drivers/usb/gadget/udc-core.c - arm/linux-arm64-legacy - Git at Google

 /**
  * udc.c - Core UDC Framework
  *
  * Copyright (C) 2010 Texas Instruments
  * Author: Felipe Balbi <balbi@ti.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2  of
  * the License as published by the Free Software Foundation.
  *
  * 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.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/list.h>
 #include <linux/err.h>
 #include <linux/dma-mapping.h>
 #include <linux/workqueue.h>

 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>

 /**
  * struct usb_udc - describes one usb device controller
  * @driver - the gadget driver pointer. For use by the class code
  * @dev - the child device to the actual controller
  * @gadget - the gadget. For use by the class code
  * @list - for use by the udc class driver
  *
  * This represents the internal data structure which is used by the UDC-class
  * to hold information about udc driver and gadget together.
  */
 struct usb_udc {
 	struct usb_gadget_driver	*driver;
 	struct usb_gadget		*gadget;
 	struct device			dev;
 	struct list_head		list;
 };

 static struct class *udc_class;
 static LIST_HEAD(udc_list);
 static DEFINE_MUTEX(udc_lock);

 /* ------------------------------------------------------------------------- */

 #ifdef	CONFIG_HAS_DMA

 int usb_gadget_map_request(struct usb_gadget *gadget,
 		struct usb_request *req, int is_in)
 {
 	if (req->length == 0)
 		return 0;

 	if (req->num_sgs) {
 		int     mapped;

 		mapped = dma_map_sg(&gadget->dev, req->sg, req->num_sgs,
 				is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 		if (mapped == 0) {
 			dev_err(&gadget->dev, "failed to map SGs\n");
 			return -EFAULT;
 		}

 		req->num_mapped_sgs = mapped;
 	} else {
 		req->dma = dma_map_single(&gadget->dev, req->buf, req->length,
 				is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);

 		if (dma_mapping_error(&gadget->dev, req->dma)) {
 			dev_err(&gadget->dev, "failed to map buffer\n");
 			return -EFAULT;
 		}
 	}

 	return 0;
 }
 EXPORT_SYMBOL_GPL(usb_gadget_map_request);

 void usb_gadget_unmap_request(struct usb_gadget *gadget,
 		struct usb_request *req, int is_in)
 {
 	if (req->length == 0)
 		return;

 	if (req->num_mapped_sgs) {
 		dma_unmap_sg(&gadget->dev, req->sg, req->num_mapped_sgs,
 				is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);

 		req->num_mapped_sgs = 0;
 	} else {
 		dma_unmap_single(&gadget->dev, req->dma, req->length,
 				is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 	}
 }
 EXPORT_SYMBOL_GPL(usb_gadget_unmap_request);

 #endif	/* CONFIG_HAS_DMA */

 /* ------------------------------------------------------------------------- */

 static void usb_gadget_state_work(struct work_struct *work)
 {
 	struct usb_gadget	*gadget = work_to_gadget(work);

 	sysfs_notify(&gadget->dev.kobj, NULL, "state");
 }

 void usb_gadget_set_state(struct usb_gadget *gadget,
 		enum usb_device_state state)
 {
 	gadget->state = state;
 	schedule_work(&gadget->work);
 }
 EXPORT_SYMBOL_GPL(usb_gadget_set_state);

 /* ------------------------------------------------------------------------- */

 /**
  * usb_gadget_udc_start - tells usb device controller to start up
  * @gadget: The gadget we want to get started
  * @driver: The driver we want to bind to @gadget
  *
  * This call is issued by the UDC Class driver when it's about
  * to register a gadget driver to the device controller, before
  * calling gadget driver's bind() method.
  *
  * It allows the controller to be powered off until strictly
  * necessary to have it powered on.
  *
  * Returns zero on success, else negative errno.
  */
 static inline int usb_gadget_udc_start(struct usb_gadget *gadget,
 		struct usb_gadget_driver *driver)
 {
 	return gadget->ops->udc_start(gadget, driver);
 }

 /**
  * usb_gadget_udc_stop - tells usb device controller we don't need it anymore
  * @gadget: The device we want to stop activity
  * @driver: The driver to unbind from @gadget
  *
  * This call is issued by the UDC Class driver after calling
  * gadget driver's unbind() method.
  *
  * The details are implementation specific, but it can go as
  * far as powering off UDC completely and disable its data
  * line pullups.
  */
 static inline void usb_gadget_udc_stop(struct usb_gadget *gadget,
 		struct usb_gadget_driver *driver)
 {
 	gadget->ops->udc_stop(gadget, driver);
 }

 /**
  * usb_udc_release - release the usb_udc struct
  * @dev: the dev member within usb_udc
  *
  * This is called by driver's core in order to free memory once the last
  * reference is released.
  */
 static void usb_udc_release(struct device *dev)
 {
 	struct usb_udc *udc;

 	udc = container_of(dev, struct usb_udc, dev);
 	dev_dbg(dev, "releasing '%s'\n", dev_name(dev));
 	kfree(udc);
 }

 static const struct attribute_group *usb_udc_attr_groups[];

 static void usb_udc_nop_release(struct device *dev)
 {
 	dev_vdbg(dev, "%s\n", __func__);
 }

 /**
  * usb_add_gadget_udc_release - adds a new gadget to the udc class driver list
  * @parent: the parent device to this udc. Usually the controller driver's
  * device.
  * @gadget: the gadget to be added to the list.
  * @release: a gadget release function.
  *
  * Returns zero on success, negative errno otherwise.
  */
 int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 		void (*release)(struct device *dev))
 {
 	struct usb_udc		*udc;
 	int			ret = -ENOMEM;

 	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
 	if (!udc)
 		goto err1;

 	dev_set_name(&gadget->dev, "gadget");
 	INIT_WORK(&gadget->work, usb_gadget_state_work);
 	gadget->dev.parent = parent;

 #ifdef	CONFIG_HAS_DMA
 	dma_set_coherent_mask(&gadget->dev, parent->coherent_dma_mask);
 	gadget->dev.dma_parms = parent->dma_parms;
 	gadget->dev.dma_mask = parent->dma_mask;
 #endif

 	if (release)
 		gadget->dev.release = release;
 	else
 		gadget->dev.release = usb_udc_nop_release;

 	ret = device_register(&gadget->dev);
 	if (ret)
 		goto err2;

 	device_initialize(&udc->dev);
 	udc->dev.release = usb_udc_release;
 	udc->dev.class = udc_class;
 	udc->dev.groups = usb_udc_attr_groups;
 	udc->dev.parent = parent;
 	ret = dev_set_name(&udc->dev, "%s", kobject_name(&parent->kobj));
 	if (ret)
 		goto err3;

 	udc->gadget = gadget;

 	mutex_lock(&udc_lock);
 	list_add_tail(&udc->list, &udc_list);

 	ret = device_add(&udc->dev);
 	if (ret)
 		goto err4;

 	usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);

 	mutex_unlock(&udc_lock);

 	return 0;

 err4:
 	list_del(&udc->list);
 	mutex_unlock(&udc_lock);

 err3:
 	put_device(&udc->dev);

 err2:
 	put_device(&gadget->dev);
 	kfree(udc);

 err1:
 	return ret;
 }
 EXPORT_SYMBOL_GPL(usb_add_gadget_udc_release);

 /**
  * usb_add_gadget_udc - adds a new gadget to the udc class driver list
  * @parent: the parent device to this udc. Usually the controller
  * driver's device.
  * @gadget: the gadget to be added to the list
  *
  * Returns zero on success, negative errno otherwise.
  */
 int usb_add_gadget_udc(struct device *parent, struct usb_gadget *gadget)
 {
 	return usb_add_gadget_udc_release(parent, gadget, NULL);
 }
 EXPORT_SYMBOL_GPL(usb_add_gadget_udc);

 static void usb_gadget_remove_driver(struct usb_udc *udc)
 {
 	dev_dbg(&udc->dev, "unregistering UDC driver [%s]\n",
 			udc->gadget->name);

 	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);

 	usb_gadget_disconnect(udc->gadget);
 	udc->driver->disconnect(udc->gadget);
 	udc->driver->unbind(udc->gadget);
 	usb_gadget_udc_stop(udc->gadget, NULL);

 	udc->driver = NULL;
 	udc->dev.driver = NULL;
 	udc->gadget->dev.driver = NULL;
 }

 /**
  * usb_del_gadget_udc - deletes @udc from udc_list
  * @gadget: the gadget to be removed.
  *
  * This, will call usb_gadget_unregister_driver() if
  * the @udc is still busy.
  */
 void usb_del_gadget_udc(struct usb_gadget *gadget)
 {
 	struct usb_udc		*udc = NULL;

 	mutex_lock(&udc_lock);
 	list_for_each_entry(udc, &udc_list, list)
 		if (udc->gadget == gadget)
 			goto found;

 	dev_err(gadget->dev.parent, "gadget not registered.\n");
 	mutex_unlock(&udc_lock);

 	return;

 found:
 	dev_vdbg(gadget->dev.parent, "unregistering gadget\n");

 	list_del(&udc->list);
 	mutex_unlock(&udc_lock);

 	if (udc->driver)
 		usb_gadget_remove_driver(udc);

 	kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
 	flush_work(&gadget->work);
 	device_unregister(&udc->dev);
 	device_unregister(&gadget->dev);
 }
 EXPORT_SYMBOL_GPL(usb_del_gadget_udc);

 /* ------------------------------------------------------------------------- */

 static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *driver)
 {
 	int ret;

 	dev_dbg(&udc->dev, "registering UDC driver [%s]\n",
 			driver->function);

 	udc->driver = driver;
 	udc->dev.driver = &driver->driver;
 	udc->gadget->dev.driver = &driver->driver;

 	ret = driver->bind(udc->gadget, driver);
 	if (ret)
 		goto err1;
 	ret = usb_gadget_udc_start(udc->gadget, driver);
 	if (ret) {
 		driver->unbind(udc->gadget);
 		goto err1;
 	}
 	usb_gadget_connect(udc->gadget);

 	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 	return 0;
 err1:
 	if (ret != -EISNAM)
 		dev_err(&udc->dev, "failed to start %s: %d\n",
 			udc->driver->function, ret);
 	udc->driver = NULL;
 	udc->dev.driver = NULL;
 	udc->gadget->dev.driver = NULL;
 	return ret;
 }

 int udc_attach_driver(const char *name, struct usb_gadget_driver *driver)
 {
 	struct usb_udc *udc = NULL;
 	int ret = -ENODEV;

 	mutex_lock(&udc_lock);
 	list_for_each_entry(udc, &udc_list, list) {
 		ret = strcmp(name, dev_name(&udc->dev));
 		if (!ret)
 			break;
 	}
 	if (ret) {
 		ret = -ENODEV;
 		goto out;
 	}
 	if (udc->driver) {
 		ret = -EBUSY;
 		goto out;
 	}
 	ret = udc_bind_to_driver(udc, driver);
 out:
 	mutex_unlock(&udc_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(udc_attach_driver);

 int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
 {
 	struct usb_udc		*udc = NULL;
 	int			ret;

 	if (!driver || !driver->bind || !driver->setup)
 		return -EINVAL;

 	mutex_lock(&udc_lock);
 	list_for_each_entry(udc, &udc_list, list) {
 		/* For now we take the first one */
 		if (!udc->driver)
 			goto found;
 	}

 	pr_debug("couldn't find an available UDC\n");
 	mutex_unlock(&udc_lock);
 	return -ENODEV;
 found:
 	ret = udc_bind_to_driver(udc, driver);
 	mutex_unlock(&udc_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(usb_gadget_probe_driver);

 int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
 {
 	struct usb_udc		*udc = NULL;
 	int			ret = -ENODEV;

 	if (!driver || !driver->unbind)
 		return -EINVAL;

 	mutex_lock(&udc_lock);
 	list_for_each_entry(udc, &udc_list, list)
 		if (udc->driver == driver) {
 			usb_gadget_remove_driver(udc);
 			usb_gadget_set_state(udc->gadget,
 					USB_STATE_NOTATTACHED);
 			ret = 0;
 			break;
 		}

 	mutex_unlock(&udc_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(usb_gadget_unregister_driver);

 /* ------------------------------------------------------------------------- */

 static ssize_t usb_udc_srp_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t n)
 {
 	struct usb_udc		*udc = container_of(dev, struct usb_udc, dev);

 	if (sysfs_streq(buf, "1"))
 		usb_gadget_wakeup(udc->gadget);

 	return n;
 }
 static DEVICE_ATTR(srp, S_IWUSR, NULL, usb_udc_srp_store);

 static ssize_t usb_udc_softconn_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t n)
 {
 	struct usb_udc		*udc = container_of(dev, struct usb_udc, dev);

 	if (sysfs_streq(buf, "connect")) {
 		usb_gadget_udc_start(udc->gadget, udc->driver);
 		usb_gadget_connect(udc->gadget);
 	} else if (sysfs_streq(buf, "disconnect")) {
 		usb_gadget_disconnect(udc->gadget);
 		usb_gadget_udc_stop(udc->gadget, udc->driver);
 	} else {
 		dev_err(dev, "unsupported command '%s'\n", buf);
 		return -EINVAL;
 	}

 	return n;
 }
 static DEVICE_ATTR(soft_connect, S_IWUSR, NULL, usb_udc_softconn_store);

 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
 	struct usb_udc		*udc = container_of(dev, struct usb_udc, dev);
 	struct usb_gadget	*gadget = udc->gadget;

 	return sprintf(buf, "%s\n", usb_state_string(gadget->state));
 }
 static DEVICE_ATTR_RO(state);

 #define USB_UDC_SPEED_ATTR(name, param)					\
 ssize_t name##_show(struct device *dev,					\
 		struct device_attribute *attr, char *buf)		\
 {									\
 	struct usb_udc *udc = container_of(dev, struct usb_udc, dev);	\
 	return snprintf(buf, PAGE_SIZE, "%s\n",				\
 			usb_speed_string(udc->gadget->param));		\
 }									\
 static DEVICE_ATTR_RO(name)

 static USB_UDC_SPEED_ATTR(current_speed, speed);
 static USB_UDC_SPEED_ATTR(maximum_speed, max_speed);

 #define USB_UDC_ATTR(name)					\
 ssize_t name##_show(struct device *dev,				\
 		struct device_attribute *attr, char *buf)	\
 {								\
 	struct usb_udc		*udc = container_of(dev, struct usb_udc, dev); \
 	struct usb_gadget	*gadget = udc->gadget;		\
 								\
 	return snprintf(buf, PAGE_SIZE, "%d\n", gadget->name);	\
 }								\
 static DEVICE_ATTR_RO(name)

 static USB_UDC_ATTR(is_otg);
 static USB_UDC_ATTR(is_a_peripheral);
 static USB_UDC_ATTR(b_hnp_enable);
 static USB_UDC_ATTR(a_hnp_support);
 static USB_UDC_ATTR(a_alt_hnp_support);

 static struct attribute *usb_udc_attrs[] = {
 	&dev_attr_srp.attr,
 	&dev_attr_soft_connect.attr,
 	&dev_attr_state.attr,
 	&dev_attr_current_speed.attr,
 	&dev_attr_maximum_speed.attr,

 	&dev_attr_is_otg.attr,
 	&dev_attr_is_a_peripheral.attr,
 	&dev_attr_b_hnp_enable.attr,
 	&dev_attr_a_hnp_support.attr,
 	&dev_attr_a_alt_hnp_support.attr,
 	NULL,
 };

 static const struct attribute_group usb_udc_attr_group = {
 	.attrs = usb_udc_attrs,
 };

 static const struct attribute_group *usb_udc_attr_groups[] = {
 	&usb_udc_attr_group,
 	NULL,
 };

 static int usb_udc_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
 	struct usb_udc		*udc = container_of(dev, struct usb_udc, dev);
 	int			ret;

 	ret = add_uevent_var(env, "USB_UDC_NAME=%s", udc->gadget->name);
 	if (ret) {
 		dev_err(dev, "failed to add uevent USB_UDC_NAME\n");
 		return ret;
 	}

 	if (udc->driver) {
 		ret = add_uevent_var(env, "USB_UDC_DRIVER=%s",
 				udc->driver->function);
 		if (ret) {
 			dev_err(dev, "failed to add uevent USB_UDC_DRIVER\n");
 			return ret;
 		}
 	}

 	return 0;
 }

 static int __init usb_udc_init(void)
 {
 	udc_class = class_create(THIS_MODULE, "udc");
 	if (IS_ERR(udc_class)) {
 		pr_err("failed to create udc class --> %ld\n",
 				PTR_ERR(udc_class));
 		return PTR_ERR(udc_class);
 	}

 	udc_class->dev_uevent = usb_udc_uevent;
 	return 0;
 }
 subsys_initcall(usb_udc_init);

 static void __exit usb_udc_exit(void)
 {
 	class_destroy(udc_class);
 }
 module_exit(usb_udc_exit);

 MODULE_DESCRIPTION("UDC Framework");
 MODULE_AUTHOR("Felipe Balbi <balbi@ti.com>");
 MODULE_LICENSE("GPL v2");
	/**
	* udc.c - Core UDC Framework
	*
	* Copyright (C) 2010 Texas Instruments
	* Author: Felipe Balbi <balbi@ti.com>
	*
	* This program is free software: you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 of
	* the License as published by the Free Software Foundation.
	*
	* 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.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/list.h>
	#include <linux/err.h>
	#include <linux/dma-mapping.h>
	#include <linux/workqueue.h>

	#include <linux/usb/ch9.h>
	#include <linux/usb/gadget.h>

	/**
	* struct usb_udc - describes one usb device controller
	* @driver - the gadget driver pointer. For use by the class code
	* @dev - the child device to the actual controller
	* @gadget - the gadget. For use by the class code
	* @list - for use by the udc class driver
	*
	* This represents the internal data structure which is used by the UDC-class
	* to hold information about udc driver and gadget together.
	*/
	struct usb_udc {
	struct usb_gadget_driver *driver;
	struct usb_gadget *gadget;
	struct device dev;
	struct list_head list;
	};

	static struct class *udc_class;
	static LIST_HEAD(udc_list);
	static DEFINE_MUTEX(udc_lock);

	/* ------------------------------------------------------------------------- */

	#ifdef CONFIG_HAS_DMA

	int usb_gadget_map_request(struct usb_gadget *gadget,
	struct usb_request *req, int is_in)
	{
	if (req->length == 0)
	return 0;

	if (req->num_sgs) {
	int mapped;

	mapped = dma_map_sg(&gadget->dev, req->sg, req->num_sgs,
	is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
	if (mapped == 0) {
	dev_err(&gadget->dev, "failed to map SGs\n");
	return -EFAULT;
	}

	req->num_mapped_sgs = mapped;
	} else {
	req->dma = dma_map_single(&gadget->dev, req->buf, req->length,
	is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);

	if (dma_mapping_error(&gadget->dev, req->dma)) {
	dev_err(&gadget->dev, "failed to map buffer\n");
	return -EFAULT;
	}
	}

	return 0;
	}
	EXPORT_SYMBOL_GPL(usb_gadget_map_request);

	void usb_gadget_unmap_request(struct usb_gadget *gadget,
	struct usb_request *req, int is_in)
	{
	if (req->length == 0)
	return;

	if (req->num_mapped_sgs) {
	dma_unmap_sg(&gadget->dev, req->sg, req->num_mapped_sgs,
	is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);

	req->num_mapped_sgs = 0;
	} else {
	dma_unmap_single(&gadget->dev, req->dma, req->length,
	is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
	}
	}
	EXPORT_SYMBOL_GPL(usb_gadget_unmap_request);

	#endif /* CONFIG_HAS_DMA */

	/* ------------------------------------------------------------------------- */

	static void usb_gadget_state_work(struct work_struct *work)
	{
	struct usb_gadget *gadget = work_to_gadget(work);

	sysfs_notify(&gadget->dev.kobj, NULL, "state");
	}

	void usb_gadget_set_state(struct usb_gadget *gadget,
	enum usb_device_state state)
	{
	gadget->state = state;
	schedule_work(&gadget->work);
	}
	EXPORT_SYMBOL_GPL(usb_gadget_set_state);

	/* ------------------------------------------------------------------------- */

	/**
	* usb_gadget_udc_start - tells usb device controller to start up
	* @gadget: The gadget we want to get started
	* @driver: The driver we want to bind to @gadget
	*
	* This call is issued by the UDC Class driver when it's about
	* to register a gadget driver to the device controller, before
	* calling gadget driver's bind() method.
	*
	* It allows the controller to be powered off until strictly
	* necessary to have it powered on.
	*
	* Returns zero on success, else negative errno.
	*/
	static inline int usb_gadget_udc_start(struct usb_gadget *gadget,
	struct usb_gadget_driver *driver)
	{
	return gadget->ops->udc_start(gadget, driver);
	}

	/**
	* usb_gadget_udc_stop - tells usb device controller we don't need it anymore
	* @gadget: The device we want to stop activity
	* @driver: The driver to unbind from @gadget
	*
	* This call is issued by the UDC Class driver after calling
	* gadget driver's unbind() method.
	*
	* The details are implementation specific, but it can go as
	* far as powering off UDC completely and disable its data
	* line pullups.
	*/
	static inline void usb_gadget_udc_stop(struct usb_gadget *gadget,
	struct usb_gadget_driver *driver)
	{
	gadget->ops->udc_stop(gadget, driver);
	}

	/**
	* usb_udc_release - release the usb_udc struct
	* @dev: the dev member within usb_udc
	*
	* This is called by driver's core in order to free memory once the last
	* reference is released.
	*/
	static void usb_udc_release(struct device *dev)
	{
	struct usb_udc *udc;

	udc = container_of(dev, struct usb_udc, dev);
	dev_dbg(dev, "releasing '%s'\n", dev_name(dev));
	kfree(udc);
	}

	static const struct attribute_group *usb_udc_attr_groups[];

	static void usb_udc_nop_release(struct device *dev)
	{
	dev_vdbg(dev, "%s\n", __func__);
	}

	/**
	* usb_add_gadget_udc_release - adds a new gadget to the udc class driver list
	* @parent: the parent device to this udc. Usually the controller driver's
	* device.
	* @gadget: the gadget to be added to the list.
	* @release: a gadget release function.
	*
	* Returns zero on success, negative errno otherwise.
	*/
	int usb_add_gadget_udc_release(struct device parent, struct usb_gadget gadget,
	void (release)(struct device dev))
	{
	struct usb_udc *udc;
	int ret = -ENOMEM;

	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
	if (!udc)
	goto err1;

	dev_set_name(&gadget->dev, "gadget");
	INIT_WORK(&gadget->work, usb_gadget_state_work);
	gadget->dev.parent = parent;

	#ifdef CONFIG_HAS_DMA
	dma_set_coherent_mask(&gadget->dev, parent->coherent_dma_mask);
	gadget->dev.dma_parms = parent->dma_parms;
	gadget->dev.dma_mask = parent->dma_mask;
	#endif

	if (release)
	gadget->dev.release = release;
	else
	gadget->dev.release = usb_udc_nop_release;

	ret = device_register(&gadget->dev);
	if (ret)
	goto err2;

	device_initialize(&udc->dev);
	udc->dev.release = usb_udc_release;
	udc->dev.class = udc_class;
	udc->dev.groups = usb_udc_attr_groups;
	udc->dev.parent = parent;
	ret = dev_set_name(&udc->dev, "%s", kobject_name(&parent->kobj));
	if (ret)
	goto err3;

	udc->gadget = gadget;

	mutex_lock(&udc_lock);
	list_add_tail(&udc->list, &udc_list);

	ret = device_add(&udc->dev);
	if (ret)
	goto err4;

	usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);

	mutex_unlock(&udc_lock);

	return 0;

	err4:
	list_del(&udc->list);
	mutex_unlock(&udc_lock);

	err3:
	put_device(&udc->dev);

	err2:
	put_device(&gadget->dev);
	kfree(udc);

	err1:
	return ret;
	}
	EXPORT_SYMBOL_GPL(usb_add_gadget_udc_release);

	/**
	* usb_add_gadget_udc - adds a new gadget to the udc class driver list
	* @parent: the parent device to this udc. Usually the controller
	* driver's device.
	* @gadget: the gadget to be added to the list
	*
	* Returns zero on success, negative errno otherwise.
	*/
	int usb_add_gadget_udc(struct device parent, struct usb_gadget gadget)
	{
	return usb_add_gadget_udc_release(parent, gadget, NULL);
	}
	EXPORT_SYMBOL_GPL(usb_add_gadget_udc);

	static void usb_gadget_remove_driver(struct usb_udc *udc)
	{
	dev_dbg(&udc->dev, "unregistering UDC driver [%s]\n",
	udc->gadget->name);

	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);

	usb_gadget_disconnect(udc->gadget);
	udc->driver->disconnect(udc->gadget);
	udc->driver->unbind(udc->gadget);
	usb_gadget_udc_stop(udc->gadget, NULL);

	udc->driver = NULL;
	udc->dev.driver = NULL;
	udc->gadget->dev.driver = NULL;
	}

	/**
	* usb_del_gadget_udc - deletes @udc from udc_list
	* @gadget: the gadget to be removed.
	*
	* This, will call usb_gadget_unregister_driver() if
	* the @udc is still busy.
	*/
	void usb_del_gadget_udc(struct usb_gadget *gadget)
	{
	struct usb_udc *udc = NULL;

	mutex_lock(&udc_lock);
	list_for_each_entry(udc, &udc_list, list)
	if (udc->gadget == gadget)
	goto found;

	dev_err(gadget->dev.parent, "gadget not registered.\n");
	mutex_unlock(&udc_lock);

	return;

	found:
	dev_vdbg(gadget->dev.parent, "unregistering gadget\n");

	list_del(&udc->list);
	mutex_unlock(&udc_lock);

	if (udc->driver)
	usb_gadget_remove_driver(udc);

	kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
	flush_work(&gadget->work);
	device_unregister(&udc->dev);
	device_unregister(&gadget->dev);
	}
	EXPORT_SYMBOL_GPL(usb_del_gadget_udc);

	/* ------------------------------------------------------------------------- */

	static int udc_bind_to_driver(struct usb_udc udc, struct usb_gadget_driver driver)
	{
	int ret;

	dev_dbg(&udc->dev, "registering UDC driver [%s]\n",
	driver->function);

	udc->driver = driver;
	udc->dev.driver = &driver->driver;
	udc->gadget->dev.driver = &driver->driver;

	ret = driver->bind(udc->gadget, driver);
	if (ret)
	goto err1;
	ret = usb_gadget_udc_start(udc->gadget, driver);
	if (ret) {
	driver->unbind(udc->gadget);
	goto err1;
	}
	usb_gadget_connect(udc->gadget);

	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
	return 0;
	err1:
	if (ret != -EISNAM)
	dev_err(&udc->dev, "failed to start %s: %d\n",
	udc->driver->function, ret);
	udc->driver = NULL;
	udc->dev.driver = NULL;
	udc->gadget->dev.driver = NULL;
	return ret;
	}

	int udc_attach_driver(const char name, struct usb_gadget_driver driver)
	{
	struct usb_udc *udc = NULL;
	int ret = -ENODEV;

	mutex_lock(&udc_lock);
	list_for_each_entry(udc, &udc_list, list) {
	ret = strcmp(name, dev_name(&udc->dev));
	if (!ret)
	break;
	}
	if (ret) {
	ret = -ENODEV;
	goto out;
	}
	if (udc->driver) {
	ret = -EBUSY;
	goto out;
	}
	ret = udc_bind_to_driver(udc, driver);
	out:
	mutex_unlock(&udc_lock);
	return ret;
	}
	EXPORT_SYMBOL_GPL(udc_attach_driver);

	int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
	{
	struct usb_udc *udc = NULL;
	int ret;

	if (!driver \|\| !driver->bind \|\| !driver->setup)
	return -EINVAL;

	mutex_lock(&udc_lock);
	list_for_each_entry(udc, &udc_list, list) {
	/* For now we take the first one */
	if (!udc->driver)
	goto found;
	}

	pr_debug("couldn't find an available UDC\n");
	mutex_unlock(&udc_lock);
	return -ENODEV;
	found:
	ret = udc_bind_to_driver(udc, driver);
	mutex_unlock(&udc_lock);
	return ret;
	}
	EXPORT_SYMBOL_GPL(usb_gadget_probe_driver);

	int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
	{
	struct usb_udc *udc = NULL;
	int ret = -ENODEV;

	if (!driver \|\| !driver->unbind)
	return -EINVAL;

	mutex_lock(&udc_lock);
	list_for_each_entry(udc, &udc_list, list)
	if (udc->driver == driver) {
	usb_gadget_remove_driver(udc);
	usb_gadget_set_state(udc->gadget,
	USB_STATE_NOTATTACHED);
	ret = 0;
	break;
	}

	mutex_unlock(&udc_lock);
	return ret;
	}
	EXPORT_SYMBOL_GPL(usb_gadget_unregister_driver);

	/* ------------------------------------------------------------------------- */

	static ssize_t usb_udc_srp_store(struct device *dev,
	struct device_attribute attr, const char buf, size_t n)
	{
	struct usb_udc *udc = container_of(dev, struct usb_udc, dev);

	if (sysfs_streq(buf, "1"))
	usb_gadget_wakeup(udc->gadget);

	return n;
	}
	static DEVICE_ATTR(srp, S_IWUSR, NULL, usb_udc_srp_store);

	static ssize_t usb_udc_softconn_store(struct device *dev,
	struct device_attribute attr, const char buf, size_t n)
	{
	struct usb_udc *udc = container_of(dev, struct usb_udc, dev);

	if (sysfs_streq(buf, "connect")) {
	usb_gadget_udc_start(udc->gadget, udc->driver);
	usb_gadget_connect(udc->gadget);
	} else if (sysfs_streq(buf, "disconnect")) {
	usb_gadget_disconnect(udc->gadget);
	usb_gadget_udc_stop(udc->gadget, udc->driver);
	} else {
	dev_err(dev, "unsupported command '%s'\n", buf);
	return -EINVAL;
	}

	return n;
	}
	static DEVICE_ATTR(soft_connect, S_IWUSR, NULL, usb_udc_softconn_store);

	static ssize_t state_show(struct device dev, struct device_attribute attr,
	char *buf)
	{
	struct usb_udc *udc = container_of(dev, struct usb_udc, dev);
	struct usb_gadget *gadget = udc->gadget;

	return sprintf(buf, "%s\n", usb_state_string(gadget->state));
	}
	static DEVICE_ATTR_RO(state);

	#define USB_UDC_SPEED_ATTR(name, param) \
	ssize_t name##_show(struct device *dev, \
	struct device_attribute attr, char buf) \
	{ \
	struct usb_udc *udc = container_of(dev, struct usb_udc, dev); \
	return snprintf(buf, PAGE_SIZE, "%s\n", \
	usb_speed_string(udc->gadget->param)); \
	} \
	static DEVICE_ATTR_RO(name)

	static USB_UDC_SPEED_ATTR(current_speed, speed);
	static USB_UDC_SPEED_ATTR(maximum_speed, max_speed);

	#define USB_UDC_ATTR(name) \
	ssize_t name##_show(struct device *dev, \
	struct device_attribute attr, char buf) \
	{ \
	struct usb_udc *udc = container_of(dev, struct usb_udc, dev); \
	struct usb_gadget *gadget = udc->gadget; \
	\
	return snprintf(buf, PAGE_SIZE, "%d\n", gadget->name); \
	} \
	static DEVICE_ATTR_RO(name)

	static USB_UDC_ATTR(is_otg);
	static USB_UDC_ATTR(is_a_peripheral);
	static USB_UDC_ATTR(b_hnp_enable);
	static USB_UDC_ATTR(a_hnp_support);
	static USB_UDC_ATTR(a_alt_hnp_support);

	static struct attribute *usb_udc_attrs[] = {
	&dev_attr_srp.attr,
	&dev_attr_soft_connect.attr,
	&dev_attr_state.attr,
	&dev_attr_current_speed.attr,
	&dev_attr_maximum_speed.attr,

	&dev_attr_is_otg.attr,
	&dev_attr_is_a_peripheral.attr,
	&dev_attr_b_hnp_enable.attr,
	&dev_attr_a_hnp_support.attr,
	&dev_attr_a_alt_hnp_support.attr,
	NULL,
	};

	static const struct attribute_group usb_udc_attr_group = {
	.attrs = usb_udc_attrs,
	};

	static const struct attribute_group *usb_udc_attr_groups[] = {
	&usb_udc_attr_group,
	NULL,
	};

	static int usb_udc_uevent(struct device dev, struct kobj_uevent_env env)
	{
	struct usb_udc *udc = container_of(dev, struct usb_udc, dev);
	int ret;

	ret = add_uevent_var(env, "USB_UDC_NAME=%s", udc->gadget->name);
	if (ret) {
	dev_err(dev, "failed to add uevent USB_UDC_NAME\n");
	return ret;
	}

	if (udc->driver) {
	ret = add_uevent_var(env, "USB_UDC_DRIVER=%s",
	udc->driver->function);
	if (ret) {
	dev_err(dev, "failed to add uevent USB_UDC_DRIVER\n");
	return ret;
	}
	}

	return 0;
	}

	static int __init usb_udc_init(void)
	{
	udc_class = class_create(THIS_MODULE, "udc");
	if (IS_ERR(udc_class)) {
	pr_err("failed to create udc class --> %ld\n",
	PTR_ERR(udc_class));
	return PTR_ERR(udc_class);
	}

	udc_class->dev_uevent = usb_udc_uevent;
	return 0;
	}
	subsys_initcall(usb_udc_init);

	static void __exit usb_udc_exit(void)
	{
	class_destroy(udc_class);
	}
	module_exit(usb_udc_exit);

	MODULE_DESCRIPTION("UDC Framework");
	MODULE_AUTHOR("Felipe Balbi <balbi@ti.com>");
	MODULE_LICENSE("GPL v2");