s3cmci: Kconfig selection for PIO/DMA/Both

Add a selection for the data transfer mode of the s3cmci driver, allowing
for either a configuration or rumtime selection of the use of the DMA or
PIO transfer code.

The PIO only mode is 476 bytes smaller than the driver with both methods
compiled in.

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 7cb057f3f883..cf6a6545240b 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -276,6 +276,40 @@ config MMC_S3C
 
 	  If unsure, say N.
 
+choice
+	prompt "Samsung S3C SD/MMC transfer code"
+	depends on MMC_S3C
+
+config MMC_S3C_PIO
+	bool "Use PIO transfers only"
+	help
+	  Use PIO to transfer data between memory and the hardware.
+
+	  PIO is slower than DMA as it requires CPU instructions to
+	  move the data. This has been the traditional default for
+	  the S3C MCI driver.
+
+config MMC_S3C_DMA
+	bool "Use DMA transfers only (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+	help
+	  Use DMA to transfer data between memory and the hardare.
+
+	  Currently, the DMA support in this driver seems to not be
+	  working properly and needs to be debugged before this
+	  option is useful.
+
+config MMC_S3C_PIODMA
+	bool "Support for both PIO and DMA (EXPERIMENTAL)"
+	help
+	  Compile both the PIO and DMA transfer routines into the
+	  driver and let the platform select at run-time which one
+	  is best.
+
+	  See notes for the DMA option.
+
+endchoice
+
 config MMC_SDRICOH_CS
 	tristate "MMC/SD driver for Ricoh Bay1Controllers (EXPERIMENTAL)"
 	depends on EXPERIMENTAL && PCI && PCMCIA