[PATCH 24/24] [Storage] Comments updated

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Signed-off-by: Michal Nazarewicz <m.nazarewicz@xxxxxxxxxxx>
---
 drivers/usb/gadget/f_mass_storage.c |  193 +++++++++++++++++++++++------------
 drivers/usb/gadget/mass_storage.c   |    6 +-
 2 files changed, 129 insertions(+), 70 deletions(-)

diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index 49d7baa..b3c1a11 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -1,7 +1,9 @@
 /*
- * file_storage.c -- File-backed USB Storage Gadget, for USB development
+ * 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.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -37,45 +39,113 @@
 
 
 /*
- * The File-backed Storage Gadget 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 gadget driver for a USB
- * device, it also illustrates a technique of double-buffering for increased
- * throughput.  Last but not least, it gives an easy way to probe the
- * behavior of the Mass Storage drivers in a USB host.
+ * 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.
  *
- * Backing storage is provided by a regular file or a block device, specified
- * by the "file" module parameter.  Access can be limited to read-only by
- * setting the optional "ro" module parameter.  (For CD-ROM emulation,
- * access is always read-only.)  The gadget will indicate that it has
- * removable media if the optional "removable" module parameter is set.
+ * 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.)
  *
- * The gadget supports the Control-Bulk (CB), Control-Bulk-Interrupt (CBI),
- * and Bulk-Only (also known as Bulk-Bulk-Bulk or BBB) transports, selected
- * by the optional "transport" module parameter.  It also supports the
- * following protocols: RBC (0x01), ATAPI or SFF-8020i (0x02), QIC-157 (0c03),
- * UFI (0x04), SFF-8070i (0x05), and transparent SCSI (0x06), selected by
- * the optional "protocol" module parameter.  In addition, the default
- * Vendor ID, Product ID, and release number can be overridden.
  *
- * There is support for multiple logical units (LUNs), each of which has
- * its own backing file.  The number of LUNs can be set using the optional
- * "luns" module parameter (anywhere from 1 to 8), and the corresponding
- * files are specified using comma-separated lists for "file" and "ro".
- * The default number of LUNs is taken from the number of "file" elements;
- * it is 1 if "file" is not given.  If "removable" is not set then a backing
- * file must be specified for each LUN.  If it is set, then an unspecified
- * or empty backing filename means the LUN's medium is not loaded.  Ideally
- * each LUN would be settable independently as a disk drive or a CD-ROM
- * drive, but currently all LUNs have to be the same type.  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 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, booleans 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 (an interrupt-out endpoint is also needed for CBI).  The memory
- * requirement amounts to two 16K buffers, size configurable by a parameter.
- * Support is included for both full-speed and high-speed operation.
+ * 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
@@ -83,39 +153,28 @@
  * issue, but there may be some with hardware restrictions that prevent
  * a buffer from being used by more than one endpoint.
  *
- * Module options:
  *
- *	file=filename[,filename...]
- *				Required if "removable" is not set, names of
- *					the files or block devices used for
- *					backing storage
- *	ro=b[,b...]		Default false, booleans for read-only access
- *	removable		Default false, boolean for removable media
- *	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
- *	cdrom			Default false, boolean for whether to emulate
- *					a CD-ROM drive
+ * 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.
  *
- * The pathnames of the backing files and the ro settings are available in
- * the attribute files "file" and "ro" in the lun<n> 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.
  *
- * This gadget driver 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
+ * 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>.
  */
 
@@ -123,7 +182,7 @@
 /*
  *				Driver Design
  *
- * The FSG driver is fairly straightforward.  There is a main kernel
+ * 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.
@@ -244,7 +303,7 @@
 /*-------------------------------------------------------------------------*/
 
 #define FSG_DRIVER_DESC		"Mass Storage Function"
-#define FSG_DRIVER_VERSION	"20 November 2008"
+#define FSG_DRIVER_VERSION	"2009/09/11"
 
 static const char fsg_string_interface[] = "Mass Storage";
 
diff --git a/drivers/usb/gadget/mass_storage.c b/drivers/usb/gadget/mass_storage.c
index bd9c8a8..3b99b2f 100644
--- a/drivers/usb/gadget/mass_storage.c
+++ b/drivers/usb/gadget/mass_storage.c
@@ -1,10 +1,10 @@
 /*
- * mass_storage.c -- File-backed USB Storage Gadget, for USB development
+ * mass_storage.c -- Mass Storage USB Gadget
  *
  * Copyright (C) 2003-2008 Alan Stern
- *
  * Copyright (C) 2009 Samsung Electronics
  *                    Author: Michal Nazarewicz <m.nazarewicz@xxxxxxxxxxx>
+ * All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -45,7 +45,7 @@
 /*-------------------------------------------------------------------------*/
 
 #define DRIVER_DESC		"Mass Storage Gadget"
-#define DRIVER_VERSION		"2009/07/21"
+#define DRIVER_VERSION		"2009/09/11"
 
 /*-------------------------------------------------------------------------*/
 
-- 
1.6.3.3


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