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>

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 31f6e84..12789fc 100644 (file)
--- 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 (file)
--- 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