spi: spi-omap2-mcspi.c: Toggle CS after each word
authorMatthias Brugger <matthias.bgg@gmail.com>
Thu, 24 Jan 2013 12:40:41 +0000 (13:40 +0100)
committerMark Brown <broonie@opensource.wolfsonmicro.com>
Sat, 26 Jan 2013 09:00:04 +0000 (17:00 +0800)
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
include/linux/platform_data/spi-omap2-mcspi.h

index 31f6e842ea860063494e79db43770853094ccdc9..12789fcfa980d9057019ab074ba2a7f6a73062b5 100644 (file)
@@ -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;
index a65572d53211cf2dc51b97c7ca438c2020520862..c100456eab17958bbdbe6571e6346db864c87ead 100644 (file)
@@ -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