drivers/iio/accel/cros_ec_accel_legacy.c - linux-mtk - Git at Google

 /*
  * Driver for older Chrome OS EC accelerometer
  *
  * Copyright 2017 Google, Inc
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
  * may be copied, distributed, and modified under those terms.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * This driver uses the memory mapper cros-ec interface to communicate
  * with the Chrome OS EC about accelerometer data.
  * Accelerometer access is presented through iio sysfs.
  */

 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/kfifo_buf.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/kernel.h>
 #include <linux/mfd/cros_ec.h>
 #include <linux/mfd/cros_ec_commands.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/platform_device.h>

 #define DRV_NAME	"cros-ec-accel-legacy"

 /*
  * Sensor scale hard coded at 10 bits per g, computed as:
  * g / (2^10 - 1) = 0.009586168; with g = 9.80665 m.s^-2
  */
 #define ACCEL_LEGACY_NSCALE 9586168

 /* Indices for EC sensor values. */
 enum {
 	X,
 	Y,
 	Z,
 	MAX_AXIS,
 };

 /* State data for cros_ec_accel_legacy iio driver. */
 struct cros_ec_accel_legacy_state {
 	struct cros_ec_device *ec;

 	/*
 	 * Array holding data from a single capture. 2 bytes per channel
 	 * for the 3 channels plus the timestamp which is always last and
 	 * 8-bytes aligned.
 	 */
 	s16 capture_data[8];
 	s8 sign[MAX_AXIS];
 	u8 sensor_num;
 };

 static int ec_cmd_read_u8(struct cros_ec_device *ec, unsigned int offset,
 			  u8 *dest)
 {
 	return ec->cmd_readmem(ec, offset, 1, dest);
 }

 static int ec_cmd_read_u16(struct cros_ec_device *ec, unsigned int offset,
 			   u16 *dest)
 {
 	__le16 tmp;
 	int ret = ec->cmd_readmem(ec, offset, 2, &tmp);

 	*dest = le16_to_cpu(tmp);

 	return ret;
 }

 /**
  * read_ec_until_not_busy() - Read from EC status byte until it reads not busy.
  * @st: Pointer to state information for device.
  *
  * This function reads EC status until its busy bit gets cleared. It does not
  * wait indefinitely and returns -EIO if the EC status is still busy after a
  * few hundreds milliseconds.
  *
  * Return: 8-bit status if ok, -EIO on error
  */
 static int read_ec_until_not_busy(struct cros_ec_accel_legacy_state *st)
 {
 	struct cros_ec_device *ec = st->ec;
 	u8 status;
 	int attempts = 0;

 	ec_cmd_read_u8(ec, EC_MEMMAP_ACC_STATUS, &status);
 	while (status & EC_MEMMAP_ACC_STATUS_BUSY_BIT) {
 		/* Give up after enough attempts, return error. */
 		if (attempts++ >= 50)
 			return -EIO;

 		/* Small delay every so often. */
 		if (attempts % 5 == 0)
 			msleep(25);

 		ec_cmd_read_u8(ec, EC_MEMMAP_ACC_STATUS, &status);
 	}

 	return status;
 }

 /**
  * read_ec_accel_data_unsafe() - Read acceleration data from EC shared memory.
  * @st:        Pointer to state information for device.
  * @scan_mask: Bitmap of the sensor indices to scan.
  * @data:      Location to store data.
  *
  * This is the unsafe function for reading the EC data. It does not guarantee
  * that the EC will not modify the data as it is being read in.
  */
 static void read_ec_accel_data_unsafe(struct cros_ec_accel_legacy_state *st,
 				      unsigned long scan_mask, s16 *data)
 {
 	int i = 0;
 	int num_enabled = bitmap_weight(&scan_mask, MAX_AXIS);

 	/* Read all sensors enabled in scan_mask. Each value is 2 bytes. */
 	while (num_enabled--) {
 		i = find_next_bit(&scan_mask, MAX_AXIS, i);
 		ec_cmd_read_u16(st->ec,
 				EC_MEMMAP_ACC_DATA +
 				sizeof(s16) *
 				(1 + i + st->sensor_num * MAX_AXIS),
 				data);
 		*data *= st->sign[i];
 		i++;
 		data++;
 	}
 }

 /**
  * read_ec_accel_data() - Read acceleration data from EC shared memory.
  * @st:        Pointer to state information for device.
  * @scan_mask: Bitmap of the sensor indices to scan.
  * @data:      Location to store data.
  *
  * This is the safe function for reading the EC data. It guarantees that
  * the data sampled was not modified by the EC while being read.
  *
  * Return: 0 if ok, -ve on error
  */
 static int read_ec_accel_data(struct cros_ec_accel_legacy_state *st,
 			      unsigned long scan_mask, s16 *data)
 {
 	u8 samp_id = 0xff;
 	u8 status = 0;
 	int ret;
 	int attempts = 0;

 	/*
 	 * Continually read all data from EC until the status byte after
 	 * all reads reflects that the EC is not busy and the sample id
 	 * matches the sample id from before all reads. This guarantees
 	 * that data read in was not modified by the EC while reading.
 	 */
 	while ((status & (EC_MEMMAP_ACC_STATUS_BUSY_BIT |
 			  EC_MEMMAP_ACC_STATUS_SAMPLE_ID_MASK)) != samp_id) {
 		/* If we have tried to read too many times, return error. */
 		if (attempts++ >= 5)
 			return -EIO;

 		/* Read status byte until EC is not busy. */
 		ret = read_ec_until_not_busy(st);
 		if (ret < 0)
 			return ret;
 		status = ret;

 		/*
 		 * Store the current sample id so that we can compare to the
 		 * sample id after reading the data.
 		 */
 		samp_id = status & EC_MEMMAP_ACC_STATUS_SAMPLE_ID_MASK;

 		/* Read all EC data, format it, and store it into data. */
 		read_ec_accel_data_unsafe(st, scan_mask, data);

 		/* Read status byte. */
 		ec_cmd_read_u8(st->ec, EC_MEMMAP_ACC_STATUS, &status);
 	}

 	return 0;
 }

 static int cros_ec_accel_legacy_read(struct iio_dev *indio_dev,
 				     struct iio_chan_spec const *chan,
 				     int *val, int *val2, long mask)
 {
 	struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);
 	s16 data = 0;
 	int ret = IIO_VAL_INT;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		ret = read_ec_accel_data(st, (1 << chan->scan_index), &data);
 		if (ret)
 			return ret;
 		*val = data;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		*val = 0;
 		*val2 = ACCEL_LEGACY_NSCALE;
 		return IIO_VAL_INT_PLUS_NANO;
 	case IIO_CHAN_INFO_CALIBBIAS:
 		/* Calibration not supported. */
 		*val = 0;
 		return IIO_VAL_INT;
 	default:
 		return -EINVAL;
 	}
 }

 static int cros_ec_accel_legacy_write(struct iio_dev *indio_dev,
 				      struct iio_chan_spec const *chan,
 				      int val, int val2, long mask)
 {
 	/*
 	 * Do nothing but don't return an error code to allow calibration
 	 * script to work.
 	 */
 	if (mask == IIO_CHAN_INFO_CALIBBIAS)
 		return 0;

 	return -EINVAL;
 }

 static const struct iio_info cros_ec_accel_legacy_info = {
 	.read_raw = &cros_ec_accel_legacy_read,
 	.write_raw = &cros_ec_accel_legacy_write,
 };

 /**
  * cros_ec_accel_legacy_capture() - The trigger handler function
  * @irq: The interrupt number.
  * @p:   Private data - always a pointer to the poll func.
  *
  * On a trigger event occurring, if the pollfunc is attached then this
  * handler is called as a threaded interrupt (and hence may sleep). It
  * is responsible for grabbing data from the device and pushing it into
  * the associated buffer.
  *
  * Return: IRQ_HANDLED
  */
 static irqreturn_t cros_ec_accel_legacy_capture(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);

 	/* Clear capture data. */
 	memset(st->capture_data, 0, sizeof(st->capture_data));

 	/*
 	 * Read data based on which channels are enabled in scan mask. Note
 	 * that on a capture we are always reading the calibrated data.
 	 */
 	read_ec_accel_data(st, *indio_dev->active_scan_mask, st->capture_data);

 	iio_push_to_buffers_with_timestamp(indio_dev, (void *)st->capture_data,
 					   iio_get_time_ns(indio_dev));

 	/*
 	 * Tell the core we are done with this trigger and ready for the
 	 * next one.
 	 */
 	iio_trigger_notify_done(indio_dev->trig);

 	return IRQ_HANDLED;
 }

 static char *cros_ec_accel_legacy_loc_strings[] = {
 	[MOTIONSENSE_LOC_BASE] = "base",
 	[MOTIONSENSE_LOC_LID] = "lid",
 	[MOTIONSENSE_LOC_MAX] = "unknown",
 };

 static ssize_t cros_ec_accel_legacy_loc(struct iio_dev *indio_dev,
 					uintptr_t private,
 					const struct iio_chan_spec *chan,
 					char *buf)
 {
 	struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);

 	return sprintf(buf, "%s\n",
 		       cros_ec_accel_legacy_loc_strings[st->sensor_num +
 							MOTIONSENSE_LOC_BASE]);
 }

 static ssize_t cros_ec_accel_legacy_id(struct iio_dev *indio_dev,
 				       uintptr_t private,
 				       const struct iio_chan_spec *chan,
 				       char *buf)
 {
 	struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);

 	return sprintf(buf, "%d\n", st->sensor_num);
 }

 static const struct iio_chan_spec_ext_info cros_ec_accel_legacy_ext_info[] = {
 	{
 		.name = "id",
 		.shared = IIO_SHARED_BY_ALL,
 		.read = cros_ec_accel_legacy_id,
 	},
 	{
 		.name = "location",
 		.shared = IIO_SHARED_BY_ALL,
 		.read = cros_ec_accel_legacy_loc,
 	},
 	{ }
 };

 #define CROS_EC_ACCEL_LEGACY_CHAN(_axis)				\
 	{								\
 		.type = IIO_ACCEL,					\
 		.channel2 = IIO_MOD_X + (_axis),			\
 		.modified = 1,					        \
 		.info_mask_separate =					\
 			BIT(IIO_CHAN_INFO_RAW) |			\
 			BIT(IIO_CHAN_INFO_CALIBBIAS),			\
 		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SCALE),	\
 		.ext_info = cros_ec_accel_legacy_ext_info,		\
 		.scan_type = {						\
 			.sign = 's',					\
 			.realbits = 16,					\
 			.storagebits = 16,				\
 		},							\
 	}								\

 static struct iio_chan_spec ec_accel_channels[] = {
 	CROS_EC_ACCEL_LEGACY_CHAN(X),
 	CROS_EC_ACCEL_LEGACY_CHAN(Y),
 	CROS_EC_ACCEL_LEGACY_CHAN(Z),
 	IIO_CHAN_SOFT_TIMESTAMP(MAX_AXIS)
 };

 static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct cros_ec_dev *ec = dev_get_drvdata(dev->parent);
 	struct cros_ec_sensor_platform *sensor_platform = dev_get_platdata(dev);
 	struct iio_dev *indio_dev;
 	struct cros_ec_accel_legacy_state *state;
 	int ret, i;

 	if (!ec || !ec->ec_dev) {
 		dev_warn(&pdev->dev, "No EC device found.\n");
 		return -EINVAL;
 	}

 	if (!ec->ec_dev->cmd_readmem) {
 		dev_warn(&pdev->dev, "EC does not support direct reads.\n");
 		return -EINVAL;
 	}

 	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*state));
 	if (!indio_dev)
 		return -ENOMEM;

 	platform_set_drvdata(pdev, indio_dev);
 	state = iio_priv(indio_dev);
 	state->ec = ec->ec_dev;
 	state->sensor_num = sensor_platform->sensor_num;

 	indio_dev->dev.parent = dev;
 	indio_dev->name = pdev->name;
 	indio_dev->channels = ec_accel_channels;
 	/*
 	 * Present the channel using HTML5 standard:
 	 * need to invert X and Y and invert some lid axis.
 	 */
 	for (i = X ; i < MAX_AXIS; i++) {
 		switch (i) {
 		case X:
 			ec_accel_channels[X].scan_index = Y;
 		case Y:
 			ec_accel_channels[Y].scan_index = X;
 		case Z:
 			ec_accel_channels[Z].scan_index = Z;
 		}
 		if (state->sensor_num == MOTIONSENSE_LOC_LID && i != Y)
 			state->sign[i] = -1;
 		else
 			state->sign[i] = 1;
 	}
 	indio_dev->num_channels = ARRAY_SIZE(ec_accel_channels);
 	indio_dev->dev.parent = &pdev->dev;
 	indio_dev->info = &cros_ec_accel_legacy_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;

 	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
 					      cros_ec_accel_legacy_capture,
 					      NULL);
 	if (ret)
 		return ret;

 	return devm_iio_device_register(dev, indio_dev);
 }

 static struct platform_driver cros_ec_accel_platform_driver = {
 	.driver = {
 		.name	= DRV_NAME,
 	},
 	.probe		= cros_ec_accel_legacy_probe,
 };
 module_platform_driver(cros_ec_accel_platform_driver);

 MODULE_DESCRIPTION("ChromeOS EC legacy accelerometer driver");
 MODULE_AUTHOR("Gwendal Grignou <gwendal@chromium.org>");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:" DRV_NAME);
	/*
	* Driver for older Chrome OS EC accelerometer
	*
	* Copyright 2017 Google, Inc
	*
	* This software is licensed under the terms of the GNU General Public
	* License version 2, as published by the Free Software Foundation, and
	* may be copied, distributed, and modified under those terms.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* This driver uses the memory mapper cros-ec interface to communicate
	* with the Chrome OS EC about accelerometer data.
	* Accelerometer access is presented through iio sysfs.
	*/

	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/iio/buffer.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/kfifo_buf.h>
	#include <linux/iio/trigger_consumer.h>
	#include <linux/iio/triggered_buffer.h>
	#include <linux/kernel.h>
	#include <linux/mfd/cros_ec.h>
	#include <linux/mfd/cros_ec_commands.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/sysfs.h>
	#include <linux/platform_device.h>

	#define DRV_NAME "cros-ec-accel-legacy"

	/*
	* Sensor scale hard coded at 10 bits per g, computed as:
	* g / (2^10 - 1) = 0.009586168; with g = 9.80665 m.s^-2
	*/
	#define ACCEL_LEGACY_NSCALE 9586168

	/* Indices for EC sensor values. */
	enum {
	X,
	Y,
	Z,
	MAX_AXIS,
	};

	/* State data for cros_ec_accel_legacy iio driver. */
	struct cros_ec_accel_legacy_state {
	struct cros_ec_device *ec;

	/*
	* Array holding data from a single capture. 2 bytes per channel
	* for the 3 channels plus the timestamp which is always last and
	* 8-bytes aligned.
	*/
	s16 capture_data[8];
	s8 sign[MAX_AXIS];
	u8 sensor_num;
	};

	static int ec_cmd_read_u8(struct cros_ec_device *ec, unsigned int offset,
	u8 *dest)
	{
	return ec->cmd_readmem(ec, offset, 1, dest);
	}

	static int ec_cmd_read_u16(struct cros_ec_device *ec, unsigned int offset,
	u16 *dest)
	{
	__le16 tmp;
	int ret = ec->cmd_readmem(ec, offset, 2, &tmp);

	*dest = le16_to_cpu(tmp);

	return ret;
	}

	/**
	* read_ec_until_not_busy() - Read from EC status byte until it reads not busy.
	* @st: Pointer to state information for device.
	*
	* This function reads EC status until its busy bit gets cleared. It does not
	* wait indefinitely and returns -EIO if the EC status is still busy after a
	* few hundreds milliseconds.
	*
	* Return: 8-bit status if ok, -EIO on error
	*/
	static int read_ec_until_not_busy(struct cros_ec_accel_legacy_state *st)
	{
	struct cros_ec_device *ec = st->ec;
	u8 status;
	int attempts = 0;

	ec_cmd_read_u8(ec, EC_MEMMAP_ACC_STATUS, &status);
	while (status & EC_MEMMAP_ACC_STATUS_BUSY_BIT) {
	/* Give up after enough attempts, return error. */
	if (attempts++ >= 50)
	return -EIO;

	/* Small delay every so often. */
	if (attempts % 5 == 0)
	msleep(25);

	ec_cmd_read_u8(ec, EC_MEMMAP_ACC_STATUS, &status);
	}

	return status;
	}

	/**
	* read_ec_accel_data_unsafe() - Read acceleration data from EC shared memory.
	* @st: Pointer to state information for device.
	* @scan_mask: Bitmap of the sensor indices to scan.
	* @data: Location to store data.
	*
	* This is the unsafe function for reading the EC data. It does not guarantee
	* that the EC will not modify the data as it is being read in.
	*/
	static void read_ec_accel_data_unsafe(struct cros_ec_accel_legacy_state *st,
	unsigned long scan_mask, s16 *data)
	{
	int i = 0;
	int num_enabled = bitmap_weight(&scan_mask, MAX_AXIS);

	/* Read all sensors enabled in scan_mask. Each value is 2 bytes. */
	while (num_enabled--) {
	i = find_next_bit(&scan_mask, MAX_AXIS, i);
	ec_cmd_read_u16(st->ec,
	EC_MEMMAP_ACC_DATA +
	sizeof(s16) *
	(1 + i + st->sensor_num * MAX_AXIS),
	data);
	data = st->sign[i];
	i++;
	data++;
	}
	}

	/**
	* read_ec_accel_data() - Read acceleration data from EC shared memory.
	* @st: Pointer to state information for device.
	* @scan_mask: Bitmap of the sensor indices to scan.
	* @data: Location to store data.
	*
	* This is the safe function for reading the EC data. It guarantees that
	* the data sampled was not modified by the EC while being read.
	*
	* Return: 0 if ok, -ve on error
	*/
	static int read_ec_accel_data(struct cros_ec_accel_legacy_state *st,
	unsigned long scan_mask, s16 *data)
	{
	u8 samp_id = 0xff;
	u8 status = 0;
	int ret;
	int attempts = 0;

	/*
	* Continually read all data from EC until the status byte after
	* all reads reflects that the EC is not busy and the sample id
	* matches the sample id from before all reads. This guarantees
	* that data read in was not modified by the EC while reading.
	*/
	while ((status & (EC_MEMMAP_ACC_STATUS_BUSY_BIT \|
	EC_MEMMAP_ACC_STATUS_SAMPLE_ID_MASK)) != samp_id) {
	/* If we have tried to read too many times, return error. */
	if (attempts++ >= 5)
	return -EIO;

	/* Read status byte until EC is not busy. */
	ret = read_ec_until_not_busy(st);
	if (ret < 0)
	return ret;
	status = ret;

	/*
	* Store the current sample id so that we can compare to the
	* sample id after reading the data.
	*/
	samp_id = status & EC_MEMMAP_ACC_STATUS_SAMPLE_ID_MASK;

	/* Read all EC data, format it, and store it into data. */
	read_ec_accel_data_unsafe(st, scan_mask, data);

	/* Read status byte. */
	ec_cmd_read_u8(st->ec, EC_MEMMAP_ACC_STATUS, &status);
	}

	return 0;
	}

	static int cros_ec_accel_legacy_read(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);
	s16 data = 0;
	int ret = IIO_VAL_INT;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	ret = read_ec_accel_data(st, (1 << chan->scan_index), &data);
	if (ret)
	return ret;
	*val = data;
	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	*val = 0;
	*val2 = ACCEL_LEGACY_NSCALE;
	return IIO_VAL_INT_PLUS_NANO;
	case IIO_CHAN_INFO_CALIBBIAS:
	/* Calibration not supported. */
	*val = 0;
	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}
	}

	static int cros_ec_accel_legacy_write(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	/*
	* Do nothing but don't return an error code to allow calibration
	* script to work.
	*/
	if (mask == IIO_CHAN_INFO_CALIBBIAS)
	return 0;

	return -EINVAL;
	}

	static const struct iio_info cros_ec_accel_legacy_info = {
	.read_raw = &cros_ec_accel_legacy_read,
	.write_raw = &cros_ec_accel_legacy_write,
	};

	/**
	* cros_ec_accel_legacy_capture() - The trigger handler function
	* @irq: The interrupt number.
	* @p: Private data - always a pointer to the poll func.
	*
	* On a trigger event occurring, if the pollfunc is attached then this
	* handler is called as a threaded interrupt (and hence may sleep). It
	* is responsible for grabbing data from the device and pushing it into
	* the associated buffer.
	*
	* Return: IRQ_HANDLED
	*/
	static irqreturn_t cros_ec_accel_legacy_capture(int irq, void *p)
	{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);

	/* Clear capture data. */
	memset(st->capture_data, 0, sizeof(st->capture_data));

	/*
	* Read data based on which channels are enabled in scan mask. Note
	* that on a capture we are always reading the calibrated data.
	*/
	read_ec_accel_data(st, *indio_dev->active_scan_mask, st->capture_data);

	iio_push_to_buffers_with_timestamp(indio_dev, (void *)st->capture_data,
	iio_get_time_ns(indio_dev));

	/*
	* Tell the core we are done with this trigger and ready for the
	* next one.
	*/
	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
	}

	static char *cros_ec_accel_legacy_loc_strings[] = {
	[MOTIONSENSE_LOC_BASE] = "base",
	[MOTIONSENSE_LOC_LID] = "lid",
	[MOTIONSENSE_LOC_MAX] = "unknown",
	};

	static ssize_t cros_ec_accel_legacy_loc(struct iio_dev *indio_dev,
	uintptr_t private,
	const struct iio_chan_spec *chan,
	char *buf)
	{
	struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);

	return sprintf(buf, "%s\n",
	cros_ec_accel_legacy_loc_strings[st->sensor_num +
	MOTIONSENSE_LOC_BASE]);
	}

	static ssize_t cros_ec_accel_legacy_id(struct iio_dev *indio_dev,
	uintptr_t private,
	const struct iio_chan_spec *chan,
	char *buf)
	{
	struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);

	return sprintf(buf, "%d\n", st->sensor_num);
	}

	static const struct iio_chan_spec_ext_info cros_ec_accel_legacy_ext_info[] = {
	{
	.name = "id",
	.shared = IIO_SHARED_BY_ALL,
	.read = cros_ec_accel_legacy_id,
	},
	{
	.name = "location",
	.shared = IIO_SHARED_BY_ALL,
	.read = cros_ec_accel_legacy_loc,
	},
	{ }
	};

	#define CROS_EC_ACCEL_LEGACY_CHAN(_axis) \
	{ \
	.type = IIO_ACCEL, \
	.channel2 = IIO_MOD_X + (_axis), \
	.modified = 1, \
	.info_mask_separate = \
	BIT(IIO_CHAN_INFO_RAW) \| \
	BIT(IIO_CHAN_INFO_CALIBBIAS), \
	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SCALE), \
	.ext_info = cros_ec_accel_legacy_ext_info, \
	.scan_type = { \
	.sign = 's', \
	.realbits = 16, \
	.storagebits = 16, \
	}, \
	} \

	static struct iio_chan_spec ec_accel_channels[] = {
	CROS_EC_ACCEL_LEGACY_CHAN(X),
	CROS_EC_ACCEL_LEGACY_CHAN(Y),
	CROS_EC_ACCEL_LEGACY_CHAN(Z),
	IIO_CHAN_SOFT_TIMESTAMP(MAX_AXIS)
	};

	static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct cros_ec_dev *ec = dev_get_drvdata(dev->parent);
	struct cros_ec_sensor_platform *sensor_platform = dev_get_platdata(dev);
	struct iio_dev *indio_dev;
	struct cros_ec_accel_legacy_state *state;
	int ret, i;

	if (!ec \|\| !ec->ec_dev) {
	dev_warn(&pdev->dev, "No EC device found.\n");
	return -EINVAL;
	}

	if (!ec->ec_dev->cmd_readmem) {
	dev_warn(&pdev->dev, "EC does not support direct reads.\n");
	return -EINVAL;
	}

	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*state));
	if (!indio_dev)
	return -ENOMEM;

	platform_set_drvdata(pdev, indio_dev);
	state = iio_priv(indio_dev);
	state->ec = ec->ec_dev;
	state->sensor_num = sensor_platform->sensor_num;

	indio_dev->dev.parent = dev;
	indio_dev->name = pdev->name;
	indio_dev->channels = ec_accel_channels;
	/*
	* Present the channel using HTML5 standard:
	* need to invert X and Y and invert some lid axis.
	*/
	for (i = X ; i < MAX_AXIS; i++) {
	switch (i) {
	case X:
	ec_accel_channels[X].scan_index = Y;
	case Y:
	ec_accel_channels[Y].scan_index = X;
	case Z:
	ec_accel_channels[Z].scan_index = Z;
	}
	if (state->sensor_num == MOTIONSENSE_LOC_LID && i != Y)
	state->sign[i] = -1;
	else
	state->sign[i] = 1;
	}
	indio_dev->num_channels = ARRAY_SIZE(ec_accel_channels);
	indio_dev->dev.parent = &pdev->dev;
	indio_dev->info = &cros_ec_accel_legacy_info;
	indio_dev->modes = INDIO_DIRECT_MODE;

	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
	cros_ec_accel_legacy_capture,
	NULL);
	if (ret)
	return ret;

	return devm_iio_device_register(dev, indio_dev);
	}

	static struct platform_driver cros_ec_accel_platform_driver = {
	.driver = {
	.name = DRV_NAME,
	},
	.probe = cros_ec_accel_legacy_probe,
	};
	module_platform_driver(cros_ec_accel_platform_driver);

	MODULE_DESCRIPTION("ChromeOS EC legacy accelerometer driver");
	MODULE_AUTHOR("Gwendal Grignou <gwendal@chromium.org>");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:" DRV_NAME);