Re: [PATCH v3 2/2] HID: i2c-hid: support regulator power on/off

[Dmitry Torokhov]

On Thu, Dec 01, 2016 at 04:31:10PM -0800, Brian Norris wrote:
> On some boards, we need to enable a regulator before using the HID, and
> it's also nice to save power in suspend by disabling it. Support an
> optional "vdd-supply" and a companion initialization delay.
> 
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
> Signed-off-by: Caesar Wang <wxt@xxxxxxxxxxxxxx>
> Cc: Jiri Kosina <jikos@xxxxxxxxxx>
> Cc: linux-input@xxxxxxxxxxxxxxx
> ---
> v2:
>  * support compatible property for wacom, with specific "vdd-supply" name
>  * support the 100ms delay needed for this digitizer
>  * target regulator support only at specific device
> 
> v3:
>  * drop Wacom specifics and allow this to be used generically
>  * add "init-delay-ms" property support
> 
>  drivers/hid/i2c-hid/i2c-hid.c | 48 ++++++++++++++++++++++++++++++++++++++++++-
>  include/linux/i2c/i2c-hid.h   |  6 ++++++
>  2 files changed, 53 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index b3ec4f2de875..4cb523133d13 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -37,7 +37,9 @@
>  #include <linux/mutex.h>
>  #include <linux/acpi.h>
>  #include <linux/of.h>
> +#include <linux/of_device.h>
>  #include <linux/gpio/consumer.h>
> +#include <linux/regulator/consumer.h>
>  
>  #include <linux/i2c/i2c-hid.h>
>  
> @@ -937,6 +939,22 @@ static int i2c_hid_of_probe(struct i2c_client *client,
>  	}
>  	pdata->hid_descriptor_address = val;
>  
> +	ret = of_property_read_u32(dev->of_node, "init-delay-ms", &val);
> +	if (!ret)
> +		pdata->init_delay_ms = ret;
> +
> +	pdata->supply = devm_regulator_get_optional(dev, "vdd");

Make it devm_regulator_get(), it's cleaner (you'll get a dummy regulator
that you can enable/disbale and not check if it is null or not).

	pdata->supply = devm_regulator_get_optional(dev, "vdd");
	if (IS_ERR(pdata->supply)) {
		ret = PTR_ERR(pdata->supply);
		if (ret != -EPROBE_DEFER)
			dev_err(...);
		return ret;
	}

Thanks.

> +	if (IS_ERR(pdata->supply)) {
> +		ret = PTR_ERR(pdata->supply);
> +		pdata->supply = NULL;
> +		if (ret == -EPROBE_DEFER)
> +			return ret;
> +		if (ret == -ENODEV)
> +			return 0;
> +		dev_err(dev, "Failed to get regulator: %d\n", ret);
> +		return ret;
> +	}
> +
>  	return 0;
>  }
>  
> @@ -983,6 +1001,17 @@ static int i2c_hid_probe(struct i2c_client *client,
>  		ihid->pdata = *platform_data;
>  	}
>  
> +	if (ihid->pdata.supply) {
> +		ret = regulator_enable(ihid->pdata.supply);
> +		if (ret < 0) {
> +			dev_err(&client->dev, "Failed to enable regulator: %d\n",
> +				ret);
> +			return ret;
> +		}
> +		if (ihid->pdata.init_delay_ms)
> +			msleep(ihid->pdata.init_delay_ms);
> +	}
> +
>  	if (client->irq > 0) {
>  		ihid->irq = client->irq;
>  	} else if (ACPI_COMPANION(&client->dev)) {
> @@ -1100,6 +1129,9 @@ static int i2c_hid_remove(struct i2c_client *client)
>  	if (ihid->desc)
>  		gpiod_put(ihid->desc);
>  
> +	if (ihid->pdata.supply)
> +		regulator_disable(ihid->pdata.supply);
> +
>  	kfree(ihid);
>  
>  	acpi_dev_remove_driver_gpios(ACPI_COMPANION(&client->dev));
> @@ -1152,6 +1184,11 @@ static int i2c_hid_suspend(struct device *dev)
>  		else
>  			hid_warn(hid, "Failed to enable irq wake: %d\n",
>  				wake_status);
> +	} else if (ihid->pdata.supply) {
> +		ret = regulator_disable(ihid->pdata.supply);
> +		if (ret < 0)
> +			hid_warn(hid, "Failed to disable supply: %d\n",
> +				 ret);
>  	}
>  
>  	return 0;
> @@ -1165,7 +1202,16 @@ static int i2c_hid_resume(struct device *dev)
>  	struct hid_device *hid = ihid->hid;
>  	int wake_status;
>  
> -	if (device_may_wakeup(&client->dev) && ihid->irq_wake_enabled) {
> +	if (!device_may_wakeup(&client->dev)) {
> +		if (ihid->pdata.supply) {
> +			ret = regulator_enable(ihid->pdata.supply);
> +			if (ret < 0)
> +				hid_warn(hid, "Failed to enable supply: %d\n",
> +					 ret);
> +			if (ihid->pdata.init_delay_ms)
> +				msleep(ihid->pdata.init_delay_ms);
> +		}
> +	} else if (ihid->irq_wake_enabled) {
>  		wake_status = disable_irq_wake(ihid->irq);
>  		if (!wake_status)
>  			ihid->irq_wake_enabled = false;
> diff --git a/include/linux/i2c/i2c-hid.h b/include/linux/i2c/i2c-hid.h
> index 7aa901d92058..97688cde4a91 100644
> --- a/include/linux/i2c/i2c-hid.h
> +++ b/include/linux/i2c/i2c-hid.h
> @@ -14,9 +14,13 @@
>  
>  #include <linux/types.h>
>  
> +struct regulator;
> +
>  /**
>   * struct i2chid_platform_data - used by hid over i2c implementation.
>   * @hid_descriptor_address: i2c register where the HID descriptor is stored.
> + * @supply: regulator for powering on the device.
> + * @init_delay_ms: delay after powering on before device is usable.
>   *
>   * Note that it is the responsibility of the platform driver (or the acpi 5.0
>   * driver, or the flattened device tree) to setup the irq related to the gpio in
> @@ -31,6 +35,8 @@
>   */
>  struct i2c_hid_platform_data {
>  	u16 hid_descriptor_address;
> +	struct regulator *supply;
> +	int init_delay_ms;
>  };
>  
>  #endif /* __LINUX_I2C_HID_H */
> -- 
> 2.8.0.rc3.226.g39d4020
> 

-- 
Dmitry