[PATCH v2 1/4] iio: adc: add IMX7D ADC driver support

[Haibo Chen <haibo.chen@freescale.com>]

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@freescale.com>
---
 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"
+
+/* 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,
+};
+
+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);
+	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);
+
+	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;
+	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@freescale.com>");
+MODULE_DESCRIPTION("Freeacale IMX7D ADC driver");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1