diff options
| author | Thor Thayer <tthayer@opensource.altera.com> | 2016-10-10 17:25:24 +0300 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2016-10-11 13:29:04 +0300 |
| commit | 6b1576aa875347c6454d911a2e001138c2cec7d5 (patch) | |
| tree | ab2efceebe210623e9f54e967cec554dfa32bfb3 | |
| parent | 2ce04684335f886fb5adb9ecbd2a85affca549d1 (diff) | |
| download | linux-6b1576aa875347c6454d911a2e001138c2cec7d5.tar.xz | |
spi: Add Flag to Enable Slave Select with GPIO Chip Select.
Some SPI masters require slave selection before the transfer
can begin [1]. The SPI framework currently selects the chip using
either 1) the internal CS mechanism or 2) the GPIO CS, but not both.
This patch adds a new master->flags define to indicate both the GPIO
CS and the internal chip select mechanism should be used.
Tested On:
Altera CycloneV development kit
Compile tested for build errors on x86_64 (allyesconfigs)
[1] DesignWare dw_apb_ssi Databook, Version 3.20a (page 39)
Signed-off-by: Thor Thayer <tthayer@opensource.altera.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
| -rw-r--r-- | drivers/spi/spi.c | 9 | ||||
| -rw-r--r-- | include/linux/spi/spi.h | 1 |
2 files changed, 8 insertions, 2 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 8146ccd35a1a..8708da7c8140 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -697,10 +697,15 @@ static void spi_set_cs(struct spi_device *spi, bool enable) if (spi->mode & SPI_CS_HIGH) enable = !enable; - if (gpio_is_valid(spi->cs_gpio)) + if (gpio_is_valid(spi->cs_gpio)) { gpio_set_value(spi->cs_gpio, !enable); - else if (spi->master->set_cs) + /* Some SPI masters need both GPIO CS & slave_select */ + if ((spi->master->flags & SPI_MASTER_GPIO_SS) && + spi->master->set_cs) + spi->master->set_cs(spi, !enable); + } else if (spi->master->set_cs) { spi->master->set_cs(spi, !enable); + } } #ifdef CONFIG_HAS_DMA diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 4b743ac35396..75c6bd0ac605 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -442,6 +442,7 @@ struct spi_master { #define SPI_MASTER_NO_TX BIT(2) /* can't do buffer write */ #define SPI_MASTER_MUST_RX BIT(3) /* requires rx */ #define SPI_MASTER_MUST_TX BIT(4) /* requires tx */ +#define SPI_MASTER_GPIO_SS BIT(5) /* GPIO CS must select slave */ /* * on some hardware transfer / message size may be constrained |