Re: [PATCH RFC v2 3/5] thermal: qcom: Add support for MBG thermal monitoring

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 12.12.2024 5:11 PM, Satya Priya Kakitapalli wrote:
> Add driver for the MBG thermal monitoring device. It monitors
> the die temperature, and when there is a level 1 upper threshold
> violation, it receives an interrupt over spmi. The driver reads
> the fault status register and notifies thermal accordingly.
> 
> Signed-off-by: Satya Priya Kakitapalli <quic_skakitap@quicinc.com>
> ---

[...]

> +static const struct mbg_map_table map_table[] = {

Is this peripheral/pmic-specific?

> +	/* minT	vtemp0	tc */
> +	{ -60000, 4337, 1967 },
> +	{ -40000, 4731, 1964 },
> +	{ -20000, 5124, 1957  },
> +	{ 0,      5515, 1949 },
> +	{ 20000,  5905, 1940 },
> +	{ 40000,  6293, 1930 },
> +	{ 60000,  6679, 1921 },
> +	{ 80000,  7064, 1910 },
> +	{ 100000, 7446, 1896 },
> +	{ 120000, 7825, 1878 },
> +	{ 140000, 8201, 1859 },
> +};
> +
> +static int mbg_tm_get_temp(struct thermal_zone_device *tz, int *temp)
> +{
> +	struct mbg_tm_chip *chip = thermal_zone_device_priv(tz);
> +	int ret, milli_celsius;
> +
> +	if (!temp)
> +		return -EINVAL;
> +
> +	if (chip->last_thres_crossed) {
> +		pr_debug("last_temp: %d\n", chip->last_temp);

Use dev_dbg for consistency with the other debug prints

> +		chip->last_thres_crossed = false;
> +		*temp = chip->last_temp;
> +		return 0;
> +	}
> +
> +	ret = iio_read_channel_processed(chip->adc, &milli_celsius);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "failed to read iio channel %d\n", ret);
> +		return ret;
> +	}
> +
> +	*temp = milli_celsius;
> +
> +	return 0;
> +}
> +
> +static int temp_to_vtemp(int temp)
> +{
> +
> +	int idx, vtemp, tc = 0, t0 = 0, vtemp0 = 0;
> +
> +	for (idx = 0; idx < ARRAY_SIZE(map_table); idx++)
> +		if (temp >= map_table[idx].min_temp &&
> +				temp < (map_table[idx].min_temp + 20000)) {

Please align the two lines, tab width is 8 for kernel code

> +			tc = map_table[idx].tc;
> +			t0 = map_table[idx].min_temp;
> +			vtemp0 = map_table[idx].vtemp0;
> +			break;
> +		}
> +
> +	/*
> +	 * Formula to calculate vtemp(mV) from a given temp
> +	 * vtemp = (temp - minT) * tc + vtemp0
> +	 * tc, t0 and vtemp0 values are mentioned in the map_table array.
> +	 */
> +	vtemp = ((temp - t0) * tc + vtemp0 * 100000) / 1000000;

So you say vtemp = ... and the func is called temp_to_vtemp

> +	return abs(vtemp - MBG_TEMP_DEFAULT_TEMP_MV) / MBG_TEMP_STEP_MV;

But you end up returning a scaled version of it..
Please clarify that in the code


> +}
> +
> +static int mbg_tm_set_trip_temp(struct thermal_zone_device *tz, int low_temp,
> +						int temp)
> +{
> +	struct mbg_tm_chip *chip = thermal_zone_device_priv(tz);
> +	int ret = 0;
> +
> +	guard(mutex)(&chip->lock);
> +
> +	/* The HW has a limitation that the trip set must be above 25C */
> +	if (temp > MBG_MIN_TRIP_TEMP && temp < MBG_MAX_SUPPORTED_TEMP) {
> +		regmap_set_bits(chip->map,
> +			chip->base + MBG_TEMP_MON2_MISC_CFG, MON2_UP_THRESH_EN);
> +		ret = regmap_write(chip->map, chip->base + MON2_LVL1_UP_THRESH,
> +						temp_to_vtemp(temp));
> +		if (ret < 0)
> +			return ret;
> +	} else {
> +		dev_dbg(chip->dev, "Set trip b/w 25C and 160C\n");
> +		regmap_clear_bits(chip->map,
> +			chip->base + MBG_TEMP_MON2_MISC_CFG, MON2_UP_THRESH_EN);
> +	}
> +
> +	/*
> +	 * Configure the last_temp one degree higher, to ensure the
> +	 * violated temp is returned to thermal framework when it reads
> +	 * temperature for the first time after the violation happens.
> +	 * This is needed to account for the inaccuracy in the conversion
> +	 * formula used which leads to the thermal framework setting back
> +	 * the same thresholds in case the temperature it reads does not
> +	 * show violation.
> +	 */
> +	chip->last_temp = temp + MBG_TEMP_CONSTANT;
> +
> +	return ret;
> +}
> +
> +static const struct thermal_zone_device_ops mbg_tm_ops = {
> +	.get_temp = mbg_tm_get_temp,
> +	.set_trips = mbg_tm_set_trip_temp,
> +};
> +
> +static irqreturn_t mbg_tm_isr(int irq, void *data)
> +{
> +	struct mbg_tm_chip *chip = data;
> +	int ret, val;
> +
> +	scoped_guard(mutex, &chip->lock) {
> +		ret = regmap_read(chip->map,
> +			chip->base + MBG_TEMP_MON2_FAULT_STATUS, &val);
> +		if (ret < 0)
> +			return IRQ_HANDLED;
> +	}
> +
> +	if ((val & MON_FAULT_STATUS_MASK) & MON_FAULT_STATUS_LVL1) {
> +		if ((val & MON_POLARITY_STATUS_MASK) & MON_POLARITY_STATUS_UPR) {

Just checking the last argument to AND in both lines is enough, as
they're both parts of the bitfield

[...]

> +	ret = device_property_read_u32(chip->dev, "reg", &res);
> +	if (ret < 0)
> +		return ret;

return dev_err_probe(dev, ret, "Couldn't read reg property"\n);

> +
> +	chip->base = res;
> +
> +	chip->irq = platform_get_irq(pdev, 0);
> +	if (chip->irq < 0)
> +		return chip->irq;

Similarly here

> +
> +	chip->adc = devm_iio_channel_get(&pdev->dev, "thermal");
> +	if (IS_ERR(chip->adc))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(chip->adc),
> +			       "failed to get adc channel\n");
> +
> +	chip->tz_dev = devm_thermal_of_zone_register(&pdev->dev, 0,
> +						chip, &mbg_tm_ops);
> +	if (IS_ERR(chip->tz_dev))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(chip->tz_dev),
> +			       "failed to register sensor\n");

Please also make the error messages start with an uppercase letter

> +
> +	return devm_request_threaded_irq(&pdev->dev, chip->irq, NULL,
> +			mbg_tm_isr, IRQF_ONESHOT, node->name, chip);
> +}
> +
> +static const struct of_device_id mbg_tm_match_table[] = {
> +	{ .compatible = "qcom,spmi-pm8775-mbg-tm" },

I don't think the 'spmi' bit belongs here

Konrad