usb/core: consider link speed while looking at bMaxPower

The USB 2.0 specification says that bMaxPower is the maximum power
consumption expressed in 2 mA units and the USB 3.0 specification says
that it is expressed in 8 mA units.
This patch adds a helper function usb_get_max_power() which computes the
value based on config & usb_device's speed value. The the device descriptor
dump computes the value on its own.

Cc: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/devices.c

@@ -316,17 +316,23 @@ static char *usb_dump_iad_descriptor(char *start, char *end,
  */
 static char *usb_dump_config_descriptor(char *start, char *end,
 				const struct usb_config_descriptor *desc,
-				int active)
+				int active, int speed)
 {
+	int mul;
+
 	if (start > end)
 		return start;
+	if (speed == USB_SPEED_SUPER)
+		mul = 8;
+	else
+		mul = 2;
 	start += sprintf(start, format_config,
 			 /* mark active/actual/current cfg. */
 			 active ? '*' : ' ',
 			 desc->bNumInterfaces,
 			 desc->bConfigurationValue,
 			 desc->bmAttributes,
-			 desc->bMaxPower * 2);
+			 desc->bMaxPower * mul);
 	return start;
 }
 
@@ -342,7 +348,8 @@ static char *usb_dump_config(int speed, char *start, char *end,
 	if (!config)
 		/* getting these some in 2.3.7; none in 2.3.6 */
 		return start + sprintf(start, "(null Cfg. desc.)\n");
-	start = usb_dump_config_descriptor(start, end, &config->desc, active);
+	start = usb_dump_config_descriptor(start, end, &config->desc, active,
+			speed);
 	for (i = 0; i < USB_MAXIADS; i++) {
 		if (config->intf_assoc[i] == NULL)
 			break;

drivers/usb/core/generic.c

@@ -100,7 +100,7 @@ int usb_choose_configuration(struct usb_device *udev)
 		 */
 
 		/* Rule out configs that draw too much bus current */
-		if (c->desc.bMaxPower * 2 > udev->bus_mA) {
+		if (usb_get_max_power(udev, c) > udev->bus_mA) {
 			insufficient_power++;
 			continue;
 		}

drivers/usb/core/hub.c

@@ -4211,7 +4211,7 @@ hub_power_remaining (struct usb_hub *hub)
 		/* Unconfigured devices may not use more than 100mA,
 		 * or 8mA for OTG ports */
 		if (udev->actconfig)
-			delta = udev->actconfig->desc.bMaxPower * 2;
+			delta = usb_get_max_power(udev, udev->actconfig);
 		else if (port1 != udev->bus->otg_port || hdev->parent)
 			delta = 100;
 		else

drivers/usb/core/message.c

@@ -1751,7 +1751,7 @@ int usb_set_configuration(struct usb_device *dev, int configuration)
 			}
 		}
 
-		i = dev->bus_mA - cp->desc.bMaxPower * 2;
+		i = dev->bus_mA - usb_get_max_power(dev, cp);
 		if (i < 0)
 			dev_warn(&dev->dev, "new config #%d exceeds power "
 					"limit by %dmA\n",

drivers/usb/core/sysfs.c

@@ -17,7 +17,7 @@
 #include "usb.h"
 
 /* Active configuration fields */
-#define usb_actconfig_show(field, multiplier, format_string)		\
+#define usb_actconfig_show(field, format_string)			\
 static ssize_t  show_##field(struct device *dev,			\
 		struct device_attribute *attr, char *buf)		\
 {									\
@@ -28,18 +28,31 @@ static ssize_t  show_##field(struct device *dev,			\
 	actconfig = udev->actconfig;					\
 	if (actconfig)							\
 		return sprintf(buf, format_string,			\
-				actconfig->desc.field * multiplier);	\
+				actconfig->desc.field);			\
 	else								\
 		return 0;						\
 }									\
 
-#define usb_actconfig_attr(field, multiplier, format_string)		\
+#define usb_actconfig_attr(field, format_string)		\
-usb_actconfig_show(field, multiplier, format_string)			\
+	usb_actconfig_show(field, format_string)		\
-static DEVICE_ATTR(field, S_IRUGO, show_##field, NULL);
+	static DEVICE_ATTR(field, S_IRUGO, show_##field, NULL);
 
-usb_actconfig_attr(bNumInterfaces, 1, "%2d\n")
+usb_actconfig_attr(bNumInterfaces, "%2d\n")
-usb_actconfig_attr(bmAttributes, 1, "%2x\n")
+usb_actconfig_attr(bmAttributes, "%2x\n")
-usb_actconfig_attr(bMaxPower, 2, "%3dmA\n")
+
+static ssize_t show_bMaxPower(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct usb_device *udev;
+	struct usb_host_config *actconfig;
+
+	udev = to_usb_device(dev);
+	actconfig = udev->actconfig;
+	if (!actconfig)
+		return 0;
+	return sprintf(buf, "%dmA\n", usb_get_max_power(udev, actconfig));
+}
+static DEVICE_ATTR(bMaxPower, S_IRUGO, show_bMaxPower, NULL);
 
 static ssize_t show_configuration_string(struct device *dev,
 		struct device_attribute *attr, char *buf)
@@ -56,7 +69,7 @@ static ssize_t show_configuration_string(struct device *dev,
 static DEVICE_ATTR(configuration, S_IRUGO, show_configuration_string, NULL);
 
 /* configuration value is always present, and r/w */
-usb_actconfig_show(bConfigurationValue, 1, "%u\n");
+usb_actconfig_show(bConfigurationValue, "%u\n");
 
 static ssize_t
 set_bConfigurationValue(struct device *dev, struct device_attribute *attr,

drivers/usb/core/usb.h

@@ -38,6 +38,15 @@ extern char *usb_cache_string(struct usb_device *udev, int index);
 extern int usb_set_configuration(struct usb_device *dev, int configuration);
 extern int usb_choose_configuration(struct usb_device *udev);
 
+static inline unsigned usb_get_max_power(struct usb_device *udev,
+		struct usb_host_config *c)
+{
+	/* SuperSpeed power is in 8 mA units; others are in 2 mA units */
+	unsigned mul = (udev->speed == USB_SPEED_SUPER ? 8 : 2);
+
+	return c->desc.bMaxPower * mul;
+}
+
 extern void usb_kick_khubd(struct usb_device *dev);
 extern int usb_match_one_id_intf(struct usb_device *dev,
 				 struct usb_host_interface *intf,