alistair23-linux/drivers/iio/magnetometer/mmc35240.c

/*
 * MMC35240 - MEMSIC 3-axis Magnetic Sensor
 *
 * Copyright (c) 2015, Intel Corporation.
 *
 * 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.
 *
 * IIO driver for MMC35240 (7-bit I2C slave address 0x30).
 *
 * TODO: offset, ACPI, continuous measurement mode, PM
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/regmap.h>
#include <linux/acpi.h>
#include <linux/pm.h>

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

#define MMC35240_DRV_NAME "mmc35240"
#define MMC35240_REGMAP_NAME "mmc35240_regmap"

#define MMC35240_REG_XOUT_L	0x00
#define MMC35240_REG_XOUT_H	0x01
#define MMC35240_REG_YOUT_L	0x02
#define MMC35240_REG_YOUT_H	0x03
#define MMC35240_REG_ZOUT_L	0x04
#define MMC35240_REG_ZOUT_H	0x05

#define MMC35240_REG_STATUS	0x06
#define MMC35240_REG_CTRL0	0x07
#define MMC35240_REG_CTRL1	0x08

#define MMC35240_REG_ID		0x20

#define MMC35240_STATUS_MEAS_DONE_BIT	BIT(0)

#define MMC35240_CTRL0_REFILL_BIT	BIT(7)
#define MMC35240_CTRL0_RESET_BIT	BIT(6)
#define MMC35240_CTRL0_SET_BIT		BIT(5)
#define MMC35240_CTRL0_CMM_BIT		BIT(1)
#define MMC35240_CTRL0_TM_BIT		BIT(0)

/* output resolution bits */
#define MMC35240_CTRL1_BW0_BIT		BIT(0)
#define MMC35240_CTRL1_BW1_BIT		BIT(1)

#define MMC35240_CTRL1_BW_MASK	 (MMC35240_CTRL1_BW0_BIT | \
		 MMC35240_CTRL1_BW1_BIT)
#define MMC35240_CTRL1_BW_SHIFT		0

#define MMC35240_WAIT_CHARGE_PUMP	50000	/* us */
#define MMC53240_WAIT_SET_RESET		1000	/* us */

enum mmc35240_resolution {
	MMC35240_16_BITS_SLOW = 0, /* 100 Hz */
	MMC35240_16_BITS_FAST,     /* 200 Hz */
	MMC35240_14_BITS,          /* 333 Hz */
	MMC35240_12_BITS,          /* 666 Hz */
};

enum mmc35240_axis {
	AXIS_X = 0,
	AXIS_Y,
	AXIS_Z,
};

static const struct {
	int sens[3]; /* sensitivity per X, Y, Z axis */
	int nfo; /* null field output */
} mmc35240_props_table[] = {
	/* 16 bits, 100Hz ODR */
	{
		{1024, 1024, 770},
		32768,
	},
	/* 16 bits, 200Hz ODR */
	{
		{1024, 1024, 770},
		32768,
	},
	/* 14 bits, 333Hz ODR */
	{
		{256, 256, 193},
		8192,
	},
	/* 12 bits, 666Hz ODR */
	{
		{64, 64, 48},
		2048,
	},
};

struct mmc35240_data {
	struct i2c_client *client;
	struct mutex mutex;
	struct regmap *regmap;
	enum mmc35240_resolution res;
};

static const int mmc35240_samp_freq[] = {100, 200, 333, 666};

static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("100 200 333 666");

#define MMC35240_CHANNEL(_axis) { \
	.type = IIO_MAGN, \
	.modified = 1, \
	.channel2 = IIO_MOD_ ## _axis, \
	.address = AXIS_ ## _axis, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
}

static const struct iio_chan_spec mmc35240_channels[] = {
	MMC35240_CHANNEL(X),
	MMC35240_CHANNEL(Y),
	MMC35240_CHANNEL(Z),
};

static struct attribute *mmc35240_attributes[] = {
	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
};

static const struct attribute_group mmc35240_attribute_group = {
	.attrs = mmc35240_attributes,
};

static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
					int val, int val2)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
		if (mmc35240_samp_freq[i] == val)
			return i;
	return -EINVAL;
}

static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
{
	int ret;
	u8 coil_bit;

	/*
	 * Recharge the capacitor at VCAP pin, requested to be issued
	 * before a SET/RESET command.
	 */
	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
				 MMC35240_CTRL0_REFILL_BIT,
				 MMC35240_CTRL0_REFILL_BIT);
	if (ret < 0)
		return ret;
	usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);

	if (set)
		coil_bit = MMC35240_CTRL0_SET_BIT;
	else
		coil_bit = MMC35240_CTRL0_RESET_BIT;

	return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
				  MMC35240_CTRL0_REFILL_BIT,
				  coil_bit);
}

static int mmc35240_init(struct mmc35240_data *data)
{
	int ret;
	unsigned int reg_id;

	ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
	if (ret < 0) {
		dev_err(&data->client->dev, "Error reading product id\n");
		return ret;
	}

	dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);

	/*
	 * make sure we restore sensor characteristics, by doing
	 * a RESET/SET sequence
	 */
	ret = mmc35240_hw_set(data, false);
	if (ret < 0)
		return ret;
	usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1);

	ret = mmc35240_hw_set(data, true);
	if (ret < 0)
		return ret;

	/* set default sampling frequency */
	return regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
				  MMC35240_CTRL1_BW_MASK,
				  data->res << MMC35240_CTRL1_BW_SHIFT);
}

static int mmc35240_take_measurement(struct mmc35240_data *data)
{
	int ret, tries = 100;
	unsigned int reg_status;

	ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
			   MMC35240_CTRL0_TM_BIT);
	if (ret < 0)
		return ret;

	while (tries-- > 0) {
		ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
				  &reg_status);
		if (ret < 0)
			return ret;
		if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
			break;
		msleep(20);
	}

	if (tries < 0) {
		dev_err(&data->client->dev, "data not ready\n");
		return -EIO;
	}

	return 0;
}

static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
{
	int ret;

	ret = mmc35240_take_measurement(data);
	if (ret < 0)
		return ret;

	return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf,
				3 * sizeof(__le16));
}

static int mmc35240_raw_to_gauss(struct mmc35240_data *data, int index,
				 __le16 buf[],
				 int *val, int *val2)
{
	int raw_x, raw_y, raw_z;
	int sens_x, sens_y, sens_z;
	int nfo;

	raw_x = le16_to_cpu(buf[AXIS_X]);
	raw_y = le16_to_cpu(buf[AXIS_Y]);
	raw_z = le16_to_cpu(buf[AXIS_Z]);

	sens_x = mmc35240_props_table[data->res].sens[AXIS_X];
	sens_y = mmc35240_props_table[data->res].sens[AXIS_Y];
	sens_z = mmc35240_props_table[data->res].sens[AXIS_Z];

	nfo = mmc35240_props_table[data->res].nfo;

	switch (index) {
	case AXIS_X:
		*val = (raw_x - nfo) / sens_x;
		*val2 = ((raw_x - nfo) % sens_x) * 1000000;
		break;
	case AXIS_Y:
		*val = (raw_y - nfo) / sens_y - (raw_z - nfo) / sens_z;
		*val2 = (((raw_y - nfo) % sens_y - (raw_z - nfo) % sens_z))
			* 1000000;
		break;
	case AXIS_Z:
		*val = (raw_y - nfo) / sens_y + (raw_z - nfo) / sens_z;
		*val2 = (((raw_y - nfo) % sens_y + (raw_z - nfo) % sens_z))
			* 1000000;
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

static int mmc35240_read_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan, int *val,
			     int *val2, long mask)
{
	struct mmc35240_data *data = iio_priv(indio_dev);
	int ret, i;
	unsigned int reg;
	__le16 buf[3];

	switch (mask) {
	case IIO_CHAN_INFO_PROCESSED:
		mutex_lock(&data->mutex);
		ret = mmc35240_read_measurement(data, buf);
		mutex_unlock(&data->mutex);
		if (ret < 0)
			return ret;
		ret = mmc35240_raw_to_gauss(data, chan->address,
					    buf, val, val2);
		if (ret < 0)
			return ret;
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_SAMP_FREQ:
		mutex_lock(&data->mutex);
		ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
		mutex_unlock(&data->mutex);
		if (ret < 0)
			return ret;

		i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
		if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
			return -EINVAL;

		*val = mmc35240_samp_freq[i];
		*val2 = 0;
		return IIO_VAL_INT;
	default:
		return -EINVAL;
	}
}

static int mmc35240_write_raw(struct iio_dev *indio_dev,
			      struct iio_chan_spec const *chan, int val,
			      int val2, long mask)
{
	struct mmc35240_data *data = iio_priv(indio_dev);
	int i, ret;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
		i = mmc35240_get_samp_freq_index(data, val, val2);
		if (i < 0)
			return -EINVAL;
		mutex_lock(&data->mutex);
		ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
					 MMC35240_CTRL1_BW_MASK,
					 i << MMC35240_CTRL1_BW_SHIFT);
		mutex_unlock(&data->mutex);
		return ret;
	default:
		return -EINVAL;
	}
}

static const struct iio_info mmc35240_info = {
	.driver_module	= THIS_MODULE,
	.read_raw	= mmc35240_read_raw,
	.write_raw	= mmc35240_write_raw,
	.attrs		= &mmc35240_attribute_group,
};

static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MMC35240_REG_CTRL0:
	case MMC35240_REG_CTRL1:
		return true;
	default:
		return false;
	}
}

static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MMC35240_REG_XOUT_L:
	case MMC35240_REG_XOUT_H:
	case MMC35240_REG_YOUT_L:
	case MMC35240_REG_YOUT_H:
	case MMC35240_REG_ZOUT_L:
	case MMC35240_REG_ZOUT_H:
	case MMC35240_REG_STATUS:
	case MMC35240_REG_ID:
		return true;
	default:
		return false;
	}
}

static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MMC35240_REG_CTRL0:
	case MMC35240_REG_CTRL1:
		return false;
	default:
		return true;
	}
}

static struct reg_default mmc35240_reg_defaults[] = {
	{ MMC35240_REG_CTRL0,  0x00 },
	{ MMC35240_REG_CTRL1,  0x00 },
};

static const struct regmap_config mmc35240_regmap_config = {
	.name = MMC35240_REGMAP_NAME,

	.reg_bits = 8,
	.val_bits = 8,

	.max_register = MMC35240_REG_ID,
	.cache_type = REGCACHE_FLAT,

	.writeable_reg = mmc35240_is_writeable_reg,
	.readable_reg = mmc35240_is_readable_reg,
	.volatile_reg = mmc35240_is_volatile_reg,

	.reg_defaults = mmc35240_reg_defaults,
	.num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
};

static int mmc35240_probe(struct i2c_client *client,
			  const struct i2c_device_id *id)
{
	struct mmc35240_data *data;
	struct iio_dev *indio_dev;
	struct regmap *regmap;
	int ret;

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

	regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
	if (IS_ERR(regmap)) {
		dev_err(&client->dev, "regmap initialization failed\n");
		return PTR_ERR(regmap);
	}

	data = iio_priv(indio_dev);
	data->client = client;
	data->regmap = regmap;
	data->res = MMC35240_16_BITS_SLOW;

	mutex_init(&data->mutex);

	indio_dev->dev.parent = &client->dev;
	indio_dev->info = &mmc35240_info;
	indio_dev->name = MMC35240_DRV_NAME;
	indio_dev->channels = mmc35240_channels;
	indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
	indio_dev->modes = INDIO_DIRECT_MODE;

	ret = mmc35240_init(data);
	if (ret < 0) {
		dev_err(&client->dev, "mmc35240 chip init failed\n");
		return ret;
	}
	return devm_iio_device_register(&client->dev, indio_dev);
}

#ifdef CONFIG_PM_SLEEP
static int mmc35240_suspend(struct device *dev)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
	struct mmc35240_data *data = iio_priv(indio_dev);

	regcache_cache_only(data->regmap, true);

	return 0;
}

static int mmc35240_resume(struct device *dev)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
	struct mmc35240_data *data = iio_priv(indio_dev);
	int ret;

	regcache_mark_dirty(data->regmap);
	ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
				   MMC35240_REG_CTRL1);
	if (ret < 0)
		dev_err(dev, "Failed to restore control registers\n");

	regcache_cache_only(data->regmap, false);

	return 0;
}
#endif

static const struct dev_pm_ops mmc35240_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume)
};

static const struct acpi_device_id mmc35240_acpi_match[] = {
	{"MMC35240", 0},
	{ },
};
MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);

static const struct i2c_device_id mmc35240_id[] = {
	{"MMC35240", 0},
	{}
};
MODULE_DEVICE_TABLE(i2c, mmc35240_id);

static struct i2c_driver mmc35240_driver = {
	.driver = {
		.name = MMC35240_DRV_NAME,
		.pm = &mmc35240_pm_ops,
		.acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
	},
	.probe		= mmc35240_probe,
	.id_table	= mmc35240_id,
};

module_i2c_driver(mmc35240_driver);

MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
MODULE_LICENSE("GPL v2");