USB: export autosuspend delay in sysfs
This patch (as861) adds sysfs attributes to expose the autosuspend
delay value for each USB device. If the user changes the delay from 0
(no autosuspend) to a positive value, an autosuspend is attempted.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index a420d72..9e3e943 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1225,6 +1225,26 @@
}
/**
+ * usb_try_autosuspend_device - attempt an autosuspend of a USB device and its interfaces
+ * @udev: the usb_device to autosuspend
+ *
+ * This routine should be called when a core subsystem thinks @udev may
+ * be ready to autosuspend.
+ *
+ * @udev's usage counter left unchanged. If it or any of the usage counters
+ * for an active interface is greater than 0, or autosuspend is not allowed
+ * for any other reason, no autosuspend request will be queued.
+ *
+ * This routine can run only in process context.
+ */
+void usb_try_autosuspend_device(struct usb_device *udev)
+{
+ usb_autopm_do_device(udev, 0);
+ // dev_dbg(&udev->dev, "%s: cnt %d\n",
+ // __FUNCTION__, udev->pm_usage_cnt);
+}
+
+/**
* usb_autoresume_device - immediately autoresume a USB device and its interfaces
* @udev: the usb_device to autoresume
*
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index cad4fb3..311d5df 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -158,6 +158,65 @@
}
static DEVICE_ATTR(quirks, S_IRUGO, show_quirks, NULL);
+#ifdef CONFIG_USB_SUSPEND
+
+static ssize_t
+show_autosuspend(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct usb_device *udev = to_usb_device(dev);
+
+ return sprintf(buf, "%u\n", udev->autosuspend_delay / HZ);
+}
+
+static ssize_t
+set_autosuspend(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct usb_device *udev = to_usb_device(dev);
+ unsigned value, old;
+
+ if (sscanf(buf, "%u", &value) != 1 || value >= INT_MAX/HZ)
+ return -EINVAL;
+ value *= HZ;
+
+ old = udev->autosuspend_delay;
+ udev->autosuspend_delay = value;
+ if (value > 0 && old == 0)
+ usb_try_autosuspend_device(udev);
+
+ return count;
+}
+
+static DEVICE_ATTR(autosuspend, S_IRUGO | S_IWUSR,
+ show_autosuspend, set_autosuspend);
+
+static char power_group[] = "power";
+
+static int add_power_attributes(struct device *dev)
+{
+ int rc = 0;
+
+ if (is_usb_device(dev))
+ rc = sysfs_add_file_to_group(&dev->kobj,
+ &dev_attr_autosuspend.attr,
+ power_group);
+ return rc;
+}
+
+static void remove_power_attributes(struct device *dev)
+{
+ sysfs_remove_file_from_group(&dev->kobj,
+ &dev_attr_autosuspend.attr,
+ power_group);
+}
+
+#else
+
+#define add_power_attributes(dev) 0
+#define remove_power_attributes(dev) do {} while (0)
+
+#endif /* CONFIG_USB_SUSPEND */
+
/* Descriptor fields */
#define usb_descriptor_attr_le16(field, format_string) \
static ssize_t \
@@ -230,6 +289,10 @@
if (retval)
return retval;
+ retval = add_power_attributes(dev);
+ if (retval)
+ goto error;
+
if (udev->manufacturer) {
retval = device_create_file(dev, &dev_attr_manufacturer);
if (retval)
@@ -262,6 +325,7 @@
device_remove_file(dev, &dev_attr_manufacturer);
device_remove_file(dev, &dev_attr_product);
device_remove_file(dev, &dev_attr_serial);
+ remove_power_attributes(dev);
sysfs_remove_group(&dev->kobj, &dev_attr_grp);
}
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h
index b0a35f4..08b5a04 100644
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -66,11 +66,13 @@
#ifdef CONFIG_USB_SUSPEND
extern void usb_autosuspend_device(struct usb_device *udev);
+extern void usb_try_autosuspend_device(struct usb_device *udev);
extern int usb_autoresume_device(struct usb_device *udev);
#else
-#define usb_autosuspend_device(udev) do {} while (0)
+#define usb_autosuspend_device(udev) do {} while (0)
+#define usb_try_autosuspend_device(udev) do {} while (0)
static inline int usb_autoresume_device(struct usb_device *udev)
{
return 0;
