patch "iio: adc: axp288: Fix TS-pin handling" added to staging-linus

index 031d568b4972..4e339cfd0c54 100644
@@ -27,9 +27,18 @@
 #include <linux/iio/machine.h>
 #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
+/*
+ * This mask enables all ADCs except for the battery temp-sensor (TS), that is
+ * left as-is to avoid breaking charging on devices without a temp-sensor.
+ */
+#define AXP288_ADC_EN_MASK				0xF0
+#define AXP288_ADC_TS_ENABLE				0x01
+
+#define AXP288_ADC_TS_CURRENT_ON_OFF_MASK		GENMASK(1, 0)
+#define AXP288_ADC_TS_CURRENT_OFF			(0 << 0)
+#define AXP288_ADC_TS_CURRENT_ON_WHEN_CHARGING		(1 << 0)
+#define AXP288_ADC_TS_CURRENT_ON_ONDEMAND		(2 << 0)
+#define AXP288_ADC_TS_CURRENT_ON			(3 << 0)
 
 enum axp288_adc_id {
 	AXP288_ADC_TS,

@@ -44,6 +53,7 @@ enum axp288_adc_id {
 struct axp288_adc_info {
 	int irq;
 	struct regmap *regmap;
+	bool ts_enabled;
 };
 
 static const struct iio_chan_spec axp288_adc_channels[] = {

@@ -115,21 +125,33 @@ 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)
+/*
+ * The current-source used for the battery temp-sensor (TS) is shared
+ * with the GPADC. For proper fuel-gauge and charger operation the TS
+ * current-source needs to be permanently on. But to read the GPADC we
+ * need to temporary switch the TS current-source to ondemand, so that
+ * the GPADC can use it, otherwise we will always read an all 0 value.
+ */
+static int axp288_adc_set_ts(struct axp288_adc_info *info,
+			     unsigned int mode, unsigned long address)
 {
 	int ret;
 
-	/* channels other than GPADC do not need to switch TS pin */
+	/* No need to switch the current-source if the TS pin is disabled */
+	if (!info->ts_enabled)
+		return 0;
+
+	/* Channels other than GPADC do not need the current source */
 	if (address != AXP288_GP_ADC_H)
 		return 0;
 
-	ret = regmap_write(regmap, AXP288_ADC_TS_PIN_CTRL, mode);
+	ret = regmap_update_bits(info->regmap, AXP288_ADC_TS_PIN_CTRL,
+				 AXP288_ADC_TS_CURRENT_ON_OFF_MASK, mode);
 	if (ret)
 		return ret;
 
 	/* When switching to the GPADC pin give things some time to settle */
-	if (mode == AXP288_ADC_TS_PIN_GPADC)
+	if (mode == AXP288_ADC_TS_CURRENT_ON_ONDEMAND)
 		usleep_range(6000, 10000);
 
 	return 0;

@@ -145,14 +167,14 @@ 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,
+		if (axp288_adc_set_ts(info, AXP288_ADC_TS_CURRENT_ON_ONDEMAND,
 					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,
+		if (axp288_adc_set_ts(info, AXP288_ADC_TS_CURRENT_ON,
 						chan->address))
 			dev_err(&indio_dev->dev, "TS pin restore\n");
 		break;

@@ -164,13 +186,35 @@ static int axp288_adc_read_raw(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static int axp288_adc_set_state(struct regmap *regmap)
+static int axp288_adc_initialize(struct axp288_adc_info *info)
 {
-	/* 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;
+	int ret, adc_enable_val;
+
+	/*
+	 * Determine if the TS pin is enabled and set the TS current-source
+	 * accordingly.
+	 */
+	ret = regmap_read(info->regmap, AXP20X_ADC_EN1, &adc_enable_val);
+	if (ret)
+		return ret;
+
+	if (adc_enable_val & AXP288_ADC_TS_ENABLE) {
+		info->ts_enabled = true;
+		ret = regmap_update_bits(info->regmap, AXP288_ADC_TS_PIN_CTRL,
+					 AXP288_ADC_TS_CURRENT_ON_OFF_MASK,
+					 AXP288_ADC_TS_CURRENT_ON);
+	} else {
+		info->ts_enabled = false;
+		ret = regmap_update_bits(info->regmap, AXP288_ADC_TS_PIN_CTRL,
+					 AXP288_ADC_TS_CURRENT_ON_OFF_MASK,
+					 AXP288_ADC_TS_CURRENT_OFF);
+	}
+	if (ret)
+		return ret;
 
-	return regmap_write(regmap, AXP20X_ADC_EN1, AXP288_ADC_EN_MASK);
+	/* Turn on the ADC for all channels except TS, leave TS as is */
+	return regmap_update_bits(info->regmap, AXP20X_ADC_EN1,
+				  AXP288_ADC_EN_MASK, AXP288_ADC_EN_MASK);
 }
 
 static const struct iio_info axp288_adc_iio_info = {

@@ -200,7 +244,7 @@ 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 = axp288_adc_set_state(axp20x->regmap);
+	ret = axp288_adc_initialize(info);
 	if (ret) {
 		dev_err(&pdev->dev, "unable to enable ADC device\n");
 		return ret;