[v2] spi: spi-omap2-mcspi.c: Toggle CS after each word

Commit Message

Matthias Brugger Jan. 24, 2013, 12:40 p.m. UTC

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 <[e-mail]>
---
 drivers/spi/spi-omap2-mcspi.c                 | 18 ++++++++++++++++++
 include/linux/platform_data/spi-omap2-mcspi.h |  3 +++
 2 files changed, 21 insertions(+)

Comments

Mark Brown Jan. 26, 2013, 9 a.m. UTC | #1

On Thu, Jan 24, 2013 at 01:40:41PM +0100, Matthias Brugger wrote:
> 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.

Applied, thanks.

Patch

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 31f6e84..12789fc 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/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;
diff --git a/include/linux/platform_data/spi-omap2-mcspi.h b/include/linux/platform_data/spi-omap2-mcspi.h
index a65572d..c100456 100644
--- a/include/linux/platform_data/spi-omap2-mcspi.h
+++ b/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