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

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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>
This commit is contained in:
Matthias Brugger 2013-01-24 13:40:41 +01:00 committed by Mark Brown
parent 18dd6199fa
commit 5cbc7ca987
2 changed files with 21 additions and 0 deletions
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18
drivers/spi/spi-omap2-mcspi.c
View 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;

3
include/linux/platform_data/spi-omap2-mcspi.h
View 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