[RFC PATCH v3 3/9] power: supply: Support DT originated temperature-capacity tables

[Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>]

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Support obtaining the "capacity degradation by temperature" - tables
from device-tree to batinfo.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>

---
RFCv3:
 - rename simple_gauge_temp_degr to power_supply_temp_degr
---
 drivers/power/supply/power_supply_core.c | 53 ++++++++++++++++++++++++
 include/linux/power_supply.h             | 26 ++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index 295672165836..1a21f692ab81 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -562,10 +562,12 @@ struct power_supply *devm_power_supply_get_by_phandle(struct device *dev,
 EXPORT_SYMBOL_GPL(devm_power_supply_get_by_phandle);
 #endif /* CONFIG_OF */
 
+#define POWER_SUPPLY_TEMP_DGRD_MAX_VALUES 100
 int power_supply_get_battery_info(struct power_supply *psy,
 				  struct power_supply_battery_info *info)
 {
 	struct power_supply_resistance_temp_table *resist_table;
+	u32 *dgrd_table;
 	struct device_node *battery_np;
 	const char *value;
 	int err, len, index;
@@ -588,6 +590,8 @@ int power_supply_get_battery_info(struct power_supply *psy,
 	info->temp_max                       = INT_MAX;
 	info->factory_internal_resistance_uohm  = -EINVAL;
 	info->resist_table = NULL;
+	info->temp_dgrd_values = 0;
+	info->temp_dgrd = NULL;
 
 	for (index = 0; index < POWER_SUPPLY_OCV_TEMP_MAX; index++) {
 		info->ocv_table[index]       = NULL;
@@ -677,6 +681,55 @@ int power_supply_get_battery_info(struct power_supply *psy,
 	of_property_read_u32_index(battery_np, "operating-range-celsius",
 				   1, &info->temp_max);
 
+	len = of_property_count_u32_elems(battery_np, "temp-degrade-table");
+	if (len == -EINVAL)
+		len = 0;
+	if (len < 0) {
+		err = len;
+		goto out_put_node;
+	}
+	/* table should consist of value pairs - maximum of 100 pairs */
+	if (len % 3 || len / 3 > POWER_SUPPLY_TEMP_DGRD_MAX_VALUES) {
+		dev_warn(&psy->dev,
+			 "bad amount of temperature-capacity degrade values\n");
+		err = -EINVAL;
+		goto out_put_node;
+	}
+	info->temp_dgrd_values = len / 3;
+	if (info->temp_dgrd_values) {
+		info->temp_dgrd = devm_kcalloc(&psy->dev,
+					       info->temp_dgrd_values,
+					       sizeof(*info->temp_dgrd),
+					       GFP_KERNEL);
+		if (!info->temp_dgrd) {
+			err = -ENOMEM;
+			goto out_put_node;
+		}
+		dgrd_table = kcalloc(len, sizeof(*dgrd_table), GFP_KERNEL);
+		if (!dgrd_table) {
+			err = -ENOMEM;
+			goto out_put_node;
+		}
+		err = of_property_read_u32_array(battery_np,
+						 "temp-degrade-table",
+						 dgrd_table, len);
+		if (err) {
+			dev_warn(&psy->dev,
+				 "bad temperature - capacity degrade values %d\n", err);
+			kfree(dgrd_table);
+			info->temp_dgrd_values = 0;
+			goto out_put_node;
+		}
+		for (index = 0; index < info->temp_dgrd_values; index++) {
+			struct power_supply_temp_degr *d = &info->temp_dgrd[index];
+
+			d->temp_degrade_1C = dgrd_table[index * 3];
+			d->degrade_at_set = dgrd_table[index * 3 + 1];
+			d->temp_set_point = dgrd_table[index * 3 + 2];
+		}
+		kfree(dgrd_table);
+	}
+
 	len = of_property_count_u32_elems(battery_np, "ocv-capacity-celsius");
 	if (len < 0 && len != -EINVAL) {
 		err = len;
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index fa8cf434f7e3..fbc07d403f41 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -214,6 +214,30 @@ union power_supply_propval {
 struct device_node;
 struct power_supply;
 
+/**
+ * struct power_supply_temp_degr - impact of temperature to battery capacity
+ *
+ * Usually temperature impacts on battery capacity. For systems where it is
+ * sufficient to describe capacity change as a series of temperature ranges
+ * where the change is linear (Eg delta cap = temperature_change * constant +
+ * offset) can be described by this structure.
+ *
+ * Please note - in order to avoid unnecessary rounding errors the change
+ * of capacity (uAh) is per change of temperature degree C while the temperature
+ * range floor is in tenths of degree C
+ *
+ * @temp_set_point:	Temperature where cap change is as given in
+ *			degrade_at_set. Units are 0.1 degree C
+ * @degrade_at_set:	Capacity difference (from ideal) at temp_set_point
+ *			temperature
+ * @temp_degrade_1C:	Capacity change / temperature change (uAh / degree C)
+ */
+struct power_supply_temp_degr {
+	int temp_set_point;
+	int degrade_at_set;
+	int temp_degrade_1C;
+};
+
 /* Run-time specific power supply configuration */
 struct power_supply_config {
 	struct device_node *of_node;
@@ -377,6 +401,8 @@ struct power_supply_battery_info {
 	int ocv_table_size[POWER_SUPPLY_OCV_TEMP_MAX];
 	struct power_supply_resistance_temp_table *resist_table;
 	int resist_table_size;
+	int temp_dgrd_values;
+	struct power_supply_temp_degr *temp_dgrd;
 };
 
 extern struct atomic_notifier_head power_supply_notifier;
-- 
2.31.1


-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =] 

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