usb: gadget: consider link speed for 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 renames bMaxPower to MaxPower and the various /2 and *2 are
removed. Before reporting the config descriptor, the proper value is
computer based on the speed, all in-tree users are updated. MaxPower is
also increased to u16 so we can store the nokia gadget value which is
larger than the max value allowed for u8.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/composite.c

@@ -320,6 +320,25 @@ int usb_interface_id(struct usb_configuration *config,
 }
 EXPORT_SYMBOL_GPL(usb_interface_id);
 
+static u8 encode_bMaxPower(enum usb_device_speed speed,
+		struct usb_configuration *c)
+{
+	unsigned val;
+
+	if (c->MaxPower)
+		val = c->MaxPower;
+	else
+		val = CONFIG_USB_GADGET_VBUS_DRAW;
+	if (!val)
+		return 0;
+	switch (speed) {
+	case USB_SPEED_SUPER:
+		return DIV_ROUND_UP(val, 8);
+	default:
+		return DIV_ROUND_UP(val, 2);
+	};
+}
+
 static int config_buf(struct usb_configuration *config,
 		enum usb_device_speed speed, void *buf, u8 type)
 {
@@ -339,7 +358,7 @@ static int config_buf(struct usb_configuration *config,
 	c->bConfigurationValue = config->bConfigurationValue;
 	c->iConfiguration = config->iConfiguration;
 	c->bmAttributes = USB_CONFIG_ATT_ONE | config->bmAttributes;
-	c->bMaxPower = config->bMaxPower ? : (CONFIG_USB_GADGET_VBUS_DRAW / 2);
+	c->bMaxPower = encode_bMaxPower(speed, config);
 
 	/* There may be e.g. OTG descriptors */
 	if (config->descriptors) {
@@ -656,7 +675,7 @@ static int set_config(struct usb_composite_dev *cdev,
 	}
 
 	/* when we return, be sure our power usage is valid */
-	power = c->bMaxPower ? (2 * c->bMaxPower) : CONFIG_USB_GADGET_VBUS_DRAW;
+	power = c->MaxPower ? c->MaxPower : CONFIG_USB_GADGET_VBUS_DRAW;
 done:
 	usb_gadget_vbus_draw(gadget, power);
 	if (result >= 0 && cdev->delayed_status)
@@ -1518,10 +1537,10 @@ composite_resume(struct usb_gadget *gadget)
 				f->resume(f);
 		}
 
-		maxpower = cdev->config->bMaxPower;
+		maxpower = cdev->config->MaxPower;
 
 		usb_gadget_vbus_draw(gadget, maxpower ?
-			(2 * maxpower) : CONFIG_USB_GADGET_VBUS_DRAW);
+			maxpower : CONFIG_USB_GADGET_VBUS_DRAW);
 	}
 
 	cdev->suspended = 0;

drivers/usb/gadget/gmidi.c

@@ -125,7 +125,7 @@ static struct usb_configuration midi_config = {
 	.bConfigurationValue = 1,
 	/* .iConfiguration = DYNAMIC */
 	.bmAttributes	= USB_CONFIG_ATT_ONE,
-	.bMaxPower	= CONFIG_USB_GADGET_VBUS_DRAW / 2,
+	.MaxPower	= CONFIG_USB_GADGET_VBUS_DRAW,
 };
 
 static int __init midi_bind_config(struct usb_configuration *c)

drivers/usb/gadget/nokia.c

@@ -133,15 +133,15 @@ static struct usb_configuration nokia_config_500ma_driver = {
 	.bConfigurationValue = 1,
 	/* .iConfiguration = DYNAMIC */
 	.bmAttributes	= USB_CONFIG_ATT_ONE,
-	.bMaxPower	= 250, /* 500mA */
+	.MaxPower	= 500,
 };
 
 static struct usb_configuration nokia_config_100ma_driver = {
 	.label		= "Self Powered",
 	.bConfigurationValue = 2,
 	/* .iConfiguration = DYNAMIC */
 	.bmAttributes	= USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER,
-	.bMaxPower	= 50, /* 100 mA */
+	.MaxPower	= 100,
 };
 
 static int __init nokia_bind(struct usb_composite_dev *cdev)

drivers/usb/gadget/webcam.c

@@ -336,7 +336,7 @@ static struct usb_configuration webcam_config_driver = {
 	.bConfigurationValue	= 1,
 	.iConfiguration		= 0, /* dynamic */
 	.bmAttributes		= USB_CONFIG_ATT_SELFPOWER,
-	.bMaxPower		= CONFIG_USB_GADGET_VBUS_DRAW / 2,
+	.MaxPower		= CONFIG_USB_GADGET_VBUS_DRAW,
 };
 
 static int /* __init_or_exit */

include/linux/usb/composite.h

@@ -184,7 +184,8 @@ int config_ep_by_speed(struct usb_gadget *g, struct usb_function *f,
  * @bConfigurationValue: Copied into configuration descriptor.
  * @iConfiguration: Copied into configuration descriptor.
  * @bmAttributes: Copied into configuration descriptor.
- * @bMaxPower: Copied into configuration descriptor.
+ * @MaxPower: Power consumtion in mA. Used to compute bMaxPower in the
+ *	configuration descriptor after considering the bus speed.
  * @cdev: assigned by @usb_add_config() before calling @bind(); this is
  *	the device associated with this configuration.
  *
@@ -230,7 +231,7 @@ struct usb_configuration {
 	u8			bConfigurationValue;
 	u8			iConfiguration;
 	u8			bmAttributes;
-	u8			bMaxPower;
+	u16			MaxPower;
 
 	struct usb_composite_dev	*cdev;