From 9a87d22369cda8b273c60537ded33e75f24b3dc0 Mon Sep 17 00:00:00 2001
From: Jason Zhang <jason.zhang@rock-chips.com>
Date: Wed, 15 Jun 2022 14:34:00 +0800
Subject: [PATCH] iio: light: vl6180: support power control using gpio

There are AVDD and GPIO0/CE in the pinout of STMicro VL6180:
  - AVDD (Digital/analog power supply 2.6 to 3.0 V),
  - GPIO0/CE (Power-up default is chip enable (CE)).

These two pins are gpio connected in some reference design boards and
control the power in the Power-up timing constraints. This patch
emulates this situation.

Signed-off-by: Jason Zhang <jason.zhang@rock-chips.com>
Change-Id: I610455ea7ca738303ec6dd6ff496576ff2e716ce
---
 drivers/iio/light/vl6180.c | 42 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/iio/light/vl6180.c b/drivers/iio/light/vl6180.c
index 4775bd785e50..1d68f2fceecf 100644
--- a/drivers/iio/light/vl6180.c
+++ b/drivers/iio/light/vl6180.c
@@ -26,6 +26,8 @@
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
 
 #define VL6180_DRV_NAME "vl6180"
 
@@ -87,6 +89,8 @@ struct vl6180_data {
 	struct mutex lock;
 	unsigned int als_gain_milli;
 	unsigned int als_it_ms;
+	struct gpio_desc *avdd;
+	struct gpio_desc *chip_enable;
 };
 
 enum { VL6180_ALS, VL6180_RANGE, VL6180_PROX };
@@ -439,11 +443,40 @@ static const struct iio_info vl6180_info = {
 	.attrs = &vl6180_attribute_group,
 };
 
+static int vl6180_power_enable(struct vl6180_data *data)
+{
+	/* Enable power supply. */
+	if (!IS_ERR_OR_NULL(data->avdd))
+		gpiod_set_value_cansleep(data->avdd, 1);
+
+	/* Power-up default is chip enable (CE). */
+	if (!IS_ERR_OR_NULL(data->chip_enable)) {
+		gpiod_set_value_cansleep(data->chip_enable, 0);
+		usleep_range(500, 1000);
+		gpiod_set_value_cansleep(data->chip_enable, 1);
+	}
+
+	return 0;
+}
+
 static int vl6180_init(struct vl6180_data *data)
 {
 	struct i2c_client *client = data->client;
 	int ret;
 
+	ret = vl6180_power_enable(data);
+	if (ret) {
+		dev_err(&client->dev, "failed to configure power\n");
+		return ret;
+	}
+
+	/*
+	 * After the MCU boot sequence the device enters software standby,
+	 * host initialization can commence immediately after entering
+	 * software standby.
+	 */
+	usleep_range(500, 1000);
+
 	ret = vl6180_read_byte(client, VL6180_MODEL_ID);
 	if (ret < 0)
 		return ret;
@@ -515,6 +548,15 @@ static int vl6180_probe(struct i2c_client *client,
 	indio_dev->name = VL6180_DRV_NAME;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 
+	/*
+	 * NOTE: If the power is controlled by gpio, the power
+	 * configuration should match the power-up timing.
+	 */
+	data->avdd = devm_gpiod_get_optional(&client->dev, "avdd",
+					     GPIOD_OUT_HIGH);
+	data->chip_enable = devm_gpiod_get_optional(&client->dev, "chip-enable",
+						    GPIOD_OUT_HIGH);
+
 	ret = vl6180_init(data);
 	if (ret < 0)
 		return ret;