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Commit a30a555d authored by Martin Sperl's avatar Martin Sperl Committed by Mark Brown
Browse files

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: e3a2be30)

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: default avatarMartin Sperl <kernel@martin.sperl.org>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent e3a2be30

drivers/spi/spi-bcm2835.c

+44 −5
Original line number Diff line number Diff line
@@ -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 */

	/* 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,

		"setup: only three native chip-selects are supported\n");

	return -EINVAL;

			"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)