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authorGreg Ungerer <gerg@linux-m68k.org>2017-07-11 14:22:11 +1000
committerMark Brown <broonie@kernel.org>2017-08-29 21:09:03 +0100
commit602c8f4485cd1e6de67e41c78db96fa4f6808e53 (patch)
tree48520f23a5e8ca55000619767f47ad5870cb99f3 /drivers/spi
parent5904c9d3c9bd52f79718d1806175271b4bd20718 (diff)
spi: imx: fix use of native chip-selects with devicetree
The commonly used mechanism of specifying the hardware or native chip-select on an SPI device in devicetree (that is "cs-gpios = <0>") does not result in the native chip-select being configured for use. So external SPI devices that require use of the native chip-select will not work. You can successfully specify native chip-selects if using a platform setup by specifying the cs-gpio as negative offset by 32. And that works correctly. You cannot use the same method in devicetree. The logic in the spi-imx.c driver during probe uses core spi function of_spi_register_master() in spi.c to parse the "cs-gpios" devicetree tag. For valid GPIO values that will be recorded for use, all other entries in the cs_gpios list will be set to -ENOENT. So entries like "<0>" will be set to -ENOENT in the cs_gpios list. When the SPI device registers are setup the code will use the GPIO listed in the cs_gpios list for the desired chip-select. If the cs_gpio is less then 0 then it is intended to be for a native chip-select, and its cs_gpio value is added to 32 to get the chipselect number to use. Problem is that with devicetree this can only ever be -ENOENT (which is -2), and that alone results in an invalid chip-select number. But also doesn't allow selection of the native chip-select at all. To fix, if the cs_gpio specified for this spi device is not a valid GPIO then use the "chip_select" (that is the native chip-select number) for hardware setup. Signed-off-by: Greg Ungerer <gerg@linux-m68k.org> Reviewed-by: Vladimir Zapolskiy <vz@mleia.com> Tested-by: Vladimir Zapolskiy <vz@mleia.com> Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/spi-imx.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 6fcb6adf9565..babb15f07995 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -622,8 +622,8 @@ static int mx31_config(struct spi_device *spi)
reg |= MX31_CSPICTRL_POL;
if (spi->mode & SPI_CS_HIGH)
reg |= MX31_CSPICTRL_SSPOL;
- if (spi->cs_gpio < 0)
- reg |= (spi->cs_gpio + 32) <<
+ if (!gpio_is_valid(spi->cs_gpio))
+ reg |= (spi->chip_select) <<
(is_imx35_cspi(spi_imx) ? MX35_CSPICTRL_CS_SHIFT :
MX31_CSPICTRL_CS_SHIFT);
@@ -714,8 +714,8 @@ static int mx21_config(struct spi_device *spi)
reg |= MX21_CSPICTRL_POL;
if (spi->mode & SPI_CS_HIGH)
reg |= MX21_CSPICTRL_SSPOL;
- if (spi->cs_gpio < 0)
- reg |= (spi->cs_gpio + 32) << MX21_CSPICTRL_CS_SHIFT;
+ if (!gpio_is_valid(spi->cs_gpio))
+ reg |= spi->chip_select << MX21_CSPICTRL_CS_SHIFT;
writel(reg, spi_imx->base + MXC_CSPICTRL);