media: ov2740: Add support for external clock

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 clock.

Reviewed-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

diff --git a/drivers/media/i2c/ov2740.c b/drivers/media/i2c/ov2740.c
index fef1b6f3f316b8338753fa6c3861cff465fc5580..653cd96bb1563481280d3229c4da910a21eab4fc 100644 (file)
--- a/drivers/media/i2c/ov2740.c
+++ b/drivers/media/i2c/ov2740.c
@@ -3,6 +3,7 @@
 
 #include <asm/unaligned.h>
 #include <linux/acpi.h>
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
@@ -336,6 +337,7 @@ struct ov2740 {
 
        /* GPIOs, clocks */
        struct gpio_desc *reset_gpio;
+       struct clk *clk;
 
        /* Current mode */
        const struct ov2740_mode *cur_mode;
@@ -1071,6 +1073,7 @@ static int ov2740_suspend(struct device *dev)
        struct ov2740 *ov2740 = to_ov2740(sd);
 
        gpiod_set_value_cansleep(ov2740->reset_gpio, 1);
+       clk_disable_unprepare(ov2740->clk);
        return 0;
 }
 
@@ -1078,6 +1081,11 @@ static int ov2740_resume(struct device *dev)
 {
        struct v4l2_subdev *sd = dev_get_drvdata(dev);
        struct ov2740 *ov2740 = to_ov2740(sd);
+       int ret;
+
+       ret = clk_prepare_enable(ov2740->clk);
+       if (ret)
+               return ret;
 
        gpiod_set_value_cansleep(ov2740->reset_gpio, 0);
        msleep(20);
@@ -1105,6 +1113,11 @@ static int ov2740_probe(struct i2c_client *client)
                return dev_err_probe(dev, PTR_ERR(ov2740->reset_gpio),
                                     "failed to get reset GPIO\n");
 
+       ov2740->clk = devm_clk_get_optional(dev, "clk");
+       if (IS_ERR(ov2740->clk))
+               return dev_err_probe(dev, PTR_ERR(ov2740->clk),
+                                    "failed to get clock\n");
+
        v4l2_i2c_subdev_init(&ov2740->sd, client, &ov2740_subdev_ops);
        ov2740->sd.internal_ops = &ov2740_internal_ops;
        full_power = acpi_dev_state_d0(&client->dev);