spi: orion: add LSB support

The orion spi driver currently only supports the normal (i.e. MSB) mode.
This patch adds LSB first mode.

Also correct the comment about supported SPI modes that was left over by
b15d5d70 ("spi/orion: Add SPI_CHPA and SPI_CPOL support to kirkwood
driver.").
Signed-off-by: Bastian Stender <bst@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-orion.c

@@ -39,6 +39,8 @@
 
 #define ORION_SPI_IF_CTRL_REG		0x00
 #define ORION_SPI_IF_CONFIG_REG		0x04
+#define ORION_SPI_IF_RXLSBF		BIT(14)
+#define ORION_SPI_IF_TXLSBF		BIT(13)
 #define ORION_SPI_DATA_OUT_REG		0x08
 #define ORION_SPI_DATA_IN_REG		0x0c
 #define ORION_SPI_INT_CAUSE_REG		0x10
@@ -234,6 +236,11 @@ orion_spi_mode_set(struct spi_device *spi)
 		reg |= ORION_SPI_MODE_CPOL;
 	if (spi->mode & SPI_CPHA)
 		reg |= ORION_SPI_MODE_CPHA;
+	if (spi->mode & SPI_LSB_FIRST)
+		reg |= ORION_SPI_IF_RXLSBF | ORION_SPI_IF_TXLSBF;
+	else
+		reg &= ~(ORION_SPI_IF_RXLSBF | ORION_SPI_IF_TXLSBF);
+
 	writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 }
 
@@ -591,8 +598,8 @@ static int orion_spi_probe(struct platform_device *pdev)
 			master->bus_num = cell_index;
 	}
 
-	/* we support only mode 0, and no options */
-	master->mode_bits = SPI_CPHA | SPI_CPOL;
+	/* we support all 4 SPI modes and LSB first option */
+	master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST;
 	master->set_cs = orion_spi_set_cs;
 	master->transfer_one = orion_spi_transfer_one;
 	master->num_chipselect = ORION_NUM_CHIPSELECTS;