drivers/iio/adc/rcar-gyroadc.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Renesas R-Car GyroADC driver
  *
  * Copyright 2016 Marek Vasut <marek.vasut@gmail.com>
  */

 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/delay.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/io.h>
 #include <linux/clk.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/pm_runtime.h>

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

 #define DRIVER_NAME				"rcar-gyroadc"

 /* GyroADC registers. */
 #define RCAR_GYROADC_MODE_SELECT		0x00
 #define RCAR_GYROADC_MODE_SELECT_1_MB88101A	0x0
 #define RCAR_GYROADC_MODE_SELECT_2_ADCS7476	0x1
 #define RCAR_GYROADC_MODE_SELECT_3_MAX1162	0x3

 #define RCAR_GYROADC_START_STOP			0x04
 #define RCAR_GYROADC_START_STOP_START		BIT(0)

 #define RCAR_GYROADC_CLOCK_LENGTH		0x08
 #define RCAR_GYROADC_1_25MS_LENGTH		0x0c

 #define RCAR_GYROADC_REALTIME_DATA(ch)		(0x10 + ((ch) * 4))
 #define RCAR_GYROADC_100MS_ADDED_DATA(ch)	(0x30 + ((ch) * 4))
 #define RCAR_GYROADC_10MS_AVG_DATA(ch)		(0x50 + ((ch) * 4))

 #define RCAR_GYROADC_FIFO_STATUS		0x70
 #define RCAR_GYROADC_FIFO_STATUS_EMPTY(ch)	BIT(0 + (4 * (ch)))
 #define RCAR_GYROADC_FIFO_STATUS_FULL(ch)	BIT(1 + (4 * (ch)))
 #define RCAR_GYROADC_FIFO_STATUS_ERROR(ch)	BIT(2 + (4 * (ch)))

 #define RCAR_GYROADC_INTR			0x74
 #define RCAR_GYROADC_INTR_INT			BIT(0)

 #define RCAR_GYROADC_INTENR			0x78
 #define RCAR_GYROADC_INTENR_INTEN		BIT(0)

 #define RCAR_GYROADC_SAMPLE_RATE		800	/* Hz */

 #define RCAR_GYROADC_RUNTIME_PM_DELAY_MS	2000

 enum rcar_gyroadc_model {
 	RCAR_GYROADC_MODEL_DEFAULT,
 	RCAR_GYROADC_MODEL_R8A7792,
 };

 struct rcar_gyroadc {
 	struct device			*dev;
 	void __iomem			*regs;
 	struct clk			*clk;
 	struct regulator		*vref[8];
 	unsigned int			num_channels;
 	enum rcar_gyroadc_model		model;
 	unsigned int			mode;
 	unsigned int			sample_width;
 };

 static void rcar_gyroadc_hw_init(struct rcar_gyroadc *priv)
 {
 	const unsigned long clk_mhz = clk_get_rate(priv->clk) / 1000000;
 	const unsigned long clk_mul =
 		(priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) ? 10 : 5;
 	unsigned long clk_len = clk_mhz * clk_mul;

 	/*
 	 * According to the R-Car Gen2 datasheet Rev. 1.01, Sept 08 2014,
 	 * page 77-7, clock length must be even number. If it's odd number,
 	 * add one.
 	 */
 	if (clk_len & 1)
 		clk_len++;

 	/* Stop the GyroADC. */
 	writel(0, priv->regs + RCAR_GYROADC_START_STOP);

 	/* Disable IRQ on V2H. */
 	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
 		writel(0, priv->regs + RCAR_GYROADC_INTENR);

 	/* Set mode and timing. */
 	writel(priv->mode, priv->regs + RCAR_GYROADC_MODE_SELECT);
 	writel(clk_len, priv->regs + RCAR_GYROADC_CLOCK_LENGTH);
 	writel(clk_mhz * 1250, priv->regs + RCAR_GYROADC_1_25MS_LENGTH);
 }

 static void rcar_gyroadc_hw_start(struct rcar_gyroadc *priv)
 {
 	/* Start sampling. */
 	writel(RCAR_GYROADC_START_STOP_START,
 	       priv->regs + RCAR_GYROADC_START_STOP);

 	/*
 	 * Wait for the first conversion to complete. This is longer than
 	 * the 1.25 mS in the datasheet because 1.25 mS is not enough for
 	 * the hardware to deliver the first sample and the hardware does
 	 * then return zeroes instead of valid data.
 	 */
 	mdelay(3);
 }

 static void rcar_gyroadc_hw_stop(struct rcar_gyroadc *priv)
 {
 	/* Stop the GyroADC. */
 	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
 }

 #define RCAR_GYROADC_CHAN(_idx) {				\
 	.type			= IIO_VOLTAGE,			\
 	.indexed		= 1,				\
 	.channel		= (_idx),			\
 	.info_mask_separate	= BIT(IIO_CHAN_INFO_RAW) |	\
 				  BIT(IIO_CHAN_INFO_SCALE),	\
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
 }

 static const struct iio_chan_spec rcar_gyroadc_iio_channels_1[] = {
 	RCAR_GYROADC_CHAN(0),
 	RCAR_GYROADC_CHAN(1),
 	RCAR_GYROADC_CHAN(2),
 	RCAR_GYROADC_CHAN(3),
 };

 static const struct iio_chan_spec rcar_gyroadc_iio_channels_2[] = {
 	RCAR_GYROADC_CHAN(0),
 	RCAR_GYROADC_CHAN(1),
 	RCAR_GYROADC_CHAN(2),
 	RCAR_GYROADC_CHAN(3),
 	RCAR_GYROADC_CHAN(4),
 	RCAR_GYROADC_CHAN(5),
 	RCAR_GYROADC_CHAN(6),
 	RCAR_GYROADC_CHAN(7),
 };

 static const struct iio_chan_spec rcar_gyroadc_iio_channels_3[] = {
 	RCAR_GYROADC_CHAN(0),
 	RCAR_GYROADC_CHAN(1),
 	RCAR_GYROADC_CHAN(2),
 	RCAR_GYROADC_CHAN(3),
 	RCAR_GYROADC_CHAN(4),
 	RCAR_GYROADC_CHAN(5),
 	RCAR_GYROADC_CHAN(6),
 	RCAR_GYROADC_CHAN(7),
 };

 static int rcar_gyroadc_set_power(struct rcar_gyroadc *priv, bool on)
 {
 	struct device *dev = priv->dev;

 	if (on) {
 		return pm_runtime_resume_and_get(dev);
 	} else {
 		pm_runtime_mark_last_busy(dev);
 		return pm_runtime_put_autosuspend(dev);
 	}
 }

 static int rcar_gyroadc_read_raw(struct iio_dev *indio_dev,
 				 struct iio_chan_spec const *chan,
 				 int *val, int *val2, long mask)
 {
 	struct rcar_gyroadc *priv = iio_priv(indio_dev);
 	struct regulator *consumer;
 	unsigned int datareg = RCAR_GYROADC_REALTIME_DATA(chan->channel);
 	unsigned int vref;
 	int ret;

 	/*
 	 * MB88101 is special in that it has only single regulator for
 	 * all four channels.
 	 */
 	if (priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A)
 		consumer = priv->vref[0];
 	else
 		consumer = priv->vref[chan->channel];

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		if (chan->type != IIO_VOLTAGE)
 			return -EINVAL;

 		/* Channel not connected. */
 		if (!consumer)
 			return -EINVAL;

 		ret = iio_device_claim_direct_mode(indio_dev);
 		if (ret)
 			return ret;

 		ret = rcar_gyroadc_set_power(priv, true);
 		if (ret < 0) {
 			iio_device_release_direct_mode(indio_dev);
 			return ret;
 		}

 		*val = readl(priv->regs + datareg);
 		*val &= BIT(priv->sample_width) - 1;

 		ret = rcar_gyroadc_set_power(priv, false);
 		iio_device_release_direct_mode(indio_dev);
 		if (ret < 0)
 			return ret;

 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		/* Channel not connected. */
 		if (!consumer)
 			return -EINVAL;

 		vref = regulator_get_voltage(consumer);
 		*val = vref / 1000;
 		*val2 = 1 << priv->sample_width;

 		return IIO_VAL_FRACTIONAL;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*val = RCAR_GYROADC_SAMPLE_RATE;

 		return IIO_VAL_INT;
 	default:
 		return -EINVAL;
 	}
 }

 static int rcar_gyroadc_reg_access(struct iio_dev *indio_dev,
 				   unsigned int reg, unsigned int writeval,
 				   unsigned int *readval)
 {
 	struct rcar_gyroadc *priv = iio_priv(indio_dev);
 	unsigned int maxreg = RCAR_GYROADC_FIFO_STATUS;

 	if (readval == NULL)
 		return -EINVAL;

 	if (reg % 4)
 		return -EINVAL;

 	/* Handle the V2H case with extra interrupt block. */
 	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
 		maxreg = RCAR_GYROADC_INTENR;

 	if (reg > maxreg)
 		return -EINVAL;

 	*readval = readl(priv->regs + reg);

 	return 0;
 }

 static const struct iio_info rcar_gyroadc_iio_info = {
 	.read_raw		= rcar_gyroadc_read_raw,
 	.debugfs_reg_access	= rcar_gyroadc_reg_access,
 };

 static const struct of_device_id rcar_gyroadc_match[] = {
 	{
 		/* R-Car compatible GyroADC */
 		.compatible	= "renesas,rcar-gyroadc",
 		.data		= (void *)RCAR_GYROADC_MODEL_DEFAULT,
 	}, {
 		/* R-Car V2H specialty with interrupt registers. */
 		.compatible	= "renesas,r8a7792-gyroadc",
 		.data		= (void *)RCAR_GYROADC_MODEL_R8A7792,
 	}, {
 		/* sentinel */
 	}
 };

 MODULE_DEVICE_TABLE(of, rcar_gyroadc_match);

 static const struct of_device_id rcar_gyroadc_child_match[] = {
 	/* Mode 1 ADCs */
 	{
 		.compatible	= "fujitsu,mb88101a",
 		.data		= (void *)RCAR_GYROADC_MODE_SELECT_1_MB88101A,
 	},
 	/* Mode 2 ADCs */
 	{
 		.compatible	= "ti,adcs7476",
 		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
 	}, {
 		.compatible	= "ti,adc121",
 		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
 	}, {
 		.compatible	= "adi,ad7476",
 		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
 	},
 	/* Mode 3 ADCs */
 	{
 		.compatible	= "maxim,max1162",
 		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
 	}, {
 		.compatible	= "maxim,max11100",
 		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
 	},
 	{ /* sentinel */ }
 };

 static int rcar_gyroadc_parse_subdevs(struct iio_dev *indio_dev)
 {
 	const struct of_device_id *of_id;
 	const struct iio_chan_spec *channels;
 	struct rcar_gyroadc *priv = iio_priv(indio_dev);
 	struct device *dev = priv->dev;
 	struct device_node *np = dev->of_node;
 	struct device_node *child;
 	struct regulator *vref;
 	unsigned int reg;
 	unsigned int adcmode = -1, childmode;
 	unsigned int sample_width;
 	unsigned int num_channels;
 	int ret, first = 1;

 	for_each_child_of_node(np, child) {
 		of_id = of_match_node(rcar_gyroadc_child_match, child);
 		if (!of_id) {
 			dev_err(dev, "Ignoring unsupported ADC \"%pOFn\".",
 				child);
 			continue;
 		}

 		childmode = (uintptr_t)of_id->data;
 		switch (childmode) {
 		case RCAR_GYROADC_MODE_SELECT_1_MB88101A:
 			sample_width = 12;
 			channels = rcar_gyroadc_iio_channels_1;
 			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_1);
 			break;
 		case RCAR_GYROADC_MODE_SELECT_2_ADCS7476:
 			sample_width = 15;
 			channels = rcar_gyroadc_iio_channels_2;
 			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_2);
 			break;
 		case RCAR_GYROADC_MODE_SELECT_3_MAX1162:
 			sample_width = 16;
 			channels = rcar_gyroadc_iio_channels_3;
 			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_3);
 			break;
 		default:
 			goto err_e_inval;
 		}

 		/*
 		 * MB88101 is special in that it's only a single chip taking
 		 * up all the CHS lines. Thus, the DT binding is also special
 		 * and has no reg property. If we run into such ADC, handle
 		 * it here.
 		 */
 		if (childmode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) {
 			reg = 0;
 		} else {
 			ret = of_property_read_u32(child, "reg", &reg);
 			if (ret) {
 				dev_err(dev,
 					"Failed to get child reg property of ADC \"%pOFn\".\n",
 					child);
 				goto err_of_node_put;
 			}

 			/* Channel number is too high. */
 			if (reg >= num_channels) {
 				dev_err(dev,
 					"Only %i channels supported with %pOFn, but reg = <%i>.\n",
 					num_channels, child, reg);
 				goto err_e_inval;
 			}
 		}

 		/* Child node selected different mode than the rest. */
 		if (!first && (adcmode != childmode)) {
 			dev_err(dev,
 				"Channel %i uses different ADC mode than the rest.\n",
 				reg);
 			goto err_e_inval;
 		}

 		/* Channel is valid, grab the regulator. */
 		dev->of_node = child;
 		vref = devm_regulator_get(dev, "vref");
 		dev->of_node = np;
 		if (IS_ERR(vref)) {
 			dev_dbg(dev, "Channel %i 'vref' supply not connected.\n",
 				reg);
 			ret = PTR_ERR(vref);
 			goto err_of_node_put;
 		}

 		priv->vref[reg] = vref;

 		if (!first)
 			continue;

 		/* First child node which passed sanity tests. */
 		adcmode = childmode;
 		first = 0;

 		priv->num_channels = num_channels;
 		priv->mode = childmode;
 		priv->sample_width = sample_width;

 		indio_dev->channels = channels;
 		indio_dev->num_channels = num_channels;

 		/*
 		 * MB88101 is special and we only have one such device
 		 * attached to the GyroADC at a time, so if we found it,
 		 * we can stop parsing here.
 		 */
 		if (childmode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) {
 			of_node_put(child);
 			break;
 		}
 	}

 	if (first) {
 		dev_err(dev, "No valid ADC channels found, aborting.\n");
 		return -EINVAL;
 	}

 	return 0;

 err_e_inval:
 	ret = -EINVAL;
 err_of_node_put:
 	of_node_put(child);
 	return ret;
 }

 static void rcar_gyroadc_deinit_supplies(struct iio_dev *indio_dev)
 {
 	struct rcar_gyroadc *priv = iio_priv(indio_dev);
 	unsigned int i;

 	for (i = 0; i < priv->num_channels; i++) {
 		if (!priv->vref[i])
 			continue;

 		regulator_disable(priv->vref[i]);
 	}
 }

 static int rcar_gyroadc_init_supplies(struct iio_dev *indio_dev)
 {
 	struct rcar_gyroadc *priv = iio_priv(indio_dev);
 	struct device *dev = priv->dev;
 	unsigned int i;
 	int ret;

 	for (i = 0; i < priv->num_channels; i++) {
 		if (!priv->vref[i])
 			continue;

 		ret = regulator_enable(priv->vref[i]);
 		if (ret) {
 			dev_err(dev, "Failed to enable regulator %i (ret=%i)\n",
 				i, ret);
 			goto err;
 		}
 	}

 	return 0;

 err:
 	rcar_gyroadc_deinit_supplies(indio_dev);
 	return ret;
 }

 static int rcar_gyroadc_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct rcar_gyroadc *priv;
 	struct iio_dev *indio_dev;
 	int ret;

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

 	priv = iio_priv(indio_dev);
 	priv->dev = dev;

 	priv->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(priv->regs))
 		return PTR_ERR(priv->regs);

 	priv->clk = devm_clk_get(dev, "fck");
 	if (IS_ERR(priv->clk))
 		return dev_err_probe(dev, PTR_ERR(priv->clk),
 				     "Failed to get IF clock\n");

 	ret = rcar_gyroadc_parse_subdevs(indio_dev);
 	if (ret)
 		return ret;

 	ret = rcar_gyroadc_init_supplies(indio_dev);
 	if (ret)
 		return ret;

 	priv->model = (enum rcar_gyroadc_model)
 		of_device_get_match_data(&pdev->dev);

 	platform_set_drvdata(pdev, indio_dev);

 	indio_dev->name = DRIVER_NAME;
 	indio_dev->info = &rcar_gyroadc_iio_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;

 	ret = clk_prepare_enable(priv->clk);
 	if (ret) {
 		dev_err(dev, "Could not prepare or enable the IF clock.\n");
 		goto err_clk_if_enable;
 	}

 	pm_runtime_set_autosuspend_delay(dev, RCAR_GYROADC_RUNTIME_PM_DELAY_MS);
 	pm_runtime_use_autosuspend(dev);
 	pm_runtime_enable(dev);

 	ret = pm_runtime_resume_and_get(dev);
 	if (ret)
 		goto err_power_up;

 	rcar_gyroadc_hw_init(priv);
 	rcar_gyroadc_hw_start(priv);

 	ret = iio_device_register(indio_dev);
 	if (ret) {
 		dev_err(dev, "Couldn't register IIO device.\n");
 		goto err_iio_device_register;
 	}

 	pm_runtime_put_sync(dev);

 	return 0;

 err_iio_device_register:
 	rcar_gyroadc_hw_stop(priv);
 	pm_runtime_put_sync(dev);
 err_power_up:
 	pm_runtime_disable(dev);
 	pm_runtime_set_suspended(dev);
 	clk_disable_unprepare(priv->clk);
 err_clk_if_enable:
 	rcar_gyroadc_deinit_supplies(indio_dev);

 	return ret;
 }

 static int rcar_gyroadc_remove(struct platform_device *pdev)
 {
 	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 	struct rcar_gyroadc *priv = iio_priv(indio_dev);
 	struct device *dev = priv->dev;

 	iio_device_unregister(indio_dev);
 	pm_runtime_get_sync(dev);
 	rcar_gyroadc_hw_stop(priv);
 	pm_runtime_put_sync(dev);
 	pm_runtime_disable(dev);
 	pm_runtime_set_suspended(dev);
 	clk_disable_unprepare(priv->clk);
 	rcar_gyroadc_deinit_supplies(indio_dev);

 	return 0;
 }

 #if defined(CONFIG_PM)
 static int rcar_gyroadc_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct rcar_gyroadc *priv = iio_priv(indio_dev);

 	rcar_gyroadc_hw_stop(priv);

 	return 0;
 }

 static int rcar_gyroadc_resume(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct rcar_gyroadc *priv = iio_priv(indio_dev);

 	rcar_gyroadc_hw_start(priv);

 	return 0;
 }
 #endif

 static const struct dev_pm_ops rcar_gyroadc_pm_ops = {
 	SET_RUNTIME_PM_OPS(rcar_gyroadc_suspend, rcar_gyroadc_resume, NULL)
 };

 static struct platform_driver rcar_gyroadc_driver = {
 	.probe          = rcar_gyroadc_probe,
 	.remove         = rcar_gyroadc_remove,
 	.driver         = {
 		.name		= DRIVER_NAME,
 		.of_match_table	= rcar_gyroadc_match,
 		.pm		= &rcar_gyroadc_pm_ops,
 	},
 };

 module_platform_driver(rcar_gyroadc_driver);

 MODULE_AUTHOR("Marek Vasut <marek.vasut@gmail.com>");
 MODULE_DESCRIPTION("Renesas R-Car GyroADC driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Renesas R-Car GyroADC driver
	*
	* Copyright 2016 Marek Vasut <marek.vasut@gmail.com>
	*/

	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/delay.h>
	#include <linux/kernel.h>
	#include <linux/slab.h>
	#include <linux/io.h>
	#include <linux/clk.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/pm_runtime.h>

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

	#define DRIVER_NAME "rcar-gyroadc"

	/* GyroADC registers. */
	#define RCAR_GYROADC_MODE_SELECT 0x00
	#define RCAR_GYROADC_MODE_SELECT_1_MB88101A 0x0
	#define RCAR_GYROADC_MODE_SELECT_2_ADCS7476 0x1
	#define RCAR_GYROADC_MODE_SELECT_3_MAX1162 0x3

	#define RCAR_GYROADC_START_STOP 0x04
	#define RCAR_GYROADC_START_STOP_START BIT(0)

	#define RCAR_GYROADC_CLOCK_LENGTH 0x08
	#define RCAR_GYROADC_1_25MS_LENGTH 0x0c

	#define RCAR_GYROADC_REALTIME_DATA(ch) (0x10 + ((ch) * 4))
	#define RCAR_GYROADC_100MS_ADDED_DATA(ch) (0x30 + ((ch) * 4))
	#define RCAR_GYROADC_10MS_AVG_DATA(ch) (0x50 + ((ch) * 4))

	#define RCAR_GYROADC_FIFO_STATUS 0x70
	#define RCAR_GYROADC_FIFO_STATUS_EMPTY(ch) BIT(0 + (4 * (ch)))
	#define RCAR_GYROADC_FIFO_STATUS_FULL(ch) BIT(1 + (4 * (ch)))
	#define RCAR_GYROADC_FIFO_STATUS_ERROR(ch) BIT(2 + (4 * (ch)))

	#define RCAR_GYROADC_INTR 0x74
	#define RCAR_GYROADC_INTR_INT BIT(0)

	#define RCAR_GYROADC_INTENR 0x78
	#define RCAR_GYROADC_INTENR_INTEN BIT(0)

	#define RCAR_GYROADC_SAMPLE_RATE 800 /* Hz */

	#define RCAR_GYROADC_RUNTIME_PM_DELAY_MS 2000

	enum rcar_gyroadc_model {
	RCAR_GYROADC_MODEL_DEFAULT,
	RCAR_GYROADC_MODEL_R8A7792,
	};

	struct rcar_gyroadc {
	struct device *dev;
	void __iomem *regs;
	struct clk *clk;
	struct regulator *vref[8];
	unsigned int num_channels;
	enum rcar_gyroadc_model model;
	unsigned int mode;
	unsigned int sample_width;
	};

	static void rcar_gyroadc_hw_init(struct rcar_gyroadc *priv)
	{
	const unsigned long clk_mhz = clk_get_rate(priv->clk) / 1000000;
	const unsigned long clk_mul =
	(priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) ? 10 : 5;
	unsigned long clk_len = clk_mhz * clk_mul;

	/*
	* According to the R-Car Gen2 datasheet Rev. 1.01, Sept 08 2014,
	* page 77-7, clock length must be even number. If it's odd number,
	* add one.
	*/
	if (clk_len & 1)
	clk_len++;

	/* Stop the GyroADC. */
	writel(0, priv->regs + RCAR_GYROADC_START_STOP);

	/* Disable IRQ on V2H. */
	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
	writel(0, priv->regs + RCAR_GYROADC_INTENR);

	/* Set mode and timing. */
	writel(priv->mode, priv->regs + RCAR_GYROADC_MODE_SELECT);
	writel(clk_len, priv->regs + RCAR_GYROADC_CLOCK_LENGTH);
	writel(clk_mhz * 1250, priv->regs + RCAR_GYROADC_1_25MS_LENGTH);
	}

	static void rcar_gyroadc_hw_start(struct rcar_gyroadc *priv)
	{
	/* Start sampling. */
	writel(RCAR_GYROADC_START_STOP_START,
	priv->regs + RCAR_GYROADC_START_STOP);

	/*
	* Wait for the first conversion to complete. This is longer than
	* the 1.25 mS in the datasheet because 1.25 mS is not enough for
	* the hardware to deliver the first sample and the hardware does
	* then return zeroes instead of valid data.
	*/
	mdelay(3);
	}

	static void rcar_gyroadc_hw_stop(struct rcar_gyroadc *priv)
	{
	/* Stop the GyroADC. */
	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
	}

	#define RCAR_GYROADC_CHAN(_idx) { \
	.type = IIO_VOLTAGE, \
	.indexed = 1, \
	.channel = (_idx), \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \| \
	BIT(IIO_CHAN_INFO_SCALE), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
	}

	static const struct iio_chan_spec rcar_gyroadc_iio_channels_1[] = {
	RCAR_GYROADC_CHAN(0),
	RCAR_GYROADC_CHAN(1),
	RCAR_GYROADC_CHAN(2),
	RCAR_GYROADC_CHAN(3),
	};

	static const struct iio_chan_spec rcar_gyroadc_iio_channels_2[] = {
	RCAR_GYROADC_CHAN(0),
	RCAR_GYROADC_CHAN(1),
	RCAR_GYROADC_CHAN(2),
	RCAR_GYROADC_CHAN(3),
	RCAR_GYROADC_CHAN(4),
	RCAR_GYROADC_CHAN(5),
	RCAR_GYROADC_CHAN(6),
	RCAR_GYROADC_CHAN(7),
	};

	static const struct iio_chan_spec rcar_gyroadc_iio_channels_3[] = {
	RCAR_GYROADC_CHAN(0),
	RCAR_GYROADC_CHAN(1),
	RCAR_GYROADC_CHAN(2),
	RCAR_GYROADC_CHAN(3),
	RCAR_GYROADC_CHAN(4),
	RCAR_GYROADC_CHAN(5),
	RCAR_GYROADC_CHAN(6),
	RCAR_GYROADC_CHAN(7),
	};

	static int rcar_gyroadc_set_power(struct rcar_gyroadc *priv, bool on)
	{
	struct device *dev = priv->dev;

	if (on) {
	return pm_runtime_resume_and_get(dev);
	} else {
	pm_runtime_mark_last_busy(dev);
	return pm_runtime_put_autosuspend(dev);
	}
	}

	static int rcar_gyroadc_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct rcar_gyroadc *priv = iio_priv(indio_dev);
	struct regulator *consumer;
	unsigned int datareg = RCAR_GYROADC_REALTIME_DATA(chan->channel);
	unsigned int vref;
	int ret;

	/*
	* MB88101 is special in that it has only single regulator for
	* all four channels.
	*/
	if (priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A)
	consumer = priv->vref[0];
	else
	consumer = priv->vref[chan->channel];

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	if (chan->type != IIO_VOLTAGE)
	return -EINVAL;

	/* Channel not connected. */
	if (!consumer)
	return -EINVAL;

	ret = iio_device_claim_direct_mode(indio_dev);
	if (ret)
	return ret;

	ret = rcar_gyroadc_set_power(priv, true);
	if (ret < 0) {
	iio_device_release_direct_mode(indio_dev);
	return ret;
	}

	*val = readl(priv->regs + datareg);
	*val &= BIT(priv->sample_width) - 1;

	ret = rcar_gyroadc_set_power(priv, false);
	iio_device_release_direct_mode(indio_dev);
	if (ret < 0)
	return ret;

	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	/* Channel not connected. */
	if (!consumer)
	return -EINVAL;

	vref = regulator_get_voltage(consumer);
	*val = vref / 1000;
	*val2 = 1 << priv->sample_width;

	return IIO_VAL_FRACTIONAL;
	case IIO_CHAN_INFO_SAMP_FREQ:
	*val = RCAR_GYROADC_SAMPLE_RATE;

	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}
	}

	static int rcar_gyroadc_reg_access(struct iio_dev *indio_dev,
	unsigned int reg, unsigned int writeval,
	unsigned int *readval)
	{
	struct rcar_gyroadc *priv = iio_priv(indio_dev);
	unsigned int maxreg = RCAR_GYROADC_FIFO_STATUS;

	if (readval == NULL)
	return -EINVAL;

	if (reg % 4)
	return -EINVAL;

	/* Handle the V2H case with extra interrupt block. */
	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
	maxreg = RCAR_GYROADC_INTENR;

	if (reg > maxreg)
	return -EINVAL;

	*readval = readl(priv->regs + reg);

	return 0;
	}

	static const struct iio_info rcar_gyroadc_iio_info = {
	.read_raw = rcar_gyroadc_read_raw,
	.debugfs_reg_access = rcar_gyroadc_reg_access,
	};

	static const struct of_device_id rcar_gyroadc_match[] = {
	{
	/* R-Car compatible GyroADC */
	.compatible = "renesas,rcar-gyroadc",
	.data = (void *)RCAR_GYROADC_MODEL_DEFAULT,
	}, {
	/* R-Car V2H specialty with interrupt registers. */
	.compatible = "renesas,r8a7792-gyroadc",
	.data = (void *)RCAR_GYROADC_MODEL_R8A7792,
	}, {
	/* sentinel */
	}
	};

	MODULE_DEVICE_TABLE(of, rcar_gyroadc_match);

	static const struct of_device_id rcar_gyroadc_child_match[] = {
	/* Mode 1 ADCs */
	{
	.compatible = "fujitsu,mb88101a",
	.data = (void *)RCAR_GYROADC_MODE_SELECT_1_MB88101A,
	},
	/* Mode 2 ADCs */
	{
	.compatible = "ti,adcs7476",
	.data = (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
	}, {
	.compatible = "ti,adc121",
	.data = (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
	}, {
	.compatible = "adi,ad7476",
	.data = (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
	},
	/* Mode 3 ADCs */
	{
	.compatible = "maxim,max1162",
	.data = (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
	}, {
	.compatible = "maxim,max11100",
	.data = (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
	},
	{ /* sentinel */ }
	};

	static int rcar_gyroadc_parse_subdevs(struct iio_dev *indio_dev)
	{
	const struct of_device_id *of_id;
	const struct iio_chan_spec *channels;
	struct rcar_gyroadc *priv = iio_priv(indio_dev);
	struct device *dev = priv->dev;
	struct device_node *np = dev->of_node;
	struct device_node *child;
	struct regulator *vref;
	unsigned int reg;
	unsigned int adcmode = -1, childmode;
	unsigned int sample_width;
	unsigned int num_channels;
	int ret, first = 1;

	for_each_child_of_node(np, child) {
	of_id = of_match_node(rcar_gyroadc_child_match, child);
	if (!of_id) {
	dev_err(dev, "Ignoring unsupported ADC \"%pOFn\".",
	child);
	continue;
	}

	childmode = (uintptr_t)of_id->data;
	switch (childmode) {
	case RCAR_GYROADC_MODE_SELECT_1_MB88101A:
	sample_width = 12;
	channels = rcar_gyroadc_iio_channels_1;
	num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_1);
	break;
	case RCAR_GYROADC_MODE_SELECT_2_ADCS7476:
	sample_width = 15;
	channels = rcar_gyroadc_iio_channels_2;
	num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_2);
	break;
	case RCAR_GYROADC_MODE_SELECT_3_MAX1162:
	sample_width = 16;
	channels = rcar_gyroadc_iio_channels_3;
	num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_3);
	break;
	default:
	goto err_e_inval;
	}

	/*
	* MB88101 is special in that it's only a single chip taking
	* up all the CHS lines. Thus, the DT binding is also special
	* and has no reg property. If we run into such ADC, handle
	* it here.
	*/
	if (childmode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) {
	reg = 0;
	} else {
	ret = of_property_read_u32(child, "reg", &reg);
	if (ret) {
	dev_err(dev,
	"Failed to get child reg property of ADC \"%pOFn\".\n",
	child);
	goto err_of_node_put;
	}

	/* Channel number is too high. */
	if (reg >= num_channels) {
	dev_err(dev,
	"Only %i channels supported with %pOFn, but reg = <%i>.\n",
	num_channels, child, reg);
	goto err_e_inval;
	}
	}

	/* Child node selected different mode than the rest. */
	if (!first && (adcmode != childmode)) {
	dev_err(dev,
	"Channel %i uses different ADC mode than the rest.\n",
	reg);
	goto err_e_inval;
	}

	/* Channel is valid, grab the regulator. */
	dev->of_node = child;
	vref = devm_regulator_get(dev, "vref");
	dev->of_node = np;
	if (IS_ERR(vref)) {
	dev_dbg(dev, "Channel %i 'vref' supply not connected.\n",
	reg);
	ret = PTR_ERR(vref);
	goto err_of_node_put;
	}

	priv->vref[reg] = vref;

	if (!first)
	continue;

	/* First child node which passed sanity tests. */
	adcmode = childmode;
	first = 0;

	priv->num_channels = num_channels;
	priv->mode = childmode;
	priv->sample_width = sample_width;

	indio_dev->channels = channels;
	indio_dev->num_channels = num_channels;

	/*
	* MB88101 is special and we only have one such device
	* attached to the GyroADC at a time, so if we found it,
	* we can stop parsing here.
	*/
	if (childmode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) {
	of_node_put(child);
	break;
	}
	}

	if (first) {
	dev_err(dev, "No valid ADC channels found, aborting.\n");
	return -EINVAL;
	}

	return 0;

	err_e_inval:
	ret = -EINVAL;
	err_of_node_put:
	of_node_put(child);
	return ret;
	}

	static void rcar_gyroadc_deinit_supplies(struct iio_dev *indio_dev)
	{
	struct rcar_gyroadc *priv = iio_priv(indio_dev);
	unsigned int i;

	for (i = 0; i < priv->num_channels; i++) {
	if (!priv->vref[i])
	continue;

	regulator_disable(priv->vref[i]);
	}
	}

	static int rcar_gyroadc_init_supplies(struct iio_dev *indio_dev)
	{
	struct rcar_gyroadc *priv = iio_priv(indio_dev);
	struct device *dev = priv->dev;
	unsigned int i;
	int ret;

	for (i = 0; i < priv->num_channels; i++) {
	if (!priv->vref[i])
	continue;

	ret = regulator_enable(priv->vref[i]);
	if (ret) {
	dev_err(dev, "Failed to enable regulator %i (ret=%i)\n",
	i, ret);
	goto err;
	}
	}

	return 0;

	err:
	rcar_gyroadc_deinit_supplies(indio_dev);
	return ret;
	}

	static int rcar_gyroadc_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct rcar_gyroadc *priv;
	struct iio_dev *indio_dev;
	int ret;

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

	priv = iio_priv(indio_dev);
	priv->dev = dev;

	priv->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(priv->regs))
	return PTR_ERR(priv->regs);

	priv->clk = devm_clk_get(dev, "fck");
	if (IS_ERR(priv->clk))
	return dev_err_probe(dev, PTR_ERR(priv->clk),
	"Failed to get IF clock\n");

	ret = rcar_gyroadc_parse_subdevs(indio_dev);
	if (ret)
	return ret;

	ret = rcar_gyroadc_init_supplies(indio_dev);
	if (ret)
	return ret;

	priv->model = (enum rcar_gyroadc_model)
	of_device_get_match_data(&pdev->dev);

	platform_set_drvdata(pdev, indio_dev);

	indio_dev->name = DRIVER_NAME;
	indio_dev->info = &rcar_gyroadc_iio_info;
	indio_dev->modes = INDIO_DIRECT_MODE;

	ret = clk_prepare_enable(priv->clk);
	if (ret) {
	dev_err(dev, "Could not prepare or enable the IF clock.\n");
	goto err_clk_if_enable;
	}

	pm_runtime_set_autosuspend_delay(dev, RCAR_GYROADC_RUNTIME_PM_DELAY_MS);
	pm_runtime_use_autosuspend(dev);
	pm_runtime_enable(dev);

	ret = pm_runtime_resume_and_get(dev);
	if (ret)
	goto err_power_up;

	rcar_gyroadc_hw_init(priv);
	rcar_gyroadc_hw_start(priv);

	ret = iio_device_register(indio_dev);
	if (ret) {
	dev_err(dev, "Couldn't register IIO device.\n");
	goto err_iio_device_register;
	}

	pm_runtime_put_sync(dev);

	return 0;

	err_iio_device_register:
	rcar_gyroadc_hw_stop(priv);
	pm_runtime_put_sync(dev);
	err_power_up:
	pm_runtime_disable(dev);
	pm_runtime_set_suspended(dev);
	clk_disable_unprepare(priv->clk);
	err_clk_if_enable:
	rcar_gyroadc_deinit_supplies(indio_dev);

	return ret;
	}

	static int rcar_gyroadc_remove(struct platform_device *pdev)
	{
	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
	struct rcar_gyroadc *priv = iio_priv(indio_dev);
	struct device *dev = priv->dev;

	iio_device_unregister(indio_dev);
	pm_runtime_get_sync(dev);
	rcar_gyroadc_hw_stop(priv);
	pm_runtime_put_sync(dev);
	pm_runtime_disable(dev);
	pm_runtime_set_suspended(dev);
	clk_disable_unprepare(priv->clk);
	rcar_gyroadc_deinit_supplies(indio_dev);

	return 0;
	}

	#if defined(CONFIG_PM)
	static int rcar_gyroadc_suspend(struct device *dev)
	{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct rcar_gyroadc *priv = iio_priv(indio_dev);

	rcar_gyroadc_hw_stop(priv);

	return 0;
	}

	static int rcar_gyroadc_resume(struct device *dev)
	{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct rcar_gyroadc *priv = iio_priv(indio_dev);

	rcar_gyroadc_hw_start(priv);

	return 0;
	}
	#endif

	static const struct dev_pm_ops rcar_gyroadc_pm_ops = {
	SET_RUNTIME_PM_OPS(rcar_gyroadc_suspend, rcar_gyroadc_resume, NULL)
	};

	static struct platform_driver rcar_gyroadc_driver = {
	.probe = rcar_gyroadc_probe,
	.remove = rcar_gyroadc_remove,
	.driver = {
	.name = DRIVER_NAME,
	.of_match_table = rcar_gyroadc_match,
	.pm = &rcar_gyroadc_pm_ops,
	},
	};

	module_platform_driver(rcar_gyroadc_driver);

	MODULE_AUTHOR("Marek Vasut <marek.vasut@gmail.com>");
	MODULE_DESCRIPTION("Renesas R-Car GyroADC driver");
	MODULE_LICENSE("GPL");