linux-kernel - Re: [PATCH v2 2/4] hwmon: (max6639) Add regulator support

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Message-ID: <20220118161108.GA4115171@roeck-us.net>
Date:   Tue, 18 Jan 2022 08:11:08 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Marcello Sylvester Bauer <sylv@...v.io>
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        Jean Delvare <jdelvare@...e.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH v2 2/4] hwmon: (max6639) Add regulator support

On Mon, Jan 17, 2022 at 11:40:24AM +0100, Marcello Sylvester Bauer wrote:
> Add regulator support for boards where the fan-supply have to be
> powered up before it can be used.
> 
> Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
> Signed-off-by: Marcello Sylvester Bauer <sylv@...v.io>
> ---
>  drivers/hwmon/max6639.c | 64 +++++++++++++++++++++++++++++++++++------
>  1 file changed, 56 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/hwmon/max6639.c b/drivers/hwmon/max6639.c
> index ccc0f047bd44..0b241f029229 100644
> --- a/drivers/hwmon/max6639.c
> +++ b/drivers/hwmon/max6639.c
> @@ -87,6 +87,9 @@ struct max6639_data {
>  	/* Register values initialized only once */
>  	u8 ppr;			/* Pulses per rotation 0..3 for 1..4 ppr */
>  	u8 rpm_range;		/* Index in above rpm_ranges table */
> +
> +	/* Optional regulator for FAN supply */
> +	struct regulator *reg;
>  };
>  
>  static struct max6639_data *max6639_update_device(struct device *dev)
> @@ -516,6 +519,11 @@ static int max6639_detect(struct i2c_client *client,
>  	return 0;
>  }
>  
> +static void max6639_regulator_disable(void *data)
> +{
> +	regulator_disable(data);
> +}
> +
>  static int max6639_probe(struct i2c_client *client)
>  {
>  	struct device *dev = &client->dev;
> @@ -528,6 +536,30 @@ static int max6639_probe(struct i2c_client *client)
>  		return -ENOMEM;
>  
>  	data->client = client;
> +
> +	data->reg = devm_regulator_get_optional(dev, "fan");
> +	if (IS_ERR(data->reg)) {
> +		if (PTR_ERR(data->reg) != -ENODEV) {
> +			err = (int)PTR_ERR(data->reg);
> +			dev_warn(dev, "Failed looking up fan supply: %d\n", err);

This could be -EPROBE_DEFER. I do not think that warrants
an error message.

> +			return err;
> +		}
> +		data->reg = NULL;
> +	} else {
> +		/* Spin up fans */
> +		err = regulator_enable(data->reg);
> +		if (err) {
> +			dev_err(dev, "Failed to enable fan supply: %d\n", err);
> +			return err;
> +		}
> +		err = devm_add_action_or_reset(dev, max6639_regulator_disable,
> +					       data->reg);
> +		if (err) {
> +			dev_err(dev, "Failed to register action: %d\n", err);
> +			return err;
> +		}
> +	}
> +
>  	mutex_init(&data->update_lock);
>  
>  	/* Initialize the max6639 chip */
> @@ -545,23 +577,39 @@ static int max6639_probe(struct i2c_client *client)
>  static int max6639_suspend(struct device *dev)
>  {
>  	struct i2c_client *client = to_i2c_client(dev);
> -	int data = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
> -	if (data < 0)
> -		return data;
> +	struct max6639_data *data = dev_get_drvdata(dev);
> +	int ret = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	if (data->reg)
> +		regulator_disable(data->reg);
>  
>  	return i2c_smbus_write_byte_data(client,
> -			MAX6639_REG_GCONFIG, data | MAX6639_GCONFIG_STANDBY);
> +			MAX6639_REG_GCONFIG, ret | MAX6639_GCONFIG_STANDBY);
>  }
>  
>  static int max6639_resume(struct device *dev)
>  {
>  	struct i2c_client *client = to_i2c_client(dev);
> -	int data = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
> -	if (data < 0)
> -		return data;
> +	struct max6639_data *data = dev_get_drvdata(dev);
> +	int ret;
> +
> +	if (data->reg) {
> +		ret = regulator_enable(data->reg);
> +		if (ret) {
> +			dev_err(dev, "Failed to enable fan supply: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	ret = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
> +	if (ret < 0)
> +		return ret;
>  
>  	return i2c_smbus_write_byte_data(client,
> -			MAX6639_REG_GCONFIG, data & ~MAX6639_GCONFIG_STANDBY);
> +			MAX6639_REG_GCONFIG, ret & ~MAX6639_GCONFIG_STANDBY);
>  }
>  #endif /* CONFIG_PM_SLEEP */
>