iio: adc: axp288: Fix TS-pin handling

Prior to this commit there were 3 issues with our handling of the TS-pin:

1) There are 2 ways how the firmware can disable monitoring of the TS-pin
for designs which do not have a temperature-sensor for the battery:
a) Clearing bit 0 of the AXP20X_ADC_EN1 register
b) Setting bit 2 of the AXP288_ADC_TS_PIN_CTRL monitoring

Prior to this commit we were unconditionally setting both bits to the
value used on devices with a TS. This causes the temperature protection to
kick in on devices without a TS, such as the Jumper ezbook v2, causing
them to not charge under Linux.

This commit fixes this by using regmap_update_bits when updating these 2
registers, leaving the 2 mentioned bits alone.

The next 2 problems are related to our handling of the current-source
for the TS-pin. 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.

2) Problem 2 is we were writing hardcoded values to the ADC TS pin-ctrl
register, overwriting various other unrelated bits. Specifically we were
overwriting the current-source setting for the TS and GPIO0 pins, forcing
it to 80ųA independent of its original setting. On a Chuwi Vi10 tablet
this was causing us to get a too high adc value (due to a too high
current-source) resulting in the following errors being logged:

ACPI Error: AE_ERROR, Returned by Handler for [UserDefinedRegion]
ACPI Error: Method parse/execution failed \_SB.SXP1._TMP, AE_ERROR

This commit fixes this by using regmap_update_bits to change only the
relevant bits.

3) After reading the GPADC channel we were unconditionally enabling the
TS current-source even on devices where the TS-pin is not used and the
current-source thus was off before axp288_adc_read_raw call.

This commit fixes this by making axp288_adc_set_ts a nop on devices where
the ADC is not enabled for the TS-pin.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1610545
Fixes: 3091141d7803 ("iio: adc: axp288: Fix the GPADC pin ...")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/axp288_adc.c b/drivers/iio/adc/axp288_adc.c
index 031d568..4e339cf 100644 (file)
--- a/drivers/iio/adc/axp288_adc.c
+++ b/drivers/iio/adc/axp288_adc.c
@@ -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;