drivers/power/gta01_battery.c

   1 /*
   2  * Dumb driver for gta01 battery
   3  *
   4  * Copyright 2009 Openmoko, Inc
   5  * Balaji Rao <balajirrao@openmoko.org>
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/param.h>
  10 #include <linux/delay.h>
  11 #include <linux/workqueue.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/power_supply.h>
  14 #include <linux/gta01_battery.h>
  15
  16 struct gta01_battery {
  17         struct power_supply psy;
  18         struct gta01_bat_platform_data *pdata;
  19 };
  20
  21 static enum power_supply_property gta01_bat_props[] = {
  22         POWER_SUPPLY_PROP_PRESENT,
  23         POWER_SUPPLY_PROP_STATUS,
  24         POWER_SUPPLY_PROP_VOLTAGE_NOW,
  25         POWER_SUPPLY_PROP_CURRENT_NOW,
  26         POWER_SUPPLY_PROP_CAPACITY,
  27         POWER_SUPPLY_PROP_CHARGE_FULL,
  28         POWER_SUPPLY_PROP_CHARGE_NOW,
  29 };
  30
  31 /* Capacity of typical BL-5C dumb battery */
  32 #define GTA01_BAT_CHARGE_FULL   850000
  33
  34 static int gta01_bat_voltscale(int volt)
  35 {
  36         /* This table is suggested by SpeedEvil based on analysis of
  37          * experimental data */
  38         static const int lut[][2] = {
  39                 { 4120, 100 },
  40                 { 3900, 60 },
  41                 { 3740, 25 },
  42                 { 3600, 5 },
  43                 { 3000, 0 } };
  44         int i, res = 0;
  45
  46         if (volt > lut[0][0])
  47                 res = lut[0][1];
  48         else
  49                 for (i = 0; lut[i][1]; i++) {
  50                         if (volt <= lut[i][0] && volt >= lut[i+1][0]) {
  51                                 res = lut[i][1] - (lut[i][0]-volt)*
  52                                         (lut[i][1]-lut[i+1][1])/
  53                                         (lut[i][0]-lut[i+1][0]);
  54                                 break;
  55                         }
  56                 }
  57         return res;
  58 }
  59
  60 static int gta01_bat_get_property(struct power_supply *psy,
  61                                        enum power_supply_property psp,
  62                                        union power_supply_propval *val)
  63 {
  64         struct gta01_battery *bat = container_of(psy, struct gta01_battery, psy);
  65
  66         switch(psp) {
  67         case POWER_SUPPLY_PROP_STATUS:
  68                 if (bat->pdata->get_charging_status)
  69                         if (bat->pdata->get_charging_status())
  70                                 val->intval = POWER_SUPPLY_STATUS_CHARGING;
  71                         else
  72                                 val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
  73                 else
  74                         val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
  75                 break;
  76         case POWER_SUPPLY_PROP_VOLTAGE_NOW:
  77                 if (bat->pdata->get_voltage)
  78                         val->intval = bat->pdata->get_voltage();
  79                 else
  80                         val->intval = 0;
  81                 break;
  82         case POWER_SUPPLY_PROP_CURRENT_NOW:
  83                 if (bat->pdata->get_current)
  84                         val->intval = bat->pdata->get_current();
  85                 else
  86                         val->intval = 0;
  87                 break;
  88         case POWER_SUPPLY_PROP_PRESENT:
  89                 val->intval = 1; /* You must never run GTA01 without battery. */
  90                 break;
  91         case POWER_SUPPLY_PROP_CHARGE_NOW:
  92                 if (bat->pdata->get_voltage) {
  93                         int perc = gta01_bat_voltscale(
  94                                         bat->pdata->get_voltage()/1000);
  95                         val->intval = perc * GTA01_BAT_CHARGE_FULL / 100;
  96                 } else
  97                         val->intval = 0;
  98                 break;
  99         case POWER_SUPPLY_PROP_CAPACITY:
 100                 if (bat->pdata->get_voltage)
 101                         val->intval = gta01_bat_voltscale(
 102                                         bat->pdata->get_voltage()/1000);
 103                 else
 104                         val->intval = 0;
 105                 break;
 106         case POWER_SUPPLY_PROP_CHARGE_FULL:
 107                 val->intval = GTA01_BAT_CHARGE_FULL;
 108                 break;
 109
 110         default:
 111                 return -EINVAL;
 112         }
 113
 114         return 0;
 115 }
 116
 117 static void gta01_bat_ext_changed(struct power_supply *psy)
 118 {
 119         struct gta01_battery *bat = container_of(psy, struct gta01_battery, psy);
 120         power_supply_changed(&bat->psy);
 121 }
 122
 123 static int gta01_battery_probe(struct platform_device *pdev)
 124 {
 125         struct gta01_battery *gta01_bat;
 126
 127         gta01_bat = kzalloc(sizeof(*gta01_bat), GFP_KERNEL);
 128         if (!gta01_bat)
 129                 return -ENOMEM;
 130
 131         gta01_bat->psy.name = "battery";
 132         gta01_bat->psy.type = POWER_SUPPLY_TYPE_BATTERY;
 133         gta01_bat->psy.properties = gta01_bat_props;
 134         gta01_bat->psy.num_properties = ARRAY_SIZE(gta01_bat_props);
 135         gta01_bat->psy.get_property = gta01_bat_get_property;
 136         gta01_bat->psy.external_power_changed = gta01_bat_ext_changed;
 137
 138         gta01_bat->pdata = pdev->dev.platform_data;
 139         platform_set_drvdata(pdev, gta01_bat);
 140         power_supply_register(&pdev->dev, &gta01_bat->psy);
 141
 142         return 0;
 143 }
 144
 145 static int gta01_battery_remove(struct platform_device *pdev)
 146 {
 147         struct gta01_battery *bat = platform_get_drvdata(pdev);
 148
 149         power_supply_unregister(&bat->psy);
 150         kfree(bat);
 151
 152         return 0;
 153 }
 154
 155 static struct platform_driver gta01_battery_driver = {
 156         .driver = {
 157                 .name = "gta01_battery",
 158         },
 159         .probe    = gta01_battery_probe,
 160         .remove   = gta01_battery_remove,
 161 };
 162
 163 static int __init gta01_battery_init(void)
 164 {
 165         return platform_driver_register(&gta01_battery_driver);
 166 }
 167
 168 static void __exit gta01_battery_exit(void)
 169 {
 170         platform_driver_unregister(&gta01_battery_driver);
 171 }
 172
 173 module_init(gta01_battery_init);
 174 module_exit(gta01_battery_exit);
 175
 176 MODULE_LICENSE("GPL");
 177 MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
 178 MODULE_DESCRIPTION("gta01 battery driver");