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

Richard Leitner
2018-10-16T09:28:21Z

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;
+
+ 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;
+ }
+
+ 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);
+ dev_err(dev, "unable to request GPIO reset pin (%d)\n", err);
+ return err;
+ }
+ dev_dbg(dev, "got GPIO reset pin\n");
+
+ return 0;
+}
+
+static const struct of_device_id sx8654_of_match[] = {
+ { .compatible = "semtech,sx8654", },
+ { },
+};
+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;
-
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