = check_command(common, 10, DATA_DIR_TO_HOST,
> +				      (1<<1) | (0xf<<2) | (3<<7), 1,
> +				      "READ(10)");
> +		if (reply == 0)
> +			reply = do_read(common);
> +		break;
> +
> +	case SCSI_READ12:
> +		common->data_size_from_cmnd =
> +				get_unaligned_be32(&common->cmnd[6]) << 9;
> +		reply = check_command(common, 12, DATA_DIR_TO_HOST,
> +				      (1<<1) | (0xf<<2) | (0xf<<6), 1,
> +				      "READ(12)");
> +		if (reply == 0)
> +			reply = do_read(common);
> +		break;
> +
> +	case SCSI_RD_CAPAC:
> +		common->data_size_from_cmnd = 8;
> +		reply = check_command(common, 10, DATA_DIR_TO_HOST,
> +				      (0xf<<2) | (1<<8), 1,
> +				      "READ CAPACITY");
> +		if (reply == 0)
> +			reply = do_read_capacity(common, bh);
> +		break;
> +
> +	case SCSI_RD_HEADER:
> +		if (!common->luns[common->lun].cdrom)
> +			goto unknown_cmnd;
> +		common->data_size_from_cmnd =
> +			get_unaligned_be16(&common->cmnd[7]);
> +		reply = check_command(common, 10, DATA_DIR_TO_HOST,
> +				      (3<<7) | (0x1f<<1), 1,
> +				      "READ HEADER");
> +		if (reply == 0)
> +			reply = do_read_header(common, bh);
> +		break;
> +
> +	case SCSI_RD_TOC:
> +		if (!common->luns[common->lun].cdrom)
> +			goto unknown_cmnd;
> +		common->data_size_from_cmnd =
> +			get_unaligned_be16(&common->cmnd[7]);
> +		reply = check_command(common, 10, DATA_DIR_TO_HOST,
> +				      (7<<6) | (1<<1), 1,
> +				      "READ TOC");
> +		if (reply == 0)
> +			reply = do_read_toc(common, bh);
> +		break;
> +
> +	case SCSI_RD_FMT_CAPAC:
> +		common->data_size_from_cmnd =
> +			get_unaligned_be16(&common->cmnd[7]);
> +		reply = check_command(common, 10, DATA_DIR_TO_HOST,
> +				      (3<<7), 1,
> +				      "READ FORMAT CAPACITIES");
> +		if (reply == 0)
> +			reply = do_read_format_capacities(common, bh);
> +		break;
> +
> +	case SCSI_REQ_SENSE:
> +		common->data_size_from_cmnd = common->cmnd[4];
> +		reply = check_command(common, 6, DATA_DIR_TO_HOST,
> +				      (1<<4), 0,
> +				      "REQUEST SENSE");
> +		if (reply == 0)
> +			reply = do_request_sense(common, bh);
> +		break;
> +
> +	case SCSI_START_STP:
> +		common->data_size_from_cmnd = 0;
> +		reply = check_command(common, 6, DATA_DIR_NONE,
> +				      (1<<1) | (1<<4), 0,
> +				      "START-STOP UNIT");
> +		if (reply == 0)
> +			reply = do_start_stop(common);
> +		break;
> +
> +	case SCSI_SYNC_CACHE:
> +		common->data_size_from_cmnd = 0;
> +		reply = check_command(common, 10, DATA_DIR_NONE,
> +				      (0xf<<2) | (3<<7), 1,
> +				      "SYNCHRONIZE CACHE");
> +		if (reply == 0)
> +			reply = do_synchronize_cache(common);
> +		break;
> +
> +	case SCSI_TST_U_RDY:
> +		common->data_size_from_cmnd = 0;
> +		reply = check_command(common, 6, DATA_DIR_NONE,
> +				0, 1,
> +				"TEST UNIT READY");
> +		break;
> +
> +	/* Although optional, this command is used by MS-Windows.  We
> +	 * support a minimal version: BytChk must be 0. */
> +	case SCSI_VERIFY:
> +		common->data_size_from_cmnd = 0;
> +		reply = check_command(common, 10, DATA_DIR_NONE,
> +				      (1<<1) | (0xf<<2) | (3<<7), 1,
> +				      "VERIFY");
> +		if (reply == 0)
> +			reply = do_verify(common);
> +		break;
> +
> +	case SCSI_WRITE6:
> +		i = common->cmnd[4];
> +		common->data_size_from_cmnd = (i == 0 ? 256 : i) << 9;
> +		reply = check_command(common, 6, DATA_DIR_FROM_HOST,
> +				      (7<<1) | (1<<4), 1,
> +				      "WRITE(6)");
> +		if (reply == 0)
> +			reply = do_write(common);
> +		break;
> +
> +	case SCSI_WRITE10:
> +		common->data_size_from_cmnd =
> +				get_unaligned_be16(&common->cmnd[7]) << 9;
> +		reply = check_command(common, 10, DATA_DIR_FROM_HOST,
> +				      (1<<1) | (0xf<<2) | (3<<7), 1,
> +				      "WRITE(10)");
> +		if (reply == 0)
> +			reply = do_write(common);
> +		break;
> +
> +	case SCSI_WRITE12:
> +		common->data_size_from_cmnd =
> +				get_unaligned_be32(&common->cmnd[6]) << 9;
> +		reply = check_command(common, 12, DATA_DIR_FROM_HOST,
> +				      (1<<1) | (0xf<<2) | (0xf<<6), 1,
> +				      "WRITE(12)");
> +		if (reply == 0)
> +			reply = do_write(common);
> +		break;
> +
> +	/* Some mandatory commands that we recognize but don't implement.
> +	 * They don't mean much in this setting.  It's left as an exercise
> +	 * for anyone interested to implement RESERVE and RELEASE in terms
> +	 * of Posix locks. */
> +	case SCSI_FORMAT:
> +	case SCSI_RELEASE:
> +	case SCSI_RESERVE:
> +	case SCSI_SEND_DIAG:
> +		/* Fall through */
> +
> +	default:
> +unknown_cmnd:
> +		common->data_size_from_cmnd = 0;
> +		sprintf(unknown, "Unknown x%02x", common->cmnd[0]);
> +		reply = check_command(common, common->cmnd_size,
> +				      DATA_DIR_UNKNOWN, 0xff, 0, unknown);
> +		if (reply == 0) {
> +			curlun->sense_data = SS_INVALID_COMMAND;
> +			reply = -EINVAL;
> +		}
> +		break;
> +	}
> +	up_read(&common->filesem);
> +
> +	if (reply == -EPIPE)
> +		return -EPIPE;
> +
> +	/* Set up the single reply buffer for finish_reply() */
> +	if (reply == -EINVAL)
> +		reply = 0;		/* Error reply length */
> +	if (reply >= 0 && common->data_dir == DATA_DIR_TO_HOST) {
> +		reply = min((u32) reply, common->data_size_from_cmnd);
> +		bh->inreq->length = reply;
> +		bh->state = BUF_STATE_FULL;
> +		common->residue -= reply;
> +	}				/* Otherwise it's already set */
> +
> +	return 0;
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int received_cbw(struct fsg_dev *fsg, struct fsg_buffhd *bh)
> +{
> +	struct usb_request	*req = bh->outreq;
> +	struct bulk_cb_wrap	*cbw = req->buf;
> +	struct fsg_common	*common = fsg->common;
> +
> +	/* Was this a real packet?  Should it be ignored? */
> +	if (req->status || test_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags))
> +		return -EINVAL;
> +
> +	/* Is the CBW valid? */
> +	if (req->actual != US_BULK_CB_WRAP_LEN ||
> +			cbw->Signature != cpu_to_le32(
> +				US_BULK_CB_SIGN)) {
> +		DBG(fsg, "invalid CBW: len %u sig 0x%x\n",
> +				req->actual,
> +				le32_to_cpu(cbw->Signature));
> +
> +		/* The Bulk-only spec says we MUST stall the IN endpoint
> +		 * (6.6.1), so it's unavoidable.  It also says we must
> +		 * retain this state until the next reset, but there's
> +		 * no way to tell the controller driver it should ignore
> +		 * Clear-Feature(HALT) requests.
> +		 *
> +		 * We aren't required to halt the OUT endpoint; instead
> +		 * we can simply accept and discard any data received
> +		 * until the next reset. */
> +		wedge_bulk_in_endpoint(fsg);
> +		set_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags);
> +		return -EINVAL;
> +	}
> +
> +	/* Is the CBW meaningful? */
> +	if (cbw->Lun >= FSG_MAX_LUNS || cbw->Flags & ~US_BULK_FLAG_IN ||
> +			cbw->Length <= 0 || cbw->Length > MAX_COMMAND_SIZE) {
> +		DBG(fsg, "non-meaningful CBW: lun = %u, flags = 0x%x, "
> +				"cmdlen %u\n",
> +				cbw->Lun, cbw->Flags, cbw->Length);
> +
> +		/* We can do anything we want here, so let's stall the
> +		 * bulk pipes if we are allowed to. */
> +		if (common->can_stall) {
> +			fsg_set_halt(fsg, fsg->bulk_out);
> +			halt_bulk_in_endpoint(fsg);
> +		}
> +		return -EINVAL;
> +	}
> +
> +	/* Save the command for later */
> +	common->cmnd_size = cbw->Length;
> +	memcpy(common->cmnd, cbw->CDB, common->cmnd_size);
> +	if (cbw->Flags & US_BULK_FLAG_IN)
> +		common->data_dir = DATA_DIR_TO_HOST;
> +	else
> +		common->data_dir = DATA_DIR_FROM_HOST;
> +	common->data_size = le32_to_cpu(cbw->DataTransferLength);
> +	if (common->data_size == 0)
> +		common->data_dir = DATA_DIR_NONE;
> +	common->lun = cbw->Lun;
> +	common->tag = cbw->Tag;
> +	return 0;
> +}
> +
> +
> +static int get_next_command(struct fsg_common *common)
> +{
> +	struct fsg_buffhd	*bh;
> +	int			rc = 0;
> +
> +	/* Wait for the next buffer to become available */
> +	bh = common->next_buffhd_to_fill;
> +	while (bh->state != BUF_STATE_EMPTY) {
> +		rc = sleep_thread(common);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	/* Queue a request to read a Bulk-only CBW */
> +	set_bulk_out_req_length(common, bh, US_BULK_CB_WRAP_LEN);
> +	bh->outreq->short_not_ok = 1;
> +	START_TRANSFER_OR(common, bulk_out, bh->outreq,
> +			  &bh->outreq_busy, &bh->state)
> +		/* Don't know what to do if common->fsg is NULL */
> +		return -EIO;
> +
> +	/* We will drain the buffer in software, which means we
> +	 * can reuse it for the next filling.  No need to advance
> +	 * next_buffhd_to_fill. */
> +
> +	/* Wait for the CBW to arrive */
> +	while (bh->state != BUF_STATE_FULL) {
> +		rc = sleep_thread(common);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	rc = fsg_is_set(common) ? received_cbw(common->fsg, bh) : -EIO;
> +	bh->state = BUF_STATE_EMPTY;
> +
> +	return rc;
> +}
> +
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int enable_endpoint(struct fsg_common *common, struct usb_ep *ep)
> +{
> +	int	rc;
> +
> +	ep->driver_data = common;
> +	rc = usb_ep_enable(ep);
> +	if (rc)
> +		ERROR(common, "can't enable %s, result %d\n", ep->name, rc);
> +	return rc;
> +}
> +
> +static int alloc_request(struct fsg_common *common, struct usb_ep *ep,
> +		struct usb_request **preq)
> +{
> +	*preq = usb_ep_alloc_request(ep);
> +	if (*preq)
> +		return 0;
> +	ERROR(common, "can't allocate request for %s\n", ep->name);
> +	return -ENOMEM;
> +}
> +
> +/* Reset interface setting and re-init endpoint state (toggle etc). */
> +static int do_set_interface(struct fsg_common *common, struct fsg_dev *new_fsg)
> +{
> +	struct fsg_dev *fsg;
> +	int i, rc = 0;
> +
> +	if (common->running)
> +		DBG(common, "reset interface\n");
> +
> +reset:
> +	/* Deallocate the requests */
> +	if (common->fsg) {
> +		fsg = common->fsg;
> +
> +		for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
> +			struct fsg_buffhd *bh = &common->buffhds[i];
> +
> +			if (bh->inreq) {
> +				usb_ep_free_request(fsg->bulk_in, bh->inreq);
> +				bh->inreq = NULL;
> +			}
> +			if (bh->outreq) {
> +				usb_ep_free_request(fsg->bulk_out, bh->outreq);
> +				bh->outreq = NULL;
> +			}
> +		}
> +
> +		/* Disable the endpoints */
> +		if (fsg->bulk_in_enabled) {
> +			usb_ep_disable(fsg->bulk_in);
> +			fsg->bulk_in_enabled = 0;
> +		}
> +		if (fsg->bulk_out_enabled) {
> +			usb_ep_disable(fsg->bulk_out);
> +			fsg->bulk_out_enabled = 0;
> +		}
> +
> +		common->fsg = NULL;
> +		wake_up(&common->fsg_wait);
> +	}
> +
> +	common->running = 0;
> +	if (!new_fsg || rc)
> +		return rc;
> +
> +	common->fsg = new_fsg;
> +	fsg = common->fsg;
> +
> +	/* Enable the endpoints */
> +	fsg->bulk_in->desc = fsg_ep_desc(common->gadget,
> +					 &fsg_fs_bulk_in_desc, &fsg_hs_bulk_in_desc);
> +	rc = enable_endpoint(common, fsg->bulk_in);
> +	if (rc)
> +		goto reset;
> +	fsg->bulk_in_enabled = 1;
> +
> +	fsg->bulk_out->desc = fsg_ep_desc(common->gadget,
> +					  &fsg_fs_bulk_out_desc, &fsg_hs_bulk_out_desc);
> +	rc = enable_endpoint(common, fsg->bulk_out);
> +	if (rc)
> +		goto reset;
> +	fsg->bulk_out_enabled = 1;
> +	common->bulk_out_maxpacket = 512;
> +	clear_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags);
> +
> +	/* Allocate the requests */
> +	for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
> +		struct fsg_buffhd	*bh = &common->buffhds[i];
> +
> +		rc = alloc_request(common, fsg->bulk_in, &bh->inreq);
> +		if (rc)
> +			goto reset;
> +		rc = alloc_request(common, fsg->bulk_out, &bh->outreq);
> +		if (rc)
> +			goto reset;
> +		bh->inreq->buf = bh->outreq->buf = bh->buf;
> +		bh->inreq->context = bh->outreq->context = bh;
> +		bh->inreq->complete = bulk_in_complete;
> +		bh->outreq->complete = bulk_out_complete;
> +	}
> +
> +	common->running = 1;
> +
> +	return rc;
> +}
> +
> +
> +/****************************** ALT CONFIGS ******************************/
> +
> +
> +static int fsg_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
> +{
> +	struct fsg_dev *fsg = fsg_from_func(f);
> +	fsg->common->new_fsg = fsg;
> +	raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE);
> +	return 0;
> +}
> +
> +static void fsg_disable(struct usb_function *f)
> +{
> +	struct fsg_dev *fsg = fsg_from_func(f);
> +	fsg->common->new_fsg = NULL;
> +	raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE);
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static void handle_exception(struct fsg_common *common)
> +{
> +	int			i;
> +	struct fsg_buffhd	*bh;
> +	enum fsg_state		old_state;
> +	struct fsg_lun		*curlun;
> +	unsigned int		exception_req_tag;
> +
> +	/* Cancel all the pending transfers */
> +	if (common->fsg) {
> +		for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
> +			bh = &common->buffhds[i];
> +			if (bh->inreq_busy)
> +				usb_ep_dequeue(common->fsg->bulk_in, bh->inreq);
> +			if (bh->outreq_busy)
> +				usb_ep_dequeue(common->fsg->bulk_out,
> +					       bh->outreq);
> +		}
> +
> +		/* Wait until everything is idle */
> +		for (;;) {
> +			int num_active = 0;
> +			for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
> +				bh = &common->buffhds[i];
> +				num_active += bh->inreq_busy + bh->outreq_busy;
> +			}
> +			if (num_active == 0)
> +				break;
> +			if (sleep_thread(common))
> +				return;
> +		}
> +
> +		/* Clear out the controller's fifos */
> +		if (common->fsg->bulk_in_enabled)
> +			usb_ep_fifo_flush(common->fsg->bulk_in);
> +		if (common->fsg->bulk_out_enabled)
> +			usb_ep_fifo_flush(common->fsg->bulk_out);
> +	}
> +
> +	/* Reset the I/O buffer states and pointers, the SCSI
> +	 * state, and the exception.  Then invoke the handler. */
> +
> +	for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
> +		bh = &common->buffhds[i];
> +		bh->state = BUF_STATE_EMPTY;
> +	}
> +	common->next_buffhd_to_fill = &common->buffhds[0];
> +	common->next_buffhd_to_drain = &common->buffhds[0];
> +	exception_req_tag = common->exception_req_tag;
> +	old_state = common->state;
> +
> +	report_exception("handling", old_state);
> +
> +	if (old_state == FSG_STATE_ABORT_BULK_OUT)
> +		common->state = FSG_STATE_STATUS_PHASE;
> +	else {
> +		for (i = 0; i < common->nluns; ++i) {
> +			curlun = &common->luns[i];
> +			curlun->sense_data = SS_NO_SENSE;
> +			curlun->info_valid = 0;
> +		}
> +		common->state = FSG_STATE_IDLE;
> +	}
> +
> +	/* Carry out any extra actions required for the exception */
> +	switch (old_state) {
> +	case FSG_STATE_ABORT_BULK_OUT:
> +		send_status(common);
> +
> +		if (common->state == FSG_STATE_STATUS_PHASE)
> +			common->state = FSG_STATE_IDLE;
> +		break;
> +
> +	case FSG_STATE_RESET:
> +		/* In case we were forced against our will to halt a
> +		 * bulk endpoint, clear the halt now.  (The SuperH UDC
> +		 * requires this.) */
> +		if (!fsg_is_set(common))
> +			break;
> +		if (test_and_clear_bit(IGNORE_BULK_OUT,
> +				       &common->fsg->atomic_bitflags))
> +			usb_ep_clear_halt(common->fsg->bulk_in);
> +
> +		if (common->ep0_req_tag == exception_req_tag)
> +			ep0_queue(common);	/* Complete the status stage */
> +
> +		break;
> +
> +	case FSG_STATE_CONFIG_CHANGE:
> +		do_set_interface(common, common->new_fsg);
> +		break;
> +
> +	case FSG_STATE_EXIT:
> +	case FSG_STATE_TERMINATED:
> +		do_set_interface(common, NULL);		/* Free resources */
> +		common->state = FSG_STATE_TERMINATED;	/* Stop the thread */
> +		break;
> +
> +	case FSG_STATE_INTERFACE_CHANGE:
> +	case FSG_STATE_DISCONNECT:
> +	case FSG_STATE_COMMAND_PHASE:
> +	case FSG_STATE_DATA_PHASE:
> +	case FSG_STATE_STATUS_PHASE:
> +	case FSG_STATE_IDLE:
> +		break;
> +	}
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static int fsg_main_thread(void *common_)
> +{
> +	struct fsg_common	*common = common_;
> +	int ret = 0;
> +
> +	/* The main loop */
> +	while (common->state != FSG_STATE_TERMINATED) {
> +		if (exception_in_progress(common)) {
> +			handle_exception(common);
> +			continue;
> +		}
> +
> +		if (!common->running) {
> +			ret = sleep_thread(common);
> +			if (ret)
> +				break;
> +			continue;
> +		}
> +
> +		ret = get_next_command(common);
> +		if (ret)
> +			continue;
> +
> +		if (!exception_in_progress(common))
> +			common->state = FSG_STATE_DATA_PHASE;
> +
> +		if (do_scsi_command(common) || finish_reply(common))
> +			continue;
> +
> +		if (!exception_in_progress(common))
> +			common->state = FSG_STATE_STATUS_PHASE;
> +
> +		if (send_status(common))
> +			continue;
> +
> +		if (!exception_in_progress(common))
> +			common->state = FSG_STATE_IDLE;
> +	}
> +
> +	if (ret && ret != -ERESTARTSYS)
> +		pr_warn("%s: error %pe\n", __func__, ERR_PTR(ret));
> +
> +	complete_and_exit(&common->thread_notifier, 0);
> +}
> +
> +static void fsg_common_release(struct kref *ref);
> +
> +static struct fsg_common *fsg_common_setup(void)
> +{
> +	struct fsg_common *common;
> +
> +	/* Allocate? */
> +	common = calloc(sizeof(*common), 1);
> +	if (!common)
> +		return NULL;
> +	common->free_storage_on_release = 1;
> +
> +	init_completion(&common->thread_notifier);
> +
> +	common->ops = NULL;
> +	common->private_data = NULL;
> +
> +	return common;
> +}
> +
> +static int fsg_common_init(struct fsg_common *common,
> +			   struct usb_composite_dev *cdev)
> +{
> +	struct usb_gadget *gadget = cdev->gadget;
> +	struct file_list_entry *fentry;
> +	struct fsg_buffhd *bh;
> +	struct fsg_lun *curlun;
> +	int nluns, i, fd = -1, rc;
> +
> +	ums_count = 0;
> +
> +	common->gadget = gadget;
> +	common->ep0 = gadget->ep0;
> +	common->ep0req = cdev->req;
> +
> +	file_list_for_each_entry(ums_files, fentry) {
> +		unsigned flags = O_RDWR;
> +		struct stat st;
> +
> +		if (fentry->flags) {
> +			pr_err("flags not supported\n");
> +			return -ENOSYS;
> +		}
> +
> +		fd = open(fentry->filename, flags);
> +		if (fd < 0) {
> +			pr_err("open('%s') failed: %pe\n",
> +			       fentry->filename, ERR_PTR(fd));
> +			return fd;
> +		}
> +
> +		rc = fstat(fd, &st);
> +		if (rc < 0) {
> +			pr_err("stat('%s') failed: %pe\n",
> +			       fentry->filename, ERR_PTR(rc));
> +			goto close;
> +		}
> +
> +		if (st.st_size % SECTOR_SIZE != 0) {
> +			pr_err("exporting '%s' failed: invalid block size\n",
> +			       fentry->filename);
> +			goto close;
> +		}
> +
> +		ums[ums_count].fd = fd;
> +		ums[ums_count].num_sectors = st.st_size / SECTOR_SIZE;
> +
> +		strlcpy(ums[ums_count].name, fentry->name, sizeof(ums[ums_count].name));
> +
> +		DBG(common, "LUN %d, %s sector_count %#x\n",
> +			ums_count, fentry->name, ums[ums_count].num_sectors);
> +
> +		ums_count++;
> +	}
> +
> +	/* Find out how many LUNs there should be */
> +	nluns = ums_count;
> +	if (nluns < 1 || nluns > FSG_MAX_LUNS) {
> +		pr_warn("invalid number of LUNs: %u\n", nluns);
> +		rc = -EINVAL;
> +		goto close;
> +	}
> +
> +	/* Maybe allocate device-global string IDs, and patch descriptors */
> +	if (fsg_strings[FSG_STRING_INTERFACE].id == 0) {
> +		rc = usb_string_id(cdev);
> +		if (unlikely(rc < 0))
> +			goto error_release;
> +		fsg_strings[FSG_STRING_INTERFACE].id = rc;
> +		fsg_intf_desc.iInterface = rc;
> +	}
> +
> +	/* Create the LUNs, open their backing files, and register the
> +	 * LUN devices in sysfs. */
> +	curlun = calloc(nluns, sizeof *curlun);
> +	if (!curlun) {
> +		rc = -ENOMEM;
> +		goto error_release;
> +	}
> +	common->nluns = nluns;
> +
> +	for (i = 0; i < nluns; i++) {
> +		common->luns[i].removable = 1;
> +
> +		rc = fsg_lun_open(&common->luns[i], ums[i].num_sectors, "");
> +		if (rc)
> +			goto error_luns;
> +	}
> +	common->lun = 0;
> +
> +	/* Data buffers cyclic list */
> +	bh = common->buffhds;
> +
> +	i = FSG_NUM_BUFFERS;
> +	goto buffhds_first_it;
> +	do {
> +		bh->next = bh + 1;
> +		++bh;
> +buffhds_first_it:
> +		bh->inreq_busy = 0;
> +		bh->outreq_busy = 0;
> +		bh->buf = dma_alloc(FSG_BUFLEN);
> +		if (unlikely(!bh->buf)) {
> +			rc = -ENOMEM;
> +			goto error_release;
> +		}
> +	} while (--i);
> +	bh->next = common->buffhds;
> +
> +	snprintf(common->inquiry_string, sizeof common->inquiry_string,
> +		 "%-8s%-16s%04x",
> +		 "Linux   ",
> +		 "File-Store Gadget",
> +		 0xffff);
> +
> +	/* Some peripheral controllers are known not to be able to
> +	 * halt bulk endpoints correctly.  If one of them is present,
> +	 * disable stalls.
> +	 */
> +
> +	/* Information */
> +	DBG(common, FSG_DRIVER_DESC ", version: " FSG_DRIVER_VERSION "\n");
> +	DBG(common, "Number of LUNs=%d\n", common->nluns);
> +
> +	return 0;
> +
> +error_luns:
> +	common->nluns = i + 1;
> +error_release:
> +	common->state = FSG_STATE_TERMINATED;	/* The thread is dead */
> +	/* Call fsg_common_release() directly, ref might be not
> +	 * initialised */
> +	fsg_common_release(&common->ref);
> +close:
> +	close(fd);
> +	return rc;
> +}
> +
> +static void fsg_common_release(struct kref *ref)
> +{
> +	struct fsg_common *common = container_of(ref, struct fsg_common, ref);
> +	struct fsg_buffhd *bh;
> +	unsigned i;
> +
> +	/* If the thread isn't already dead, tell it to exit now */
> +	if (common->state != FSG_STATE_TERMINATED) {
> +		raise_exception(common, FSG_STATE_EXIT);
> +		wait_for_completion_interruptible(&common->thread_notifier);
> +		free_kthread_struct(thread_task);
> +	}
> +
> +	bh = common->buffhds;
> +	i = FSG_NUM_BUFFERS;
> +
> +	do {
> +		dma_free(bh->buf);
> +	} while (++bh, --i);
> +
> +	if (common->free_storage_on_release)
> +		kfree(common);
> +}
> +
> +
> +static void fsg_unbind(struct usb_configuration *c, struct usb_function *f)
> +{
> +	struct fsg_dev		*fsg = fsg_from_func(f);
> +	struct fsg_common	*common = fsg->common;
> +	int i;
> +
> +	DBG(fsg, "unbind\n");
> +
> +	if (fsg->common->fsg == fsg) {
> +		fsg->common->new_fsg = NULL;
> +		fsg->common->shutdown = true;
> +		raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE);
> +		wait_event(common->fsg_wait, common->fsg != fsg);
> +	}
> +
> +	for (i = 0; i < ums_count; i++)
> +		close(ums[i].fd);
> +
> +	usb_free_all_descriptors(&fsg->function);
> +
> +	ums_files = NULL;
> +}
> +
> +static int fsg_bind(struct usb_configuration *c, struct usb_function *f)
> +{
> +	struct fsg_dev		*fsg = fsg_from_func(f);
> +	struct usb_gadget	*gadget = c->cdev->gadget;
> +	int			i = -EINVAL;
> +	struct usb_ep		*ep;
> +	struct usb_descriptor_header **hs_function = NULL;
> +	struct fsg_common	*common = fsg->common;
> +
> +	if (!ums_files) {
> +		struct f_ums_opts *opts = container_of(f->fi, struct f_ums_opts, func_inst);
> +
> +		ums_files = opts->files;
> +	}
> +
> +	fsg->gadget = gadget;
> +
> +	DBG(fsg, "bind\n");
> +
> +	i = fsg_common_init(common, c->cdev);
> +	if (i)
> +		return i;
> +
> +	thread_task = kthread_run(fsg_main_thread, common, "file-storage");
> +	if (IS_ERR(thread_task))
> +		return PTR_ERR(thread_task);
> +
> +	/* New interface */
> +	i = usb_interface_id(c, f);
> +	if (i < 0)
> +		return i;
> +	fsg_intf_desc.bInterfaceNumber = i;
> +	fsg->interface_number = i;
> +
> +	/* Find all the endpoints we will use */
> +	ep = usb_ep_autoconfig(gadget, &fsg_fs_bulk_in_desc);
> +	if (!ep)
> +		goto autoconf_fail;
> +	ep->driver_data = common;	/* claim the endpoint */
> +	fsg->bulk_in = ep;
> +
> +	ep = usb_ep_autoconfig(gadget, &fsg_fs_bulk_out_desc);
> +	if (!ep)
> +		goto autoconf_fail;
> +	ep->driver_data = common;	/* claim the endpoint */
> +	fsg->bulk_out = ep;
> +
> +	if (gadget_is_dualspeed(gadget)) {
> +		/* Assume endpoint addresses are the same for both speeds */
> +		fsg_hs_bulk_in_desc.bEndpointAddress =
> +			fsg_fs_bulk_in_desc.bEndpointAddress;
> +		fsg_hs_bulk_out_desc.bEndpointAddress =
> +			fsg_fs_bulk_out_desc.bEndpointAddress;
> +		hs_function = fsg_hs_function;
> +	}
> +
> +	/* Copy descriptors */
> +	return usb_assign_descriptors(f, fsg_fs_function, hs_function, NULL);
> +
> +autoconf_fail:
> +	ERROR(fsg, "unable to autoconfigure all endpoints\n");
> +	return -ENOTSUPP;
> +}
> +
> +
> +/****************************** ADD FUNCTION ******************************/
> +
> +static struct usb_gadget_strings *fsg_strings_array[] = {
> +	&fsg_stringtab,
> +	NULL,
> +};
> +
> +static void fsg_free(struct usb_function *f)
> +{
> +	struct fsg_dev *fsg;
> +
> +	fsg = container_of(f, struct fsg_dev, function);
> +
> +	kfree(fsg);
> +}
> +
> +static struct usb_function *fsg_alloc(struct usb_function_instance *fi)
> +{
> +	struct f_ums_opts *opts = fsg_opts_from_func_inst(fi);
> +	struct fsg_common *common = opts->common;
> +	struct fsg_dev *fsg;
> +
> +	fsg = kzalloc(sizeof(*fsg), GFP_KERNEL);
> +	if (!fsg)
> +		return ERR_PTR(-ENOMEM);
> +
> +	fsg->function.name = FSG_DRIVER_DESC;
> +	fsg->function.strings = fsg_strings_array;
> +	/* descriptors are per-instance copies */
> +	fsg->function.bind = fsg_bind;
> +	fsg->function.set_alt = fsg_set_alt;
> +	fsg->function.setup = fsg_setup;
> +	fsg->function.disable = fsg_disable;
> +	fsg->function.unbind = fsg_unbind;
> +	fsg->function.free_func = fsg_free;
> +
> +	fsg->common = common;
> +	common->fsg = fsg;
> +
> +	return &fsg->function;
> +}
> +
> +static void fsg_free_instance(struct usb_function_instance *fi)
> +{
> +	struct f_ums_opts *opts = fsg_opts_from_func_inst(fi);
> +
> +	fsg_common_release(&opts->common->ref);
> +
> +	kfree(opts);
> +}
> +
> +static struct usb_function_instance *fsg_alloc_inst(void)
> +{
> +	struct f_ums_opts *opts;
> +
> +	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
> +	if (!opts)
> +		return ERR_PTR(-ENOMEM);
> +
> +	opts->func_inst.free_func_inst = fsg_free_instance;
> +
> +	opts->common = fsg_common_setup();
> +	if (!opts->common) {
> +		free(opts);
> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	return &opts->func_inst;
> +}
> +
> +DECLARE_USB_FUNCTION_INIT(ums, fsg_alloc_inst, fsg_alloc);
> +
> +#define STRING_MANUFACTURER_IDX		0
> +#define STRING_PRODUCT_IDX		1
> +#define STRING_DESCRIPTION_IDX		2
> +
> +static struct usb_string strings_dev[] = {
> +	[STRING_MANUFACTURER_IDX].s = NULL,
> +	[STRING_PRODUCT_IDX].s = NULL,
> +	[STRING_DESCRIPTION_IDX].s = "USB Mass Storage",
> +	{  } /* end of list */
> +};
> +
> +static struct usb_function_instance *fi_fsg;
> +static struct usb_function *f_fsg;
> +
> +static struct usb_configuration config = {
> +	.label			= "USB Mass Storage",
> +	.bConfigurationValue    = 1,
> +	.bmAttributes           = USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER,
> +	.iConfiguration		= 2,
> +};
> +
> +static int ums_driver_bind(struct usb_composite_dev *cdev)
> +{
> +	struct usb_gadget *gadget = cdev->gadget;
> +	int id;
> +
> +	if (gadget->vendor_id && gadget->product_id) {
> +		ums_dev_descriptor.idVendor = cpu_to_le16(gadget->vendor_id);
> +		ums_dev_descriptor.idProduct = cpu_to_le16(gadget->product_id);
> +	} else {
> +		ums_dev_descriptor.idVendor = cpu_to_le16(FSG_VENDOR_ID);
> +		ums_dev_descriptor.idProduct = cpu_to_le16(FSG_PRODUCT_ID);
> +	}
> +
> +	strings_dev[STRING_MANUFACTURER_IDX].s = gadget->manufacturer;
> +	strings_dev[STRING_PRODUCT_IDX].s = gadget->productname;
> +
> +	id = usb_string_id(cdev);
> +	if (id < 0)
> +		goto fail;
> +
> +	strings_dev[STRING_MANUFACTURER_IDX].id = id;
> +	ums_dev_descriptor.iManufacturer = id;
> +
> +	id = usb_string_id(cdev);
> +	if (id < 0)
> +		goto fail;
> +
> +	strings_dev[STRING_PRODUCT_IDX].id = id;
> +	ums_dev_descriptor.iProduct = id;
> +
> +	id = usb_add_config_only(cdev, &config);
> +	if (id)
> +		return id;
> +
> +	fi_fsg = usb_get_function_instance("ums");
> +	if (IS_ERR(fi_fsg)) {
> +		id = PTR_ERR(fi_fsg);
> +		goto fail;
> +	}
> +
> +	f_fsg = usb_get_function(fi_fsg);
> +	if (IS_ERR(f_fsg)) {
> +		id = PTR_ERR(f_fsg);
> +		goto fail;
> +	}
> +
> +	id = usb_add_function(&config, f_fsg);
> +	if (id)
> +		goto fail;
> +
> +	return 0;
> +fail:
> +	return id;
> +}
> +
> +static int ums_driver_unbind(struct usb_composite_dev *cdev)
> +{
> +	usb_put_function(f_fsg);
> +	usb_put_function_instance(fi_fsg);
> +
> +	return 0;
> +}
> +
> +static struct usb_composite_driver ums_driver = {
> +	.name		= "ums",
> +	.dev		= &ums_dev_descriptor,
> +	.strings	= fsg_strings_array,
> +	.max_speed	= USB_SPEED_HIGH,
> +	.bind		= ums_driver_bind,
> +	.unbind		= ums_driver_unbind,
> +};
> +
> +int usb_ums_register(struct f_ums_opts *opts)
> +{
> +	int ret;
> +
> +	if (ums_files)
> +		return -EBUSY;
> +
> +	ums_files = opts->files;
> +
> +	ret = usb_composite_probe(&ums_driver);
> +	if (ret)
> +		goto out;
> +
> +	while (poll())
> +		;
> +
> +	usb_composite_unregister(&ums_driver);
> +out:
> +	ums_files = NULL;
> +
> +	return ret;
> +}
> diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
> new file mode 100644
> index 000000000000..88cd745063e4
> --- /dev/null
> +++ b/drivers/usb/gadget/storage_common.c
> @@ -0,0 +1,173 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * storage_common.c -- Common definitions for mass storage functionality
> + *
> + * Copyright (C) 2003-2008 Alan Stern
> + * Copyeight (C) 2009 Samsung Electronics
> + * Author: Michal Nazarewicz (m.nazarewicz@xxxxxxxxxxx)
> + *
> + * Ported to u-boot:
> + * Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
> + *
> + * Code refactoring & cleanup:
> + * Łukasz Majewski <l.majewski@xxxxxxxxxxx>
> + */
> +
> +#include "storage_common.h"
> +
> +/*
> + * This file requires the following identifiers used in USB strings to
> + * be defined (each of type pointer to char):
> + *  - fsg_string_manufacturer -- name of the manufacturer
> + *  - fsg_string_product      -- name of the product
> + *  - fsg_string_serial       -- product's serial
> + *  - fsg_string_config       -- name of the configuration
> + *  - fsg_string_interface    -- name of the interface
> + * The first four are only needed when FSG_DESCRIPTORS_DEVICE_STRINGS
> + * macro is defined prior to including this file.
> + */
> +
> +/* There is only one interface. */
> +
> +struct usb_interface_descriptor fsg_intf_desc = {
> +	.bLength =		sizeof fsg_intf_desc,
> +	.bDescriptorType =	USB_DT_INTERFACE,
> +
> +	.bNumEndpoints =	2,		/* Adjusted during fsg_bind() */
> +	.bInterfaceClass =	USB_CLASS_MASS_STORAGE,
> +	.bInterfaceSubClass =	USB_SC_SCSI,	/* Adjusted during fsg_bind() */
> +	.bInterfaceProtocol =	USB_PR_BULK,	/* Adjusted during fsg_bind() */
> +	.iInterface =		FSG_STRING_INTERFACE,
> +};
> +
> +/*
> + * Three full-speed endpoint descriptors: bulk-in, bulk-out, and
> + * interrupt-in.
> + */
> +
> +struct usb_endpoint_descriptor fsg_fs_bulk_in_desc = {
> +	.bLength =		USB_DT_ENDPOINT_SIZE,
> +	.bDescriptorType =	USB_DT_ENDPOINT,
> +
> +	.bEndpointAddress =	USB_DIR_IN,
> +	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
> +	/* wMaxPacketSize set by autoconfiguration */
> +};
> +
> +struct usb_endpoint_descriptor fsg_fs_bulk_out_desc = {
> +	.bLength =		USB_DT_ENDPOINT_SIZE,
> +	.bDescriptorType =	USB_DT_ENDPOINT,
> +
> +	.bEndpointAddress =	USB_DIR_OUT,
> +	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
> +	/* wMaxPacketSize set by autoconfiguration */
> +};
> +
> +struct usb_descriptor_header *fsg_fs_function[] = {
> +	(struct usb_descriptor_header *) &fsg_intf_desc,
> +	(struct usb_descriptor_header *) &fsg_fs_bulk_in_desc,
> +	(struct usb_descriptor_header *) &fsg_fs_bulk_out_desc,
> +	NULL,
> +};
> +
> +/*
> + * USB 2.0 devices need to expose both high speed and full speed
> + * descriptors, unless they only run at full speed.
> + *
> + * That means alternate endpoint descriptors (bigger packets)
> + * and a "device qualifier" ... plus more construction options
> + * for the configuration descriptor.
> + */
> +struct usb_endpoint_descriptor fsg_hs_bulk_in_desc = {
> +	.bLength =		USB_DT_ENDPOINT_SIZE,
> +	.bDescriptorType =	USB_DT_ENDPOINT,
> +
> +	/* bEndpointAddress copied from fs_bulk_in_desc during fsg_bind() */
> +	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
> +	.wMaxPacketSize =	cpu_to_le16(512),
> +};
> +
> +struct usb_endpoint_descriptor fsg_hs_bulk_out_desc = {
> +	.bLength =		USB_DT_ENDPOINT_SIZE,
> +	.bDescriptorType =	USB_DT_ENDPOINT,
> +
> +	/* bEndpointAddress copied from fs_bulk_out_desc during fsg_bind() */
> +	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
> +	.wMaxPacketSize =	cpu_to_le16(512),
> +	.bInterval =		1,	/* NAK every 1 uframe */
> +};
> +
> +struct usb_descriptor_header *fsg_hs_function[] = {
> +	(struct usb_descriptor_header *) &fsg_intf_desc,
> +	(struct usb_descriptor_header *) &fsg_hs_bulk_in_desc,
> +	(struct usb_descriptor_header *) &fsg_hs_bulk_out_desc,
> +	NULL,
> +};
> +
> +/* Maxpacket and other transfer characteristics vary by speed. */
> +struct usb_endpoint_descriptor *
> +fsg_ep_desc(struct usb_gadget *g, struct usb_endpoint_descriptor *fs,
> +		struct usb_endpoint_descriptor *hs)
> +{
> +	if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
> +		return hs;
> +	return fs;
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +/*
> + * If the next two routines are called while the gadget is registered,
> + * the caller must own fsg->filesem for writing.
> + */
> +
> +int fsg_lun_open(struct fsg_lun *curlun, unsigned int num_sectors,
> +		 const char *filename)
> +{
> +	int				ro;
> +
> +	/* R/W if we can, R/O if we must */
> +	ro = curlun->initially_ro;
> +
> +	curlun->ro = ro;
> +	curlun->file_length = num_sectors << 9;
> +	curlun->num_sectors = num_sectors;
> +	debug("open backing file: %s\n", filename);
> +
> +	return 0;
> +}
> +
> +void fsg_lun_close(struct fsg_lun *curlun)
> +{
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +/*
> + * Sync the file data, don't bother with the metadata.
> + * This code was copied from fs/buffer.c:sys_fdatasync().
> + */
> +int fsg_lun_fsync_sub(struct fsg_lun *curlun)
> +{
> +	return 0;
> +}
> +
> +void store_cdrom_address(u8 *dest, int msf, u32 addr)
> +{
> +	if (msf) {
> +		/* Convert to Minutes-Seconds-Frames */
> +		addr >>= 2;		/* Convert to 2048-byte frames */
> +		addr += 2*75;		/* Lead-in occupies 2 seconds */
> +		dest[3] = addr % 75;	/* Frames */
> +		addr /= 75;
> +		dest[2] = addr % 60;	/* Seconds */
> +		addr /= 60;
> +		dest[1] = addr;		/* Minutes */
> +		dest[0] = 0;		/* Reserved */
> +	} else {
> +		/* Absolute sector */
> +		put_unaligned_be32(addr, dest);
> +	}
> +}
> +
> +/*-------------------------------------------------------------------------*/
> diff --git a/drivers/usb/gadget/storage_common.h b/drivers/usb/gadget/storage_common.h
> new file mode 100644
> index 000000000000..ce07a7dac72c
> --- /dev/null
> +++ b/drivers/usb/gadget/storage_common.h
> @@ -0,0 +1,245 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef USB_STORAGE_COMMON_H
> +#define USB_STORAGE_COMMON_H
> +
> +#include <driver.h>
> +#include <usb/storage.h>
> +#include <asm/unaligned.h>
> +#include <usb/mass_storage.h>
> +
> +#ifndef DEBUG
> +#undef VERBOSE_DEBUG
> +#undef DUMP_MSGS
> +#endif /* !DEBUG */
> +
> +#define VLDBG(lun, fmt, args...)  dev_vdbg(&(lun)->dev, fmt, ## args)
> +#define LDBG(lun, fmt, args...)   dev_dbg (&(lun)->dev, fmt, ## args)
> +#define LERROR(lun, fmt, args...) dev_err (&(lun)->dev, fmt, ## args)
> +#define LWARN(lun, fmt, args...)  dev_warn(&(lun)->dev, fmt, ## args)
> +#define LINFO(lun, fmt, args...)  dev_info(&(lun)->dev, fmt, ## args)
> +
> +/*
> + * Keep those macros in sync with those in
> + * include/linux/usb/composite.h or else GCC will complain.  If they
> + * are identical (the same names of arguments, white spaces in the
> + * same places) GCC will allow redefinition otherwise (even if some
> + * white space is removed or added) warning will be issued.
> + *
> + * Those macros are needed here because File Storage Gadget does not
> + * include the composite.h header.  For composite gadgets those macros
> + * are redundant since composite.h is included any way.
> + *
> + * One could check whether those macros are already defined (which
> + * would indicate composite.h had been included) or not (which would
> + * indicate we were in FSG) but this is not done because a warning is
> + * desired if definitions here differ from the ones in composite.h.
> + *
> + * We want the definitions to match and be the same in File Storage
> + * Gadget as well as Mass Storage Function (and so composite gadgets
> + * using MSF).  If someone changes them in composite.h it will produce
> + * a warning in this file when building MSF.
> + */
> +
> +#define DBG(d, fmt, args...) \
> +	dev_dbg(&(d)->gadget->dev , fmt , ## args)
> +#define VDBG(d, fmt, args...) \
> +	dev_vdbg(&(d)->gadget->dev , fmt , ## args)
> +#define ERROR(d, fmt, args...) \
> +	dev_err(&(d)->gadget->dev , fmt , ## args)
> +#define WARNING(d, fmt, args...) \
> +	dev_warn(&(d)->gadget->dev , fmt , ## args)
> +#define INFO(d, fmt, args...) \
> +	dev_info(&(d)->gadget->dev , fmt , ## args)
> +
> +#ifdef DUMP_MSGS
> +
> +/* dump_msg(fsg, const char * label, const u8 * buf, unsigned length); */
> +# define dump_msg(fsg, label, buf, length) do {                         \
> +	if (length < 512) {						\
> +		DBG(fsg, "%s, length %u:\n", label, length);		\
> +		print_hex_dump("", DUMP_PREFIX_OFFSET,	\
> +			       16, 1, buf, length, 0);			\
> +	}								\
> +} while (0)
> +
> +#  define dump_cdb(fsg) do { } while (0)
> +
> +#else
> +
> +#  define dump_msg(fsg, /* const char * */ label, \
> +		   /* const u8 * */ buf, /* unsigned */ length) do { } while (0)
> +
> +#  ifdef VERBOSE_DEBUG
> +
> +#    define dump_cdb(fsg)						\
> +	print_hex_dump("SCSI CDB: ", DUMP_PREFIX_NONE,	\
> +		       16, 1, (fsg)->cmnd, (fsg)->cmnd_size, 0)		\
> +
> +#  else
> +
> +#    define dump_cdb(fsg) do { } while (0)
> +
> +#  endif /* VERBOSE_DEBUG */
> +
> +#endif /* DUMP_MSGS */
> +
> +/*
> + * Thanks to NetChip Technologies for donating this product ID.
> + *
> + * DO NOT REUSE THESE IDs with any other driver!!  Ever!!
> + * Instead:  allocate your own, using normal USB-IF procedures.
> + */
> +
> +#define FSG_VENDOR_ID	0x0525	/* NetChip */
> +#define FSG_PRODUCT_ID	0xa4a5	/* Linux-USB File-backed Storage Gadget */
> +
> +/* Length of a SCSI Command Data Block */
> +#define MAX_COMMAND_SIZE	16
> +
> +/* SCSI Sense Key/Additional Sense Code/ASC Qualifier values */
> +#define SS_NO_SENSE				0
> +#define SS_COMMUNICATION_FAILURE		0x040800
> +#define SS_INVALID_COMMAND			0x052000
> +#define SS_INVALID_FIELD_IN_CDB			0x052400
> +#define SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE	0x052100
> +#define SS_LOGICAL_UNIT_NOT_SUPPORTED		0x052500
> +#define SS_MEDIUM_NOT_PRESENT			0x023a00
> +#define SS_MEDIUM_REMOVAL_PREVENTED		0x055302
> +#define SS_NOT_READY_TO_READY_TRANSITION	0x062800
> +#define SS_RESET_OCCURRED			0x062900
> +#define SS_SAVING_PARAMETERS_NOT_SUPPORTED	0x053900
> +#define SS_UNRECOVERED_READ_ERROR		0x031100
> +#define SS_WRITE_ERROR				0x030c02
> +#define SS_WRITE_PROTECTED			0x072700
> +
> +#define SK(x)		((u8) ((x) >> 16))	/* Sense Key byte, etc. */
> +#define ASC(x)		((u8) ((x) >> 8))
> +#define ASCQ(x)		((u8) (x))
> +
> +/*-------------------------------------------------------------------------*/
> +
> +struct fsg_lun {
> +	loff_t		file_length;
> +	loff_t		num_sectors;
> +
> +	unsigned int	initially_ro:1;
> +	unsigned int	ro:1;
> +	unsigned int	removable:1;
> +	unsigned int	cdrom:1;
> +	unsigned int	prevent_medium_removal:1;
> +	unsigned int	registered:1;
> +	unsigned int	info_valid:1;
> +	unsigned int	nofua:1;
> +
> +	u32		sense_data;
> +	u32		sense_data_info;
> +	u32		unit_attention_data;
> +
> +	struct device_d	dev;
> +};
> +
> +#define fsg_lun_is_open(curlun)	((curlun)->filp != NULL)
> +
> +/* Big enough to hold our biggest descriptor */
> +#define EP0_BUFSIZE	256
> +#define DELAYED_STATUS	(EP0_BUFSIZE + 999)	/* An impossibly large value */
> +
> +/* Number of buffers we will use.  2 is enough for double-buffering */
> +#define FSG_NUM_BUFFERS	2
> +
> +/* Default size of buffer length. */
> +#define FSG_BUFLEN	((u32)131072)
> +
> +/* Maximal number of LUNs supported in mass storage function */
> +#define FSG_MAX_LUNS	8
> +
> +enum fsg_buffer_state {
> +	BUF_STATE_EMPTY = 0,
> +	BUF_STATE_FULL,
> +	BUF_STATE_BUSY
> +};
> +
> +/*
> + * When FSG_BUFFHD_STATIC_BUFFER is defined when this file is included
> + * the fsg_buffhd structure's buf field will be an array of FSG_BUFLEN
> + * characters rather then a pointer to void.
> + */
> +
> +struct fsg_buffhd {
> +	void				*buf;
> +	enum fsg_buffer_state		state;
> +	struct fsg_buffhd		*next;
> +
> +	/*
> +	 * The NetChip 2280 is faster, and handles some protocol faults
> +	 * better, if we don't submit any short bulk-out read requests.
> +	 * So we will record the intended request length here.
> +	 */
> +	unsigned int			bulk_out_intended_length;
> +
> +	struct usb_request		*inreq;
> +	int				inreq_busy;
> +	struct usb_request		*outreq;
> +	int				outreq_busy;
> +};
> +
> +enum fsg_state {
> +	/* This one isn't used anywhere */
> +	FSG_STATE_COMMAND_PHASE = -10,
> +	FSG_STATE_DATA_PHASE,
> +	FSG_STATE_STATUS_PHASE,
> +
> +	FSG_STATE_IDLE = 0,
> +	FSG_STATE_ABORT_BULK_OUT,
> +	FSG_STATE_RESET,
> +	FSG_STATE_INTERFACE_CHANGE,
> +	FSG_STATE_CONFIG_CHANGE,
> +	FSG_STATE_DISCONNECT,
> +	FSG_STATE_EXIT,
> +	FSG_STATE_TERMINATED
> +};
> +
> +enum data_direction {
> +	DATA_DIR_UNKNOWN = 0,
> +	DATA_DIR_FROM_HOST,
> +	DATA_DIR_TO_HOST,
> +	DATA_DIR_NONE
> +};
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static inline u32 get_unaligned_be24(u8 *buf)
> +{
> +	return 0xffffff & (u32) get_unaligned_be32(buf - 1);
> +}
> +
> +/*-------------------------------------------------------------------------*/
> +
> +enum {
> +	FSG_STRING_INTERFACE
> +};
> +
> +/*-------------------------------------------------------------------------*/
> +
> +extern struct usb_interface_descriptor fsg_intf_desc;
> +
> +extern struct usb_endpoint_descriptor fsg_fs_bulk_in_desc;
> +extern struct usb_endpoint_descriptor fsg_fs_bulk_out_desc;
> +extern struct usb_descriptor_header *fsg_fs_function[];
> +
> +extern struct usb_endpoint_descriptor fsg_hs_bulk_in_desc;
> +extern struct usb_endpoint_descriptor fsg_hs_bulk_out_desc;
> +extern struct usb_descriptor_header *fsg_hs_function[];
> +
> +int fsg_lun_open(struct fsg_lun *curlun, unsigned int num_sectors,
> +		 const char *filename);
> +void fsg_lun_close(struct fsg_lun *curlun);
> +
> +struct usb_endpoint_descriptor *
> +fsg_ep_desc(struct usb_gadget *g, struct usb_endpoint_descriptor *fs,
> +		struct usb_endpoint_descriptor *hs);
> +int fsg_lun_fsync_sub(struct fsg_lun *curlun);
> +void store_cdrom_address(u8 *dest, int msf, u32 addr);
> +
> +#endif /* USB_STORAGE_COMMON_H */
> diff --git a/include/scsi.h b/include/scsi.h
> index e2397489ead9..7252b8ce3b62 100644
> --- a/include/scsi.h
> +++ b/include/scsi.h
> @@ -109,11 +109,14 @@
>  #define SCSI_MED_REMOVL	0x1E		/* Prevent/Allow medium Removal (O) */
>  #define SCSI_READ6	0x08		/* Read 6-byte (MANDATORY) */
>  #define SCSI_READ10	0x28		/* Read 10-byte (MANDATORY) */
> +#define SCSI_READ12	0xA8		/* Read 12-byte (O) */
>  #define SCSI_RD_CAPAC	0x25		/* Read Capacity (MANDATORY) */
> +#define SCSI_RD_FMT_CAPAC	0x23
>  #define SCSI_RD_DEFECT	0x37		/* Read Defect Data (O) */
>  #define SCSI_READ_LONG	0x3E		/* Read Long (O) */
>  #define SCSI_REASS_BLK	0x07		/* Reassign Blocks (O) */
>  #define SCSI_RCV_DIAG	0x1C		/* Receive Diagnostic Results (O) */
> +#define SCSI_RESERVE	0x16
>  #define SCSI_RELEASE	0x17		/* Release Unit (MANDATORY) */
>  #define SCSI_REZERO	0x01		/* Rezero Unit (O) */
>  #define SCSI_SRCH_DAT_E	0x31		/* Search Data Equal (O) */
> @@ -128,9 +131,12 @@
>  #define SCSI_VERIFY	0x2F		/* Verify (O) */
>  #define SCSI_WRITE6	0x0A		/* Write 6-Byte (MANDATORY) */
>  #define SCSI_WRITE10	0x2A		/* Write 10-Byte (MANDATORY) */
> +#define SCSI_WRITE12	0xAA		/* Write 12-Byte (O) */
>  #define SCSI_WRT_VERIFY	0x2E		/* Write and Verify (O) */
>  #define SCSI_WRITE_LONG	0x3F		/* Write Long (O) */
>  #define SCSI_WRITE_SAME	0x41		/* Write Same (O) */
> +#define SCSI_RD_TOC	0x43
> +#define SCSI_RD_HEADER	0x44
>  
>  
>  /****************************************************************************
> @@ -165,4 +171,10 @@ void scsi_init(void);
>  #define FALSE 0
>  #endif
>  
> +/*
> + *  DEVICE TYPES
> + */
> +
> +#define TYPE_DISK           0x00
> +
>  #endif /* _SCSI_H */
> diff --git a/include/usb/mass_storage.h b/include/usb/mass_storage.h
> new file mode 100644
> index 000000000000..084b3c8e8f31
> --- /dev/null
> +++ b/include/usb/mass_storage.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Copyright (C) 2011 Samsung Electrnoics
> + * Lukasz Majewski <l.majewski@xxxxxxxxxxx>
> + */
> +
> +#ifndef __USB_MASS_STORAGE_H__
> +#define __USB_MASS_STORAGE_H__
> +
> +#include <usb/composite.h>
> +
> +/* Wait at maximum 60 seconds for cable connection */
> +#define UMS_CABLE_READY_TIMEOUT	60
> +
> +struct fsg_common;
> +
> +struct f_ums_opts {
> +	struct usb_function_instance func_inst;
> +	struct fsg_common *common;
> +	struct file_list *files;
> +	unsigned int num_sectors;
> +	int fd;
> +	char name[16];
> +};
> +
> +int usb_ums_register(struct f_ums_opts *);
> +
> +#endif /* __USB_MASS_STORAGE_H__ */
> diff --git a/include/usb/storage.h b/include/usb/storage.h
> new file mode 100644
> index 000000000000..e0240f864548
> --- /dev/null
> +++ b/include/usb/storage.h
> @@ -0,0 +1,87 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#ifndef __LINUX_USB_STORAGE_H
> +#define __LINUX_USB_STORAGE_H
> +
> +/*
> + * linux/usb/storage.h
> + *
> + * Copyright Matthew Wilcox for Intel Corp, 2010
> + *
> + * This file contains definitions taken from the
> + * USB Mass Storage Class Specification Overview
> + *
> + * Distributed under the terms of the GNU GPL, version two.
> + */
> +
> +/* Storage subclass codes */
> +
> +#define USB_SC_RBC	0x01		/* Typically, flash devices */
> +#define USB_SC_8020	0x02		/* CD-ROM */
> +#define USB_SC_QIC	0x03		/* QIC-157 Tapes */
> +#define USB_SC_UFI	0x04		/* Floppy */
> +#define USB_SC_8070	0x05		/* Removable media */
> +#define USB_SC_SCSI	0x06		/* Transparent */
> +#define USB_SC_LOCKABLE	0x07		/* Password-protected */
> +
> +#define USB_SC_ISD200	0xf0		/* ISD200 ATA */
> +#define USB_SC_CYP_ATACB	0xf1	/* Cypress ATACB */
> +#define USB_SC_DEVICE	0xff		/* Use device's value */
> +
> +/* Storage protocol codes */
> +
> +#define USB_PR_CBI	0x00		/* Control/Bulk/Interrupt */
> +#define USB_PR_CB	0x01		/* Control/Bulk w/o interrupt */
> +#define USB_PR_BULK	0x50		/* bulk only */
> +#define USB_PR_UAS	0x62		/* USB Attached SCSI */
> +
> +#define USB_PR_USBAT	0x80		/* SCM-ATAPI bridge */
> +#define USB_PR_EUSB_SDDR09	0x81	/* SCM-SCSI bridge for SDDR-09 */
> +#define USB_PR_SDDR55	0x82		/* SDDR-55 (made up) */
> +#define USB_PR_DPCM_USB	0xf0		/* Combination CB/SDDR09 */
> +#define USB_PR_FREECOM	0xf1		/* Freecom */
> +#define USB_PR_DATAFAB	0xf2		/* Datafab chipsets */
> +#define USB_PR_JUMPSHOT	0xf3		/* Lexar Jumpshot */
> +#define USB_PR_ALAUDA	0xf4		/* Alauda chipsets */
> +#define USB_PR_KARMA	0xf5		/* Rio Karma */
> +
> +#define USB_PR_DEVICE	0xff		/* Use device's value */
> +
> +/*
> + * Bulk only data structures
> + */
> +
> +/* command block wrapper */
> +struct bulk_cb_wrap {
> +	__le32	Signature;		/* contains 'USBC' */
> +	__u32	Tag;			/* unique per command id */
> +	__le32	DataTransferLength;	/* size of data */
> +	__u8	Flags;			/* direction in bit 0 */
> +	__u8	Lun;			/* LUN normally 0 */
> +	__u8	Length;			/* length of the CDB */
> +	__u8	CDB[16];		/* max command */
> +};
> +
> +#define US_BULK_CB_WRAP_LEN	31
> +#define US_BULK_CB_SIGN		0x43425355	/* spells out 'USBC' */
> +#define US_BULK_FLAG_IN		(1 << 7)
> +#define US_BULK_FLAG_OUT	0
> +
> +/* command status wrapper */
> +struct bulk_cs_wrap {
> +	__le32	Signature;	/* contains 'USBS' */
> +	__u32	Tag;		/* same as original command */
> +	__le32	Residue;	/* amount not transferred */
> +	__u8	Status;		/* see below */
> +};
> +
> +#define US_BULK_CS_WRAP_LEN	13
> +#define US_BULK_CS_SIGN		0x53425355      /* spells out 'USBS' */
> +#define US_BULK_STAT_OK		0
> +#define US_BULK_STAT_FAIL	1
> +#define US_BULK_STAT_PHASE	2
> +
> +/* bulk-only class specific requests */
> +#define US_BULK_RESET_REQUEST   0xff
> +#define US_BULK_GET_MAX_LUN     0xfe
> +
> +#endif
> 

-- 
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