usbcore: add autosuspend/autoresume infrastructure

This patch (as739) adds the basic infrastructure for USB autosuspend
and autoresume.  The main features are:

	PM usage counters added to struct usb_device and struct
	usb_interface, indicating whether it's okay to autosuspend
	them or they are currently in use.

	Flag added to usb_device indicating whether the current
	suspend/resume operation originated from outside or as an
	autosuspend/autoresume.

	Flag added to usb_driver indicating whether the driver
	supports autosuspend.  If not, no device bound to the driver
	will be autosuspended.

	Mutex added to usb_device for protecting PM operations.
	Unlike the device semaphore, the locking rule for the pm_mutex
	is that you must acquire the locks going _up_ the device tree.

	New routines handling autosuspend/autoresume requests for
	interfaces and devices.

	Suspend and resume requests are propagated up the device tree
	(but not outside the USB subsystem).

	work_struct added to usb_device, for carrying out delayed
	autosuspend requests.

	Autoresume added (and autosuspend prevented) during probe and
	disconnect.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/hub.c

@@ -1017,19 +1017,22 @@ void usb_set_device_state(struct usb_device *udev,
 	if (udev->state == USB_STATE_NOTATTACHED)
 		;	/* do nothing */
 	else if (new_state != USB_STATE_NOTATTACHED) {
-		udev->state = new_state;
 
 		/* root hub wakeup capabilities are managed out-of-band
 		 * and may involve silicon errata ... ignore them here.
 		 */
 		if (udev->parent) {
-			if (new_state == USB_STATE_CONFIGURED)
+			if (udev->state == USB_STATE_SUSPENDED
+					|| new_state == USB_STATE_SUSPENDED)
+				;	/* No change to wakeup settings */
+			else if (new_state == USB_STATE_CONFIGURED)
 				device_init_wakeup(&udev->dev,
 					(udev->actconfig->desc.bmAttributes
 					 & USB_CONFIG_ATT_WAKEUP));
-			else if (new_state != USB_STATE_SUSPENDED)
+			else
 				device_init_wakeup(&udev->dev, 0);
 		}
+		udev->state = new_state;
 	} else
 		recursively_mark_NOTATTACHED(udev);
 	spin_unlock_irqrestore(&device_state_lock, flags);
@@ -1507,7 +1510,7 @@ static int hub_port_suspend(struct usb_hub *hub, int port1,
 	 * NOTE:  OTG devices may issue remote wakeup (or SRP) even when
 	 * we don't explicitly enable it here.
 	 */
-	if (device_may_wakeup(&udev->dev)) {
+	if (udev->do_remote_wakeup) {
 		status = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
 				USB_REQ_SET_FEATURE, USB_RECIP_DEVICE,
 				USB_DEVICE_REMOTE_WAKEUP, 0,
@@ -1533,7 +1536,8 @@ static int hub_port_suspend(struct usb_hub *hub, int port1,
 				USB_CTRL_SET_TIMEOUT);
 	} else {
 		/* device has up to 10 msec to fully suspend */
-		dev_dbg(&udev->dev, "usb suspend\n");
+		dev_dbg(&udev->dev, "usb %ssuspend\n",
+				udev->auto_pm ? "auto-" : "");
 		usb_set_device_state(udev, USB_STATE_SUSPENDED);
 		msleep(10);
 	}
@@ -1573,7 +1577,8 @@ static int __usb_port_suspend (struct usb_device *udev, int port1)
 		status = hub_port_suspend(hdev_to_hub(udev->parent), port1,
 				udev);
 	else {
-		dev_dbg(&udev->dev, "usb suspend\n");
+		dev_dbg(&udev->dev, "usb %ssuspend\n",
+				udev->auto_pm ? "auto-" : "");
 		usb_set_device_state(udev, USB_STATE_SUSPENDED);
 	}
 	return status;
@@ -1687,7 +1692,8 @@ hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev)
 
 		/* drive resume for at least 20 msec */
 		if (udev)
-			dev_dbg(&udev->dev, "RESUME\n");
+			dev_dbg(&udev->dev, "usb %sresume\n",
+					udev->auto_pm ? "auto-" : "");
 		msleep(25);
 
 #define LIVE_FLAGS	( USB_PORT_STAT_POWER \
@@ -1754,8 +1760,11 @@ int usb_port_resume(struct usb_device *udev)
 		// NOTE this fails if parent is also suspended...
 		status = hub_port_resume(hdev_to_hub(udev->parent),
 				udev->portnum, udev);
-	} else
+	} else {
+		dev_dbg(&udev->dev, "usb %sresume\n",
+				udev->auto_pm ? "auto-" : "");
 		status = finish_port_resume(udev);
+	}
 	if (status < 0)
 		dev_dbg(&udev->dev, "can't resume, status %d\n", status);
 	return status;
@@ -1765,19 +1774,23 @@ static int remote_wakeup(struct usb_device *udev)
 {
 	int	status = 0;
 
-	/* don't repeat RESUME sequence if this device
-	 * was already woken up by some other task
-	 */
+	/* All this just to avoid sending a port-resume message
+	 * to the parent hub! */
+
 	usb_lock_device(udev);
+	mutex_lock_nested(&udev->pm_mutex, udev->level);
 	if (udev->state == USB_STATE_SUSPENDED) {
-		dev_dbg(&udev->dev, "RESUME (wakeup)\n");
+		dev_dbg(&udev->dev, "usb %sresume\n", "wakeup-");
 		/* TRSMRCY = 10 msec */
 		msleep(10);
 		status = finish_port_resume(udev);
+		if (status == 0)
+			udev->dev.power.power_state.event = PM_EVENT_ON;
 	}
+	mutex_unlock(&udev->pm_mutex);
 
 	if (status == 0)
-		usb_resume_both(udev);
+		usb_autoresume_device(udev, 0);
 	usb_unlock_device(udev);
 	return status;
 }
@@ -1834,7 +1847,9 @@ static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
 					== PM_EVENT_ON
 #endif
 				) {
-			dev_dbg(&intf->dev, "port %d nyet suspended\n", port1);
+			if (!hdev->auto_pm)
+				dev_dbg(&intf->dev, "port %d nyet suspended\n",
+						port1);
 			return -EBUSY;
 		}
 	}
@@ -2587,7 +2602,7 @@ static void hub_events(void)
 		 * stub "device" node was never suspended.
 		 */
 		if (i)
-			usb_resume_both(hdev);
+			usb_autoresume_device(hdev, 0);
 
 		/* If this is an inactive or suspended hub, do nothing */
 		if (hub->quiescing)
@@ -2993,6 +3008,9 @@ int usb_reset_composite_device(struct usb_device *udev,
 		return -EINVAL;
 	}
 
+	/* Prevent autosuspend during the reset */
+	usb_autoresume_device(udev, 1);
+
 	if (iface && iface->condition != USB_INTERFACE_BINDING)
 		iface = NULL;
 
@@ -3034,6 +3052,7 @@ int usb_reset_composite_device(struct usb_device *udev,
 		}
 	}
 
+	usb_autosuspend_device(udev, 1);
 	return ret;
 }
 EXPORT_SYMBOL(usb_reset_composite_device);

drivers/usb/core/usb.c

@@ -168,6 +168,10 @@ static void usb_release_dev(struct device *dev)
 
 	udev = to_usb_device(dev);
 
+#ifdef	CONFIG_PM
+	cancel_delayed_work(&udev->autosuspend);
+	flush_scheduled_work();
+#endif
 	usb_destroy_configuration(udev);
 	usb_put_hcd(bus_to_hcd(udev->bus));
 	kfree(udev->product);
@@ -176,6 +180,21 @@ static void usb_release_dev(struct device *dev)
 	kfree(udev);
 }
 
+#ifdef	CONFIG_PM
+
+/* usb_autosuspend_work - callback routine to autosuspend a USB device */
+static void usb_autosuspend_work(void *_udev)
+{
+	struct usb_device	*udev = _udev;
+
+	mutex_lock_nested(&udev->pm_mutex, udev->level);
+	udev->auto_pm = 1;
+	usb_suspend_both(udev, PMSG_SUSPEND);
+	mutex_unlock(&udev->pm_mutex);
+}
+
+#endif
+
 /**
  * usb_alloc_dev - usb device constructor (usbcore-internal)
  * @parent: hub to which device is connected; null to allocate a root hub
@@ -251,6 +270,10 @@ usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
 	dev->parent = parent;
 	INIT_LIST_HEAD(&dev->filelist);
 
+#ifdef	CONFIG_PM
+	mutex_init(&dev->pm_mutex);
+	INIT_WORK(&dev->autosuspend, usb_autosuspend_work, dev);
+#endif
 	return dev;
 }
 

drivers/usb/core/usb.h

@@ -49,6 +49,20 @@ static inline int usb_resume_both(struct usb_device *udev)
 
 #endif
 
+#ifdef CONFIG_USB_SUSPEND
+
+#define USB_AUTOSUSPEND_DELAY	(HZ*2)
+
+extern void usb_autosuspend_device(struct usb_device *udev, int dec_busy_cnt);
+extern int usb_autoresume_device(struct usb_device *udev, int inc_busy_cnt);
+
+#else
+
+#define usb_autosuspend_device(udev, dec_busy_cnt)	do {} while (0)
+#define usb_autoresume_device(udev, inc_busy_cnt)	0
+
+#endif
+
 extern struct bus_type usb_bus_type;
 extern struct usb_device_driver usb_generic_driver;
 

include/linux/usb.h

@@ -19,6 +19,7 @@
 #include <linux/fs.h>		/* for struct file_operations */
 #include <linux/completion.h>	/* for struct completion */
 #include <linux/sched.h>	/* for current && schedule_timeout */
+#include <linux/mutex.h>	/* for struct mutex */
 
 struct usb_device;
 struct usb_driver;
@@ -103,8 +104,12 @@ enum usb_interface_condition {
  * @condition: binding state of the interface: not bound, binding
  *	(in probe()), bound to a driver, or unbinding (in disconnect())
  * @is_active: flag set when the interface is bound and not suspended.
+ * @needs_remote_wakeup: flag set when the driver requires remote-wakeup
+ *	capability during autosuspend.
  * @dev: driver model's view of this device
  * @class_dev: driver model's class view of this device.
+ * @pm_usage_cnt: PM usage counter for this interface; autosuspend is not
+ *	allowed unless the counter is 0.
  *
  * USB device drivers attach to interfaces on a physical device.  Each
  * interface encapsulates a single high level function, such as feeding
@@ -144,9 +149,11 @@ struct usb_interface {
 					 * bound to */
 	enum usb_interface_condition condition;		/* state of binding */
 	unsigned is_active:1;		/* the interface is not suspended */
+	unsigned needs_remote_wakeup:1;	/* driver requires remote wakeup */
 
 	struct device dev;		/* interface specific device info */
 	struct class_device *class_dev;
+	int pm_usage_cnt;		/* usage counter for autosuspend */
 };
 #define	to_usb_interface(d) container_of(d, struct usb_interface, dev)
 #define	interface_to_usbdev(intf) \
@@ -372,6 +379,15 @@ struct usb_device {
 
 	int maxchild;			/* Number of ports if hub */
 	struct usb_device *children[USB_MAXCHILDREN];
+
+#ifdef CONFIG_PM
+	struct work_struct autosuspend;	/* for delayed autosuspends */
+	struct mutex pm_mutex;		/* protects PM operations */
+	int pm_usage_cnt;		/* usage counter for autosuspend */
+
+	unsigned auto_pm:1;		/* autosuspend/resume in progress */
+	unsigned do_remote_wakeup:1;	/* remote wakeup should be enabled */
+#endif
 };
 #define	to_usb_device(d) container_of(d, struct usb_device, dev)
 
@@ -392,6 +408,17 @@ extern int usb_reset_composite_device(struct usb_device *dev,
 
 extern struct usb_device *usb_find_device(u16 vendor_id, u16 product_id);
 
+/* USB autosuspend and autoresume */
+#ifdef CONFIG_USB_SUSPEND
+extern int usb_autopm_get_interface(struct usb_interface *intf);
+extern void usb_autopm_put_interface(struct usb_interface *intf);
+
+#else
+#define usb_autopm_get_interface(intf)		0
+#define usb_autopm_put_interface(intf)		do {} while (0)
+#endif
+
+
 /*-------------------------------------------------------------------------*/
 
 /* for drivers using iso endpoints */
@@ -593,6 +620,8 @@ struct usbdrv_wrap {
  * @drvwrap: Driver-model core structure wrapper.
  * @no_dynamic_id: if set to 1, the USB core will not allow dynamic ids to be
  *	added to this driver by preventing the sysfs file from being created.
+ * @supports_autosuspend: if set to 0, the USB core will not allow autosuspend
+ *	for interfaces bound to this driver.
  *
  * USB interface drivers must provide a name, probe() and disconnect()
  * methods, and an id_table.  Other driver fields are optional.
@@ -631,6 +660,7 @@ struct usb_driver {
 	struct usb_dynids dynids;
 	struct usbdrv_wrap drvwrap;
 	unsigned int no_dynamic_id:1;
+	unsigned int supports_autosuspend:1;
 };
 #define	to_usb_driver(d) container_of(d, struct usb_driver, drvwrap.driver)
 
@@ -648,6 +678,8 @@ struct usb_driver {
  * @suspend: Called when the device is going to be suspended by the system.
  * @resume: Called when the device is being resumed by the system.
  * @drvwrap: Driver-model core structure wrapper.
+ * @supports_autosuspend: if set to 0, the USB core will not allow autosuspend
+ *	for devices bound to this driver.
  *
  * USB drivers must provide all the fields listed above except drvwrap.
  */
@@ -660,6 +692,7 @@ struct usb_device_driver {
 	int (*suspend) (struct usb_device *udev, pm_message_t message);
 	int (*resume) (struct usb_device *udev);
 	struct usbdrv_wrap drvwrap;
+	unsigned int supports_autosuspend:1;
 };
 #define	to_usb_device_driver(d) container_of(d, struct usb_device_driver, \
 		drvwrap.driver)