/*
   * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
   * (C) 2007 EADS Astrium
   *
   * This driver is based on the lm75 and other lm_sensors/hwmon drivers
   *
   * Written by Steve Hardy <shardy@redhat.com>
   *
   * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
   *
   * For further information, see the Documentation/hwmon/ads7828 file.
   *
   * 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/err.h>
  #include <linux/hwmon.h>
  #include <linux/hwmon-sysfs.h>
  #include <linux/i2c.h>
  #include <linux/init.h>
  #include <linux/jiffies.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/platform_data/ads7828.h>
  #include <linux/slab.h>
  
  /* The ADS7828 registers */
  #define ADS7828_NCH		8	/* 8 channels supported */
  #define ADS7828_CMD_SD_SE	0x80	/* Single ended inputs */
  #define ADS7828_CMD_PD1		0x04	/* Internal vref OFF && A/D ON */
  #define ADS7828_CMD_PD3		0x0C	/* Internal vref ON && A/D ON */
  #define ADS7828_INT_VREF_MV	2500	/* Internal vref is 2.5V, 2500mV */
  #define ADS7828_EXT_VREF_MV_MIN	50	/* External vref min value 0.05V */
  #define ADS7828_EXT_VREF_MV_MAX	5250	/* External vref max value 5.25V */
  
  /* List of supported devices */
  enum ads7828_chips { ads7828, ads7830 };
  
  /* Client specific data */
  struct ads7828_data {
  	struct device *hwmon_dev;
  	struct mutex update_lock;	/* Mutex protecting updates */
  	unsigned long last_updated;	/* Last updated time (in jiffies) */
  	u16 adc_input[ADS7828_NCH];	/* ADS7828_NCH samples */
  	bool valid;			/* Validity flag */
  	bool diff_input;		/* Differential input */
  	bool ext_vref;			/* External voltage reference */
  	unsigned int vref_mv;		/* voltage reference value */
  	u8 cmd_byte;			/* Command byte without channel bits */
  	unsigned int lsb_resol;		/* Resolution of the ADC sample LSB */
  	s32 (*read_channel)(const struct i2c_client *client, u8 command);
  };
  
  /* Command byte C2,C1,C0 - see datasheet */
  static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
  {
  	return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
  }
  
  /* Update data for the device (all 8 channels) */
  static struct ads7828_data *ads7828_update_device(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct ads7828_data *data = i2c_get_clientdata(client);
  
  	mutex_lock(&data->update_lock);
  
  	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
  			|| !data->valid) {
  		unsigned int ch;
  		dev_dbg(&client->dev, "Starting ads7828 update
  ");
  
  		for (ch = 0; ch < ADS7828_NCH; ch++) {
  			u8 cmd = ads7828_cmd_byte(data->cmd_byte, ch);
  			data->adc_input[ch] = data->read_channel(client, cmd);
  		}
  		data->last_updated = jiffies;
  		data->valid = true;
  	}
  
  	mutex_unlock(&data->update_lock);
  
  	return data;
  }
  
  /* sysfs callback function */
  static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da,
  			       char *buf)
  {
  	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  	struct ads7828_data *data = ads7828_update_device(dev);
  	unsigned int value = DIV_ROUND_CLOSEST(data->adc_input[attr->index] *
  					       data->lsb_resol, 1000);
  
  	return sprintf(buf, "%d
  ", value);
  }
  
  static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
  static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
  static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
  static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
  static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
  static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
  static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
  static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
  
  static struct attribute *ads7828_attributes[] = {
  	&sensor_dev_attr_in0_input.dev_attr.attr,
  	&sensor_dev_attr_in1_input.dev_attr.attr,
  	&sensor_dev_attr_in2_input.dev_attr.attr,
  	&sensor_dev_attr_in3_input.dev_attr.attr,
  	&sensor_dev_attr_in4_input.dev_attr.attr,
  	&sensor_dev_attr_in5_input.dev_attr.attr,
  	&sensor_dev_attr_in6_input.dev_attr.attr,
  	&sensor_dev_attr_in7_input.dev_attr.attr,
  	NULL
  };
  
  static const struct attribute_group ads7828_group = {
  	.attrs = ads7828_attributes,
  };
  
  static int ads7828_remove(struct i2c_client *client)
  {
  	struct ads7828_data *data = i2c_get_clientdata(client);
  
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_group(&client->dev.kobj, &ads7828_group);
  
  	return 0;
  }
  
  static int ads7828_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)
  {
  	struct ads7828_platform_data *pdata = dev_get_platdata(&client->dev);
  	struct ads7828_data *data;
  	int err;
  
  	data = devm_kzalloc(&client->dev, sizeof(struct ads7828_data),
  			    GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	if (pdata) {
  		data->diff_input = pdata->diff_input;
  		data->ext_vref = pdata->ext_vref;
  		if (data->ext_vref)
  			data->vref_mv = pdata->vref_mv;
  	}
  
  	/* Bound Vref with min/max values if it was provided */
  	if (data->vref_mv)
  		data->vref_mv = clamp_val(data->vref_mv,
  					  ADS7828_EXT_VREF_MV_MIN,
  					  ADS7828_EXT_VREF_MV_MAX);
  	else
  		data->vref_mv = ADS7828_INT_VREF_MV;
  
  	/* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
  	if (id->driver_data == ads7828) {
  		data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096);
  		data->read_channel = i2c_smbus_read_word_swapped;
  	} else {
  		data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 256);
  		data->read_channel = i2c_smbus_read_byte_data;
  	}
  
  	data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
  	if (!data->diff_input)
  		data->cmd_byte |= ADS7828_CMD_SD_SE;
  
  	i2c_set_clientdata(client, data);
  	mutex_init(&data->update_lock);
  
  	err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
  	if (err)
  		return err;
  
  	data->hwmon_dev = hwmon_device_register(&client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);
  		goto error;
  	}
  
  	return 0;
  
  error:
  	sysfs_remove_group(&client->dev.kobj, &ads7828_group);
  	return err;
  }
  
  static const struct i2c_device_id ads7828_device_ids[] = {
  	{ "ads7828", ads7828 },
  	{ "ads7830", ads7830 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
  
  static struct i2c_driver ads7828_driver = {
  	.driver = {
  		.name = "ads7828",
  	},
  
  	.id_table = ads7828_device_ids,
  	.probe = ads7828_probe,
  	.remove = ads7828_remove,
  };
  
  module_i2c_driver(ads7828_driver);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
  MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");