[PATCH v2 6/9] Input: cap11xx - add reset gpio support

[Jun Yan <jerrysteve1101@gmail.com>]

Some CAP11xx devices (CAP1126/CAP1188) have a dedicated RESET pin.
Add hardware reset operation to improve device reliability and
ensure proper initialization on probe.

Signed-off-by: Jun Yan <jerrysteve1101@gmail.com>
---
 drivers/input/keyboard/cap11xx.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/input/keyboard/cap11xx.c b/drivers/input/keyboard/cap11xx.c
index 686174722204..75746a8a2233 100644
--- a/drivers/input/keyboard/cap11xx.c
+++ b/drivers/input/keyboard/cap11xx.c
@@ -5,6 +5,7 @@
  * (c) 2014 Daniel Mack <linux@zonque.org>
  */
 
+#include <linux/delay.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
@@ -43,6 +44,9 @@
 
 #define CAP11XX_MANUFACTURER_ID	0x5d
 
+#define CAP11XX_T_RST_FILT_MIN_US	10000
+#define CAP11XX_T_RST_ON_MIN_MS	400
+
 #ifdef CONFIG_LEDS_CLASS
 struct cap11xx_led {
 	struct cap11xx_priv *priv;
@@ -55,6 +59,7 @@ struct cap11xx_priv {
 	struct regmap *regmap;
 	struct device *dev;
 	struct input_dev *idev;
+	struct gpio_desc *reset_gpio;
 	const struct cap11xx_hw_model *model;
 
 	struct cap11xx_led *leds;
@@ -452,6 +457,17 @@ static int cap11xx_i2c_probe(struct i2c_client *i2c_client)
 	if (IS_ERR(priv->regmap))
 		return PTR_ERR(priv->regmap);
 
+	priv->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(priv->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(priv->reset_gpio),
+				     "Failed to get 'reset' GPIO\n");
+	if (priv->reset_gpio) {
+		gpiod_set_value_cansleep(priv->reset_gpio, 1);
+		usleep_range(CAP11XX_T_RST_FILT_MIN_US, CAP11XX_T_RST_FILT_MIN_US * 2);
+		gpiod_set_value_cansleep(priv->reset_gpio, 0);
+		msleep(CAP11XX_T_RST_ON_MIN_MS);
+	}
+
 	error = regmap_read(priv->regmap, CAP11XX_REG_PRODUCT_ID, &val);
 	if (error)
 		return dev_err_probe(dev, error, "Failed to read product ID\n");
-- 
2.54.0