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authorThor Thayer <tthayer@opensource.altera.com>2016-10-10 09:25:24 -0500
committerMark Brown <broonie@kernel.org>2016-10-11 12:29:04 +0200
commit6b1576aa875347c6454d911a2e001138c2cec7d5 (patch)
treeab2efceebe210623e9f54e967cec554dfa32bfb3 /drivers/spi/spi.c
parent2ce04684335f886fb5adb9ecbd2a85affca549d1 (diff)
downloadlinux-next-6b1576aa875347c6454d911a2e001138c2cec7d5.tar.gz
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>
Diffstat (limited to 'drivers/spi/spi.c')
-rw-r--r--drivers/spi/spi.c9
1 files changed, 7 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