of/spi: Support specifying chip select as active high via device tree

The patch allows to specify that an SPI device needs an active high chip
select.

Signed-off-by: Wolfgang Ocker <weo@reccoware.de>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt
index de4063c..02ea9a9 100644 (file)
--- a/Documentation/powerpc/booting-without-of.txt
+++ b/Documentation/powerpc/booting-without-of.txt
@@ -1917,6 +1917,8 @@ platforms are moved over to use the flattened-device-tree model.
                        inverse clock polarity (CPOL) mode
     - spi-cpha        - (optional) Empty property indicating device requires
                        shifted clock phase (CPHA) mode
+    - spi-cs-high     - (optional) Empty property indicating device requires
+                       chip select active high
 
     SPI example for an MPC5200 SPI bus:
                spi@f00 {

diff --git a/drivers/of/of_spi.c b/drivers/of/of_spi.c
index b01eec0..bed0ed6 100644 (file)
--- a/drivers/of/of_spi.c
+++ b/drivers/of/of_spi.c
@@ -61,6 +61,8 @@ void of_register_spi_devices(struct spi_master *master, struct device_node *np)
                        spi->mode |= SPI_CPHA;
                if (of_find_property(nc, "spi-cpol", NULL))
                        spi->mode |= SPI_CPOL;
+               if (of_find_property(nc, "spi-cs-high", NULL))
+                       spi->mode |= SPI_CS_HIGH;
 
                /* Device speed */
                prop = of_get_property(nc, "spi-max-frequency", &len);