iio: adc: add support for Allwinner SoCs ADC

The Allwinner SoCs all have an ADC that can also act as a touchscreen
controller and a thermal sensor. This patch adds the ADC driver which is
based on the MFD for the same SoCs ADC.

This also registers the thermal adc channel in the iio map array so
iio_hwmon could use it without modifying the Device Tree. This registers
the driver in the thermal framework.

The thermal sensor requires the IP to be in touchscreen mode to return
correct values. Therefore, if the user is continuously reading the ADC
channel(s), the thermal framework in which the thermal sensor is
registered will switch the IP in touchscreen mode to get a temperature
value and requires a delay of 100ms (because of the mode switching),
then the ADC will switch back to ADC mode and requires also a delay of
100ms. If the ADC readings are critical to user and the SoC temperature
is not, this driver is capable of not registering the thermal sensor in
the thermal framework and thus, "quicken" the ADC readings.

This driver probes on three different platform_device_id to take into
account slight differences (registers bit and temperature computation)
between Allwinner SoCs ADCs.
Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/Kconfig

@@ -559,6 +559,23 @@ config STX104
 	  The base port addresses for the devices may be configured via the base
 	  array module parameter.
 
+config SUN4I_GPADC
+	tristate "Support for the Allwinner SoCs GPADC"
+	depends on IIO
+	depends on MFD_SUN4I_GPADC
+	help
+	  Say yes here to build support for Allwinner (A10, A13 and A31) SoCs
+	  GPADC. This ADC provides 4 channels which can be used as an ADC or as
+	  a touchscreen input and one channel for thermal sensor.
+
+	  The thermal sensor slows down ADC readings and can be disabled by
+	  disabling CONFIG_THERMAL_OF. However, the thermal sensor should be
+	  enabled by default since the SoC temperature is usually more critical
+	  than ADC readings.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called sun4i-gpadc-iio.
+
 config TI_ADC081C
 	tristate "Texas Instruments ADC081C/ADC101C/ADC121C family"
 	depends on I2C

drivers/iio/adc/Makefile

@@ -49,6 +49,7 @@ obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_SPEAR_ADC) += spear_adc.o
 obj-$(CONFIG_STX104) += stx104.o
+obj-$(CONFIG_SUN4I_GPADC) += sun4i-gpadc-iio.o
 obj-$(CONFIG_STM32_ADC_CORE) += stm32-adc-core.o
 obj-$(CONFIG_STM32_ADC) += stm32-adc.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o

drivers/iio/adc/sun4i-gpadc-iio.c

+/* ADC driver for sunxi platforms' (A10, A13 and A31) GPADC
+ *
+ * Copyright (c) 2016 Quentin Schulz <quentin.schulz@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation.
+ *
+ * The Allwinner SoCs all have an ADC that can also act as a touchscreen
+ * controller and a thermal sensor.
+ * The thermal sensor works only when the ADC acts as a touchscreen controller
+ * and is configured to throw an interrupt every fixed periods of time (let say
+ * every X seconds).
+ * One would be tempted to disable the IP on the hardware side rather than
+ * disabling interrupts to save some power but that resets the internal clock of
+ * the IP, resulting in having to wait X seconds every time we want to read the
+ * value of the thermal sensor.
+ * This is also the reason of using autosuspend in pm_runtime. If there was no
+ * autosuspend, the thermal sensor would need X seconds after every
+ * pm_runtime_get_sync to get a value from the ADC. The autosuspend allows the
+ * thermal sensor to be requested again in a certain time span before it gets
+ * shutdown for not being used.
+ */
+
+#include <linux/completion.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/thermal.h>
+#include <linux/delay.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+#include <linux/iio/machine.h>
+#include <linux/mfd/sun4i-gpadc.h>
+
+static unsigned int sun4i_gpadc_chan_select(unsigned int chan)
+{
+	return SUN4I_GPADC_CTRL1_ADC_CHAN_SELECT(chan);
+}
+
+static unsigned int sun6i_gpadc_chan_select(unsigned int chan)
+{
+	return SUN6I_GPADC_CTRL1_ADC_CHAN_SELECT(chan);
+}
+
+struct gpadc_data {
+	int		temp_offset;
+	int		temp_scale;
+	unsigned int	tp_mode_en;
+	unsigned int	tp_adc_select;
+	unsigned int	(*adc_chan_select)(unsigned int chan);
+	unsigned int	adc_chan_mask;
+};
+
+static const struct gpadc_data sun4i_gpadc_data = {
+	.temp_offset = -1932,
+	.temp_scale = 133,
+	.tp_mode_en = SUN4I_GPADC_CTRL1_TP_MODE_EN,
+	.tp_adc_select = SUN4I_GPADC_CTRL1_TP_ADC_SELECT,
+	.adc_chan_select = &sun4i_gpadc_chan_select,
+	.adc_chan_mask = SUN4I_GPADC_CTRL1_ADC_CHAN_MASK,
+};
+
+static const struct gpadc_data sun5i_gpadc_data = {
+	.temp_offset = -1447,
+	.temp_scale = 100,
+	.tp_mode_en = SUN4I_GPADC_CTRL1_TP_MODE_EN,
+	.tp_adc_select = SUN4I_GPADC_CTRL1_TP_ADC_SELECT,
+	.adc_chan_select = &sun4i_gpadc_chan_select,
+	.adc_chan_mask = SUN4I_GPADC_CTRL1_ADC_CHAN_MASK,
+};
+
+static const struct gpadc_data sun6i_gpadc_data = {
+	.temp_offset = -1623,
+	.temp_scale = 167,
+	.tp_mode_en = SUN6I_GPADC_CTRL1_TP_MODE_EN,
+	.tp_adc_select = SUN6I_GPADC_CTRL1_TP_ADC_SELECT,
+	.adc_chan_select = &sun6i_gpadc_chan_select,
+	.adc_chan_mask = SUN6I_GPADC_CTRL1_ADC_CHAN_MASK,
+};
+
+struct sun4i_gpadc_iio {
+	struct iio_dev			*indio_dev;
+	struct completion		completion;
+	int				temp_data;
+	u32				adc_data;
+	struct regmap			*regmap;
+	unsigned int			fifo_data_irq;
+	atomic_t			ignore_fifo_data_irq;
+	unsigned int			temp_data_irq;
+	atomic_t			ignore_temp_data_irq;
+	const struct gpadc_data		*data;
+	/* prevents concurrent reads of temperature and ADC */
+	struct mutex			mutex;
+};
+
+#define SUN4I_GPADC_ADC_CHANNEL(_channel, _name) {		\
+	.type = IIO_VOLTAGE,					\
+	.indexed = 1,						\
+	.channel = _channel,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+	.datasheet_name = _name,				\
+}
+
+static struct iio_map sun4i_gpadc_hwmon_maps[] = {
+	{
+		.adc_channel_label = "temp_adc",
+		.consumer_dev_name = "iio_hwmon.0",
+	},
+	{ /* sentinel */ },
+};
+
+static const struct iio_chan_spec sun4i_gpadc_channels[] = {
+	SUN4I_GPADC_ADC_CHANNEL(0, "adc_chan0"),
+	SUN4I_GPADC_ADC_CHANNEL(1, "adc_chan1"),
+	SUN4I_GPADC_ADC_CHANNEL(2, "adc_chan2"),
+	SUN4I_GPADC_ADC_CHANNEL(3, "adc_chan3"),
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_OFFSET),
+		.datasheet_name = "temp_adc",
+	},
+};
+
+static const struct iio_chan_spec sun4i_gpadc_channels_no_temp[] = {
+	SUN4I_GPADC_ADC_CHANNEL(0, "adc_chan0"),
+	SUN4I_GPADC_ADC_CHANNEL(1, "adc_chan1"),
+	SUN4I_GPADC_ADC_CHANNEL(2, "adc_chan2"),
+	SUN4I_GPADC_ADC_CHANNEL(3, "adc_chan3"),
+};
+
+static int sun4i_prepare_for_irq(struct iio_dev *indio_dev, int channel,
+				 unsigned int irq)
+{
+	struct sun4i_gpadc_iio *info = iio_priv(indio_dev);
+	int ret;
+	u32 reg;
+
+	pm_runtime_get_sync(indio_dev->dev.parent);
+
+	reinit_completion(&info->completion);
+
+	ret = regmap_write(info->regmap, SUN4I_GPADC_INT_FIFOC,
+			   SUN4I_GPADC_INT_FIFOC_TP_FIFO_TRIG_LEVEL(1) |
+			   SUN4I_GPADC_INT_FIFOC_TP_FIFO_FLUSH);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(info->regmap, SUN4I_GPADC_CTRL1, &reg);
+	if (ret)
+		return ret;
+
+	if (irq == info->fifo_data_irq) {
+		ret = regmap_write(info->regmap, SUN4I_GPADC_CTRL1,
+				   info->data->tp_mode_en |
+				   info->data->tp_adc_select |
+				   info->data->adc_chan_select(channel));
+		/*
+		 * When the IP changes channel, it needs a bit of time to get
+		 * correct values.
+		 */
+		if ((reg & info->data->adc_chan_mask) !=
+			 info->data->adc_chan_select(channel))
+			mdelay(10);
+
+	} else {
+		/*
+		 * The temperature sensor returns valid data only when the ADC
+		 * operates in touchscreen mode.
+		 */
+		ret = regmap_write(info->regmap, SUN4I_GPADC_CTRL1,
+				   info->data->tp_mode_en);
+	}
+
+	if (ret)
+		return ret;
+
+	/*
+	 * When the IP changes mode between ADC or touchscreen, it
+	 * needs a bit of time to get correct values.
+	 */
+	if ((reg & info->data->tp_adc_select) != info->data->tp_adc_select)
+		mdelay(100);
+
+	return 0;
+}
+
+static int sun4i_gpadc_read(struct iio_dev *indio_dev, int channel, int *val,
+			    unsigned int irq)
+{
+	struct sun4i_gpadc_iio *info = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&info->mutex);
+
+	ret = sun4i_prepare_for_irq(indio_dev, channel, irq);
+	if (ret)
+		goto err;
+
+	enable_irq(irq);
+
+	/*
+	 * The temperature sensor throws an interruption periodically (currently
+	 * set at periods of ~0.6s in sun4i_gpadc_runtime_resume). A 1s delay
+	 * makes sure an interruption occurs in normal conditions. If it doesn't
+	 * occur, then there is a timeout.
+	 */
+	if (!wait_for_completion_timeout(&info->completion,
+					 msecs_to_jiffies(1000))) {
+		ret = -ETIMEDOUT;
+		goto err;
+	}
+
+	if (irq == info->fifo_data_irq)
+		*val = info->adc_data;
+	else
+		*val = info->temp_data;
+
+	ret = 0;
+	pm_runtime_mark_last_busy(indio_dev->dev.parent);
+
+err:
+	pm_runtime_put_autosuspend(indio_dev->dev.parent);
+	mutex_unlock(&info->mutex);
+
+	return ret;
+}
+
+static int sun4i_gpadc_adc_read(struct iio_dev *indio_dev, int channel,
+				int *val)
+{
+	struct sun4i_gpadc_iio *info = iio_priv(indio_dev);
+
+	return sun4i_gpadc_read(indio_dev, channel, val, info->fifo_data_irq);
+}
+
+static int sun4i_gpadc_temp_read(struct iio_dev *indio_dev, int *val)
+{
+	struct sun4i_gpadc_iio *info = iio_priv(indio_dev);
+
+	return sun4i_gpadc_read(indio_dev, 0, val, info->temp_data_irq);
+}
+
+static int sun4i_gpadc_temp_offset(struct iio_dev *indio_dev, int *val)
+{
+	struct sun4i_gpadc_iio *info = iio_priv(indio_dev);
+
+	*val = info->data->temp_offset;
+
+	return 0;
+}
+
+static int sun4i_gpadc_temp_scale(struct iio_dev *indio_dev, int *val)
+{
+	struct sun4i_gpadc_iio *info = iio_priv(indio_dev);
+
+	*val = info->data->temp_scale;
+
+	return 0;
+}
+
+static int sun4i_gpadc_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan, int *val,
+				int *val2, long mask)
+{
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_OFFSET:
+		ret = sun4i_gpadc_temp_offset(indio_dev, val);
+		if (ret)
+			return ret;
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type == IIO_VOLTAGE)
+			ret = sun4i_gpadc_adc_read(indio_dev, chan->channel,
+						   val);
+		else
+			ret = sun4i_gpadc_temp_read(indio_dev, val);
+
+		if (ret)
+			return ret;
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->type == IIO_VOLTAGE) {
+			/* 3000mV / 4096 * raw */
+			*val = 0;
+			*val2 = 732421875;
+			return IIO_VAL_INT_PLUS_NANO;
+		}
+
+		ret = sun4i_gpadc_temp_scale(indio_dev, val);
+		if (ret)
+			return ret;
+
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info sun4i_gpadc_iio_info = {
+	.read_raw = sun4i_gpadc_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static irqreturn_t sun4i_gpadc_temp_data_irq_handler(int irq, void *dev_id)
+{
+	struct sun4i_gpadc_iio *info = dev_id;
+
+	if (atomic_read(&info->ignore_temp_data_irq))
+		goto out;
+
+	if (!regmap_read(info->regmap, SUN4I_GPADC_TEMP_DATA, &info->temp_data))
+		complete(&info->completion);
+
+out:
+	disable_irq_nosync(info->temp_data_irq);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t sun4i_gpadc_fifo_data_irq_handler(int irq, void *dev_id)
+{
+	struct sun4i_gpadc_iio *info = dev_id;
+
+	if (atomic_read(&info->ignore_fifo_data_irq))
+		goto out;
+
+	if (!regmap_read(info->regmap, SUN4I_GPADC_DATA, &info->adc_data))
+		complete(&info->completion);
+
+out:
+	disable_irq_nosync(info->fifo_data_irq);
+	return IRQ_HANDLED;
+}
+
+static int sun4i_gpadc_runtime_suspend(struct device *dev)
+{
+	struct sun4i_gpadc_iio *info = iio_priv(dev_get_drvdata(dev));
+
+	/* Disable the ADC on IP */
+	regmap_write(info->regmap, SUN4I_GPADC_CTRL1, 0);
+	/* Disable temperature sensor on IP */
+	regmap_write(info->regmap, SUN4I_GPADC_TPR, 0);
+
+	return 0;
+}
+
+static int sun4i_gpadc_runtime_resume(struct device *dev)
+{
+	struct sun4i_gpadc_iio *info = iio_priv(dev_get_drvdata(dev));
+
+	/* clkin = 6MHz */
+	regmap_write(info->regmap, SUN4I_GPADC_CTRL0,
+		     SUN4I_GPADC_CTRL0_ADC_CLK_DIVIDER(2) |
+		     SUN4I_GPADC_CTRL0_FS_DIV(7) |
+		     SUN4I_GPADC_CTRL0_T_ACQ(63));
+	regmap_write(info->regmap, SUN4I_GPADC_CTRL1, info->data->tp_mode_en);
+	regmap_write(info->regmap, SUN4I_GPADC_CTRL3,
+		     SUN4I_GPADC_CTRL3_FILTER_EN |
+		     SUN4I_GPADC_CTRL3_FILTER_TYPE(1));
+	/* period = SUN4I_GPADC_TPR_TEMP_PERIOD * 256 * 16 / clkin; ~0.6s */
+	regmap_write(info->regmap, SUN4I_GPADC_TPR,
+		     SUN4I_GPADC_TPR_TEMP_ENABLE |
+		     SUN4I_GPADC_TPR_TEMP_PERIOD(800));
+
+	return 0;
+}
+
+static int sun4i_gpadc_get_temp(void *data, int *temp)
+{
+	struct sun4i_gpadc_iio *info = (struct sun4i_gpadc_iio *)data;
+	int val, scale, offset;
+
+	if (sun4i_gpadc_temp_read(info->indio_dev, &val))
+		return -ETIMEDOUT;
+
+	sun4i_gpadc_temp_scale(info->indio_dev, &scale);
+	sun4i_gpadc_temp_offset(info->indio_dev, &offset);
+
+	*temp = (val + offset) * scale;
+
+	return 0;
+}
+
+static const struct thermal_zone_of_device_ops sun4i_ts_tz_ops = {
+	.get_temp = &sun4i_gpadc_get_temp,
+};
+
+static const struct dev_pm_ops sun4i_gpadc_pm_ops = {
+	.runtime_suspend = &sun4i_gpadc_runtime_suspend,
+	.runtime_resume = &sun4i_gpadc_runtime_resume,
+};
+
+static int sun4i_irq_init(struct platform_device *pdev, const char *name,
+			  irq_handler_t handler, const char *devname,
+			  unsigned int *irq, atomic_t *atomic)
+{
+	int ret;
+	struct sun4i_gpadc_dev *mfd_dev = dev_get_drvdata(pdev->dev.parent);
+	struct sun4i_gpadc_iio *info = iio_priv(dev_get_drvdata(&pdev->dev));
+
+	/*
+	 * Once the interrupt is activated, the IP continuously performs
+	 * conversions thus throws interrupts. The interrupt is activated right
+	 * after being requested but we want to control when these interrupts
+	 * occur thus we disable it right after being requested. However, an
+	 * interrupt might occur between these two instructions and we have to
+	 * make sure that does not happen, by using atomic flags. We set the
+	 * flag before requesting the interrupt and unset it right after
+	 * disabling the interrupt. When an interrupt occurs between these two
+	 * instructions, reading the atomic flag will tell us to ignore the
+	 * interrupt.
+	 */
+	atomic_set(atomic, 1);
+
+	ret = platform_get_irq_byname(pdev, name);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "no %s interrupt registered\n", name);
+		return ret;
+	}
+
+	ret = regmap_irq_get_virq(mfd_dev->regmap_irqc, ret);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to get virq for irq %s\n", name);
+		return ret;
+	}
+
+	*irq = ret;
+	ret = devm_request_any_context_irq(&pdev->dev, *irq, handler, 0,
+					   devname, info);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "could not request %s interrupt: %d\n",
+			name, ret);
+		return ret;
+	}
+
+	disable_irq(*irq);
+	atomic_set(atomic, 0);
+
+	return 0;
+}
+
+static int sun4i_gpadc_probe(struct platform_device *pdev)
+{
+	struct sun4i_gpadc_iio *info;
+	struct iio_dev *indio_dev;
+	int ret;
+	struct sun4i_gpadc_dev *sun4i_gpadc_dev;
+
+	sun4i_gpadc_dev = 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);
+	platform_set_drvdata(pdev, indio_dev);
+
+	mutex_init(&info->mutex);
+	info->regmap = sun4i_gpadc_dev->regmap;
+	info->indio_dev = indio_dev;
+	init_completion(&info->completion);
+	indio_dev->name = dev_name(&pdev->dev);
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->dev.of_node = pdev->dev.of_node;
+	indio_dev->info = &sun4i_gpadc_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->num_channels = ARRAY_SIZE(sun4i_gpadc_channels);
+	indio_dev->channels = sun4i_gpadc_channels;
+
+	info->data = (struct gpadc_data *)platform_get_device_id(pdev)->driver_data;
+
+	/*
+	 * Since the controller needs to be in touchscreen mode for its thermal
+	 * sensor to operate properly, and that switching between the two modes
+	 * needs a delay, always registering in the thermal framework will
+	 * significantly slow down the conversion rate of the ADCs.
+	 *
+	 * Therefore, instead of depending on THERMAL_OF in Kconfig, we only
+	 * register the sensor if that option is enabled, eventually leaving
+	 * that choice to the user.
+	 */
+
+	if (IS_ENABLED(CONFIG_THERMAL_OF)) {
+		/*
+		 * This driver is a child of an MFD which has a node in the DT
+		 * but not its children, because of DT backward compatibility
+		 * for A10, A13 and A31 SoCs. Therefore, the resulting devices
+		 * of this driver do not have an of_node variable.
+		 * However, its parent (the MFD driver) has an of_node variable
+		 * and since devm_thermal_zone_of_sensor_register uses its first
+		 * argument to match the phandle defined in the node of the
+		 * thermal driver with the of_node of the device passed as first
+		 * argument and the third argument to call ops from
+		 * thermal_zone_of_device_ops, the solution is to use the parent
+		 * device as first argument to match the phandle with its
+		 * of_node, and the device from this driver as third argument to
+		 * return the temperature.
+		 */
+		struct thermal_zone_device *tzd;
+		tzd = devm_thermal_zone_of_sensor_register(pdev->dev.parent, 0,
+							   info,
+							   &sun4i_ts_tz_ops);
+		if (IS_ERR(tzd)) {
+			dev_err(&pdev->dev,
+				"could not register thermal sensor: %ld\n",
+				PTR_ERR(tzd));
+			ret = PTR_ERR(tzd);
+			goto err;
+		}
+	} else {
+		indio_dev->num_channels =
+			ARRAY_SIZE(sun4i_gpadc_channels_no_temp);
+		indio_dev->channels = sun4i_gpadc_channels_no_temp;
+	}
+
+	pm_runtime_set_autosuspend_delay(&pdev->dev,
+					 SUN4I_GPADC_AUTOSUSPEND_DELAY);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
+	if (IS_ENABLED(CONFIG_THERMAL_OF)) {
+		ret = sun4i_irq_init(pdev, "TEMP_DATA_PENDING",
+				     sun4i_gpadc_temp_data_irq_handler,
+				     "temp_data", &info->temp_data_irq,
+				     &info->ignore_temp_data_irq);
+		if (ret < 0)
+			goto err;
+	}
+
+	ret = sun4i_irq_init(pdev, "FIFO_DATA_PENDING",
+			     sun4i_gpadc_fifo_data_irq_handler, "fifo_data",
+			     &info->fifo_data_irq, &info->ignore_fifo_data_irq);
+	if (ret < 0)
+		goto err;
+
+	if (IS_ENABLED(CONFIG_THERMAL_OF)) {
+		ret = iio_map_array_register(indio_dev, sun4i_gpadc_hwmon_maps);
+		if (ret < 0) {
+			dev_err(&pdev->dev,
+				"failed to register iio map array\n");
+			goto err;
+		}
+	}
+
+	ret = devm_iio_device_register(&pdev->dev, indio_dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "could not register the device\n");
+		goto err_map;
+	}
+
+	return 0;
+
+err_map:
+	if (IS_ENABLED(CONFIG_THERMAL_OF))
+		iio_map_array_unregister(indio_dev);
+
+err:
+	pm_runtime_put(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
+	return ret;
+}
+
+static int sun4i_gpadc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+
+	pm_runtime_put(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+	if (IS_ENABLED(CONFIG_THERMAL_OF))
+		iio_map_array_unregister(indio_dev);
+
+	return 0;
+}
+
+static const struct platform_device_id sun4i_gpadc_id[] = {
+	{ "sun4i-a10-gpadc-iio", (kernel_ulong_t)&sun4i_gpadc_data },
+	{ "sun5i-a13-gpadc-iio", (kernel_ulong_t)&sun5i_gpadc_data },
+	{ "sun6i-a31-gpadc-iio", (kernel_ulong_t)&sun6i_gpadc_data },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver sun4i_gpadc_driver = {
+	.driver = {
+		.name = "sun4i-gpadc-iio",
+		.pm = &sun4i_gpadc_pm_ops,
+	},
+	.id_table = sun4i_gpadc_id,
+	.probe = sun4i_gpadc_probe,
+	.remove = sun4i_gpadc_remove,
+};
+
+module_platform_driver(sun4i_gpadc_driver);
+
+MODULE_DESCRIPTION("ADC driver for sunxi platforms");
+MODULE_AUTHOR("Quentin Schulz <quentin.schulz@free-electrons.com>");
+MODULE_LICENSE("GPL v2");

include/linux/mfd/sun4i-gpadc.h

@@ -28,6 +28,7 @@
 #define SUN4I_GPADC_CTRL1_TP_MODE_EN			BIT(4)
 #define SUN4I_GPADC_CTRL1_TP_ADC_SELECT			BIT(3)
 #define SUN4I_GPADC_CTRL1_ADC_CHAN_SELECT(x)		(GENMASK(2, 0) & (x))
+#define SUN4I_GPADC_CTRL1_ADC_CHAN_MASK			GENMASK(2, 0)
 
 /* TP_CTRL1 bits for sun6i SOCs */
 #define SUN6I_GPADC_CTRL1_TOUCH_PAN_CALI_EN		BIT(7)
@@ -35,6 +36,7 @@
 #define SUN6I_GPADC_CTRL1_TP_MODE_EN			BIT(5)
 #define SUN6I_GPADC_CTRL1_TP_ADC_SELECT			BIT(4)
 #define SUN6I_GPADC_CTRL1_ADC_CHAN_SELECT(x)		(GENMASK(3, 0) & BIT(x))
+#define SUN6I_GPADC_CTRL1_ADC_CHAN_MASK			GENMASK(3, 0)
 
 #define SUN4I_GPADC_CTRL2				0x08