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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: e3a2be3030
)
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>
This commit is contained in:
parent
e3a2be3030
commit
a30a555d74
@ -291,8 +291,15 @@ static void bcm2835_spi_set_cs(struct spi_device *spi, bool gpio_level)
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bcm2835_wr(bs, BCM2835_SPI_CS, cs);
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}
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static int chip_match_name(struct gpio_chip *chip, void *data)
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{
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return !strcmp(chip->label, data);
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}
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static int bcm2835_spi_setup(struct spi_device *spi)
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{
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int err;
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struct gpio_chip *chip;
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/*
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* sanity checking the native-chipselects
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*/
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@ -300,13 +307,45 @@ static int bcm2835_spi_setup(struct spi_device *spi)
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return 0;
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if (gpio_is_valid(spi->cs_gpio))
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return 0;
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if (spi->chip_select < 3)
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if (spi->chip_select > 1) {
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/* error in the case of native CS requested with CS > 1
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* officially there is a CS2, but it is not documented
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* which GPIO is connected with that...
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*/
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dev_err(&spi->dev,
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"setup: only two native chip-selects are supported\n");
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return -EINVAL;
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}
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/* now translate native cs to GPIO */
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/* get the gpio chip for the base */
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chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
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if (!chip)
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return 0;
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/* error in the case of native CS requested with CS-id > 2 */
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/* and calculate the real CS */
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spi->cs_gpio = chip->base + 8 - spi->chip_select;
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/* and set up the "mode" and level */
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dev_info(&spi->dev, "setting up native-CS%i as GPIO %i\n",
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spi->chip_select, spi->cs_gpio);
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/* set up GPIO as output and pull to the correct level */
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err = gpio_direction_output(spi->cs_gpio,
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(spi->mode & SPI_CS_HIGH) ? 0 : 1);
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if (err) {
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dev_err(&spi->dev,
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"setup: only three native chip-selects are supported\n");
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return -EINVAL;
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"could not set CS%i gpio %i as output: %i",
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spi->chip_select, spi->cs_gpio, err);
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return err;
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}
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/* the implementation of pinctrl-bcm2835 currently does not
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* set the GPIO value when using gpio_direction_output
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* so we are setting it here explicitly
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*/
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gpio_set_value(spi->cs_gpio, (spi->mode & SPI_CS_HIGH) ? 0 : 1);
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return 0;
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}
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static int bcm2835_spi_probe(struct platform_device *pdev)
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