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authorMartin Sperl <kernel@martin.sperl.org>2015-04-06 17:16:31 +0000
committerpopcornmix <popcornmix@gmail.com>2015-05-18 14:12:30 +0100
commitfbe7fdd9c98e82bb4ed3c4ca6c19da13d64a40a6 (patch)
treec912d98a832a12ef0437360bb9d44c33d0913bfa /drivers
parent33c8b51d5e9038bfe577106fab47323f29679d20 (diff)
downloadlinux-fbe7fdd9c98e82bb4ed3c4ca6c19da13d64a40a6.tar.gz
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')
-rw-r--r--drivers/spi/spi-bcm2835.c49
1 files changed, 44 insertions, 5 deletions
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 321dbe27173b..033b93fcb0de 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)