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gpio: 74x164: Introduce 'enable-gpios' property 

74HC595 has an /OE (output enable) pin that can be controlled by a GPIO.

Introduce an optional property called 'enable-gpios' that allows
controlling the /OE pin.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Fabio Estevam 2017-08-07 09:41:50 -03:00 committed by Linus Walleij
parent ee949b51e4
commit 7ebc194d0f
2 changed files with 13 additions and 0 deletions
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3
Documentation/devicetree/bindings/gpio/gpio-74x164.txt
View File

@ -12,6 +12,9 @@ Required properties:
1 = active low
- registers-number: Number of daisy-chained shift registers
Optional properties:
- enable-gpios: GPIO connected to the OE (Output Enable) pin.
Example:
gpio5: gpio5@0 {

10
drivers/gpio/gpio-74x164.c
View File

@ -9,6 +9,7 @@
* published by the Free Software Foundation.
*/
#include <linux/gpio/consumer.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/spi/spi.h>
@ -31,6 +32,7 @@ struct gen_74x164_chip {
* numbering, store the bytes in reverse order.
*/
u8 buffer[0];
struct gpio_desc *gpiod_oe;
};
static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
@ -126,6 +128,13 @@ static int gen_74x164_probe(struct spi_device *spi)
if (!chip)
return -ENOMEM;
chip->gpiod_oe = devm_gpiod_get_optional(&spi->dev, "enable",
GPIOD_OUT_LOW);
if (IS_ERR(chip->gpiod_oe))
return PTR_ERR(chip->gpiod_oe);
gpiod_set_value_cansleep(chip->gpiod_oe, 1);
spi_set_drvdata(spi, chip);
chip->gpio_chip.label = spi->modalias;
@ -164,6 +173,7 @@ static int gen_74x164_remove(struct spi_device *spi)
{
struct gen_74x164_chip *chip = spi_get_drvdata(spi);
gpiod_set_value_cansleep(chip->gpiod_oe, 0);
gpiochip_remove(&chip->gpio_chip);
mutex_destroy(&chip->lock);