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| author | Martin Sperl <kernel@martin.sperl.org> | 2019-03-30 10:31:03 +0100 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2019-04-03 06:31:51 +0200 |
| commit | 519f2c22a6c71a9fefed1166c36d48246e010514 (patch) | |
| tree | a681f03e67d1f5ba920815588a84f829aa0ed083 /drivers/spi/spi-bcm2835aux.c | |
| parent | spi: bcm2835aux: fix driver to not allow 65535 (=-1) cs-gpios (diff) | |
| download | linux-519f2c22a6c71a9fefed1166c36d48246e010514.tar.xz linux-519f2c22a6c71a9fefed1166c36d48246e010514.zip | |
spi: bcm2835aux: warn in dmesg that native cs is not really supported
From personal bad experience (even as the author of the original driver)
it shows that native-cs is "somewhat" supported by the spi bus driver
when using a buggy device tree.
So make sure that the driver is warning in dmesg about this fact
that we are running in a not supported mode that may have surprizing
limitations.
Fixes: 1ea29b39f4c812ec ("spi: bcm2835aux: add bcm2835 auxiliary spi device...")
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi/spi-bcm2835aux.c')
| -rw-r--r-- | drivers/spi/spi-bcm2835aux.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c index c8acde017b6a..a105db371417 100644 --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -396,6 +396,38 @@ static void bcm2835aux_spi_handle_err(struct spi_master *master, bcm2835aux_spi_reset_hw(bs); } +static int bcm2835aux_spi_setup(struct spi_device *spi) +{ + int ret; + + /* sanity check for native cs */ + if (spi->mode & SPI_NO_CS) + return 0; + if (gpio_is_valid(spi->cs_gpio)) + return 0; + + /* for dt-backwards compatibility: only support native on CS0 + * known things not supported with broken native CS: + * * multiple chip-selects: cs0-cs2 are all + * simultaniously asserted whenever there is a transfer + * this even includes SPI_NO_CS + * * SPI_CS_HIGH: cs are always asserted low + * * cs_change: cs is deasserted after each spi_transfer + * * cs_delay_usec: cs is always deasserted one SCK cycle + * after the last transfer + * probably more... + */ + dev_warn(&spi->dev, + "Native CS is not supported - please configure cs-gpio in device-tree\n"); + + if (spi->chip_select == 0) + return 0; + + dev_warn(&spi->dev, "Native CS is not working for cs > 0\n"); + + return -EINVAL; +} + static int bcm2835aux_spi_probe(struct platform_device *pdev) { struct spi_master *master; @@ -425,6 +457,7 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev) * a spi_transfer */ master->num_chipselect = 1; + master->setup = bcm2835aux_spi_setup; master->transfer_one = bcm2835aux_spi_transfer_one; master->handle_err = bcm2835aux_spi_handle_err; master->prepare_message = bcm2835aux_spi_prepare_message; |