[PATCH v2 1/2] Input: atmel_mxt_ts: Add support for optional regulators.

["Paweł Chmiel" <pawel.mikolaj.chmiel@gmail.com>]

This patch adds optional regulators, which can be used to power
up touchscreen. After enabling regulators, we need to wait 150msec.
This value is taken from official driver.

It was tested on Samsung Galaxy i9000 (based on Samsung S5PV210 SOC).

Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
---
Changes from v1:
  - Enable regulators only if reset_gpio is present.
  - Switch from devm_regulator_get_optional to devm_regulator_get
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 46 ++++++++++++++++++++++++++++++--
 1 file changed, 44 insertions(+), 2 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 54fe190fd4bc..005f0fee9fc8 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -27,6 +27,7 @@
 #include <linux/interrupt.h>
 #include <linux/of.h>
 #include <linux/property.h>
+#include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 #include <linux/gpio/consumer.h>
 #include <linux/property.h>
@@ -194,10 +195,10 @@ enum t100_type {
 
 /* Delay times */
 #define MXT_BACKUP_TIME		50	/* msec */
-#define MXT_RESET_GPIO_TIME	20	/* msec */
 #define MXT_RESET_INVALID_CHG	100	/* msec */
 #define MXT_RESET_TIME		200	/* msec */
 #define MXT_RESET_TIMEOUT	3000	/* msec */
+#define MXT_REGULATOR_DELAY	150	/* msec */
 #define MXT_CRC_TIMEOUT		1000	/* msec */
 #define MXT_FW_RESET_TIME	3000	/* msec */
 #define MXT_FW_CHG_TIMEOUT	300	/* msec */
@@ -310,6 +311,8 @@ struct mxt_data {
 	struct t7_config t7_cfg;
 	struct mxt_dbg dbg;
 	struct gpio_desc *reset_gpio;
+	struct regulator *vdd_reg;
+	struct regulator *avdd_reg;
 
 	/* Cached parameters from object table */
 	u16 T5_address;
@@ -3076,6 +3079,22 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		return error;
 	}
 
+	data->vdd_reg = devm_regulator_get(&client->dev, "vdd");
+	if (IS_ERR(data->vdd_reg)) {
+		error = PTR_ERR(data->vdd_reg);
+		dev_err(&client->dev, "Failed to get vdd regulator: %d\n",
+			error);
+		return error;
+	}
+
+	data->avdd_reg = devm_regulator_get(&client->dev, "avdd");
+	if (IS_ERR(data->avdd_reg)) {
+		error = PTR_ERR(data->avdd_reg);
+		dev_err(&client->dev, "Failed to get avdd regulator: %d\n",
+			error);
+		return error;
+	}
+
 	error = devm_request_threaded_irq(&client->dev, client->irq,
 					  NULL, mxt_interrupt, IRQF_ONESHOT,
 					  client->name, data);
@@ -3087,7 +3106,26 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	disable_irq(client->irq);
 
 	if (data->reset_gpio) {
-		msleep(MXT_RESET_GPIO_TIME);
+		error = regulator_enable(data->vdd_reg);
+		if (error) {
+			dev_err(&client->dev, "Failed to enable vdd regulator: %d\n",
+				error);
+			return error;
+		}
+
+		error = regulator_enable(data->avdd_reg);
+		if (error) {
+			dev_err(&client->dev, "Failed to enable avdd regulator: %d\n",
+				error);
+			return error;
+		}
+
+		/*
+		 * According to maXTouch power sequencing specification, RESET line
+		 * must be kept low until some time after regulators come up to
+		 * voltage
+		 */
+		msleep(MXT_REGULATOR_DELAY);
 		gpiod_set_value(data->reset_gpio, 1);
 		msleep(MXT_RESET_INVALID_CHG);
 	}
@@ -3116,6 +3154,10 @@ static int mxt_remove(struct i2c_client *client)
 	struct mxt_data *data = i2c_get_clientdata(client);
 
 	disable_irq(data->irq);
+	if (data->reset_gpio) {
+		regulator_disable(data->avdd_reg);
+		regulator_disable(data->vdd_reg);
+	}
 	sysfs_remove_group(&client->dev.kobj, &mxt_attr_group);
 	mxt_free_input_device(data);
 	mxt_free_object_table(data);
-- 
2.7.4