usb: add helper to extract bits 12:11 of wMaxPacketSize (541b6fe6) · Commits · 戴 / test

According to USB Specification 2.0 table 9-4, wMaxPacketSize is a bitfield. Endpoint's maxpacket is laid out in bits 10:0. For high-speed, high-bandwidth isochronous endpoints, bits 12:11 contain a multiplier to tell us how many transactions we want to try per uframe. This means that if we want an isochronous endpoint to issue 3 transfers of 1024 bytes per uframe, wMaxPacketSize should contain the value: 1024 | (2 << 11) or 5120 (0x1400). In order to make Host and Peripheral controller drivers' life easier, we're adding a helper which returns bits 12:11. Note that no care is made WRT to checking endpoint type and gadget's speed. That's left for drivers to handle. Signed-off-by:

Felipe Balbi <felipe.balbi@linux.intel.com>

include/uapi/linux/usb/ch9.h

+19 −0

Original line number	Diff line number	Diff line
		@@ -423,6 +423,11 @@ struct usb_endpoint_descriptor {
		#define USB_ENDPOINT_XFER_INT 3
		#define USB_ENDPOINT_MAX_ADJUSTABLE 0x80

		#define USB_EP_MAXP_MULT_SHIFT 11
		#define USB_EP_MAXP_MULT_MASK (3 << USB_EP_MAXP_MULT_SHIFT)
		#define USB_EP_MAXP_MULT(m) \
		(((m) & USB_EP_MAXP_MULT_MASK) >> USB_EP_MAXP_MULT_SHIFT)

		/* The USB 3.0 spec redefines bits 5:4 of bmAttributes as interrupt ep type. */
		#define USB_ENDPOINT_INTRTYPE 0x30
		#define USB_ENDPOINT_INTR_PERIODIC (0 << 4)
		@@ -630,6 +635,20 @@ static inline int usb_endpoint_maxp(const struct usb_endpoint_descriptor *epd)
		return __le16_to_cpu(epd->wMaxPacketSize);
		}

		/**
		* usb_endpoint_maxp_mult - get endpoint's transactional opportunities
		* @epd: endpoint to be checked
		*
		* Return @epd's wMaxPacketSize[12:11] + 1
		*/
		static inline int
		usb_endpoint_maxp_mult(const struct usb_endpoint_descriptor *epd)
		{
		int maxp = __le16_to_cpu(epd->wMaxPacketSize);

		return USB_EP_MAXP_MULT(maxp) + 1;
		}

		static inline int usb_endpoint_interrupt_type(
		const struct usb_endpoint_descriptor *epd)
		{

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