USB: gadget: f_accessory: Add new gadget driver for android USB accesories.

arch/arm/configs/htcleo_defconfig

@@ -1435,6 +1435,7 @@ CONFIG_USB_ANDROID_DIAG=y
 CONFIG_USB_ANDROID_MASS_STORAGE=y
 CONFIG_USB_ANDROID_RNDIS=y
 CONFIG_USB_ANDROID_RNDIS_WCEIS=y
+CONFIG_USB_ANDROID_ACCESSORY=y
 CONFIG_USB_ANDROID_SERIAL=y
 # CONFIG_USB_ANDROID_PROJECTOR is not set
 # CONFIG_USB_ANDROID_MTP is not set

arch/arm/mach-msm/include/mach/htc_usb.h

@@ -16,6 +16,7 @@
 
 #ifdef CONFIG_USB_ANDROID
 #include <linux/usb/android_composite.h>
+#include <linux/usb/f_accessory.h>
 
 #ifdef CONFIG_ARCH_QSD8X50
 void msm_hsusb_8x50_phy_reset(void);
@@ -40,6 +41,16 @@ static char *usb_functions_rndis_adb[] = {
 };
 #endif
 
+#ifdef CONFIG_USB_ANDROID_ACCESSORY
+static char *usb_functions_accessory[] = {
+	"accessory"
+};
+static char *usb_functions_accessory_adb[] = {
+	"accessory",
+	"adb"
+};
+#endif
+
 #ifdef CONFIG_USB_ANDROID_PROJECTOR
 static char *usb_functions_projector[] = {
 	"usb_mass_storage",
@@ -116,6 +127,9 @@ static char *usb_functions_all[] = {
 #ifdef CONFIG_USB_ANDROID_RNDIS
 	"rndis",
 #endif
+#ifdef CONFIG_USB_ANDROID_ACCESSORY
+	"accessory",
+#endif
 #ifdef CONFIG_USB_ANDROID_MTP
 	"mtp",
 #endif
@@ -225,6 +239,20 @@ static struct android_usb_product usb_products[] = {
 		.functions	= usb_functions_rndis_adb,
 	},
 #endif
+#ifdef CONFIG_USB_ANDROID_ACCESSORY
+	{
+		.vendor_id	= USB_ACCESSORY_VENDOR_ID,
+		.product_id	= USB_ACCESSORY_PRODUCT_ID,
+		.num_functions	= ARRAY_SIZE(usb_functions_accessory),
+		.functions	= usb_functions_accessory,
+	},
+	{
+		.vendor_id	= USB_ACCESSORY_VENDOR_ID,
+		.product_id	= USB_ACCESSORY_ADB_PRODUCT_ID,
+		.num_functions	= ARRAY_SIZE(usb_functions_accessory_adb),
+		.functions	= usb_functions_accessory_adb,
+	},
+#endif
 };
 #endif
 

drivers/usb/gadget/Kconfig

@@ -845,6 +845,12 @@ config USB_ANDROID_RNDIS_WCEIS
          If you enable this option, the device is no longer CDC ethernet
          compatible.
 
+config USB_ANDROID_ACCESSORY
+        boolean "Android USB accessory function"
+        depends on USB_ANDROID
+        help
+         Provides Android USB Accessory support for android gadget driver.
+
 config USB_ANDROID_SERIAL
 	boolean "Android gadget Serial function"
 	depends on USB_ANDROID

drivers/usb/gadget/Makefile

@@ -58,6 +58,7 @@ obj-$(CONFIG_USB_ANDROID_ACM)	+= f_acm.o u_serial.o
 obj-$(CONFIG_USB_ANDROID_ADB)	+= f_adb.o
 obj-$(CONFIG_USB_ANDROID_MASS_STORAGE)	+= f_mass_storage.o
 obj-$(CONFIG_USB_ANDROID_RNDIS)	+= f_rndis.o u_ether.o
+obj-$(CONFIG_USB_ANDROID_ACCESSORY)	+= f_accessory.o
 obj-$(CONFIG_USB_ANDROID_SERIAL)	+= serial.o u_serial.o
 obj-$(CONFIG_USB_ANDROID_PROJECTOR)	+= f_projector.o
 obj-$(CONFIG_USB_ANDROID_MTP)	+= f_mtp.o

drivers/usb/gadget/android.c

@@ -527,6 +527,20 @@ void android_enable_function(struct usb_function *f, int enable)
 			}
 		}
 #endif
+#ifdef CONFIG_USB_ANDROID_ACCESSORY
+		if (!strcmp(f->name, "accessory") && enable) {
+			struct usb_function		*func;
+
+			/* disable everything else (and keep adb for now) */
+			list_for_each_entry(func, &android_config_driver.functions, list) {
+				if (strcmp(func->name, "accessory")
+					&& strcmp(func->name, "adb")) {
+					f->hidden = enable;
+					break;
+				}
+			}
+		}
+#endif
 
 		product_id = get_product_id(dev);
 		device_desc.idProduct = __constant_cpu_to_le16(product_id);

drivers/usb/gadget/f_accessory.c

@@ -0,0 +1,808 @@
+/*
+ * Gadget Function Driver for Android USB accessories
+ *
+ * Copyright (C) 2011 Google, Inc.
+ * Author: Mike Lockwood <lockwood@android.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+/* #define DEBUG */
+/* #define VERBOSE_DEBUG */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/delay.h>
+#include <linux/wait.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+
+#include <linux/types.h>
+#include <linux/file.h>
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+
+#include <linux/usb.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/android_composite.h>
+#include <linux/usb/f_accessory.h>
+
+#define BULK_BUFFER_SIZE    16384
+#define ACC_STRING_SIZE     256
+
+#define PROTOCOL_VERSION    1
+
+/* String IDs */
+#define INTERFACE_STRING_INDEX	0
+
+/* number of tx and rx requests to allocate */
+#define TX_REQ_MAX 4
+#define RX_REQ_MAX 2
+
+struct acc_dev {
+	struct usb_function function;
+	struct usb_composite_dev *cdev;
+	spinlock_t lock;
+
+	struct usb_ep *ep_in;
+	struct usb_ep *ep_out;
+
+	/* set to 1 when we connect */
+	int online:1;
+	/* Set to 1 when we disconnect.
+	 * Not cleared until our file is closed.
+	 */
+	int disconnected:1;
+
+	/* strings sent by the host */
+	char manufacturer[ACC_STRING_SIZE];
+	char model[ACC_STRING_SIZE];
+	char description[ACC_STRING_SIZE];
+	char version[ACC_STRING_SIZE];
+	char uri[ACC_STRING_SIZE];
+	char serial[ACC_STRING_SIZE];
+
+	/* for acc_complete_set_string */
+	int string_index;
+
+	/* synchronize access to our device file */
+	atomic_t open_excl;
+
+	struct list_head tx_idle;
+
+	wait_queue_head_t read_wq;
+	wait_queue_head_t write_wq;
+	struct usb_request *rx_req[RX_REQ_MAX];
+	int rx_done;
+	struct delayed_work work;
+};
+
+static struct usb_interface_descriptor acc_interface_desc = {
+	.bLength                = USB_DT_INTERFACE_SIZE,
+	.bDescriptorType        = USB_DT_INTERFACE,
+	.bInterfaceNumber       = 0,
+	.bNumEndpoints          = 3,
+	.bInterfaceClass        = USB_CLASS_VENDOR_SPEC,
+	.bInterfaceSubClass     = USB_SUBCLASS_VENDOR_SPEC,
+	.bInterfaceProtocol     = 0,
+};
+
+static struct usb_endpoint_descriptor acc_highspeed_in_desc = {
+	.bLength                = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType        = USB_DT_ENDPOINT,
+	.bEndpointAddress       = USB_DIR_IN,
+	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize         = __constant_cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor acc_highspeed_out_desc = {
+	.bLength                = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType        = USB_DT_ENDPOINT,
+	.bEndpointAddress       = USB_DIR_OUT,
+	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize         = __constant_cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor acc_fullspeed_in_desc = {
+	.bLength                = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType        = USB_DT_ENDPOINT,
+	.bEndpointAddress       = USB_DIR_IN,
+	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor acc_fullspeed_out_desc = {
+	.bLength                = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType        = USB_DT_ENDPOINT,
+	.bEndpointAddress       = USB_DIR_OUT,
+	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *fs_acc_descs[] = {
+	(struct usb_descriptor_header *) &acc_interface_desc,
+	(struct usb_descriptor_header *) &acc_fullspeed_in_desc,
+	(struct usb_descriptor_header *) &acc_fullspeed_out_desc,
+	NULL,
+};
+
+static struct usb_descriptor_header *hs_acc_descs[] = {
+	(struct usb_descriptor_header *) &acc_interface_desc,
+	(struct usb_descriptor_header *) &acc_highspeed_in_desc,
+	(struct usb_descriptor_header *) &acc_highspeed_out_desc,
+	NULL,
+};
+
+static struct usb_string acc_string_defs[] = {
+	[INTERFACE_STRING_INDEX].s	= "Android Accessory Interface",
+	{  },	/* end of list */
+};
+
+static struct usb_gadget_strings acc_string_table = {
+	.language		= 0x0409,	/* en-US */
+	.strings		= acc_string_defs,
+};
+
+static struct usb_gadget_strings *acc_strings[] = {
+	&acc_string_table,
+	NULL,
+};
+
+/* temporary variable used between acc_open() and acc_gadget_bind() */
+static struct acc_dev *_acc_dev;
+
+static inline struct acc_dev *func_to_dev(struct usb_function *f)
+{
+	return container_of(f, struct acc_dev, function);
+}
+
+static struct usb_request *acc_request_new(struct usb_ep *ep, int buffer_size)
+{
+	struct usb_request *req = usb_ep_alloc_request(ep, GFP_KERNEL);
+	if (!req)
+		return NULL;
+
+	/* now allocate buffers for the requests */
+	req->buf = kmalloc(buffer_size, GFP_KERNEL);
+	if (!req->buf) {
+		usb_ep_free_request(ep, req);
+		return NULL;
+	}
+
+	return req;
+}
+
+static void acc_request_free(struct usb_request *req, struct usb_ep *ep)
+{
+	if (req) {
+		kfree(req->buf);
+		usb_ep_free_request(ep, req);
+	}
+}
+
+/* add a request to the tail of a list */
+static void req_put(struct acc_dev *dev, struct list_head *head,
+		struct usb_request *req)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	list_add_tail(&req->list, head);
+	spin_unlock_irqrestore(&dev->lock, flags);
+}
+
+/* remove a request from the head of a list */
+static struct usb_request *req_get(struct acc_dev *dev, struct list_head *head)
+{
+	unsigned long flags;
+	struct usb_request *req;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (list_empty(head)) {
+		req = 0;
+	} else {
+		req = list_first_entry(head, struct usb_request, list);
+		list_del(&req->list);
+	}
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return req;
+}
+
+static void acc_set_disconnected(struct acc_dev *dev)
+{
+	dev->online = 0;
+	dev->disconnected = 1;
+}
+
+static void acc_complete_in(struct usb_ep *ep, struct usb_request *req)
+{
+	struct acc_dev *dev = _acc_dev;
+
+	if (req->status != 0)
+		acc_set_disconnected(dev);
+
+	req_put(dev, &dev->tx_idle, req);
+
+	wake_up(&dev->write_wq);
+}
+
+static void acc_complete_out(struct usb_ep *ep, struct usb_request *req)
+{
+	struct acc_dev *dev = _acc_dev;
+
+	dev->rx_done = 1;
+	if (req->status != 0)
+		acc_set_disconnected(dev);
+
+	wake_up(&dev->read_wq);
+}
+
+static void acc_complete_set_string(struct usb_ep *ep, struct usb_request *req)
+{
+	struct acc_dev	*dev = ep->driver_data;
+	struct usb_composite_dev *cdev = dev->cdev;
+	char *string_dest = NULL;
+	int length = req->actual;
+
+	if (req->status != 0) {
+		DBG(cdev, "acc_complete_set_string, err %d\n", req->status);
+		return;
+	}
+
+	switch (dev->string_index) {
+	case ACCESSORY_STRING_MANUFACTURER:
+		string_dest = dev->manufacturer;
+		break;
+	case ACCESSORY_STRING_MODEL:
+		string_dest = dev->model;
+		break;
+	case ACCESSORY_STRING_DESCRIPTION:
+		string_dest = dev->description;
+		break;
+	case ACCESSORY_STRING_VERSION:
+		string_dest = dev->version;
+		break;
+	case ACCESSORY_STRING_URI:
+		string_dest = dev->uri;
+		break;
+	case ACCESSORY_STRING_SERIAL:
+		string_dest = dev->serial;
+		break;
+	}
+	if (string_dest) {
+		unsigned long flags;
+
+		if (length >= ACC_STRING_SIZE)
+			length = ACC_STRING_SIZE - 1;
+
+		spin_lock_irqsave(&dev->lock, flags);
+		memcpy(string_dest, cdev->req->buf, length);
+		/* ensure zero termination */
+		string_dest[length] = 0;
+		spin_unlock_irqrestore(&dev->lock, flags);
+	} else {
+		DBG(cdev, "unknown accessory string index %d\n",
+			dev->string_index);
+	}
+}
+
+static int __init create_bulk_endpoints(struct acc_dev *dev,
+				struct usb_endpoint_descriptor *in_desc,
+				struct usb_endpoint_descriptor *out_desc)
+{
+	struct usb_composite_dev *cdev = dev->cdev;
+	struct usb_request *req;
+	struct usb_ep *ep;
+	int i;
+
+	DBG(cdev, "create_bulk_endpoints dev: %p\n", dev);
+
+	ep = usb_ep_autoconfig(cdev->gadget, in_desc);
+	if (!ep) {
+		DBG(cdev, "usb_ep_autoconfig for ep_in failed\n");
+		return -ENODEV;
+	}
+	DBG(cdev, "usb_ep_autoconfig for ep_in got %s\n", ep->name);
+	ep->driver_data = dev;		/* claim the endpoint */
+	dev->ep_in = ep;
+
+	ep = usb_ep_autoconfig(cdev->gadget, out_desc);
+	if (!ep) {
+		DBG(cdev, "usb_ep_autoconfig for ep_out failed\n");
+		return -ENODEV;
+	}
+	DBG(cdev, "usb_ep_autoconfig for ep_out got %s\n", ep->name);
+	ep->driver_data = dev;		/* claim the endpoint */
+	dev->ep_out = ep;
+
+	ep = usb_ep_autoconfig(cdev->gadget, out_desc);
+	if (!ep) {
+		DBG(cdev, "usb_ep_autoconfig for ep_out failed\n");
+		return -ENODEV;
+	}
+	DBG(cdev, "usb_ep_autoconfig for ep_out got %s\n", ep->name);
+	ep->driver_data = dev;		/* claim the endpoint */
+	dev->ep_out = ep;
+
+	/* now allocate requests for our endpoints */
+	for (i = 0; i < TX_REQ_MAX; i++) {
+		req = acc_request_new(dev->ep_in, BULK_BUFFER_SIZE);
+		if (!req)
+			goto fail;
+		req->complete = acc_complete_in;
+		req_put(dev, &dev->tx_idle, req);
+	}
+	for (i = 0; i < RX_REQ_MAX; i++) {
+		req = acc_request_new(dev->ep_out, BULK_BUFFER_SIZE);
+		if (!req)
+			goto fail;
+		req->complete = acc_complete_out;
+		dev->rx_req[i] = req;
+	}
+
+	return 0;
+
+fail:
+	printk(KERN_ERR "acc_bind() could not allocate requests\n");
+	while ((req = req_get(dev, &dev->tx_idle)))
+		acc_request_free(req, dev->ep_in);
+	for (i = 0; i < RX_REQ_MAX; i++)
+		acc_request_free(dev->rx_req[i], dev->ep_out);
+	return -1;
+}
+
+static ssize_t acc_read(struct file *fp, char __user *buf,
+	size_t count, loff_t *pos)
+{
+	struct acc_dev *dev = fp->private_data;
+	struct usb_composite_dev *cdev = dev->cdev;
+	struct usb_request *req;
+	int r = count, xfer;
+	int ret = 0;
+
+	DBG(cdev, "acc_read(%d)\n", count);
+
+	if (dev->disconnected)
+		return -ENODEV;
+
+	if (count > BULK_BUFFER_SIZE)
+		count = BULK_BUFFER_SIZE;
+
+	/* we will block until we're online */
+	DBG(cdev, "acc_read: waiting for online\n");
+	ret = wait_event_interruptible(dev->read_wq, dev->online);
+	if (ret < 0) {
+		r = ret;
+		goto done;
+	}
+
+requeue_req:
+	/* queue a request */
+	req = dev->rx_req[0];
+	req->length = count;
+	dev->rx_done = 0;
+	ret = usb_ep_queue(dev->ep_out, req, GFP_KERNEL);
+	if (ret < 0) {
+		r = -EIO;
+		goto done;
+	} else {
+		DBG(cdev, "rx %p queue\n", req);
+	}
+
+	/* wait for a request to complete */
+	ret = wait_event_interruptible(dev->read_wq, dev->rx_done);
+	if (ret < 0) {
+		r = ret;
+		usb_ep_dequeue(dev->ep_out, req);
+		goto done;
+	}
+	if (dev->online) {
+		/* If we got a 0-len packet, throw it back and try again. */
+		if (req->actual == 0)
+			goto requeue_req;
+
+		DBG(cdev, "rx %p %d\n", req, req->actual);
+		xfer = (req->actual < count) ? req->actual : count;
+		r = xfer;
+		if (copy_to_user(buf, req->buf, xfer))
+			r = -EFAULT;
+	} else
+		r = -EIO;
+
+done:
+	DBG(cdev, "acc_read returning %d\n", r);
+	return r;
+}
+
+static ssize_t acc_write(struct file *fp, const char __user *buf,
+	size_t count, loff_t *pos)
+{
+	struct acc_dev *dev = fp->private_data;
+	struct usb_composite_dev *cdev = dev->cdev;
+	struct usb_request *req = 0;
+	int r = count, xfer;
+	int ret;
+
+	DBG(cdev, "acc_write(%d)\n", count);
+
+	if (!dev->online || dev->disconnected)
+		return -ENODEV;
+
+	while (count > 0) {
+		if (!dev->online) {
+			DBG(cdev, "acc_write dev->error\n");
+			r = -EIO;
+			break;
+		}
+
+		/* get an idle tx request to use */
+		req = 0;
+		ret = wait_event_interruptible(dev->write_wq,
+			((req = req_get(dev, &dev->tx_idle)) || !dev->online));
+		if (!req) {
+			r = ret;
+			break;
+		}
+
+		if (count > BULK_BUFFER_SIZE)
+			xfer = BULK_BUFFER_SIZE;
+		else
+			xfer = count;
+		if (copy_from_user(req->buf, buf, xfer)) {
+			r = -EFAULT;
+			break;
+		}
+
+		req->length = xfer;
+		ret = usb_ep_queue(dev->ep_in, req, GFP_KERNEL);
+		if (ret < 0) {
+			DBG(cdev, "acc_write: xfer error %d\n", ret);
+			r = -EIO;
+			break;
+		}
+
+		buf += xfer;
+		count -= xfer;
+
+		/* zero this so we don't try to free it on error exit */
+		req = 0;
+	}
+
+	if (req)
+		req_put(dev, &dev->tx_idle, req);
+
+	DBG(cdev, "acc_write returning %d\n", r);
+	return r;
+}
+
+static long acc_ioctl(struct file *fp, unsigned code, unsigned long value)
+{
+	struct acc_dev *dev = fp->private_data;
+	char *src = NULL;
+	int ret;
+
+	if (dev->function.disabled)
+		return -ENODEV;
+
+	switch (code) {
+	case ACCESSORY_GET_STRING_MANUFACTURER:
+		src = dev->manufacturer;
+		break;
+	case ACCESSORY_GET_STRING_MODEL:
+		src = dev->model;
+		break;
+	case ACCESSORY_GET_STRING_DESCRIPTION:
+		src = dev->description;
+		break;
+	case ACCESSORY_GET_STRING_VERSION:
+		src = dev->version;
+		break;
+	case ACCESSORY_GET_STRING_URI:
+		src = dev->uri;
+		break;
+	case ACCESSORY_GET_STRING_SERIAL:
+		src = dev->serial;
+		break;
+	}
+	if (!src)
+		return -EINVAL;
+
+	ret = strlen(src) + 1;
+	if (copy_to_user((void __user *)value, src, ret))
+		ret = -EFAULT;
+	return ret;
+}
+
+static int acc_open(struct inode *ip, struct file *fp)
+{
+	printk(KERN_INFO "acc_open\n");
+	if (atomic_xchg(&_acc_dev->open_excl, 1))
+		return -EBUSY;
+
+	_acc_dev->disconnected = 0;
+	fp->private_data = _acc_dev;
+	return 0;
+}
+
+static int acc_release(struct inode *ip, struct file *fp)
+{
+	printk(KERN_INFO "acc_release\n");
+
+	WARN_ON(!atomic_xchg(&_acc_dev->open_excl, 0));
+	_acc_dev->disconnected = 0;
+	return 0;
+}
+
+/* file operations for /dev/acc_usb */
+static const struct file_operations acc_fops = {
+	.owner = THIS_MODULE,
+	.read = acc_read,
+	.write = acc_write,
+	.unlocked_ioctl = acc_ioctl,
+	.open = acc_open,
+	.release = acc_release,
+};
+
+static struct miscdevice acc_device = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "usb_accessory",
+	.fops = &acc_fops,
+};
+
+static int
+acc_function_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct acc_dev	*dev = func_to_dev(f);
+	int			id;
+	int			ret;
+
+	dev->cdev = cdev;
+	DBG(cdev, "acc_function_bind dev: %p\n", dev);
+
+	/* allocate interface ID(s) */
+	id = usb_interface_id(c, f);
+	if (id < 0)
+		return id;
+	acc_interface_desc.bInterfaceNumber = id;
+
+	/* allocate endpoints */
+	ret = create_bulk_endpoints(dev, &acc_fullspeed_in_desc,
+			&acc_fullspeed_out_desc);
+	if (ret)
+		return ret;
+
+	/* support high speed hardware */
+	if (gadget_is_dualspeed(c->cdev->gadget)) {
+		acc_highspeed_in_desc.bEndpointAddress =
+			acc_fullspeed_in_desc.bEndpointAddress;
+		acc_highspeed_out_desc.bEndpointAddress =
+			acc_fullspeed_out_desc.bEndpointAddress;
+	}
+
+	DBG(cdev, "%s speed %s: IN/%s, OUT/%s\n",
+			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+			f->name, dev->ep_in->name, dev->ep_out->name);
+	return 0;
+}
+
+static void
+acc_function_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct acc_dev	*dev = func_to_dev(f);
+	struct usb_request *req;
+	int i;
+
+	spin_lock_irq(&dev->lock);
+	while ((req = req_get(dev, &dev->tx_idle)))
+		acc_request_free(req, dev->ep_in);
+	for (i = 0; i < RX_REQ_MAX; i++)
+		acc_request_free(dev->rx_req[i], dev->ep_out);
+	dev->online = 0;
+	spin_unlock_irq(&dev->lock);
+
+	misc_deregister(&acc_device);
+	kfree(_acc_dev);
+	_acc_dev = NULL;
+}
+
+static void acc_work(struct work_struct *data)
+{
+	struct delayed_work *delayed = to_delayed_work(data);
+	struct acc_dev	*dev =
+		container_of(delayed, struct acc_dev, work);
+	android_enable_function(&dev->function, 1);
+}
+
+static int acc_function_setup(struct usb_function *f,
+					const struct usb_ctrlrequest *ctrl)
+{
+	struct acc_dev	*dev = func_to_dev(f);
+	struct usb_composite_dev *cdev = dev->cdev;
+	int	value = -EOPNOTSUPP;
+	u8 b_requestType = ctrl->bRequestType;
+	u8 b_request = ctrl->bRequest;
+	u16	w_index = le16_to_cpu(ctrl->wIndex);
+	u16	w_value = le16_to_cpu(ctrl->wValue);
+	u16	w_length = le16_to_cpu(ctrl->wLength);
+
+/*
+	printk(KERN_INFO "acc_function_setup "
+			"%02x.%02x v%04x i%04x l%u\n",
+			b_requestType, b_request,
+			w_value, w_index, w_length);
+*/
+
+	if (dev->function.disabled) {
+		if (b_requestType == (USB_DIR_OUT | USB_TYPE_VENDOR)) {
+			if (b_request == ACCESSORY_START) {
+				schedule_delayed_work(
+					&dev->work, msecs_to_jiffies(10));
+				value = 0;
+			} else if (b_request == ACCESSORY_SEND_STRING) {
+				dev->string_index = w_index;
+				cdev->gadget->ep0->driver_data = dev;
+				cdev->req->complete = acc_complete_set_string;
+				value = w_length;
+			}
+		} else if (b_requestType == (USB_DIR_IN | USB_TYPE_VENDOR)) {
+			if (b_request == ACCESSORY_GET_PROTOCOL) {
+				*((u16 *)cdev->req->buf) = PROTOCOL_VERSION;
+				value = sizeof(u16);
+
+				/* clear any strings left over from a previous session */
+				memset(dev->manufacturer, 0, sizeof(dev->manufacturer));
+				memset(dev->model, 0, sizeof(dev->model));
+				memset(dev->description, 0, sizeof(dev->description));
+				memset(dev->version, 0, sizeof(dev->version));
+				memset(dev->uri, 0, sizeof(dev->uri));
+				memset(dev->serial, 0, sizeof(dev->serial));
+			}
+		}
+	}
+
+	if (value >= 0) {
+		cdev->req->zero = 0;
+		cdev->req->length = value;
+		value = usb_ep_queue(cdev->gadget->ep0, cdev->req, GFP_ATOMIC);
+		if (value < 0)
+			ERROR(cdev, "%s setup response queue error\n",
+				__func__);
+	}
+
+	if (value == -EOPNOTSUPP)
+		VDBG(cdev,
+			"unknown class-specific control req "
+			"%02x.%02x v%04x i%04x l%u\n",
+			ctrl->bRequestType, ctrl->bRequest,
+			w_value, w_index, w_length);
+	return value;
+}
+
+static int acc_function_set_alt(struct usb_function *f,
+		unsigned intf, unsigned alt)
+{
+	struct acc_dev	*dev = func_to_dev(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+	int ret;
+
+	DBG(cdev, "acc_function_set_alt intf: %d alt: %d\n", intf, alt);
+	ret = usb_ep_enable(dev->ep_in,
+			ep_choose(cdev->gadget,
+				&acc_highspeed_in_desc,
+				&acc_fullspeed_in_desc));
+	if (ret)
+		return ret;
+	ret = usb_ep_enable(dev->ep_out,
+			ep_choose(cdev->gadget,
+				&acc_highspeed_out_desc,
+				&acc_fullspeed_out_desc));
+	if (ret) {
+		usb_ep_disable(dev->ep_in);
+		return ret;
+	}
+	if (!dev->function.disabled)
+		dev->online = 1;
+
+	/* readers may be blocked waiting for us to go online */
+	wake_up(&dev->read_wq);
+	return 0;
+}
+
+static void acc_function_disable(struct usb_function *f)
+{
+	struct acc_dev	*dev = func_to_dev(f);
+	struct usb_composite_dev	*cdev = dev->cdev;
+
+	DBG(cdev, "acc_function_disable\n");
+	acc_set_disconnected(dev);
+	usb_ep_disable(dev->ep_in);
+	usb_ep_disable(dev->ep_out);
+
+	/* readers may be blocked waiting for us to go online */
+	wake_up(&dev->read_wq);
+
+	VDBG(cdev, "%s disabled\n", dev->function.name);
+}
+
+static int acc_bind_config(struct usb_configuration *c)
+{
+	struct acc_dev *dev;
+	int ret;
+
+	printk(KERN_INFO "acc_bind_config\n");
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	/* allocate a string ID for our interface */
+	if (acc_string_defs[INTERFACE_STRING_INDEX].id == 0) {
+		ret = usb_string_id(c->cdev);
+		if (ret < 0)
+			return ret;
+		acc_string_defs[INTERFACE_STRING_INDEX].id = ret;
+		acc_interface_desc.iInterface = ret;
+	}
+
+	spin_lock_init(&dev->lock);
+	init_waitqueue_head(&dev->read_wq);
+	init_waitqueue_head(&dev->write_wq);
+	atomic_set(&dev->open_excl, 0);
+	INIT_LIST_HEAD(&dev->tx_idle);
+	INIT_DELAYED_WORK(&dev->work, acc_work);
+
+	dev->cdev = c->cdev;
+	dev->function.name = "accessory";
+	dev->function.strings = acc_strings,
+	dev->function.descriptors = fs_acc_descs;
+	dev->function.hs_descriptors = hs_acc_descs;
+	dev->function.bind = acc_function_bind;
+	dev->function.unbind = acc_function_unbind;
+	dev->function.setup = acc_function_setup;
+	dev->function.set_alt = acc_function_set_alt;
+	dev->function.disable = acc_function_disable;
+	dev->function.disabled = 1;
+
+	/* _acc_dev must be set before calling usb_gadget_register_driver */
+	_acc_dev = dev;
+
+	ret = misc_register(&acc_device);
+	if (ret)
+		goto err1;
+
+	ret = usb_add_function(c, &dev->function);
+	if (ret)
+		goto err2;
+
+	return 0;
+
+err2:
+	misc_deregister(&acc_device);
+err1:
+	kfree(dev);
+	printk(KERN_ERR "USB accessory gadget driver failed to initialize\n");
+	return ret;
+}
+
+static struct android_usb_function acc_function = {
+	.name = "accessory",
+	.bind_config = acc_bind_config,
+};
+
+static int __init init(void)
+{
+	printk(KERN_INFO "f_accessory init\n");
+	android_register_function(&acc_function);
+	return 0;
+}
+module_init(init);

include/linux/usb/composite.h

@@ -101,6 +101,7 @@ struct usb_function {
 
 	struct usb_configuration	*config;
 	int				hidden;
+	int				disabled;
 
 	/* REVISIT:  bind() functions can be marked __init, which
 	 * makes trouble for section mismatch analysis.  See if

include/linux/usb/f_accessory.h

@@ -0,0 +1,81 @@
+/*
+ * Gadget Function Driver for Android USB accessories
+ *
+ * Copyright (C) 2011 Google, Inc.
+ * Author: Mike Lockwood <lockwood@android.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __LINUX_USB_F_ACCESSORY_H
+#define __LINUX_USB_F_ACCESSORY_H
+
+/* Use Google Vendor ID when in accessory mode */
+#define USB_ACCESSORY_VENDOR_ID 0x18D1
+
+
+/* Product ID to use when in accessory mode */
+#define USB_ACCESSORY_PRODUCT_ID 0x2D00
+
+/* Product ID to use when in accessory mode and adb is enabled */
+#define USB_ACCESSORY_ADB_PRODUCT_ID 0x2D01
+
+/* Indexes for strings sent by the host via ACCESSORY_SEND_STRING */
+#define ACCESSORY_STRING_MANUFACTURER   0
+#define ACCESSORY_STRING_MODEL          1
+#define ACCESSORY_STRING_DESCRIPTION    2
+#define ACCESSORY_STRING_VERSION        3
+#define ACCESSORY_STRING_URI            4
+#define ACCESSORY_STRING_SERIAL         5
+
+/* Control request for retrieving device's protocol version (currently 1)
+ *
+ *	requestType:    USB_DIR_IN | USB_TYPE_VENDOR
+ *	request:        ACCESSORY_GET_PROTOCOL
+ *	value:          0
+ *	index:          0
+ *	data            version number (16 bits little endian)
+ */
+#define ACCESSORY_GET_PROTOCOL  51
+
+/* Control request for host to send a string to the device
+ *
+ *	requestType:    USB_DIR_OUT | USB_TYPE_VENDOR
+ *	request:        ACCESSORY_SEND_STRING
+ *	value:          0
+ *	index:          string ID
+ *	data            zero terminated UTF8 string
+ *
+ *  The device can later retrieve these strings via the
+ *  ACCESSORY_GET_STRING_* ioctls
+ */
+#define ACCESSORY_SEND_STRING   52
+
+/* Control request for starting device in accessory mode.
+ * The host sends this after setting all its strings to the device.
+ *
+ *	requestType:    USB_DIR_OUT | USB_TYPE_VENDOR
+ *	request:        ACCESSORY_START
+ *	value:          0
+ *	index:          0
+ *	data            none
+ */
+#define ACCESSORY_START         53
+
+/* ioctls for retrieving strings set by the host */
+#define ACCESSORY_GET_STRING_MANUFACTURER   _IOW('M', 1, char[256])
+#define ACCESSORY_GET_STRING_MODEL          _IOW('M', 2, char[256])
+#define ACCESSORY_GET_STRING_DESCRIPTION    _IOW('M', 3, char[256])
+#define ACCESSORY_GET_STRING_VERSION        _IOW('M', 4, char[256])
+#define ACCESSORY_GET_STRING_URI            _IOW('M', 5, char[256])
+#define ACCESSORY_GET_STRING_SERIAL         _IOW('M', 6, char[256])
+
+#endif /* __LINUX_USB_F_ACCESSORY_H */