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authorChip Coldwell <coldwell@redhat.com>2008-02-08 04:21:06 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 09:22:37 -0800
commita66706158d6bc4d9eb29c37852001f78f4c8989c (patch)
treed2d593dc2902c1db1ea6d0ef417dc3426e0b3bae /drivers/serial/Kconfig
parent1ecc26bd2789ddb253f61e182a61c776663fe44c (diff)
atmel_serial: add DMA support
This patch is based on the DMA-patch by Chip Coldwell for the AT91/AT32 serial USARTS, with some tweaks to make it apply neatly on top of the other patches in this series. The RX and TX code has been moved to a tasklet and reworked a bit. Instead of depending on the ENDRX and TIMEOUT bits in CSR, we simply grab as much data as we can from the DMA buffers. I think this closes a race where the ENDRX bit is set after we read CSR but before we read RPR, although I haven't confirmed this. Similarly, the two TX handlers (ENDTX and TXBUFE) have been combined into one. Since the current code only uses a single TX buffer, there's no point in handling those interrupts separately. This also fixes a DMA sync bug in the original patch. [linux@bohmer.net: rebased onto irq-splitup patch] [hskinnemoen@atmel.com: moved to tasklet, fixed dma bug, misc cleanups] [hskinnemoen@atmel.com: atmel_serial dma: Misc fixes and cleanups] Signed-off-by: Remy Bohmer <linux@bohmer.net> Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Andrew Victor <linux@maxim.org.za> Tested-by: Marc Pignat <marc.pignat@hevs.ch> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/serial/Kconfig')
-rw-r--r--drivers/serial/Kconfig15
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 84a054d7e98..b82595cf13e 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -380,6 +380,21 @@ config SERIAL_ATMEL_CONSOLE
console is the device which receives all kernel messages and
warnings and which allows logins in single user mode).
+config SERIAL_ATMEL_PDC
+ bool "Support DMA transfers on AT91 / AT32 serial port"
+ depends on SERIAL_ATMEL
+ default y
+ help
+ Say Y here if you wish to use the PDC to do DMA transfers to
+ and from the Atmel AT91 / AT32 serial port. In order to
+ actually use DMA transfers, make sure that the use_dma_tx
+ and use_dma_rx members in the atmel_uart_data struct is set
+ appropriately for each port.
+
+ Note that break and error handling currently doesn't work
+ properly when DMA is enabled. Make sure that ports where
+ this matters don't use DMA.
+
config SERIAL_ATMEL_TTYAT
bool "Install as device ttyATn instead of ttySn"
depends on SERIAL_ATMEL=y