4 files changed, 103 insertions, 2 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index f093e59cbe5f..9759b8c91332 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -236,3 +236,30 @@ Description:
                 This attribute is to expose these information to user space.
                 The file will read "hotplug", "wired" and "not used" if the
                 information is available, and "unknown" otherwise.
+
+What:           /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
+Date:           May 2013
+Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
+Description:
+                USB 2.0 devices may support hardware link power management (LPM)
+                L1 sleep state. The usb2_lpm_l1_timeout attribute allows
+                tuning the timeout for L1 inactivity timer (LPM timer), e.g.
+                needed inactivity time before host requests the device to go to L1 sleep.
+                Useful for power management tuning.
+                Supported values are 0 - 65535 microseconds.
+
+What:           /sys/bus/usb/devices/.../power/usb2_lpm_besl
+Date:           May 2013
+Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
+Description:
+                USB 2.0 devices that support hardware link power management (LPM)
+                L1 sleep state now use a best effort service latency value (BESL) to
+                indicate the best effort to resumption of service to the device after the
+                initiation of the resume event.
+                If the device does not have a preferred besl value then the host can select
+                one instead. This usb2_lpm_besl attribute allows to tune the host selected besl
+                value in order to tune power saving and service latency.
+
+                Supported values are 0 - 15.
+                More information on how besl values map to microseconds can be found in
+                USB 2.0 ECN Errata for Link Power Management, section 4.10)
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index aa38db44818a..d9284b998bd7 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -497,8 +497,62 @@ set_usb2_hardware_lpm(struct device *dev, struct device_attribute *attr,
 static DEVICE_ATTR(usb2_hardware_lpm, S_IRUGO | S_IWUSR, show_usb2_hardware_lpm,
                         set_usb2_hardware_lpm);
 
+static ssize_t
+show_usb2_lpm_l1_timeout(struct device *dev, struct device_attribute *attr,
+                         char *buf)
+{
+        struct usb_device *udev = to_usb_device(dev);
+        return sprintf(buf, "%d\n", udev->l1_params.timeout);
+}
+
+static ssize_t
+set_usb2_lpm_l1_timeout(struct device *dev, struct device_attribute *attr,
+                        const char *buf, size_t count)
+{
+        struct usb_device *udev = to_usb_device(dev);
+        u16 timeout;
+
+        if (kstrtou16(buf, 0, &timeout))
+                return -EINVAL;
+
+        udev->l1_params.timeout = timeout;
+
+        return count;
+}
+
+static DEVICE_ATTR(usb2_lpm_l1_timeout, S_IRUGO | S_IWUSR,
+                   show_usb2_lpm_l1_timeout, set_usb2_lpm_l1_timeout);
+
+static ssize_t
+show_usb2_lpm_besl(struct device *dev, struct device_attribute *attr,
+                   char *buf)
+{
+        struct usb_device *udev = to_usb_device(dev);
+        return sprintf(buf, "%d\n", udev->l1_params.besl);
+}
+
+static ssize_t
+set_usb2_lpm_besl(struct device *dev, struct device_attribute *attr,
+                const char *buf, size_t count)
+{
+        struct usb_device *udev = to_usb_device(dev);
+        u8 besl;
+
+        if (kstrtou8(buf, 0, &besl) || besl > 15)
+                return -EINVAL;
+
+        udev->l1_params.besl = besl;
+
+        return count;
+}
+
+static DEVICE_ATTR(usb2_lpm_besl, S_IRUGO | S_IWUSR,
+                   show_usb2_lpm_besl, set_usb2_lpm_besl);
+
 static struct attribute *usb2_hardware_lpm_attr[] = {
         &dev_attr_usb2_hardware_lpm.attr,
+        &dev_attr_usb2_lpm_l1_timeout.attr,
+        &dev_attr_usb2_lpm_besl.attr,
         NULL,
 };
 static struct attribute_group usb2_hardware_lpm_attr_group = {
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 3d34a0eed088..8be34f838bd4 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3917,7 +3917,7 @@ static int xhci_calculate_usb2_hw_lpm_params(struct usb_device *udev)
         field = le32_to_cpu(udev->bos->ext_cap->bmAttributes);
 
         /* xHCI l1 is set in steps of 256us, xHCI 1.0 section 5.4.11.2 */
-        l1 = XHCI_L1_TIMEOUT / 256;
+        l1 = udev->l1_params.timeout / 256;
 
         /* device has preferred BESLD */
         if (field & USB_BESL_DEEP_VALID) {
@@ -4101,7 +4101,7 @@ int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
                             (field & USB_BESL_BASELINE_VALID))
                                 hird = USB_GET_BESL_BASELINE(field);
                         else
-                                hird = XHCI_DEFAULT_BESL;
+                                hird = udev->l1_params.besl;
 
                         exit_latency = xhci_besl_encoding[hird];
                         spin_unlock_irqrestore(&xhci->lock, flags);
@@ -4191,6 +4191,8 @@ int xhci_update_device(struct usb_hcd *hcd, struct usb_device *udev)
                 if (xhci->hw_lpm_support == 1 &&
                     xhci_check_usb2_port_capability(xhci, portnum, XHCI_HLC)) {
                         udev->usb2_hw_lpm_capable = 1;
+                        udev->l1_params.timeout = XHCI_L1_TIMEOUT;
+                        udev->l1_params.besl = XHCI_DEFAULT_BESL;
                         if (xhci_check_usb2_port_capability(xhci, portnum,
                                                             XHCI_BLC))
                                 udev->usb2_hw_lpm_besl_capable = 1;
diff --git a/include/linux/usb.h b/include/linux/usb.h
index fe444989668a..a232b7ece1f6 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -394,6 +394,22 @@ enum usb_port_connect_type {
 };
 
 /*
+ * USB 2.0 Link Power Management (LPM) parameters.
+ */
+struct usb2_lpm_parameters {
+        /* Best effort service latency indicate how long the host will drive
+         * resume on an exit from L1.
+         */
+        unsigned int besl;
+
+        /* Timeout value in microseconds for the L1 inactivity (LPM) timer.
+         * When the timer counts to zero, the parent hub will initiate a LPM
+         * transition to L1.
+         */
+        int timeout;
+};
+
+/*
  * USB 3.0 Link Power Management (LPM) parameters.
  *
  * PEL and SEL are USB 3.0 Link PM latencies for device-initiated LPM exit.
@@ -488,6 +504,7 @@ struct usb3_lpm_parameters {
  *      specific data for the device.
  * @slot_id: Slot ID assigned by xHCI
  * @removable: Device can be physically removed from this port
+ * @l1_params: best effor service latency for USB2 L1 LPM state, and L1 timeout.
  * @u1_params: exit latencies for USB3 U1 LPM state, and hub-initiated timeout.
  * @u2_params: exit latencies for USB3 U2 LPM state, and hub-initiated timeout.
  * @lpm_disable_count: Ref count used by usb_disable_lpm() and usb_enable_lpm()
@@ -568,6 +585,7 @@ struct usb_device {
         struct wusb_dev *wusb_dev;
         int slot_id;
         enum usb_device_removable removable;
+        struct usb2_lpm_parameters l1_params;
         struct usb3_lpm_parameters u1_params;
         struct usb3_lpm_parameters u2_params;
         unsigned lpm_disable_count;