[PATCH v2] usb: gadget: Add uevent to notify userspace

[Baolin Wang <baolin.wang@linaro.org>]

From: Badhri Jagan Sridharan <Badhri@google.com>

Some USB managament on userspace (like Android system) rely on the uevents
generated by the composition driver to generate user notifications. Thus this
patch adds uevents to be generated whenever USB changes its state: connected,
disconnected, configured.

The original code was created by Badhri Jagan Sridharan, and I did some
optimization.

Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
Changes since v1:
 - Add Badhri's Signed-off-by.
---
 drivers/usb/gadget/Kconfig    |    8 +++
 drivers/usb/gadget/configfs.c |  107 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 115 insertions(+)

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 2ea3fc3..9f5d0c6 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -223,6 +223,14 @@ config USB_CONFIGFS
 	  appropriate symbolic links.
 	  For more information see Documentation/usb/gadget_configfs.txt.
 
+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"
+
 config USB_CONFIGFS_SERIAL
 	bool "Generic serial bulk in/out"
 	depends on USB_CONFIGFS
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 3984787..4c2bc27 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -60,6 +60,11 @@ 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;
+#endif
 };
 
 static inline struct gadget_info *to_gadget_info(struct config_item *item)
@@ -1197,6 +1202,57 @@ int composite_dev_prepare(struct usb_composite_driver *composite,
 int composite_os_desc_req_prepare(struct usb_composite_dev *cdev,
 				  struct usb_ep *ep0);
 
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+static void configfs_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 && gi->connected)
+		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 purge_configs_funcs(struct gadget_info *gi)
 {
 	struct usb_configuration	*c;
@@ -1386,13 +1442,60 @@ static void configfs_composite_unbind(struct usb_gadget *gadget)
 	set_gadget_data(gadget, NULL);
 }
 
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+static int configfs_setup(struct usb_gadget *gadget,
+			  const struct usb_ctrlrequest *c)
+{
+	struct usb_composite_dev *cdev = get_gadget_data(gadget);
+	struct gadget_info *gi = container_of(cdev, struct gadget_info, cdev);
+	int value = -EOPNOTSUPP;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cdev->lock, flags);
+	if (!gi->connected) {
+		gi->connected = 1;
+		schedule_work(&gi->work);
+	}
+	spin_unlock_irqrestore(&cdev->lock, flags);
+
+	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 configfs_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);
+	unsigned long flags;
+
+	spin_lock_irqsave(&cdev->lock, flags);
+	gi->connected = 0;
+	schedule_work(&gi->work);
+	spin_unlock_irqrestore(&cdev->lock, flags);
+
+	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          = configfs_setup,
+	.reset          = configfs_disconnect,
+	.disconnect     = configfs_disconnect,
+#else
 	.setup          = composite_setup,
 	.reset          = composite_disconnect,
 	.disconnect     = composite_disconnect,
+#endif
 
 	.suspend	= composite_suspend,
 	.resume		= composite_resume,
@@ -1453,6 +1556,10 @@ 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, configfs_work);
+#endif
+
 	if (!gi->composite.gadget_driver.function)
 		goto err;
 
-- 
1.7.9.5