usb: gadget: Add Uevent to notify userspace

Android userspace UsbDeviceManager relies on the
uevents generated by the composition driver to
generate user notifications. This CL adds uevents
to be generated whenever USB changes its state
i.e. connected, disconnected, configured.

This CL also intercepts the setup requests from
the usb_core anb routes it to the specific
usb function if required.

Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
Change-Id: Ib3d3a78255a532f7449dac286f776c2966caf8c1
[AmitP: Cherry-picked it from android-3.18 to flo mainline kernel,
        and removed Android accessory related changes.]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>

Conflicts:
	drivers/usb/gadget/Kconfig
	drivers/usb/gadget/configfs.c

2 files changed, 141 insertions, 2 deletions

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 98a41d9143e6..bd95d688b769 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -471,6 +471,14 @@ config USB_CONFIGFS_F_PTP
         help
           USB gadget PTP support
 
+config USB_CONFIGFS_UEVENT
+	boolean "Uevent notification of Gadget state"
+	depends on USB_CONFIGFS
+	help
+	  Enable uevent notifications to userspace when the gadget
+	  state changes. The gadget can be in any of the following
+	  three states: "CONNECTED/DISCONNECTED/CONFIGURED"
+
 source "drivers/usb/gadget/legacy/Kconfig"
 
 endchoice
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 289e20119fea..39183209e75a 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -9,6 +9,15 @@
 #include "u_f.h"
 #include "u_os_desc.h"
 
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+#include <linux/platform_device.h>
+#include <linux/kdev_t.h>
+#include <linux/usb/ch9.h>
+#include "u_fs.h"
+
+static struct class *android_class;
+#endif
+
 int check_user_usb_string(const char *name,
 		struct usb_gadget_strings *stringtab_dev)
 {
@@ -63,6 +72,12 @@ struct gadget_info {
 	bool use_os_desc;
 	char b_vendor_code;
 	char qw_sign[OS_STRING_QW_SIGN_LEN];
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+	bool connected;
+	bool sw_connected;
+	struct work_struct work;
+	struct device *dev;
+#endif
 };
 
 struct config_usb_cfg {
@@ -262,7 +277,7 @@ static ssize_t gadget_dev_desc_UDC_store(struct gadget_info *gi,
 
 	mutex_lock(&gi->lock);
 
-	if (!strlen(name)) {
+	if (!strlen(name) || strcmp(name, "none") == 0) {
 		ret = unregister_gadget(gi);
 		if (ret)
 			goto err;
@@ -1427,6 +1442,57 @@ err_comp_cleanup:
 	return ret;
 }
 
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+static void android_work(struct work_struct *data)
+{
+	struct gadget_info *gi = container_of(data, struct gadget_info, work);
+	struct usb_composite_dev *cdev = &gi->cdev;
+	char *disconnected[2] = { "USB_STATE=DISCONNECTED", NULL };
+	char *connected[2]    = { "USB_STATE=CONNECTED", NULL };
+	char *configured[2]   = { "USB_STATE=CONFIGURED", NULL };
+	/* 0-connected 1-configured 2-disconnected*/
+	bool status[3] = { false, false, false };
+	unsigned long flags;
+	bool uevent_sent = false;
+
+	spin_lock_irqsave(&cdev->lock, flags);
+	if (cdev->config)
+		status[1] = true;
+
+	if (gi->connected != gi->sw_connected) {
+		if (gi->connected)
+			status[0] = true;
+		else
+			status[2] = true;
+		gi->sw_connected = gi->connected;
+	}
+	spin_unlock_irqrestore(&cdev->lock, flags);
+
+	if (status[0]) {
+		kobject_uevent_env(&gi->dev->kobj, KOBJ_CHANGE, connected);
+		pr_info("%s: sent uevent %s\n", __func__, connected[0]);
+		uevent_sent = true;
+	}
+
+	if (status[1]) {
+		kobject_uevent_env(&gi->dev->kobj, KOBJ_CHANGE, configured);
+		pr_info("%s: sent uevent %s\n", __func__, configured[0]);
+		uevent_sent = true;
+	}
+
+	if (status[2]) {
+		kobject_uevent_env(&gi->dev->kobj, KOBJ_CHANGE, disconnected);
+		pr_info("%s: sent uevent %s\n", __func__, disconnected[0]);
+		uevent_sent = true;
+	}
+
+	if (!uevent_sent) {
+		pr_info("%s: did not send uevent (%d %d %p)\n", __func__,
+			gi->connected, gi->sw_connected, cdev->config);
+	}
+}
+#endif
+
 static void configfs_composite_unbind(struct usb_gadget *gadget)
 {
 	struct usb_composite_dev	*cdev;
@@ -1444,13 +1510,65 @@ static void configfs_composite_unbind(struct usb_gadget *gadget)
 	set_gadget_data(gadget, NULL);
 }
 
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+static int android_setup(struct usb_gadget *gadget,
+			const struct usb_ctrlrequest *c)
+{
+	struct usb_composite_dev *cdev = get_gadget_data(gadget);
+	unsigned long flags;
+	struct gadget_info *gi = container_of(cdev, struct gadget_info, cdev);
+	int value = -EOPNOTSUPP;
+	struct usb_function_instance *fi;
+
+	spin_lock_irqsave(&cdev->lock, flags);
+	if (!gi->connected) {
+		gi->connected = 1;
+		schedule_work(&gi->work);
+	}
+	spin_unlock_irqrestore(&cdev->lock, flags);
+	list_for_each_entry(fi, &gi->available_func, cfs_list) {
+		if (fi != NULL && fi->f != NULL && fi->f->setup != NULL) {
+			value = fi->f->setup(fi->f, c);
+			if (value >= 0)
+				break;
+		}
+	}
+
+	if (value < 0)
+		value = composite_setup(gadget, c);
+
+	spin_lock_irqsave(&cdev->lock, flags);
+	if (c->bRequest == USB_REQ_SET_CONFIGURATION &&
+						cdev->config) {
+		schedule_work(&gi->work);
+	}
+	spin_unlock_irqrestore(&cdev->lock, flags);
+
+	return value;
+}
+
+static void android_disconnect(struct usb_gadget *gadget)
+{
+	struct usb_composite_dev        *cdev = get_gadget_data(gadget);
+	struct gadget_info *gi = container_of(cdev, struct gadget_info, cdev);
+
+	gi->connected = 0;
+	schedule_work(&gi->work);
+	composite_disconnect(gadget);
+}
+#endif
+
 static const struct usb_gadget_driver configfs_driver_template = {
 	.bind           = configfs_composite_bind,
 	.unbind         = configfs_composite_unbind,
-
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+	.setup          = android_setup,
+	.disconnect     = android_disconnect,
+#else
 	.setup          = composite_setup,
 	.reset          = composite_disconnect,
 	.disconnect     = composite_disconnect,
+#endif
 
 	.suspend	= composite_suspend,
 	.resume		= composite_resume,
@@ -1507,6 +1625,12 @@ static struct config_group *gadgets_make(
 	gi->composite.gadget_driver.function = kstrdup(name, GFP_KERNEL);
 	gi->composite.name = gi->composite.gadget_driver.function;
 
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+	INIT_WORK(&gi->work, android_work);
+	gi->dev = device_create(android_class, NULL,
+				MKDEV(0, 0), NULL, "android0");
+#endif
+
 	if (!gi->composite.gadget_driver.function)
 		goto err;
 
@@ -1564,6 +1688,13 @@ static int __init gadget_cfs_init(void)
 	config_group_init(&gadget_subsys.su_group);
 
 	ret = configfs_register_subsystem(&gadget_subsys);
+
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+	android_class = class_create(THIS_MODULE, "android_usb");
+	if (IS_ERR(android_class))
+		return PTR_ERR(android_class);
+#endif
+
 	return ret;
 }
 module_init(gadget_cfs_init);