/*
 * mag3110.c - Support for Freescale MAG3110 magnetometer sensor
 *
 * Copyright (c) 2013 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 0x0e)
 *
 * TODO: irq, user offset, oversampling, continuous mode
 */

#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 MAG3110_STATUS 0x00
#define MAG3110_OUT_X 0x01 /* MSB first */
#define MAG3110_OUT_Y 0x03
#define MAG3110_OUT_Z 0x05
#define MAG3110_WHO_AM_I 0x07
#define MAG3110_SYSMOD 0x08
#define MAG3110_OFF_X 0x09 /* MSB first */
#define MAG3110_OFF_Y 0x0b
#define MAG3110_OFF_Z 0x0d
#define MAG3110_DIE_TEMP 0x0f
#define MAG3110_CTRL_REG1 0x10
#define MAG3110_CTRL_REG2 0x11

#define MAG3110_STATUS_DRDY (BIT(2) | BIT(1) | BIT(0))

#define MAG3110_CTRL_DR_MASK (BIT(7) | BIT(6) | BIT(5))
#define MAG3110_CTRL_DR_SHIFT 5
#define MAG3110_CTRL_DR_DEFAULT 0

#define MAG3110_SYSMOD_MODE_MASK GENMASK(1, 0)

#define MAG3110_CTRL_TM BIT(1) /* trigger single measurement */
#define MAG3110_CTRL_AC BIT(0) /* continuous measurements */

#define MAG3110_CTRL_AUTO_MRST_EN BIT(7) /* magnetic auto-reset */
#define MAG3110_CTRL_RAW BIT(5) /* measurements not user-offset corrected */

#define MAG3110_DEVICE_ID 0xc4

/* Each client has this additional data */
struct mag3110_data {
	struct i2c_client *client;
	struct mutex lock;
	u8 ctrl_reg1;
	int sleep_val;
	/* Ensure natural alignment of timestamp */
	struct {
		__be16 channels[3];
		u8 temperature;
		s64 ts __aligned(8);
	} scan;
};

static int mag3110_request(struct mag3110_data *data)
{
	int ret, tries = 150;

	if ((data->ctrl_reg1 & MAG3110_CTRL_AC) == 0) {
		/* trigger measurement */
		ret = i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
			data->ctrl_reg1 | MAG3110_CTRL_TM);
		if (ret < 0)
			return ret;
	}

	while (tries-- > 0) {
		ret = i2c_smbus_read_byte_data(data->client, MAG3110_STATUS);
		if (ret < 0)
			return ret;
		/* wait for data ready */
		if ((ret & MAG3110_STATUS_DRDY) == MAG3110_STATUS_DRDY)
			break;

		if (data->sleep_val <= 20)
			usleep_range(data->sleep_val * 250, data->sleep_val * 500);
		else
			msleep(20);
	}

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

	return 0;
}

static int mag3110_read(struct mag3110_data *data, __be16 buf[3])
{
	int ret;

	mutex_lock(&data->lock);
	ret = mag3110_request(data);
	if (ret < 0) {
		mutex_unlock(&data->lock);
		return ret;
	}
	ret = i2c_smbus_read_i2c_block_data(data->client,
		MAG3110_OUT_X, 3 * sizeof(__be16), (u8 *) buf);
	mutex_unlock(&data->lock);

	return ret;
}

static ssize_t mag3110_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 mag3110_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 mag3110_samp_freq[8][2] = {
	{80, 0}, {40, 0}, {20, 0}, {10, 0}, {5, 0}, {2, 500000},
	{1, 250000}, {0, 625000}
};

static ssize_t mag3110_show_samp_freq_avail(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	return mag3110_show_int_plus_micros(buf, mag3110_samp_freq, 8);
}

static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mag3110_show_samp_freq_avail);

static int mag3110_get_samp_freq_index(struct mag3110_data *data,
	int val, int val2)
{
	return mag3110_get_int_plus_micros_index(mag3110_samp_freq, 8, val,
		val2);
}

static int mag3110_calculate_sleep(struct mag3110_data *data)
{
	int ret, i = data->ctrl_reg1 >> MAG3110_CTRL_DR_SHIFT;

	if (mag3110_samp_freq[i][0] > 0)
		ret = 1000 / mag3110_samp_freq[i][0];
	else
		ret = 1000;

	return ret == 0 ? 1 : ret;
}

static int mag3110_standby(struct mag3110_data *data)
{
	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
		data->ctrl_reg1 & ~MAG3110_CTRL_AC);
}

static int mag3110_wait_standby(struct mag3110_data *data)
{
	int ret, tries = 30;

	/*
	 * Takes up to 1/ODR to come out of active mode into stby
	 * Longest expected period is 12.5seconds.
	 * We'll sleep for 500ms between checks
	 */
	while (tries-- > 0) {
		ret = i2c_smbus_read_byte_data(data->client, MAG3110_SYSMOD);
		if (ret < 0) {
			dev_err(&data->client->dev, "i2c error\n");
			return ret;
		}
		/* wait for standby */
		if ((ret & MAG3110_SYSMOD_MODE_MASK) == 0)
			break;

		msleep_interruptible(500);
	}

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

	return 0;
}

static int mag3110_active(struct mag3110_data *data)
{
	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
					 data->ctrl_reg1);
}

/* returns >0 if active, 0 if in standby and <0 on error */
static int mag3110_is_active(struct mag3110_data *data)
{
	int reg;

	reg = i2c_smbus_read_byte_data(data->client, MAG3110_CTRL_REG1);
	if (reg < 0)
		return reg;

	return reg & MAG3110_CTRL_AC;
}

static int mag3110_change_config(struct mag3110_data *data, u8 reg, u8 val)
{
	int ret;
	int is_active;

	mutex_lock(&data->lock);

	is_active = mag3110_is_active(data);
	if (is_active < 0) {
		ret = is_active;
		goto fail;
	}

	/* config can only be changed when in standby */
	if (is_active > 0) {
		ret = mag3110_standby(data);
		if (ret < 0)
			goto fail;
	}

	/*
	 * After coming out of active we must wait for the part
	 * to transition to STBY. This can take up to 1 /ODR to occur
	 */
	ret = mag3110_wait_standby(data);
	if (ret < 0)
		goto fail;

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

	if (is_active > 0) {
		ret = mag3110_active(data);
		if (ret < 0)
			goto fail;
	}

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

	return ret;
}

static int mag3110_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2, long mask)
{
	struct mag3110_data *data = iio_priv(indio_dev);
	__be16 buffer[3];
	int i, ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = iio_device_claim_direct_mode(indio_dev);
		if (ret)
			return ret;

		switch (chan->type) {
		case IIO_MAGN: /* in 0.1 uT / LSB */
			ret = mag3110_read(data, buffer);
			if (ret < 0)
				goto release;
			*val = sign_extend32(
				be16_to_cpu(buffer[chan->scan_index]), 15);
			ret = IIO_VAL_INT;
			break;
		case IIO_TEMP: /* in 1 C / LSB */
			mutex_lock(&data->lock);
			ret = mag3110_request(data);
			if (ret < 0) {
				mutex_unlock(&data->lock);
				goto release;
			}
			ret = i2c_smbus_read_byte_data(data->client,
				MAG3110_DIE_TEMP);
			mutex_unlock(&data->lock);
			if (ret < 0)
				goto release;
			*val = sign_extend32(ret, 7);
			ret = IIO_VAL_INT;
			break;
		default:
			ret = -EINVAL;
		}
release:
		iio_device_release_direct_mode(indio_dev);
		return ret;

	case IIO_CHAN_INFO_SCALE:
		switch (chan->type) {
		case IIO_MAGN:
			*val = 0;
			*val2 = 1000;
			return IIO_VAL_INT_PLUS_MICRO;
		case IIO_TEMP:
			*val = 1000;
			return IIO_VAL_INT;
		default:
			return -EINVAL;
		}
	case IIO_CHAN_INFO_SAMP_FREQ:
		i = data->ctrl_reg1 >> MAG3110_CTRL_DR_SHIFT;
		*val = mag3110_samp_freq[i][0];
		*val2 = mag3110_samp_freq[i][1];
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_CALIBBIAS:
		ret = i2c_smbus_read_word_swapped(data->client,
			MAG3110_OFF_X +	2 * chan->scan_index);
		if (ret < 0)
			return ret;
		*val = sign_extend32(ret >> 1, 14);
		return IIO_VAL_INT;
	}
	return -EINVAL;
}

static int mag3110_write_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int val, int val2, long mask)
{
	struct mag3110_data *data = iio_priv(indio_dev);
	int rate, ret;

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

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
		rate = mag3110_get_samp_freq_index(data, val, val2);
		if (rate < 0) {
			ret = -EINVAL;
			break;
		}
		data->ctrl_reg1 &= 0xff & ~MAG3110_CTRL_DR_MASK
					& ~MAG3110_CTRL_AC;
		data->ctrl_reg1 |= rate << MAG3110_CTRL_DR_SHIFT;
		data->sleep_val = mag3110_calculate_sleep(data);
		if (data->sleep_val < 40)
			data->ctrl_reg1 |= MAG3110_CTRL_AC;

		ret = mag3110_change_config(data, MAG3110_CTRL_REG1,
					    data->ctrl_reg1);
		break;
	case IIO_CHAN_INFO_CALIBBIAS:
		if (val < -10000 || val > 10000) {
			ret = -EINVAL;
			break;
		}
		ret = i2c_smbus_write_word_swapped(data->client,
			MAG3110_OFF_X + 2 * chan->scan_index, val << 1);
		break;
	default:
		ret = -EINVAL;
		break;
	}
	iio_device_release_direct_mode(indio_dev);
	return ret;
}

static irqreturn_t mag3110_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct mag3110_data *data = iio_priv(indio_dev);
	int ret;

	ret = mag3110_read(data, data->scan.channels);
	if (ret < 0)
		goto done;

	if (test_bit(3, indio_dev->active_scan_mask)) {
		ret = i2c_smbus_read_byte_data(data->client,
			MAG3110_DIE_TEMP);
		if (ret < 0)
			goto done;
		data->scan.temperature = ret;
	}

	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
		iio_get_time_ns(indio_dev));

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

#define MAG3110_CHANNEL(axis, idx) { \
	.type = IIO_MAGN, \
	.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 = 16, \
		.storagebits = 16, \
		.endianness = IIO_BE, \
	}, \
}

static const struct iio_chan_spec mag3110_channels[] = {
	MAG3110_CHANNEL(X, 0),
	MAG3110_CHANNEL(Y, 1),
	MAG3110_CHANNEL(Z, 2),
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
			BIT(IIO_CHAN_INFO_SCALE),
		.scan_index = 3,
		.scan_type = {
			.sign = 's',
			.realbits = 8,
			.storagebits = 8,
			},
	},
	IIO_CHAN_SOFT_TIMESTAMP(4),
};

static struct attribute *mag3110_attributes[] = {
	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
	NULL
};

static const struct attribute_group mag3110_group = {
	.attrs = mag3110_attributes,
};

static const struct iio_info mag3110_info = {
	.attrs = &mag3110_group,
	.read_raw = &mag3110_read_raw,
	.write_raw = &mag3110_write_raw,
};

static const unsigned long mag3110_scan_masks[] = {0x7, 0xf, 0};

static int mag3110_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct mag3110_data *data;
	struct iio_dev *indio_dev;
	int ret;

	ret = i2c_smbus_read_byte_data(client, MAG3110_WHO_AM_I);
	if (ret < 0)
		return ret;
	if (ret != MAG3110_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 = &mag3110_info;
	indio_dev->name = id->name;
	indio_dev->dev.parent = &client->dev;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = mag3110_channels;
	indio_dev->num_channels = ARRAY_SIZE(mag3110_channels);
	indio_dev->available_scan_masks = mag3110_scan_masks;

	data->ctrl_reg1 = MAG3110_CTRL_DR_DEFAULT << MAG3110_CTRL_DR_SHIFT;
	data->sleep_val = mag3110_calculate_sleep(data);
	if (data->sleep_val < 40)
		data->ctrl_reg1 |= MAG3110_CTRL_AC;

	ret = mag3110_change_config(data, MAG3110_CTRL_REG1, data->ctrl_reg1);
	if (ret < 0)
		return ret;

	ret = i2c_smbus_write_byte_data(client, MAG3110_CTRL_REG2,
		MAG3110_CTRL_AUTO_MRST_EN);
	if (ret < 0)
		goto standby_on_error;

	ret = iio_triggered_buffer_setup(indio_dev, NULL,
		mag3110_trigger_handler, NULL);
	if (ret < 0)
		goto standby_on_error;

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

buffer_cleanup:
	iio_triggered_buffer_cleanup(indio_dev);
standby_on_error:
	mag3110_standby(iio_priv(indio_dev));
	return ret;
}

static int mag3110_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);
	mag3110_standby(iio_priv(indio_dev));

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int mag3110_suspend(struct device *dev)
{
	return mag3110_standby(iio_priv(i2c_get_clientdata(
		to_i2c_client(dev))));
}

static int mag3110_resume(struct device *dev)
{
	struct mag3110_data *data = iio_priv(i2c_get_clientdata(
		to_i2c_client(dev)));

	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
		data->ctrl_reg1);
}

static SIMPLE_DEV_PM_OPS(mag3110_pm_ops, mag3110_suspend, mag3110_resume);
#define MAG3110_PM_OPS (&mag3110_pm_ops)
#else
#define MAG3110_PM_OPS NULL
#endif

static const struct i2c_device_id mag3110_id[] = {
	{ "mag3110", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, mag3110_id);

static const struct of_device_id mag3110_of_match[] = {
	{ .compatible = "fsl,mag3110" },
	{ }
};
MODULE_DEVICE_TABLE(of, mag3110_of_match);

static struct i2c_driver mag3110_driver = {
	.driver = {
		.name	= "mag3110",
		.of_match_table = mag3110_of_match,
		.pm	= MAG3110_PM_OPS,
	},
	.probe = mag3110_probe,
	.remove = mag3110_remove,
	.id_table = mag3110_id,
};
module_i2c_driver(mag3110_driver);

MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
MODULE_DESCRIPTION("Freescale MAG3110 magnetometer driver");
MODULE_LICENSE("GPL");