diff options
| author | Martin Sperl <kernel@martin.sperl.org> | 2015-04-06 17:16:31 +0000 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2015-04-10 19:50:52 +0100 |
| commit | a30a555d7435a440fab06fe5960cf3448d8cedd3 (patch) | |
| tree | 119afa8a1ede43f405397e2227e5ce4c69686f1b /drivers/spi/spi-bcm2835.c | |
| parent | e3a2be3030e2fec27a2577d3c52203da090a4366 (diff) | |
spi: bcm2835: transform native-cs to gpio-cs on first spi_setup
Transforms the bcm-2835 native SPI-chip select to their gpio-cs equivalent.
This allows for some support of some optimizations that are not
possible due to HW-gliches on the CS line - especially filling
the FIFO before enabling SPI interrupts (by writing to CS register)
while the transfer is already in progress (See commit: e3a2be3030e2)
This patch also works arround some issues in bcm2835-pinctrl which does not
set the value when setting the GPIO as output - it just sets up output and
(typically) leaves the GPIO as low. When a fix for this is merged then this
gpio_set_value can get removed from bcm2835_spi_setup.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi/spi-bcm2835.c')
| -rw-r--r-- | drivers/spi/spi-bcm2835.c | 49 |
1 files changed, 44 insertions, 5 deletions
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index 08e5406c5029..90064494e828 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -291,8 +291,15 @@ static void bcm2835_spi_set_cs(struct spi_device *spi, bool gpio_level) bcm2835_wr(bs, BCM2835_SPI_CS, cs); } +static int chip_match_name(struct gpio_chip *chip, void *data) +{ + return !strcmp(chip->label, data); +} + static int bcm2835_spi_setup(struct spi_device *spi) { + int err; + struct gpio_chip *chip; /* * sanity checking the native-chipselects */ @@ -300,13 +307,45 @@ static int bcm2835_spi_setup(struct spi_device *spi) return 0; if (gpio_is_valid(spi->cs_gpio)) return 0; - if (spi->chip_select < 3) + if (spi->chip_select > 1) { + /* error in the case of native CS requested with CS > 1 + * officially there is a CS2, but it is not documented + * which GPIO is connected with that... + */ + dev_err(&spi->dev, + "setup: only two native chip-selects are supported\n"); + return -EINVAL; + } + /* now translate native cs to GPIO */ + + /* get the gpio chip for the base */ + chip = gpiochip_find("pinctrl-bcm2835", chip_match_name); + if (!chip) return 0; - /* error in the case of native CS requested with CS-id > 2 */ - dev_err(&spi->dev, - "setup: only three native chip-selects are supported\n"); - return -EINVAL; + /* and calculate the real CS */ + spi->cs_gpio = chip->base + 8 - spi->chip_select; + + /* and set up the "mode" and level */ + dev_info(&spi->dev, "setting up native-CS%i as GPIO %i\n", + spi->chip_select, spi->cs_gpio); + + /* set up GPIO as output and pull to the correct level */ + err = gpio_direction_output(spi->cs_gpio, + (spi->mode & SPI_CS_HIGH) ? 0 : 1); + if (err) { + dev_err(&spi->dev, + "could not set CS%i gpio %i as output: %i", + spi->chip_select, spi->cs_gpio, err); + return err; + } + /* the implementation of pinctrl-bcm2835 currently does not + * set the GPIO value when using gpio_direction_output + * so we are setting it here explicitly + */ + gpio_set_value(spi->cs_gpio, (spi->mode & SPI_CS_HIGH) ? 0 : 1); + + return 0; } static int bcm2835_spi_probe(struct platform_device *pdev) |