Re: [PATCH v5 5/9] hwmon: (tmp421) really disable channels

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

On Thu, Oct 14, 2021 at 03:09:08PM +0200, Krzysztof Adamski wrote:
> Recent patch added possibility to disable selected channels. That would
> only make sure that the ENODATA is returned for those channels but would
> not configure the actual hardware.
> 
> With this patch, the config register is written to make sure the
> channels are disabled also at hardware level.
> 
> Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>

Applied, again after "s/^  / /"

Guenter

> ---
>  drivers/hwmon/tmp421.c | 44 ++++++++++++++++++++++++++++++++++++------
>  1 file changed, 38 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
> index 606914f20910..b402e81ae5d5 100644
> --- a/drivers/hwmon/tmp421.c
> +++ b/drivers/hwmon/tmp421.c
> @@ -33,6 +33,9 @@ enum chips { tmp421, tmp422, tmp423, tmp441, tmp442 };
>  /* The TMP421 registers */
>  #define TMP421_STATUS_REG			0x08
>  #define TMP421_CONFIG_REG_1			0x09
> +#define TMP421_CONFIG_REG_2			0x0A
> +#define TMP421_CONFIG_REG_REN(x)		(BIT(3 + (x)))
> +#define TMP421_CONFIG_REG_REN_MASK		GENMASK(6, 3)
>  #define TMP421_CONVERSION_RATE_REG		0x0B
>  #define TMP421_N_FACTOR_REG_1			0x21
>  #define TMP421_MANUFACTURER_ID_REG		0xFE
> @@ -162,6 +165,34 @@ static int tmp421_update_device(struct tmp421_data *data)
>  	return 0;
>  }
>  
> +static int tmp421_enable_channels(struct tmp421_data *data)
> +{
> +	int err;
> +	struct i2c_client *client = data->client;
> +	struct device *dev = &client->dev;
> +	int old = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_2);
> +	int new, i;
> +
> +	if (old < 0) {
> +		dev_err(dev, "error reading register, can't disable channels\n");
> +		return old;
> +	}
> +
> +	new = old & ~TMP421_CONFIG_REG_REN_MASK;
> +	for (i = 0; i < data->channels; i++)
> +		if (data->channel[i].enabled)
> +			new |= TMP421_CONFIG_REG_REN(i);
> +
> +	if (new == old)
> +		return 0;
> +
> +	err = i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_2, new);
> +	if (err < 0)
> +		dev_err(dev, "error writing register, can't disable channels\n");
> +
> +	return err;
> +}
> +
>  static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
>  		       u32 attr, int channel, long *val)
>  {
> @@ -217,9 +248,10 @@ static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
>  	}
>  }
>  
> -static int tmp421_init_client(struct i2c_client *client)
> +static int tmp421_init_client(struct tmp421_data *data)
>  {
>  	int config, config_orig;
> +	struct i2c_client *client = data->client;
>  
>  	/* Set the conversion rate to 2 Hz */
>  	i2c_smbus_write_byte_data(client, TMP421_CONVERSION_RATE_REG, 0x05);
> @@ -240,7 +272,7 @@ static int tmp421_init_client(struct i2c_client *client)
>  		i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_1, config);
>  	}
>  
> -	return 0;
> +	return tmp421_enable_channels(data);
>  }
>  
>  static int tmp421_detect(struct i2c_client *client,
> @@ -391,10 +423,6 @@ static int tmp421_probe(struct i2c_client *client)
>  		data->channels = i2c_match_id(tmp421_id, client)->driver_data;
>  	data->client = client;
>  
> -	err = tmp421_init_client(client);
> -	if (err)
> -		return err;
> -
>  	for (i = 0; i < data->channels; i++) {
>  		data->temp_config[i] = HWMON_T_INPUT | HWMON_T_FAULT;
>  		data->channel[i].enabled = true;
> @@ -404,6 +432,10 @@ static int tmp421_probe(struct i2c_client *client)
>  	if (err)
>  		return err;
>  
> +	err = tmp421_init_client(data);
> +	if (err)
> +		return err;
> +
>  	data->chip.ops = &tmp421_ops;
>  	data->chip.info = data->info;
>