diff options
| author | Felipe Balbi <felipe.balbi@linux.intel.com> | 2016-09-26 10:51:18 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2018-02-13 18:32:23 +0000 |
| commit | ea00712a030beb90d9a03c6501d0d42d516b62a4 (patch) | |
| tree | e8d241e339df4a74e50b4352b0c8653bdf6c282f /include/linux | |
| parent | d6d76df2094546ddf21489197b1a6833b0c16e40 (diff) | |
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 <felipe.balbi@linux.intel.com>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/usb/ch9.h | 19 |
1 files changed, 19 insertions, 0 deletions
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 */ |