Re: [PATCH 2/7] Input: sx8654 - add reset-gpio support

Dmitry Torokhov
2018-10-16T17:39:39Z

Hi Richard,

On Tue, Oct 16, 2018 at 11:16:48AM +0200, Richard Leitner wrote:
> The sx8654 features a NRST input which may be connected to a GPIO.
> Therefore add support for hard-resetting the sx8654 via this NRST.
>
> If the reset-gpio property is provided the sx8654 is resetted via NRST
> instead of the soft-reset via I2C.
>
> Signed-off-by: Richard Leitner <richard.leitner@skidata.com>
> ---
> drivers/input/touchscreen/sx8654.c | 88 ++++++++++++++++++++++++++++++++------
> 1 file changed, 74 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/input/touchscreen/sx8654.c b/drivers/input/touchscreen/sx8654.c
> index ed29db3ec731..059127490c8d 100644
> --- a/drivers/input/touchscreen/sx8654.c
> +++ b/drivers/input/touchscreen/sx8654.c
> @@ -33,6 +33,8 @@
> #include <linux/i2c.h>
> #include <linux/interrupt.h>
> #include <linux/irq.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/delay.h>
>
> /* register addresses */
> #define I2C_REG_TOUCH0 0x00
> @@ -74,6 +76,7 @@
> struct sx8654 {
> struct input_dev *input;
> struct i2c_client *client;
> + struct gpio_desc *gpio_reset;
> };
>
> static irqreturn_t sx8654_irq(int irq, void *handle)
> @@ -124,6 +127,27 @@ static irqreturn_t sx8654_irq(int irq, void *handle)
> return IRQ_HANDLED;
> }
>
> +static int sx8654_reset(struct sx8654 *ts)
> +{
> + int err;
> +
> + if (ts->gpio_reset) {
> + gpiod_set_value_cansleep(ts->gpio_reset, 1);
> + udelay(2); /* Tpulse > 1µs */
> + gpiod_set_value_cansleep(ts->gpio_reset, 0);
> +
> + return 0;
> + }
> +
> + dev_dbg(&ts->client->dev, "NRST unavailable, try softreset\n");
> + err = i2c_smbus_write_byte_data(ts->client, I2C_REG_SOFTRESET,
> + SOFTRESET_VALUE);
> + if (err)
> + return err;

Have this in an "else" branch?

> +
> + return 0;
> +}
> +
> static int sx8654_open(struct input_dev *dev)
> {
> struct sx8654 *sx8654 = input_get_drvdata(dev);
> @@ -171,6 +195,44 @@ static void sx8654_close(struct input_dev *dev)
> }
> }
>
> +#ifdef CONFIG_OF
> +static int sx8654_get_ofdata(struct sx8654 *ts)
> +{
> + struct device *dev = &ts->client->dev;
> + struct device_node *node = dev->of_node;
> + int err;
> +
> + if (!node) {
> + ts->gpio_reset = NULL;
> + return 0;
> + }

There is no need to wrap this into CONFIG_OF or test "node". Just use
devm_gpiod_get_optional() and it will work equally well on DT, ACPI, and
static board systems.

> +
> + ts->gpio_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> + if (PTR_ERR(ts->gpio_reset) == -EPROBE_DEFER) {
> + return -EPROBE_DEFER;
> + } else if (IS_ERR(ts->gpio_reset)) {
> + err = PTR_ERR(ts->gpio_reset);

I'd do:

if (err != -EPROBE_DEFER)
dev_err(...)

here instead of separate branch.

> + dev_err(dev, "unable to request GPIO reset pin (%d)\n", err);
> + return err;
> + }
> + dev_dbg(dev, "got GPIO reset pin\n");

Also, I'd move all this code directly into probe() since all this
#ifdefery is not needed.

> +
> + return 0;
> +}
> +
> +static const struct of_device_id sx8654_of_match[] = {
> + { .compatible = "semtech,sx8654", },
> + { },
> +};

Please keep the device table wehere it was.

> +MODULE_DEVICE_TABLE(of, sx8654_of_match);
> +#else /* CONFIG_OF */
> +static int sx8654_get_ofdata(struct sx8654 *ts)
> +{
> + ts->gpio_reset = NULL;
> + return 0;
> +}
> +#endif /* CONFIG_OF */
> +
> static int sx8654_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> @@ -186,10 +248,20 @@ static int sx8654_probe(struct i2c_client *client,
> if (!sx8654)
> return -ENOMEM;
>
> + sx8654->client = client;
> +
> + error = sx8654_get_ofdata(sx8654);
> + if (error) {
> + dev_err(&client->dev, "get_ofdata failed: %d\n", error);
> + return error;
> + }
> +
> input = devm_input_allocate_device(&client->dev);
> if (!input)
> return -ENOMEM;
>
> + sx8654->input = input;
> +
> input->name = "SX8654 I2C Touchscreen";
> input->id.bustype = BUS_I2C;
> input->dev.parent = &client->dev;
> @@ -201,15 +273,11 @@ static int sx8654_probe(struct i2c_client *client,
> input_set_abs_params(input, ABS_X, 0, MAX_12BIT, 0, 0);
> input_set_abs_params(input, ABS_Y, 0, MAX_12BIT, 0, 0);
>
> - sx8654->client = client;
> - sx8654->input = input;
> -

Why do we need to move this?

> input_set_drvdata(sx8654->input, sx8654);
>
> - error = i2c_smbus_write_byte_data(client, I2C_REG_SOFTRESET,
> - SOFTRESET_VALUE);
> + error = sx8654_reset(sx8654);
> if (error) {
> - dev_err(&client->dev, "writing softreset value failed");
> + dev_err(&client->dev, "reset failed");
> return error;
> }
>
> @@ -256,14 +324,6 @@ static int sx8654_probe(struct i2c_client *client,
> return 0;
> }
>
> -#ifdef CONFIG_OF
> -static const struct of_device_id sx8654_of_match[] = {
> - { .compatible = "semtech,sx8654", },
> - { },
> -};
> -MODULE_DEVICE_TABLE(of, sx8654_of_match);
> -#endif
> -
> static const struct i2c_device_id sx8654_id_table[] = {
> { "semtech_sx8654", 0 },
> { },
> --
> 2.11.0
>

Thanks.

--
Dmitry