spi: add new SPI_CS_WORD flag

commit 0baf9eb25572eea0cf48249c1d152d8373956a7c upstream

This adds a new SPI mode flag, SPI_CS_WORD, that is used to indicate
that a SPI device requires the chip select to be toggled after each
word that is transferred.
Signed-off-by: NDavid Lechner <david@lechnology.com>
Signed-off-by: NMark Brown <broonie@kernel.org>
Signed-off-by: NZou Cao <zoucao@linux.alibaba.com>
Reviewed-by: NBaoyou Xie <xie.baoyou@linux.alibaba.com>

include/linux/spi/spi.h

@@ -163,6 +163,7 @@ struct spi_device {
 #define	SPI_TX_QUAD	0x200			/* transmit with 4 wires */
 #define	SPI_RX_DUAL	0x400			/* receive with 2 wires */
 #define	SPI_RX_QUAD	0x800			/* receive with 4 wires */
+#define SPI_CS_WORD	0x1000			/* toggle cs after each word */
 	int			irq;
 	void			*controller_state;
 	void			*controller_data;
@@ -177,7 +178,6 @@ struct spi_device {
 	 * the controller talks to each chip, like:
 	 *  - memory packing (12 bit samples into low bits, others zeroed)
 	 *  - priority
-	 *  - drop chipselect after each word
 	 *  - chipselect delays
 	 *  - ...
 	 */