apm_power: improve battery finding algorithm

Prior to this patch, if use_for_apm unspecified, apm_power able
to choice batteries according to their charge only.

This patch adds ability to choice batteries according to their charge,
energy, use_for_apm flag, and fallback to any battery if it failed to
decide.

Patch is mandatory to report Apple PMU batteries through legacy
/proc/apm interface using power supply class.

Signed-off-by: Anton Vorontsov <cbou@mail.ru>

diff --git a/drivers/power/apm_power.c b/drivers/power/apm_power.c
index 32ebfd7..3928e7c 100644 (file)
--- a/drivers/power/apm_power.c
+++ b/drivers/power/apm_power.c
@@ -26,28 +26,65 @@ static struct power_supply *main_battery;
 static void find_main_battery(void)
 {
        struct device *dev;
-       struct power_supply *bat, *batm;
+       struct power_supply *bat = NULL;
+       struct power_supply *max_charge_bat = NULL;
+       struct power_supply *max_energy_bat = NULL;
        union power_supply_propval full;
        int max_charge = 0;
+       int max_energy = 0;
 
        main_battery = NULL;
-       batm = NULL;
+
        list_for_each_entry(dev, &power_supply_class->devices, node) {
                bat = dev_get_drvdata(dev);
-               /* If none of battery devices cantains 'use_for_apm' flag,
-                  choice one with maximum design charge */
-               if (!PSY_PROP(bat, CHARGE_FULL_DESIGN, &full)) {
+
+               if (bat->use_for_apm) {
+                       /* nice, we explicitly asked to report this battery. */
+                       main_battery = bat;
+                       return;
+               }
+
+               if (!PSY_PROP(bat, CHARGE_FULL_DESIGN, &full) ||
+                               !PSY_PROP(bat, CHARGE_FULL, &full)) {
                        if (full.intval > max_charge) {
-                               batm = bat;
+                               max_charge_bat = bat;
                                max_charge = full.intval;
                        }
+               } else if (!PSY_PROP(bat, ENERGY_FULL_DESIGN, &full) ||
+                               !PSY_PROP(bat, ENERGY_FULL, &full)) {
+                       if (full.intval > max_energy) {
+                               max_energy_bat = bat;
+                               max_energy = full.intval;
+                       }
                }
+       }
 
-               if (bat->use_for_apm)
-                       main_battery = bat;
+       if ((max_energy_bat && max_charge_bat) &&
+                       (max_energy_bat != max_charge_bat)) {
+               /* try guess battery with more capacity */
+               if (!PSY_PROP(max_charge_bat, VOLTAGE_MAX_DESIGN, &full)) {
+                       if (max_energy > max_charge * full.intval)
+                               main_battery = max_energy_bat;
+                       else
+                               main_battery = max_charge_bat;
+               } else if (!PSY_PROP(max_energy_bat, VOLTAGE_MAX_DESIGN,
+                                                                 &full)) {
+                       if (max_charge > max_energy / full.intval)
+                               main_battery = max_charge_bat;
+                       else
+                               main_battery = max_energy_bat;
+               } else {
+                       /* give up, choice any */
+                       main_battery = max_energy_bat;
+               }
+       } else if (max_charge_bat) {
+               main_battery = max_charge_bat;
+       } else if (max_energy_bat) {
+               main_battery = max_energy_bat;
+       } else {
+               /* give up, try the last if any */
+               main_battery = bat;
        }
-       if (!main_battery)
-               main_battery = batm;
 }
 
 static int calculate_time(int status)