Date:   Tue, 1 Nov 2016 18:09:55 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Quentin Schulz <quentin.schulz@...e-electrons.com>,
        jdelvare@...e.com, linux@...ck-us.net, knaack.h@....de,
        lars@...afoo.de, pmeerw@...erw.net,
        maxime.ripard@...e-electrons.com, wens@...e.org,
        lee.jones@...aro.org
Cc:     thomas.petazzoni@...e-electrons.com,
        antoine.tenart@...e-electrons.com, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v6 2/2] iio: adc: add support for Allwinner SoCs ADC

On 31/10/16 09:34, Quentin Schulz wrote:
> Hi Jonathan and Lee,
> 
> On 30/10/2016 17:59, Jonathan Cameron wrote:
>> On 15/09/16 13:44, Quentin Schulz wrote:
>>> 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.
>>>
>>> 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@...e-electrons.com>
>>> Acked-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
>>> Acked-by: Jonathan Cameron <jic23@...nel.org>
>> Hi Lee,
>>
>> As you applied the MFD part of this series, could you pick this up as well?
>>
> 
> Someone reported some bugs on the CHIP (sun5i-r8). I'm investigating that.
> 
> Also, it misses a scale for voltage (not that critical but still).
> 
> And also, Thomas Petazzoni just found a deadlock in sun4i_gpadc_read. If
> a regmap_write fails after getting the mutex, it is never released.
> 
> Is there some sort of deadline you want for a v7 since the mfd patch has
> been merged?
> 
No rush at all.  Doesn't matter as long as we know it's on it's way
sooner or later.  If it falls into the next cycle, that's fine -
I'll just pick it up directly as dependencies will in place by then.

Jonathan
> Thanks,
> Quentin
> 
>> Thanks,
>>
>> Jonathan
>>> ---
>>>
>>> v6:
>>>  - remove useless member (regs) from sun4i_gpadc_dev structure,
>>>  - rename sun4i_gpadc_dev structure to sun4i_gpadc_iio,
>>>  - remove regmap_update_bits used to disable hardware interrupts, it is already
>>>  handled by devm functions,
>>>
>>> v5:
>>>  - correct mail address,
>>>  - correct several typos,
>>>  - move from const to static for sunxi_gpadc_chan_select functions,
>>>  - rename soc_specific struct to gpadc_data,
>>>  - rename soc_specific field to data in sun4i_gpadc_dev,
>>>  - return error code from regmap_write in case of failure in read_raws,
>>>  - share if condition in IIO_CHAN_INFO_RAW case,
>>>  - add comment on why we use parent device for registering in thermal,
>>>  - reordering remove function,
>>>
>>> v4:
>>>  - rename files and variables from sunxi* to sun4i*,
>>>  - shorten sunxi_gpadc_soc_specific structure to soc_specific,
>>>  - factorize sysfs ADC and temp read_raws,
>>>  - use cached values when read_raw times out (except before a first value
>>>    is gotten),
>>>  - remove mutex locks and unlocks from runtime_pm functions,
>>>  - factorize irq initializations,
>>>  - initialize temp_data and fifo_data values to -1 (error value),
>>>  - "impersonate" MFD to register in thermal framework,
>>>  - deactivate hardware interrupts one by one when probe fails or when
>>>    removing driver instead of blindly deactivating all hardware interrupts,
>>>  - selects THERMAL_OF in Kconfig,
>>>
>>> v3:
>>>  - correct wrapping,
>>>  - add comment about thermal sensor inner working,
>>>  - move defines in mfd header,
>>>  - use structure to define SoC specific registers or behaviour,
>>>  - attach this structure to the device according to of_device_id of the
>>>    platform device,
>>>  - use new mutex instead of iio_dev mutex,
>>>  - use atomic flags to avoid race between request_irq and disable_irq in
>>>    probe,
>>>  - switch from processed value to raw, offset and scale values for
>>>    temperature ADC channel,
>>>  - remove faulty sentinel in iio_chan_spec array,
>>>  - add pm_runtime support,
>>>  - register thermal sensor in thermal framework (forgotten since the
>>>    beginning whereas it is present in current sun4i-ts driver),
>>>  - remove useless ret variables to store return value of regmap_reads,
>>>  - move comments on thermal sensor acquisition period in code instead of
>>>    header,
>>>  - adding goto label to unregister iio_map_array when failing to register
>>>    iio_dev,
>>>
>>> v2:
>>>  - add SUNXI_GPADC_ prefixes for defines,
>>>  - correct typo in Kconfig,
>>>  - reorder alphabetically includes, makefile,
>>>  - add license header,
>>>  - fix architecture variations not being handled in interrupt handlers or
>>>    read raw functions,
>>>  - fix unability to return negative values from thermal sensor,
>>>  - add gotos to reduce code repetition,
>>>  - fix irq variable being unsigned int instead of int,
>>>  - remove useless dev_err and dev_info,
>>>  - deactivate all interrupts if probe fails,
>>>  - fix iio_device_register on NULL variable,
>>>  - deactivate ADC in the IP when probe fails or when removing driver,
>>>
>>>  drivers/iio/adc/Kconfig           |  13 +
>>>  drivers/iio/adc/Makefile          |   1 +
>>>  drivers/iio/adc/sun4i-gpadc-iio.c | 522 ++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 536 insertions(+)
>>>  create mode 100644 drivers/iio/adc/sun4i-gpadc-iio.c
>>>
>>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>>> index 25378c5..ea36a4f 100644
>>> --- a/drivers/iio/adc/Kconfig
>>> +++ b/drivers/iio/adc/Kconfig
>>> @@ -384,6 +384,19 @@ config ROCKCHIP_SARADC
>>>  	  To compile this driver as a module, choose M here: the
>>>  	  module will be called rockchip_saradc.
>>>  
>>> +config SUN4I_GPADC
>>> +	tristate "Support for the Allwinner SoCs GPADC"
>>> +	depends on IIO
>>> +	depends on MFD_SUN4I_GPADC
>>> +	select THERMAL_OF
>>> +	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.
>>> +
>>> +	  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
>>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
>>> index 38638d4..204372d 100644
>>> --- a/drivers/iio/adc/Makefile
>>> +++ b/drivers/iio/adc/Makefile
>>> @@ -37,6 +37,7 @@ obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
>>>  obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
>>>  obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
>>>  obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
>>> +obj-$(CONFIG_SUN4I_GPADC) += sun4i-gpadc-iio.o
>>>  obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
>>>  obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
>>>  obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
>>> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
>>> new file mode 100644
>>> index 0000000..e2c5ba8
>>> --- /dev/null
>>> +++ b/drivers/iio/adc/sun4i-gpadc-iio.c
>>> @@ -0,0 +1,522 @@
>>> +/* ADC driver for sunxi platforms' (A10, A13 and A31) GPADC
>>> + *
>>> + * Copyright (c) 2016 Quentin Schulz <quentin.schulz@...e-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/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);
>>> +};
>>> +
>>> +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,
>>> +};
>>> +
>>> +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,
>>> +};
>>> +
>>> +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,
>>> +};
>>> +
>>> +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),		\
>>> +	.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 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 = 0;
>>> +
>>> +	pm_runtime_get_sync(indio_dev->dev.parent);
>>> +	mutex_lock(&info->mutex);
>>> +
>>> +	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;
>>> +
>>> +	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));
>>> +	} 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;
>>> +
>>> +	enable_irq(irq);
>>> +
>>> +	if (!wait_for_completion_timeout(&info->completion,
>>> +					 msecs_to_jiffies(100))) {
>>> +		if ((irq == info->fifo_data_irq && info->adc_data == -1) ||
>>> +		    (irq == info->temp_data_irq && info->temp_data == -1)) {
>>> +			ret = -ETIMEDOUT;
>>> +			goto out;
>>> +		}
>>> +	}
>>> +
>>> +	if (irq == info->fifo_data_irq)
>>> +		*val = info->adc_data;
>>> +	else
>>> +		*val = info->temp_data;
>>> +
>>> +	ret = 0;
>>> +
>>> +out:
>>> +	disable_irq(irq);
>>> +	mutex_unlock(&info->mutex);
>>> +	pm_runtime_mark_last_busy(indio_dev->dev.parent);
>>> +	pm_runtime_put_autosuspend(indio_dev->dev.parent);
>>> +
>>> +	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:
>>> +		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))
>>> +		return IRQ_HANDLED;
>>> +
>>> +	if (!regmap_read(info->regmap, SUN4I_GPADC_TEMP_DATA, &info->temp_data))
>>> +		complete(&info->completion);
>>> +
>>> +	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))
>>> +		return IRQ_HANDLED;
>>> +
>>> +	if (!regmap_read(info->regmap, SUN4I_GPADC_DATA, &info->adc_data))
>>> +		complete(&info->completion);
>>> +
>>> +	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; ~1.3s */
>>> +	regmap_write(info->regmap, SUN4I_GPADC_TPR,
>>> +		     SUN4I_GPADC_TPR_TEMP_ENABLE |
>>> +		     SUN4I_GPADC_TPR_TEMP_PERIOD(1953));
>>> +
>>> +	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 reading temperature times out, take stored previous value. */
>>> +	if (sun4i_gpadc_temp_read(info->indio_dev, &val))
>>> +		val = info->temp_data;
>>> +	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);
>>> +
>>> +	*irq = platform_get_irq_byname(pdev, name);
>>> +	if (*irq < 0) {
>>> +		dev_err(&pdev->dev, "no %s interrupt registered\n", name);
>>> +		return *irq;
>>> +	}
>>> +
>>> +	*irq = regmap_irq_get_virq(mfd_dev->regmap_irqc, *irq);
>>> +	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;
>>> +	struct thermal_zone_device *tzd;
>>> +
>>> +	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;
>>> +	info->temp_data = -1;
>>> +	info->adc_data = -1;
>>> +	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;
>>> +
>>> +	/*
>>> +	 * This driver is a child of an MFD which has a node in the DT but not
>>> +	 * its children. 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.
>>> +	 */
>>> +	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));
>>> +		return PTR_ERR(tzd);
>>> +	}
>>> +
>>> +	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);
>>> +
>>> +	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;
>>> +
>>> +	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 = iio_device_register(indio_dev);
>>> +	if (ret < 0) {
>>> +		dev_err(&pdev->dev, "could not register the device\n");
>>> +		goto err_map;
>>> +	}
>>> +
>>> +	return 0;
>>> +
>>> +err_map:
>>> +	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 sun4i_gpadc_iio *info;
>>> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>>> +
>>> +	pm_runtime_put(&pdev->dev);
>>> +	pm_runtime_disable(&pdev->dev);
>>> +	info = iio_priv(indio_dev);
>>> +	iio_map_array_unregister(indio_dev);
>>> +	iio_device_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@...e-electrons.com>");
>>> +MODULE_LICENSE("GPL v2");
>>>
>>
> 

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