[PATCH v2 2/8] Input: sx8654 - add reset-gpio support

Richard Leitner
2018-10-17T16:07:57Z

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 | 40 +++++++++++++++++++++++++++++++++++---
1 file changed, 37 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/sx8654.c b/drivers/input/touchscreen/sx8654.c
index ed29db3ec731..238f56b1581b 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;
+ else
+ return 0;
+}
+
static int sx8654_open(struct input_dev *dev)
{
struct sx8654 *sx8654 = input_get_drvdata(dev);
@@ -186,6 +210,17 @@ static int sx8654_probe(struct i2c_client *client,
if (!sx8654)
return -ENOMEM;

+ sx8654->gpio_reset = devm_gpiod_get_optional(&client->dev, "reset",
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(sx8654->gpio_reset)) {
+ error = PTR_ERR(sx8654->gpio_reset);
+ if (error != -EPROBE_DEFER)
+ dev_err(&client->dev, "unable to get reset-gpio: %d\n",
+ error);
+ return error;
+ }
+ dev_dbg(&client->dev, "got GPIO reset pin\n");
+
input = devm_input_allocate_device(&client->dev);
if (!input)
return -ENOMEM;
@@ -206,10 +241,9 @@ static int sx8654_probe(struct i2c_client *client,

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;
}

--
2.11.0