spi: spi-omap2-mcspi.c: Toggle CS after each word

This patch allows the board code to define SPI devices which needs to
toggle the chip select after every word send. This is needed to get a
better resolution reading e.g. an ADC data stream.
Apart from that, as in the normal code CS is controlled by software,
a transfer is done much faster.

Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/spi/spi-omap2-mcspi.c

@@ -927,6 +927,7 @@ static void omap2_mcspi_work(struct omap2_mcspi *mcspi, struct spi_message *m)
 
 	struct spi_device		*spi;
 	struct spi_transfer		*t = NULL;
+	struct spi_master		*master;
 	int				cs_active = 0;
 	struct omap2_mcspi_cs		*cs;
 	struct omap2_mcspi_device_config *cd;
@@ -935,6 +936,7 @@ static void omap2_mcspi_work(struct omap2_mcspi *mcspi, struct spi_message *m)
 	u32				chconf;
 
 	spi = m->spi;
+	master = spi->master;
 	cs = spi->controller_state;
 	cd = spi->controller_data;
 
@@ -952,6 +954,14 @@ static void omap2_mcspi_work(struct omap2_mcspi *mcspi, struct spi_message *m)
 			if (!t->speed_hz && !t->bits_per_word)
 				par_override = 0;
 		}
+		if (cd && cd->cs_per_word) {
+			chconf = mcspi->ctx.modulctrl;
+			chconf &= ~OMAP2_MCSPI_MODULCTRL_SINGLE;
+			mcspi_write_reg(master, OMAP2_MCSPI_MODULCTRL, chconf);
+			mcspi->ctx.modulctrl =
+				mcspi_read_cs_reg(spi, OMAP2_MCSPI_MODULCTRL);
+		}
+
 
 		if (!cs_active) {
 			omap2_mcspi_force_cs(spi, 1);
@@ -1013,6 +1023,14 @@ static void omap2_mcspi_work(struct omap2_mcspi *mcspi, struct spi_message *m)
 	if (cs_active)
 		omap2_mcspi_force_cs(spi, 0);
 
+	if (cd && cd->cs_per_word) {
+		chconf = mcspi->ctx.modulctrl;
+		chconf |= OMAP2_MCSPI_MODULCTRL_SINGLE;
+		mcspi_write_reg(master, OMAP2_MCSPI_MODULCTRL, chconf);
+		mcspi->ctx.modulctrl =
+			mcspi_read_cs_reg(spi, OMAP2_MCSPI_MODULCTRL);
+	}
+
 	omap2_mcspi_set_enable(spi, 0);
 
 	m->status = status;

include/linux/platform_data/spi-omap2-mcspi.h

@@ -22,6 +22,9 @@ struct omap2_mcspi_dev_attr {
 
 struct omap2_mcspi_device_config {
 	unsigned turbo_mode:1;
+
+	/* toggle chip select after every word */
+	unsigned cs_per_word:1;
 };
 
 #endif