usb: gadget: adb: Only enable the gadget when adbd is ready

When adb is enabled, only connect the gadget when adbd is ready. If adbd
dies or is restarted (e.g. "adb root"), the gadget is disconnected when
the adb device is close, and it is re-connected once adb re-open the
device.

- Add callbacks to adb, similar to FunctionFs callbacks, to notify the
  gadget when the daemon is ready or closed.
- Refcount calls to android_enable/android_disable to enable the gadget
  only once all the function daemons are ready.
- Add enable/disble to android_usb_function to notify the function when
  it is added/removed from the list of enabled functions.

Change-Id: Id54ff85aec9cf8715c94b4f9bd6137a79ad58bfc
Signed-off-by: Benoit Goby <benoit@android.com>

2 files changed, 118 insertions, 10 deletions

diff --git a/drivers/usb/gadget/android.c b/drivers/usb/gadget/android.c
index b39ae673762..d2c3393237b 100644
--- a/drivers/usb/gadget/android.c
+++ b/drivers/usb/gadget/android.c
@@ -79,6 +79,11 @@ struct android_usb_function {
 	int (*init)(struct android_usb_function *, struct usb_composite_dev *);
 	/* Optional: cleanup during gadget unbind */
 	void (*cleanup)(struct android_usb_function *);
+	/* Optional: called when the function is added the list of
+	 *		enabled functions */
+	void (*enable)(struct android_usb_function *);
+	/* Optional: called when it is removed */
+	void (*disable)(struct android_usb_function *);
 
 	int (*bind_config)(struct android_usb_function *,
 			   struct usb_configuration *);
@@ -99,6 +104,7 @@ struct android_dev {
 	struct device *dev;
 
 	bool enabled;
+	int disable_depth;
 	struct mutex mutex;
 	bool connected;
 	bool sw_connected;
@@ -183,20 +189,55 @@ static void android_work(struct work_struct *data)
 	}
 }
 
+static void android_enable(struct android_dev *dev)
+{
+	struct usb_composite_dev *cdev = dev->cdev;
+
+	if (WARN_ON(!dev->disable_depth))
+		return;
+
+	if (--dev->disable_depth == 0) {
+		usb_add_config(cdev, &android_config_driver,
+					android_bind_config);
+		usb_gadget_connect(cdev->gadget);
+	}
+}
+
+static void android_disable(struct android_dev *dev)
+{
+	struct usb_composite_dev *cdev = dev->cdev;
+
+	if (dev->disable_depth++ == 0) {
+		usb_gadget_disconnect(cdev->gadget);
+		/* Cancel pending control requests */
+		usb_ep_dequeue(cdev->gadget->ep0, cdev->req);
+		usb_remove_config(cdev, &android_config_driver);
+	}
+}
 
 /*-------------------------------------------------------------------------*/
 /* Supported functions initialization */
 
+struct adb_data {
+	bool opened;
+	bool enabled;
+};
+
 static int
 adb_function_init(struct android_usb_function *f,
 		struct usb_composite_dev *cdev)
 {
+	f->config = kzalloc(sizeof(struct adb_data), GFP_KERNEL);
+	if (!f->config)
+		return -ENOMEM;
+
 	return adb_setup();
 }
 
 static void adb_function_cleanup(struct android_usb_function *f)
 {
 	adb_cleanup();
+	kfree(f->config);
 }
 
 static int
@@ -206,13 +247,69 @@ adb_function_bind_config(struct android_usb_function *f,
 	return adb_bind_config(c);
 }
 
+static void adb_android_function_enable(struct android_usb_function *f)
+{
+	struct android_dev *dev = _android_dev;
+	struct adb_data *data = f->config;
+
+	data->enabled = true;
+
+	/* Disable the gadget until adbd is ready */
+	if (!data->opened)
+		android_disable(dev);
+}
+
+static void adb_android_function_disable(struct android_usb_function *f)
+{
+	struct android_dev *dev = _android_dev;
+	struct adb_data *data = f->config;
+
+	data->enabled = false;
+
+	/* Balance the disable that was called in closed_callback */
+	if (!data->opened)
+		android_enable(dev);
+}
+
 static struct android_usb_function adb_function = {
 	.name		= "adb",
+	.enable		= adb_android_function_enable,
+	.disable	= adb_android_function_disable,
 	.init		= adb_function_init,
 	.cleanup	= adb_function_cleanup,
 	.bind_config	= adb_function_bind_config,
 };
 
+static void adb_ready_callback(void)
+{
+	struct android_dev *dev = _android_dev;
+	struct adb_data *data = adb_function.config;
+
+	mutex_lock(&dev->mutex);
+
+	data->opened = true;
+
+	if (data->enabled)
+		android_enable(dev);
+
+	mutex_unlock(&dev->mutex);
+}
+
+static void adb_closed_callback(void)
+{
+	struct android_dev *dev = _android_dev;
+	struct adb_data *data = adb_function.config;
+
+	mutex_lock(&dev->mutex);
+
+	data->opened = false;
+
+	if (data->enabled)
+		android_disable(dev);
+
+	mutex_unlock(&dev->mutex);
+}
+
 
 #define MAX_ACM_INSTANCES 4
 struct acm_function_config {
@@ -858,6 +955,7 @@ static ssize_t enable_store(struct device *pdev, struct device_attribute *attr,
 {
 	struct android_dev *dev = dev_get_drvdata(pdev);
 	struct usb_composite_dev *cdev = dev->cdev;
+	struct android_usb_function *f;
 	int enabled = 0;
 
 
@@ -879,16 +977,18 @@ static ssize_t enable_store(struct device *pdev, struct device_attribute *attr,
 		cdev->desc.bDeviceClass = device_desc.bDeviceClass;
 		cdev->desc.bDeviceSubClass = device_desc.bDeviceSubClass;
 		cdev->desc.bDeviceProtocol = device_desc.bDeviceProtocol;
-
-		usb_add_config(cdev, &android_config_driver,
-					android_bind_config);
-		usb_gadget_connect(cdev->gadget);
+		list_for_each_entry(f, &dev->enabled_functions, enabled_list) {
+			if (f->enable)
+				f->enable(f);
+		}
+		android_enable(dev);
 		dev->enabled = true;
 	} else if (!enabled && dev->enabled) {
-		usb_gadget_disconnect(cdev->gadget);
-		/* Cancel pending control requests */
-		usb_ep_dequeue(cdev->gadget->ep0, cdev->req);
-		usb_remove_config(cdev, &android_config_driver);
+		android_disable(dev);
+		list_for_each_entry(f, &dev->enabled_functions, enabled_list) {
+			if (f->disable)
+				f->disable(f);
+		}
 		dev->enabled = false;
 	} else {
 		pr_err("android_usb: already %s\n",
@@ -1184,6 +1284,7 @@ static int __init init(void)
 	if (!dev)
 		return -ENOMEM;
 
+	dev->disable_depth = 1;
 	dev->functions = supported_functions;
 	INIT_LIST_HEAD(&dev->enabled_functions);
 	INIT_WORK(&dev->work, android_work);
diff --git a/drivers/usb/gadget/f_adb.c b/drivers/usb/gadget/f_adb.c
index 3827715f832..1629ffb5b97 100644
--- a/drivers/usb/gadget/f_adb.c
+++ b/drivers/usb/gadget/f_adb.c
@@ -111,6 +111,8 @@ static struct usb_descriptor_header *hs_adb_descs[] = {
 	NULL,
 };
 
+static void adb_ready_callback(void);
+static void adb_closed_callback(void);
 
 /* temporary variable used between adb_open() and adb_gadget_bind() */
 static struct adb_dev *_adb_dev;
@@ -407,7 +409,7 @@ static ssize_t adb_write(struct file *fp, const char __user *buf,
 
 static int adb_open(struct inode *ip, struct file *fp)
 {
-	printk(KERN_INFO "adb_open\n");
+	pr_info("adb_open\n");
 	if (!_adb_dev)
 		return -ENODEV;
 
@@ -419,12 +421,17 @@ static int adb_open(struct inode *ip, struct file *fp)
 	/* clear the error latch */
 	_adb_dev->error = 0;
 
+	adb_ready_callback();
+
 	return 0;
 }
 
 static int adb_release(struct inode *ip, struct file *fp)
 {
-	printk(KERN_INFO "adb_release\n");
+	pr_info("adb_release\n");
+
+	adb_closed_callback();
+
 	adb_unlock(&_adb_dev->open_excl);
 	return 0;
 }