The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From c2980c64c7fd4585d684574c92d1624d44961edd Mon Sep 17 00:00:00 2001
From: Hui Liu <hui.liu@xxxxxxxxxxxx>
Date: Sun, 26 Sep 2021 15:30:28 +0800
Subject: [PATCH] iio: mtk-auxadc: fix case IIO_CHAN_INFO_PROCESSED
The previous driver does't apply the necessary scaling to take the
voltage range into account.
We change readback value from raw data to input voltage to fix case
IIO_CHAN_INFO_PROCESSED.
Fixes: ace4cdfe67be ("iio: adc: mt2701: Add Mediatek auxadc driver for mt2701.")
Signed-off-by: Hui Liu <hui.liu@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210926073028.11045-2-hui.liu@xxxxxxxxxxxx
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
diff --git a/drivers/iio/adc/mt6577_auxadc.c b/drivers/iio/adc/mt6577_auxadc.c
index 79c1dd68b909..d4fccd52ef08 100644
--- a/drivers/iio/adc/mt6577_auxadc.c
+++ b/drivers/iio/adc/mt6577_auxadc.c
@@ -82,6 +82,10 @@ static const struct iio_chan_spec mt6577_auxadc_iio_channels[] = {
MT6577_AUXADC_CHANNEL(15),
};
+/* For Voltage calculation */
+#define VOLTAGE_FULL_RANGE 1500 /* VA voltage */
+#define AUXADC_PRECISE 4096 /* 12 bits */
+
static int mt_auxadc_get_cali_data(int rawdata, bool enable_cali)
{
return rawdata;
@@ -191,6 +195,10 @@ static int mt6577_auxadc_read_raw(struct iio_dev *indio_dev,
}
if (adc_dev->dev_comp->sample_data_cali)
*val = mt_auxadc_get_cali_data(*val, true);
+
+ /* Convert adc raw data to voltage: 0 - 1500 mV */
+ *val = *val * VOLTAGE_FULL_RANGE / AUXADC_PRECISE;
+
return IIO_VAL_INT;
default:
