/*
   * mcp4725.c - Support for Microchip MCP4725
   *
   * Copyright (C) 2012 Peter Meerwald <pmeerw@pmeerw.net>
   *
   * Based on max517 by Roland Stigge <stigge@antcom.de>
   *
   * 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.
   *
   * driver for the Microchip I2C 12-bit digital-to-analog converter (DAC)
   * (7-bit I2C slave address 0x60, the three LSBs can be configured in
   * hardware)
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/i2c.h>
  #include <linux/err.h>
  #include <linux/delay.h>
  
  #include <linux/iio/iio.h>
  #include <linux/iio/sysfs.h>
  
  #include <linux/iio/dac/mcp4725.h>
  
  #define MCP4725_DRV_NAME "mcp4725"
  
  struct mcp4725_data {
  	struct i2c_client *client;
  	u16 vref_mv;
  	u16 dac_value;
  	bool powerdown;
  	unsigned powerdown_mode;
  };
  
  static int mcp4725_suspend(struct device *dev)
  {
  	struct mcp4725_data *data = iio_priv(i2c_get_clientdata(
  		to_i2c_client(dev)));
  	u8 outbuf[2];
  
  	outbuf[0] = (data->powerdown_mode + 1) << 4;
  	outbuf[1] = 0;
  	data->powerdown = true;
  
  	return i2c_master_send(data->client, outbuf, 2);
  }
  
  static int mcp4725_resume(struct device *dev)
  {
  	struct mcp4725_data *data = iio_priv(i2c_get_clientdata(
  		to_i2c_client(dev)));
  	u8 outbuf[2];
  
  	/* restore previous DAC value */
  	outbuf[0] = (data->dac_value >> 8) & 0xf;
  	outbuf[1] = data->dac_value & 0xff;
  	data->powerdown = false;
  
  	return i2c_master_send(data->client, outbuf, 2);
  }
  
  #ifdef CONFIG_PM_SLEEP
  static SIMPLE_DEV_PM_OPS(mcp4725_pm_ops, mcp4725_suspend, mcp4725_resume);
  #define MCP4725_PM_OPS (&mcp4725_pm_ops)
  #else
  #define MCP4725_PM_OPS NULL
  #endif
  
  static ssize_t mcp4725_store_eeprom(struct device *dev,
  	struct device_attribute *attr, const char *buf, size_t len)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct mcp4725_data *data = iio_priv(indio_dev);
  	int tries = 20;
  	u8 inoutbuf[3];
  	bool state;
  	int ret;
  
  	ret = strtobool(buf, &state);
  	if (ret < 0)
  		return ret;
  
  	if (!state)
  		return 0;
  
  	inoutbuf[0] = 0x60; /* write EEPROM */
  	inoutbuf[1] = data->dac_value >> 4;
  	inoutbuf[2] = (data->dac_value & 0xf) << 4;
  
  	ret = i2c_master_send(data->client, inoutbuf, 3);
  	if (ret < 0)
  		return ret;
  	else if (ret != 3)
  		return -EIO;
  
  	/* wait for write complete, takes up to 50ms */
  	while (tries--) {
  		msleep(20);
  		ret = i2c_master_recv(data->client, inoutbuf, 3);
  		if (ret < 0)
  			return ret;
  		else if (ret != 3)
  			return -EIO;
  
  		if (inoutbuf[0] & 0x80)
  			break;
  	}
  
  	if (tries < 0) {
  		dev_err(&data->client->dev,
  			"mcp4725_store_eeprom() failed, incomplete
  ");
  		return -EIO;
  	}
  
  	return len;
  }
  
  static IIO_DEVICE_ATTR(store_eeprom, S_IWUSR, NULL, mcp4725_store_eeprom, 0);
  
  static struct attribute *mcp4725_attributes[] = {
  	&iio_dev_attr_store_eeprom.dev_attr.attr,
  	NULL,
  };
  
  static const struct attribute_group mcp4725_attribute_group = {
  	.attrs = mcp4725_attributes,
  };
  
  static const char * const mcp4725_powerdown_modes[] = {
  	"1kohm_to_gnd",
  	"100kohm_to_gnd",
  	"500kohm_to_gnd"
  };
  
  static int mcp4725_get_powerdown_mode(struct iio_dev *indio_dev,
  	const struct iio_chan_spec *chan)
  {
  	struct mcp4725_data *data = iio_priv(indio_dev);
  
  	return data->powerdown_mode;
  }
  
  static int mcp4725_set_powerdown_mode(struct iio_dev *indio_dev,
  	const struct iio_chan_spec *chan, unsigned mode)
  {
  	struct mcp4725_data *data = iio_priv(indio_dev);
  
  	data->powerdown_mode = mode;
  
  	return 0;
  }
  
  static ssize_t mcp4725_read_powerdown(struct iio_dev *indio_dev,
  	uintptr_t private, const struct iio_chan_spec *chan, char *buf)
  {
  	struct mcp4725_data *data = iio_priv(indio_dev);
  
  	return sprintf(buf, "%d
  ", data->powerdown);
  }
  
  static ssize_t mcp4725_write_powerdown(struct iio_dev *indio_dev,
  	 uintptr_t private, const struct iio_chan_spec *chan,
  	 const char *buf, size_t len)
  {
  	struct mcp4725_data *data = iio_priv(indio_dev);
  	bool state;
  	int ret;
  
  	ret = strtobool(buf, &state);
  	if (ret)
  		return ret;
  
  	if (state)
  		ret = mcp4725_suspend(&data->client->dev);
  	else
  		ret = mcp4725_resume(&data->client->dev);
  	if (ret < 0)
  		return ret;
  
  	return len;
  }
  
  static const struct iio_enum mcp4725_powerdown_mode_enum = {
  	.items = mcp4725_powerdown_modes,
  	.num_items = ARRAY_SIZE(mcp4725_powerdown_modes),
  	.get = mcp4725_get_powerdown_mode,
  	.set = mcp4725_set_powerdown_mode,
  };
  
  static const struct iio_chan_spec_ext_info mcp4725_ext_info[] = {
  	{
  		.name = "powerdown",
  		.read = mcp4725_read_powerdown,
  		.write = mcp4725_write_powerdown,
  		.shared = IIO_SEPARATE,
  	},
  	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &mcp4725_powerdown_mode_enum),
  	IIO_ENUM_AVAILABLE("powerdown_mode", &mcp4725_powerdown_mode_enum),
  	{ },
  };
  
  static const struct iio_chan_spec mcp4725_channel = {
  	.type		= IIO_VOLTAGE,
  	.indexed	= 1,
  	.output		= 1,
  	.channel	= 0,
  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
  	.ext_info	= mcp4725_ext_info,
  };
  
  static int mcp4725_set_value(struct iio_dev *indio_dev, int val)
  {
  	struct mcp4725_data *data = iio_priv(indio_dev);
  	u8 outbuf[2];
  	int ret;
  
  	if (val >= (1 << 12) || val < 0)
  		return -EINVAL;
  
  	outbuf[0] = (val >> 8) & 0xf;
  	outbuf[1] = val & 0xff;
  
  	ret = i2c_master_send(data->client, outbuf, 2);
  	if (ret < 0)
  		return ret;
  	else if (ret != 2)
  		return -EIO;
  	else
  		return 0;
  }
  
  static int mcp4725_read_raw(struct iio_dev *indio_dev,
  			   struct iio_chan_spec const *chan,
  			   int *val, int *val2, long mask)
  {
  	struct mcp4725_data *data = iio_priv(indio_dev);
  
  	switch (mask) {
  	case IIO_CHAN_INFO_RAW:
  		*val = data->dac_value;
  		return IIO_VAL_INT;
  	case IIO_CHAN_INFO_SCALE:
  		*val = data->vref_mv;
  		*val2 = 12;
  		return IIO_VAL_FRACTIONAL_LOG2;
  	}
  	return -EINVAL;
  }
  
  static int mcp4725_write_raw(struct iio_dev *indio_dev,
  			       struct iio_chan_spec const *chan,
  			       int val, int val2, long mask)
  {
  	struct mcp4725_data *data = iio_priv(indio_dev);
  	int ret;
  
  	switch (mask) {
  	case IIO_CHAN_INFO_RAW:
  		ret = mcp4725_set_value(indio_dev, val);
  		data->dac_value = val;
  		break;
  	default:
  		ret = -EINVAL;
  		break;
  	}
  
  	return ret;
  }
  
  static const struct iio_info mcp4725_info = {
  	.read_raw = mcp4725_read_raw,
  	.write_raw = mcp4725_write_raw,
  	.attrs = &mcp4725_attribute_group,
  	.driver_module = THIS_MODULE,
  };
  
  static int mcp4725_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)
  {
  	struct mcp4725_data *data;
  	struct iio_dev *indio_dev;
  	struct mcp4725_platform_data *platform_data = client->dev.platform_data;
  	u8 inbuf[3];
  	u8 pd;
  	int err;
  
  	if (!platform_data || !platform_data->vref_mv) {
  		dev_err(&client->dev, "invalid platform data");
  		return -EINVAL;
  	}
  
  	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
  	if (indio_dev == NULL)
  		return -ENOMEM;
  	data = iio_priv(indio_dev);
  	i2c_set_clientdata(client, indio_dev);
  	data->client = client;
  
  	indio_dev->dev.parent = &client->dev;
  	indio_dev->info = &mcp4725_info;
  	indio_dev->channels = &mcp4725_channel;
  	indio_dev->num_channels = 1;
  	indio_dev->modes = INDIO_DIRECT_MODE;
  
  	data->vref_mv = platform_data->vref_mv;
  
  	/* read current DAC value */
  	err = i2c_master_recv(client, inbuf, 3);
  	if (err < 0) {
  		dev_err(&client->dev, "failed to read DAC value");
  		return err;
  	}
  	pd = (inbuf[0] >> 1) & 0x3;
  	data->powerdown = pd > 0 ? true : false;
  	data->powerdown_mode = pd ? pd-1 : 2; /* 500kohm_to_gnd */
  	data->dac_value = (inbuf[1] << 4) | (inbuf[2] >> 4);
  
  	return iio_device_register(indio_dev);
  }
  
  static int mcp4725_remove(struct i2c_client *client)
  {
  	iio_device_unregister(i2c_get_clientdata(client));
  	return 0;
  }
  
  static const struct i2c_device_id mcp4725_id[] = {
  	{ "mcp4725", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, mcp4725_id);
  
  static struct i2c_driver mcp4725_driver = {
  	.driver = {
  		.name	= MCP4725_DRV_NAME,
  		.pm	= MCP4725_PM_OPS,
  	},
  	.probe		= mcp4725_probe,
  	.remove		= mcp4725_remove,
  	.id_table	= mcp4725_id,
  };
  module_i2c_driver(mcp4725_driver);
  
  MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
  MODULE_DESCRIPTION("MCP4725 12-bit DAC");
  MODULE_LICENSE("GPL");