[PATCH v2 1/9] media: ov2740: Add support for reset GPIO

[Hans de Goede <hdegoede@redhat.com>]

On some ACPI platforms, such as Chromebooks the ACPI methods to
change the power-state (_PS0 and _PS3) fully take care of powering
on/off the sensor.

On other ACPI platforms, such as e.g. various ThinkPad models with
IPU6 + ov2740 sensor, the sensor driver must control the reset GPIO
and the sensor's clock itself.

Add support for having the driver control an optional reset GPIO.

Reviewed-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/media/i2c/ov2740.c | 48 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/drivers/media/i2c/ov2740.c b/drivers/media/i2c/ov2740.c
index 24e468485fbf..e5f9569a229d 100644
--- a/drivers/media/i2c/ov2740.c
+++ b/drivers/media/i2c/ov2740.c
@@ -4,6 +4,7 @@
 #include <asm/unaligned.h>
 #include <linux/acpi.h>
 #include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
@@ -333,6 +334,9 @@ struct ov2740 {
 	struct v4l2_ctrl *hblank;
 	struct v4l2_ctrl *exposure;
 
+	/* GPIOs, clocks */
+	struct gpio_desc *reset_gpio;
+
 	/* Current mode */
 	const struct ov2740_mode *cur_mode;
 
@@ -1058,6 +1062,26 @@ static int ov2740_register_nvmem(struct i2c_client *client,
 	return 0;
 }
 
+static int ov2740_suspend(struct device *dev)
+{
+	struct v4l2_subdev *sd = dev_get_drvdata(dev);
+	struct ov2740 *ov2740 = to_ov2740(sd);
+
+	gpiod_set_value_cansleep(ov2740->reset_gpio, 1);
+	return 0;
+}
+
+static int ov2740_resume(struct device *dev)
+{
+	struct v4l2_subdev *sd = dev_get_drvdata(dev);
+	struct ov2740 *ov2740 = to_ov2740(sd);
+
+	gpiod_set_value_cansleep(ov2740->reset_gpio, 0);
+	msleep(20);
+
+	return 0;
+}
+
 static int ov2740_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
@@ -1073,12 +1097,24 @@ static int ov2740_probe(struct i2c_client *client)
 	if (!ov2740)
 		return -ENOMEM;
 
+	ov2740->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(ov2740->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(ov2740->reset_gpio),
+				     "failed to get reset GPIO\n");
+
 	v4l2_i2c_subdev_init(&ov2740->sd, client, &ov2740_subdev_ops);
 	full_power = acpi_dev_state_d0(&client->dev);
 	if (full_power) {
-		ret = ov2740_identify_module(ov2740);
+		/* ACPI does not always clear the reset GPIO / enable the clock */
+		ret = ov2740_resume(dev);
 		if (ret)
-			return dev_err_probe(dev, ret, "failed to find sensor\n");
+			return dev_err_probe(dev, ret, "failed to power on sensor\n");
+
+		ret = ov2740_identify_module(ov2740);
+		if (ret) {
+			dev_err_probe(dev, ret, "failed to find sensor\n");
+			goto probe_error_power_off;
+		}
 	}
 
 	ov2740->cur_mode = &supported_modes[0];
@@ -1132,9 +1168,16 @@ static int ov2740_probe(struct i2c_client *client)
 probe_error_v4l2_ctrl_handler_free:
 	v4l2_ctrl_handler_free(ov2740->sd.ctrl_handler);
 
+probe_error_power_off:
+	if (full_power)
+		ov2740_suspend(dev);
+
 	return ret;
 }
 
+static DEFINE_RUNTIME_DEV_PM_OPS(ov2740_pm_ops, ov2740_suspend, ov2740_resume,
+				 NULL);
+
 static const struct acpi_device_id ov2740_acpi_ids[] = {
 	{"INT3474"},
 	{}
@@ -1146,6 +1189,7 @@ static struct i2c_driver ov2740_i2c_driver = {
 	.driver = {
 		.name = "ov2740",
 		.acpi_match_table = ov2740_acpi_ids,
+		.pm = pm_sleep_ptr(&ov2740_pm_ops),
 	},
 	.probe = ov2740_probe,
 	.remove = ov2740_remove,
-- 
2.41.0