text: /*
   * Copyright (c) 2016, Prodys S.L.
   *
   * 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 adds support for sbs-charger compilant chips as defined here:
   * http://sbs-forum.org/specs/sbc110.pdf
   *
   * Implemetation based on sbs-battery.c
   */
  
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/err.h>
  #include <linux/power_supply.h>
  #include <linux/i2c.h>
  #include <linux/slab.h>
  #include <linux/interrupt.h>
  #include <linux/gpio.h>
  #include <linux/regmap.h>
  #include <linux/of_gpio.h>
  #include <linux/bitops.h>
  
  #define SBS_CHARGER_REG_SPEC_INFO		0x11
  #define SBS_CHARGER_REG_STATUS			0x13
  #define SBS_CHARGER_REG_ALARM_WARNING		0x16
  
  #define SBS_CHARGER_STATUS_CHARGE_INHIBITED	BIT(1)
  #define SBS_CHARGER_STATUS_RES_COLD		BIT(9)
  #define SBS_CHARGER_STATUS_RES_HOT		BIT(10)
  #define SBS_CHARGER_STATUS_BATTERY_PRESENT	BIT(14)
  #define SBS_CHARGER_STATUS_AC_PRESENT		BIT(15)
  
  #define SBS_CHARGER_POLL_TIME			500
  
  struct sbs_info {
  	struct i2c_client		*client;
  	struct power_supply		*power_supply;
  	struct regmap			*regmap;
  	struct delayed_work		work;
  	unsigned int			last_state;
  };
  
  static int sbs_get_property(struct power_supply *psy,
  			    enum power_supply_property psp,
  			    union power_supply_propval *val)
  {
  	struct sbs_info *chip = power_supply_get_drvdata(psy);
  	unsigned int reg;
  
  	reg = chip->last_state;
  
  	switch (psp) {
  	case POWER_SUPPLY_PROP_PRESENT:
  		val->intval = !!(reg & SBS_CHARGER_STATUS_BATTERY_PRESENT);
  		break;
  
  	case POWER_SUPPLY_PROP_ONLINE:
  		val->intval = !!(reg & SBS_CHARGER_STATUS_AC_PRESENT);
  		break;
  
  	case POWER_SUPPLY_PROP_STATUS:
  		val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
  
  		if (!(reg & SBS_CHARGER_STATUS_BATTERY_PRESENT))
  			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
  		else if (reg & SBS_CHARGER_STATUS_AC_PRESENT &&
  			 !(reg & SBS_CHARGER_STATUS_CHARGE_INHIBITED))
  			val->intval = POWER_SUPPLY_STATUS_CHARGING;
  		else
  			val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
  
  		break;
  
  	case POWER_SUPPLY_PROP_HEALTH:
  		if (reg & SBS_CHARGER_STATUS_RES_COLD)
  			val->intval = POWER_SUPPLY_HEALTH_COLD;
  		if (reg & SBS_CHARGER_STATUS_RES_HOT)
  			val->intval = POWER_SUPPLY_HEALTH_OVERHEAT;
  		else
  			val->intval = POWER_SUPPLY_HEALTH_GOOD;
  
  		break;
  
  	default:
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static int sbs_check_state(struct sbs_info *chip)
  {
  	unsigned int reg;
  	int ret;
  
  	ret = regmap_read(chip->regmap, SBS_CHARGER_REG_STATUS, &reg);
  	if (!ret && reg != chip->last_state) {
  		chip->last_state = reg;
  		power_supply_changed(chip->power_supply);
  		return 1;
  	}
  
  	return 0;
  }
  
  static void sbs_delayed_work(struct work_struct *work)
  {
  	struct sbs_info *chip = container_of(work, struct sbs_info, work.work);
  
  	sbs_check_state(chip);
  
  	schedule_delayed_work(&chip->work,
  			      msecs_to_jiffies(SBS_CHARGER_POLL_TIME));
  }
  
  static irqreturn_t sbs_irq_thread(int irq, void *data)
  {
  	struct sbs_info *chip = data;
  	int ret;
  
  	ret = sbs_check_state(chip);
  
  	return ret ? IRQ_HANDLED : IRQ_NONE;
  }
  
  static enum power_supply_property sbs_properties[] = {
  	POWER_SUPPLY_PROP_STATUS,
  	POWER_SUPPLY_PROP_PRESENT,
  	POWER_SUPPLY_PROP_ONLINE,
  	POWER_SUPPLY_PROP_HEALTH,
  };
  
  static bool sbs_readable_reg(struct device *dev, unsigned int reg)
  {
  	if (reg < SBS_CHARGER_REG_SPEC_INFO)
  		return false;
  	else
  		return true;
  }
  
  static bool sbs_volatile_reg(struct device *dev, unsigned int reg)
  {
  	switch (reg) {
  	case SBS_CHARGER_REG_STATUS:
  		return true;
  	}
  
  	return false;
  }
  
  static const struct regmap_config sbs_regmap = {
  	.reg_bits	= 8,
  	.val_bits	= 16,
  	.max_register	= SBS_CHARGER_REG_ALARM_WARNING,
  	.readable_reg	= sbs_readable_reg,
  	.volatile_reg	= sbs_volatile_reg,
  	.val_format_endian = REGMAP_ENDIAN_LITTLE, /* since based on SMBus */
  };
  
  static const struct power_supply_desc sbs_desc = {
  	.name = "sbs-charger",
  	.type = POWER_SUPPLY_TYPE_MAINS,
  	.properties = sbs_properties,
  	.num_properties = ARRAY_SIZE(sbs_properties),
  	.get_property = sbs_get_property,
  };
  
  static int sbs_probe(struct i2c_client *client,
  		     const struct i2c_device_id *id)
  {
  	struct power_supply_config psy_cfg = {};
  	struct sbs_info *chip;
  	int ret, val;
  
  	chip = devm_kzalloc(&client->dev, sizeof(struct sbs_info), GFP_KERNEL);
  	if (!chip)
  		return -ENOMEM;
  
  	chip->client = client;
  	psy_cfg.of_node = client->dev.of_node;
  	psy_cfg.drv_data = chip;
  
  	i2c_set_clientdata(client, chip);
  
  	chip->regmap = devm_regmap_init_i2c(client, &sbs_regmap);
  	if (IS_ERR(chip->regmap))
  		return PTR_ERR(chip->regmap);
  
  	/*
  	 * Before we register, we need to make sure we can actually talk
  	 * to the battery.
  	 */
  	ret = regmap_read(chip->regmap, SBS_CHARGER_REG_STATUS, &val);
  	if (ret) {
  		dev_err(&client->dev, "Failed to get device status\n");
  		return ret;
  	}
  	chip->last_state = val;
  
  	chip->power_supply = devm_power_supply_register(&client->dev, &sbs_desc,
  							&psy_cfg);
  	if (IS_ERR(chip->power_supply)) {
  		dev_err(&client->dev, "Failed to register power supply\n");
  		return PTR_ERR(chip->power_supply);
  	}
  
  	/*
  	 * The sbs-charger spec doesn't impose the use of an interrupt. So in
  	 * the case it wasn't provided we use polling in order get the charger's
  	 * status.
  	 */
  	if (client->irq) {
  		ret = devm_request_threaded_irq(&client->dev, client->irq,
  					NULL, sbs_irq_thread,
  					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
  					dev_name(&client->dev), chip);
  		if (ret) {
  			dev_err(&client->dev, "Failed to request irq, %d\n", ret);
  			return ret;
  		}
  	} else {
  		INIT_DELAYED_WORK(&chip->work, sbs_delayed_work);
  		schedule_delayed_work(&chip->work,
  				      msecs_to_jiffies(SBS_CHARGER_POLL_TIME));
  	}
  
  	dev_info(&client->dev,
  		 "%s: smart charger device registered\n", client->name);
  
  	return 0;
  }
  
  static int sbs_remove(struct i2c_client *client)
  {
  	struct sbs_info *chip = i2c_get_clientdata(client);
  
  	cancel_delayed_work_sync(&chip->work);
  
  	return 0;
  }
  
  #ifdef CONFIG_OF
  static const struct of_device_id sbs_dt_ids[] = {
  	{ .compatible = "sbs,sbs-charger" },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, sbs_dt_ids);
  #endif
  
  static const struct i2c_device_id sbs_id[] = {
  	{ "sbs-charger", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, sbs_id);
  
  static struct i2c_driver sbs_driver = {
  	.probe		= sbs_probe,
  	.remove		= sbs_remove,
  	.id_table	= sbs_id,
  	.driver = {
  		.name	= "sbs-charger",
  		.of_match_table = of_match_ptr(sbs_dt_ids),
  	},
  };
  module_i2c_driver(sbs_driver);
  
  MODULE_AUTHOR("Nicolas Saenz Julienne <nicolassaenzj@gmail.com>");
  MODULE_DESCRIPTION("SBS smart charger driver");
  MODULE_LICENSE("GPL v2");
  