Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Johan Hovold <johan@xxxxxxxxxx>]

On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:
> This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
> Master Adapter DLN-2. Details about the device can be found here:
> 
> https://www.diolan.com/i2c/i2c_interface.html.
> 
> Information about the USB protocol can be found in the Programmer's
> Reference Manual [1], see section 1.7.
> 
> Because the hardware has a single transmit endpoint and a single
> receive endpoint the communication between the various DLN2 drivers
> and the hardware will be muxed/demuxed by this driver.
> 
> Each DLN2 module will be identified by the handle field within the DLN2
> message header. If a DLN2 module issues multiple commands in parallel
> they will be identified by the echo counter field in the message header.
> 
> The DLN2 modules can use the dln2_transfer() function to issue a
> command and wait for its response. They can also register a callback
> that is going to be called when a specific event id is generated by
> the device (e.g. GPIO interrupts). The device uses handle 0 for
> sending events.
> 
> [1] https://www.diolan.com/downloads/dln-api-manual.pdf
> 
> Signed-off-by: Octavian Purdila <octavian.purdila@xxxxxxxxx>
> ---
>  drivers/mfd/Kconfig      |   9 +
>  drivers/mfd/Makefile     |   1 +
>  drivers/mfd/dln2.c       | 758 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/dln2.h |  67 +++++
>  4 files changed, 835 insertions(+)
>  create mode 100644 drivers/mfd/dln2.c
>  create mode 100644 include/linux/mfd/dln2.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index de5abf2..7bcf895 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -183,6 +183,15 @@ config MFD_DA9063
>  	  Additional drivers must be enabled in order to use the functionality
>  	  of the device.
>  
> +config MFD_DLN2
> +	tristate "Diolan DLN2 support"
> +	select MFD_CORE
> +	depends on USB
> +	help
> +	  This adds support for Diolan USB-I2C/SPI/GPIO Master Adapter DLN-2.
> +	  Additional drivers must be enabled in order to use the functionality
> +	  of the device.
> +
>  config MFD_MC13XXX
>  	tristate
>  	depends on (SPI_MASTER || I2C)
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index f001487..591988d 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -169,6 +169,7 @@ obj-$(CONFIG_MFD_AS3711)	+= as3711.o
>  obj-$(CONFIG_MFD_AS3722)	+= as3722.o
>  obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
>  obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
> +obj-$(CONFIG_MFD_DLN2)		+= dln2.o
>  
>  intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
>  obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
> diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
> new file mode 100644
> index 0000000..36c53cd
> --- /dev/null
> +++ b/drivers/mfd/dln2.c
> @@ -0,0 +1,758 @@
> +/*
> + * Driver for the Diolan DLN-2 USB adapter
> + *
> + * Copyright (c) 2014 Intel Corporation
> + *
> + * Derived from:
> + *  i2c-diolan-u2c.c
> + *  Copyright (c) 2010-2011 Ericsson AB
> + *
> + * 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 the Free Software Foundation, version 2.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/dln2.h>
> +#include <linux/rculist.h>
> +
> +struct dln2_header {
> +	__le16 size;
> +	__le16 id;
> +	__le16 echo;
> +	__le16 handle;
> +} __packed;
> +
> +struct dln2_response {
> +	struct dln2_header hdr;
> +	__le16 result;
> +} __packed;
> +
> +#define DLN2_GENERIC_MODULE_ID		0x00
> +#define DLN2_GENERIC_CMD(cmd)		DLN2_CMD(cmd, DLN2_GENERIC_MODULE_ID)
> +#define CMD_GET_DEVICE_VER		DLN2_GENERIC_CMD(0x30)
> +#define CMD_GET_DEVICE_SN		DLN2_GENERIC_CMD(0x31)
> +
> +#define DLN2_HW_ID			0x200
> +#define DLN2_USB_TIMEOUT		200	/* in ms */
> +#define DLN2_MAX_RX_SLOTS		16
> +#define DLN2_MAX_URBS			16
> +#define DLN2_RX_BUF_SIZE		512
> +
> +#define DLN2_HANDLE_EVENT		0
> +#define DLN2_HANDLE_CTRL		1
> +#define DLN2_HANDLE_GPIO		2
> +#define DLN2_HANDLE_I2C			3
> +#define DLN2_HANDLES			4

This should be an enum.

> +
> +
> +/*
> + * Receive context used between the receive demultiplexer and the
> + * transfer routine. While sending a request the transfer routine
> + * will look for a free receive context and use it to wait for a
> + * response and to receive the URB and thus the response data.
> + */
> +struct dln2_rx_context {
> +	/* completion used to wait a response */

wait for

> +	struct completion done;
> +
> +	/* if non-NULL the URB contains the response */
> +	struct urb *urb;
> +
> +	/* if true then this context is used to wait for a response */
> +	bool connected;

Now that you have a disconnected flag, perhaps you can rename this to
something more descriptive as, for example, in_use.

> +
> +	/* cancel waiting for a response, e.g. on USB disconnect */
> +	bool cancel;

You this new field now, but never use it.

> +};
> +
> +/*
> + * Receive contexts for a particular DLN2 module (i2c, gpio, etc.). We
> + * use the handle header field to indentify the module in

identify

> + * dln2_dev.mod_rx_slots and then the echo header field to index the
> + * slots field and find the receive context for a particular
> + * request.
> + */
> +struct dln2_mod_rx_slots {
> +	/* RX slots bitmap */
> +	unsigned long bmap;
> +
> +	/* used to wait for a free RX slot */
> +	wait_queue_head_t wq;
> +
> +	/* used to wait for an RX operation to complete */
> +	struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
> +
> +	/* device has been disconnected */
> +	bool disconnected;

This belongs in the dln2_dev struct.

I think you're overcomplicating the disconnect handling by intertwining
it with your slots.

Add a lock, an active-transfer counter, a disconnected flag, and a wait
queue to struct dln2_dev.

More below.

> +
> +	/* avoid races between free_rx_slot, dln2_rx_transfer and dln2_stop */
> +	spinlock_t lock;
> +};
> +
> +struct dln2_dev {
> +	struct usb_device *usb_dev;
> +	struct usb_interface *interface;
> +	u8 ep_in;
> +	u8 ep_out;
> +
> +	struct urb *rx_urb[DLN2_MAX_URBS];
> +	void *rx_buf[DLN2_MAX_URBS];
> +
> +	struct dln2_mod_rx_slots mod_rx_slots[DLN2_HANDLES];
> +
> +	struct list_head rx_cb_list;
> +	spinlock_t rx_cb_lock;
> +};
> +
> +static bool find_free_slot(struct dln2_mod_rx_slots *rxs, int *slot)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	if (rxs->disconnected) {

Check the global disconnected flag. Locking not needed.

> +		*slot = -ECONNRESET;

-ENODEV

> +		goto out;
> +	}
> +
> +	*slot = find_first_zero_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
> +
> +	if (*slot < DLN2_MAX_RX_SLOTS) {
> +		struct dln2_rx_context *rxc = &rxs->slots[*slot];
> +
> +		set_bit(*slot, &rxs->bmap);
> +		rxc->connected = true;
> +	}
> +
> +out:
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	return *slot < DLN2_MAX_RX_SLOTS;
> +}
> +
> +static int alloc_rx_slot(struct dln2_mod_rx_slots *rxs)
> +{
> +	int ret;
> +	int slot;
> +
> +	/*
> +	 * No need to timeout here, the wait is bounded by the timeout
> +	 * in _dln2_transfer.
> +	 */
> +	ret = wait_event_interruptible(rxs->wq, find_free_slot(rxs, &slot));
> +	if (ret < 0)
> +		return ret;
> +
> +	return slot;
> +}
> +
> +static void free_rx_slot(struct dln2_dev *dln2, struct dln2_mod_rx_slots *rxs,
> +			 int slot)
> +{
> +	struct urb *urb = NULL;
> +	unsigned long flags;
> +	struct dln2_rx_context *rxc;
> +	struct device *dev = &dln2->interface->dev;
> +	int ret;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	clear_bit(slot, &rxs->bmap);
> +
> +	rxc = &rxs->slots[slot];
> +	rxc->connected = false;
> +	urb = rxc->urb;
> +	rxc->urb = NULL;
> +	reinit_completion(&rxc->done);
> +
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (urb) {
> +		ret = usb_submit_urb(urb, GFP_KERNEL);
> +		if (ret < 0)
> +			dev_err(dev, "failed to re-submit RX URB: %d\n", ret);
> +	}
> +
> +	wake_up_interruptible(&rxs->wq);
> +}

Could you move these three functions just above _dln2_transfer, which is
the only function they are used in?

> +
> +struct dln2_rx_cb_entry {
> +	struct list_head list;
> +	u16 id;
> +	struct platform_device *pdev;
> +	dln2_rx_cb_t callback;
> +};
> +
> +int dln2_register_event_cb(struct platform_device *pdev, u16 id,
> +			   dln2_rx_cb_t rx_cb)
> +{
> +	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> +	struct dln2_rx_cb_entry *i, *new;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	new = kmalloc(sizeof(*new), GFP_KERNEL);
> +	if (!new)
> +		return -ENOMEM;
> +
> +	new->id = id;
> +	new->callback = rx_cb;
> +	new->pdev = pdev;
> +
> +	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
> +
> +	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {

No need to use the _rcu version on the update side.

> +		if (i->id == id) {
> +			ret = -EBUSY;
> +			break;
> +		}
> +	}
> +
> +	if (!ret)
> +		list_add_rcu(&new->list, &dln2->rx_cb_list);
> +
> +	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
> +
> +	if (ret)
> +		kfree(new);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(dln2_register_event_cb);
> +
> +void dln2_unregister_event_cb(struct platform_device *pdev, u16 id)
> +{
> +	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> +	struct dln2_rx_cb_entry *i;
> +	unsigned long flags;
> +	bool found = false;
> +
> +	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
> +
> +	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {

No need to use the _rcu version on the update side.

> +		if (i->id == id) {
> +			list_del_rcu(&i->list);
> +			found = true;
> +			break;
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
> +
> +	if (found) {
> +		synchronize_rcu();
> +		kfree(i);
> +	}
> +}
> +EXPORT_SYMBOL(dln2_unregister_event_cb);
> +
> +static void dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
> +			     u16 handle, u16 rx_slot)
> +{
> +	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> +	struct dln2_rx_context *rxc;
> +	struct device *dev = &dln2->interface->dev;
> +	int err;
> +
> +	spin_lock(&rxs->lock);
> +	rxc = &rxs->slots[rx_slot];
> +	if (rxc->connected) {
> +		rxc->urb = urb;
> +		complete(&rxc->done);
> +	} else {
> +		dev_warn(dev, "dropping response %d/%d", handle, rx_slot);
> +		err = usb_submit_urb(urb, GFP_ATOMIC);
> +		if (err < 0)
> +			dev_err(dev, "failed to re-submit RX URB: %d\n", err);
> +	}
> +	spin_unlock(&rxs->lock);
> +}
> +
> +static void dln2_run_rx_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
> +				  void *data, int len)
> +{
> +	struct dln2_rx_cb_entry *i;
> +
> +	rcu_read_lock();
> +
> +	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list)
> +		if (i->id == id)
> +			i->callback(i->pdev, echo, data, len);
> +
> +	rcu_read_unlock();
> +}
> +
> +static void dln2_rx(struct urb *urb)
> +{
> +	int err;
> +	struct dln2_dev *dln2 = urb->context;
> +	struct dln2_header *hdr = urb->transfer_buffer;
> +	struct device *dev = &dln2->interface->dev;
> +	u16 id, echo, handle, size;
> +	u8 *data;
> +	int len;
> +
> +	switch (urb->status) {
> +	case 0:
> +		/* success */
> +		break;
> +	case -ECONNRESET:
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +	case -EPIPE:
> +		/* this urb is terminated, clean up */
> +		dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
> +		return;
> +	default:
> +		dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
> +		goto out;
> +	}
> +
> +	if (urb->actual_length < sizeof(struct dln2_header)) {
> +		dev_err(dev, "short response: %d\n", urb->actual_length);
> +		goto out;
> +	}
> +
> +	handle = le16_to_cpu(hdr->handle);
> +	id = le16_to_cpu(hdr->id);
> +	echo = le16_to_cpu(hdr->echo);
> +	size = le16_to_cpu(hdr->size);
> +
> +	if (size != urb->actual_length) {
> +		dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
> +			handle, id, echo, size, urb->actual_length);
> +		goto out;
> +	}
> +
> +	if (handle >= DLN2_HANDLES) {
> +		dev_warn(dev, "RX: invalid handle %d\n", handle);
> +		goto out;
> +	}
> +
> +	data = urb->transfer_buffer + sizeof(struct dln2_header);
> +	len = urb->actual_length - sizeof(struct dln2_header);
> +
> +	if (handle == DLN2_HANDLE_EVENT) {
> +		dln2_run_rx_callbacks(dln2, id, echo, data, len);
> +		err = usb_submit_urb(urb, GFP_ATOMIC);
> +		if (err < 0)
> +			goto out_submit_failed;
> +	} else {
> +		dln2_rx_transfer(dln2, urb, handle, echo);
> +	}
> +
> +	return;
> +
> +out:
> +	err = usb_submit_urb(urb, GFP_ATOMIC);
> +out_submit_failed:
> +	if (err < 0)
> +		dev_err(dev, "failed to re-submit RX URB: %d\n", err);
> +}
> +
> +static void *dln2_prep_buf(u16 handle, u16 cmd, u16 echo, const void *obuf,
> +			   int *obuf_len, gfp_t gfp)
> +{
> +	int len;
> +	void *buf;
> +	struct dln2_header *hdr;
> +
> +	len = *obuf_len + sizeof(*hdr);
> +	buf = kmalloc(len, gfp);
> +	if (!buf)
> +		return NULL;
> +
> +	hdr = (struct dln2_header *)buf;
> +	hdr->id = cpu_to_le16(cmd);
> +	hdr->size = cpu_to_le16(len);
> +	hdr->echo = cpu_to_le16(echo);
> +	hdr->handle = cpu_to_le16(handle);
> +
> +	memcpy(buf + sizeof(*hdr), obuf, *obuf_len);
> +
> +	*obuf_len = len;
> +
> +	return buf;
> +}
> +
> +static int dln2_send_wait(struct dln2_dev *dln2, u16 handle, u16 cmd, u16 echo,
> +			  const void *obuf, int obuf_len)
> +{
> +	int ret = 0;
> +	int len = obuf_len;
> +	void *buf;
> +	int actual;
> +
> +	buf = dln2_prep_buf(handle, cmd, echo, obuf, &len, GFP_KERNEL);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	ret = usb_bulk_msg(dln2->usb_dev,
> +			   usb_sndbulkpipe(dln2->usb_dev, dln2->ep_out),
> +			   buf, len, &actual, DLN2_USB_TIMEOUT);
> +
> +	kfree(buf);
> +
> +	return ret;
> +}
> +
> +static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
> +			  const void *obuf, unsigned obuf_len,
> +			  void *ibuf, unsigned *ibuf_len)
> +{
> +	int ret = 0;
> +	u16 result;
> +	int rx_slot;
> +	unsigned long flags;
> +	struct dln2_response *rsp;
> +	struct dln2_rx_context *rxc;
> +	struct device *dev;
> +	const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
> +	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> +

Check the disconnected flag before incrementing the transfer count
(while holding the device lock) here. Then decrement counter before
returning and wake up an waiters if disconnected below.

That is sufficient to implement wait-until-io-has-completed. Anything
else you do below and in the helper functions is only to speed things
up at disconnect (and can be done without locking the device).

> +	rx_slot = alloc_rx_slot(rxs);
> +	if (rx_slot < 0)
> +		return rx_slot;
> +
> +	dev = &dln2->interface->dev;
> +
> +	ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
> +	if (ret < 0) {
> +		free_rx_slot(dln2, rxs, rx_slot);

goto out_free_rx_slot

> +		dev_err(dev, "USB write failed: %d", ret);
> +		return ret;
> +	}
> +
> +	rxc = &rxs->slots[rx_slot];
> +
> +	ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
> +	if (ret <= 0) {
> +		if (!ret)
> +			ret = -ETIMEDOUT;
> +		goto out_free_rx_slot;
> +	}
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	if (!rxc->urb) {

Just check the disconnected flag directly here. Locking not needed (see
below).

> +		ret = -ECONNRESET;

-ENODEV

> +		spin_unlock_irqrestore(&rxs->lock, flags);
> +		goto out_free_rx_slot;
> +	}
> +
> +	/* if we got here we know that the response header has been checked */
> +	rsp = rxc->urb->transfer_buffer;
> +
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (rsp->hdr.size < sizeof(*rsp)) {
> +		ret = -EPROTO;
> +		goto out_free_rx_slot;
> +	}
> +
> +	result = le16_to_cpu(rsp->result);
> +	if (result) {
> +		dev_dbg(dev, "%d received response with error %d\n",
> +			handle, result);
> +		ret = -EREMOTEIO;
> +		goto out_free_rx_slot;
> +	}
> +
> +	if (!ibuf) {
> +		ret = 0;
> +		goto out_free_rx_slot;
> +	}
> +
> +	if (*ibuf_len > rsp->hdr.size - sizeof(*rsp))
> +		*ibuf_len = rsp->hdr.size - sizeof(*rsp);
> +
> +	memcpy(ibuf, rsp + 1, *ibuf_len);
> +
> +out_free_rx_slot:
> +	free_rx_slot(dln2, rxs, rx_slot);
> +
> +	return ret;
> +}
> +
> +int dln2_transfer(struct platform_device *pdev, u16 cmd,
> +		  const void *obuf, unsigned obuf_len,
> +		  void *ibuf, unsigned *ibuf_len)
> +{
> +	struct dln2_platform_data *dln2_pdata;
> +	struct dln2_dev *dln2;
> +	u16 h;
> +
> +	dln2 = dev_get_drvdata(pdev->dev.parent);
> +	dln2_pdata = dev_get_platdata(&pdev->dev);
> +	h = dln2_pdata->handle;
> +
> +	return _dln2_transfer(dln2, h, cmd, obuf, obuf_len, ibuf, ibuf_len);
> +}
> +EXPORT_SYMBOL(dln2_transfer);
> +
> +static int dln2_check_hw(struct dln2_dev *dln2)
> +{
> +	int ret;
> +	__le32 hw_type;
> +	int len = sizeof(hw_type);
> +
> +	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_VER,
> +			     NULL, 0, &hw_type, &len);
> +	if (ret < 0)
> +		return ret;
> +	if (len < sizeof(hw_type))
> +		return -EREMOTEIO;
> +
> +	if (le32_to_cpu(hw_type) != DLN2_HW_ID) {
> +		dev_err(&dln2->interface->dev, "Device ID 0x%x not supported",

Missing newline in message. Please check throughout all patches. There's
at least one more missing.

> +			le32_to_cpu(hw_type));
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static int dln2_print_serialno(struct dln2_dev *dln2)
> +{
> +	int ret;
> +	__le32 serial_no;
> +	int len = sizeof(serial_no);
> +	struct device *dev = &dln2->interface->dev;
> +
> +	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_SN, NULL, 0,
> +			     &serial_no, &len);
> +	if (ret < 0)
> +		return ret;
> +	if (len < sizeof(serial_no))
> +		return -EREMOTEIO;
> +
> +	dev_info(dev, "Diolan DLN2 serial 0x%x\n", le32_to_cpu(serial_no));
> +
> +	return 0;
> +}
> +
> +static int dln2_hw_init(struct dln2_dev *dln2)
> +{
> +	int ret;
> +
> +	ret = dln2_check_hw(dln2);
> +	if (ret < 0)
> +		return ret;
> +
> +	return dln2_print_serialno(dln2);
> +}
> +
> +static void dln2_free_rx_urbs(struct dln2_dev *dln2)
> +{
> +	int i;
> +
> +	for (i = 0; i < DLN2_MAX_URBS; i++) {
> +		usb_kill_urb(dln2->rx_urb[i]);
> +		usb_free_urb(dln2->rx_urb[i]);
> +		kfree(dln2->rx_buf[i]);
> +	}
> +}
> +
> +static void dln2_free(struct dln2_dev *dln2)
> +{
> +	dln2_free_rx_urbs(dln2);
> +	usb_put_dev(dln2->usb_dev);
> +	kfree(dln2);
> +}
> +
> +static int dln2_setup_rx_urbs(struct dln2_dev *dln2,
> +			      struct usb_host_interface *hostif)
> +{
> +	int i;
> +	const int rx_max_size = DLN2_RX_BUF_SIZE;
> +	struct device *dev = &dln2->interface->dev;
> +
> +	for (i = 0; i < DLN2_MAX_URBS; i++) {
> +		int ret;
> +
> +		dln2->rx_buf[i] = kmalloc(rx_max_size, GFP_KERNEL);
> +		if (!dln2->rx_buf[i])
> +			return -ENOMEM;
> +
> +		dln2->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
> +		if (!dln2->rx_urb[i])
> +			return -ENOMEM;
> +
> +		usb_fill_bulk_urb(dln2->rx_urb[i], dln2->usb_dev,
> +				  usb_rcvbulkpipe(dln2->usb_dev, dln2->ep_in),
> +				  dln2->rx_buf[i], rx_max_size, dln2_rx, dln2);
> +
> +		ret = usb_submit_urb(dln2->rx_urb[i], GFP_KERNEL);
> +		if (ret < 0) {
> +			dev_err(dev, "failed to submit RX URB: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static struct dln2_platform_data dln2_pdata_gpio = {
> +	.handle = DLN2_HANDLE_GPIO,
> +};
> +
> +/* Only one I2C port seems to be supported on current hardware */
> +static struct dln2_platform_data dln2_pdata_i2c = {
> +	.handle = DLN2_HANDLE_I2C,
> +	.port = 0,
> +};
> +
> +static const struct mfd_cell dln2_devs[] = {
> +	{
> +		.name = "dln2-gpio",
> +		.platform_data = &dln2_pdata_gpio,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +	{
> +		.name = "dln2-i2c",
> +		.platform_data = &dln2_pdata_i2c,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +};
> +
> +static bool dln2_all_rx_slots_free(struct dln2_mod_rx_slots *rxs)
> +{
> +	unsigned long flags;
> +	int slot;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +	slot = find_first_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (slot < DLN2_MAX_RX_SLOTS)
> +		return false;
> +
> +	return true;
> +}
> +
> +static void dln2_stop(struct dln2_dev *dln2)
> +{
> +	int i, j;
> +
> +	for (i = 0; i < DLN2_HANDLES; i++) {
> +		struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&rxs->lock, flags);
> +
> +		/* fail further alloc_rx_slot calls */
> +		rxs->disconnected = true;
> +
> +		/* cancel all response waiters */
> +		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
> +			struct dln2_rx_context *rxc = &rxs->slots[j];
> +
> +			if (rxc->connected) {
> +				rxc->urb = NULL;

Don't overload the meaning of urb. Check the disconnected flag were
needed.

Also what would prevent a racing completion handler from setting
rxc->urb again when you release the lock below?

> +				complete(&rxc->done);
> +			}
> +		}
> +		spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +		/* wait for callers to release all rx_slots */
> +		wait_event(rxs->wq, dln2_all_rx_slots_free(rxs));
> +	}
> +}
> +
> +static void dln2_disconnect(struct usb_interface *interface)
> +{
> +	struct dln2_dev *dln2 = usb_get_intfdata(interface);
> +

First set the disconnected flag directly here to prevent any new
transfers from starting.

> +	dln2_stop(dln2);

Then do all the completions (to speed things up somewhat).

Then wait for the transfer counter to reach 0.

> +	mfd_remove_devices(&interface->dev);
> +	dln2_free(dln2);
> +}
> +
> +static int dln2_probe(struct usb_interface *interface,
> +		      const struct usb_device_id *id)
> +{
> +	struct usb_host_interface *hostif = interface->cur_altsetting;
> +	struct device *dev = &interface->dev;
> +	struct dln2_dev *dln2;
> +	int ret;
> +	int i, j;
> +
> +	if (hostif->desc.bInterfaceNumber != 0 ||
> +	    hostif->desc.bNumEndpoints < 2)
> +		return -ENODEV;
> +
> +	dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
> +	if (!dln2)
> +		return -ENOMEM;
> +
> +	dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
> +	dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
> +	dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
> +	dln2->interface = interface;
> +	usb_set_intfdata(interface, dln2);
> +
> +	for (i = 0; i < DLN2_HANDLES; i++) {
> +		init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
> +		spin_lock_init(&dln2->mod_rx_slots[i].lock);
> +		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
> +			init_completion(&dln2->mod_rx_slots[i].slots[j].done);
> +	}
> +
> +	spin_lock_init(&dln2->rx_cb_lock);
> +	INIT_LIST_HEAD(&dln2->rx_cb_list);
> +
> +	ret = dln2_setup_rx_urbs(dln2, hostif);
> +	if (ret) {
> +		dln2_free(dln2);
> +		return ret;
> +	}
> +
> +	ret = dln2_hw_init(dln2);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to initialize hardware\n");
> +		goto out_cleanup;
> +	}
> +
> +	ret = mfd_add_devices(dev, -1, dln2_devs, ARRAY_SIZE(dln2_devs),

Use
	busnum << 8 | devnum

as id for now (as mentioned earlier).

> +			      NULL, 0, NULL);
> +	if (ret != 0) {
> +		dev_err(dev, "Failed to add mfd devices to core.\n");
> +		goto out_cleanup;
> +	}
> +
> +	return 0;
> +
> +out_cleanup:
> +	dln2_free(dln2);
> +
> +	return ret;
> +}

Johan
--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html