Date:	Sat, 14 Nov 2015 17:38:49 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	Haibo Chen <haibo.chen@...escale.com>, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	shawnguo@...nel.org, kernel@...gutronix.de, linux@....linux.org.uk,
	knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net
Cc:	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-iio@...r.kernel.org
Subject: Re: [PATCH v2 1/4] iio: adc: add IMX7D ADC driver support

On 09/11/15 13:28, 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 <haibo.chen@...escale.com>
Hi Haibo,

A few comments inline in addition to Lars' ones.

One small point is that whilst the 80 char limit
should be ignored when obeying it significantly hurts readability, there
are cases in here where it wouldn't hurt to keep the lines shorter, so that
would be preferred.

Mostly looking good.

Jonathan
> ---
>  drivers/iio/adc/Kconfig     |   9 +
>  drivers/iio/adc/Makefile    |   1 +
>  drivers/iio/adc/imx7d_adc.c | 571 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 581 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
> +	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..7e25e4e
> --- /dev/null
> +++ b/drivers/iio/adc/imx7d_adc.c
> @@ -0,0 +1,571 @@
> +/*
> + * 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/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/io.h>
> +#include <linux/clk.h>
> +#include <linux/completion.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/of_platform.h>
> +#include <linux/err.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/driver.h>
> +
> +/* This will be the driver name the kernel reports */
> +#define DRIVER_NAME "imx7d_adc"
It's only used in one place so don't bother with the define.
Use the string inline and it's immediately obvious what it
is for without the comment.

> +
> +/* 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
> +
> +#define IMX7D_REG_ADC_CH_CFG1_CHANNEL_EN			(0x1 << 31)
> +#define IMX7D_REG_ADC_CH_CFG1_CHANNEL_DISABLE			(0x0 << 31)
> +#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 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,
> +};
> +
I'd prefer prefixes on these enum defs e.g.
imx7d_adc_average_num

The naming is generic enough it might bit us in future otherwise!
> +enum 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 clk_pre_div clk_pre_div;
> +	enum 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;
> +}
> +
> +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);
> +
> +	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);
I don't think readability would be hurt by breaking the above line to keep
it shorter.
> +	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);
> +
> +	/* 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) & 0x0f;
> +		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:
> +		*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;
> +
> +	/*
> +	 * 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);
> +	}
> +	writel(0, info->regs + IMX7D_REG_ADC_INT_STATUS);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +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)))
> +		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;
> +	u32 channels;
> +
> +	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;
> +	}
> +
> +	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);
> +		return ret;
> +	}
> +
> +	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;
> +	}
> +
> +	ret = regulator_enable(info->vref);
> +	if (ret)
> +		return ret;
> +
> +	info->vref_uv = regulator_get_voltage(info->vref);
Given the use of this isn't typically on a fast path, I'd be tempted
to query the regulator when you need to know (i.e. in the scale
read).  That avoids the tiny possibility that the regulator voltage
has changed (which would be odd for a reference voltage source!)

> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	init_completion(&info->completion);
> +
> +	ret  = of_property_read_u32(pdev->dev.of_node,
> +					"num-channels", &channels);
> +	if (ret)
> +		channels = ARRAY_SIZE(imx7d_adc_iio_channels);
> +
> +	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 = (int)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;
> +	}
> +
> +	imx7d_adc_feature_config(info);
> +	imx7d_adc_hw_init(info);
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Couldn't register the device.\n");
> +		goto error_iio_device_register;
> +	}
> +
> +	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;
Readability isn't going to be greatly reduced by breaking the line above, so
in this case I'd keep to the 80 char limit.

> +	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	= DRIVER_NAME,
> +		.of_match_table = imx7d_adc_match,
> +		.pm	= &imx7d_adc_pm_ops,
> +	},
> +};
> +
> +module_platform_driver(imx7d_adc_driver);
> +
> +MODULE_AUTHOR("Haibo Chen <haibo.chen@...escale.com>");
> +MODULE_DESCRIPTION("Freeacale IMX7D ADC driver");
> +MODULE_LICENSE("GPL v2");
> 

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