drivers/iio/adc/sc27xx_adc.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 // Copyright (C) 2018 Spreadtrum Communications Inc.

 #include <linux/hwspinlock.h>
 #include <linux/iio/iio.h>
 #include <linux/module.h>
 #include <linux/nvmem-consumer.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>

 /* PMIC global registers definition */
 #define SC27XX_MODULE_EN		0xc08
 #define SC27XX_MODULE_ADC_EN		BIT(5)
 #define SC27XX_ARM_CLK_EN		0xc10
 #define SC27XX_CLK_ADC_EN		BIT(5)
 #define SC27XX_CLK_ADC_CLK_EN		BIT(6)

 /* ADC controller registers definition */
 #define SC27XX_ADC_CTL			0x0
 #define SC27XX_ADC_CH_CFG		0x4
 #define SC27XX_ADC_DATA			0x4c
 #define SC27XX_ADC_INT_EN		0x50
 #define SC27XX_ADC_INT_CLR		0x54
 #define SC27XX_ADC_INT_STS		0x58
 #define SC27XX_ADC_INT_RAW		0x5c

 /* Bits and mask definition for SC27XX_ADC_CTL register */
 #define SC27XX_ADC_EN			BIT(0)
 #define SC27XX_ADC_CHN_RUN		BIT(1)
 #define SC27XX_ADC_12BIT_MODE		BIT(2)
 #define SC27XX_ADC_RUN_NUM_MASK		GENMASK(7, 4)
 #define SC27XX_ADC_RUN_NUM_SHIFT	4

 /* Bits and mask definition for SC27XX_ADC_CH_CFG register */
 #define SC27XX_ADC_CHN_ID_MASK		GENMASK(4, 0)
 #define SC27XX_ADC_SCALE_MASK		GENMASK(10, 8)
 #define SC27XX_ADC_SCALE_SHIFT		8

 /* Bits definitions for SC27XX_ADC_INT_EN registers */
 #define SC27XX_ADC_IRQ_EN		BIT(0)

 /* Bits definitions for SC27XX_ADC_INT_CLR registers */
 #define SC27XX_ADC_IRQ_CLR		BIT(0)

 /* Bits definitions for SC27XX_ADC_INT_RAW registers */
 #define SC27XX_ADC_IRQ_RAW		BIT(0)

 /* Mask definition for SC27XX_ADC_DATA register */
 #define SC27XX_ADC_DATA_MASK		GENMASK(11, 0)

 /* Timeout (ms) for the trylock of hardware spinlocks */
 #define SC27XX_ADC_HWLOCK_TIMEOUT	5000

 /* Timeout (us) for ADC data conversion according to ADC datasheet */
 #define SC27XX_ADC_RDY_TIMEOUT		1000000
 #define SC27XX_ADC_POLL_RAW_STATUS	500

 /* Maximum ADC channel number */
 #define SC27XX_ADC_CHANNEL_MAX		32

 /* ADC voltage ratio definition */
 #define SC27XX_VOLT_RATIO(n, d)		\
 	(((n) << SC27XX_RATIO_NUMERATOR_OFFSET) | (d))
 #define SC27XX_RATIO_NUMERATOR_OFFSET	16
 #define SC27XX_RATIO_DENOMINATOR_MASK	GENMASK(15, 0)

 struct sc27xx_adc_data {
 	struct device *dev;
 	struct regmap *regmap;
 	/*
 	 * One hardware spinlock to synchronize between the multiple
 	 * subsystems which will access the unique ADC controller.
 	 */
 	struct hwspinlock *hwlock;
 	int channel_scale[SC27XX_ADC_CHANNEL_MAX];
 	u32 base;
 	int irq;
 };

 struct sc27xx_adc_linear_graph {
 	int volt0;
 	int adc0;
 	int volt1;
 	int adc1;
 };

 /*
  * According to the datasheet, we can convert one ADC value to one voltage value
  * through 2 points in the linear graph. If the voltage is less than 1.2v, we
  * should use the small-scale graph, and if more than 1.2v, we should use the
  * big-scale graph.
  */
 static struct sc27xx_adc_linear_graph big_scale_graph = {
 	4200, 3310,
 	3600, 2832,
 };

 static struct sc27xx_adc_linear_graph small_scale_graph = {
 	1000, 3413,
 	100, 341,
 };

 static const struct sc27xx_adc_linear_graph big_scale_graph_calib = {
 	4200, 856,
 	3600, 733,
 };

 static const struct sc27xx_adc_linear_graph small_scale_graph_calib = {
 	1000, 833,
 	100, 80,
 };

 static int sc27xx_adc_get_calib_data(u32 calib_data, int calib_adc)
 {
 	return ((calib_data & 0xff) + calib_adc - 128) * 4;
 }

 static int sc27xx_adc_scale_calibration(struct sc27xx_adc_data *data,
 					bool big_scale)
 {
 	const struct sc27xx_adc_linear_graph *calib_graph;
 	struct sc27xx_adc_linear_graph *graph;
 	struct nvmem_cell *cell;
 	const char *cell_name;
 	u32 calib_data = 0;
 	void *buf;
 	size_t len;

 	if (big_scale) {
 		calib_graph = &big_scale_graph_calib;
 		graph = &big_scale_graph;
 		cell_name = "big_scale_calib";
 	} else {
 		calib_graph = &small_scale_graph_calib;
 		graph = &small_scale_graph;
 		cell_name = "small_scale_calib";
 	}

 	cell = nvmem_cell_get(data->dev, cell_name);
 	if (IS_ERR(cell))
 		return PTR_ERR(cell);

 	buf = nvmem_cell_read(cell, &len);
 	nvmem_cell_put(cell);

 	if (IS_ERR(buf))
 		return PTR_ERR(buf);

 	memcpy(&calib_data, buf, min(len, sizeof(u32)));

 	/* Only need to calibrate the adc values in the linear graph. */
 	graph->adc0 = sc27xx_adc_get_calib_data(calib_data, calib_graph->adc0);
 	graph->adc1 = sc27xx_adc_get_calib_data(calib_data >> 8,
 						calib_graph->adc1);

 	kfree(buf);
 	return 0;
 }

 static int sc27xx_adc_get_ratio(int channel, int scale)
 {
 	switch (channel) {
 	case 1:
 	case 2:
 	case 3:
 	case 4:
 		return scale ? SC27XX_VOLT_RATIO(400, 1025) :
 			SC27XX_VOLT_RATIO(1, 1);
 	case 5:
 		return SC27XX_VOLT_RATIO(7, 29);
 	case 6:
 		return SC27XX_VOLT_RATIO(375, 9000);
 	case 7:
 	case 8:
 		return scale ? SC27XX_VOLT_RATIO(100, 125) :
 			SC27XX_VOLT_RATIO(1, 1);
 	case 19:
 		return SC27XX_VOLT_RATIO(1, 3);
 	default:
 		return SC27XX_VOLT_RATIO(1, 1);
 	}
 	return SC27XX_VOLT_RATIO(1, 1);
 }

 static int sc27xx_adc_read(struct sc27xx_adc_data *data, int channel,
 			   int scale, int *val)
 {
 	int ret;
 	u32 tmp, value, status;

 	ret = hwspin_lock_timeout_raw(data->hwlock, SC27XX_ADC_HWLOCK_TIMEOUT);
 	if (ret) {
 		dev_err(data->dev, "timeout to get the hwspinlock\n");
 		return ret;
 	}

 	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
 				 SC27XX_ADC_EN, SC27XX_ADC_EN);
 	if (ret)
 		goto unlock_adc;

 	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_INT_CLR,
 				 SC27XX_ADC_IRQ_CLR, SC27XX_ADC_IRQ_CLR);
 	if (ret)
 		goto disable_adc;

 	/* Configure the channel id and scale */
 	tmp = (scale << SC27XX_ADC_SCALE_SHIFT) & SC27XX_ADC_SCALE_MASK;
 	tmp |= channel & SC27XX_ADC_CHN_ID_MASK;
 	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CH_CFG,
 				 SC27XX_ADC_CHN_ID_MASK | SC27XX_ADC_SCALE_MASK,
 				 tmp);
 	if (ret)
 		goto disable_adc;

 	/* Select 12bit conversion mode, and only sample 1 time */
 	tmp = SC27XX_ADC_12BIT_MODE;
 	tmp |= (0 << SC27XX_ADC_RUN_NUM_SHIFT) & SC27XX_ADC_RUN_NUM_MASK;
 	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
 				 SC27XX_ADC_RUN_NUM_MASK | SC27XX_ADC_12BIT_MODE,
 				 tmp);
 	if (ret)
 		goto disable_adc;

 	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
 				 SC27XX_ADC_CHN_RUN, SC27XX_ADC_CHN_RUN);
 	if (ret)
 		goto disable_adc;

 	ret = regmap_read_poll_timeout(data->regmap,
 				       data->base + SC27XX_ADC_INT_RAW,
 				       status, (status & SC27XX_ADC_IRQ_RAW),
 				       SC27XX_ADC_POLL_RAW_STATUS,
 				       SC27XX_ADC_RDY_TIMEOUT);
 	if (ret) {
 		dev_err(data->dev, "read adc timeout, status = 0x%x\n", status);
 		goto disable_adc;
 	}

 	ret = regmap_read(data->regmap, data->base + SC27XX_ADC_DATA, &value);
 	if (ret)
 		goto disable_adc;

 	value &= SC27XX_ADC_DATA_MASK;

 disable_adc:
 	regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
 			   SC27XX_ADC_EN, 0);
 unlock_adc:
 	hwspin_unlock_raw(data->hwlock);

 	if (!ret)
 		*val = value;

 	return ret;
 }

 static void sc27xx_adc_volt_ratio(struct sc27xx_adc_data *data,
 				  int channel, int scale,
 				  u32 *div_numerator, u32 *div_denominator)
 {
 	u32 ratio = sc27xx_adc_get_ratio(channel, scale);

 	*div_numerator = ratio >> SC27XX_RATIO_NUMERATOR_OFFSET;
 	*div_denominator = ratio & SC27XX_RATIO_DENOMINATOR_MASK;
 }

 static int sc27xx_adc_to_volt(struct sc27xx_adc_linear_graph *graph,
 			      int raw_adc)
 {
 	int tmp;

 	tmp = (graph->volt0 - graph->volt1) * (raw_adc - graph->adc1);
 	tmp /= (graph->adc0 - graph->adc1);
 	tmp += graph->volt1;

 	return tmp < 0 ? 0 : tmp;
 }

 static int sc27xx_adc_convert_volt(struct sc27xx_adc_data *data, int channel,
 				   int scale, int raw_adc)
 {
 	u32 numerator, denominator;
 	u32 volt;

 	/*
 	 * Convert ADC values to voltage values according to the linear graph,
 	 * and channel 5 and channel 1 has been calibrated, so we can just
 	 * return the voltage values calculated by the linear graph. But other
 	 * channels need be calculated to the real voltage values with the
 	 * voltage ratio.
 	 */
 	switch (channel) {
 	case 5:
 		return sc27xx_adc_to_volt(&big_scale_graph, raw_adc);

 	case 1:
 		return sc27xx_adc_to_volt(&small_scale_graph, raw_adc);

 	default:
 		volt = sc27xx_adc_to_volt(&small_scale_graph, raw_adc);
 		break;
 	}

 	sc27xx_adc_volt_ratio(data, channel, scale, &numerator, &denominator);

 	return (volt * denominator + numerator / 2) / numerator;
 }

 static int sc27xx_adc_read_processed(struct sc27xx_adc_data *data,
 				     int channel, int scale, int *val)
 {
 	int ret, raw_adc;

 	ret = sc27xx_adc_read(data, channel, scale, &raw_adc);
 	if (ret)
 		return ret;

 	*val = sc27xx_adc_convert_volt(data, channel, scale, raw_adc);
 	return 0;
 }

 static int sc27xx_adc_read_raw(struct iio_dev *indio_dev,
 			       struct iio_chan_spec const *chan,
 			       int *val, int *val2, long mask)
 {
 	struct sc27xx_adc_data *data = iio_priv(indio_dev);
 	int scale = data->channel_scale[chan->channel];
 	int ret, tmp;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&indio_dev->mlock);
 		ret = sc27xx_adc_read(data, chan->channel, scale, &tmp);
 		mutex_unlock(&indio_dev->mlock);

 		if (ret)
 			return ret;

 		*val = tmp;
 		return IIO_VAL_INT;

 	case IIO_CHAN_INFO_PROCESSED:
 		mutex_lock(&indio_dev->mlock);
 		ret = sc27xx_adc_read_processed(data, chan->channel, scale,
 						&tmp);
 		mutex_unlock(&indio_dev->mlock);

 		if (ret)
 			return ret;

 		*val = tmp;
 		return IIO_VAL_INT;

 	case IIO_CHAN_INFO_SCALE:
 		*val = scale;
 		return IIO_VAL_INT;

 	default:
 		return -EINVAL;
 	}
 }

 static int sc27xx_adc_write_raw(struct iio_dev *indio_dev,
 				struct iio_chan_spec const *chan,
 				int val, int val2, long mask)
 {
 	struct sc27xx_adc_data *data = iio_priv(indio_dev);

 	switch (mask) {
 	case IIO_CHAN_INFO_SCALE:
 		data->channel_scale[chan->channel] = val;
 		return IIO_VAL_INT;

 	default:
 		return -EINVAL;
 	}
 }

 static const struct iio_info sc27xx_info = {
 	.read_raw = &sc27xx_adc_read_raw,
 	.write_raw = &sc27xx_adc_write_raw,
 };

 #define SC27XX_ADC_CHANNEL(index, mask) {			\
 	.type = IIO_VOLTAGE,					\
 	.channel = index,					\
 	.info_mask_separate = mask | BIT(IIO_CHAN_INFO_SCALE),	\
 	.datasheet_name = "CH##index",				\
 	.indexed = 1,						\
 }

 static const struct iio_chan_spec sc27xx_channels[] = {
 	SC27XX_ADC_CHANNEL(0, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(1, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(2, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(3, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(4, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(5, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(6, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(7, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(8, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(9, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(10, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(11, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(12, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(13, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(14, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(15, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(16, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(17, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(18, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(19, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(20, BIT(IIO_CHAN_INFO_RAW)),
 	SC27XX_ADC_CHANNEL(21, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(22, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(23, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(24, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(25, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(26, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(27, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(28, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(29, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(30, BIT(IIO_CHAN_INFO_PROCESSED)),
 	SC27XX_ADC_CHANNEL(31, BIT(IIO_CHAN_INFO_PROCESSED)),
 };

 static int sc27xx_adc_enable(struct sc27xx_adc_data *data)
 {
 	int ret;

 	ret = regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
 				 SC27XX_MODULE_ADC_EN, SC27XX_MODULE_ADC_EN);
 	if (ret)
 		return ret;

 	/* Enable ADC work clock and controller clock */
 	ret = regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
 				 SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN,
 				 SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN);
 	if (ret)
 		goto disable_adc;

 	/* ADC channel scales' calibration from nvmem device */
 	ret = sc27xx_adc_scale_calibration(data, true);
 	if (ret)
 		goto disable_clk;

 	ret = sc27xx_adc_scale_calibration(data, false);
 	if (ret)
 		goto disable_clk;

 	return 0;

 disable_clk:
 	regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
 			   SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN, 0);
 disable_adc:
 	regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
 			   SC27XX_MODULE_ADC_EN, 0);

 	return ret;
 }

 static void sc27xx_adc_disable(void *_data)
 {
 	struct sc27xx_adc_data *data = _data;

 	/* Disable ADC work clock and controller clock */
 	regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
 			   SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN, 0);

 	regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
 			   SC27XX_MODULE_ADC_EN, 0);
 }

 static int sc27xx_adc_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
 	struct sc27xx_adc_data *sc27xx_data;
 	struct iio_dev *indio_dev;
 	int ret;

 	indio_dev = devm_iio_device_alloc(dev, sizeof(*sc27xx_data));
 	if (!indio_dev)
 		return -ENOMEM;

 	sc27xx_data = iio_priv(indio_dev);

 	sc27xx_data->regmap = dev_get_regmap(dev->parent, NULL);
 	if (!sc27xx_data->regmap) {
 		dev_err(dev, "failed to get ADC regmap\n");
 		return -ENODEV;
 	}

 	ret = of_property_read_u32(np, "reg", &sc27xx_data->base);
 	if (ret) {
 		dev_err(dev, "failed to get ADC base address\n");
 		return ret;
 	}

 	sc27xx_data->irq = platform_get_irq(pdev, 0);
 	if (sc27xx_data->irq < 0)
 		return sc27xx_data->irq;

 	ret = of_hwspin_lock_get_id(np, 0);
 	if (ret < 0) {
 		dev_err(dev, "failed to get hwspinlock id\n");
 		return ret;
 	}

 	sc27xx_data->hwlock = devm_hwspin_lock_request_specific(dev, ret);
 	if (!sc27xx_data->hwlock) {
 		dev_err(dev, "failed to request hwspinlock\n");
 		return -ENXIO;
 	}

 	sc27xx_data->dev = dev;

 	ret = sc27xx_adc_enable(sc27xx_data);
 	if (ret) {
 		dev_err(dev, "failed to enable ADC module\n");
 		return ret;
 	}

 	ret = devm_add_action_or_reset(dev, sc27xx_adc_disable, sc27xx_data);
 	if (ret) {
 		dev_err(dev, "failed to add ADC disable action\n");
 		return ret;
 	}

 	indio_dev->dev.parent = dev;
 	indio_dev->name = dev_name(dev);
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &sc27xx_info;
 	indio_dev->channels = sc27xx_channels;
 	indio_dev->num_channels = ARRAY_SIZE(sc27xx_channels);
 	ret = devm_iio_device_register(dev, indio_dev);
 	if (ret)
 		dev_err(dev, "could not register iio (ADC)");

 	return ret;
 }

 static const struct of_device_id sc27xx_adc_of_match[] = {
 	{ .compatible = "sprd,sc2731-adc", },
 	{ }
 };

 static struct platform_driver sc27xx_adc_driver = {
 	.probe = sc27xx_adc_probe,
 	.driver = {
 		.name = "sc27xx-adc",
 		.of_match_table = sc27xx_adc_of_match,
 	},
 };

 module_platform_driver(sc27xx_adc_driver);

 MODULE_AUTHOR("Freeman Liu <freeman.liu@spreadtrum.com>");
 MODULE_DESCRIPTION("Spreadtrum SC27XX ADC Driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	// Copyright (C) 2018 Spreadtrum Communications Inc.

	#include <linux/hwspinlock.h>
	#include <linux/iio/iio.h>
	#include <linux/module.h>
	#include <linux/nvmem-consumer.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>
	#include <linux/slab.h>

	/* PMIC global registers definition */
	#define SC27XX_MODULE_EN 0xc08
	#define SC27XX_MODULE_ADC_EN BIT(5)
	#define SC27XX_ARM_CLK_EN 0xc10
	#define SC27XX_CLK_ADC_EN BIT(5)
	#define SC27XX_CLK_ADC_CLK_EN BIT(6)

	/* ADC controller registers definition */
	#define SC27XX_ADC_CTL 0x0
	#define SC27XX_ADC_CH_CFG 0x4
	#define SC27XX_ADC_DATA 0x4c
	#define SC27XX_ADC_INT_EN 0x50
	#define SC27XX_ADC_INT_CLR 0x54
	#define SC27XX_ADC_INT_STS 0x58
	#define SC27XX_ADC_INT_RAW 0x5c

	/* Bits and mask definition for SC27XX_ADC_CTL register */
	#define SC27XX_ADC_EN BIT(0)
	#define SC27XX_ADC_CHN_RUN BIT(1)
	#define SC27XX_ADC_12BIT_MODE BIT(2)
	#define SC27XX_ADC_RUN_NUM_MASK GENMASK(7, 4)
	#define SC27XX_ADC_RUN_NUM_SHIFT 4

	/* Bits and mask definition for SC27XX_ADC_CH_CFG register */
	#define SC27XX_ADC_CHN_ID_MASK GENMASK(4, 0)
	#define SC27XX_ADC_SCALE_MASK GENMASK(10, 8)
	#define SC27XX_ADC_SCALE_SHIFT 8

	/* Bits definitions for SC27XX_ADC_INT_EN registers */
	#define SC27XX_ADC_IRQ_EN BIT(0)

	/* Bits definitions for SC27XX_ADC_INT_CLR registers */
	#define SC27XX_ADC_IRQ_CLR BIT(0)

	/* Bits definitions for SC27XX_ADC_INT_RAW registers */
	#define SC27XX_ADC_IRQ_RAW BIT(0)

	/* Mask definition for SC27XX_ADC_DATA register */
	#define SC27XX_ADC_DATA_MASK GENMASK(11, 0)

	/* Timeout (ms) for the trylock of hardware spinlocks */
	#define SC27XX_ADC_HWLOCK_TIMEOUT 5000

	/* Timeout (us) for ADC data conversion according to ADC datasheet */
	#define SC27XX_ADC_RDY_TIMEOUT 1000000
	#define SC27XX_ADC_POLL_RAW_STATUS 500

	/* Maximum ADC channel number */
	#define SC27XX_ADC_CHANNEL_MAX 32

	/* ADC voltage ratio definition */
	#define SC27XX_VOLT_RATIO(n, d) \
	(((n) << SC27XX_RATIO_NUMERATOR_OFFSET) \| (d))
	#define SC27XX_RATIO_NUMERATOR_OFFSET 16
	#define SC27XX_RATIO_DENOMINATOR_MASK GENMASK(15, 0)

	struct sc27xx_adc_data {
	struct device *dev;
	struct regmap *regmap;
	/*
	* One hardware spinlock to synchronize between the multiple
	* subsystems which will access the unique ADC controller.
	*/
	struct hwspinlock *hwlock;
	int channel_scale[SC27XX_ADC_CHANNEL_MAX];
	u32 base;
	int irq;
	};

	struct sc27xx_adc_linear_graph {
	int volt0;
	int adc0;
	int volt1;
	int adc1;
	};

	/*
	* According to the datasheet, we can convert one ADC value to one voltage value
	* through 2 points in the linear graph. If the voltage is less than 1.2v, we
	* should use the small-scale graph, and if more than 1.2v, we should use the
	* big-scale graph.
	*/
	static struct sc27xx_adc_linear_graph big_scale_graph = {
	4200, 3310,
	3600, 2832,
	};

	static struct sc27xx_adc_linear_graph small_scale_graph = {
	1000, 3413,
	100, 341,
	};

	static const struct sc27xx_adc_linear_graph big_scale_graph_calib = {
	4200, 856,
	3600, 733,
	};

	static const struct sc27xx_adc_linear_graph small_scale_graph_calib = {
	1000, 833,
	100, 80,
	};

	static int sc27xx_adc_get_calib_data(u32 calib_data, int calib_adc)
	{
	return ((calib_data & 0xff) + calib_adc - 128) * 4;
	}

	static int sc27xx_adc_scale_calibration(struct sc27xx_adc_data *data,
	bool big_scale)
	{
	const struct sc27xx_adc_linear_graph *calib_graph;
	struct sc27xx_adc_linear_graph *graph;
	struct nvmem_cell *cell;
	const char *cell_name;
	u32 calib_data = 0;
	void *buf;
	size_t len;

	if (big_scale) {
	calib_graph = &big_scale_graph_calib;
	graph = &big_scale_graph;
	cell_name = "big_scale_calib";
	} else {
	calib_graph = &small_scale_graph_calib;
	graph = &small_scale_graph;
	cell_name = "small_scale_calib";
	}

	cell = nvmem_cell_get(data->dev, cell_name);
	if (IS_ERR(cell))
	return PTR_ERR(cell);

	buf = nvmem_cell_read(cell, &len);
	nvmem_cell_put(cell);

	if (IS_ERR(buf))
	return PTR_ERR(buf);

	memcpy(&calib_data, buf, min(len, sizeof(u32)));

	/* Only need to calibrate the adc values in the linear graph. */
	graph->adc0 = sc27xx_adc_get_calib_data(calib_data, calib_graph->adc0);
	graph->adc1 = sc27xx_adc_get_calib_data(calib_data >> 8,
	calib_graph->adc1);

	kfree(buf);
	return 0;
	}

	static int sc27xx_adc_get_ratio(int channel, int scale)
	{
	switch (channel) {
	case 1:
	case 2:
	case 3:
	case 4:
	return scale ? SC27XX_VOLT_RATIO(400, 1025) :
	SC27XX_VOLT_RATIO(1, 1);
	case 5:
	return SC27XX_VOLT_RATIO(7, 29);
	case 6:
	return SC27XX_VOLT_RATIO(375, 9000);
	case 7:
	case 8:
	return scale ? SC27XX_VOLT_RATIO(100, 125) :
	SC27XX_VOLT_RATIO(1, 1);
	case 19:
	return SC27XX_VOLT_RATIO(1, 3);
	default:
	return SC27XX_VOLT_RATIO(1, 1);
	}
	return SC27XX_VOLT_RATIO(1, 1);
	}

	static int sc27xx_adc_read(struct sc27xx_adc_data *data, int channel,
	int scale, int *val)
	{
	int ret;
	u32 tmp, value, status;

	ret = hwspin_lock_timeout_raw(data->hwlock, SC27XX_ADC_HWLOCK_TIMEOUT);
	if (ret) {
	dev_err(data->dev, "timeout to get the hwspinlock\n");
	return ret;
	}

	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
	SC27XX_ADC_EN, SC27XX_ADC_EN);
	if (ret)
	goto unlock_adc;

	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_INT_CLR,
	SC27XX_ADC_IRQ_CLR, SC27XX_ADC_IRQ_CLR);
	if (ret)
	goto disable_adc;

	/* Configure the channel id and scale */
	tmp = (scale << SC27XX_ADC_SCALE_SHIFT) & SC27XX_ADC_SCALE_MASK;
	tmp \|= channel & SC27XX_ADC_CHN_ID_MASK;
	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CH_CFG,
	SC27XX_ADC_CHN_ID_MASK \| SC27XX_ADC_SCALE_MASK,
	tmp);
	if (ret)
	goto disable_adc;

	/* Select 12bit conversion mode, and only sample 1 time */
	tmp = SC27XX_ADC_12BIT_MODE;
	tmp \|= (0 << SC27XX_ADC_RUN_NUM_SHIFT) & SC27XX_ADC_RUN_NUM_MASK;
	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
	SC27XX_ADC_RUN_NUM_MASK \| SC27XX_ADC_12BIT_MODE,
	tmp);
	if (ret)
	goto disable_adc;

	ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
	SC27XX_ADC_CHN_RUN, SC27XX_ADC_CHN_RUN);
	if (ret)
	goto disable_adc;

	ret = regmap_read_poll_timeout(data->regmap,
	data->base + SC27XX_ADC_INT_RAW,
	status, (status & SC27XX_ADC_IRQ_RAW),
	SC27XX_ADC_POLL_RAW_STATUS,
	SC27XX_ADC_RDY_TIMEOUT);
	if (ret) {
	dev_err(data->dev, "read adc timeout, status = 0x%x\n", status);
	goto disable_adc;
	}

	ret = regmap_read(data->regmap, data->base + SC27XX_ADC_DATA, &value);
	if (ret)
	goto disable_adc;

	value &= SC27XX_ADC_DATA_MASK;

	disable_adc:
	regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
	SC27XX_ADC_EN, 0);
	unlock_adc:
	hwspin_unlock_raw(data->hwlock);

	if (!ret)
	*val = value;

	return ret;
	}

	static void sc27xx_adc_volt_ratio(struct sc27xx_adc_data *data,
	int channel, int scale,
	u32 div_numerator, u32 div_denominator)
	{
	u32 ratio = sc27xx_adc_get_ratio(channel, scale);

	*div_numerator = ratio >> SC27XX_RATIO_NUMERATOR_OFFSET;
	*div_denominator = ratio & SC27XX_RATIO_DENOMINATOR_MASK;
	}

	static int sc27xx_adc_to_volt(struct sc27xx_adc_linear_graph *graph,
	int raw_adc)
	{
	int tmp;

	tmp = (graph->volt0 - graph->volt1) * (raw_adc - graph->adc1);
	tmp /= (graph->adc0 - graph->adc1);
	tmp += graph->volt1;

	return tmp < 0 ? 0 : tmp;
	}

	static int sc27xx_adc_convert_volt(struct sc27xx_adc_data *data, int channel,
	int scale, int raw_adc)
	{
	u32 numerator, denominator;
	u32 volt;

	/*
	* Convert ADC values to voltage values according to the linear graph,
	* and channel 5 and channel 1 has been calibrated, so we can just
	* return the voltage values calculated by the linear graph. But other
	* channels need be calculated to the real voltage values with the
	* voltage ratio.
	*/
	switch (channel) {
	case 5:
	return sc27xx_adc_to_volt(&big_scale_graph, raw_adc);

	case 1:
	return sc27xx_adc_to_volt(&small_scale_graph, raw_adc);

	default:
	volt = sc27xx_adc_to_volt(&small_scale_graph, raw_adc);
	break;
	}

	sc27xx_adc_volt_ratio(data, channel, scale, &numerator, &denominator);

	return (volt * denominator + numerator / 2) / numerator;
	}

	static int sc27xx_adc_read_processed(struct sc27xx_adc_data *data,
	int channel, int scale, int *val)
	{
	int ret, raw_adc;

	ret = sc27xx_adc_read(data, channel, scale, &raw_adc);
	if (ret)
	return ret;

	*val = sc27xx_adc_convert_volt(data, channel, scale, raw_adc);
	return 0;
	}

	static int sc27xx_adc_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct sc27xx_adc_data *data = iio_priv(indio_dev);
	int scale = data->channel_scale[chan->channel];
	int ret, tmp;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	mutex_lock(&indio_dev->mlock);
	ret = sc27xx_adc_read(data, chan->channel, scale, &tmp);
	mutex_unlock(&indio_dev->mlock);

	if (ret)
	return ret;

	*val = tmp;
	return IIO_VAL_INT;

	case IIO_CHAN_INFO_PROCESSED:
	mutex_lock(&indio_dev->mlock);
	ret = sc27xx_adc_read_processed(data, chan->channel, scale,
	&tmp);
	mutex_unlock(&indio_dev->mlock);

	if (ret)
	return ret;

	*val = tmp;
	return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:
	*val = scale;
	return IIO_VAL_INT;

	default:
	return -EINVAL;
	}
	}

	static int sc27xx_adc_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct sc27xx_adc_data *data = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_SCALE:
	data->channel_scale[chan->channel] = val;
	return IIO_VAL_INT;

	default:
	return -EINVAL;
	}
	}

	static const struct iio_info sc27xx_info = {
	.read_raw = &sc27xx_adc_read_raw,
	.write_raw = &sc27xx_adc_write_raw,
	};

	#define SC27XX_ADC_CHANNEL(index, mask) { \
	.type = IIO_VOLTAGE, \
	.channel = index, \
	.info_mask_separate = mask \| BIT(IIO_CHAN_INFO_SCALE), \
	.datasheet_name = "CH##index", \
	.indexed = 1, \
	}

	static const struct iio_chan_spec sc27xx_channels[] = {
	SC27XX_ADC_CHANNEL(0, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(1, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(2, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(3, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(4, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(5, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(6, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(7, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(8, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(9, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(10, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(11, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(12, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(13, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(14, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(15, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(16, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(17, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(18, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(19, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(20, BIT(IIO_CHAN_INFO_RAW)),
	SC27XX_ADC_CHANNEL(21, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(22, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(23, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(24, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(25, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(26, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(27, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(28, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(29, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(30, BIT(IIO_CHAN_INFO_PROCESSED)),
	SC27XX_ADC_CHANNEL(31, BIT(IIO_CHAN_INFO_PROCESSED)),
	};

	static int sc27xx_adc_enable(struct sc27xx_adc_data *data)
	{
	int ret;

	ret = regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
	SC27XX_MODULE_ADC_EN, SC27XX_MODULE_ADC_EN);
	if (ret)
	return ret;

	/* Enable ADC work clock and controller clock */
	ret = regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
	SC27XX_CLK_ADC_EN \| SC27XX_CLK_ADC_CLK_EN,
	SC27XX_CLK_ADC_EN \| SC27XX_CLK_ADC_CLK_EN);
	if (ret)
	goto disable_adc;

	/* ADC channel scales' calibration from nvmem device */
	ret = sc27xx_adc_scale_calibration(data, true);
	if (ret)
	goto disable_clk;

	ret = sc27xx_adc_scale_calibration(data, false);
	if (ret)
	goto disable_clk;

	return 0;

	disable_clk:
	regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
	SC27XX_CLK_ADC_EN \| SC27XX_CLK_ADC_CLK_EN, 0);
	disable_adc:
	regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
	SC27XX_MODULE_ADC_EN, 0);

	return ret;
	}

	static void sc27xx_adc_disable(void *_data)
	{
	struct sc27xx_adc_data *data = _data;

	/* Disable ADC work clock and controller clock */
	regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
	SC27XX_CLK_ADC_EN \| SC27XX_CLK_ADC_CLK_EN, 0);

	regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
	SC27XX_MODULE_ADC_EN, 0);
	}

	static int sc27xx_adc_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct sc27xx_adc_data *sc27xx_data;
	struct iio_dev *indio_dev;
	int ret;

	indio_dev = devm_iio_device_alloc(dev, sizeof(*sc27xx_data));
	if (!indio_dev)
	return -ENOMEM;

	sc27xx_data = iio_priv(indio_dev);

	sc27xx_data->regmap = dev_get_regmap(dev->parent, NULL);
	if (!sc27xx_data->regmap) {
	dev_err(dev, "failed to get ADC regmap\n");
	return -ENODEV;
	}

	ret = of_property_read_u32(np, "reg", &sc27xx_data->base);
	if (ret) {
	dev_err(dev, "failed to get ADC base address\n");
	return ret;
	}

	sc27xx_data->irq = platform_get_irq(pdev, 0);
	if (sc27xx_data->irq < 0)
	return sc27xx_data->irq;

	ret = of_hwspin_lock_get_id(np, 0);
	if (ret < 0) {
	dev_err(dev, "failed to get hwspinlock id\n");
	return ret;
	}

	sc27xx_data->hwlock = devm_hwspin_lock_request_specific(dev, ret);
	if (!sc27xx_data->hwlock) {
	dev_err(dev, "failed to request hwspinlock\n");
	return -ENXIO;
	}

	sc27xx_data->dev = dev;

	ret = sc27xx_adc_enable(sc27xx_data);
	if (ret) {
	dev_err(dev, "failed to enable ADC module\n");
	return ret;
	}

	ret = devm_add_action_or_reset(dev, sc27xx_adc_disable, sc27xx_data);
	if (ret) {
	dev_err(dev, "failed to add ADC disable action\n");
	return ret;
	}

	indio_dev->dev.parent = dev;
	indio_dev->name = dev_name(dev);
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &sc27xx_info;
	indio_dev->channels = sc27xx_channels;
	indio_dev->num_channels = ARRAY_SIZE(sc27xx_channels);
	ret = devm_iio_device_register(dev, indio_dev);
	if (ret)
	dev_err(dev, "could not register iio (ADC)");

	return ret;
	}

	static const struct of_device_id sc27xx_adc_of_match[] = {
	{ .compatible = "sprd,sc2731-adc", },
	{ }
	};

	static struct platform_driver sc27xx_adc_driver = {
	.probe = sc27xx_adc_probe,
	.driver = {
	.name = "sc27xx-adc",
	.of_match_table = sc27xx_adc_of_match,
	},
	};

	module_platform_driver(sc27xx_adc_driver);

	MODULE_AUTHOR("Freeman Liu <freeman.liu@spreadtrum.com>");
	MODULE_DESCRIPTION("Spreadtrum SC27XX ADC Driver");
	MODULE_LICENSE("GPL v2");