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authorChris Lesiak <chris.lesiak@licor.com>2015-06-01 11:27:37 -0500
committerGuenter Roeck <linux@roeck-us.net>2015-06-02 06:53:50 -0700
commit0315253b19bbc63eedad2f6125c21e280c76e29b (patch)
tree67997e9f452d6db148be106e492df5aaff165c8c /drivers/hwmon
parente892b75ff579a0c07b633f2e234aeecf78a93a37 (diff)
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>
Diffstat (limited to 'drivers/hwmon')
-rw-r--r--drivers/hwmon/ntc_thermistor.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index fca92912269e..3a2484aba57e 100644
--- a/drivers/hwmon/ntc_thermistor.c
+++ b/drivers/hwmon/ntc_thermistor.c
@@ -228,20 +228,21 @@ struct ntc_data {
static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
{
struct iio_channel *channel = pdata->chan;
- s64 result;
- int val, ret;
+ int raw, uv, ret;
- ret = iio_read_channel_raw(channel, &val);
+ ret = iio_read_channel_raw(channel, &raw);
if (ret < 0) {
pr_err("read channel() error: %d\n", ret);
return ret;
}
- /* unit: mV */
- result = pdata->pullup_uv * (s64) val;
- result >>= 12;
+ ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000);
+ if (ret < 0) {
+ /* Assume 12 bit ADC with vref at pullup_uv */
+ uv = (pdata->pullup_uv * (s64)raw) >> 12;
+ }
- return (int)result;
+ return uv;
}
static const struct of_device_id ntc_match[] = {