To 74hc595 and 74lv595, there is an OE(low active) input pin. To some boards, this pin is controller by GPIO, so handling this pin in driver. When driver probe, use GPIOD_OUT_LOW flag when requesting the gpio, so OE is set to low when probe.
Signed-off-by: Peng Fan <[email protected]> Cc: Linus Walleij <[email protected]> --- drivers/gpio/gpio-74x164.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c index a6607fa..e44422c 100644 --- a/drivers/gpio/gpio-74x164.c +++ b/drivers/gpio/gpio-74x164.c @@ -23,6 +23,7 @@ struct gen_74x164_chip { struct gpio_chip gpio_chip; struct mutex lock; u32 registers; + struct gpio_desc *enable_gpio; /* * Since the registers are chained, every byte sent will make * the previous byte shift to the next register in the @@ -142,6 +143,12 @@ static int gen_74x164_probe(struct spi_device *spi) chip->gpio_chip.parent = &spi->dev; chip->gpio_chip.owner = THIS_MODULE; + chip->enable_gpio = devm_gpiod_get(&spi->dev, "enable", GPIOD_OUT_LOW); + if (IS_ERR(chip->enable_gpio)) { + dev_dbg(&spi->dev, "No enable-gpios property\n"); + chip->enable_gpio = NULL; + } + mutex_init(&chip->lock); ret = __gen_74x164_write_config(chip); @@ -164,6 +171,8 @@ static int gen_74x164_remove(struct spi_device *spi) { struct gen_74x164_chip *chip = spi_get_drvdata(spi); + if (chip->enable_gpio) + gpiod_set_value(chip->enable_gpio, 0); gpiochip_remove(&chip->gpio_chip); mutex_destroy(&chip->lock); -- 2.6.6
