Add simple wrappers for accessing power supply's function attributes:
- get_property -> power_supply_get_property
- set_property -> power_supply_set_property
- property_is_writeable -> power_supply_property_is_writeable
- external_power_changed -> power_supply_external_power_changed
This API along with usage counter adds a safe way of accessing a power
supply from another driver. If power supply is unregistered after
obtaining reference to it by some driver, then the API wrappers won't be
executed in invalid (freed) context.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
---
drivers/power/power_supply_core.c | 47 ++++++++++++++++++++++++++++++++++++++-
include/linux/power_supply.h | 16 +++++++++++++
2 files changed, 62 insertions(+), 1 deletion(-)
diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
index b748391c3e17..fdec3c29fc3c 100644
--- a/drivers/power/power_supply_core.c
+++ b/drivers/power/power_supply_core.c
@@ -314,7 +314,8 @@ EXPORT_SYMBOL_GPL(power_supply_is_system_supplied);
int power_supply_set_battery_charged(struct power_supply *psy)
{
- if (psy->type == POWER_SUPPLY_TYPE_BATTERY && psy->set_charged) {
+ if (psy->use_cnt >= 0 && psy->type == POWER_SUPPLY_TYPE_BATTERY &&
+ psy->set_charged) {
psy->set_charged(psy);
return 0;
}
@@ -366,6 +367,47 @@ struct power_supply *power_supply_get_by_phandle(struct device_node *np,
EXPORT_SYMBOL_GPL(power_supply_get_by_phandle);
#endif /* CONFIG_OF */
+int power_supply_get_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ union power_supply_propval *val)
+{
+ if (psy->use_cnt <= 0)
+ return -ENODEV;
+
+ return psy->get_property(psy, psp, val);
+}
+EXPORT_SYMBOL_GPL(power_supply_get_property);
+
+int power_supply_set_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ const union power_supply_propval *val)
+{
+ if (psy->use_cnt <= 0 || !psy->set_property)
+ return -ENODEV;
+
+ return psy->set_property(psy, psp, val);
+}
+EXPORT_SYMBOL_GPL(power_supply_set_property);
+
+int power_supply_property_is_writeable(struct power_supply *psy,
+ enum power_supply_property psp)
+{
+ if (psy->use_cnt <= 0 || !psy->property_is_writeable)
+ return -ENODEV;
+
+ return psy->property_is_writeable(psy, psp);
+}
+EXPORT_SYMBOL_GPL(power_supply_property_is_writeable);
+
+void power_supply_external_power_changed(struct power_supply *psy)
+{
+ if (psy->use_cnt <= 0 || !psy->external_power_changed)
+ return;
+
+ psy->external_power_changed(psy);
+}
+EXPORT_SYMBOL_GPL(power_supply_external_power_changed);
+
int power_supply_powers(struct power_supply *psy, struct device *dev)
{
return sysfs_create_link(&psy->dev->kobj, &dev->kobj, "powers");
@@ -555,6 +597,7 @@ static int __power_supply_register(struct device *parent,
dev->release = power_supply_dev_release;
dev_set_drvdata(dev, psy);
psy->dev = dev;
+ psy->use_cnt++;
if (cfg) {
psy->drv_data = cfg->drv_data;
psy->of_node = cfg->of_node;
@@ -629,6 +672,8 @@ EXPORT_SYMBOL_GPL(power_supply_register_no_ws);
void power_supply_unregister(struct power_supply *psy)
{
+ psy->use_cnt--;
+ WARN_ON(psy->use_cnt);
cancel_work_sync(&psy->changed_work);
sysfs_remove_link(&psy->dev->kobj, "powers");
power_supply_remove_triggers(psy);
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index b203a26d5c54..c2c17ac3a608 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -199,6 +199,12 @@ struct power_supply {
size_t num_supplies;
struct device_node *of_node;
+ /*
+ * Functions for drivers implementing power supply class.
+ * These shouldn't be called directly by other drivers for accessing
+ * this power supply. Instead use power_supply_*() functions (for
+ * example power_supply_get_property()).
+ */
int (*get_property)(struct power_supply *psy,
enum power_supply_property psp,
union power_supply_propval *val);
@@ -227,6 +233,7 @@ struct power_supply {
struct work_struct changed_work;
spinlock_t changed_lock;
bool changed;
+ int use_cnt;
#ifdef CONFIG_THERMAL
struct thermal_zone_device *tzd;
struct thermal_cooling_device *tcd;
@@ -287,6 +294,15 @@ extern int power_supply_is_system_supplied(void);
static inline int power_supply_is_system_supplied(void) { return -ENOSYS; }
#endif
+extern int power_supply_get_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ union power_supply_propval *val);
+extern int power_supply_set_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ const union power_supply_propval *val);
+extern int power_supply_property_is_writeable(struct power_supply *psy,
+ enum power_supply_property psp);
+extern void power_supply_external_power_changed(struct power_supply *psy);
extern int power_supply_register(struct device *parent,
struct power_supply *psy,
const struct power_supply_config *cfg);
--
1.9.1
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