[PATCH v2 2/4] power: supply: core: Introduce properties to present the battery OCV table

[Baolin Wang <baolin.wang@linaro.org>]

Some battery driver will use the open circuit voltage (OCV) value to look
up the corresponding battery capacity percent in one certain degree Celsius.
Thus this patch provides some battery properties to present the OCV table
temperatures and OCV capacity table values.

Suggested-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
Changes from v1:
 - New patch in v2.
---
 .../devicetree/bindings/power/supply/battery.txt   |   14 +++++
 drivers/power/supply/power_supply_core.c           |   63 +++++++++++++++++++-
 include/linux/power_supply.h                       |   11 ++++
 3 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/power/supply/battery.txt b/Documentation/devicetree/bindings/power/supply/battery.txt
index 25b9d2e..ac2b303 100644
--- a/Documentation/devicetree/bindings/power/supply/battery.txt
+++ b/Documentation/devicetree/bindings/power/supply/battery.txt
@@ -23,6 +23,16 @@ Optional Properties:
  - constant-charge-current-max-microamp: maximum constant input current
  - constant-charge-voltage-max-microvolt: maximum constant input voltage
  - internal-resistance-micro-ohms: battery internal resistance
+ - ocv-capacity-table-0: An array providing the battery capacity percent
+   with corresponding open circuit voltage (OCV) of the battery, which
+   is used to look up battery capacity according to current OCV value.
+ - ocv-capacity-table-1: Same as ocv-capacity-table-0
+ ......
+ - ocv-capacity-table-n: Same as ocv-capacity-table-0
+ - ocv-capacity-table-temperatures: An array containing the temperature
+   in degree Celsius, for each of the battery capacity lookup table.
+   The first temperature value specifies the OCV table 0, and the second
+   temperature value specifies the OCV table 1, and so on.
 
 Battery properties are named, where possible, for the corresponding
 elements in enum power_supply_property, defined in
@@ -44,6 +54,10 @@ Example:
 		constant-charge-current-max-microamp = <900000>;
 		constant-charge-voltage-max-microvolt = <4200000>;
 		internal-resistance-micro-ohms = <250000>;
+		ocv-capacity-table-temperatures = <(-10) 0 10>;
+		ocv-capacity-table-0 = <4185000 100>, <4113000 95>, <4066000 90>, ...;
+		ocv-capacity-table-1 = <4200000 100>, <4185000 95>, <4113000 90>, ...;
+		ocv-capacity-table-2 = <4250000 100>, <4200000 95>, <4185000 90>, ...;
 	};
 
 	charger: charger@11 {
diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index 9f3452f..151ff03 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -570,7 +570,7 @@ int power_supply_get_battery_info(struct power_supply *psy,
 {
 	struct device_node *battery_np;
 	const char *value;
-	int err;
+	int err, len, index;
 
 	info->energy_full_design_uwh         = -EINVAL;
 	info->charge_full_design_uah         = -EINVAL;
@@ -581,6 +581,12 @@ int power_supply_get_battery_info(struct power_supply *psy,
 	info->constant_charge_voltage_max_uv = -EINVAL;
 	info->internal_resistance_uohm       = -EINVAL;
 
+	for (index = 0; index < POWER_SUPPLY_OCV_TEMP_MAX; index++) {
+		info->ocv_table[index]       = NULL;
+		info->ocv_temp[index]        = -EINVAL;
+		info->ocv_table_size[index]  = -EINVAL;
+	}
+
 	if (!psy->of_node) {
 		dev_warn(&psy->dev, "%s currently only supports devicetree\n",
 			 __func__);
@@ -620,10 +626,65 @@ int power_supply_get_battery_info(struct power_supply *psy,
 	of_property_read_u32(battery_np, "internal-resistance-micro-ohms",
 			     &info->internal_resistance_uohm);
 
+	len = of_property_count_u32_elems(battery_np,
+					  "ocv-capacity-table-temperatures");
+	if (len < 0 && len != -EINVAL) {
+		return len;
+	} else if (len > POWER_SUPPLY_OCV_TEMP_MAX) {
+		dev_err(&psy->dev, "Too many temperature values\n");
+		return -EINVAL;
+	} else if (len > 0) {
+		of_property_read_u32_array(battery_np,
+					   "ocv-capacity-table-temperatures",
+					   info->ocv_temp, len);
+	}
+
+	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);
+		list = of_get_property(battery_np, propname, &size);
+		kfree(propname);
+		if (!list || !size) {
+			dev_err(&psy->dev, "failed to get ocv capacity table\n");
+			power_supply_put_battery_info(psy, info);
+			return -EINVAL;
+		}
+
+		tab_len = size / sizeof(*table);
+		info->ocv_table_size[index] = tab_len;
+
+		table = info->ocv_table[index] = devm_kzalloc(&psy->dev,
+						tab_len * sizeof(*table),
+						GFP_KERNEL);
+		if (!info->ocv_table[index]) {
+			power_supply_put_battery_info(psy, info);
+			return -ENOMEM;
+		}
+
+		for (i = 0; i < tab_len; i++) {
+			table[i].ocv = be32_to_cpu(*list++);
+			table[i].capacity = be32_to_cpu(*list++);
+		}
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(power_supply_get_battery_info);
 
+void power_supply_put_battery_info(struct power_supply *psy,
+				   struct power_supply_battery_info *info)
+{
+	int i;
+
+	for (i = 0; i < POWER_SUPPLY_OCV_TEMP_MAX; i++)
+		kfree(info->ocv_table[i]);
+}
+EXPORT_SYMBOL_GPL(power_supply_put_battery_info);
+
 int power_supply_get_property(struct power_supply *psy,
 			    enum power_supply_property psp,
 			    union power_supply_propval *val)
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index 019452d..b0a2768 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -309,6 +309,12 @@ struct power_supply_info {
 	int use_for_apm;
 };
 
+struct power_supply_battery_ocv_table {
+	int ocv;	/* microVolts */
+	int capacity;	/* percent */
+};
+
+#define POWER_SUPPLY_OCV_TEMP_MAX 20
 /*
  * This is the recommended struct to manage static battery parameters,
  * populated by power_supply_get_battery_info(). Most platform drivers should
@@ -327,6 +333,9 @@ struct power_supply_battery_info {
 	int constant_charge_current_max_ua; /* microAmps */
 	int constant_charge_voltage_max_uv; /* microVolts */
 	int internal_resistance_uohm;       /* microOhms */
+	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];
 };
 
 extern struct atomic_notifier_head power_supply_notifier;
@@ -350,6 +359,8 @@ extern struct power_supply *devm_power_supply_get_by_phandle(
 
 extern int power_supply_get_battery_info(struct power_supply *psy,
 					 struct power_supply_battery_info *info);
+extern void power_supply_put_battery_info(struct power_supply *psy,
+					  struct power_supply_battery_info *info);
 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