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

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Date:   Wed, 19 Jan 2022 10:42:49 +0100
From:   sylv <sylv@...v.io>
To:     Guenter Roeck <linux@...ck-us.net>
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 Tue, 2022-01-18 at 08:11 -0800, Guenter Roeck wrote:
> 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.

I see. I'll adapt it analog to: drivers/hwmon/pwm-fan.c:323

> 
> > +			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 */
> >