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linux/drivers/iio/adc/axp288_adc.c
Hans de Goede 3091141d78 iio: adc: axp288: Fix the GPADC pin reading often wrongly returning 0 
I noticed in its DSDT that one of my tablets actually is using the GPADC
pin for temperature monitoring.

The whole axp288_adc_set_ts() function is a bit weird, in the past it was
removed because it seems to make no sense, then this was reverted because
of regressions.

So I decided to test the special GPADC pin handling on this tablet.
Conclusion: not only is axp288_adc_set_ts() necessary, we need to sleep a
bit after making the AXP288_ADC_TS_PIN_CTRL changes before sampling the
GPADC, otherwise it will often (about 80% of the time) read 0 instead of
its actual value.

It seems that there is only 1 bias current source and to be able to use it
for the GPIO0 pin in GPADC mode it must be temporarily turned off for the
TS pin, but the datasheet does not mention this.

This commit adds a sleep after disabling the TS pin bias current,
fixing the GPADC more often then not wrongly returning 0.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2017-07-09 21:16:28 +01:00

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/*
* axp288_adc.c - X-Powers AXP288 PMIC ADC Driver
*
* Copyright (C) 2014 Intel Corporation
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/regmap.h>
#include <linux/mfd/axp20x.h>
#include <linux/platform_device.h>
#include <linux/iio/iio.h>
#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
enum axp288_adc_id {
AXP288_ADC_TS,
AXP288_ADC_PMIC,
AXP288_ADC_GP,
AXP288_ADC_BATT_CHRG_I,
AXP288_ADC_BATT_DISCHRG_I,
AXP288_ADC_BATT_V,
AXP288_ADC_NR_CHAN,
};
struct axp288_adc_info {
int irq;
struct regmap *regmap;
};
static const struct iio_chan_spec axp288_adc_channels[] = {
{
.indexed = 1,
.type = IIO_TEMP,
.channel = 0,
.address = AXP288_TS_ADC_H,
.datasheet_name = "TS_PIN",
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
}, {
.indexed = 1,
.type = IIO_TEMP,
.channel = 1,
.address = AXP288_PMIC_ADC_H,
.datasheet_name = "PMIC_TEMP",
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
}, {
.indexed = 1,
.type = IIO_TEMP,
.channel = 2,
.address = AXP288_GP_ADC_H,
.datasheet_name = "GPADC",
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
}, {
.indexed = 1,
.type = IIO_CURRENT,
.channel = 3,
.address = AXP20X_BATT_CHRG_I_H,
.datasheet_name = "BATT_CHG_I",
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
}, {
.indexed = 1,
.type = IIO_CURRENT,
.channel = 4,
.address = AXP20X_BATT_DISCHRG_I_H,
.datasheet_name = "BATT_DISCHRG_I",
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
}, {
.indexed = 1,
.type = IIO_VOLTAGE,
.channel = 5,
.address = AXP20X_BATT_V_H,
.datasheet_name = "BATT_V",
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
},
};
#define AXP288_ADC_MAP(_adc_channel_label, _consumer_dev_name, \
_consumer_channel) \
{ \
.adc_channel_label = _adc_channel_label, \
.consumer_dev_name = _consumer_dev_name, \
.consumer_channel = _consumer_channel, \
}
/* for consumer drivers */
static struct iio_map axp288_adc_default_maps[] = {
AXP288_ADC_MAP("TS_PIN", "axp288-batt", "axp288-batt-temp"),
AXP288_ADC_MAP("PMIC_TEMP", "axp288-pmic", "axp288-pmic-temp"),
AXP288_ADC_MAP("GPADC", "axp288-gpadc", "axp288-system-temp"),
AXP288_ADC_MAP("BATT_CHG_I", "axp288-chrg", "axp288-chrg-curr"),
AXP288_ADC_MAP("BATT_DISCHRG_I", "axp288-chrg", "axp288-chrg-d-curr"),
AXP288_ADC_MAP("BATT_V", "axp288-batt", "axp288-batt-volt"),
{},
};
static int axp288_adc_read_channel(int *val, unsigned long address,
struct regmap *regmap)
{
u8 buf[2];
if (regmap_bulk_read(regmap, address, buf, 2))
return -EIO;
*val = (buf[0] << 4) + ((buf[1] >> 4) & 0x0F);
return IIO_VAL_INT;
}
static int axp288_adc_set_ts(struct regmap *regmap, unsigned int mode,
unsigned long address)
{
int ret;
/* channels other than GPADC do not need to switch TS pin */
if (address != AXP288_GP_ADC_H)
return 0;
ret = regmap_write(regmap, AXP288_ADC_TS_PIN_CTRL, mode);
if (ret)
return ret;
/* When switching to the GPADC pin give things some time to settle */
if (mode == AXP288_ADC_TS_PIN_GPADC)
usleep_range(6000, 10000);
return 0;
}
static int axp288_adc_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
int ret;
struct axp288_adc_info *info = iio_priv(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;
}
mutex_unlock(&indio_dev->mlock);
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,
};
static int axp288_adc_probe(struct platform_device *pdev)
{
int ret;
struct axp288_adc_info *info;
struct iio_dev *indio_dev;
struct axp20x_dev *axp20x = dev_get_drvdata(pdev->dev.parent);
indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*info));
if (!indio_dev)
return -ENOMEM;
info = iio_priv(indio_dev);
info->irq = platform_get_irq(pdev, 0);
if (info->irq < 0) {
dev_err(&pdev->dev, "no irq resource?\n");
return info->irq;
}
platform_set_drvdata(pdev, indio_dev);
info->regmap = axp20x->regmap;
/*
* 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);
if (ret) {
dev_err(&pdev->dev, "unable to enable ADC device\n");
return ret;
}
indio_dev->dev.parent = &pdev->dev;
indio_dev->name = pdev->name;
indio_dev->channels = axp288_adc_channels;
indio_dev->num_channels = ARRAY_SIZE(axp288_adc_channels);
indio_dev->info = &axp288_adc_iio_info;
indio_dev->modes = INDIO_DIRECT_MODE;
ret = iio_map_array_register(indio_dev, axp288_adc_default_maps);
if (ret < 0)
return ret;
ret = iio_device_register(indio_dev);
if (ret < 0) {
dev_err(&pdev->dev, "unable to register iio device\n");
goto err_array_unregister;
}
return 0;
err_array_unregister:
iio_map_array_unregister(indio_dev);
return ret;
}
static int axp288_adc_remove(struct platform_device *pdev)
{
struct iio_dev *indio_dev = platform_get_drvdata(pdev);
iio_device_unregister(indio_dev);
iio_map_array_unregister(indio_dev);
return 0;
}
static const struct platform_device_id axp288_adc_id_table[] = {
{ .name = "axp288_adc" },
{},
};
static struct platform_driver axp288_adc_driver = {
.probe = axp288_adc_probe,
.remove = axp288_adc_remove,
.id_table = axp288_adc_id_table,
.driver = {
.name = "axp288_adc",
},
};
MODULE_DEVICE_TABLE(platform, axp288_adc_id_table);
module_platform_driver(axp288_adc_driver);
MODULE_AUTHOR("Jacob Pan <jacob.jun.pan@linux.intel.com>");
MODULE_DESCRIPTION("X-Powers AXP288 ADC Driver");
MODULE_LICENSE("GPL");
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