usb: add usb2 Link PM variables to sysfs and usb_device

Adds abitilty to tune L1 timeout (inactivity timer for usb2 link sleep)
and BESL (best effort service latency)via sysfs.

This also adds a new usb2_lpm_parameters structure with those variables to
struct usb_device.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index f093e59cbe5f017531b74ce45dcc3d130ddfd44d..9759b8c913329cde110754b84438133a4738dcd7 100644 (file)
--- 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 aa38db44818a99ab9331c11d2c670669d014498f..d9284b998bd7238d13918c27094150ff80fd0c6c 100644 (file)
--- 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 3d34a0eed0880fe8254989f107224e94f98b071a..8be34f838bd45e6a854c73d4e94923bf73bb928e 100644 (file)
--- 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 fe444989668a4306feae2149c4376089ddbf2881..a232b7ece1f63c687a2f50da506c9e70ec33555e 100644 (file)
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -393,6 +393,22 @@ enum usb_port_connect_type {
        USB_PORT_NOT_USED,
 };
 
+/*
+ * 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.
  *
@@ -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;