/*
   * Nokia RX-51 battery driver
   *
   * Copyright (C) 2012  Pali Rohár <pali.rohar@gmail.com>
   *
   * 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.,
   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
   */
  
  #include <linux/module.h>
  #include <linux/param.h>
  #include <linux/platform_device.h>
  #include <linux/power_supply.h>
  #include <linux/slab.h>
  #include <linux/i2c/twl4030-madc.h>
  
  /* RX51 specific channels */
  #define TWL4030_MADC_BTEMP_RX51	TWL4030_MADC_ADCIN0
  #define TWL4030_MADC_BCI_RX51	TWL4030_MADC_ADCIN4
  
  struct rx51_device_info {
  	struct device *dev;
  	struct power_supply bat;
  };
  
  /*
   * Read ADCIN channel value, code copied from maemo kernel
   */
  static int rx51_battery_read_adc(int channel)
  {
  	struct twl4030_madc_request req;
  
  	req.channels = channel;
  	req.do_avg = 1;
  	req.method = TWL4030_MADC_SW1;
  	req.func_cb = NULL;
  	req.type = TWL4030_MADC_WAIT;
  	req.raw = true;
  
  	if (twl4030_madc_conversion(&req) <= 0)
  		return -ENODATA;
  
  	return req.rbuf[ffs(channel) - 1];
  }
  
  /*
   * Read ADCIN channel 12 (voltage) and convert RAW value to micro voltage
   * This conversion formula was extracted from maemo program bsi-read
   */
  static int rx51_battery_read_voltage(struct rx51_device_info *di)
  {
  	int voltage = rx51_battery_read_adc(TWL4030_MADC_VBAT);
  
  	if (voltage < 0)
  		return voltage;
  
  	return 1000 * (10000 * voltage / 1705);
  }
  
  /*
   * Temperature look-up tables
   * TEMP = (1/(t1 + 1/298) - 273.15)
   * Where t1 = (1/B) * ln((RAW_ADC_U * 2.5)/(R * I * 255))
   * Formula is based on experimental data, RX-51 CAL data, maemo program bme
   * and formula from da9052 driver with values R = 100, B = 3380, I = 0.00671
   */
  
  /*
   * Table1 (temperature for first 25 RAW values)
   * Usage: TEMP = rx51_temp_table1[RAW]
   *   RAW is between 1 and 24
   *   TEMP is between 201 C and 55 C
   */
  static u8 rx51_temp_table1[] = {
  	255, 201, 159, 138, 124, 114, 106,  99,  94,  89,  85,  82,  78,  75,
  	 73,  70,  68,  66,  64,  62,  61,  59,  57,  56,  55
  };
  
  /*
   * Table2 (lowest RAW value for temperature)
   * Usage: RAW = rx51_temp_table2[TEMP-rx51_temp_table2_first]
   *   TEMP is between 53 C and -32 C
   *   RAW is between 25 and 993
   */
  #define rx51_temp_table2_first 53
  static u16 rx51_temp_table2[] = {
  	 25,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,  37,  39,
  	 40,  41,  43,  44,  46,  48,  49,  51,  53,  55,  57,  59,  61,  64,
  	 66,  69,  71,  74,  77,  80,  83,  86,  90,  94,  97, 101, 106, 110,
  	115, 119, 125, 130, 136, 141, 148, 154, 161, 168, 176, 184, 202, 211,
  	221, 231, 242, 254, 266, 279, 293, 308, 323, 340, 357, 375, 395, 415,
  	437, 460, 485, 511, 539, 568, 600, 633, 669, 706, 747, 790, 836, 885,
  	937, 993, 1024
  };
  
  /*
   * Read ADCIN channel 0 (battery temp) and convert value to tenths of Celsius
   * Use Temperature look-up tables for conversation
   */
  static int rx51_battery_read_temperature(struct rx51_device_info *di)
  {
  	int min = 0;
  	int max = ARRAY_SIZE(rx51_temp_table2) - 1;
  	int raw = rx51_battery_read_adc(TWL4030_MADC_BTEMP_RX51);
  
  	/* Zero and negative values are undefined */
  	if (raw <= 0)
  		return INT_MAX;
  
  	/* ADC channels are 10 bit, higher value are undefined */
  	if (raw >= (1 << 10))
  		return INT_MIN;
  
  	/* First check for temperature in first direct table */
  	if (raw < ARRAY_SIZE(rx51_temp_table1))
  		return rx51_temp_table1[raw] * 10;
  
  	/* Binary search RAW value in second inverse table */
  	while (max - min > 1) {
  		int mid = (max + min) / 2;
  		if (rx51_temp_table2[mid] <= raw)
  			min = mid;
  		else if (rx51_temp_table2[mid] > raw)
  			max = mid;
  		if (rx51_temp_table2[mid] == raw)
  			break;
  	}
  
  	return (rx51_temp_table2_first - min) * 10;
  }
  
  /*
   * Read ADCIN channel 4 (BSI) and convert RAW value to micro Ah
   * This conversion formula was extracted from maemo program bsi-read
   */
  static int rx51_battery_read_capacity(struct rx51_device_info *di)
  {
  	int capacity = rx51_battery_read_adc(TWL4030_MADC_BCI_RX51);
  
  	if (capacity < 0)
  		return capacity;
  
  	return 1280 * (1200 * capacity)/(1024 - capacity);
  }
  
  /*
   * Return power_supply property
   */
  static int rx51_battery_get_property(struct power_supply *psy,
  					enum power_supply_property psp,
  					union power_supply_propval *val)
  {
  	struct rx51_device_info *di = container_of((psy),
  				struct rx51_device_info, bat);
  
  	switch (psp) {
  	case POWER_SUPPLY_PROP_TECHNOLOGY:
  		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
  		break;
  	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
  		val->intval = 4200000;
  		break;
  	case POWER_SUPPLY_PROP_PRESENT:
  		val->intval = rx51_battery_read_voltage(di) ? 1 : 0;
  		break;
  	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
  		val->intval = rx51_battery_read_voltage(di);
  		break;
  	case POWER_SUPPLY_PROP_TEMP:
  		val->intval = rx51_battery_read_temperature(di);
  		break;
  	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
  		val->intval = rx51_battery_read_capacity(di);
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	if (val->intval == INT_MAX || val->intval == INT_MIN)
  		return -EINVAL;
  
  	return 0;
  }
  
  static enum power_supply_property rx51_battery_props[] = {
  	POWER_SUPPLY_PROP_TECHNOLOGY,
  	POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
  	POWER_SUPPLY_PROP_PRESENT,
  	POWER_SUPPLY_PROP_VOLTAGE_NOW,
  	POWER_SUPPLY_PROP_TEMP,
  	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
  };
  
  static int rx51_battery_probe(struct platform_device *pdev)
  {
  	struct rx51_device_info *di;
  	int ret;
  
  	di = devm_kzalloc(&pdev->dev, sizeof(*di), GFP_KERNEL);
  	if (!di)
  		return -ENOMEM;
  
  	platform_set_drvdata(pdev, di);
  
  	di->bat.name = dev_name(&pdev->dev);
  	di->bat.type = POWER_SUPPLY_TYPE_BATTERY;
  	di->bat.properties = rx51_battery_props;
  	di->bat.num_properties = ARRAY_SIZE(rx51_battery_props);
  	di->bat.get_property = rx51_battery_get_property;
  
  	ret = power_supply_register(di->dev, &di->bat);
  	if (ret)
  		return ret;
  
  	return 0;
  }
  
  static int rx51_battery_remove(struct platform_device *pdev)
  {
  	struct rx51_device_info *di = platform_get_drvdata(pdev);
  
  	power_supply_unregister(&di->bat);
  
  	return 0;
  }
  
  static struct platform_driver rx51_battery_driver = {
  	.probe = rx51_battery_probe,
  	.remove = rx51_battery_remove,
  	.driver = {
  		.name = "rx51-battery",
  		.owner = THIS_MODULE,
  	},
  };
  module_platform_driver(rx51_battery_driver);
  
  MODULE_ALIAS("platform:rx51-battery");
  MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
  MODULE_DESCRIPTION("Nokia RX-51 battery driver");
  MODULE_LICENSE("GPL");