/*
   * ads1015.c - lm_sensors driver for ads1015 12-bit 4-input ADC
   * (C) Copyright 2010
   * Dirk Eibach, Guntermann & Drunck GmbH <eibach@gdsys.de>
   *
   * Based on the ads7828 driver by Steve Hardy.
   *
   * Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads1015.pdf
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/delay.h>
  #include <linux/i2c.h>
  #include <linux/hwmon.h>
  #include <linux/hwmon-sysfs.h>
  #include <linux/err.h>
  #include <linux/mutex.h>

  #include <linux/of_device.h>

  #include <linux/of.h>

  #include <linux/platform_data/ads1015.h>

  
  /* ADS1015 registers */
  enum {
  	ADS1015_CONVERSION = 0,
  	ADS1015_CONFIG = 1,
  };
  
  /* PGA fullscale voltages in mV */
  static const unsigned int fullscale_table[8] = {
  	6144, 4096, 2048, 1024, 512, 256, 256, 256 };

  /* Data rates in samples per second */

  static const unsigned int data_rate_table_1015[8] = {
  	128, 250, 490, 920, 1600, 2400, 3300, 3300
  };
  
  static const unsigned int data_rate_table_1115[8] = {
  	8, 16, 32, 64, 128, 250, 475, 860
  };

  #define ADS1015_DEFAULT_CHANNELS 0xff

  #define ADS1015_DEFAULT_PGA 2
  #define ADS1015_DEFAULT_DATA_RATE 4

  enum ads1015_chips {
  	ads1015,
  	ads1115,
  };

  struct ads1015_data {
  	struct device *hwmon_dev;
  	struct mutex update_lock; /* mutex protect updates */

  	struct ads1015_channel_data channel_data[ADS1015_CHANNELS];

  	enum ads1015_chips id;

  };

  static int ads1015_read_adc(struct i2c_client *client, unsigned int channel)

  {
  	u16 config;

  	struct ads1015_data *data = i2c_get_clientdata(client);

  	unsigned int pga = data->channel_data[channel].pga;

  	unsigned int data_rate = data->channel_data[channel].data_rate;
  	unsigned int conversion_time_ms;

  	const unsigned int * const rate_table = data->id == ads1115 ?
  		data_rate_table_1115 : data_rate_table_1015;

  	int res;
  
  	mutex_lock(&data->update_lock);

  	/* get channel parameters */

  	res = i2c_smbus_read_word_swapped(client, ADS1015_CONFIG);

  	if (res < 0)
  		goto err_unlock;
  	config = res;

  	conversion_time_ms = DIV_ROUND_UP(1000, rate_table[data_rate]);

  	/* setup and start single conversion */
  	config &= 0x001f;
  	config |= (1 << 15) | (1 << 8);
  	config |= (channel & 0x0007) << 12;
  	config |= (pga & 0x0007) << 9;
  	config |= (data_rate & 0x0007) << 5;

  	res = i2c_smbus_write_word_swapped(client, ADS1015_CONFIG, config);

  	if (res < 0)
  		goto err_unlock;

  
  	/* wait until conversion finished */
  	msleep(conversion_time_ms);

  	res = i2c_smbus_read_word_swapped(client, ADS1015_CONFIG);

  	if (res < 0)
  		goto err_unlock;
  	config = res;
  	if (!(config & (1 << 15))) {
  		/* conversion not finished in time */

  		res = -EIO;
  		goto err_unlock;
  	}

  	res = i2c_smbus_read_word_swapped(client, ADS1015_CONVERSION);

  
  err_unlock:
  	mutex_unlock(&data->update_lock);
  	return res;
  }

  static int ads1015_reg_to_mv(struct i2c_client *client, unsigned int channel,
  			     s16 reg)
  {
  	struct ads1015_data *data = i2c_get_clientdata(client);
  	unsigned int pga = data->channel_data[channel].pga;
  	int fullscale = fullscale_table[pga];

  	const int mask = data->id == ads1115 ? 0x7fff : 0x7ff0;

  	return DIV_ROUND_CLOSEST(reg * fullscale, mask);

  }

  /* sysfs callback function */
  static ssize_t show_in(struct device *dev, struct device_attribute *da,
  	char *buf)
  {
  	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  	struct i2c_client *client = to_i2c_client(dev);

  	int res;

  	int index = attr->index;

  	res = ads1015_read_adc(client, index);
  	if (res < 0)
  		return res;

  	return sprintf(buf, "%d
  ", ads1015_reg_to_mv(client, index, res));

  }

  static const struct sensor_device_attribute ads1015_in[] = {
  	SENSOR_ATTR(in0_input, S_IRUGO, show_in, NULL, 0),
  	SENSOR_ATTR(in1_input, S_IRUGO, show_in, NULL, 1),
  	SENSOR_ATTR(in2_input, S_IRUGO, show_in, NULL, 2),
  	SENSOR_ATTR(in3_input, S_IRUGO, show_in, NULL, 3),
  	SENSOR_ATTR(in4_input, S_IRUGO, show_in, NULL, 4),
  	SENSOR_ATTR(in5_input, S_IRUGO, show_in, NULL, 5),
  	SENSOR_ATTR(in6_input, S_IRUGO, show_in, NULL, 6),
  	SENSOR_ATTR(in7_input, S_IRUGO, show_in, NULL, 7),

  };
  
  /*
   * Driver interface
   */
  
  static int ads1015_remove(struct i2c_client *client)
  {
  	struct ads1015_data *data = i2c_get_clientdata(client);

  	int k;

  	hwmon_device_unregister(data->hwmon_dev);

  	for (k = 0; k < ADS1015_CHANNELS; ++k)

  		device_remove_file(&client->dev, &ads1015_in[k].dev_attr);

  	return 0;
  }

  #ifdef CONFIG_OF

  static int ads1015_get_channels_config_of(struct i2c_client *client)
  {
  	struct ads1015_data *data = i2c_get_clientdata(client);
  	struct device_node *node;
  
  	if (!client->dev.of_node
  	    || !of_get_next_child(client->dev.of_node, NULL))
  		return -EINVAL;
  
  	for_each_child_of_node(client->dev.of_node, node) {

  		u32 pval;

  		unsigned int channel;
  		unsigned int pga = ADS1015_DEFAULT_PGA;
  		unsigned int data_rate = ADS1015_DEFAULT_DATA_RATE;

  		if (of_property_read_u32(node, "reg", &pval)) {

  			dev_err(&client->dev, "invalid reg on %pOF
  ", node);

  			continue;
  		}

  		channel = pval;

  		if (channel >= ADS1015_CHANNELS) {

  			dev_err(&client->dev,

  				"invalid channel index %d on %pOF
  ",
  				channel, node);

  			continue;
  		}

  		if (!of_property_read_u32(node, "ti,gain", &pval)) {
  			pga = pval;

  			if (pga > 6) {

  				dev_err(&client->dev, "invalid gain on %pOF
  ",
  					node);

  				return -EINVAL;

  			}
  		}

  		if (!of_property_read_u32(node, "ti,datarate", &pval)) {
  			data_rate = pval;

  			if (data_rate > 7) {
  				dev_err(&client->dev,

  					"invalid data_rate on %pOF
  ", node);

  				return -EINVAL;

  			}
  		}
  
  		data->channel_data[channel].enabled = true;
  		data->channel_data[channel].pga = pga;
  		data->channel_data[channel].data_rate = data_rate;
  	}
  
  	return 0;
  }

  #endif

  static void ads1015_get_channels_config(struct i2c_client *client)
  {
  	unsigned int k;
  	struct ads1015_data *data = i2c_get_clientdata(client);
  	struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);

  	/* prefer platform data */

  	if (pdata) {
  		memcpy(data->channel_data, pdata->channel_data,
  		       sizeof(data->channel_data));
  		return;
  	}

  
  #ifdef CONFIG_OF

  	if (!ads1015_get_channels_config_of(client))
  		return;

  #endif
  
  	/* fallback on default configuration */

  	for (k = 0; k < ADS1015_CHANNELS; ++k) {
  		data->channel_data[k].enabled = true;
  		data->channel_data[k].pga = ADS1015_DEFAULT_PGA;
  		data->channel_data[k].data_rate = ADS1015_DEFAULT_DATA_RATE;
  	}

  }
  
  static int ads1015_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)
  {
  	struct ads1015_data *data;
  	int err;

  	unsigned int k;

  	data = devm_kzalloc(&client->dev, sizeof(struct ads1015_data),
  			    GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;

  
  	if (client->dev.of_node)
  		data->id = (enum ads1015_chips)
  			of_device_get_match_data(&client->dev);
  	else
  		data->id = id->driver_data;

  	i2c_set_clientdata(client, data);
  	mutex_init(&data->update_lock);
  
  	/* build sysfs attribute group */

  	ads1015_get_channels_config(client);
  	for (k = 0; k < ADS1015_CHANNELS; ++k) {
  		if (!data->channel_data[k].enabled)

  			continue;

  		err = device_create_file(&client->dev, &ads1015_in[k].dev_attr);
  		if (err)

  			goto exit_remove;

  	}

  
  	data->hwmon_dev = hwmon_device_register(&client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);
  		goto exit_remove;
  	}
  
  	return 0;
  
  exit_remove:

  	for (k = 0; k < ADS1015_CHANNELS; ++k)

  		device_remove_file(&client->dev, &ads1015_in[k].dev_attr);

  	return err;
  }
  
  static const struct i2c_device_id ads1015_id[] = {

  	{ "ads1015",  ads1015},
  	{ "ads1115",  ads1115},

  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, ads1015_id);

  static const struct of_device_id ads1015_of_match[] = {
  	{
  		.compatible = "ti,ads1015",
  		.data = (void *)ads1015
  	},
  	{
  		.compatible = "ti,ads1115",
  		.data = (void *)ads1115
  	},
  	{ },
  };
  MODULE_DEVICE_TABLE(of, ads1015_of_match);

  static struct i2c_driver ads1015_driver = {
  	.driver = {
  		.name = "ads1015",

  		.of_match_table = of_match_ptr(ads1015_of_match),

  	},
  	.probe = ads1015_probe,
  	.remove = ads1015_remove,
  	.id_table = ads1015_id,
  };

  module_i2c_driver(ads1015_driver);

  
  MODULE_AUTHOR("Dirk Eibach <eibach@gdsys.de>");
  MODULE_DESCRIPTION("ADS1015 driver");
  MODULE_LICENSE("GPL");