Message-ID: <20180622151338.00003622@huawei.com>
Date:   Fri, 22 Jun 2018 15:13:38 +0100
From:   Jonathan Cameron <jonathan.cameron@...wei.com>
To:     Baolin Wang <baolin.wang@...aro.org>
CC:     <jic23@...nel.org>, <robh+dt@...nel.org>, <mark.rutland@....com>,
        <knaack.h@....de>, <lars@...afoo.de>, <pmeerw@...erw.net>,
        <freeman.liu@...eadtrum.com>, <broonie@...nel.org>,
        <devicetree@...r.kernel.org>, <linux-iio@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] iio: adc: Add Spreadtrum SC27XX PMICs ADC
 support

On Thu, 21 Jun 2018 11:14:05 +0800
Baolin Wang <baolin.wang@...aro.org> wrote:

> From: Freeman Liu <freeman.liu@...eadtrum.com>
> 
> The Spreadtrum SC27XX PMICs ADC controller contains 32 channels,
> which is used to sample voltages with 12 bits conversion.
> 
> [Baolin Wang did lots of improvements]
> 
> Signed-off-by: Freeman Liu <freeman.liu@...eadtrum.com>
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>

One trivial missed bit of cleanup inline.  I'll sort that
when applying if no one else points anything out before I get back to my
development machine.

Jonathan

> ---
> Changes since v2:
>  - Remove lock when read/set the channel scale.
>  - Add devm actions to fix race issue.
>  - Drop the device data and will be added in future if it needed.
>  - Undo the previous operation if enabling ADC failed.
>  - Remove raw access.
>  - Fix some coding style issues.
> 
> Changes since v1:
>  - Add const for static structures definition.
>  - Change SC27XX_ADC_TO_VOLTAGE macro to be one function.
>  - Move channel scale accessing into mutex protection.
>  - Fix some typos.
> ---
>  drivers/iio/adc/Kconfig      |   10 +
>  drivers/iio/adc/Makefile     |    1 +
>  drivers/iio/adc/sc27xx_adc.c |  526 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 537 insertions(+)
>  create mode 100644 drivers/iio/adc/sc27xx_adc.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 9da7907..985b73e 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -621,6 +621,16 @@ config ROCKCHIP_SARADC
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called rockchip_saradc.
>  
> +config SC27XX_ADC
> +	tristate "Spreadtrum SC27xx series PMICs ADC"
> +	depends on MFD_SC27XX_PMIC || COMPILE_TEST
> +	help
> +	  Say yes here to build support for the integrated ADC inside the
> +	  Spreadtrum SC27xx series PMICs.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called sc27xx_adc.
> +
>  config SPEAR_ADC
>  	tristate "ST SPEAr ADC"
>  	depends on PLAT_SPEAR || COMPILE_TEST
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 28a9423..03db7b5 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -59,6 +59,7 @@ obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
>  obj-$(CONFIG_QCOM_PM8XXX_XOADC) += qcom-pm8xxx-xoadc.o
>  obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
>  obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
> +obj-$(CONFIG_SC27XX_ADC) += sc27xx_adc.o
>  obj-$(CONFIG_SPEAR_ADC) += spear_adc.o
>  obj-$(CONFIG_STX104) += stx104.o
>  obj-$(CONFIG_SUN4I_GPADC) += sun4i-gpadc-iio.o
> diff --git a/drivers/iio/adc/sc27xx_adc.c b/drivers/iio/adc/sc27xx_adc.c
> new file mode 100644
> index 0000000..58bc73b
> --- /dev/null
> +++ b/drivers/iio/adc/sc27xx_adc.c
> @@ -0,0 +1,526 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2018 Spreadtrum Communications Inc.
> +
> +#include <linux/hwspinlock.h>
> +#include <linux/iio/iio.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +/* PMIC global registers definition */
> +#define SC27XX_MODULE_EN		0xc08
> +#define SC27XX_MODULE_ADC_EN		BIT(5)
> +#define SC27XX_ARM_CLK_EN		0xc10
> +#define SC27XX_CLK_ADC_EN		BIT(5)
> +#define SC27XX_CLK_ADC_CLK_EN		BIT(6)
> +
> +/* ADC controller registers definition */
> +#define SC27XX_ADC_CTL			0x0
> +#define SC27XX_ADC_CH_CFG		0x4
> +#define SC27XX_ADC_DATA			0x4c
> +#define SC27XX_ADC_INT_EN		0x50
> +#define SC27XX_ADC_INT_CLR		0x54
> +#define SC27XX_ADC_INT_STS		0x58
> +#define SC27XX_ADC_INT_RAW		0x5c
> +
> +/* Bits and mask definition for SC27XX_ADC_CTL register */
> +#define SC27XX_ADC_EN			BIT(0)
> +#define SC27XX_ADC_CHN_RUN		BIT(1)
> +#define SC27XX_ADC_12BIT_MODE		BIT(2)
> +#define SC27XX_ADC_RUN_NUM_MASK		GENMASK(7, 4)
> +#define SC27XX_ADC_RUN_NUM_SHIFT	4
> +
> +/* Bits and mask definition for SC27XX_ADC_CH_CFG register */
> +#define SC27XX_ADC_CHN_ID_MASK		GENMASK(4, 0)
> +#define SC27XX_ADC_SCALE_MASK		GENMASK(10, 8)
> +#define SC27XX_ADC_SCALE_SHIFT		8
> +
> +/* Bits definitions for SC27XX_ADC_INT_EN registers */
> +#define SC27XX_ADC_IRQ_EN		BIT(0)
> +
> +/* Bits definitions for SC27XX_ADC_INT_CLR registers */
> +#define SC27XX_ADC_IRQ_CLR		BIT(0)
> +
> +/* Mask definition for SC27XX_ADC_DATA register */
> +#define SC27XX_ADC_DATA_MASK		GENMASK(11, 0)
> +
> +/* Timeout (ms) for the trylock of hardware spinlocks */
> +#define SC27XX_ADC_HWLOCK_TIMEOUT	5000
> +
> +/* Maximum ADC channel number */
> +#define SC27XX_ADC_CHANNEL_MAX		32
> +
> +/* ADC voltage ratio definition */
> +#define SC27XX_VOLT_RATIO(n, d)		\
> +	(((n) << SC27XX_RATIO_NUMERATOR_OFFSET) | (d))
> +#define SC27XX_RATIO_NUMERATOR_OFFSET	16
> +#define SC27XX_RATIO_DENOMINATOR_MASK	GENMASK(15, 0)
> +
> +struct sc27xx_adc_data {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	/*
> +	 * One hardware spinlock to synchronize between the multiple
> +	 * subsystems which will access the unique ADC controller.
> +	 */
> +	struct hwspinlock *hwlock;
> +	struct completion completion;
> +	int channel_scale[SC27XX_ADC_CHANNEL_MAX];
> +	u32 base;
> +	int value;
> +	int irq;
> +};
> +
> +struct sc27xx_adc_linear_graph {
> +	int volt0;
> +	int adc0;
> +	int volt1;
> +	int adc1;
> +};
> +
> +/*
> + * According to the datasheet, we can convert one ADC value to one voltage value
> + * through 2 points in the linear graph. If the voltage is less than 1.2v, we
> + * should use the small-scale graph, and if more than 1.2v, we should use the
> + * big-scale graph.
> + */
> +static const struct sc27xx_adc_linear_graph big_scale_graph = {
> +	4200, 3310,
> +	3600, 2832,
> +};
> +
> +static const struct sc27xx_adc_linear_graph small_scale_graph = {
> +	1000, 3413,
> +	100, 341,
> +};
> +
> +static int sc27xx_adc_get_ratio(int channel, int scale)
> +{
> +	switch (channel) {
> +	case 1:
> +	case 2:
> +	case 3:
> +	case 4:
> +		return scale ? SC27XX_VOLT_RATIO(400, 1025) :
> +			SC27XX_VOLT_RATIO(1, 1);
> +	case 5:
> +		return SC27XX_VOLT_RATIO(7, 29);
> +	case 6:
> +		return SC27XX_VOLT_RATIO(375, 9000);
> +	case 7:
> +	case 8:
> +		return scale ? SC27XX_VOLT_RATIO(100, 125) :
> +			SC27XX_VOLT_RATIO(1, 1);
> +	case 19:
> +		return SC27XX_VOLT_RATIO(1, 3);
> +	default:
> +		return SC27XX_VOLT_RATIO(1, 1);
> +	}
> +	return SC27XX_VOLT_RATIO(1, 1);
> +}
> +
> +static int sc27xx_adc_read(struct sc27xx_adc_data *data, int channel,
> +			   int scale, int *val)
> +{
> +	int ret;
> +	u32 tmp;
> +
> +	reinit_completion(&data->completion);
> +
> +	ret = hwspin_lock_timeout_raw(data->hwlock, SC27XX_ADC_HWLOCK_TIMEOUT);
> +	if (ret) {
> +		dev_err(data->dev, "timeout to get the hwspinlock\n");
> +		return ret;
> +	}
> +
> +	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
> +				 SC27XX_ADC_EN, SC27XX_ADC_EN);
> +	if (ret)
> +		goto unlock_adc;
> +
> +	/* Configure the channel id and scale */
> +	tmp = (scale << SC27XX_ADC_SCALE_SHIFT) & SC27XX_ADC_SCALE_MASK;
> +	tmp |= channel & SC27XX_ADC_CHN_ID_MASK;
> +	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CH_CFG,
> +				 SC27XX_ADC_CHN_ID_MASK | SC27XX_ADC_SCALE_MASK,
> +				 tmp);
> +	if (ret)
> +		goto disable_adc;
> +
> +	/* Select 12bit conversion mode, and only sample 1 time */
> +	tmp = SC27XX_ADC_12BIT_MODE;
> +	tmp |= (0 << SC27XX_ADC_RUN_NUM_SHIFT) & SC27XX_ADC_RUN_NUM_MASK;
> +	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
> +				 SC27XX_ADC_RUN_NUM_MASK | SC27XX_ADC_12BIT_MODE,
> +				 tmp);
> +	if (ret)
> +		goto disable_adc;
> +
> +	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
> +				 SC27XX_ADC_CHN_RUN, SC27XX_ADC_CHN_RUN);
> +	if (ret)
> +		goto disable_adc;
> +
> +	wait_for_completion(&data->completion);
> +
> +disable_adc:
> +	regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
> +			   SC27XX_ADC_EN, 0);
> +unlock_adc:
> +	hwspin_unlock_raw(data->hwlock);
> +
> +	if (!ret)
> +		*val = data->value;
> +
> +	return ret;
> +}
> +
> +static irqreturn_t sc27xx_adc_isr(int irq, void *dev_id)
> +{
> +	struct sc27xx_adc_data *data = dev_id;
> +	int ret;
> +
> +	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_INT_CLR,
> +				 SC27XX_ADC_IRQ_CLR, SC27XX_ADC_IRQ_CLR);
> +	if (ret)
> +		return IRQ_RETVAL(ret);
> +
> +	ret = regmap_read(data->regmap, data->base + SC27XX_ADC_DATA,
> +			  &data->value);
> +	if (ret)
> +		return IRQ_RETVAL(ret);
> +
> +	data->value &= SC27XX_ADC_DATA_MASK;
> +	complete(&data->completion);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void sc27xx_adc_volt_ratio(struct sc27xx_adc_data *data,
> +				  int channel, int scale,
> +				  u32 *div_numerator, u32 *div_denominator)
> +{
> +	u32 ratio = sc27xx_adc_get_ratio(channel, scale);
> +
> +	*div_numerator = ratio >> SC27XX_RATIO_NUMERATOR_OFFSET;
> +	*div_denominator = ratio & SC27XX_RATIO_DENOMINATOR_MASK;
> +}
> +
> +static int sc27xx_adc_to_volt(const struct sc27xx_adc_linear_graph *graph,
> +			      int raw_adc)
> +{
> +	int tmp;
> +
> +	tmp = (graph->volt0 - graph->volt1) * (raw_adc - graph->adc1);
> +	tmp /= (graph->adc0 - graph->adc1);
> +	tmp += graph->volt1;
> +
> +	return tmp < 0 ? 0 : tmp;
> +}
> +
> +static int sc27xx_adc_convert_volt(struct sc27xx_adc_data *data, int channel,
> +				   int scale, int raw_adc)
> +{
> +	u32 numerator, denominator;
> +	u32 volt;
> +
> +	/*
> +	 * Convert ADC values to voltage values according to the linear graph,
> +	 * and channel 5 and channel 1 has been calibrated, so we can just
> +	 * return the voltage values calculated by the linear graph. But other
> +	 * channels need be calculated to the real voltage values with the
> +	 * voltage ratio.
> +	 */
> +	switch (channel) {
> +	case 5:
> +		return sc27xx_adc_to_volt(&big_scale_graph, raw_adc);
> +
> +	case 1:
> +		return sc27xx_adc_to_volt(&small_scale_graph, raw_adc);
> +
> +	default:
> +		volt = sc27xx_adc_to_volt(&small_scale_graph, raw_adc);
> +		break;
> +	}
> +
> +	sc27xx_adc_volt_ratio(data, channel, scale, &numerator, &denominator);
> +
> +	return (volt * denominator + numerator / 2) / numerator;
> +}
> +
> +static int sc27xx_adc_read_processed(struct sc27xx_adc_data *data,
> +				     int channel, int scale, int *val)
> +{
> +	int ret, raw_adc;
> +
> +	ret = sc27xx_adc_read(data, channel, scale, &raw_adc);
> +	if (ret)
> +		return ret;
> +
> +	*val = sc27xx_adc_convert_volt(data, channel, scale, raw_adc);
> +	return 0;
> +}
> +
> +static int sc27xx_adc_read_raw(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan,
> +			       int *val, int *val2, long mask)
> +{
> +	struct sc27xx_adc_data *data = iio_priv(indio_dev);
> +	int scale = data->channel_scale[chan->channel];
> +	int ret, tmp;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		mutex_lock(&indio_dev->mlock);
> +		ret = sc27xx_adc_read_processed(data, chan->channel, scale,
> +						&tmp);
> +		mutex_unlock(&indio_dev->mlock);
> +
> +		if (ret)
> +			return ret;
> +
> +		*val = tmp;
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = scale;
> +		return IIO_VAL_INT;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int sc27xx_adc_write_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan,
> +				int val, int val2, long mask)
> +{
> +	struct sc27xx_adc_data *data = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		data->channel_scale[chan->channel] = val;
> +		return IIO_VAL_INT;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info sc27xx_info = {
> +	.read_raw = &sc27xx_adc_read_raw,
> +	.write_raw = &sc27xx_adc_write_raw,
> +};
> +
> +#define SC27XX_ADC_CHANNEL(index) {				\
> +	.type = IIO_VOLTAGE,					\
> +	.channel = index,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |	\
> +			      BIT(IIO_CHAN_INFO_SCALE),		\
> +	.datasheet_name = "CH##index",				\
> +	.indexed = 1,						\
> +}
> +
> +static const struct iio_chan_spec sc27xx_channels[] = {
> +	SC27XX_ADC_CHANNEL(0),
> +	SC27XX_ADC_CHANNEL(1),
> +	SC27XX_ADC_CHANNEL(2),
> +	SC27XX_ADC_CHANNEL(3),
> +	SC27XX_ADC_CHANNEL(4),
> +	SC27XX_ADC_CHANNEL(5),
> +	SC27XX_ADC_CHANNEL(6),
> +	SC27XX_ADC_CHANNEL(7),
> +	SC27XX_ADC_CHANNEL(8),
> +	SC27XX_ADC_CHANNEL(9),
> +	SC27XX_ADC_CHANNEL(10),
> +	SC27XX_ADC_CHANNEL(11),
> +	SC27XX_ADC_CHANNEL(12),
> +	SC27XX_ADC_CHANNEL(13),
> +	SC27XX_ADC_CHANNEL(14),
> +	SC27XX_ADC_CHANNEL(15),
> +	SC27XX_ADC_CHANNEL(16),
> +	SC27XX_ADC_CHANNEL(17),
> +	SC27XX_ADC_CHANNEL(18),
> +	SC27XX_ADC_CHANNEL(19),
> +	SC27XX_ADC_CHANNEL(20),
> +	SC27XX_ADC_CHANNEL(21),
> +	SC27XX_ADC_CHANNEL(22),
> +	SC27XX_ADC_CHANNEL(23),
> +	SC27XX_ADC_CHANNEL(24),
> +	SC27XX_ADC_CHANNEL(25),
> +	SC27XX_ADC_CHANNEL(26),
> +	SC27XX_ADC_CHANNEL(27),
> +	SC27XX_ADC_CHANNEL(28),
> +	SC27XX_ADC_CHANNEL(29),
> +	SC27XX_ADC_CHANNEL(30),
> +	SC27XX_ADC_CHANNEL(31),
> +};
> +
> +static int sc27xx_adc_enable(struct sc27xx_adc_data *data)
> +{
> +	int ret;
> +
> +	ret = regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
> +				 SC27XX_MODULE_ADC_EN, SC27XX_MODULE_ADC_EN);
> +	if (ret)
> +		return ret;
> +
> +	/* Enable ADC work clock and controller clock */
> +	ret = regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
> +				 SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN,
> +				 SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN);
> +	if (ret)
> +		goto disable_adc;
> +
> +	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_INT_EN,
> +				 SC27XX_ADC_IRQ_EN, SC27XX_ADC_IRQ_EN);
> +	if (ret)
> +		goto disable_clk;
> +
> +	return 0;
> +
> +disable_clk:
> +	regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
> +			   SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN, 0);
> +disable_adc:
> +	regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
> +			   SC27XX_MODULE_ADC_EN, 0);
> +
> +	return ret;
> +}
> +
> +static void sc27xx_adc_disable(void *_data)
> +{
> +	struct sc27xx_adc_data *data = _data;
> +
> +	regmap_update_bits(data->regmap, data->base + SC27XX_ADC_INT_EN,
> +			   SC27XX_ADC_IRQ_EN, 0);
> +
> +	/* Disable ADC work clock and controller clock */
> +	regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
> +			   SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN, 0);
> +
> +	regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
> +			   SC27XX_MODULE_ADC_EN, 0);
> +}
> +
> +static void sc27xx_adc_free_hwlock(void *_data)
> +{
> +	struct hwspinlock *hwlock = _data;
> +
> +	hwspin_lock_free(hwlock);
> +}
> +
> +static int sc27xx_adc_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct sc27xx_adc_data *sc27xx_data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*sc27xx_data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	sc27xx_data = iio_priv(indio_dev);
> +
> +	sc27xx_data->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!sc27xx_data->regmap) {
> +		dev_err(&pdev->dev, "failed to get ADC regmap\n");
> +		return -ENODEV;
> +	}
> +
> +	ret = of_property_read_u32(np, "reg", &sc27xx_data->base);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to get ADC base address\n");
> +		return ret;
> +	}
> +
> +	sc27xx_data->irq = platform_get_irq(pdev, 0);
> +	if (sc27xx_data->irq < 0) {
> +		dev_err(&pdev->dev, "failed to get ADC irq number\n");
> +		return sc27xx_data->irq;
> +	}
> +
> +	ret = of_hwspin_lock_get_id(np, 0);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed to get hwspinlock id\n");
> +		return ret;
> +	}
> +
> +	sc27xx_data->hwlock = hwspin_lock_request_specific(ret);
> +	if (!sc27xx_data->hwlock) {
> +		dev_err(&pdev->dev, "failed to request hwspinlock\n");
> +		return -ENXIO;
> +	}
> +
> +	ret = devm_add_action(&pdev->dev, sc27xx_adc_free_hwlock,
> +			      sc27xx_data->hwlock);
> +	if (ret) {
> +		sc27xx_adc_free_hwlock(sc27xx_data->hwlock);
> +		dev_err(&pdev->dev, "failed to add hwspinlock action\n");
> +		return ret;
> +	}
> +
> +	init_completion(&sc27xx_data->completion);
> +	sc27xx_data->dev = &pdev->dev;
> +
> +	ret = sc27xx_adc_enable(sc27xx_data);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to enable ADC module\n");
> +		return ret;
> +	}
> +
> +	ret = devm_add_action(&pdev->dev, sc27xx_adc_disable, sc27xx_data);
> +	if (ret) {
> +		sc27xx_adc_disable(sc27xx_data);
> +		dev_err(&pdev->dev, "failed to add ADC disable action\n");
> +		return ret;
> +	}
> +
> +	ret = devm_request_threaded_irq(&pdev->dev, sc27xx_data->irq, NULL,
> +					sc27xx_adc_isr, IRQF_ONESHOT,
> +					pdev->name, sc27xx_data);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to request ADC irq\n");
> +		return ret;
> +	}
> +
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->name = dev_name(&pdev->dev);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &sc27xx_info;
> +	indio_dev->channels = sc27xx_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(sc27xx_channels);
> +	ret = devm_iio_device_register(&pdev->dev, indio_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "could not register iio (ADC)");
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, indio_dev);

Why?  Looks like this is left over from when we had a remove.

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id sc27xx_adc_of_match[] = {
> +	{ .compatible = "sprd,sc2731-adc", },
> +	{ }
> +};
> +
> +static struct platform_driver sc27xx_adc_driver = {
> +	.probe = sc27xx_adc_probe,
> +	.driver = {
> +		.name = "sc27xx-adc",
> +		.of_match_table = sc27xx_adc_of_match,
> +	},
> +};
> +
> +module_platform_driver(sc27xx_adc_driver);
> +
> +MODULE_AUTHOR("Freeman Liu <freeman.liu@...eadtrum.com>");
> +MODULE_DESCRIPTION("Spreadtrum SC27XX ADC Driver");
> +MODULE_LICENSE("GPL v2");

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