[PATCH] spi: orion: Handle GPIO chip-selects

From: Chris Packham
Date: Mon May 22 2017 - 20:45:46 EST


Some hardware designs use GPIOs to add (or supplement) the SPI
chip-select so that more than one SPI slave device can be used.

For this to work with the spi-orion driver the SPI_MASTER_GPIO_SS flag
needs to be set (because the other outputs are gated internally by the
CS) and the correct chip-select (in this case CS0) needs to be driven by
the controller.

Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
---
drivers/spi/spi-orion.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-orion.c b/drivers/spi/spi-orion.c
index be2e87ee8b31..28fc9f161b9d 100644
--- a/drivers/spi/spi-orion.c
+++ b/drivers/spi/spi-orion.c
@@ -22,6 +22,7 @@
#include <linux/of_device.h>
#include <linux/clk.h>
#include <linux/sizes.h>
+#include <linux/gpio.h>
#include <asm/unaligned.h>

#define DRIVER_NAME "orion_spi"
@@ -320,12 +321,18 @@ orion_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
static void orion_spi_set_cs(struct spi_device *spi, bool enable)
{
struct orion_spi *orion_spi;
+ int cs;
+
+ if (gpio_is_valid(spi->cs_gpio))
+ cs = 0;
+ else
+ cs = spi->chip_select;

orion_spi = spi_master_get_devdata(spi->master);

orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, ORION_SPI_CS_MASK);
orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG,
- ORION_SPI_CS(spi->chip_select));
+ ORION_SPI_CS(cs));

/* Chip select logic is inverted from spi_set_cs */
if (!enable)
@@ -606,6 +613,7 @@ static int orion_spi_probe(struct platform_device *pdev)
master->setup = orion_spi_setup;
master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
master->auto_runtime_pm = true;
+ master->flags = SPI_MASTER_GPIO_SS;

platform_set_drvdata(pdev, master);

--
2.11.0.24.ge6920cf