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>

1 files changed, 47 insertions, 10 deletions

diff --git a/drivers/power/apm_power.c b/drivers/power/apm_power.c
index 32ebfd76722a..3928e7cdddc1 100644
--- 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)