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Subject[PATCH v3 2/5] power: supply: core: Add battery internal resistance temperature table support
Date
From: Baolin Wang <baolin.wang@linaro.org>

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>
---
drivers/power/supply/power_supply_core.c | 67 +++++++++++++++++++++++++++++-
include/linux/power_supply.h | 10 +++++
2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index 5c36c43..1a9a9fa 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -565,9 +565,11 @@ struct power_supply *devm_power_supply_get_by_phandle(struct device *dev,
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
--- 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 @@ extern int power_supply_ocv2cap_simple(struct power_supply_battery_ocv_table *ta
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(
--
1.7.9.5
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