usb: gadget: r8a66597-udc: Make BUSWAIT configurable through platform data

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BUSWAIT is a 4-bit-wide value that controls the number of access waits
from the CPU to on-chip USB module. b'0000 inserts 0 wait (2 access
cycles) and b'1111 inserts 15 waits (17 access cycles, hardware
initial value), respectively.

BUSWAIT value depends on peripheral clock frequency supplied to on-chip
of each CPU, hence should be configurable through platform data.

Note that this patch assumes that b'0000 (0 wait, 2 access cycles) is
rerely used and considered as invalid. If valid 'buswait' data is not
provided by platform, initial b'1111 (15 waits, 17 access cycles) will
be applied as a safe default.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

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This commit is contained in:

Yoshihiro Shimoda 2011-07-08 14:51:27 +09:00 • committed by Felipe Balbi

parent deafeb24e8

commit 5154e9f126

2 changed files with 8 additions and 1 deletions

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6

drivers/usb/gadget/r8a66597-udc.c

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3

include/linux/usb/r8a66597.h

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