drivers/iio/adc/spear_adc.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * ST SPEAr ADC driver
  *
  * Copyright 2012 Stefan Roese <sr@denx.de>
  */

 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/interrupt.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/io.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/completion.h>
 #include <linux/of.h>
 #include <linux/of_address.h>

 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>

 /* SPEAR registers definitions */
 #define SPEAR600_ADC_SCAN_RATE_LO(x)	((x) & 0xFFFF)
 #define SPEAR600_ADC_SCAN_RATE_HI(x)	(((x) >> 0x10) & 0xFFFF)
 #define SPEAR_ADC_CLK_LOW(x)		(((x) & 0xf) << 0)
 #define SPEAR_ADC_CLK_HIGH(x)		(((x) & 0xf) << 4)

 /* Bit definitions for SPEAR_ADC_STATUS */
 #define SPEAR_ADC_STATUS_START_CONVERSION	BIT(0)
 #define SPEAR_ADC_STATUS_CHANNEL_NUM(x)		((x) << 1)
 #define SPEAR_ADC_STATUS_ADC_ENABLE		BIT(4)
 #define SPEAR_ADC_STATUS_AVG_SAMPLE(x)		((x) << 5)
 #define SPEAR_ADC_STATUS_VREF_INTERNAL		BIT(9)

 #define SPEAR_ADC_DATA_MASK		0x03ff
 #define SPEAR_ADC_DATA_BITS		10

 #define SPEAR_ADC_MOD_NAME "spear-adc"

 #define SPEAR_ADC_CHANNEL_NUM		8

 #define SPEAR_ADC_CLK_MIN			2500000
 #define SPEAR_ADC_CLK_MAX			20000000

 struct adc_regs_spear3xx {
 	u32 status;
 	u32 average;
 	u32 scan_rate;
 	u32 clk;	/* Not avail for 1340 & 1310 */
 	u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
 	u32 ch_data[SPEAR_ADC_CHANNEL_NUM];
 };

 struct chan_data {
 	u32 lsb;
 	u32 msb;
 };

 struct adc_regs_spear6xx {
 	u32 status;
 	u32 pad[2];
 	u32 clk;
 	u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
 	struct chan_data ch_data[SPEAR_ADC_CHANNEL_NUM];
 	u32 scan_rate_lo;
 	u32 scan_rate_hi;
 	struct chan_data average;
 };

 struct spear_adc_state {
 	struct device_node *np;
 	struct adc_regs_spear3xx __iomem *adc_base_spear3xx;
 	struct adc_regs_spear6xx __iomem *adc_base_spear6xx;
 	struct clk *clk;
 	struct completion completion;
 	/*
 	 * Lock to protect the device state during a potential concurrent
 	 * read access from userspace. Reading a raw value requires a sequence
 	 * of register writes, then a wait for a completion callback,
 	 * and finally a register read, during which userspace could issue
 	 * another read request. This lock protects a read access from
 	 * ocurring before another one has finished.
 	 */
 	struct mutex lock;
 	u32 current_clk;
 	u32 sampling_freq;
 	u32 avg_samples;
 	u32 vref_external;
 	u32 value;
 };

 /*
  * Functions to access some SPEAr ADC register. Abstracted into
  * static inline functions, because of different register offsets
  * on different SoC variants (SPEAr300 vs SPEAr600 etc).
  */
 static void spear_adc_set_status(struct spear_adc_state *st, u32 val)
 {
 	__raw_writel(val, &st->adc_base_spear6xx->status);
 }

 static void spear_adc_set_clk(struct spear_adc_state *st, u32 val)
 {
 	u32 clk_high, clk_low, count;
 	u32 apb_clk = clk_get_rate(st->clk);

 	count = DIV_ROUND_UP(apb_clk, val);
 	clk_low = count / 2;
 	clk_high = count - clk_low;
 	st->current_clk = apb_clk / count;

 	__raw_writel(SPEAR_ADC_CLK_LOW(clk_low) | SPEAR_ADC_CLK_HIGH(clk_high),
 		     &st->adc_base_spear6xx->clk);
 }

 static void spear_adc_set_ctrl(struct spear_adc_state *st, int n,
 			       u32 val)
 {
 	__raw_writel(val, &st->adc_base_spear6xx->ch_ctrl[n]);
 }

 static u32 spear_adc_get_average(struct spear_adc_state *st)
 {
 	if (of_device_is_compatible(st->np, "st,spear600-adc")) {
 		return __raw_readl(&st->adc_base_spear6xx->average.msb) &
 			SPEAR_ADC_DATA_MASK;
 	} else {
 		return __raw_readl(&st->adc_base_spear3xx->average) &
 			SPEAR_ADC_DATA_MASK;
 	}
 }

 static void spear_adc_set_scanrate(struct spear_adc_state *st, u32 rate)
 {
 	if (of_device_is_compatible(st->np, "st,spear600-adc")) {
 		__raw_writel(SPEAR600_ADC_SCAN_RATE_LO(rate),
 			     &st->adc_base_spear6xx->scan_rate_lo);
 		__raw_writel(SPEAR600_ADC_SCAN_RATE_HI(rate),
 			     &st->adc_base_spear6xx->scan_rate_hi);
 	} else {
 		__raw_writel(rate, &st->adc_base_spear3xx->scan_rate);
 	}
 }

 static int spear_adc_read_raw(struct iio_dev *indio_dev,
 			      struct iio_chan_spec const *chan,
 			      int *val,
 			      int *val2,
 			      long mask)
 {
 	struct spear_adc_state *st = iio_priv(indio_dev);
 	u32 status;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&st->lock);

 		status = SPEAR_ADC_STATUS_CHANNEL_NUM(chan->channel) |
 			SPEAR_ADC_STATUS_AVG_SAMPLE(st->avg_samples) |
 			SPEAR_ADC_STATUS_START_CONVERSION |
 			SPEAR_ADC_STATUS_ADC_ENABLE;
 		if (st->vref_external == 0)
 			status |= SPEAR_ADC_STATUS_VREF_INTERNAL;

 		spear_adc_set_status(st, status);
 		wait_for_completion(&st->completion); /* set by ISR */
 		*val = st->value;

 		mutex_unlock(&st->lock);

 		return IIO_VAL_INT;

 	case IIO_CHAN_INFO_SCALE:
 		*val = st->vref_external;
 		*val2 = SPEAR_ADC_DATA_BITS;
 		return IIO_VAL_FRACTIONAL_LOG2;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*val = st->current_clk;
 		return IIO_VAL_INT;
 	}

 	return -EINVAL;
 }

 static int spear_adc_write_raw(struct iio_dev *indio_dev,
 			       struct iio_chan_spec const *chan,
 			       int val,
 			       int val2,
 			       long mask)
 {
 	struct spear_adc_state *st = iio_priv(indio_dev);
 	int ret = 0;

 	if (mask != IIO_CHAN_INFO_SAMP_FREQ)
 		return -EINVAL;

 	mutex_lock(&st->lock);

 	if ((val < SPEAR_ADC_CLK_MIN) ||
 	    (val > SPEAR_ADC_CLK_MAX) ||
 	    (val2 != 0)) {
 		ret = -EINVAL;
 		goto out;
 	}

 	spear_adc_set_clk(st, val);

 out:
 	mutex_unlock(&st->lock);
 	return ret;
 }

 #define SPEAR_ADC_CHAN(idx) {				\
 	.type = IIO_VOLTAGE,				\
 	.indexed = 1,					\
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
 	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
 	.channel = idx,					\
 }

 static const struct iio_chan_spec spear_adc_iio_channels[] = {
 	SPEAR_ADC_CHAN(0),
 	SPEAR_ADC_CHAN(1),
 	SPEAR_ADC_CHAN(2),
 	SPEAR_ADC_CHAN(3),
 	SPEAR_ADC_CHAN(4),
 	SPEAR_ADC_CHAN(5),
 	SPEAR_ADC_CHAN(6),
 	SPEAR_ADC_CHAN(7),
 };

 static irqreturn_t spear_adc_isr(int irq, void *dev_id)
 {
 	struct spear_adc_state *st = dev_id;

 	/* Read value to clear IRQ */
 	st->value = spear_adc_get_average(st);
 	complete(&st->completion);

 	return IRQ_HANDLED;
 }

 static int spear_adc_configure(struct spear_adc_state *st)
 {
 	int i;

 	/* Reset ADC core */
 	spear_adc_set_status(st, 0);
 	__raw_writel(0, &st->adc_base_spear6xx->clk);
 	for (i = 0; i < 8; i++)
 		spear_adc_set_ctrl(st, i, 0);
 	spear_adc_set_scanrate(st, 0);

 	spear_adc_set_clk(st, st->sampling_freq);

 	return 0;
 }

 static const struct iio_info spear_adc_info = {
 	.read_raw = &spear_adc_read_raw,
 	.write_raw = &spear_adc_write_raw,
 };

 static int spear_adc_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct device *dev = &pdev->dev;
 	struct spear_adc_state *st;
 	struct iio_dev *indio_dev = NULL;
 	int ret = -ENODEV;
 	int irq;

 	indio_dev = devm_iio_device_alloc(dev, sizeof(struct spear_adc_state));
 	if (!indio_dev) {
 		dev_err(dev, "failed allocating iio device\n");
 		return -ENOMEM;
 	}

 	st = iio_priv(indio_dev);

 	mutex_init(&st->lock);

 	st->np = np;

 	/*
 	 * SPEAr600 has a different register layout than other SPEAr SoC's
 	 * (e.g. SPEAr3xx). Let's provide two register base addresses
 	 * to support multi-arch kernels.
 	 */
 	st->adc_base_spear6xx = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(st->adc_base_spear6xx))
 		return PTR_ERR(st->adc_base_spear6xx);

 	st->adc_base_spear3xx =
 		(struct adc_regs_spear3xx __iomem *)st->adc_base_spear6xx;

 	st->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(st->clk)) {
 		dev_err(dev, "failed getting clock\n");
 		return PTR_ERR(st->clk);
 	}

 	ret = clk_prepare_enable(st->clk);
 	if (ret) {
 		dev_err(dev, "failed enabling clock\n");
 		return ret;
 	}

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		ret = irq;
 		goto errout2;
 	}

 	ret = devm_request_irq(dev, irq, spear_adc_isr, 0, SPEAR_ADC_MOD_NAME,
 			       st);
 	if (ret < 0) {
 		dev_err(dev, "failed requesting interrupt\n");
 		goto errout2;
 	}

 	if (of_property_read_u32(np, "sampling-frequency",
 				 &st->sampling_freq)) {
 		dev_err(dev, "sampling-frequency missing in DT\n");
 		ret = -EINVAL;
 		goto errout2;
 	}

 	/*
 	 * Optional avg_samples defaults to 0, resulting in single data
 	 * conversion
 	 */
 	of_property_read_u32(np, "average-samples", &st->avg_samples);

 	/*
 	 * Optional vref_external defaults to 0, resulting in internal vref
 	 * selection
 	 */
 	of_property_read_u32(np, "vref-external", &st->vref_external);

 	spear_adc_configure(st);

 	platform_set_drvdata(pdev, indio_dev);

 	init_completion(&st->completion);

 	indio_dev->name = SPEAR_ADC_MOD_NAME;
 	indio_dev->info = &spear_adc_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = spear_adc_iio_channels;
 	indio_dev->num_channels = ARRAY_SIZE(spear_adc_iio_channels);

 	ret = iio_device_register(indio_dev);
 	if (ret)
 		goto errout2;

 	dev_info(dev, "SPEAR ADC driver loaded, IRQ %d\n", irq);

 	return 0;

 errout2:
 	clk_disable_unprepare(st->clk);
 	return ret;
 }

 static int spear_adc_remove(struct platform_device *pdev)
 {
 	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 	struct spear_adc_state *st = iio_priv(indio_dev);

 	iio_device_unregister(indio_dev);
 	clk_disable_unprepare(st->clk);

 	return 0;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id spear_adc_dt_ids[] = {
 	{ .compatible = "st,spear600-adc", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, spear_adc_dt_ids);
 #endif

 static struct platform_driver spear_adc_driver = {
 	.probe		= spear_adc_probe,
 	.remove		= spear_adc_remove,
 	.driver		= {
 		.name	= SPEAR_ADC_MOD_NAME,
 		.of_match_table = of_match_ptr(spear_adc_dt_ids),
 	},
 };

 module_platform_driver(spear_adc_driver);

 MODULE_AUTHOR("Stefan Roese <sr@denx.de>");
 MODULE_DESCRIPTION("SPEAr ADC driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* ST SPEAr ADC driver
	*
	* Copyright 2012 Stefan Roese <sr@denx.de>
	*/

	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/interrupt.h>
	#include <linux/device.h>
	#include <linux/kernel.h>
	#include <linux/slab.h>
	#include <linux/io.h>
	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/completion.h>
	#include <linux/of.h>
	#include <linux/of_address.h>

	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>

	/* SPEAR registers definitions */
	#define SPEAR600_ADC_SCAN_RATE_LO(x) ((x) & 0xFFFF)
	#define SPEAR600_ADC_SCAN_RATE_HI(x) (((x) >> 0x10) & 0xFFFF)
	#define SPEAR_ADC_CLK_LOW(x) (((x) & 0xf) << 0)
	#define SPEAR_ADC_CLK_HIGH(x) (((x) & 0xf) << 4)

	/* Bit definitions for SPEAR_ADC_STATUS */
	#define SPEAR_ADC_STATUS_START_CONVERSION BIT(0)
	#define SPEAR_ADC_STATUS_CHANNEL_NUM(x) ((x) << 1)
	#define SPEAR_ADC_STATUS_ADC_ENABLE BIT(4)
	#define SPEAR_ADC_STATUS_AVG_SAMPLE(x) ((x) << 5)
	#define SPEAR_ADC_STATUS_VREF_INTERNAL BIT(9)

	#define SPEAR_ADC_DATA_MASK 0x03ff
	#define SPEAR_ADC_DATA_BITS 10

	#define SPEAR_ADC_MOD_NAME "spear-adc"

	#define SPEAR_ADC_CHANNEL_NUM 8

	#define SPEAR_ADC_CLK_MIN 2500000
	#define SPEAR_ADC_CLK_MAX 20000000

	struct adc_regs_spear3xx {
	u32 status;
	u32 average;
	u32 scan_rate;
	u32 clk; /* Not avail for 1340 & 1310 */
	u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
	u32 ch_data[SPEAR_ADC_CHANNEL_NUM];
	};

	struct chan_data {
	u32 lsb;
	u32 msb;
	};

	struct adc_regs_spear6xx {
	u32 status;
	u32 pad[2];
	u32 clk;
	u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
	struct chan_data ch_data[SPEAR_ADC_CHANNEL_NUM];
	u32 scan_rate_lo;
	u32 scan_rate_hi;
	struct chan_data average;
	};

	struct spear_adc_state {
	struct device_node *np;
	struct adc_regs_spear3xx __iomem *adc_base_spear3xx;
	struct adc_regs_spear6xx __iomem *adc_base_spear6xx;
	struct clk *clk;
	struct completion completion;
	/*
	* Lock to protect the device state during a potential concurrent
	* read access from userspace. Reading a raw value requires a sequence
	* of register writes, then a wait for a completion callback,
	* and finally a register read, during which userspace could issue
	* another read request. This lock protects a read access from
	* ocurring before another one has finished.
	*/
	struct mutex lock;
	u32 current_clk;
	u32 sampling_freq;
	u32 avg_samples;
	u32 vref_external;
	u32 value;
	};

	/*
	* Functions to access some SPEAr ADC register. Abstracted into
	* static inline functions, because of different register offsets
	* on different SoC variants (SPEAr300 vs SPEAr600 etc).
	*/
	static void spear_adc_set_status(struct spear_adc_state *st, u32 val)
	{
	__raw_writel(val, &st->adc_base_spear6xx->status);
	}

	static void spear_adc_set_clk(struct spear_adc_state *st, u32 val)
	{
	u32 clk_high, clk_low, count;
	u32 apb_clk = clk_get_rate(st->clk);

	count = DIV_ROUND_UP(apb_clk, val);
	clk_low = count / 2;
	clk_high = count - clk_low;
	st->current_clk = apb_clk / count;

	__raw_writel(SPEAR_ADC_CLK_LOW(clk_low) \| SPEAR_ADC_CLK_HIGH(clk_high),
	&st->adc_base_spear6xx->clk);
	}

	static void spear_adc_set_ctrl(struct spear_adc_state *st, int n,
	u32 val)
	{
	__raw_writel(val, &st->adc_base_spear6xx->ch_ctrl[n]);
	}

	static u32 spear_adc_get_average(struct spear_adc_state *st)
	{
	if (of_device_is_compatible(st->np, "st,spear600-adc")) {
	return __raw_readl(&st->adc_base_spear6xx->average.msb) &
	SPEAR_ADC_DATA_MASK;
	} else {
	return __raw_readl(&st->adc_base_spear3xx->average) &
	SPEAR_ADC_DATA_MASK;
	}
	}

	static void spear_adc_set_scanrate(struct spear_adc_state *st, u32 rate)
	{
	if (of_device_is_compatible(st->np, "st,spear600-adc")) {
	__raw_writel(SPEAR600_ADC_SCAN_RATE_LO(rate),
	&st->adc_base_spear6xx->scan_rate_lo);
	__raw_writel(SPEAR600_ADC_SCAN_RATE_HI(rate),
	&st->adc_base_spear6xx->scan_rate_hi);
	} else {
	__raw_writel(rate, &st->adc_base_spear3xx->scan_rate);
	}
	}

	static int spear_adc_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int *val,
	int *val2,
	long mask)
	{
	struct spear_adc_state *st = iio_priv(indio_dev);
	u32 status;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	mutex_lock(&st->lock);

	status = SPEAR_ADC_STATUS_CHANNEL_NUM(chan->channel) \|
	SPEAR_ADC_STATUS_AVG_SAMPLE(st->avg_samples) \|
	SPEAR_ADC_STATUS_START_CONVERSION \|
	SPEAR_ADC_STATUS_ADC_ENABLE;
	if (st->vref_external == 0)
	status \|= SPEAR_ADC_STATUS_VREF_INTERNAL;

	spear_adc_set_status(st, status);
	wait_for_completion(&st->completion); /* set by ISR */
	*val = st->value;

	mutex_unlock(&st->lock);

	return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:
	*val = st->vref_external;
	*val2 = SPEAR_ADC_DATA_BITS;
	return IIO_VAL_FRACTIONAL_LOG2;
	case IIO_CHAN_INFO_SAMP_FREQ:
	*val = st->current_clk;
	return IIO_VAL_INT;
	}

	return -EINVAL;
	}

	static int spear_adc_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val,
	int val2,
	long mask)
	{
	struct spear_adc_state *st = iio_priv(indio_dev);
	int ret = 0;

	if (mask != IIO_CHAN_INFO_SAMP_FREQ)
	return -EINVAL;

	mutex_lock(&st->lock);

	if ((val < SPEAR_ADC_CLK_MIN) \|\|
	(val > SPEAR_ADC_CLK_MAX) \|\|
	(val2 != 0)) {
	ret = -EINVAL;
	goto out;
	}

	spear_adc_set_clk(st, val);

	out:
	mutex_unlock(&st->lock);
	return ret;
	}

	#define SPEAR_ADC_CHAN(idx) { \
	.type = IIO_VOLTAGE, \
	.indexed = 1, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
	.channel = idx, \
	}

	static const struct iio_chan_spec spear_adc_iio_channels[] = {
	SPEAR_ADC_CHAN(0),
	SPEAR_ADC_CHAN(1),
	SPEAR_ADC_CHAN(2),
	SPEAR_ADC_CHAN(3),
	SPEAR_ADC_CHAN(4),
	SPEAR_ADC_CHAN(5),
	SPEAR_ADC_CHAN(6),
	SPEAR_ADC_CHAN(7),
	};

	static irqreturn_t spear_adc_isr(int irq, void *dev_id)
	{
	struct spear_adc_state *st = dev_id;

	/* Read value to clear IRQ */
	st->value = spear_adc_get_average(st);
	complete(&st->completion);

	return IRQ_HANDLED;
	}

	static int spear_adc_configure(struct spear_adc_state *st)
	{
	int i;

	/* Reset ADC core */
	spear_adc_set_status(st, 0);
	__raw_writel(0, &st->adc_base_spear6xx->clk);
	for (i = 0; i < 8; i++)
	spear_adc_set_ctrl(st, i, 0);
	spear_adc_set_scanrate(st, 0);

	spear_adc_set_clk(st, st->sampling_freq);

	return 0;
	}

	static const struct iio_info spear_adc_info = {
	.read_raw = &spear_adc_read_raw,
	.write_raw = &spear_adc_write_raw,
	};

	static int spear_adc_probe(struct platform_device *pdev)
	{
	struct device_node *np = pdev->dev.of_node;
	struct device *dev = &pdev->dev;
	struct spear_adc_state *st;
	struct iio_dev *indio_dev = NULL;
	int ret = -ENODEV;
	int irq;

	indio_dev = devm_iio_device_alloc(dev, sizeof(struct spear_adc_state));
	if (!indio_dev) {
	dev_err(dev, "failed allocating iio device\n");
	return -ENOMEM;
	}

	st = iio_priv(indio_dev);

	mutex_init(&st->lock);

	st->np = np;

	/*
	* SPEAr600 has a different register layout than other SPEAr SoC's
	* (e.g. SPEAr3xx). Let's provide two register base addresses
	* to support multi-arch kernels.
	*/
	st->adc_base_spear6xx = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(st->adc_base_spear6xx))
	return PTR_ERR(st->adc_base_spear6xx);

	st->adc_base_spear3xx =
	(struct adc_regs_spear3xx __iomem *)st->adc_base_spear6xx;

	st->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(st->clk)) {
	dev_err(dev, "failed getting clock\n");
	return PTR_ERR(st->clk);
	}

	ret = clk_prepare_enable(st->clk);
	if (ret) {
	dev_err(dev, "failed enabling clock\n");
	return ret;
	}

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	ret = irq;
	goto errout2;
	}

	ret = devm_request_irq(dev, irq, spear_adc_isr, 0, SPEAR_ADC_MOD_NAME,
	st);
	if (ret < 0) {
	dev_err(dev, "failed requesting interrupt\n");
	goto errout2;
	}

	if (of_property_read_u32(np, "sampling-frequency",
	&st->sampling_freq)) {
	dev_err(dev, "sampling-frequency missing in DT\n");
	ret = -EINVAL;
	goto errout2;
	}

	/*
	* Optional avg_samples defaults to 0, resulting in single data
	* conversion
	*/
	of_property_read_u32(np, "average-samples", &st->avg_samples);

	/*
	* Optional vref_external defaults to 0, resulting in internal vref
	* selection
	*/
	of_property_read_u32(np, "vref-external", &st->vref_external);

	spear_adc_configure(st);

	platform_set_drvdata(pdev, indio_dev);

	init_completion(&st->completion);

	indio_dev->name = SPEAR_ADC_MOD_NAME;
	indio_dev->info = &spear_adc_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = spear_adc_iio_channels;
	indio_dev->num_channels = ARRAY_SIZE(spear_adc_iio_channels);

	ret = iio_device_register(indio_dev);
	if (ret)
	goto errout2;

	dev_info(dev, "SPEAR ADC driver loaded, IRQ %d\n", irq);

	return 0;

	errout2:
	clk_disable_unprepare(st->clk);
	return ret;
	}

	static int spear_adc_remove(struct platform_device *pdev)
	{
	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
	struct spear_adc_state *st = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	clk_disable_unprepare(st->clk);

	return 0;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id spear_adc_dt_ids[] = {
	{ .compatible = "st,spear600-adc", },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, spear_adc_dt_ids);
	#endif

	static struct platform_driver spear_adc_driver = {
	.probe = spear_adc_probe,
	.remove = spear_adc_remove,
	.driver = {
	.name = SPEAR_ADC_MOD_NAME,
	.of_match_table = of_match_ptr(spear_adc_dt_ids),
	},
	};

	module_platform_driver(spear_adc_driver);

	MODULE_AUTHOR("Stefan Roese <sr@denx.de>");
	MODULE_DESCRIPTION("SPEAr ADC driver");
	MODULE_LICENSE("GPL");