/*
    * iio/dac/max5821.c
    * Copyright (C) 2014 Philippe Reynes
    *
    * This program is free software; you can redistribute it and/or modify
    * it under the terms of the GNU General Public License version 2 as
    * published by the Free Software Foundation.
    */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/i2c.h>
  #include <linux/iio/iio.h>
  #include <linux/regulator/consumer.h>
  
  #define MAX5821_MAX_DAC_CHANNELS		2
  
  /* command bytes */
  #define MAX5821_LOAD_DAC_A_IN_REG_B		0x00
  #define MAX5821_LOAD_DAC_B_IN_REG_A		0x10
  #define MAX5821_EXTENDED_COMMAND_MODE		0xf0
  #define MAX5821_READ_DAC_A_COMMAND		0xf1
  #define MAX5821_READ_DAC_B_COMMAND		0xf2
  
  #define MAX5821_EXTENDED_POWER_UP		0x00
  #define MAX5821_EXTENDED_POWER_DOWN_MODE0	0x01
  #define MAX5821_EXTENDED_POWER_DOWN_MODE1	0x02
  #define MAX5821_EXTENDED_POWER_DOWN_MODE2	0x03
  #define MAX5821_EXTENDED_DAC_A			0x04
  #define MAX5821_EXTENDED_DAC_B			0x08
  
  enum max5821_device_ids {
  	ID_MAX5821,
  };
  
  struct max5821_data {
  	struct i2c_client	*client;
  	struct regulator	*vref_reg;
  	unsigned short		vref_mv;
  	bool			powerdown[MAX5821_MAX_DAC_CHANNELS];
  	u8			powerdown_mode[MAX5821_MAX_DAC_CHANNELS];
  	struct mutex		lock;
  };
  
  static const char * const max5821_powerdown_modes[] = {
  	"three_state",
  	"1kohm_to_gnd",
  	"100kohm_to_gnd",
  };
  
  enum {
  	MAX5821_THREE_STATE,
  	MAX5821_1KOHM_TO_GND,
  	MAX5821_100KOHM_TO_GND
  };
  
  static int max5821_get_powerdown_mode(struct iio_dev *indio_dev,
  				      const struct iio_chan_spec *chan)
  {
  	struct max5821_data *st = iio_priv(indio_dev);
  
  	return st->powerdown_mode[chan->channel];
  }
  
  static int max5821_set_powerdown_mode(struct iio_dev *indio_dev,
  				      const struct iio_chan_spec *chan,
  				      unsigned int mode)
  {
  	struct max5821_data *st = iio_priv(indio_dev);
  
  	st->powerdown_mode[chan->channel] = mode;
  
  	return 0;
  }
  
  static const struct iio_enum max5821_powerdown_mode_enum = {
  	.items = max5821_powerdown_modes,
  	.num_items = ARRAY_SIZE(max5821_powerdown_modes),
  	.get = max5821_get_powerdown_mode,
  	.set = max5821_set_powerdown_mode,
  };
  
  static ssize_t max5821_read_dac_powerdown(struct iio_dev *indio_dev,
  					  uintptr_t private,
  					  const struct iio_chan_spec *chan,
  					  char *buf)
  {
  	struct max5821_data *st = iio_priv(indio_dev);
  
  	return sprintf(buf, "%d
  ", st->powerdown[chan->channel]);
  }
  
  static int max5821_sync_powerdown_mode(struct max5821_data *data,
  				       const struct iio_chan_spec *chan)
  {
  	u8 outbuf[2];
  
  	outbuf[0] = MAX5821_EXTENDED_COMMAND_MODE;
  
  	if (chan->channel == 0)
  		outbuf[1] = MAX5821_EXTENDED_DAC_A;
  	else
  		outbuf[1] = MAX5821_EXTENDED_DAC_B;
  
  	if (data->powerdown[chan->channel])
  		outbuf[1] |= data->powerdown_mode[chan->channel] + 1;
  	else
  		outbuf[1] |= MAX5821_EXTENDED_POWER_UP;
  
  	return i2c_master_send(data->client, outbuf, 2);
  }
  
  static ssize_t max5821_write_dac_powerdown(struct iio_dev *indio_dev,
  					   uintptr_t private,
  					   const struct iio_chan_spec *chan,
  					   const char *buf, size_t len)
  {
  	struct max5821_data *data = iio_priv(indio_dev);
  	bool powerdown;
  	int ret;
  
  	ret = strtobool(buf, &powerdown);
  	if (ret)
  		return ret;
  
  	data->powerdown[chan->channel] = powerdown;
  
  	ret = max5821_sync_powerdown_mode(data, chan);
  	if (ret < 0)
  		return ret;
  
  	return len;
  }
  
  static const struct iio_chan_spec_ext_info max5821_ext_info[] = {
  	{
  		.name = "powerdown",
  		.read = max5821_read_dac_powerdown,
  		.write = max5821_write_dac_powerdown,
  		.shared = IIO_SEPARATE,
  	},
  	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &max5821_powerdown_mode_enum),
  	IIO_ENUM_AVAILABLE("powerdown_mode", &max5821_powerdown_mode_enum),
  	{ },
  };
  
  #define MAX5821_CHANNEL(chan) {					\
  	.type = IIO_VOLTAGE,					\
  	.indexed = 1,						\
  	.output = 1,						\
  	.channel = (chan),					\
  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
  	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SCALE),	\
  	.ext_info = max5821_ext_info,				\
  }
  
  static const struct iio_chan_spec max5821_channels[] = {
  	MAX5821_CHANNEL(0),
  	MAX5821_CHANNEL(1)
  };
  
  static const u8 max5821_read_dac_command[] = {
  	MAX5821_READ_DAC_A_COMMAND,
  	MAX5821_READ_DAC_B_COMMAND
  };
  
  static const u8 max5821_load_dac_command[] = {
  	MAX5821_LOAD_DAC_A_IN_REG_B,
  	MAX5821_LOAD_DAC_B_IN_REG_A
  };
  
  static int max5821_get_value(struct iio_dev *indio_dev,
  			     int *val, int channel)
  {
  	struct max5821_data *data = iio_priv(indio_dev);
  	struct i2c_client *client = data->client;
  	u8 outbuf[1];
  	u8 inbuf[2];
  	int ret;
  
  	if ((channel != 0) && (channel != 1))
  		return -EINVAL;
  
  	outbuf[0] = max5821_read_dac_command[channel];
  
  	mutex_lock(&data->lock);
  
  	ret = i2c_master_send(client, outbuf, 1);
  	if (ret < 0) {
  		mutex_unlock(&data->lock);
  		return ret;
  	} else if (ret != 1) {
  		mutex_unlock(&data->lock);
  		return -EIO;
  	}
  
  	ret = i2c_master_recv(client, inbuf, 2);
  	if (ret < 0) {
  		mutex_unlock(&data->lock);
  		return ret;
  	} else if (ret != 2) {
  		mutex_unlock(&data->lock);
  		return -EIO;
  	}
  
  	mutex_unlock(&data->lock);
  
  	*val = ((inbuf[0] & 0x0f) << 6) | (inbuf[1] >> 2);
  
  	return IIO_VAL_INT;
  }
  
  static int max5821_set_value(struct iio_dev *indio_dev,
  			     int val, int channel)
  {
  	struct max5821_data *data = iio_priv(indio_dev);
  	struct i2c_client *client = data->client;
  	u8 outbuf[2];
  	int ret;
  
  	if ((val < 0) || (val > 1023))
  		return -EINVAL;
  
  	if ((channel != 0) && (channel != 1))
  		return -EINVAL;
  
  	outbuf[0] = max5821_load_dac_command[channel];
  	outbuf[0] |= val >> 6;
  	outbuf[1] = (val & 0x3f) << 2;
  
  	ret = i2c_master_send(client, outbuf, 2);
  	if (ret < 0)
  		return ret;
  	else if (ret != 2)
  		return -EIO;
  	else
  		return 0;
  }
  
  static int max5821_read_raw(struct iio_dev *indio_dev,
  			   struct iio_chan_spec const *chan,
  			   int *val, int *val2, long mask)
  {
  	struct max5821_data *data = iio_priv(indio_dev);
  
  	switch (mask) {
  	case IIO_CHAN_INFO_RAW:
  		return max5821_get_value(indio_dev, val, chan->channel);
  	case IIO_CHAN_INFO_SCALE:
  		*val = data->vref_mv;
  		*val2 = 10;
  		return IIO_VAL_FRACTIONAL_LOG2;
  	default:
  		return -EINVAL;
  	}
  }
  
  static int max5821_write_raw(struct iio_dev *indio_dev,
  			     struct iio_chan_spec const *chan,
  			     int val, int val2, long mask)
  {
  	if (val2 != 0)
  		return -EINVAL;
  
  	switch (mask) {
  	case IIO_CHAN_INFO_RAW:
  		return max5821_set_value(indio_dev, val, chan->channel);
  	default:
  		return -EINVAL;
  	}
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int max5821_suspend(struct device *dev)
  {
  	u8 outbuf[2] = { MAX5821_EXTENDED_COMMAND_MODE,
  			 MAX5821_EXTENDED_DAC_A |
  			 MAX5821_EXTENDED_DAC_B |
  			 MAX5821_EXTENDED_POWER_DOWN_MODE2 };
  
  	return i2c_master_send(to_i2c_client(dev), outbuf, 2);
  }
  
  static int max5821_resume(struct device *dev)
  {
  	u8 outbuf[2] = { MAX5821_EXTENDED_COMMAND_MODE,
  			 MAX5821_EXTENDED_DAC_A |
  			 MAX5821_EXTENDED_DAC_B |
  			 MAX5821_EXTENDED_POWER_UP };
  
  	return i2c_master_send(to_i2c_client(dev), outbuf, 2);
  }
  
  static SIMPLE_DEV_PM_OPS(max5821_pm_ops, max5821_suspend, max5821_resume);
  #define MAX5821_PM_OPS (&max5821_pm_ops)
  #else
  #define MAX5821_PM_OPS NULL
  #endif /* CONFIG_PM_SLEEP */
  
  static const struct iio_info max5821_info = {
  	.read_raw = max5821_read_raw,
  	.write_raw = max5821_write_raw,
  	.driver_module = THIS_MODULE,
  };
  
  static int max5821_probe(struct i2c_client *client,
  			const struct i2c_device_id *id)
  {
  	struct max5821_data *data;
  	struct iio_dev *indio_dev;
  	u32 tmp;
  	int ret;
  
  	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
  	if (!indio_dev)
  		return -ENOMEM;
  	data = iio_priv(indio_dev);
  	i2c_set_clientdata(client, indio_dev);
  	data->client = client;
  	mutex_init(&data->lock);
  
  	/* max5821 start in powerdown mode 100Kohm to ground */
  	for (tmp = 0; tmp < MAX5821_MAX_DAC_CHANNELS; tmp++) {
  		data->powerdown[tmp] = true;
  		data->powerdown_mode[tmp] = MAX5821_100KOHM_TO_GND;
  	}
  
  	data->vref_reg = devm_regulator_get(&client->dev, "vref");
  	if (IS_ERR(data->vref_reg)) {
  		ret = PTR_ERR(data->vref_reg);
  		dev_err(&client->dev,
  			"Failed to get vref regulator: %d
  ", ret);
  		goto error_free_reg;
  	}
  
  	ret = regulator_enable(data->vref_reg);
  	if (ret) {
  		dev_err(&client->dev,
  			"Failed to enable vref regulator: %d
  ", ret);
  		goto error_free_reg;
  	}
  
  	ret = regulator_get_voltage(data->vref_reg);
  	if (ret < 0) {
  		dev_err(&client->dev,
  			"Failed to get voltage on regulator: %d
  ", ret);
  		goto error_disable_reg;
  	}
  
  	data->vref_mv = ret / 1000;
  
  	indio_dev->name = id->name;
  	indio_dev->dev.parent = &client->dev;
  	indio_dev->num_channels = ARRAY_SIZE(max5821_channels);
  	indio_dev->channels = max5821_channels;
  	indio_dev->modes = INDIO_DIRECT_MODE;
  	indio_dev->info = &max5821_info;
  
  	return iio_device_register(indio_dev);
  
  error_disable_reg:
  	regulator_disable(data->vref_reg);
  
  error_free_reg:
  
  	return ret;
  }
  
  static int max5821_remove(struct i2c_client *client)
  {
  	struct iio_dev *indio_dev = i2c_get_clientdata(client);
  	struct max5821_data *data = iio_priv(indio_dev);
  
  	iio_device_unregister(indio_dev);
  	regulator_disable(data->vref_reg);
  
  	return 0;
  }
  
  static const struct i2c_device_id max5821_id[] = {
  	{ "max5821", ID_MAX5821 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, max5821_id);
  
  static const struct of_device_id max5821_of_match[] = {
  	{ .compatible = "maxim,max5821" },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, max5821_of_match);
  
  static struct i2c_driver max5821_driver = {
  	.driver = {
  		.name	= "max5821",
  		.pm     = MAX5821_PM_OPS,
  	},
  	.probe		= max5821_probe,
  	.remove		= max5821_remove,
  	.id_table	= max5821_id,
  };
  module_i2c_driver(max5821_driver);
  
  MODULE_AUTHOR("Philippe Reynes <tremyfr@yahoo.fr>");
  MODULE_DESCRIPTION("MAX5821 DAC");
  MODULE_LICENSE("GPL v2");