From: Linus Walleij linus.walleij@linaro.org
[ Upstream commit 7251953d784baf7e5416afabe030a0e81de1a938 ]
The Freescale MPC8xxx had a special quirk for handling a single hardwired chipselect, the case when we're using neither GPIO nor native chip select: when inspecting the device tree and finding zero "cs-gpios" on the device node the code would assume we have a single hardwired chipselect that leaves the device always selected.
This quirk is not handled by the new core code, so we need to check the "cs-gpios" explicitly in the driver and set pdata->max_chipselect = 1 which will later fall through to the SPI master ->num_chipselect.
Make sure not to assign the chip select handler in this case: there is no handling needed since the chip is always selected, and this is what the old code did as well.
Cc: Christophe Leroy christophe.leroy@c-s.fr Reported-by: Christophe Leroy christophe.leroy@c-s.fr Fixes: 0f0581b24bd0 ("spi: fsl: Convert to use CS GPIO descriptors") Signed-off-by: Linus Walleij linus.walleij@linaro.org Tested-by: Christophe Leroy christophe.leroy@c-s.fr (No tested the Link: https://lore.kernel.org/r/20191128083718.39177-3-linus.walleij@linaro.org Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/spi/spi-fsl-spi.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spi-fsl-spi.c b/drivers/spi/spi-fsl-spi.c index ad1abea6e8b0..be7c6ba73072 100644 --- a/drivers/spi/spi-fsl-spi.c +++ b/drivers/spi/spi-fsl-spi.c @@ -729,8 +729,18 @@ static int of_fsl_spi_probe(struct platform_device *ofdev) } } #endif - - pdata->cs_control = fsl_spi_cs_control; + /* + * Handle the case where we have one hardwired (always selected) + * device on the first "chipselect". Else we let the core code + * handle any GPIOs or native chip selects and assign the + * appropriate callback for dealing with the CS lines. This isn't + * supported on the GRLIB variant. + */ + ret = gpiod_count(dev, "cs"); + if (ret <= 0) + pdata->max_chipselect = 1; + else + pdata->cs_control = fsl_spi_cs_control; }
ret = of_address_to_resource(np, 0, &mem);