drivers/staging/greybus/es1-ap-usb.c - kernel/msm-4.9 - Gitiles

 /*
  * Greybus "AP" USB driver
  *
  * Copyright 2014 Google Inc.
  *
  * Released under the GPLv2 only.
  */
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/errno.h>
 #include <linux/sizes.h>
 #include <linux/usb.h>

 #include "greybus.h"
 #include "svc_msg.h"
 #include "kernel_ver.h"

 /* Memory sizes for the buffers sent to/from the ES1 controller */
 #define ES1_SVC_MSG_SIZE	(sizeof(struct svc_msg) + SZ_64K)
 #define ES1_GBUF_MSG_SIZE	PAGE_SIZE

 static const struct usb_device_id id_table[] = {
 	/* Made up numbers for the SVC USB Bridge in ES1 */
 	{ USB_DEVICE(0xffff, 0x0001) },
 	{ },
 };
 MODULE_DEVICE_TABLE(usb, id_table);

 /*
  * Number of CPort IN urbs in flight at any point in time.
  * Adjust if we are having stalls in the USB buffer due to not enough urbs in
  * flight.
  */
 #define NUM_CPORT_IN_URB	4

 /* Number of CPort OUT urbs in flight at any point in time.
  * Adjust if we get messages saying we are out of urbs in the system log.
  */
 #define NUM_CPORT_OUT_URB	8

 /**
  * es1_ap_dev - ES1 USB Bridge to AP structure
  * @usb_dev: pointer to the USB device we are.
  * @usb_intf: pointer to the USB interface we are bound to.
  * @hd: pointer to our greybus_host_device structure
  * @control_endpoint: endpoint to send data to SVC
  * @svc_endpoint: endpoint for SVC data in
  * @cport_in_endpoint: bulk in endpoint for CPort data
  * @cport-out_endpoint: bulk out endpoint for CPort data
  * @svc_buffer: buffer for SVC messages coming in on @svc_endpoint
  * @svc_urb: urb for SVC messages coming in on @svc_endpoint
  * @cport_in_urb: array of urbs for the CPort in messages
  * @cport_in_buffer: array of buffers for the @cport_in_urb urbs
  * @cport_out_urb: array of urbs for the CPort out messages
  * @cport_out_urb_busy: array of flags to see if the @cport_out_urb is busy or
  *			not.
  * @cport_out_urb_lock: locks the @cport_out_urb_busy "list"
  */
 struct es1_ap_dev {
 	struct usb_device *usb_dev;
 	struct usb_interface *usb_intf;
 	struct greybus_host_device *hd;

 	__u8 control_endpoint;
 	__u8 svc_endpoint;
 	__u8 cport_in_endpoint;
 	__u8 cport_out_endpoint;

 	u8 *svc_buffer;
 	struct urb *svc_urb;

 	struct urb *cport_in_urb[NUM_CPORT_IN_URB];
 	u8 *cport_in_buffer[NUM_CPORT_IN_URB];
 	struct urb *cport_out_urb[NUM_CPORT_OUT_URB];
 	bool cport_out_urb_busy[NUM_CPORT_OUT_URB];
 	spinlock_t cport_out_urb_lock;
 };

 static inline struct es1_ap_dev *hd_to_es1(struct greybus_host_device *hd)
 {
 	return (struct es1_ap_dev *)&hd->hd_priv;
 }

 static void cport_out_callback(struct urb *urb);

 /*
  * Allocate a buffer to be sent via UniPro.
  */
 static void *buffer_alloc(unsigned int size, gfp_t gfp_mask)
 {
 	u8 *buffer;

 	if (size > ES1_GBUF_MSG_SIZE) {
 		pr_err("guf was asked to be bigger than %ld!\n",
 		       ES1_GBUF_MSG_SIZE);
 	}

 	/*
 	 * For ES1 we need to insert a byte at the front of the data
 	 * to indicate the destination CPort id.  We only need one
 	 * extra byte, but we allocate four extra bytes to allow the
 	 * buffer returned to be aligned on a four-byte boundary.
 	 *
 	 * This is only needed for outbound data, but we handle
 	 * buffers for inbound data the same way for consistency.
 	 *
 	 * XXX Do we need to indicate the destination device id too?
 	 */
 	buffer = kzalloc(GB_BUFFER_ALIGN + size, gfp_mask);
 	if (buffer)
 		buffer += GB_BUFFER_ALIGN;

 	return buffer;
 }

 /* Free the memory we allocated with a gbuf */
 static void free_gbuf_data(struct gbuf *gbuf)
 {
 	u8 *transfer_buffer = gbuf->transfer_buffer;

 	/* Can be called with a NULL transfer_buffer on some error paths */
 	if (!transfer_buffer)
 		return;

 	/* Account for the space set aside for the prepended cport id */
 	transfer_buffer -= GB_BUFFER_ALIGN;
 	kfree(transfer_buffer);
 	gbuf->transfer_buffer = NULL;
 }

 #define ES1_TIMEOUT	500	/* 500 ms for the SVC to do something */
 static int submit_svc(struct svc_msg *svc_msg, struct greybus_host_device *hd)
 {
 	struct es1_ap_dev *es1 = hd_to_es1(hd);
 	int retval;

 	/* SVC messages go down our control pipe */
 	retval = usb_control_msg(es1->usb_dev,
 				 usb_sndctrlpipe(es1->usb_dev,
 						 es1->control_endpoint),
 				 0x01,	/* vendor request AP message */
 				 USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
 				 0x00, 0x00,
 				 (char *)svc_msg,
 				 sizeof(*svc_msg),
 				 ES1_TIMEOUT);
 	if (retval != sizeof(*svc_msg))
 		return retval;

 	return 0;
 }

 static struct urb *next_free_urb(struct es1_ap_dev *es1, gfp_t gfp_mask)
 {
 	struct urb *urb = NULL;
 	unsigned long flags;
 	int i;

 	spin_lock_irqsave(&es1->cport_out_urb_lock, flags);

 	/* Look in our pool of allocated urbs first, as that's the "fastest" */
 	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
 		if (es1->cport_out_urb_busy[i] == false) {
 			es1->cport_out_urb_busy[i] = true;
 			urb = es1->cport_out_urb[i];
 			break;
 		}
 	}
 	spin_unlock_irqrestore(&es1->cport_out_urb_lock, flags);
 	if (urb)
 		return urb;

 	/*
 	 * Crap, pool is empty, complain to the syslog and go allocate one
 	 * dynamically as we have to succeed.
 	 */
 	dev_err(&es1->usb_dev->dev,
 		"No free CPort OUT urbs, having to dynamically allocate one!\n");
 	urb = usb_alloc_urb(0, gfp_mask);
 	if (!urb)
 		return NULL;

 	return urb;
 }

 static int submit_gbuf(struct gbuf *gbuf, gfp_t gfp_mask)
 {
 	struct greybus_host_device *hd = gbuf->hd;
 	struct es1_ap_dev *es1 = hd_to_es1(hd);
 	struct usb_device *udev = es1->usb_dev;
 	u16 dest_cport_id = gbuf->dest_cport_id;
 	int retval;
 	u8 *transfer_buffer;
 	u8 *buffer;
 	struct urb *urb;

 	transfer_buffer = gbuf->transfer_buffer;
 	if (!transfer_buffer)
 		return -EINVAL;
 	buffer = &transfer_buffer[-1];	/* yes, we mean -1 */

 	/* Do one last check of the target CPort id before filling it in */
 	if (dest_cport_id == CPORT_ID_BAD) {
 		pr_err("request to send inbound data buffer\n");
 		return -EINVAL;
 	}
 	if (dest_cport_id > (u16)U8_MAX) {
 		pr_err("dest_cport_id (%hd) is out of range for ES1\n",
 			dest_cport_id);
 		return -EINVAL;
 	}
 	*buffer = dest_cport_id;

 	/* Find a free urb */
 	urb = next_free_urb(es1, gfp_mask);
 	if (!urb)
 		return -ENOMEM;

 	gbuf->hcd_data = urb;

 	usb_fill_bulk_urb(urb, udev,
 			  usb_sndbulkpipe(udev, es1->cport_out_endpoint),
 			  buffer, gbuf->transfer_buffer_length + 1,
 			  cport_out_callback, gbuf);
 	retval = usb_submit_urb(urb, gfp_mask);
 	return retval;
 }

 static void kill_gbuf(struct gbuf *gbuf)
 {
 	struct urb *urb = gbuf->hcd_data;

 	if (!urb)
 		return;

 	usb_kill_urb(urb);
 }

 static struct greybus_host_driver es1_driver = {
 	.hd_priv_size		= sizeof(struct es1_ap_dev),
 	.buffer_alloc		= buffer_alloc,
 	.free_gbuf_data		= free_gbuf_data,
 	.submit_svc		= submit_svc,
 	.submit_gbuf		= submit_gbuf,
 	.kill_gbuf		= kill_gbuf,
 };

 /* Common function to report consistent warnings based on URB status */
 static int check_urb_status(struct urb *urb)
 {
 	struct device *dev = &urb->dev->dev;
 	int status = urb->status;

 	switch (status) {
 	case 0:
 		return 0;

 	case -EOVERFLOW:
 		dev_err(dev, "%s: overflow actual length is %d\n",
 			__func__, urb->actual_length);
 	case -ECONNRESET:
 	case -ENOENT:
 	case -ESHUTDOWN:
 	case -EILSEQ:
 	case -EPROTO:
 		/* device is gone, stop sending */
 		return status;
 	}
 	dev_err(dev, "%s: unknown status %d\n", __func__, status);

 	return -EAGAIN;
 }

 static void ap_disconnect(struct usb_interface *interface)
 {
 	struct es1_ap_dev *es1;
 	int i;

 	es1 = usb_get_intfdata(interface);
 	if (!es1)
 		return;

 	/* Tear down everything! */
 	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
 		struct urb *urb = es1->cport_out_urb[i];

 		if (!urb)
 			break;
 		usb_kill_urb(urb);
 		usb_free_urb(urb);
 		es1->cport_out_urb[i] = NULL;
 		es1->cport_out_urb_busy[i] = false;	/* just to be anal */
 	}

 	for (i = 0; i < NUM_CPORT_IN_URB; ++i) {
 		struct urb *urb = es1->cport_in_urb[i];

 		if (!urb)
 			break;
 		usb_kill_urb(urb);
 		usb_free_urb(urb);
 		kfree(es1->cport_in_buffer[i]);
 		es1->cport_in_buffer[i] = NULL;
 	}

 	usb_kill_urb(es1->svc_urb);
 	usb_free_urb(es1->svc_urb);
 	es1->svc_urb = NULL;
 	kfree(es1->svc_buffer);
 	es1->svc_buffer = NULL;

 	usb_set_intfdata(interface, NULL);
 	greybus_remove_hd(es1->hd);

 	usb_put_dev(es1->usb_dev);
 }

 /* Callback for when we get a SVC message */
 static void svc_in_callback(struct urb *urb)
 {
 	struct es1_ap_dev *es1 = urb->context;
 	struct device *dev = &urb->dev->dev;
 	int status = check_urb_status(urb);
 	int retval;

 	if (status) {
 		if (status == -EAGAIN)
 			goto exit;
 		dev_err(dev, "urb svc in error %d (dropped)\n", status);
 		return;
 	}

 	/* We have a message, create a new message structure, add it to the
 	 * list, and wake up our thread that will process the messages.
 	 */
 	greybus_svc_in(es1->hd, urb->transfer_buffer, urb->actual_length);

 exit:
 	/* resubmit the urb to get more messages */
 	retval = usb_submit_urb(urb, GFP_ATOMIC);
 	if (retval)
 		dev_err(dev, "Can not submit urb for AP data: %d\n", retval);
 }

 static void cport_in_callback(struct urb *urb)
 {
 	struct device *dev = &urb->dev->dev;
 	struct es1_ap_dev *es1 = urb->context;
 	int status = check_urb_status(urb);
 	int retval;
 	u8 cport;
 	u8 *data;

 	if (status) {
 		if (status == -EAGAIN)
 			goto exit;
 		dev_err(dev, "urb cport in error %d (dropped)\n", status);
 		return;
 	}

 	/* The size has to be at least one, for the cport id */
 	if (!urb->actual_length) {
 		dev_err(dev, "%s: no cport id in input buffer?\n", __func__);
 		goto exit;
 	}

 	/*
 	 * The CPort number is the first byte of the data stream, the rest of
 	 * the stream is "real" data
 	 */
 	data = urb->transfer_buffer;
 	cport = data[0];
 	data = &data[1];

 	/* Pass this data to the greybus core */
 	greybus_cport_in(es1->hd, cport, data, urb->actual_length - 1);

 exit:
 	/* put our urb back in the request pool */
 	retval = usb_submit_urb(urb, GFP_ATOMIC);
 	if (retval)
 		dev_err(dev, "%s: error %d in submitting urb.\n",
 			__func__, retval);
 }

 static void cport_out_callback(struct urb *urb)
 {
 	struct gbuf *gbuf = urb->context;
 	struct es1_ap_dev *es1 = hd_to_es1(gbuf->hd);
 	unsigned long flags;
 	int i;

 	/* Record whether the transfer was successful */
 	gbuf->status = check_urb_status(urb);
 	gbuf->hcd_data = NULL;

 	/*
 	 * See if this was an urb in our pool, if so mark it "free", otherwise
 	 * we need to free it ourselves.
 	 */
 	spin_lock_irqsave(&es1->cport_out_urb_lock, flags);
 	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
 		if (urb == es1->cport_out_urb[i]) {
 			es1->cport_out_urb_busy[i] = false;
 			urb = NULL;
 			break;
 		}
 	}
 	spin_unlock_irqrestore(&es1->cport_out_urb_lock, flags);

 	/* If urb is not NULL, then we need to free this urb */
 	usb_free_urb(urb);

 	/*
 	 * Yes, you are right, we aren't telling anyone that the urb finished.
 	 * "That's crazy!  How does this all even work?" you might be saying.
 	 * The "magic" is the idea that greybus works on the "operation" level,
 	 * not the "send a buffer" level.  All operations are "round-trip" with
 	 * a response from the device that the operation finished, or it will
 	 * time out.  Because of that, we don't care that this urb finished, or
 	 * failed, or did anything else, as higher levels of the protocol stack
 	 * will handle completions and timeouts and the rest.
 	 *
 	 * This protocol is "needed" due to some hardware restrictions on the
 	 * current generation of Unipro controllers.  Think about it for a
 	 * minute, this is a USB driver, talking to a Unipro bridge, impediance
 	 * mismatch is huge, yet the Unipro controller are even more
 	 * underpowered than this little USB controller.  We rely on the round
 	 * trip to keep stalls in the Unipro controllers from happening so that
 	 * we can keep data flowing properly, no matter how slow it might be.
 	 *
 	 * Once again, a wonderful bus protocol cut down in its prime by a naive
 	 * controller chip.  We dream of the day we have a "real" HCD for
 	 * Unipro.  Until then, we suck it up and make the hardware work, as
 	 * that's the job of the firmware and kernel.
 	 * </rant>
 	 */
 }

 /*
  * The ES1 USB Bridge device contains 4 endpoints
  * 1 Control - usual USB stuff + AP -> SVC messages
  * 1 Interrupt IN - SVC -> AP messages
  * 1 Bulk IN - CPort data in
  * 1 Bulk OUT - CPort data out
  */
 static int ap_probe(struct usb_interface *interface,
 		    const struct usb_device_id *id)
 {
 	struct es1_ap_dev *es1;
 	struct greybus_host_device *hd;
 	struct usb_device *udev;
 	struct usb_host_interface *iface_desc;
 	struct usb_endpoint_descriptor *endpoint;
 	bool int_in_found = false;
 	bool bulk_in_found = false;
 	bool bulk_out_found = false;
 	int retval = -ENOMEM;
 	int i;
 	u8 svc_interval = 0;

 	udev = usb_get_dev(interface_to_usbdev(interface));

 	hd = greybus_create_hd(&es1_driver, &udev->dev);
 	if (!hd) {
 		usb_put_dev(udev);
 		return -ENOMEM;
 	}

 	es1 = hd_to_es1(hd);
 	es1->hd = hd;
 	es1->usb_intf = interface;
 	es1->usb_dev = udev;
 	spin_lock_init(&es1->cport_out_urb_lock);
 	usb_set_intfdata(interface, es1);

 	/* Control endpoint is the pipe to talk to this AP, so save it off */
 	endpoint = &udev->ep0.desc;
 	es1->control_endpoint = endpoint->bEndpointAddress;

 	/* find all 3 of our endpoints */
 	iface_desc = interface->cur_altsetting;
 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 		endpoint = &iface_desc->endpoint[i].desc;

 		if (usb_endpoint_is_int_in(endpoint)) {
 			es1->svc_endpoint = endpoint->bEndpointAddress;
 			svc_interval = endpoint->bInterval;
 			int_in_found = true;
 		} else if (usb_endpoint_is_bulk_in(endpoint)) {
 			es1->cport_in_endpoint = endpoint->bEndpointAddress;
 			bulk_in_found = true;
 		} else if (usb_endpoint_is_bulk_out(endpoint)) {
 			es1->cport_out_endpoint = endpoint->bEndpointAddress;
 			bulk_out_found = true;
 		} else {
 			dev_err(&udev->dev,
 				"Unknown endpoint type found, address %x\n",
 				endpoint->bEndpointAddress);
 		}
 	}
 	if ((int_in_found == false) ||
 	    (bulk_in_found == false) ||
 	    (bulk_out_found == false)) {
 		dev_err(&udev->dev, "Not enough endpoints found in device, aborting!\n");
 		goto error;
 	}

 	/* Create our buffer and URB to get SVC messages, and start it up */
 	es1->svc_buffer = kmalloc(ES1_SVC_MSG_SIZE, GFP_KERNEL);
 	if (!es1->svc_buffer)
 		goto error;

 	es1->svc_urb = usb_alloc_urb(0, GFP_KERNEL);
 	if (!es1->svc_urb)
 		goto error;

 	usb_fill_int_urb(es1->svc_urb, udev,
 			 usb_rcvintpipe(udev, es1->svc_endpoint),
 			 es1->svc_buffer, ES1_SVC_MSG_SIZE, svc_in_callback,
 			 es1, svc_interval);
 	retval = usb_submit_urb(es1->svc_urb, GFP_KERNEL);
 	if (retval)
 		goto error;

 	/* Allocate buffers for our cport in messages and start them up */
 	for (i = 0; i < NUM_CPORT_IN_URB; ++i) {
 		struct urb *urb;
 		u8 *buffer;

 		urb = usb_alloc_urb(0, GFP_KERNEL);
 		if (!urb)
 			goto error;
 		buffer = kmalloc(ES1_GBUF_MSG_SIZE, GFP_KERNEL);
 		if (!buffer)
 			goto error;

 		usb_fill_bulk_urb(urb, udev,
 				  usb_rcvbulkpipe(udev, es1->cport_in_endpoint),
 				  buffer, ES1_GBUF_MSG_SIZE, cport_in_callback,
 				  es1);
 		es1->cport_in_urb[i] = urb;
 		es1->cport_in_buffer[i] = buffer;
 		retval = usb_submit_urb(urb, GFP_KERNEL);
 		if (retval)
 			goto error;
 	}

 	/* Allocate urbs for our CPort OUT messages */
 	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
 		struct urb *urb;

 		urb = usb_alloc_urb(0, GFP_KERNEL);
 		if (!urb)
 			goto error;

 		es1->cport_out_urb[i] = urb;
 		es1->cport_out_urb_busy[i] = false;	/* just to be anal */
 	}

 	return 0;
 error:
 	ap_disconnect(interface);

 	return retval;
 }

 static struct usb_driver es1_ap_driver = {
 	.name =		"es1_ap_driver",
 	.probe =	ap_probe,
 	.disconnect =	ap_disconnect,
 	.id_table =	id_table,
 };

 module_usb_driver(es1_ap_driver);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Greg Kroah-Hartman <gregkh@linuxfoundation.org>");
	/*
	* Greybus "AP" USB driver
	*
	* Copyright 2014 Google Inc.
	*
	* Released under the GPLv2 only.
	*/
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/errno.h>
	#include <linux/sizes.h>
	#include <linux/usb.h>

	#include "greybus.h"
	#include "svc_msg.h"
	#include "kernel_ver.h"

	/* Memory sizes for the buffers sent to/from the ES1 controller */
	#define ES1_SVC_MSG_SIZE (sizeof(struct svc_msg) + SZ_64K)
	#define ES1_GBUF_MSG_SIZE PAGE_SIZE

	static const struct usb_device_id id_table[] = {
	/* Made up numbers for the SVC USB Bridge in ES1 */
	{ USB_DEVICE(0xffff, 0x0001) },
	{ },
	};
	MODULE_DEVICE_TABLE(usb, id_table);

	/*
	* Number of CPort IN urbs in flight at any point in time.
	* Adjust if we are having stalls in the USB buffer due to not enough urbs in
	* flight.
	*/
	#define NUM_CPORT_IN_URB 4

	/* Number of CPort OUT urbs in flight at any point in time.
	* Adjust if we get messages saying we are out of urbs in the system log.
	*/
	#define NUM_CPORT_OUT_URB 8

	/**
	* es1_ap_dev - ES1 USB Bridge to AP structure
	* @usb_dev: pointer to the USB device we are.
	* @usb_intf: pointer to the USB interface we are bound to.
	* @hd: pointer to our greybus_host_device structure
	* @control_endpoint: endpoint to send data to SVC
	* @svc_endpoint: endpoint for SVC data in
	* @cport_in_endpoint: bulk in endpoint for CPort data
	* @cport-out_endpoint: bulk out endpoint for CPort data
	* @svc_buffer: buffer for SVC messages coming in on @svc_endpoint
	* @svc_urb: urb for SVC messages coming in on @svc_endpoint
	* @cport_in_urb: array of urbs for the CPort in messages
	* @cport_in_buffer: array of buffers for the @cport_in_urb urbs
	* @cport_out_urb: array of urbs for the CPort out messages
	* @cport_out_urb_busy: array of flags to see if the @cport_out_urb is busy or
	* not.
	* @cport_out_urb_lock: locks the @cport_out_urb_busy "list"
	*/
	struct es1_ap_dev {
	struct usb_device *usb_dev;
	struct usb_interface *usb_intf;
	struct greybus_host_device *hd;

	__u8 control_endpoint;
	__u8 svc_endpoint;
	__u8 cport_in_endpoint;
	__u8 cport_out_endpoint;

	u8 *svc_buffer;
	struct urb *svc_urb;

	struct urb *cport_in_urb[NUM_CPORT_IN_URB];
	u8 *cport_in_buffer[NUM_CPORT_IN_URB];
	struct urb *cport_out_urb[NUM_CPORT_OUT_URB];
	bool cport_out_urb_busy[NUM_CPORT_OUT_URB];
	spinlock_t cport_out_urb_lock;
	};

	static inline struct es1_ap_dev hd_to_es1(struct greybus_host_device hd)
	{
	return (struct es1_ap_dev *)&hd->hd_priv;
	}

	static void cport_out_callback(struct urb *urb);

	/*
	* Allocate a buffer to be sent via UniPro.
	*/
	static void *buffer_alloc(unsigned int size, gfp_t gfp_mask)
	{
	u8 *buffer;

	if (size > ES1_GBUF_MSG_SIZE) {
	pr_err("guf was asked to be bigger than %ld!\n",
	ES1_GBUF_MSG_SIZE);
	}

	/*
	* For ES1 we need to insert a byte at the front of the data
	* to indicate the destination CPort id. We only need one
	* extra byte, but we allocate four extra bytes to allow the
	* buffer returned to be aligned on a four-byte boundary.
	*
	* This is only needed for outbound data, but we handle
	* buffers for inbound data the same way for consistency.
	*
	* XXX Do we need to indicate the destination device id too?
	*/
	buffer = kzalloc(GB_BUFFER_ALIGN + size, gfp_mask);
	if (buffer)
	buffer += GB_BUFFER_ALIGN;

	return buffer;
	}

	/* Free the memory we allocated with a gbuf */
	static void free_gbuf_data(struct gbuf *gbuf)
	{
	u8 *transfer_buffer = gbuf->transfer_buffer;

	/* Can be called with a NULL transfer_buffer on some error paths */
	if (!transfer_buffer)
	return;

	/* Account for the space set aside for the prepended cport id */
	transfer_buffer -= GB_BUFFER_ALIGN;
	kfree(transfer_buffer);
	gbuf->transfer_buffer = NULL;
	}

	#define ES1_TIMEOUT 500 /* 500 ms for the SVC to do something */
	static int submit_svc(struct svc_msg svc_msg, struct greybus_host_device hd)
	{
	struct es1_ap_dev *es1 = hd_to_es1(hd);
	int retval;

	/* SVC messages go down our control pipe */
	retval = usb_control_msg(es1->usb_dev,
	usb_sndctrlpipe(es1->usb_dev,
	es1->control_endpoint),
	0x01, /* vendor request AP message */
	USB_DIR_OUT \| USB_TYPE_VENDOR \| USB_RECIP_INTERFACE,
	0x00, 0x00,
	(char *)svc_msg,
	sizeof(*svc_msg),
	ES1_TIMEOUT);
	if (retval != sizeof(*svc_msg))
	return retval;

	return 0;
	}

	static struct urb next_free_urb(struct es1_ap_dev es1, gfp_t gfp_mask)
	{
	struct urb *urb = NULL;
	unsigned long flags;
	int i;

	spin_lock_irqsave(&es1->cport_out_urb_lock, flags);

	/* Look in our pool of allocated urbs first, as that's the "fastest" */
	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
	if (es1->cport_out_urb_busy[i] == false) {
	es1->cport_out_urb_busy[i] = true;
	urb = es1->cport_out_urb[i];
	break;
	}
	}
	spin_unlock_irqrestore(&es1->cport_out_urb_lock, flags);
	if (urb)
	return urb;

	/*
	* Crap, pool is empty, complain to the syslog and go allocate one
	* dynamically as we have to succeed.
	*/
	dev_err(&es1->usb_dev->dev,
	"No free CPort OUT urbs, having to dynamically allocate one!\n");
	urb = usb_alloc_urb(0, gfp_mask);
	if (!urb)
	return NULL;

	return urb;
	}

	static int submit_gbuf(struct gbuf *gbuf, gfp_t gfp_mask)
	{
	struct greybus_host_device *hd = gbuf->hd;
	struct es1_ap_dev *es1 = hd_to_es1(hd);
	struct usb_device *udev = es1->usb_dev;
	u16 dest_cport_id = gbuf->dest_cport_id;
	int retval;
	u8 *transfer_buffer;
	u8 *buffer;
	struct urb *urb;

	transfer_buffer = gbuf->transfer_buffer;
	if (!transfer_buffer)
	return -EINVAL;
	buffer = &transfer_buffer[-1]; /* yes, we mean -1 */

	/* Do one last check of the target CPort id before filling it in */
	if (dest_cport_id == CPORT_ID_BAD) {
	pr_err("request to send inbound data buffer\n");
	return -EINVAL;
	}
	if (dest_cport_id > (u16)U8_MAX) {
	pr_err("dest_cport_id (%hd) is out of range for ES1\n",
	dest_cport_id);
	return -EINVAL;
	}
	*buffer = dest_cport_id;

	/* Find a free urb */
	urb = next_free_urb(es1, gfp_mask);
	if (!urb)
	return -ENOMEM;

	gbuf->hcd_data = urb;

	usb_fill_bulk_urb(urb, udev,
	usb_sndbulkpipe(udev, es1->cport_out_endpoint),
	buffer, gbuf->transfer_buffer_length + 1,
	cport_out_callback, gbuf);
	retval = usb_submit_urb(urb, gfp_mask);
	return retval;
	}

	static void kill_gbuf(struct gbuf *gbuf)
	{
	struct urb *urb = gbuf->hcd_data;

	if (!urb)
	return;

	usb_kill_urb(urb);
	}

	static struct greybus_host_driver es1_driver = {
	.hd_priv_size = sizeof(struct es1_ap_dev),
	.buffer_alloc = buffer_alloc,
	.free_gbuf_data = free_gbuf_data,
	.submit_svc = submit_svc,
	.submit_gbuf = submit_gbuf,
	.kill_gbuf = kill_gbuf,
	};

	/* Common function to report consistent warnings based on URB status */
	static int check_urb_status(struct urb *urb)
	{
	struct device *dev = &urb->dev->dev;
	int status = urb->status;

	switch (status) {
	case 0:
	return 0;

	case -EOVERFLOW:
	dev_err(dev, "%s: overflow actual length is %d\n",
	__func__, urb->actual_length);
	case -ECONNRESET:
	case -ENOENT:
	case -ESHUTDOWN:
	case -EILSEQ:
	case -EPROTO:
	/* device is gone, stop sending */
	return status;
	}
	dev_err(dev, "%s: unknown status %d\n", __func__, status);

	return -EAGAIN;
	}

	static void ap_disconnect(struct usb_interface *interface)
	{
	struct es1_ap_dev *es1;
	int i;

	es1 = usb_get_intfdata(interface);
	if (!es1)
	return;

	/* Tear down everything! */
	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
	struct urb *urb = es1->cport_out_urb[i];

	if (!urb)
	break;
	usb_kill_urb(urb);
	usb_free_urb(urb);
	es1->cport_out_urb[i] = NULL;
	es1->cport_out_urb_busy[i] = false; /* just to be anal */
	}

	for (i = 0; i < NUM_CPORT_IN_URB; ++i) {
	struct urb *urb = es1->cport_in_urb[i];

	if (!urb)
	break;
	usb_kill_urb(urb);
	usb_free_urb(urb);
	kfree(es1->cport_in_buffer[i]);
	es1->cport_in_buffer[i] = NULL;
	}

	usb_kill_urb(es1->svc_urb);
	usb_free_urb(es1->svc_urb);
	es1->svc_urb = NULL;
	kfree(es1->svc_buffer);
	es1->svc_buffer = NULL;

	usb_set_intfdata(interface, NULL);
	greybus_remove_hd(es1->hd);

	usb_put_dev(es1->usb_dev);
	}

	/* Callback for when we get a SVC message */
	static void svc_in_callback(struct urb *urb)
	{
	struct es1_ap_dev *es1 = urb->context;
	struct device *dev = &urb->dev->dev;
	int status = check_urb_status(urb);
	int retval;

	if (status) {
	if (status == -EAGAIN)
	goto exit;
	dev_err(dev, "urb svc in error %d (dropped)\n", status);
	return;
	}

	/* We have a message, create a new message structure, add it to the
	* list, and wake up our thread that will process the messages.
	*/
	greybus_svc_in(es1->hd, urb->transfer_buffer, urb->actual_length);

	exit:
	/* resubmit the urb to get more messages */
	retval = usb_submit_urb(urb, GFP_ATOMIC);
	if (retval)
	dev_err(dev, "Can not submit urb for AP data: %d\n", retval);
	}

	static void cport_in_callback(struct urb *urb)
	{
	struct device *dev = &urb->dev->dev;
	struct es1_ap_dev *es1 = urb->context;
	int status = check_urb_status(urb);
	int retval;
	u8 cport;
	u8 *data;

	if (status) {
	if (status == -EAGAIN)
	goto exit;
	dev_err(dev, "urb cport in error %d (dropped)\n", status);
	return;
	}

	/* The size has to be at least one, for the cport id */
	if (!urb->actual_length) {
	dev_err(dev, "%s: no cport id in input buffer?\n", __func__);
	goto exit;
	}

	/*
	* The CPort number is the first byte of the data stream, the rest of
	* the stream is "real" data
	*/
	data = urb->transfer_buffer;
	cport = data[0];
	data = &data[1];

	/* Pass this data to the greybus core */
	greybus_cport_in(es1->hd, cport, data, urb->actual_length - 1);

	exit:
	/* put our urb back in the request pool */
	retval = usb_submit_urb(urb, GFP_ATOMIC);
	if (retval)
	dev_err(dev, "%s: error %d in submitting urb.\n",
	__func__, retval);
	}

	static void cport_out_callback(struct urb *urb)
	{
	struct gbuf *gbuf = urb->context;
	struct es1_ap_dev *es1 = hd_to_es1(gbuf->hd);
	unsigned long flags;
	int i;

	/* Record whether the transfer was successful */
	gbuf->status = check_urb_status(urb);
	gbuf->hcd_data = NULL;

	/*
	* See if this was an urb in our pool, if so mark it "free", otherwise
	* we need to free it ourselves.
	*/
	spin_lock_irqsave(&es1->cport_out_urb_lock, flags);
	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
	if (urb == es1->cport_out_urb[i]) {
	es1->cport_out_urb_busy[i] = false;
	urb = NULL;
	break;
	}
	}
	spin_unlock_irqrestore(&es1->cport_out_urb_lock, flags);

	/* If urb is not NULL, then we need to free this urb */
	usb_free_urb(urb);

	/*
	* Yes, you are right, we aren't telling anyone that the urb finished.
	* "That's crazy! How does this all even work?" you might be saying.
	* The "magic" is the idea that greybus works on the "operation" level,
	* not the "send a buffer" level. All operations are "round-trip" with
	* a response from the device that the operation finished, or it will
	* time out. Because of that, we don't care that this urb finished, or
	* failed, or did anything else, as higher levels of the protocol stack
	* will handle completions and timeouts and the rest.
	*
	* This protocol is "needed" due to some hardware restrictions on the
	* current generation of Unipro controllers. Think about it for a
	* minute, this is a USB driver, talking to a Unipro bridge, impediance
	* mismatch is huge, yet the Unipro controller are even more
	* underpowered than this little USB controller. We rely on the round
	* trip to keep stalls in the Unipro controllers from happening so that
	* we can keep data flowing properly, no matter how slow it might be.
	*
	* Once again, a wonderful bus protocol cut down in its prime by a naive
	* controller chip. We dream of the day we have a "real" HCD for
	* Unipro. Until then, we suck it up and make the hardware work, as
	* that's the job of the firmware and kernel.
	* </rant>
	*/
	}

	/*
	* The ES1 USB Bridge device contains 4 endpoints
	* 1 Control - usual USB stuff + AP -> SVC messages
	* 1 Interrupt IN - SVC -> AP messages
	* 1 Bulk IN - CPort data in
	* 1 Bulk OUT - CPort data out
	*/
	static int ap_probe(struct usb_interface *interface,
	const struct usb_device_id *id)
	{
	struct es1_ap_dev *es1;
	struct greybus_host_device *hd;
	struct usb_device *udev;
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;
	bool int_in_found = false;
	bool bulk_in_found = false;
	bool bulk_out_found = false;
	int retval = -ENOMEM;
	int i;
	u8 svc_interval = 0;

	udev = usb_get_dev(interface_to_usbdev(interface));

	hd = greybus_create_hd(&es1_driver, &udev->dev);
	if (!hd) {
	usb_put_dev(udev);
	return -ENOMEM;
	}

	es1 = hd_to_es1(hd);
	es1->hd = hd;
	es1->usb_intf = interface;
	es1->usb_dev = udev;
	spin_lock_init(&es1->cport_out_urb_lock);
	usb_set_intfdata(interface, es1);

	/* Control endpoint is the pipe to talk to this AP, so save it off */
	endpoint = &udev->ep0.desc;
	es1->control_endpoint = endpoint->bEndpointAddress;

	/* find all 3 of our endpoints */
	iface_desc = interface->cur_altsetting;
	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
	endpoint = &iface_desc->endpoint[i].desc;

	if (usb_endpoint_is_int_in(endpoint)) {
	es1->svc_endpoint = endpoint->bEndpointAddress;
	svc_interval = endpoint->bInterval;
	int_in_found = true;
	} else if (usb_endpoint_is_bulk_in(endpoint)) {
	es1->cport_in_endpoint = endpoint->bEndpointAddress;
	bulk_in_found = true;
	} else if (usb_endpoint_is_bulk_out(endpoint)) {
	es1->cport_out_endpoint = endpoint->bEndpointAddress;
	bulk_out_found = true;
	} else {
	dev_err(&udev->dev,
	"Unknown endpoint type found, address %x\n",
	endpoint->bEndpointAddress);
	}
	}
	if ((int_in_found == false) \|\|
	(bulk_in_found == false) \|\|
	(bulk_out_found == false)) {
	dev_err(&udev->dev, "Not enough endpoints found in device, aborting!\n");
	goto error;
	}

	/* Create our buffer and URB to get SVC messages, and start it up */
	es1->svc_buffer = kmalloc(ES1_SVC_MSG_SIZE, GFP_KERNEL);
	if (!es1->svc_buffer)
	goto error;

	es1->svc_urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!es1->svc_urb)
	goto error;

	usb_fill_int_urb(es1->svc_urb, udev,
	usb_rcvintpipe(udev, es1->svc_endpoint),
	es1->svc_buffer, ES1_SVC_MSG_SIZE, svc_in_callback,
	es1, svc_interval);
	retval = usb_submit_urb(es1->svc_urb, GFP_KERNEL);
	if (retval)
	goto error;

	/* Allocate buffers for our cport in messages and start them up */
	for (i = 0; i < NUM_CPORT_IN_URB; ++i) {
	struct urb *urb;
	u8 *buffer;

	urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!urb)
	goto error;
	buffer = kmalloc(ES1_GBUF_MSG_SIZE, GFP_KERNEL);
	if (!buffer)
	goto error;

	usb_fill_bulk_urb(urb, udev,
	usb_rcvbulkpipe(udev, es1->cport_in_endpoint),
	buffer, ES1_GBUF_MSG_SIZE, cport_in_callback,
	es1);
	es1->cport_in_urb[i] = urb;
	es1->cport_in_buffer[i] = buffer;
	retval = usb_submit_urb(urb, GFP_KERNEL);
	if (retval)
	goto error;
	}

	/* Allocate urbs for our CPort OUT messages */
	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
	struct urb *urb;

	urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!urb)
	goto error;

	es1->cport_out_urb[i] = urb;
	es1->cport_out_urb_busy[i] = false; /* just to be anal */
	}

	return 0;
	error:
	ap_disconnect(interface);

	return retval;
	}

	static struct usb_driver es1_ap_driver = {
	.name = "es1_ap_driver",
	.probe = ap_probe,
	.disconnect = ap_disconnect,
	.id_table = id_table,
	};

	module_usb_driver(es1_ap_driver);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Greg Kroah-Hartman <gregkh@linuxfoundation.org>");