power: supply: core: Add battery internal resistance temperature table support

Since the battery internal resistance can be changed with the temperature
changes, thus add a resistance temperature table support to look up
the accurate battery internal resistance in a certain temperature.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index 5c36c43..1a9a9fa 100644 (file)
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -565,9 +565,11 @@ EXPORT_SYMBOL_GPL(devm_power_supply_get_by_phandle);
 int power_supply_get_battery_info(struct power_supply *psy,
                                  struct power_supply_battery_info *info)
 {
+       struct power_supply_resistance_temp_table *resist_table;
        struct device_node *battery_np;
        const char *value;
        int err, len, index;
+       const __be32 *list;
 
        info->energy_full_design_uwh         = -EINVAL;
        info->charge_full_design_uah         = -EINVAL;
@@ -578,6 +580,7 @@ int power_supply_get_battery_info(struct power_supply *psy,
        info->constant_charge_current_max_ua = -EINVAL;
        info->constant_charge_voltage_max_uv = -EINVAL;
        info->factory_internal_resistance_uohm  = -EINVAL;
+       info->resist_table = NULL;
 
        for (index = 0; index < POWER_SUPPLY_OCV_TEMP_MAX; index++) {
                info->ocv_table[index]       = NULL;
@@ -644,7 +647,6 @@ int power_supply_get_battery_info(struct power_supply *psy,
        for (index = 0; index < len; index++) {
                struct power_supply_battery_ocv_table *table;
                char *propname;
-               const __be32 *list;
                int i, tab_len, size;
 
                propname = kasprintf(GFP_KERNEL, "ocv-capacity-table-%d", index);
@@ -677,6 +679,26 @@ int power_supply_get_battery_info(struct power_supply *psy,
                }
        }
 
+       list = of_get_property(battery_np, "resistance-temp-table", &len);
+       if (!list || !len)
+               goto out_put_node;
+
+       info->resist_table_size = len / (2 * sizeof(__be32));
+       resist_table = info->resist_table = devm_kcalloc(&psy->dev,
+                                                        info->resist_table_size,
+                                                        sizeof(*resist_table),
+                                                        GFP_KERNEL);
+       if (!info->resist_table) {
+               power_supply_put_battery_info(psy, info);
+               err = -ENOMEM;
+               goto out_put_node;
+       }
+
+       for (index = 0; index < info->resist_table_size; index++) {
+               resist_table[index].temp = be32_to_cpu(*list++);
+               resist_table[index].resistance = be32_to_cpu(*list++);
+       }
+
 out_put_node:
        of_node_put(battery_np);
        return err;
@@ -692,10 +714,53 @@ void power_supply_put_battery_info(struct power_supply *psy,
                if (info->ocv_table[i])
                        devm_kfree(&psy->dev, info->ocv_table[i]);
        }
+
+       if (info->resist_table)
+               devm_kfree(&psy->dev, info->resist_table);
 }
 EXPORT_SYMBOL_GPL(power_supply_put_battery_info);
 
 /**
+ * power_supply_temp2resist_simple() - find the battery internal resistance
+ * percent
+ * @table: Pointer to battery resistance temperature table
+ * @table_len: The table length
+ * @ocv: Current temperature
+ *
+ * This helper function is used to look up battery internal resistance percent
+ * according to current temperature value from the resistance temperature table,
+ * and the table must be ordered descending. Then the actual battery internal
+ * resistance = the ideal battery internal resistance * percent / 100.
+ *
+ * Return: the battery internal resistance percent
+ */
+int power_supply_temp2resist_simple(struct power_supply_resistance_temp_table *table,
+                                   int table_len, int temp)
+{
+       int i, resist;
+
+       for (i = 0; i < table_len; i++)
+               if (temp > table[i].temp)
+                       break;
+
+       if (i > 0 && i < table_len) {
+               int tmp;
+
+               tmp = (table[i - 1].resistance - table[i].resistance) *
+                       (temp - table[i].temp);
+               tmp /= table[i - 1].temp - table[i].temp;
+               resist = tmp + table[i].resistance;
+       } else if (i == 0) {
+               resist = table[0].resistance;
+       } else {
+               resist = table[table_len - 1].resistance;
+       }
+
+       return resist;
+}
+EXPORT_SYMBOL_GPL(power_supply_temp2resist_simple);
+
+/**
  * power_supply_ocv2cap_simple() - find the battery capacity
  * @table: Pointer to battery OCV lookup table
  * @table_len: OCV table length

diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index 28413f7..dcd5a71 100644 (file)
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -325,6 +325,11 @@ struct power_supply_battery_ocv_table {
        int capacity;   /* percent */
 };
 
+struct power_supply_resistance_temp_table {
+       int temp;       /* celsius */
+       int resistance; /* internal resistance percent */
+};
+
 #define POWER_SUPPLY_OCV_TEMP_MAX 20
 
 /*
@@ -349,6 +354,8 @@ struct power_supply_battery_info {
        int ocv_temp[POWER_SUPPLY_OCV_TEMP_MAX];/* celsius */
        struct power_supply_battery_ocv_table *ocv_table[POWER_SUPPLY_OCV_TEMP_MAX];
        int ocv_table_size[POWER_SUPPLY_OCV_TEMP_MAX];
+       struct power_supply_resistance_temp_table *resist_table;
+       int resist_table_size;
 };
 
 extern struct atomic_notifier_head power_supply_notifier;
@@ -381,6 +388,9 @@ power_supply_find_ocv2cap_table(struct power_supply_battery_info *info,
                                int temp, int *table_len);
 extern int power_supply_batinfo_ocv2cap(struct power_supply_battery_info *info,
                                        int ocv, int temp);
+extern int
+power_supply_temp2resist_simple(struct power_supply_resistance_temp_table *table,
+                               int table_len, int temp);
 extern void power_supply_changed(struct power_supply *psy);
 extern int power_supply_am_i_supplied(struct power_supply *psy);
 extern int power_supply_set_input_current_limit_from_supplier(