diff options
| author | Linus Walleij <linus.walleij@linaro.org> | 2019-12-05 10:13:40 +0100 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2019-12-09 18:46:34 +0000 |
| commit | 4a07b8bcd503c842bcf0171cdbccdfdac3d985c3 (patch) | |
| tree | aaa3ab1ae1173dfd6384024cda28fed155b0db5a /drivers/spi/spi-bitbang.c | |
| parent | 8a6553ecdf976d6a34664bd491f0ea74a15aa982 (diff) | |
spi: bitbang: Make chipselect callback optional
The ->chipselect() callback on the bit-banged SPI library
master is optional if using GPIO descriptors: when using
descriptors exclusively without any native chipselects,
the core does not even call out the the native ->set_cs()
and therefore ->chipselect() on a bit-banged SPI master
will not even be called in this case.
Make sure to respect the SPI_MASTER_GPIO_SS as used by
e.g. spi-gpio.c though: this setting will make the core
handle the chip select using GPIO descriptors *AND* call
the local chipselect handler.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20191205091340.59850-1-linus.walleij@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi/spi-bitbang.c')
| -rw-r--r-- | drivers/spi/spi-bitbang.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c index d84e22dd6f9f..68491a8bf7b5 100644 --- a/drivers/spi/spi-bitbang.c +++ b/drivers/spi/spi-bitbang.c @@ -329,8 +329,20 @@ static void spi_bitbang_set_cs(struct spi_device *spi, bool enable) int spi_bitbang_init(struct spi_bitbang *bitbang) { struct spi_master *master = bitbang->master; + bool custom_cs; - if (!master || !bitbang->chipselect) + if (!master) + return -EINVAL; + /* + * We only need the chipselect callback if we are actually using it. + * If we just use GPIO descriptors, it is surplus. If the + * SPI_MASTER_GPIO_SS flag is set, we always need to call the + * driver-specific chipselect routine. + */ + custom_cs = (!master->use_gpio_descriptors || + (master->flags & SPI_MASTER_GPIO_SS)); + + if (custom_cs && !bitbang->chipselect) return -EINVAL; mutex_init(&bitbang->lock); @@ -344,7 +356,12 @@ int spi_bitbang_init(struct spi_bitbang *bitbang) master->prepare_transfer_hardware = spi_bitbang_prepare_hardware; master->unprepare_transfer_hardware = spi_bitbang_unprepare_hardware; master->transfer_one = spi_bitbang_transfer_one; - master->set_cs = spi_bitbang_set_cs; + /* + * When using GPIO descriptors, the ->set_cs() callback doesn't even + * get called unless SPI_MASTER_GPIO_SS is set. + */ + if (custom_cs) + master->set_cs = spi_bitbang_set_cs; if (!bitbang->txrx_bufs) { bitbang->use_dma = 0; |