spi/ep93xx: add DMA support

This patch adds DMA support for the EP93xx SPI driver. By default the DMA is
not enabled but it can be enabled by setting ep93xx_spi_info.use_dma to true
in board configuration file.

Note that the SPI driver still uses PIO for small transfers (<= 8 bytes) for
performance reasons.

Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/spi/ep93xx_spi b/Documentation/spi/ep93xx_spi
index 6325f5b48635..d8eb01c15db1 100644
--- a/Documentation/spi/ep93xx_spi
+++ b/Documentation/spi/ep93xx_spi
@@ -88,6 +88,16 @@ static void __init ts72xx_init_machine(void)
                             ARRAY_SIZE(ts72xx_spi_devices));
 }
 
+The driver can use DMA for the transfers also. In this case ts72xx_spi_info
+becomes:
+
+static struct ep93xx_spi_info ts72xx_spi_info = {
+        .num_chipselect = ARRAY_SIZE(ts72xx_spi_devices),
+        .use_dma        = true;
+};
+
+Note that CONFIG_EP93XX_DMA should be enabled as well.
+
 Thanks to
 =========
 Martin Guy, H. Hartley Sweeten and others who helped me during development of