1 files changed, 76 insertions, 0 deletions

diff --git a/drivers/usb/common/common.c b/drivers/usb/common/common.c
index fc21cf2d36f6..347fb3d3894a 100644
--- a/drivers/usb/common/common.c
+++ b/drivers/usb/common/common.c
@@ -25,6 +25,12 @@ static const char *const ep_type_names[] = {
 	[USB_ENDPOINT_XFER_INT] = "intr",
 };
 
+/**
+ * usb_ep_type_string() - Returns human readable-name of the endpoint type.
+ * @ep_type: The endpoint type to return human-readable name for.  If it's not
+ *   any of the types: USB_ENDPOINT_XFER_{CONTROL, ISOC, BULK, INT},
+ *   usually got by usb_endpoint_type(), the string 'unknown' will be returned.
+ */
 const char *usb_ep_type_string(int ep_type)
 {
 	if (ep_type < 0 || ep_type >= ARRAY_SIZE(ep_type_names))
@@ -76,6 +82,12 @@ static const char *const ssp_rate[] = {
 	[USB_SSP_GEN_2x2] = "super-speed-plus-gen2x2",
 };
 
+/**
+ * usb_speed_string() - Returns human readable-name of the speed.
+ * @speed: The speed to return human-readable name for.  If it's not
+ *   any of the speeds defined in usb_device_speed enum, string for
+ *   USB_SPEED_UNKNOWN will be returned.
+ */
 const char *usb_speed_string(enum usb_device_speed speed)
 {
 	if (speed < 0 || speed >= ARRAY_SIZE(speed_names))
@@ -84,6 +96,14 @@ const char *usb_speed_string(enum usb_device_speed speed)
 }
 EXPORT_SYMBOL_GPL(usb_speed_string);
 
+/**
+ * usb_get_maximum_speed - Get maximum requested speed for a given USB
+ * controller.
+ * @dev: Pointer to the given USB controller device
+ *
+ * The function gets the maximum speed string from property "maximum-speed",
+ * and returns the corresponding enum usb_device_speed.
+ */
 enum usb_device_speed usb_get_maximum_speed(struct device *dev)
 {
 	const char *maximum_speed;
@@ -102,6 +122,15 @@ enum usb_device_speed usb_get_maximum_speed(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(usb_get_maximum_speed);
 
+/**
+ * usb_get_maximum_ssp_rate - Get the signaling rate generation and lane count
+ *	of a SuperSpeed Plus capable device.
+ * @dev: Pointer to the given USB controller device
+ *
+ * If the string from "maximum-speed" property is super-speed-plus-genXxY where
+ * 'X' is the generation number and 'Y' is the number of lanes, then this
+ * function returns the corresponding enum usb_ssp_rate.
+ */
 enum usb_ssp_rate usb_get_maximum_ssp_rate(struct device *dev)
 {
 	const char *maximum_speed;
@@ -116,6 +145,12 @@ enum usb_ssp_rate usb_get_maximum_ssp_rate(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(usb_get_maximum_ssp_rate);
 
+/**
+ * usb_state_string - Returns human readable name for the state.
+ * @state: The state to return a human-readable name for. If it's not
+ *	any of the states devices in usb_device_state_string enum,
+ *	the string UNKNOWN will be returned.
+ */
 const char *usb_state_string(enum usb_device_state state)
 {
 	static const char *const names[] = {
@@ -165,6 +200,47 @@ enum usb_dr_mode usb_get_dr_mode(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(usb_get_dr_mode);
 
+/**
+ * usb_decode_interval - Decode bInterval into the time expressed in 1us unit
+ * @epd: The descriptor of the endpoint
+ * @speed: The speed that the endpoint works as
+ *
+ * Function returns the interval expressed in 1us unit for servicing
+ * endpoint for data transfers.
+ */
+unsigned int usb_decode_interval(const struct usb_endpoint_descriptor *epd,
+				 enum usb_device_speed speed)
+{
+	unsigned int interval = 0;
+
+	switch (usb_endpoint_type(epd)) {
+	case USB_ENDPOINT_XFER_CONTROL:
+		/* uframes per NAK */
+		if (speed == USB_SPEED_HIGH)
+			interval = epd->bInterval;
+		break;
+	case USB_ENDPOINT_XFER_ISOC:
+		interval = 1 << (epd->bInterval - 1);
+		break;
+	case USB_ENDPOINT_XFER_BULK:
+		/* uframes per NAK */
+		if (speed == USB_SPEED_HIGH && usb_endpoint_dir_out(epd))
+			interval = epd->bInterval;
+		break;
+	case USB_ENDPOINT_XFER_INT:
+		if (speed >= USB_SPEED_HIGH)
+			interval = 1 << (epd->bInterval - 1);
+		else
+			interval = epd->bInterval;
+		break;
+	}
+
+	interval *= (speed >= USB_SPEED_HIGH) ? 125 : 1000;
+
+	return interval;
+}
+EXPORT_SYMBOL_GPL(usb_decode_interval);
+
 #ifdef CONFIG_OF
 /**
  * of_usb_get_dr_mode_by_phy - Get dual role mode for the controller device