Message-ID: <BY1PR03MB138834ECB5A035305AA1536E9AED0@BY1PR03MB1388.namprd03.prod.outlook.com>
Date:	Mon, 14 Dec 2015 02:48:11 +0000
From:	Chen Bough <Haibo.Chen@...escale.com>
To:	Jonathan Cameron <jic23@...nel.org>,
	"knaack.h@....de" <knaack.h@....de>,
	"lars@...afoo.de" <lars@...afoo.de>,
	"pmeerw@...erw.net" <pmeerw@...erw.net>,
	"shawnguo@...nel.org" <shawnguo@...nel.org>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>
CC:	"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v5 1/4] iio: adc: add IMX7D ADC driver support

Hi Jonathan,

Thanks for your careful and patient review!

Best Regards
Haibo Chen


> -----Original Message-----
> From: Jonathan Cameron [mailto:jic23@...nel.org]
> Sent: Sunday, December 13, 2015 1:03 AM
> To: Chen Haibo-B51421; knaack.h@....de; lars@...afoo.de;
> pmeerw@...erw.net; shawnguo@...nel.org; kernel@...gutronix.de
> Cc: linux-iio@...r.kernel.org; devicetree@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v5 1/4] iio: adc: add IMX7D ADC driver support
> 
> On 08/12/15 10:26, 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>
> One significant issue, but as the fix is simple I've made it.
> A few formatting bits and bobs that I've also cleaned up (overly long
> lines).
> If I don't clean them up on merge I have to deal with the little 'fix'
> patches in the coming weeks :) Easier to do it now.
> I left one case where I felt it would hurt readability alone, but fixed
> the others.
> 
> Applied to the togreg branch of iio.git - initially pushed out as testing
> for the autobuilders to play with it.
> 
> Thanks,
> 
> Jonathan
> > ---
> >  drivers/iio/adc/Kconfig     |   9 +
> >  drivers/iio/adc/Makefile    |   1 +
> >  drivers/iio/adc/imx7d_adc.c | 589
> > ++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 599 insertions(+)
> >  create mode 100644 drivers/iio/adc/imx7d_adc.c
> >
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index
> > 7868c74..3493a46 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 ARCH_MXC || COMPILE_TEST
> > +	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..d3511b9
> > --- /dev/null
> > +++ b/drivers/iio/adc/imx7d_adc.c
> > @@ -0,0 +1,589 @@
> > +/*
> > + * 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/clk.h>
> > +#include <linux/completion.h>
> > +#include <linux/err.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regulator/consumer.h>
> > +
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/driver.h>
> > +#include <linux/iio/sysfs.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_REG_ADC_CHANNEL_CFG2_BASE		0x10
> > +#define IMX7D_EACH_CHANNEL_REG_OFFSET		0x20
> > +
> > +#define IMX7D_REG_ADC_CH_CFG1_CHANNEL_EN			(0x1 << 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(x)			((x) << 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_REG_ADC_INT_STATUS_CHANNEL_CONV_TIME_OUT		0xf0000
> > +
> > +#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_ANALOGUE_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_ANALOGUE_CLK_CONFIG(4,
> IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_4),
> > +	IMX7D_ADC_ANALOGUE_CLK_CONFIG(8,
> IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_8),
> > +	IMX7D_ADC_ANALOGUE_CLK_CONFIG(16,
> IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_16),
> > +	IMX7D_ADC_ANALOGUE_CLK_CONFIG(32,
> IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_32),
> > +	IMX7D_ADC_ANALOGUE_CLK_CONFIG(64,
> IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_64),
> > +	IMX7D_ADC_ANALOGUE_CLK_CONFIG(128,
> > +IMX7D_REG_ADC_TIMER_UNIT_PRE_DIV_128),
> > +};
> > +
> > +#define IMX7D_ADC_CHAN(_idx) {					\
> > +	.type = IIO_VOLTAGE,					\
> > +	.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),
> > +	IMX7D_ADC_CHAN(1),
> > +	IMX7D_ADC_CHAN(2),
> > +	IMX7D_ADC_CHAN(3),
> > +	IMX7D_ADC_CHAN(4),
> > +	IMX7D_ADC_CHAN(5),
> > +	IMX7D_ADC_CHAN(6),
> > +	IMX7D_ADC_CHAN(7),
> > +	IMX7D_ADC_CHAN(8),
> > +	IMX7D_ADC_CHAN(9),
> > +	IMX7D_ADC_CHAN(10),
> > +	IMX7D_ADC_CHAN(11),
> > +	IMX7D_ADC_CHAN(12),
> > +	IMX7D_ADC_CHAN(13),
> > +	IMX7D_ADC_CHAN(14),
> > +	IMX7D_ADC_CHAN(15),
> > +};
> > +
> > +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_rate_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 tmp_cfg1;
> > +	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++) {
> > +		tmp_cfg1 = readl(info->regs + i *
> IMX7D_EACH_CHANNEL_REG_OFFSET);
> > +		tmp_cfg1 &= ~IMX7D_REG_ADC_CH_CFG1_CHANNEL_EN;
> > +		writel(tmp_cfg1, info->regs + i *
> IMX7D_EACH_CHANNEL_REG_OFFSET);
> > +	}
> > +
> > +	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_rate_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 |= IMX7D_REG_ADC_CH_CFG1_CHANNEL_SEL(channel);
> > +
> > +	/* read register REG_ADC_CH_A\B\C\D_CFG2, according to the channel
> chosen */
> > +	cfg2 = readl(info->regs + IMX7D_EACH_CHANNEL_REG_OFFSET * channel +
> > +IMX7D_REG_ADC_CHANNEL_CFG2_BASE);
> > +
> > +	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_OFFSET * channel +
> > +IMX7D_REG_ADC_CHANNEL_CFG2_BASE);
> Whilst line length limits are not set in stone it is best to stick to
> them if there is no good reason to not do so.  Here it owuld make no real
> difference.
> > +	writel(cfg1, info->regs + IMX7D_EACH_CHANNEL_REG_OFFSET * 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 tmp;
> > +
> > +	analogue_core_clk = input_clk / info->pre_div_num;
> > +	tmp = (core_time_unit + 1) * 6;
> > +
> > +	return analogue_core_clk / tmp;
> > +}
> > +
> > +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);
> > +		return IIO_VAL_INT;
> > +
> > +	default:
> > +		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);
> > +	}
> > +
> > +	/*
> > +	 * If the channel A/B/C/D conversion timeout, report it and clear
> these
> > +	 * timeout flags.
> > +	 */
> > +	if (status & IMX7D_REG_ADC_INT_STATUS_CHANNEL_CONV_TIME_OUT) {
> > +		pr_err("%s: ADC got conversion time out interrupt: 0x%08x\n",
> > +			dev_name(info->dev), status);
> > +		status &= ~IMX7D_REG_ADC_INT_STATUS_CHANNEL_CONV_TIME_OUT;
> > +		writel(status, 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 || 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 void imx7d_adc_power_down(struct imx7d_adc *info) {
> > +	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); }
> > +
> > +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(*info));
> > +	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, err = %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, err
> = %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = regulator_enable(info->vref);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Can't enable adc reference top voltage,
> err = %d\n", 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->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;
> It's trivial but this goto label naming isn't accurate as the device
> register doesn't occur for a few more lines...
> > +	}
> > +
> > +	imx7d_adc_feature_config(info);
> > +	imx7d_adc_hw_init(info);
> > +
> > +	ret = iio_device_register(indio_dev);
> > +	if (ret) {
> > +		imx7d_adc_power_down(info);
> > +		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);
> > +
> > +	imx7d_adc_power_down(info);
> I might fix this up, but the power down definitely wants to occur 'after'
> you have removed the userspace interface (so after the
> iio_device_unregister call).
> 
> > +
> > +	iio_device_unregister(indio_dev);
> > +	clk_disable_unprepare(info->clk);
> > +	regulator_disable(info->vref);
> > +
> > +	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);
> > +
> > +	imx7d_adc_power_down(info);
> > +
> > +	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) {
> > +		dev_err(info->dev,
> > +			"Can't enable adc reference top voltage, err = %d\n",
> 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 <haibo.chen@...escale.com>");
> > +MODULE_DESCRIPTION("Freeacale IMX7D ADC driver"); MODULE_LICENSE("GPL
> > +v2");
> >

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