drivers/iio/accel/mma8452.c - linux - Git at Google

 /*
  * mma8452.c - Support for Freescale MMA8452Q 3-axis 12-bit accelerometer
  *
  * Copyright 2014 Peter Meerwald <pmeerw@pmeerw.net>
  *
  * This file is subject to the terms and conditions of version 2 of
  * the GNU General Public License.  See the file COPYING in the main
  * directory of this archive for more details.
  *
  * 7-bit I2C slave address 0x1c/0x1d (pin selectable)
  *
  * TODO: interrupt, thresholding, orientation / freefall events, autosleep
  */

 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/delay.h>

 #define MMA8452_STATUS 0x00
 #define MMA8452_OUT_X 0x01 /* MSB first, 12-bit  */
 #define MMA8452_OUT_Y 0x03
 #define MMA8452_OUT_Z 0x05
 #define MMA8452_WHO_AM_I 0x0d
 #define MMA8452_DATA_CFG 0x0e
 #define MMA8452_OFF_X 0x2f
 #define MMA8452_OFF_Y 0x30
 #define MMA8452_OFF_Z 0x31
 #define MMA8452_CTRL_REG1 0x2a
 #define MMA8452_CTRL_REG2 0x2b

 #define MMA8452_STATUS_DRDY (BIT(2) | BIT(1) | BIT(0))

 #define MMA8452_CTRL_DR_MASK (BIT(5) | BIT(4) | BIT(3))
 #define MMA8452_CTRL_DR_SHIFT 3
 #define MMA8452_CTRL_DR_DEFAULT 0x4 /* 50 Hz sample frequency */
 #define MMA8452_CTRL_ACTIVE BIT(0)

 #define MMA8452_DATA_CFG_FS_MASK (BIT(1) | BIT(0))
 #define MMA8452_DATA_CFG_FS_2G 0
 #define MMA8452_DATA_CFG_FS_4G 1
 #define MMA8452_DATA_CFG_FS_8G 2

 #define MMA8452_DEVICE_ID 0x2a

 struct mma8452_data {
 	struct i2c_client *client;
 	struct mutex lock;
 	u8 ctrl_reg1;
 	u8 data_cfg;
 };

 static int mma8452_drdy(struct mma8452_data *data)
 {
 	int tries = 150;

 	while (tries-- > 0) {
 		int ret = i2c_smbus_read_byte_data(data->client,
 			MMA8452_STATUS);
 		if (ret < 0)
 			return ret;
 		if ((ret & MMA8452_STATUS_DRDY) == MMA8452_STATUS_DRDY)
 			return 0;
 		msleep(20);
 	}

 	dev_err(&data->client->dev, "data not ready\n");
 	return -EIO;
 }

 static int mma8452_read(struct mma8452_data *data, __be16 buf[3])
 {
 	int ret = mma8452_drdy(data);
 	if (ret < 0)
 		return ret;
 	return i2c_smbus_read_i2c_block_data(data->client,
 		MMA8452_OUT_X, 3 * sizeof(__be16), (u8 *) buf);
 }

 static ssize_t mma8452_show_int_plus_micros(char *buf,
 	const int (*vals)[2], int n)
 {
 	size_t len = 0;

 	while (n-- > 0)
 		len += scnprintf(buf + len, PAGE_SIZE - len,
 			"%d.%06d ", vals[n][0], vals[n][1]);

 	/* replace trailing space by newline */
 	buf[len - 1] = '\n';

 	return len;
 }

 static int mma8452_get_int_plus_micros_index(const int (*vals)[2], int n,
 					int val, int val2)
 {
 	while (n-- > 0)
 		if (val == vals[n][0] && val2 == vals[n][1])
 			return n;

 	return -EINVAL;
 }

 static const int mma8452_samp_freq[8][2] = {
 	{800, 0}, {400, 0}, {200, 0}, {100, 0}, {50, 0}, {12, 500000},
 	{6, 250000}, {1, 560000}
 };

 /*
  * Hardware has fullscale of -2G, -4G, -8G corresponding to raw value -2048
  * The userspace interface uses m/s^2 and we declare micro units
  * So scale factor is given by:
  * 	g * N * 1000000 / 2048 for N = 2, 4, 8 and g=9.80665
  */
 static const int mma8452_scales[3][2] = {
 	{0, 9577}, {0, 19154}, {0, 38307}
 };

 static ssize_t mma8452_show_samp_freq_avail(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	return mma8452_show_int_plus_micros(buf, mma8452_samp_freq,
 		ARRAY_SIZE(mma8452_samp_freq));
 }

 static ssize_t mma8452_show_scale_avail(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	return mma8452_show_int_plus_micros(buf, mma8452_scales,
 		ARRAY_SIZE(mma8452_scales));
 }

 static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mma8452_show_samp_freq_avail);
 static IIO_DEVICE_ATTR(in_accel_scale_available, S_IRUGO,
 	mma8452_show_scale_avail, NULL, 0);

 static int mma8452_get_samp_freq_index(struct mma8452_data *data,
 	int val, int val2)
 {
 	return mma8452_get_int_plus_micros_index(mma8452_samp_freq,
 		ARRAY_SIZE(mma8452_samp_freq), val, val2);
 }

 static int mma8452_get_scale_index(struct mma8452_data *data,
 	int val, int val2)
 {
 	return mma8452_get_int_plus_micros_index(mma8452_scales,
 		ARRAY_SIZE(mma8452_scales), val, val2);
 }

 static int mma8452_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int *val, int *val2, long mask)
 {
 	struct mma8452_data *data = iio_priv(indio_dev);
 	__be16 buffer[3];
 	int i, ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		if (iio_buffer_enabled(indio_dev))
 			return -EBUSY;

 		mutex_lock(&data->lock);
 		ret = mma8452_read(data, buffer);
 		mutex_unlock(&data->lock);
 		if (ret < 0)
 			return ret;
 		*val = sign_extend32(
 			be16_to_cpu(buffer[chan->scan_index]) >> 4, 11);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		i = data->data_cfg & MMA8452_DATA_CFG_FS_MASK;
 		*val = mma8452_scales[i][0];
 		*val2 = mma8452_scales[i][1];
 		return IIO_VAL_INT_PLUS_MICRO;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		i = (data->ctrl_reg1 & MMA8452_CTRL_DR_MASK) >>
 			MMA8452_CTRL_DR_SHIFT;
 		*val = mma8452_samp_freq[i][0];
 		*val2 = mma8452_samp_freq[i][1];
 		return IIO_VAL_INT_PLUS_MICRO;
 	case IIO_CHAN_INFO_CALIBBIAS:
 		ret = i2c_smbus_read_byte_data(data->client, MMA8452_OFF_X +
 			chan->scan_index);
 		if (ret < 0)
 			return ret;
 		*val = sign_extend32(ret, 7);
 		return IIO_VAL_INT;
 	}
 	return -EINVAL;
 }

 static int mma8452_standby(struct mma8452_data *data)
 {
 	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
 		data->ctrl_reg1 & ~MMA8452_CTRL_ACTIVE);
 }

 static int mma8452_active(struct mma8452_data *data)
 {
 	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
 		data->ctrl_reg1);
 }

 static int mma8452_change_config(struct mma8452_data *data, u8 reg, u8 val)
 {
 	int ret;

 	mutex_lock(&data->lock);

 	/* config can only be changed when in standby */
 	ret = mma8452_standby(data);
 	if (ret < 0)
 		goto fail;

 	ret = i2c_smbus_write_byte_data(data->client, reg, val);
 	if (ret < 0)
 		goto fail;

 	ret = mma8452_active(data);
 	if (ret < 0)
 		goto fail;

 	ret = 0;
 fail:
 	mutex_unlock(&data->lock);
 	return ret;
 }

 static int mma8452_write_raw(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     int val, int val2, long mask)
 {
 	struct mma8452_data *data = iio_priv(indio_dev);
 	int i;

 	if (iio_buffer_enabled(indio_dev))
 		return -EBUSY;

 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		i = mma8452_get_samp_freq_index(data, val, val2);
 		if (i < 0)
 			return -EINVAL;

 		data->ctrl_reg1 &= ~MMA8452_CTRL_DR_MASK;
 		data->ctrl_reg1 |= i << MMA8452_CTRL_DR_SHIFT;
 		return mma8452_change_config(data, MMA8452_CTRL_REG1,
 			data->ctrl_reg1);
 	case IIO_CHAN_INFO_SCALE:
 		i = mma8452_get_scale_index(data, val, val2);
 		if (i < 0)
 			return -EINVAL;
 		data->data_cfg &= ~MMA8452_DATA_CFG_FS_MASK;
 		data->data_cfg |= i;
 		return mma8452_change_config(data, MMA8452_DATA_CFG,
 			data->data_cfg);
 	case IIO_CHAN_INFO_CALIBBIAS:
 		if (val < -128 || val > 127)
 			return -EINVAL;
 		return mma8452_change_config(data, MMA8452_OFF_X +
 			chan->scan_index, val);
 	default:
 		return -EINVAL;
 	}
 }

 static irqreturn_t mma8452_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct mma8452_data *data = iio_priv(indio_dev);
 	u8 buffer[16]; /* 3 16-bit channels + padding + ts */
 	int ret;

 	ret = mma8452_read(data, (__be16 *) buffer);
 	if (ret < 0)
 		goto done;

 	iio_push_to_buffers_with_timestamp(indio_dev, buffer,
 		iio_get_time_ns());

 done:
 	iio_trigger_notify_done(indio_dev->trig);
 	return IRQ_HANDLED;
 }

 #define MMA8452_CHANNEL(axis, idx) { \
 	.type = IIO_ACCEL, \
 	.modified = 1, \
 	.channel2 = IIO_MOD_##axis, \
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
 		BIT(IIO_CHAN_INFO_CALIBBIAS), \
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
 		BIT(IIO_CHAN_INFO_SCALE), \
 	.scan_index = idx, \
 	.scan_type = { \
 		.sign = 's', \
 		.realbits = 12, \
 		.storagebits = 16, \
 		.shift = 4, \
 		.endianness = IIO_BE, \
 	}, \
 }

 static const struct iio_chan_spec mma8452_channels[] = {
 	MMA8452_CHANNEL(X, 0),
 	MMA8452_CHANNEL(Y, 1),
 	MMA8452_CHANNEL(Z, 2),
 	IIO_CHAN_SOFT_TIMESTAMP(3),
 };

 static struct attribute *mma8452_attributes[] = {
 	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
 	&iio_dev_attr_in_accel_scale_available.dev_attr.attr,
 	NULL
 };

 static const struct attribute_group mma8452_group = {
 	.attrs = mma8452_attributes,
 };

 static const struct iio_info mma8452_info = {
 	.attrs = &mma8452_group,
 	.read_raw = &mma8452_read_raw,
 	.write_raw = &mma8452_write_raw,
 	.driver_module = THIS_MODULE,
 };

 static const unsigned long mma8452_scan_masks[] = {0x7, 0};

 static int mma8452_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct mma8452_data *data;
 	struct iio_dev *indio_dev;
 	int ret;

 	ret = i2c_smbus_read_byte_data(client, MMA8452_WHO_AM_I);
 	if (ret < 0)
 		return ret;
 	if (ret != MMA8452_DEVICE_ID)
 		return -ENODEV;

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

 	data = iio_priv(indio_dev);
 	data->client = client;
 	mutex_init(&data->lock);

 	i2c_set_clientdata(client, indio_dev);
 	indio_dev->info = &mma8452_info;
 	indio_dev->name = id->name;
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = mma8452_channels;
 	indio_dev->num_channels = ARRAY_SIZE(mma8452_channels);
 	indio_dev->available_scan_masks = mma8452_scan_masks;

 	data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
 		(MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
 	ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
 		data->ctrl_reg1);
 	if (ret < 0)
 		return ret;

 	data->data_cfg = MMA8452_DATA_CFG_FS_2G;
 	ret = i2c_smbus_write_byte_data(client, MMA8452_DATA_CFG,
 		data->data_cfg);
 	if (ret < 0)
 		return ret;

 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 		mma8452_trigger_handler, NULL);
 	if (ret < 0)
 		return ret;

 	ret = iio_device_register(indio_dev);
 	if (ret < 0)
 		goto buffer_cleanup;
 	return 0;

 buffer_cleanup:
 	iio_triggered_buffer_cleanup(indio_dev);
 	return ret;
 }

 static int mma8452_remove(struct i2c_client *client)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);

 	iio_device_unregister(indio_dev);
 	iio_triggered_buffer_cleanup(indio_dev);
 	mma8452_standby(iio_priv(indio_dev));

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int mma8452_suspend(struct device *dev)
 {
 	return mma8452_standby(iio_priv(i2c_get_clientdata(
 		to_i2c_client(dev))));
 }

 static int mma8452_resume(struct device *dev)
 {
 	return mma8452_active(iio_priv(i2c_get_clientdata(
 		to_i2c_client(dev))));
 }

 static SIMPLE_DEV_PM_OPS(mma8452_pm_ops, mma8452_suspend, mma8452_resume);
 #define MMA8452_PM_OPS (&mma8452_pm_ops)
 #else
 #define MMA8452_PM_OPS NULL
 #endif

 static const struct i2c_device_id mma8452_id[] = {
 	{ "mma8452", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, mma8452_id);

 static const struct of_device_id mma8452_dt_ids[] = {
 	{ .compatible = "fsl,mma8452" },
 	{ }
 };

 static struct i2c_driver mma8452_driver = {
 	.driver = {
 		.name	= "mma8452",
 		.of_match_table = of_match_ptr(mma8452_dt_ids),
 		.pm	= MMA8452_PM_OPS,
 	},
 	.probe = mma8452_probe,
 	.remove = mma8452_remove,
 	.id_table = mma8452_id,
 };
 module_i2c_driver(mma8452_driver);

 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
 MODULE_DESCRIPTION("Freescale MMA8452 accelerometer driver");
 MODULE_LICENSE("GPL");
	/*
	* mma8452.c - Support for Freescale MMA8452Q 3-axis 12-bit accelerometer
	*
	* Copyright 2014 Peter Meerwald <pmeerw@pmeerw.net>
	*
	* This file is subject to the terms and conditions of version 2 of
	* the GNU General Public License. See the file COPYING in the main
	* directory of this archive for more details.
	*
	* 7-bit I2C slave address 0x1c/0x1d (pin selectable)
	*
	* TODO: interrupt, thresholding, orientation / freefall events, autosleep
	*/

	#include <linux/module.h>
	#include <linux/i2c.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/iio/trigger_consumer.h>
	#include <linux/iio/buffer.h>
	#include <linux/iio/triggered_buffer.h>
	#include <linux/delay.h>

	#define MMA8452_STATUS 0x00
	#define MMA8452_OUT_X 0x01 /* MSB first, 12-bit */
	#define MMA8452_OUT_Y 0x03
	#define MMA8452_OUT_Z 0x05
	#define MMA8452_WHO_AM_I 0x0d
	#define MMA8452_DATA_CFG 0x0e
	#define MMA8452_OFF_X 0x2f
	#define MMA8452_OFF_Y 0x30
	#define MMA8452_OFF_Z 0x31
	#define MMA8452_CTRL_REG1 0x2a
	#define MMA8452_CTRL_REG2 0x2b

	#define MMA8452_STATUS_DRDY (BIT(2) \| BIT(1) \| BIT(0))

	#define MMA8452_CTRL_DR_MASK (BIT(5) \| BIT(4) \| BIT(3))
	#define MMA8452_CTRL_DR_SHIFT 3
	#define MMA8452_CTRL_DR_DEFAULT 0x4 /* 50 Hz sample frequency */
	#define MMA8452_CTRL_ACTIVE BIT(0)

	#define MMA8452_DATA_CFG_FS_MASK (BIT(1) \| BIT(0))
	#define MMA8452_DATA_CFG_FS_2G 0
	#define MMA8452_DATA_CFG_FS_4G 1
	#define MMA8452_DATA_CFG_FS_8G 2

	#define MMA8452_DEVICE_ID 0x2a

	struct mma8452_data {
	struct i2c_client *client;
	struct mutex lock;
	u8 ctrl_reg1;
	u8 data_cfg;
	};

	static int mma8452_drdy(struct mma8452_data *data)
	{
	int tries = 150;

	while (tries-- > 0) {
	int ret = i2c_smbus_read_byte_data(data->client,
	MMA8452_STATUS);
	if (ret < 0)
	return ret;
	if ((ret & MMA8452_STATUS_DRDY) == MMA8452_STATUS_DRDY)
	return 0;
	msleep(20);
	}

	dev_err(&data->client->dev, "data not ready\n");
	return -EIO;
	}

	static int mma8452_read(struct mma8452_data *data, __be16 buf[3])
	{
	int ret = mma8452_drdy(data);
	if (ret < 0)
	return ret;
	return i2c_smbus_read_i2c_block_data(data->client,
	MMA8452_OUT_X, 3 * sizeof(__be16), (u8 *) buf);
	}

	static ssize_t mma8452_show_int_plus_micros(char *buf,
	const int (*vals)[2], int n)
	{
	size_t len = 0;

	while (n-- > 0)
	len += scnprintf(buf + len, PAGE_SIZE - len,
	"%d.%06d ", vals[n][0], vals[n][1]);

	/* replace trailing space by newline */
	buf[len - 1] = '\n';

	return len;
	}

	static int mma8452_get_int_plus_micros_index(const int (*vals)[2], int n,
	int val, int val2)
	{
	while (n-- > 0)
	if (val == vals[n][0] && val2 == vals[n][1])
	return n;

	return -EINVAL;
	}

	static const int mma8452_samp_freq[8][2] = {
	{800, 0}, {400, 0}, {200, 0}, {100, 0}, {50, 0}, {12, 500000},
	{6, 250000}, {1, 560000}
	};

	/*
	* Hardware has fullscale of -2G, -4G, -8G corresponding to raw value -2048
	* The userspace interface uses m/s^2 and we declare micro units
	* So scale factor is given by:
	* g * N * 1000000 / 2048 for N = 2, 4, 8 and g=9.80665
	*/
	static const int mma8452_scales[3][2] = {
	{0, 9577}, {0, 19154}, {0, 38307}
	};

	static ssize_t mma8452_show_samp_freq_avail(struct device *dev,
	struct device_attribute attr, char buf)
	{
	return mma8452_show_int_plus_micros(buf, mma8452_samp_freq,
	ARRAY_SIZE(mma8452_samp_freq));
	}

	static ssize_t mma8452_show_scale_avail(struct device *dev,
	struct device_attribute attr, char buf)
	{
	return mma8452_show_int_plus_micros(buf, mma8452_scales,
	ARRAY_SIZE(mma8452_scales));
	}

	static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mma8452_show_samp_freq_avail);
	static IIO_DEVICE_ATTR(in_accel_scale_available, S_IRUGO,
	mma8452_show_scale_avail, NULL, 0);

	static int mma8452_get_samp_freq_index(struct mma8452_data *data,
	int val, int val2)
	{
	return mma8452_get_int_plus_micros_index(mma8452_samp_freq,
	ARRAY_SIZE(mma8452_samp_freq), val, val2);
	}

	static int mma8452_get_scale_index(struct mma8452_data *data,
	int val, int val2)
	{
	return mma8452_get_int_plus_micros_index(mma8452_scales,
	ARRAY_SIZE(mma8452_scales), val, val2);
	}

	static int mma8452_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct mma8452_data *data = iio_priv(indio_dev);
	__be16 buffer[3];
	int i, ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	if (iio_buffer_enabled(indio_dev))
	return -EBUSY;

	mutex_lock(&data->lock);
	ret = mma8452_read(data, buffer);
	mutex_unlock(&data->lock);
	if (ret < 0)
	return ret;
	*val = sign_extend32(
	be16_to_cpu(buffer[chan->scan_index]) >> 4, 11);
	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	i = data->data_cfg & MMA8452_DATA_CFG_FS_MASK;
	*val = mma8452_scales[i][0];
	*val2 = mma8452_scales[i][1];
	return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_SAMP_FREQ:
	i = (data->ctrl_reg1 & MMA8452_CTRL_DR_MASK) >>
	MMA8452_CTRL_DR_SHIFT;
	*val = mma8452_samp_freq[i][0];
	*val2 = mma8452_samp_freq[i][1];
	return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_CALIBBIAS:
	ret = i2c_smbus_read_byte_data(data->client, MMA8452_OFF_X +
	chan->scan_index);
	if (ret < 0)
	return ret;
	*val = sign_extend32(ret, 7);
	return IIO_VAL_INT;
	}
	return -EINVAL;
	}

	static int mma8452_standby(struct mma8452_data *data)
	{
	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
	data->ctrl_reg1 & ~MMA8452_CTRL_ACTIVE);
	}

	static int mma8452_active(struct mma8452_data *data)
	{
	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
	data->ctrl_reg1);
	}

	static int mma8452_change_config(struct mma8452_data *data, u8 reg, u8 val)
	{
	int ret;

	mutex_lock(&data->lock);

	/* config can only be changed when in standby */
	ret = mma8452_standby(data);
	if (ret < 0)
	goto fail;

	ret = i2c_smbus_write_byte_data(data->client, reg, val);
	if (ret < 0)
	goto fail;

	ret = mma8452_active(data);
	if (ret < 0)
	goto fail;

	ret = 0;
	fail:
	mutex_unlock(&data->lock);
	return ret;
	}

	static int mma8452_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct mma8452_data *data = iio_priv(indio_dev);
	int i;

	if (iio_buffer_enabled(indio_dev))
	return -EBUSY;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
	i = mma8452_get_samp_freq_index(data, val, val2);
	if (i < 0)
	return -EINVAL;

	data->ctrl_reg1 &= ~MMA8452_CTRL_DR_MASK;
	data->ctrl_reg1 \|= i << MMA8452_CTRL_DR_SHIFT;
	return mma8452_change_config(data, MMA8452_CTRL_REG1,
	data->ctrl_reg1);
	case IIO_CHAN_INFO_SCALE:
	i = mma8452_get_scale_index(data, val, val2);
	if (i < 0)
	return -EINVAL;
	data->data_cfg &= ~MMA8452_DATA_CFG_FS_MASK;
	data->data_cfg \|= i;
	return mma8452_change_config(data, MMA8452_DATA_CFG,
	data->data_cfg);
	case IIO_CHAN_INFO_CALIBBIAS:
	if (val < -128 \|\| val > 127)
	return -EINVAL;
	return mma8452_change_config(data, MMA8452_OFF_X +
	chan->scan_index, val);
	default:
	return -EINVAL;
	}
	}

	static irqreturn_t mma8452_trigger_handler(int irq, void *p)
	{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct mma8452_data *data = iio_priv(indio_dev);
	u8 buffer[16]; /* 3 16-bit channels + padding + ts */
	int ret;

	ret = mma8452_read(data, (__be16 *) buffer);
	if (ret < 0)
	goto done;

	iio_push_to_buffers_with_timestamp(indio_dev, buffer,
	iio_get_time_ns());

	done:
	iio_trigger_notify_done(indio_dev->trig);
	return IRQ_HANDLED;
	}

	#define MMA8452_CHANNEL(axis, idx) { \
	.type = IIO_ACCEL, \
	.modified = 1, \
	.channel2 = IIO_MOD_##axis, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \| \
	BIT(IIO_CHAN_INFO_CALIBBIAS), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) \| \
	BIT(IIO_CHAN_INFO_SCALE), \
	.scan_index = idx, \
	.scan_type = { \
	.sign = 's', \
	.realbits = 12, \
	.storagebits = 16, \
	.shift = 4, \
	.endianness = IIO_BE, \
	}, \
	}

	static const struct iio_chan_spec mma8452_channels[] = {
	MMA8452_CHANNEL(X, 0),
	MMA8452_CHANNEL(Y, 1),
	MMA8452_CHANNEL(Z, 2),
	IIO_CHAN_SOFT_TIMESTAMP(3),
	};

	static struct attribute *mma8452_attributes[] = {
	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
	&iio_dev_attr_in_accel_scale_available.dev_attr.attr,
	NULL
	};

	static const struct attribute_group mma8452_group = {
	.attrs = mma8452_attributes,
	};

	static const struct iio_info mma8452_info = {
	.attrs = &mma8452_group,
	.read_raw = &mma8452_read_raw,
	.write_raw = &mma8452_write_raw,
	.driver_module = THIS_MODULE,
	};

	static const unsigned long mma8452_scan_masks[] = {0x7, 0};

	static int mma8452_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct mma8452_data *data;
	struct iio_dev *indio_dev;
	int ret;

	ret = i2c_smbus_read_byte_data(client, MMA8452_WHO_AM_I);
	if (ret < 0)
	return ret;
	if (ret != MMA8452_DEVICE_ID)
	return -ENODEV;

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

	data = iio_priv(indio_dev);
	data->client = client;
	mutex_init(&data->lock);

	i2c_set_clientdata(client, indio_dev);
	indio_dev->info = &mma8452_info;
	indio_dev->name = id->name;
	indio_dev->dev.parent = &client->dev;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = mma8452_channels;
	indio_dev->num_channels = ARRAY_SIZE(mma8452_channels);
	indio_dev->available_scan_masks = mma8452_scan_masks;

	data->ctrl_reg1 = MMA8452_CTRL_ACTIVE \|
	(MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
	ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
	data->ctrl_reg1);
	if (ret < 0)
	return ret;

	data->data_cfg = MMA8452_DATA_CFG_FS_2G;
	ret = i2c_smbus_write_byte_data(client, MMA8452_DATA_CFG,
	data->data_cfg);
	if (ret < 0)
	return ret;

	ret = iio_triggered_buffer_setup(indio_dev, NULL,
	mma8452_trigger_handler, NULL);
	if (ret < 0)
	return ret;

	ret = iio_device_register(indio_dev);
	if (ret < 0)
	goto buffer_cleanup;
	return 0;

	buffer_cleanup:
	iio_triggered_buffer_cleanup(indio_dev);
	return ret;
	}

	static int mma8452_remove(struct i2c_client *client)
	{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);

	iio_device_unregister(indio_dev);
	iio_triggered_buffer_cleanup(indio_dev);
	mma8452_standby(iio_priv(indio_dev));

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int mma8452_suspend(struct device *dev)
	{
	return mma8452_standby(iio_priv(i2c_get_clientdata(
	to_i2c_client(dev))));
	}

	static int mma8452_resume(struct device *dev)
	{
	return mma8452_active(iio_priv(i2c_get_clientdata(
	to_i2c_client(dev))));
	}

	static SIMPLE_DEV_PM_OPS(mma8452_pm_ops, mma8452_suspend, mma8452_resume);
	#define MMA8452_PM_OPS (&mma8452_pm_ops)
	#else
	#define MMA8452_PM_OPS NULL
	#endif

	static const struct i2c_device_id mma8452_id[] = {
	{ "mma8452", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, mma8452_id);

	static const struct of_device_id mma8452_dt_ids[] = {
	{ .compatible = "fsl,mma8452" },
	{ }
	};

	static struct i2c_driver mma8452_driver = {
	.driver = {
	.name = "mma8452",
	.of_match_table = of_match_ptr(mma8452_dt_ids),
	.pm = MMA8452_PM_OPS,
	},
	.probe = mma8452_probe,
	.remove = mma8452_remove,
	.id_table = mma8452_id,
	};
	module_i2c_driver(mma8452_driver);

	MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
	MODULE_DESCRIPTION("Freescale MMA8452 accelerometer driver");
	MODULE_LICENSE("GPL");