/*
   * Backup battery driver for Wolfson Microelectronics wm831x PMICs
   *
   * Copyright 2009 Wolfson Microelectronics PLC.
   *
   * 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/module.h>
  #include <linux/err.h>
  #include <linux/platform_device.h>
  #include <linux/power_supply.h>
  #include <linux/slab.h>
  
  #include <linux/mfd/wm831x/core.h>
  #include <linux/mfd/wm831x/auxadc.h>
  #include <linux/mfd/wm831x/pmu.h>
  #include <linux/mfd/wm831x/pdata.h>
  
  struct wm831x_backup {
  	struct wm831x *wm831x;
  	struct power_supply backup;
  	char name[20];
  };
  
  static int wm831x_backup_read_voltage(struct wm831x *wm831x,
  				     enum wm831x_auxadc src,
  				     union power_supply_propval *val)
  {
  	int ret;
  
  	ret = wm831x_auxadc_read_uv(wm831x, src);
  	if (ret >= 0)
  		val->intval = ret;
  
  	return ret;
  }
  
  /*********************************************************************
   *		Backup supply properties
   *********************************************************************/
  
  static void wm831x_config_backup(struct wm831x *wm831x)
  {
  	struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
  	struct wm831x_backup_pdata *pdata;
  	int ret, reg;
  
  	if (!wm831x_pdata || !wm831x_pdata->backup) {
  		dev_warn(wm831x->dev,
  			 "No backup battery charger configuration
  ");
  		return;
  	}
  
  	pdata = wm831x_pdata->backup;
  
  	reg = 0;
  
  	if (pdata->charger_enable)
  		reg |= WM831X_BKUP_CHG_ENA | WM831X_BKUP_BATT_DET_ENA;
  	if (pdata->no_constant_voltage)
  		reg |= WM831X_BKUP_CHG_MODE;
  
  	switch (pdata->vlim) {
  	case 2500:
  		break;
  	case 3100:
  		reg |= WM831X_BKUP_CHG_VLIM;
  		break;
  	default:
  		dev_err(wm831x->dev, "Invalid backup voltage limit %dmV
  ",
  			pdata->vlim);
  	}
  
  	switch (pdata->ilim) {
  	case 100:
  		break;
  	case 200:
  		reg |= 1;
  		break;
  	case 300:
  		reg |= 2;
  		break;
  	case 400:
  		reg |= 3;
  		break;
  	default:
  		dev_err(wm831x->dev, "Invalid backup current limit %duA
  ",
  			pdata->ilim);
  	}
  
  	ret = wm831x_reg_unlock(wm831x);
  	if (ret != 0) {
  		dev_err(wm831x->dev, "Failed to unlock registers: %d
  ", ret);
  		return;
  	}
  
  	ret = wm831x_set_bits(wm831x, WM831X_BACKUP_CHARGER_CONTROL,
  			      WM831X_BKUP_CHG_ENA_MASK |
  			      WM831X_BKUP_CHG_MODE_MASK |
  			      WM831X_BKUP_BATT_DET_ENA_MASK |
  			      WM831X_BKUP_CHG_VLIM_MASK |
  			      WM831X_BKUP_CHG_ILIM_MASK,
  			      reg);
  	if (ret != 0)
  		dev_err(wm831x->dev,
  			"Failed to set backup charger config: %d
  ", ret);
  
  	wm831x_reg_lock(wm831x);
  }
  
  static int wm831x_backup_get_prop(struct power_supply *psy,
  				  enum power_supply_property psp,
  				  union power_supply_propval *val)
  {
  	struct wm831x_backup *devdata = dev_get_drvdata(psy->dev->parent);
  	struct wm831x *wm831x = devdata->wm831x;
  	int ret = 0;
  
  	ret = wm831x_reg_read(wm831x, WM831X_BACKUP_CHARGER_CONTROL);
  	if (ret < 0)
  		return ret;
  
  	switch (psp) {
  	case POWER_SUPPLY_PROP_STATUS:
  		if (ret & WM831X_BKUP_CHG_STS)
  			val->intval = POWER_SUPPLY_STATUS_CHARGING;
  		else
  			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
  		break;
  
  	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
  		ret = wm831x_backup_read_voltage(wm831x, WM831X_AUX_BKUP_BATT,
  						val);
  		break;
  
  	case POWER_SUPPLY_PROP_PRESENT:
  		if (ret & WM831X_BKUP_CHG_STS)
  			val->intval = 1;
  		else
  			val->intval = 0;
  		break;
  
  	default:
  		ret = -EINVAL;
  		break;
  	}
  
  	return ret;
  }
  
  static enum power_supply_property wm831x_backup_props[] = {
  	POWER_SUPPLY_PROP_STATUS,
  	POWER_SUPPLY_PROP_VOLTAGE_NOW,
  	POWER_SUPPLY_PROP_PRESENT,
  };
  
  /*********************************************************************
   *		Initialisation
   *********************************************************************/
  
  static int wm831x_backup_probe(struct platform_device *pdev)
  {
  	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
  	struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
  	struct wm831x_backup *devdata;
  	struct power_supply *backup;
  	int ret;
  
  	devdata = devm_kzalloc(&pdev->dev, sizeof(struct wm831x_backup),
  				GFP_KERNEL);
  	if (devdata == NULL)
  		return -ENOMEM;
  
  	devdata->wm831x = wm831x;
  	platform_set_drvdata(pdev, devdata);
  
  	backup = &devdata->backup;
  
  	/* We ignore configuration failures since we can still read
  	 * back the status without enabling the charger (which may
  	 * already be enabled anyway).
  	 */
  	wm831x_config_backup(wm831x);
  
  	if (wm831x_pdata && wm831x_pdata->wm831x_num)
  		snprintf(devdata->name, sizeof(devdata->name),
  			 "wm831x-backup.%d", wm831x_pdata->wm831x_num);
  	else
  		snprintf(devdata->name, sizeof(devdata->name),
  			 "wm831x-backup");
  
  	backup->name = devdata->name;
  	backup->type = POWER_SUPPLY_TYPE_BATTERY;
  	backup->properties = wm831x_backup_props;
  	backup->num_properties = ARRAY_SIZE(wm831x_backup_props);
  	backup->get_property = wm831x_backup_get_prop;
  	ret = power_supply_register(&pdev->dev, backup);
  
  	return ret;
  }
  
  static int wm831x_backup_remove(struct platform_device *pdev)
  {
  	struct wm831x_backup *devdata = platform_get_drvdata(pdev);
  
  	power_supply_unregister(&devdata->backup);
  
  	return 0;
  }
  
  static struct platform_driver wm831x_backup_driver = {
  	.probe = wm831x_backup_probe,
  	.remove = wm831x_backup_remove,
  	.driver = {
  		.name = "wm831x-backup",
  	},
  };
  
  module_platform_driver(wm831x_backup_driver);
  
  MODULE_DESCRIPTION("Backup battery charger driver for WM831x PMICs");
  MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:wm831x-backup");