spi: add "spi-lsb-first" to devicetree

add optional property devicetree for SPI slave nodes
into devicetree so that LSB mode can be enabled by devicetree.

Signed-off-by: Zhao Qiang <B45475@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/spi/spi-bus.txt

@@ -55,6 +55,8 @@ contain the following properties.
     		chip select active high
 - spi-3wire       - (optional) Empty property indicating device requires
     		    3-wire mode.
+- spi-lsb-first   - (optional) Empty property indicating device requires
+		LSB first mode.
 - spi-tx-bus-width - (optional) The bus width(number of data wires) that
                       used for MOSI. Defaults to 1 if not present.
 - spi-rx-bus-width - (optional) The bus width(number of data wires) that

drivers/spi/spi.c

@@ -1234,6 +1234,8 @@ static void of_register_spi_devices(struct spi_master *master)
 			spi->mode |= SPI_CS_HIGH;
 		if (of_find_property(nc, "spi-3wire", NULL))
 			spi->mode |= SPI_3WIRE;
+		if (of_find_property(nc, "spi-lsb-first", NULL))
+			spi->mode |= SPI_LSB_FIRST;
 
 		/* Device DUAL/QUAD mode */
 		if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {