mirror of https://gitee.com/openkylin/linux.git
hwmon: (ntc_thermistor) fix iio raw to microvolts conversion
The function ntc_adc_iio_read was assuming both a 12 bit ADC and that pullup_uv is the same as the ADC reference voltage. If either assumption is false, then the result is incorrect. Attempt to use iio_convert_raw_to_processed to convert the raw value to microvolts. It will fail for iio channels that don't support support IIO_CHAN_INFO_SCALE; in that case fall back to the assumptions. Signed-off-by: Chris Lesiak <chris.lesiak@licor.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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0315253b19
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@ -228,20 +228,21 @@ struct ntc_data {
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static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
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{
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struct iio_channel *channel = pdata->chan;
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s64 result;
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int val, ret;
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int raw, uv, ret;
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ret = iio_read_channel_raw(channel, &val);
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ret = iio_read_channel_raw(channel, &raw);
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if (ret < 0) {
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pr_err("read channel() error: %d\n", ret);
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return ret;
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}
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/* unit: mV */
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result = pdata->pullup_uv * (s64) val;
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result >>= 12;
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ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000);
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if (ret < 0) {
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/* Assume 12 bit ADC with vref at pullup_uv */
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uv = (pdata->pullup_uv * (s64)raw) >> 12;
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}
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return (int)result;
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return uv;
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}
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static const struct of_device_id ntc_match[] = {
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