Re: [PATCH v3 1/3] hwmon: (pmbus) Use driver specific ops if they exist

[Guenter Roeck <linux@roeck-us.net>]

On Wed, Apr 27, 2022 at 03:02:11PM +0200, Mårten Lindahl wrote:
> Pmbus drivers using the default pmbus_regulator_ops for the enable/
> disable/is_enabled functions will use the standard pmbus core functions
> pmbus_read/write_byte_data. This could potentially influence some
> specific regulator chips that for example need a time delay before each
> data access.
> 
> Lets add support for drivers to use chip specific read/write operations
> when using the standard pmbus_regulator_ops.

The subject is misleading. It should be something like "introduce and
use write_byte_data callback". Also, existing code calling
pmbus_write_byte_data() should call _pmbus_write_byte_data() instead.
This applies to pmbus_update_fan() and pmbus_get_boolean().

Thanks,
Guenter

> 
> Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
> ---
>  drivers/hwmon/pmbus/pmbus.h      |  2 ++
>  drivers/hwmon/pmbus/pmbus_core.c | 58 +++++++++++++++++++++-----------
>  2 files changed, 40 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
> index e74b6ef070f3..c031a9700ace 100644
> --- a/drivers/hwmon/pmbus/pmbus.h
> +++ b/drivers/hwmon/pmbus/pmbus.h
> @@ -438,6 +438,8 @@ struct pmbus_driver_info {
>  	int (*read_byte_data)(struct i2c_client *client, int page, int reg);
>  	int (*read_word_data)(struct i2c_client *client, int page, int phase,
>  			      int reg);
> +	int (*write_byte_data)(struct i2c_client *client, int page, int reg,
> +			      u8 byte);
>  	int (*write_word_data)(struct i2c_client *client, int page, int reg,
>  			       u16 word);
>  	int (*write_byte)(struct i2c_client *client, int page, u8 value);
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index b2618b1d529e..1b0728c3c7d8 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -384,25 +384,6 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg, u8 value)
>  }
>  EXPORT_SYMBOL_NS_GPL(pmbus_write_byte_data, PMBUS);
>  
> -int pmbus_update_byte_data(struct i2c_client *client, int page, u8 reg,
> -			   u8 mask, u8 value)
> -{
> -	unsigned int tmp;
> -	int rv;
> -
> -	rv = pmbus_read_byte_data(client, page, reg);
> -	if (rv < 0)
> -		return rv;
> -
> -	tmp = (rv & ~mask) | (value & mask);
> -
> -	if (tmp != rv)
> -		rv = pmbus_write_byte_data(client, page, reg, tmp);
> -
> -	return rv;
> -}
> -EXPORT_SYMBOL_NS_GPL(pmbus_update_byte_data, PMBUS);
> -
>  /*
>   * _pmbus_read_byte_data() is similar to pmbus_read_byte_data(), but checks if
>   * a device specific mapping function exists and calls it if necessary.
> @@ -421,6 +402,43 @@ static int _pmbus_read_byte_data(struct i2c_client *client, int page, int reg)
>  	return pmbus_read_byte_data(client, page, reg);
>  }
>  
> +/*
> + * _pmbus_write_byte_data() is similar to pmbus_write_byte_data(), but checks if
> + * a device specific mapping function exists and calls it if necessary.
> + */
> +static int _pmbus_write_byte_data(struct i2c_client *client, int page, int reg, u8 value)
> +{
> +	struct pmbus_data *data = i2c_get_clientdata(client);
> +	const struct pmbus_driver_info *info = data->info;
> +	int status;
> +
> +	if (info->write_byte_data) {
> +		status = info->write_byte_data(client, page, reg, value);
> +		if (status != -ENODATA)
> +			return status;
> +	}
> +	return pmbus_write_byte_data(client, page, reg, value);
> +}
> +
> +int pmbus_update_byte_data(struct i2c_client *client, int page, u8 reg,
> +			   u8 mask, u8 value)
> +{
> +	unsigned int tmp;
> +	int rv;
> +
> +	rv = _pmbus_read_byte_data(client, page, reg);
> +	if (rv < 0)
> +		return rv;
> +
> +	tmp = (rv & ~mask) | (value & mask);
> +
> +	if (tmp != rv)
> +		rv = _pmbus_write_byte_data(client, page, reg, tmp);
> +
> +	return rv;
> +}
> +EXPORT_SYMBOL_NS_GPL(pmbus_update_byte_data, PMBUS);
> +
>  static struct pmbus_sensor *pmbus_find_sensor(struct pmbus_data *data, int page,
>  					      int reg)
>  {
> @@ -2396,7 +2414,7 @@ static int pmbus_regulator_is_enabled(struct regulator_dev *rdev)
>  	int ret;
>  
>  	mutex_lock(&data->update_lock);
> -	ret = pmbus_read_byte_data(client, page, PMBUS_OPERATION);
> +	ret = _pmbus_read_byte_data(client, page, PMBUS_OPERATION);
>  	mutex_unlock(&data->update_lock);
>  
>  	if (ret < 0)