iio: adc: Revert "axp288: Drop bogus AXP288_ADC_TS_PIN_CTRL register modifications"

Inheriting the ADC BIAS current settings from the BIOS instead of
hardcoding then causes the AXP288 to disable charging (I think it
mis-detects an overheated battery) on at least one model tablet.

So lets go back to hard coding the values, this reverts
commit fa2849e9649b ("iio: adc: axp288: Drop bogus
AXP288_ADC_TS_PIN_CTRL register modifications"), fixing charging not
working on the model tablet in question.

The exact cause is not fully understood, hence the revert to a known working
state.

Cc: stable@vger.kernel.org
Reported-by: Umberto Ixxo <sfumato1977@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 31 insertions, 1 deletions

diff --git a/drivers/iio/adc/axp288_adc.c b/drivers/iio/adc/axp288_adc.c
index 64799ad7ebad..7fd24949c0c1 100644
--- a/drivers/iio/adc/axp288_adc.c
+++ b/drivers/iio/adc/axp288_adc.c
@@ -28,6 +28,8 @@
 #include <linux/iio/driver.h>
 
 #define AXP288_ADC_EN_MASK              0xF1
+#define AXP288_ADC_TS_PIN_GPADC         0xF2
+#define AXP288_ADC_TS_PIN_ON            0xF3
 
 enum axp288_adc_id {
         AXP288_ADC_TS,
@@ -121,6 +123,16 @@ static int axp288_adc_read_channel(int *val, unsigned long address,
         return IIO_VAL_INT;
 }
 
+static int axp288_adc_set_ts(struct regmap *regmap, unsigned int mode,
+                                unsigned long address)
+{
+        /* channels other than GPADC do not need to switch TS pin */
+        if (address != AXP288_GP_ADC_H)
+                return 0;
+
+        return regmap_write(regmap, AXP288_ADC_TS_PIN_CTRL, mode);
+}
+
 static int axp288_adc_read_raw(struct iio_dev *indio_dev,
                         struct iio_chan_spec const *chan,
                         int *val, int *val2, long mask)
@@ -131,7 +143,16 @@ static int axp288_adc_read_raw(struct iio_dev *indio_dev,
         mutex_lock(&indio_dev->mlock);
         switch (mask) {
         case IIO_CHAN_INFO_RAW:
+                if (axp288_adc_set_ts(info->regmap, AXP288_ADC_TS_PIN_GPADC,
+                                        chan->address)) {
+                        dev_err(&indio_dev->dev, "GPADC mode\n");
+                        ret = -EINVAL;
+                        break;
+                }
                 ret = axp288_adc_read_channel(val, chan->address, info->regmap);
+                if (axp288_adc_set_ts(info->regmap, AXP288_ADC_TS_PIN_ON,
+                                                chan->address))
+                        dev_err(&indio_dev->dev, "TS pin restore\n");
                 break;
         default:
                 ret = -EINVAL;
@@ -141,6 +162,15 @@ static int axp288_adc_read_raw(struct iio_dev *indio_dev,
         return ret;
 }
 
+static int axp288_adc_set_state(struct regmap *regmap)
+{
+        /* ADC should be always enabled for internal FG to function */
+        if (regmap_write(regmap, AXP288_ADC_TS_PIN_CTRL, AXP288_ADC_TS_PIN_ON))
+                return -EIO;
+
+        return regmap_write(regmap, AXP20X_ADC_EN1, AXP288_ADC_EN_MASK);
+}
+
 static const struct iio_info axp288_adc_iio_info = {
         .read_raw = &axp288_adc_read_raw,
         .driver_module = THIS_MODULE,
@@ -169,7 +199,7 @@ static int axp288_adc_probe(struct platform_device *pdev)
          * Set ADC to enabled state at all time, including system suspend.
          * otherwise internal fuel gauge functionality may be affected.
          */
-        ret = regmap_write(info->regmap, AXP20X_ADC_EN1, AXP288_ADC_EN_MASK);
+        ret = axp288_adc_set_state(axp20x->regmap);
         if (ret) {
                 dev_err(&pdev->dev, "unable to enable ADC device\n");
                 return ret;