Re: [PATCH RFC v2 3/5] power: supply: core: implement extension API

From: Armin Wolf
Date: Thu Jun 13 2024 - 19:11:46 EST

Am 08.06.24 um 21:19 schrieb Thomas Weißschuh:

Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
drivers/power/supply/power_supply.h | 13 ++-
drivers/power/supply/power_supply_core.c | 128 ++++++++++++++++++++++++++++--
drivers/power/supply/power_supply_hwmon.c | 2 +-
drivers/power/supply/power_supply_sysfs.c | 37 ++++++++-
include/linux/power_supply.h | 26 ++++++
5 files changed, 192 insertions(+), 14 deletions(-)

diff --git a/drivers/power/supply/power_supply.h b/drivers/power/supply/power_supply.h
index 622be1f0a180..686b66161900 100644
--- a/drivers/power/supply/power_supply.h
+++ b/drivers/power/supply/power_supply.h
@@ -13,8 +13,17 @@ struct device;
struct device_type;
struct power_supply;

-extern bool power_supply_has_property(const struct power_supply_desc *psy_desc,
- enum power_supply_property psp);
+struct psy_ext_registration {
+ struct list_head list_head;
+ const struct power_supply_ext *ext;
+};
+
+#define psy_for_each_extension(psy, pos) list_for_each_entry(pos, &(psy)->extensions, list_head)

Hi,

sorry for taking so long to respond, the patch looks good to me except one single thing:

when removing a power supply extension, the driver has to be sure that no one is still using
the removed extension. So you might want to add some sort of locking when using a power supply
extension.

Thanks,
Armin Wolf

+
+bool power_supply_has_property(const struct power_supply *psy,
+ enum power_supply_property psp);
+bool power_supply_ext_has_property(const struct power_supply_ext *psy_ext,
+ enum power_supply_property psp);

#ifdef CONFIG_SYSFS

diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index d57ecdd966e0..fcdfedf3df7c 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -1183,8 +1183,8 @@ bool power_supply_battery_bti_in_range(struct power_supply_battery_info *info,
}
EXPORT_SYMBOL_GPL(power_supply_battery_bti_in_range);

-bool power_supply_has_property(const struct power_supply_desc *psy_desc,
- enum power_supply_property psp)
+static bool psy_desc_has_property(const struct power_supply_desc *psy_desc,
+ enum power_supply_property psp)
{
bool found = false;
int i;
@@ -1199,17 +1199,55 @@ bool power_supply_has_property(const struct power_supply_desc *psy_desc,
return found;
}

+bool power_supply_ext_has_property(const struct power_supply_ext *psy_ext,
+ enum power_supply_property psp)
+{
+ bool found = false;
+ int i;
+
+ if (!psy_ext)
+ return false;
+
+ for (i = 0; i < psy_ext->num_properties; i++) {
+ if (psy_ext->properties[i] == psp) {
+ found = true;
+ break;
+ }
+ }
+
+ return found;
+}
+
+bool power_supply_has_property(const struct power_supply *psy,
+ enum power_supply_property psp)
+{
+ struct psy_ext_registration *reg;
+
+ psy_for_each_extension(psy, reg)
+ if (power_supply_ext_has_property(reg->ext, psp))
+ return true;
+
+ return psy_desc_has_property(psy->desc, psp);
+}
+
int power_supply_get_property(struct power_supply *psy,
enum power_supply_property psp,
union power_supply_propval *val)
{
+ struct psy_ext_registration *reg;
+
if (atomic_read(&psy->use_cnt) <= 0) {
if (!psy->initialized)
return -EAGAIN;
return -ENODEV;
}

- if (power_supply_has_property(psy->desc, psp))
+ psy_for_each_extension(psy, reg) {
+ if (power_supply_ext_has_property(reg->ext, psp))
+ return reg->ext->get_property(psy, reg->ext, psp, val);
+ }
+
+ if (psy_desc_has_property(psy->desc, psp))
return psy->desc->get_property(psy, psp, val);
else if (power_supply_battery_info_has_prop(psy->battery_info, psp))
return power_supply_battery_info_get_prop(psy->battery_info, psp, val);
@@ -1222,7 +1260,21 @@ int power_supply_set_property(struct power_supply *psy,
enum power_supply_property psp,
const union power_supply_propval *val)
{
- if (atomic_read(&psy->use_cnt) <= 0 || !psy->desc->set_property)
+ struct psy_ext_registration *reg;
+
+ if (atomic_read(&psy->use_cnt) <= 0)
+ return -ENODEV;
+
+ psy_for_each_extension(psy, reg) {
+ if (power_supply_ext_has_property(reg->ext, psp)) {
+ if (reg->ext->set_property)
+ return reg->ext->set_property(psy, reg->ext, psp, val);
+ else
+ return -ENODEV;
+ }
+ }
+
+ if (!psy->desc->set_property)
return -ENODEV;

return psy->desc->set_property(psy, psp, val);
@@ -1232,8 +1284,21 @@ EXPORT_SYMBOL_GPL(power_supply_set_property);
int power_supply_property_is_writeable(struct power_supply *psy,
enum power_supply_property psp)
{
- if (atomic_read(&psy->use_cnt) <= 0 ||
- !psy->desc->property_is_writeable)
+ struct psy_ext_registration *reg;
+
+ if (atomic_read(&psy->use_cnt) <= 0)
+ return -ENODEV;
+
+ psy_for_each_extension(psy, reg) {
+ if (power_supply_ext_has_property(reg->ext, psp)) {
+ if (reg->ext->property_is_writeable)
+ return reg->ext->property_is_writeable(psy, reg->ext, psp);
+ else
+ return -ENODEV;
+ }
+ }
+
+ if (!psy->desc->property_is_writeable)
return -ENODEV;

return psy->desc->property_is_writeable(psy, psp);
@@ -1256,6 +1321,52 @@ int power_supply_powers(struct power_supply *psy, struct device *dev)
}
EXPORT_SYMBOL_GPL(power_supply_powers);

+static int power_supply_update_groups(struct power_supply *psy)
+{
+ int ret;
+
+ ret = sysfs_update_groups(&psy->dev.kobj, power_supply_dev_type.groups);
+ power_supply_changed(psy);
+ return ret;
+}
+
+int power_supply_register_extension(struct power_supply *psy, const struct power_supply_ext *ext)
+{
+ struct psy_ext_registration *reg;
+ size_t i;
+
+ for (i = 0; i < ext->num_properties; i++) {
+ if (power_supply_has_property(psy, ext->properties[i]))
+ return -EEXIST;
+ }
+
+ reg = devm_kmalloc(&psy->dev, sizeof(*reg), GFP_KERNEL);
+ if (!reg)
+ return -ENOMEM;
+
+ reg->ext = ext;
+ list_add(&reg->list_head, &psy->extensions);
+
+ return power_supply_update_groups(psy);
+}
+EXPORT_SYMBOL_GPL(power_supply_register_extension);
+
+void power_supply_unregister_extension(struct power_supply *psy, const struct power_supply_ext *ext)
+{
+ struct psy_ext_registration *reg;
+
+ psy_for_each_extension(psy, reg) {
+ if (reg->ext == ext) {
+ list_del(&reg->list_head);
+ power_supply_update_groups(psy);
+ return;
+ }
+ }
+
+ dev_warn(&psy->dev, "Trying to unregister invalid extension");
+}
+EXPORT_SYMBOL_GPL(power_supply_unregister_extension);
+
static void power_supply_dev_release(struct device *dev)
{
struct power_supply *psy = to_power_supply(dev);
@@ -1308,7 +1419,7 @@ static int psy_register_thermal(struct power_supply *psy)
return 0;

/* Register battery zone device psy reports temperature */
- if (power_supply_has_property(psy->desc, POWER_SUPPLY_PROP_TEMP)) {
+ if (power_supply_has_property(psy, POWER_SUPPLY_PROP_TEMP)) {
/* Prefer our hwmon device and avoid duplicates */
struct thermal_zone_params tzp = {
.no_hwmon = IS_ENABLED(CONFIG_POWER_SUPPLY_HWMON)
@@ -1361,7 +1472,7 @@ __power_supply_register(struct device *parent,
pr_warn("%s: Expected proper parent device for '%s'\n",
__func__, desc->name);

- if (power_supply_has_property(desc, POWER_SUPPLY_PROP_USB_TYPE) &&
+ if (psy_desc_has_property(desc, POWER_SUPPLY_PROP_USB_TYPE) &&
(!desc->usb_types || !desc->num_usb_types))
return ERR_PTR(-EINVAL);

@@ -1415,6 +1526,7 @@ __power_supply_register(struct device *parent,
}

spin_lock_init(&psy->changed_lock);
+ INIT_LIST_HEAD(&psy->extensions);
rc = device_add(dev);
if (rc)
goto device_add_failed;
diff --git a/drivers/power/supply/power_supply_hwmon.c b/drivers/power/supply/power_supply_hwmon.c
index 2ecbe4a74c25..8cb852a734b1 100644
--- a/drivers/power/supply/power_supply_hwmon.c
+++ b/drivers/power/supply/power_supply_hwmon.c
@@ -374,7 +374,7 @@ int power_supply_add_hwmon_sysfs(struct power_supply *psy)
for (i = 0; i < ARRAY_SIZE(power_supply_hwmon_props); i++) {
const enum power_supply_property prop = power_supply_hwmon_props[i];

- if (power_supply_has_property(psy->desc, prop))
+ if (power_supply_has_property(psy, prop))
set_bit(prop, psyhw->props);
}

diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
index abd44ebfe6fe..8f29ddea08d0 100644
--- a/drivers/power/supply/power_supply_sysfs.c
+++ b/drivers/power/supply/power_supply_sysfs.c
@@ -271,6 +271,23 @@ static ssize_t power_supply_show_usb_type(struct device *dev,
return count;
}

+static ssize_t power_supply_show_charge_behaviour(struct device *dev,
+ struct power_supply *psy,
+ union power_supply_propval *value,
+ char *buf)
+{
+ struct psy_ext_registration *reg;
+
+ psy_for_each_extension(psy, reg) {
+ if (power_supply_ext_has_property(reg->ext, POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR))
+ return power_supply_charge_behaviour_show(dev, reg->ext->charge_behaviours,
+ value->intval, buf);
+ }
+
+ return power_supply_charge_behaviour_show(dev, psy->desc->charge_behaviours,
+ value->intval, buf);
+}
+
static ssize_t power_supply_show_property(struct device *dev,
struct device_attribute *attr,
char *buf) {
@@ -304,8 +321,7 @@ static ssize_t power_supply_show_property(struct device *dev,
&value, buf);
break;
case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
- ret = power_supply_charge_behaviour_show(dev, psy->desc->charge_behaviours,
- value.intval, buf);
+ ret = power_supply_show_charge_behaviour(dev, psy, &value, buf);
break;
case POWER_SUPPLY_PROP_MODEL_NAME ... POWER_SUPPLY_PROP_SERIAL_NUMBER:
ret = sysfs_emit(buf, "%s\n", value.strval);
@@ -374,7 +390,7 @@ static umode_t power_supply_attr_is_visible(struct kobject *kobj,
if (attrno == POWER_SUPPLY_PROP_TYPE)
return mode;

- if (power_supply_has_property(psy->desc, attrno)) {
+ if (power_supply_has_property(psy, attrno)) {
if (power_supply_property_is_writeable(psy, attrno) > 0)
mode |= S_IWUSR;
return mode;
@@ -459,6 +475,7 @@ int power_supply_uevent(const struct device *dev, struct kobj_uevent_env *env)
power_supply_battery_info_properties;
unsigned long psy_drv_properties[POWER_SUPPLY_ATTR_CNT /
sizeof(unsigned long) + 1] = {0};
+ struct psy_ext_registration *ext;
int ret = 0, j;
char *prop_buf;

@@ -486,7 +503,21 @@ int power_supply_uevent(const struct device *dev, struct kobj_uevent_env *env)
if (ret)
goto out;

+ psy_for_each_extension(psy, ext) {
+ for (j = 0; j < ext->ext->num_properties; j++) {
+ if (test_bit(ext->ext->properties[j], psy_drv_properties))
+ continue;
+ set_bit(ext->ext->properties[j], psy_drv_properties);
+ ret = add_prop_uevent(dev, env, ext->ext->properties[j],
+ prop_buf);
+ if (ret)
+ goto out;
+ }
+ }
+
for (j = 0; j < psy->desc->num_properties; j++) {
+ if (test_bit(psy->desc->properties[j], psy_drv_properties))
+ continue;
set_bit(psy->desc->properties[j], psy_drv_properties);
ret = add_prop_uevent(dev, env, psy->desc->properties[j],
prop_buf);
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index 8e5705a56b85..128e7a67f268 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -15,6 +15,7 @@
#include <linux/device.h>
#include <linux/workqueue.h>
#include <linux/leds.h>
+#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/notifier.h>

@@ -280,6 +281,25 @@ struct power_supply_desc {
int use_for_apm;
};

+struct power_supply_ext {
+ u8 charge_behaviours;
+ const enum power_supply_property *properties;
+ size_t num_properties;
+
+ int (*get_property)(struct power_supply *psy,
+ const struct power_supply_ext *ext,
+ enum power_supply_property psp,
+ union power_supply_propval *val);
+ int (*set_property)(struct power_supply *psy,
+ const struct power_supply_ext *ext,
+ enum power_supply_property psp,
+ const union power_supply_propval *val);
+
+ int (*property_is_writeable)(struct power_supply *psy,
+ const struct power_supply_ext *ext,
+ enum power_supply_property psp);
+};
+
struct power_supply {
const struct power_supply_desc *desc;

@@ -303,6 +323,7 @@ struct power_supply {
bool removing;
atomic_t use_cnt;
struct power_supply_battery_info *battery_info;
+ struct list_head extensions;
#ifdef CONFIG_THERMAL
struct thermal_zone_device *tzd;
struct thermal_cooling_device *tcd;
@@ -892,6 +913,11 @@ devm_power_supply_register_no_ws(struct device *parent,
extern void power_supply_unregister(struct power_supply *psy);
extern int power_supply_powers(struct power_supply *psy, struct device *dev);

+extern int power_supply_register_extension(struct power_supply *psy,
+ const struct power_supply_ext *ext);
+extern void power_supply_unregister_extension(struct power_supply *psy,
+ const struct power_supply_ext *ext);
+
#define to_power_supply(device) container_of(device, struct power_supply, dev)

extern void *power_supply_get_drvdata(struct power_supply *psy);