From: Felipe Balbi Date: Mon, 26 Sep 2016 07:51:18 +0000 (+0300) Subject: usb: add helper to extract bits 12:11 of wMaxPacketSize X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=ea00712a030beb90d9a03c6501d0d42d516b62a4 usb: add helper to extract bits 12:11 of wMaxPacketSize commit 541b6fe63023f3059cf85d47ff2767a3e42a8e44 upstream. 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 [bwh: Backported to 3.2: adjust filename, context] Signed-off-by: Ben Hutchings --- diff --git a/include/linux/usb/ch9.h b/include/linux/usb/ch9.h index 046b1f4382df..68a3b10d8e0b 100644 --- a/include/linux/usb/ch9.h +++ b/include/linux/usb/ch9.h @@ -390,6 +390,11 @@ 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) + #define USB_ENDPOINT_SYNCTYPE 0x0c #define USB_ENDPOINT_SYNC_NONE (0 << 2) #define USB_ENDPOINT_SYNC_ASYNC (1 << 2) @@ -592,6 +597,20 @@ 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; +} + /*-------------------------------------------------------------------------*/ /* USB_DT_SS_ENDPOINT_COMP: SuperSpeed Endpoint Companion descriptor */