Re: [PATCH v1 5/5] First approach to sample time writing method

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

On 7/9/19 2:50 AM, Iker Perez wrote:
> From: Iker Perez del Palomar Sustatxa <iker.perez@codethink.co.uk>
> 
> Switch between the possible update_time values and write into the
> configuration register the selected value.
> 
> Signed-off-by: Iker Perez del Palomar Sustatxa <iker.perez@codethink.co.uk>
> ---
>   drivers/hwmon/lm75.c | 43 ++++++++++++++++++++++++++++++++++---------
>   1 file changed, 34 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
> index 5ba7277dac69..9d48a85fd3e5 100644
> --- a/drivers/hwmon/lm75.c
> +++ b/drivers/hwmon/lm75.c
> @@ -156,21 +156,46 @@ static int lm75_read(struct device *dev, enum hwmon_sensor_types type,
>   }
>   
>   static int lm75_write(struct device *dev, enum hwmon_sensor_types type,
> -		      u32 attr, int channel, long temp)
> +		      u32 attr, int channel, long val)
>   {
>   	struct lm75_data *data = dev_get_drvdata(dev);
> -	u8 resolution;
> -	int reg;
> +	u8 resolution, set_mask, clr_mask;
> +	int reg, status;
> +
> +	// This are provisional changes, to be improved in case this approach works
> +	set_mask = 0;
> +	clr_mask = LM75_SHUTDOWN;
>   
>   	switch (type) {
>   	case hwmon_chip:
>   		switch (attr) {
>   		case hwmon_chip_update_interval:
> -			if (data->kind == tmp75b)
> -				pr_info("Iker inside write\n");
> +			if (data->kind == tmp75b) {
> +				clr_mask |= 1 << 15 | 0x3 << 13;
> +				switch (val) {
> +				case (27):
> +					set_mask |= 0x3 << 13;
> +					data->sample_time = MSEC_PER_SEC / 37;
> +						break;
> +				case (55):
> +					set_mask |= 0x2 << 13;
> +					data->sample_time = MSEC_PER_SEC / 18;
> +						break;
> +				case (111):
> +					set_mask |= 0x1 << 13;
> +					data->sample_time = MSEC_PER_SEC / 9;
> +						break;
> +				case (250):
> +					set_mask |= 0x0 << 13;
> +					data->sample_time = MSEC_PER_SEC / 4;
> +						break;
> +				default:
> +						return -EINVAL;
> +				status = configure_reg(set_mask, clr_mask, data, client);

You'll probably want to provide all the necessary variants (supported update times
as well as associated resolutions and set/clear masks) in the data structure,
to make it easy to support multiple chips. Either case, it is unacceptable to
only accept specific values: You can not expect the user to figure out individual
supported values on a per-chip basis. Please use something like find_closest()
to find the best match.

> +				}
> +			}
>   			else
>   				return -EINVAL;
> -			break;
>   		default:
>   			return -EINVAL;
>   		}
> @@ -195,11 +220,11 @@ static int lm75_write(struct device *dev, enum hwmon_sensor_types type,
>   		else
>   			resolution = data->resolution;
>   
> -		temp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX);
> -		temp = DIV_ROUND_CLOSEST(temp  << (resolution - 8),
> +		val = clamp_val(val, LM75_TEMP_MIN, LM75_TEMP_MAX);
> +		val = DIV_ROUND_CLOSEST(val  << (resolution - 8),
>   					 1000) << (16 - resolution);
>   
> -		return regmap_write(data->regmap, reg, temp);
> +		return regmap_write(data->regmap, reg, val);
>   	default:
>   		return -EINVAL;
>   	}
>