From 0315253b19bbc63eedad2f6125c21e280c76e29b Mon Sep 17 00:00:00 2001 From: Chris Lesiak Date: Mon, 1 Jun 2015 11:27:37 -0500 Subject: 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 Signed-off-by: Guenter Roeck --- drivers/hwmon/ntc_thermistor.c | 15 ++++++++------- 1 file 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[] = { -- cgit v1.2.3