[PATCH v8 2/4] drivers: hwmon: sophgo: Add SG2042 external hardware monitor support

[Inochi Amaoto]

On Wed, Jul 31, 2024 at 02:13:20PM GMT, Chen Wang wrote:
> 
> On 2024/7/30 15:50, Inochi Amaoto wrote:
> [......]
> > +#define REG_CRITICAL_ACTIONS			0x65
> The name "REG_CRITICAL_ACTIONS" is ambiguous. I have confirmed with sophgo
> engineers that the complete process is: when the measured temperature
> exceeds the temperature set by REG_CRITICAL_TEMP, the processor is powered
> off and shut down, and then after the temperature returns to the temperature
> set by REG_REPOWER_TEMP, it is decided whether to power on again or remain
> in the shutdown state based on the action set by REG_CRITICAL_ACTIONS,
> whether it is reboot or poweroff.
> 
> So based on the above description, I think it would be better to
> call "REG_CRITICAL_ACTIONS" as "REG_REPOWER_ACTIONS". "REG_CRITICAL_ACTIONS"
> gives people the first impression that it is used to set actions related to
> REG_CRITICAL_TEMP.
> 
> It is also recommended to add the above description of temperature control
> and action settings in the code. Currently, sophgo does not have a clear
> document description for this part, and adding it will help us understand
> its functions.
> 
> Adding sophgo engineers Chunzhi and Haijiao, FYI.
> 
> > +#define REG_CRITICAL_TEMP			0x66
> > +#define REG_REPOWER_TEMP			0x67
> > +
> > +#define CRITICAL_ACTION_REBOOT			1
> > +#define CRITICAL_ACTION_POWEROFF		2
> 
> As I said upon, actions are not related to critical, but is for restoring
> from critical, suggest to give a better name.
> 
> [......]
> 
> > +static ssize_t critical_action_show(struct device *dev,
> [......]
> > +static ssize_t critical_action_store(struct device *dev,
> 
> [......]
> 
> The same reason as upon, "critical_action_xxx" is misleading.
> 
> [......]
> 

Thanks for explanation, I just get the name from the driver of SG2042.
This is out of my knowledge.

> > +static int sg2042_mcu_read_temp(struct device *dev,
> > +				u32 attr, int channel,
> > +				long *val)
> > +{
> > +	struct sg2042_mcu_data *mcu = dev_get_drvdata(dev);
> > +	int tmp;
> > +	u8 reg;
> > +
> > +	switch (attr) {
> > +	case hwmon_temp_input:
> > +		reg = channel ? REG_BOARD_TEMP : REG_SOC_TEMP;
> > +		break;
> > +	case hwmon_temp_crit:
> > +		reg = REG_CRITICAL_TEMP;
> > +		break;
> > +	case hwmon_temp_crit_hyst:
> > +		reg = REG_REPOWER_TEMP;
> > +		break;
> > +	default:
> > +		return -EOPNOTSUPP;
> > +	}
> > +
> > +	tmp = i2c_smbus_read_byte_data(mcu->client, reg);
> > +	if (tmp < 0)
> > +		return tmp;
> > +	*val = tmp * 1000;
> > +
> > +	return 0;
> > +}
> > +
> > +static int sg2042_mcu_read(struct device *dev,
> > +			   enum hwmon_sensor_types type,
> > +			   u32 attr, int channel, long *val)
> > +{
> > +	return sg2042_mcu_read_temp(dev, attr, channel, val);
> > +}
> Can we merge sg2042_mcu_read and sg2042_mcu_read_temp？

Yes, it can be merged. but I think using this nested function 
is more clear. And gcc can auto inline this function so we
got no performance penalty.

> > +
> > +static int sg2042_mcu_write(struct device *dev,
> > +			    enum hwmon_sensor_types type,
> > +			    u32 attr, int channel, long val)
> > +{
> > +	struct sg2042_mcu_data *mcu = dev_get_drvdata(dev);
> > +	int temp = val / 1000;
> > +	int hyst_temp, crit_temp;
> > +	int ret;
> > +	u8 reg;
> > +
> > +	if (temp > MCU_POWER_MAX)
> > +		temp = MCU_POWER_MAX;
> > +
> > +	mutex_lock(&mcu->mutex);
> > +
> > +	switch (attr) {
> > +	case hwmon_temp_crit:
> > +		hyst_temp = i2c_smbus_read_byte_data(mcu->client,
> > +						     REG_REPOWER_TEMP);
> > +		if (hyst_temp < 0) {
> > +			ret = -ENODEV;
> > +			goto failed;
> > +		}
> > +
> > +		crit_temp = temp;
> > +		reg = REG_CRITICAL_TEMP;
> > +		break;
> > +	case hwmon_temp_crit_hyst:
> > +		crit_temp = i2c_smbus_read_byte_data(mcu->client,
> > +						     REG_CRITICAL_TEMP);
> > +		if (crit_temp < 0) {
> > +			ret = -ENODEV;
> > +			goto failed;
> > +		}
> > +
> > +		hyst_temp = temp;
> > +		reg = REG_REPOWER_TEMP;
> > +		break;
> > +	default:
> > +		mutex_unlock(&mcu->mutex);
> > +		return -EOPNOTSUPP;
> > +	}
> > +
> It is recommended to add some comments to explain why we need to ensure that
> crit_temp is greater than or equal to hyst_temp. This is entirely because
> the current MCU does not limit the input, which may cause user to set
> incorrect crit_temp and hyst_temp.

Yeah, this is good idea.

> > +	if (crit_temp < hyst_temp) {
> > +		ret = -EINVAL;
> > +		goto failed;
> > +	}
> > +
> > +	ret = i2c_smbus_write_byte_data(mcu->client, reg, temp);
> > +
> > +failed:
> > +	mutex_unlock(&mcu->mutex);
> > +	return ret;
> > +}
> > +
> [......]