/*
   * 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_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_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;
  };
  
  static int mag3110_request(struct mag3110_data *data)
  {
  	int ret, tries = 150;
  
  	/* 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;
  		msleep(20);
  	}
  
  	if (tries < 0) {
  		dev_err(&data->client->dev, "data not ready
  ");
  		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] = '
  ';
  
  	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_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:
  		if (iio_buffer_enabled(indio_dev))
  			return -EBUSY;
  
  		switch (chan->type) {
  		case IIO_MAGN: /* in 0.1 uT / LSB */
  			ret = mag3110_read(data, buffer);
  			if (ret < 0)
  				return ret;
  			*val = sign_extend32(
  				be16_to_cpu(buffer[chan->scan_index]), 15);
  			return IIO_VAL_INT;
  		case IIO_TEMP: /* in 1 C / LSB */
  			mutex_lock(&data->lock);
  			ret = mag3110_request(data);
  			if (ret < 0) {
  				mutex_unlock(&data->lock);
  				return ret;
  			}
  			ret = i2c_smbus_read_byte_data(data->client,
  				MAG3110_DIE_TEMP);
  			mutex_unlock(&data->lock);
  			if (ret < 0)
  				return ret;
  			*val = sign_extend32(ret, 7);
  			return IIO_VAL_INT;
  		default:
  			return -EINVAL;
  		}
  	case IIO_CHAN_INFO_SCALE:
  		*val = 0;
  		*val2 = 1000;
  		return IIO_VAL_INT_PLUS_MICRO;
  	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;
  	}
  	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;
  
  	if (iio_buffer_enabled(indio_dev))
  		return -EBUSY;
  
  	switch (mask) {
  	case IIO_CHAN_INFO_SAMP_FREQ:
  		rate = mag3110_get_samp_freq_index(data, val, val2);
  		if (rate < 0)
  			return -EINVAL;
  
  		data->ctrl_reg1 &= ~MAG3110_CTRL_DR_MASK;
  		data->ctrl_reg1 |= rate << MAG3110_CTRL_DR_SHIFT;
  		return i2c_smbus_write_byte_data(data->client,
  			MAG3110_CTRL_REG1, data->ctrl_reg1);
  	default:
  		return -EINVAL;
  	}
  }
  
  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);
  	u8 buffer[16]; /* 3 16-bit channels + 1 byte temp + padding + ts */
  	int ret;
  
  	ret = mag3110_read(data, (__be16 *) buffer);
  	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;
  		buffer[6] = ret;
  	}
  
  	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 MAG3110_CHANNEL(axis, idx) { \
  	.type = IIO_MAGN, \
  	.modified = 1, \
  	.channel2 = IIO_MOD_##axis, \
  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
  	.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),
  		.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,
  	.driver_module = THIS_MODULE,
  };
  
  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;
  	ret = i2c_smbus_write_byte_data(client, 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 | MAG3110_CTRL_RAW);
  	if (ret < 0)
  		return ret;
  
  	ret = iio_triggered_buffer_setup(indio_dev, NULL,
  		mag3110_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 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_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 struct i2c_driver mag3110_driver = {
  	.driver = {
  		.name	= "mag3110",
  		.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");