serial: at91: add rx dma support

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Request a cyclic dma channel for rx dma use. Use cyclic transfer is to prevent
receive data overrun.

We allocate a cycle dma cookie after request channel,
after that, enable uart timeout interrupt in startup stage, when data successful
received, the timeout callback will check the residual bytes and insert
receiving datas into the framework during the transfer interval.

When current descriptor finished, the dma callback will also check the residual
bytes and filp the receiving data.

Signed-off-by: Elen Song <elen.song@atmel.com>
Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Elen Song 2013-07-22 16:30:27 +08:00 • committed by Greg Kroah-Hartman

parent 08f738be88

commit 34df42f59a

1 changed files with 220 additions and 4 deletions

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224

drivers/tty/serial/atmel_serial.c

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