[PATCH v11 04/10] power: power_supply: Add power_supply_battery_info and API

Liam Breck
2017-03-20T09:52:45Z

From: Liam Breck <kernel@networkimprov.net>

power_supply_get_battery_info() reads battery data from devicetree.
struct power_supply_battery_info provides battery data to drivers.
Drivers may surface battery data in sysfs via corresponding
POWER_SUPPLY_PROP_* fields.

Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Liam Breck <kernel@networkimprov.net>
---
Documentation/power/power_supply_class.txt | 12 ++++++++
drivers/power/supply/power_supply_core.c | 45 ++++++++++++++++++++++++++++++
include/linux/power_supply.h | 18 ++++++++++++
3 files changed, 75 insertions(+)

diff --git a/Documentation/power/power_supply_class.txt b/Documentation/power/power_supply_class.txt
index 0c72588..dc92c77 100644
--- a/Documentation/power/power_supply_class.txt
+++ b/Documentation/power/power_supply_class.txt
@@ -174,6 +174,18 @@ issued by external power supply will notify supplicants via
external_power_changed callback.

+Devicetree battery characteristics
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Drivers should call power_supply_get_battery_info() to obtain battery
+characteristics from a devicetree battery node, defined in
+Documentation/devicetree/bindings/power/supply/battery.txt. This is
+implemented in drivers/power/supply/bq27xxx_battery.c.
+
+Properties in struct power_supply_battery_info and their counterparts in the
+battery node have names corresponding to elements in enum power_supply_property,
+for naming consistency between sysfs attributes and battery node properties.
+
+
QA
~~
Q: Where is POWER_SUPPLY_PROP_XYZ attribute?
diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index a74d8ca..61e20b1 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -17,6 +17,7 @@
#include <linux/device.h>
#include <linux/notifier.h>
#include <linux/err.h>
+#include <linux/of.h>
#include <linux/power_supply.h>
#include <linux/thermal.h>
#include "power_supply.h"
@@ -487,6 +488,50 @@ struct power_supply *devm_power_supply_get_by_phandle(struct device *dev,
EXPORT_SYMBOL_GPL(devm_power_supply_get_by_phandle);
#endif /* CONFIG_OF */

+int power_supply_get_battery_info(struct power_supply *psy,
+ struct power_supply_battery_info *info)
+{
+ struct device_node *battery_np;
+ const char *value;
+ int err;
+
+ info->energy_full_design_uwh = -EINVAL;
+ info->charge_full_design_uah = -EINVAL;
+ info->voltage_min_design_uv = -EINVAL;
+
+ if (!psy->of_node) {
+ dev_warn(&psy->dev, "%s currently only supports devicetree\n",
+ __func__);
+ return -ENXIO;
+ }
+
+ battery_np = of_parse_phandle(psy->of_node, "monitored-battery", 0);
+ if (!battery_np)
+ return -ENODEV;
+
+ err = of_property_read_string(battery_np, "compatible", &value);
+ if (err)
+ return err;
+
+ if (strcmp("simple-battery", value))
+ return -ENODEV;
+
+ /* The property and field names below must correspond to elements
+ * in enum power_supply_property. For reasoning, see
+ * Documentation/power/power_supply_class.txt.
+ */
+
+ of_property_read_u32(battery_np, "energy-full-design-microwatt-hours",
+ &info->energy_full_design_uwh);
+ of_property_read_u32(battery_np, "charge-full-design-microamp-hours",
+ &info->charge_full_design_uah);
+ of_property_read_u32(battery_np, "voltage-min-design-microvolt",
+ &info->voltage_min_design_uv);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(power_supply_get_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 3965503..e84f1d3 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -288,6 +288,21 @@ struct power_supply_info {
int use_for_apm;
};

+/*
+ * This is the recommended struct to manage static battery parameters,
+ * populated by power_supply_get_battery_info(). Most platform drivers should
+ * use these for consistency.
+ * Its field names must correspond to elements in enum power_supply_property.
+ * The default field value is -EINVAL.
+ * Power supply class itself doesn't use this.
+ */
+
+struct power_supply_battery_info {
+ int energy_full_design_uwh; /* microWatt-hours */
+ int charge_full_design_uah; /* microAmp-hours */
+ int voltage_min_design_uv; /* microVolts */
+};
+
extern struct atomic_notifier_head power_supply_notifier;
extern int power_supply_reg_notifier(struct notifier_block *nb);
extern void power_supply_unreg_notifier(struct notifier_block *nb);
@@ -306,6 +321,9 @@ static inline struct power_supply *
devm_power_supply_get_by_phandle(struct device *dev, const char *property)
{ return NULL; }
#endif /* CONFIG_OF */
+
+extern int power_supply_get_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_battery_charged(struct power_supply *psy);
--
2.9.3