Subject: [PATCH v3 1/4] iio: adc: add IMX7D ADC driver support

From: [email-masked] (Jonathan Cameron)
Date: Sun, 29 Nov 2015 15:33:42 +0000

On 25/11/15 03:52, Stefan Agner wrote:
> Hi Haibo,
> 
> Some comments below:
> 
> On 2015-11-20 07:48, Haibo Chen wrote:
>> Freescale i.MX7D soc contains a new ADC IP. This patch add this ADC
>> driver support, and the driver only support ADC software trigger.
>>
>> Signed-off-by: Haibo Chen <[email-masked]>
>> ---
>>  drivers/iio/adc/Kconfig     |   9 +
>>  drivers/iio/adc/Makefile    |   1 +
>>  drivers/iio/adc/imx7d_adc.c | 570 ++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 580 insertions(+)
>>  create mode 100644 drivers/iio/adc/imx7d_adc.c
>>
>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>> index 7868c74..bf0611c 100644
>> --- a/drivers/iio/adc/Kconfig
>> +++ b/drivers/iio/adc/Kconfig
>> @@ -194,6 +194,15 @@ config HI8435
>>  	  This driver can also be built as a module. If so, the module will be
>>  	  called hi8435.
>>  
>> +config IMX7D_ADC
>> +	tristate "IMX7D ADC driver"
>> +	depends on OF
> 
> Hm, not sure, but shouldn't we use a proper depends here? Otherwise this
> will show up as modules in all kinds of distributions.
usual trick is a depends on the platform or COMPILE_TEST
(so that autobuilders will hit it)
> 
>> +	help
>> +	  Say yes here to build support for IMX7D ADC.
>> +
>> +	  This driver can also be built as a module. If so, the module will be
>> +	  called imx7d_adc.
>> +
>>  config LP8788_ADC
>>  	tristate "LP8788 ADC driver"
>>  	depends on MFD_LP8788
>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
>> index 99b37a9..282ffc01 100644
>> --- a/drivers/iio/adc/Makefile
>> +++ b/drivers/iio/adc/Makefile
>> @@ -20,6 +20,7 @@ obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o
>>  obj-$(CONFIG_DA9150_GPADC) += da9150-gpadc.o
>>  obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
>>  obj-$(CONFIG_HI8435) += hi8435.o
>> +obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o
>>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>>  obj-$(CONFIG_MAX1027) += max1027.o
>>  obj-$(CONFIG_MAX1363) += max1363.o
>> diff --git a/drivers/iio/adc/imx7d_adc.c b/drivers/iio/adc/imx7d_adc.c
>> new file mode 100644
>> index 0000000..d9547bf
>> --- /dev/null
>> +++ b/drivers/iio/adc/imx7d_adc.c
>> @@ -0,0 +1,570 @@
>> +/*
>> + * Freescale i.MX7D ADC driver
>> + *
>> + * Copyright (C) 2015 Freescale Semiconductor, Inc.
>> + *
>> + * 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; either version 2 of the License, or
>> + * (at your option) any later version.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/kernel.h>
>> +#include <linux/clk.h>
>> +#include <linux/completion.h>
>> +#include <linux/io.h>
>> +#include <linux/of.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/err.h>
> 
> Can you sort these alphabetically
> 
>> +
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/sysfs.h>
>> +#include <linux/iio/driver.h>
>> +
>> +/* ADC register */
>> +#define IMX7D_REG_ADC_CH_A_CFG1			0x00
>> +#define IMX7D_REG_ADC_CH_A_CFG2			0x10
>> +#define IMX7D_REG_ADC_CH_B_CFG1			0x20
>> +#define IMX7D_REG_ADC_CH_B_CFG2			0x30
>> +#define IMX7D_REG_ADC_CH_C_CFG1			0x40
>> +#define IMX7D_REG_ADC_CH_C_CFG2			0x50
>> +#define IMX7D_REG_ADC_CH_D_CFG1			0x60
>> +#define IMX7D_REG_ADC_CH_D_CFG2			0x70
>> +#define IMX7D_REG_ADC_CH_SW_CFG			0x80
>> +#define IMX7D_REG_ADC_TIMER_UNIT		0x90
>> +#define IMX7D_REG_ADC_DMA_FIFO			0xa0
>> +#define IMX7D_REG_ADC_FIFO_STATUS		0xb0
>> +#define IMX7D_REG_ADC_INT_SIG_EN		0xc0
>> +#define IMX7D_REG_ADC_INT_EN			0xd0
>> +#define IMX7D_REG_ADC_INT_STATUS		0xe0
>> +#define IMX7D_REG_ADC_CHA_B_CNV_RSLT		0xf0
>> +#define IMX7D_REG_ADC_CHC_D_CNV_RSLT		0x100
>> +#define IMX7D_REG_ADC_CH_SW_CNV_RSLT		0x110
>> +#define IMX7D_REG_ADC_DMA_FIFO_DAT		0x120
>> +#define IMX7D_REG_ADC_ADC_CFG			0x130
>> +
>> +#define IMX7D_EACH_CHANNEL_REG_SHIF		0x20
> 
> I would call that OFFSET, SHIFT is typically used for a bit offset
> within a register.
> 
>> +
>> +#define IMX7D_REG_ADC_CH_CFG1_CHANNEL_EN			(0x1 << 31)
>> +#define IMX7D_REG_ADC_CH_CFG1_CHANNEL_DISABLE			(0x0 << 31)
> 
> I would just define the _EN definition (along with using BIT).
> Bitshifting a 0 is not really useful.
> 
>> +#define IMX7D_REG_ADC_CH_CFG1_CHANNEL_SINGLE			BIT(30)
>> +#define IMX7D_REG_ADC_CH_CFG1_CHANNEL_AVG_EN			BIT(29)
>> +#define IMX7D_REG_ADC_CH_CFG1_CHANNEL_SEL_SHIF			24
>> +
>> +#define IMX7D_REG_ADC_CH_CFG2_AVG_NUM_4				(0x0 << 12)
>> +#define IMX7D_REG_ADC_CH_CFG2_AVG_NUM_8				(0x1 << 12)
>> +#define IMX7D_REG_ADC_CH_CFG2_AVG_NUM_16			(0x2 << 12)
>> +#define IMX7D_REG_ADC_CH_CFG2_AVG_NUM_32			(0x3 << 12)
>> +
>> +#define IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_4			(0x0 << 29)
>> +#define IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_8			(0x1 << 29)
>> +#define IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_16			(0x2 << 29)
>> +#define IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_32			(0x3 << 29)
>> +#define IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_64			(0x4 << 29)
>> +#define IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_128			(0x5 << 29)
>> +
>> +#define IMX7D_REG_ADC_ADC_CFG_ADC_CLK_DOWN			BIT(31)
>> +#define IMX7D_REG_ADC_ADC_CFG_ADC_POWER_DOWN			BIT(1)
>> +#define IMX7D_REG_ADC_ADC_CFG_ADC_EN				BIT(0)
>> +
>> +#define IMX7D_REG_ADC_INT_CHA_COV_INT_EN			BIT(8)
>> +#define IMX7D_REG_ADC_INT_CHB_COV_INT_EN			BIT(9)
>> +#define IMX7D_REG_ADC_INT_CHC_COV_INT_EN			BIT(10)
>> +#define IMX7D_REG_ADC_INT_CHD_COV_INT_EN			BIT(11)
>> +#define IMX7D_REG_ADC_INT_CHANNEL_INT_EN			(IMX7D_REG_ADC_INT_CHA_COV_INT_EN | \
>> +								 IMX7D_REG_ADC_INT_CHB_COV_INT_EN | \
>> +								 IMX7D_REG_ADC_INT_CHC_COV_INT_EN | \
>> +								 IMX7D_REG_ADC_INT_CHD_COV_INT_EN)
>> +#define IMX7D_REG_ADC_INT_STATUS_CHANNEL_INT_STATUS		0xf00
>> +
>> +#define IMX7D_ADC_TIMEOUT		msecs_to_jiffies(100)
>> +
>> +enum imx7d_adc_clk_pre_div {
>> +	IMX7D_ADC_ANALOG_CLK_PRE_DIV_4,
>> +	IMX7D_ADC_ANALOG_CLK_PRE_DIV_8,
>> +	IMX7D_ADC_ANALOG_CLK_PRE_DIV_16,
>> +	IMX7D_ADC_ANALOG_CLK_PRE_DIV_32,
>> +	IMX7D_ADC_ANALOG_CLK_PRE_DIV_64,
>> +	IMX7D_ADC_ANALOG_CLK_PRE_DIV_128,
>> +};
>> +
>> +enum imx7d_adc_average_num {
>> +	IMX7D_ADC_AVERAGE_NUM_4,
>> +	IMX7D_ADC_AVERAGE_NUM_8,
>> +	IMX7D_ADC_AVERAGE_NUM_16,
>> +	IMX7D_ADC_AVERAGE_NUM_32,
>> +};
>> +
>> +struct imx7d_adc_feature {
>> +	enum imx7d_adc_clk_pre_div clk_pre_div;
>> +	enum imx7d_adc_average_num avg_num;
>> +
>> +	u32 core_time_unit;	/* impact the sample rate */
>> +
>> +	bool average_en;
>> +};
>> +
>> +struct imx7d_adc {
>> +	struct device *dev;
>> +	void __iomem *regs;
>> +	struct clk *clk;
>> +
>> +	u32 vref_uv;
>> +	u32 value;
>> +	u32 channel;
>> +	u32 pre_div_num;
>> +
>> +	struct regulator *vref;
>> +	struct imx7d_adc_feature adc_feature;
>> +
>> +	struct completion completion;
>> +};
>> +
>> +struct imx7d_adc_analogue_core_clk {
>> +	u32 pre_div;
>> +	u32 reg_config;
>> +};
>> +
>> +#define IMX7D_ADC_ALALOGUE_CLK_CONFIG(_pre_div, _reg_conf) {	\
>> +	.pre_div = (_pre_div),					\
>> +	.reg_config = (_reg_conf),				\
>> +}
>> +
>> +static const struct imx7d_adc_analogue_core_clk imx7d_adc_analogue_clk[] = {
>> +	IMX7D_ADC_ALALOGUE_CLK_CONFIG(4, IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_4),
>> +	IMX7D_ADC_ALALOGUE_CLK_CONFIG(8, IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_8),
>> +	IMX7D_ADC_ALALOGUE_CLK_CONFIG(16, IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_16),
>> +	IMX7D_ADC_ALALOGUE_CLK_CONFIG(32, IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_32),
>> +	IMX7D_ADC_ALALOGUE_CLK_CONFIG(64, IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_64),
>> +	IMX7D_ADC_ALALOGUE_CLK_CONFIG(128, IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_128),
>> +};
>> +
>> +#define IMX7D_ADC_CHAN(_idx, _chan_type) {			\
>> +	.type = (_chan_type),					\
>> +	.indexed = 1,						\
>> +	.channel = (_idx),					\
>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
>> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |	\
>> +				BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
>> +}
>> +
>> +static const struct iio_chan_spec imx7d_adc_iio_channels[] = {
>> +	IMX7D_ADC_CHAN(0, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(1, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(2, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(3, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(4, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(5, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(6, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(7, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(8, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(9, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(10, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(11, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(12, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(13, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(14, IIO_VOLTAGE),
>> +	IMX7D_ADC_CHAN(15, IIO_VOLTAGE),
>> +};
>> +
>> +static const u32 imx7d_adc_average_num[] = {
>> +	IMX7D_REG_ADC_CH_CFG2_AVG_NUM_4,
>> +	IMX7D_REG_ADC_CH_CFG2_AVG_NUM_8,
>> +	IMX7D_REG_ADC_CH_CFG2_AVG_NUM_16,
>> +	IMX7D_REG_ADC_CH_CFG2_AVG_NUM_32,
>> +};
>> +
>> +static void imx7d_adc_feature_config(struct imx7d_adc *info)
>> +{
>> +	info->adc_feature.clk_pre_div = IMX7D_ADC_ANALOG_CLK_PRE_DIV_4;
>> +	info->adc_feature.avg_num = IMX7D_ADC_AVERAGE_NUM_32;
>> +	info->adc_feature.core_time_unit = 1;
>> +	info->adc_feature.average_en = true;
> 
> Since this function is about ADC features, I would pass in a pointer to
> adc_feature. Gets rid of info-> on each line.
> 
>> +}
>> +
>> +static void imx7d_adc_sample_set(struct imx7d_adc *info)
>> +{
>> +	struct imx7d_adc_feature *adc_feature = &info->adc_feature;
>> +	struct imx7d_adc_analogue_core_clk adc_analogure_clk;
>> +	u32 i;
>> +	u32 sample_rate = 0;
>> +
>> +	/*
>> +	 * Before sample set, disable channel A,B,C,D. Here we
>> +	 * clear the bit 31 of register REG_ADC_CH_A\B\C\D_CFG1.
>> +	 */
>> +	for (i = 0; i < 4; i++)
>> +		writel(IMX7D_REG_ADC_CH_CFG1_CHANNEL_DISABLE,
>> +			info->regs + i * IMX7D_EACH_CHANNEL_REG_SHIF);
> 
> This does not clear bit 31 only, but all bits. You need to read into
> tmp, and clear the single bit using ~IMX7D_REG_ADC_CH_CFG1_CHANNEL_EN...
> 
> What I would consider is using regmap. It would allow to use helpers
> such as regmap_update_bits...
> 
>> +
>> +	adc_analogure_clk = imx7d_adc_analogue_clk[adc_feature->clk_pre_div];
>> +	sample_rate |= adc_analogure_clk.reg_config;
>> +	info->pre_div_num = adc_analogure_clk.pre_div;
>> +
>> +	sample_rate |= adc_feature->core_time_unit;
>> +	writel(sample_rate, info->regs + IMX7D_REG_ADC_TIMER_UNIT);
>> +}
>> +
>> +static void imx7d_adc_hw_init(struct imx7d_adc *info)
>> +{
>> +	u32 cfg;
>> +	/* power up and enable adc analogue core */
>> +	cfg = readl(info->regs + IMX7D_REG_ADC_ADC_CFG);
>> +	cfg &= ~(IMX7D_REG_ADC_ADC_CFG_ADC_CLK_DOWN |
>> IMX7D_REG_ADC_ADC_CFG_ADC_POWER_DOWN);
>> +	cfg |= IMX7D_REG_ADC_ADC_CFG_ADC_EN;
>> +	writel(cfg, info->regs + IMX7D_REG_ADC_ADC_CFG);
>> +
>> +	/* enable channel A,B,C,D interrupt */
>> +	writel(IMX7D_REG_ADC_INT_CHANNEL_INT_EN, info->regs +
>> IMX7D_REG_ADC_INT_SIG_EN);
>> +	writel(IMX7D_REG_ADC_INT_CHANNEL_INT_EN, info->regs + IMX7D_REG_ADC_INT_EN);
>> +
>> +	imx7d_adc_sample_set(info);
>> +}
>> +
>> +static void imx7d_adc_channel_set(struct imx7d_adc *info)
>> +{
>> +	u32 cfg1 = 0;
>> +	u32 cfg2;
>> +	u32 channel;
>> +
>> +	channel = info->channel;
>> +
>> +	/* the channel choose single conversion, and enable average mode */
>> +	cfg1 |= (IMX7D_REG_ADC_CH_CFG1_CHANNEL_EN |
>> +		 IMX7D_REG_ADC_CH_CFG1_CHANNEL_SINGLE);
>> +	if (info->adc_feature.average_en)
>> +		cfg1 |= IMX7D_REG_ADC_CH_CFG1_CHANNEL_AVG_EN;
>> +
>> +	/*
>> +	 * physical channel 0 chose logical channel A
>> +	 * physical channel 1 chose logical channel B
>> +	 * physical channel 2 chose logical channel C
>> +	 * physical channel 3 chose logical channel D
>> +	 */
>> +	cfg1 |= (channel << IMX7D_REG_ADC_CH_CFG1_CHANNEL_SEL_SHIF);
> 
> Matter of taste, but I would put the shifting logic into a define above
> and use something like
> IMX7D_REG_ADC_CH_CFG1_CHANNEL_SEL(x)
> 
> 
>> +
>> +	/* read register REG_ADC_CH_A\B\C\D_CFG2, according to the channel chosen */
>> +	cfg2 = readl(info->regs + IMX7D_EACH_CHANNEL_REG_SHIF * channel + 0x10);
>> +
>> +	cfg2 |= imx7d_adc_average_num[info->adc_feature.avg_num];
>> +
>> +	/* write the register REG_ADC_CH_A\B\C\D_CFG2, according to the
>> channel chosen */
>> +	writel(cfg2, info->regs + IMX7D_EACH_CHANNEL_REG_SHIF * channel + 0x10);
>> +	writel(cfg1, info->regs + IMX7D_EACH_CHANNEL_REG_SHIF * channel);
>> +}
>> +
>> +static u32 imx7d_adc_get_sample_rate(struct imx7d_adc *info)
>> +{
>> +	/* input clock is always 24MHz */
>> +	u32 input_clk = 24000000;
>> +	u32 analogue_core_clk;
>> +	u32 core_time_unit = info->adc_feature.core_time_unit;
>> +	u32 sample_clk;
>> +	u32 tmp;
>> +
>> +	analogue_core_clk = input_clk / info->pre_div_num;
>> +	tmp = (core_time_unit + 1) * 6;
>> +	sample_clk = analogue_core_clk / tmp;
>> +
>> +	return sample_clk;
>> +}
>> +
>> +static int imx7d_adc_read_raw(struct iio_dev *indio_dev,
>> +			struct iio_chan_spec const *chan,
>> +			int *val,
>> +			int *val2,
>> +			long mask)
>> +{
>> +	struct imx7d_adc *info = iio_priv(indio_dev);
>> +
>> +	u32 channel;
>> +	long ret;
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW:
>> +		mutex_lock(&indio_dev->mlock);
>> +		reinit_completion(&info->completion);
>> +
>> +		channel = (chan->channel) & 0x03;
>> +		info->channel = channel;
>> +		imx7d_adc_channel_set(info);
>> +
>> +		ret = wait_for_completion_interruptible_timeout
>> +				(&info->completion, IMX7D_ADC_TIMEOUT);
>> +		if (ret == 0) {
>> +			mutex_unlock(&indio_dev->mlock);
>> +			return -ETIMEDOUT;
>> +		}
>> +		if (ret < 0) {
>> +			mutex_unlock(&indio_dev->mlock);
>> +			return ret;
>> +		}
>> +
>> +		*val = info->value;
>> +		mutex_unlock(&indio_dev->mlock);
>> +		return IIO_VAL_INT;
>> +
>> +	case IIO_CHAN_INFO_SCALE:
>> +		info->vref_uv = regulator_get_voltage(info->vref);
>> +		*val = info->vref_uv / 1000;
>> +		*val2 = 12;
>> +		return IIO_VAL_FRACTIONAL_LOG2;
>> +
>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>> +		*val = imx7d_adc_get_sample_rate(info);
>> +		*val2 = 0;
>> +		return IIO_VAL_INT;
>> +
>> +	default:
>> +		break;
>> +	}
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static int imx7d_adc_read_data(struct imx7d_adc *info)
>> +{
>> +	u32 channel;
>> +	u32 value;
>> +
>> +	channel = (info->channel) & 0x03;
>> +
>> +	/*
>> +	 * channel A and B conversion result share one register,
>> +	 * bit[27~16] is the channel B conversion result,
>> +	 * bit[11~0] is the channel A conversion result.
>> +	 * channel C and D is the same.
>> +	 */
>> +	if (channel < 2)
>> +		value = readl(info->regs + IMX7D_REG_ADC_CHA_B_CNV_RSLT);
>> +	else
>> +		value = readl(info->regs + IMX7D_REG_ADC_CHC_D_CNV_RSLT);
>> +	if (channel & 0x1)	/* channel B or D */
>> +		value = (value >> 16) & 0xFFF;
>> +	else			/* channel A or C */
>> +		value &= 0xFFF;
>> +
>> +	return value;
>> +}
>> +
>> +static irqreturn_t imx7d_adc_isr(int irq, void *dev_id)
>> +{
>> +	struct imx7d_adc *info = (struct imx7d_adc *)dev_id;
>> +	int status;
>> +
>> +	status = readl(info->regs + IMX7D_REG_ADC_INT_STATUS);
>> +	if (status & IMX7D_REG_ADC_INT_STATUS_CHANNEL_INT_STATUS) {
>> +		info->value = imx7d_adc_read_data(info);
>> +		complete(&info->completion);
>> +
>> +		/*
>> +		 * The register IMX7D_REG_ADC_INT_STATUS can't clear
>> +		 * itself after read operation, need software to write
>> +		 * 0 to the related bit. Here we clear the channel A/B/C/D
>> +		 * conversion finished flag.
>> +		 */
>> +		status &= ~IMX7D_REG_ADC_INT_STATUS_CHANNEL_INT_STATUS;
>> +		writel(status, info->regs + IMX7D_REG_ADC_INT_STATUS);
>> +		return IRQ_HANDLED;
>> +	}
>> +
>> +	/* For other bits of register IMX7D_REG_ADC_INT_STATUS, ignore them */
>> +	writel(0, info->regs + IMX7D_REG_ADC_INT_STATUS);
>> +	return IRQ_NONE;
>> +}
>> +
>> +static int imx7d_adc_reg_access(struct iio_dev *indio_dev,
>> +			unsigned reg, unsigned writeval,
>> +			unsigned *readval)
>> +{
>> +	struct imx7d_adc *info = iio_priv(indio_dev);
>> +
>> +	if ((readval == NULL) ||
>> +		((reg % 4) || (reg > IMX7D_REG_ADC_ADC_CFG)))
> 
> This looks somewhat hard to read. The parentheses around reg ar
> unnecessary, also you can check for NULL using !.
> 
> if (!readval || reg % 4 || reg > IMX7D_REG_ADC_ADC_CFG)
> ...
> 
>> +		return -EINVAL;
>> +
>> +	*readval = readl(info->regs + reg);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct iio_info imx7d_adc_iio_info = {
>> +	.driver_module = THIS_MODULE,
>> +	.read_raw = &imx7d_adc_read_raw,
>> +	.debugfs_reg_access = &imx7d_adc_reg_access,
>> +};
>> +
>> +static const struct of_device_id imx7d_adc_match[] = {
>> +	{ .compatible = "fsl,imx7d-adc", },
>> +	{ /* sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, imx7d_adc_match);
>> +
>> +static int imx7d_adc_probe(struct platform_device *pdev)
>> +{
>> +	struct imx7d_adc *info;
>> +	struct iio_dev *indio_dev;
>> +	struct resource *mem;
>> +	int irq;
>> +	int ret;
>> +
>> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(struct imx7d_adc));
>> +	if (!indio_dev) {
>> +		dev_err(&pdev->dev, "Failed allocating iio device\n");
>> +		return -ENOMEM;
>> +	}
>> +
>> +	info = iio_priv(indio_dev);
>> +	info->dev = &pdev->dev;
>> +
>> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	info->regs = devm_ioremap_resource(&pdev->dev, mem);
>> +	if (IS_ERR(info->regs)) {
>> +		ret = PTR_ERR(info->regs);
>> +		dev_err(&pdev->dev, "failed to remap adc memory: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	irq = platform_get_irq(pdev, 0);
>> +	if (irq < 0) {
>> +		dev_err(&pdev->dev, "no irq resource?\n");
>> +		return irq;
>> +	}
>> +
>> +	info->clk = devm_clk_get(&pdev->dev, "adc");
>> +	if (IS_ERR(info->clk)) {
>> +		ret = PTR_ERR(info->clk);
>> +		dev_err(&pdev->dev, "failed getting clock, err = %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	info->vref = devm_regulator_get(&pdev->dev, "vref");
>> +	if (IS_ERR(info->vref)) {
>> +		ret = PTR_ERR(info->vref);
>> +		dev_err(&pdev->dev, "failed getting reference voltage: %d\n", ret);
>> +		return ret;
> 
> Use colon or "err =" a bit more consistence across these error messages.
> 
> --
> Stefan
> 
>> +	}
>> +
>> +	ret = regulator_enable(info->vref);
>> +	if (ret)
>> +		return ret;
>> +
>> +	platform_set_drvdata(pdev, 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 = &imx7d_adc_iio_info;
>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>> +	indio_dev->channels = imx7d_adc_iio_channels;
>> +	indio_dev->num_channels = ARRAY_SIZE(imx7d_adc_iio_channels);
>> +
>> +	ret = clk_prepare_enable(info->clk);
>> +	if (ret) {
>> +		dev_err(&pdev->dev,
>> +			"Could not prepare or enable the clock.\n");
>> +		goto error_adc_clk_enable;
>> +	}
>> +
>> +	ret = devm_request_irq(info->dev, irq,
>> +				imx7d_adc_isr, 0,
>> +				dev_name(&pdev->dev), info);
>> +	if (ret < 0) {
>> +		dev_err(&pdev->dev, "failed requesting irq, irq = %d\n", irq);
>> +		goto error_iio_device_register;
>> +	}
>> +
>> +	ret = iio_device_register(indio_dev);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "Couldn't register the device.\n");
>> +		goto error_iio_device_register;
>> +	}
>> +
>> +	imx7d_adc_feature_config(info);
>> +	imx7d_adc_hw_init(info);
>> +
>> +	return 0;
>> +
>> +error_iio_device_register:
>> +	clk_disable_unprepare(info->clk);
>> +error_adc_clk_enable:
>> +	regulator_disable(info->vref);
>> +
>> +	return ret;
>> +}
>> +
>> +static int imx7d_adc_remove(struct platform_device *pdev)
>> +{
>> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>> +	struct imx7d_adc *info = iio_priv(indio_dev);
>> +
>> +	iio_device_unregister(indio_dev);
>> +	regulator_disable(info->vref);
>> +	clk_disable_unprepare(info->clk);
>> +
>> +	return 0;
>> +}
>> +
>> +static int __maybe_unused imx7d_adc_suspend(struct device *dev)
>> +{
>> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>> +	struct imx7d_adc *info = iio_priv(indio_dev);
>> +	u32 adc_cfg;
>> +
>> +	adc_cfg = readl(info->regs + IMX7D_REG_ADC_ADC_CFG);
>> +	adc_cfg |= IMX7D_REG_ADC_ADC_CFG_ADC_CLK_DOWN |
>> +		   IMX7D_REG_ADC_ADC_CFG_ADC_POWER_DOWN;
>> +	adc_cfg &= ~IMX7D_REG_ADC_ADC_CFG_ADC_EN;
>> +	writel(adc_cfg, info->regs + IMX7D_REG_ADC_ADC_CFG);
>> +
>> +	clk_disable_unprepare(info->clk);
>> +	regulator_disable(info->vref);
>> +
>> +	return 0;
>> +}
>> +
>> +static int __maybe_unused imx7d_adc_resume(struct device *dev)
>> +{
>> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>> +	struct imx7d_adc *info = iio_priv(indio_dev);
>> +	int ret;
>> +
>> +	ret = regulator_enable(info->vref);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = clk_prepare_enable(info->clk);
>> +	if (ret) {
>> +		dev_err(info->dev,
>> +			"Could not prepare or enable clock.\n");
>> +		regulator_disable(info->vref);
>> +		return ret;
>> +	}
>> +
>> +	imx7d_adc_hw_init(info);
>> +
>> +	return 0;
>> +}
>> +
>> +static SIMPLE_DEV_PM_OPS(imx7d_adc_pm_ops, imx7d_adc_suspend,
>> imx7d_adc_resume);
>> +
>> +static struct platform_driver imx7d_adc_driver = {
>> +	.probe		= imx7d_adc_probe,
>> +	.remove		= imx7d_adc_remove,
>> +	.driver		= {
>> +		.name	= "imx7d_adc",
>> +		.of_match_table = imx7d_adc_match,
>> +		.pm	= &imx7d_adc_pm_ops,
>> +	},
>> +};
>> +
>> +module_platform_driver(imx7d_adc_driver);
>> +
>> +MODULE_AUTHOR("Haibo Chen <[email-masked]>");
>> +MODULE_DESCRIPTION("Freeacale IMX7D ADC driver");
>> +MODULE_LICENSE("GPL v2");
> --
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