Hi,
On Thu, 29 Dec 2016 14:27:25 -0800 Steve Longerbeam wrote:
> Add optional reset-gpios pin control. If present, de-assert the
> specified reset gpio pin to bring the chip out of reset.
>
> Signed-off-by: Steve Longerbeam <steve_longerbeam@xxxxxxxxxx>
> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
> Cc: Alexandre Courbot <gnurou@xxxxxxxxx>
> Cc: linux-gpio@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
>
> ---
>
> v2:
> - documented optional reset-gpios property in
> Documentation/devicetree/bindings/gpio/gpio-pca953x.txt.
> ---
> Documentation/devicetree/bindings/gpio/gpio-pca953x.txt | 4 ++++
> drivers/gpio/gpio-pca953x.c | 17 +++++++++++++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt b/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
> index 08dd15f..da54f4c 100644
> --- a/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
> +++ b/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
> @@ -29,6 +29,10 @@ Required properties:
> onsemi,pca9654
> exar,xra1202
>
> +Optional properties:
> + - reset-gpios: GPIO specification for the RESET input
> +
> +
> Example:
>
>
> diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
> index d5d72d8..d1c0bd5 100644
> --- a/drivers/gpio/gpio-pca953x.c
> +++ b/drivers/gpio/gpio-pca953x.c
> @@ -22,6 +22,7 @@
> #include <linux/of_platform.h>
> #include <linux/acpi.h>
> #include <linux/regulator/consumer.h>
> +#include <linux/gpio/consumer.h>
>
> #define PCA953X_INPUT 0
> #define PCA953X_OUTPUT 1
> @@ -133,6 +134,7 @@ struct pca953x_chip {
> const char *const *names;
> unsigned long driver_data;
> struct regulator *regulator;
> + struct gpio_desc *reset_gpio;
>
> const struct pca953x_reg_config *regs;
>
> @@ -756,6 +758,21 @@ static int pca953x_probe(struct i2c_client *client,
> } else {
> chip->gpio_start = -1;
> irq_base = 0;
> +
> + /* see if we need to de-assert a reset pin */
> + chip->reset_gpio = devm_gpiod_get_optional(&client->dev,
> + "reset",
> + GPIOD_OUT_LOW);
> + if (IS_ERR(chip->reset_gpio)) {
> + dev_err(&client->dev, "request for reset pin failed\n");
> + return PTR_ERR(chip->reset_gpio);
> + }
> +
> + if (chip->reset_gpio) {
> + /* bring chip out of reset */
> + dev_info(&client->dev, "releasing reset\n");
> + gpiod_set_value(chip->reset_gpio, 0);
>
The pin is already initialized to the inactive state thru the
GPIOD_OUT_LOW flag in devm_gpiod_get_optional(), so this call to
gpiod_set_value() is useless.
Lothar Waßmann
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