usb: gadget: introduce UDC Class

this class will be used to abstract away several of the duplicated
operations scattered among the USB gadget controller drivers.

Later, we can add an atomic notifier to tell interested drivers about
what's happening with the controller. Notifications such as suspend,
resume, enumerated, etc. will be useful, at a minimum, for implementing
usb charger detection.

As part of the converting process usb_gadget_probe_driver() is no longer
part of each udc but pushed into the ->stap() callback. The same for his
couterpart.

The core is currently set explicit to 'n'. It will be changed to 'y' once
all users are converted since it provides functions which clash with
other drivers.

Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 425 insertions, 0 deletions

diff --git a/drivers/usb/gadget/udc-core.c b/drivers/usb/gadget/udc-core.c
new file mode 100644
index 000000000000..83e9e5f99b4a
--- /dev/null
+++ b/drivers/usb/gadget/udc-core.c
@@ -0,0 +1,418 @@
+/**
+ * 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/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 struct device_type udc_device_type;
+static LIST_HEAD(udc_list);
+static DEFINE_MUTEX(udc_lock);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * usb_gadget_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
+ * @bind: The bind function for @driver
+ *
+ * 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_start(struct usb_gadget *gadget,
+		struct usb_gadget_driver *driver,
+		int (*bind)(struct usb_gadget *))
+{
+	return gadget->ops->start(driver, bind);
+}
+
+/**
+ * usb_gadget_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_stop(struct usb_gadget *gadget,
+		struct usb_gadget_driver *driver)
+{
+	gadget->ops->stop(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);
+}
+
+/**
+ * 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)
+{
+	struct usb_udc		*udc;
+	int			ret = -ENOMEM;
+
+	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
+	if (!udc)
+		goto err1;
+
+	device_initialize(&udc->dev);
+	udc->dev.release = usb_udc_release;
+	udc->dev.class = udc_class;
+	udc->dev.parent = parent;
+	ret = dev_set_name(&udc->dev, "%s", kobject_name(&parent->kobj));
+	if (ret)
+		goto err2;
+
+	udc->gadget = gadget;
+
+	mutex_lock(&udc_lock);
+	list_add_tail(&udc->list, &udc_list);
+
+	ret = device_add(&udc->dev);
+	if (ret)
+		goto err3;
+
+	mutex_unlock(&udc_lock);
+
+	return 0;
+err3:
+	list_del(&udc->list);
+	mutex_unlock(&udc_lock);
+
+err2:
+	put_device(&udc->dev);
+
+err1:
+	return ret;
+}
+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_stop(udc->gadget, udc->driver);
+
+	udc->driver = NULL;
+	udc->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);
+	device_unregister(&udc->dev);
+}
+EXPORT_SYMBOL_GPL(usb_del_gadget_udc);
+
+/* ------------------------------------------------------------------------- */
+
+int usb_gadget_probe_driver(struct usb_gadget_driver *driver,
+		int (*bind)(struct usb_gadget *))
+{
+	struct usb_udc		*udc = NULL;
+	int			ret;
+
+	if (!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:
+	dev_dbg(&udc->dev, "registering UDC driver [%s]\n",
+			driver->function);
+
+	udc->driver = driver;
+	udc->dev.driver = &driver->driver;
+
+	ret = usb_gadget_start(udc->gadget, driver, bind);
+	if (ret)
+		goto err1;
+
+	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
+	mutex_unlock(&udc_lock);
+	return 0;
+
+err1:
+	dev_err(&udc->dev, "failed to start %s: %d\n",
+			udc->driver->function, ret);
+	udc->driver = NULL;
+	udc->dev.driver = NULL;
+	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);
+			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 = dev_get_drvdata(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 = dev_get_drvdata(dev);
+
+	if (sysfs_streq(buf, "connect")) {
+		usb_gadget_connect(udc->gadget);
+	} else if (sysfs_streq(buf, "disconnect")) {
+		usb_gadget_disconnect(udc->gadget);
+	} 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 usb_udc_speed_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct usb_udc		*udc = dev_get_drvdata(dev);
+	struct usb_gadget	*gadget = udc->gadget;
+
+	switch (gadget->speed) {
+	case USB_SPEED_LOW:
+		return snprintf(buf, PAGE_SIZE, "low-speed\n");
+	case USB_SPEED_FULL:
+		return snprintf(buf, PAGE_SIZE, "full-speed\n");
+	case USB_SPEED_HIGH:
+		return snprintf(buf, PAGE_SIZE, "high-speed\n");
+	case USB_SPEED_WIRELESS:
+		return snprintf(buf, PAGE_SIZE, "wireless\n");
+	case USB_SPEED_SUPER:
+		return snprintf(buf, PAGE_SIZE, "super-speed\n");
+	case USB_SPEED_UNKNOWN:	/* FALLTHROUGH */
+	default:
+		return snprintf(buf, PAGE_SIZE, "UNKNOWN\n");
+	}
+}
+static DEVICE_ATTR(speed, S_IRUSR, usb_udc_speed_show, NULL);
+
+#define USB_UDC_ATTR(name)					\
+ssize_t usb_udc_##name##_show(struct device *dev,		\
+		struct device_attribute *attr, char *buf)	\
+{								\
+	struct usb_udc		*udc = dev_get_drvdata(dev);	\
+	struct usb_gadget	*gadget = udc->gadget;		\
+								\
+	return snprintf(buf, PAGE_SIZE, "%d\n", gadget->name);	\
+}								\
+static DEVICE_ATTR(name, S_IRUSR, usb_udc_##name##_show, NULL)
+
+static USB_UDC_ATTR(is_dualspeed);
+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_speed.attr,
+
+	&dev_attr_is_dualspeed.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;
+	udc_device_type.groups = usb_udc_attr_groups;
+
+	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");
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 55d1a88ff11f..18979cfb6d66 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -418,6 +418,7 @@ static inline void usb_ep_fifo_flush(struct usb_ep *ep)
 /*-------------------------------------------------------------------------*/
 
 struct usb_gadget;
+struct usb_gadget_driver;
 
 /* the rest of the api to the controller hardware: device operations,
  * which don't involve endpoints (or i/o).
@@ -431,6 +432,9 @@ struct usb_gadget_ops {
 	int	(*pullup) (struct usb_gadget *, int is_on);
 	int	(*ioctl)(struct usb_gadget *,
 				unsigned code, unsigned long param);
+	int	(*start)(struct usb_gadget_driver *,
+			int (*bind)(struct usb_gadget *));
+	int	(*stop)(struct usb_gadget_driver *);
 };
 
 /**
@@ -822,6 +826,9 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver,
  */
 int usb_gadget_unregister_driver(struct usb_gadget_driver *driver);
 
+extern int usb_add_gadget_udc(struct device *parent, struct usb_gadget *gadget);
+extern void usb_del_gadget_udc(struct usb_gadget *gadget);
+
 /*-------------------------------------------------------------------------*/
 
 /* utility to simplify dealing with string descriptors */