This is a patch that implements a generic hooking API for the
generic ACPI battery driver.
With this new generic API, drivers can expose platform specific
behaviour via sysfs attributes in /sys/class/power_supply/BATn/
in a generic way.
A perfect example of the need for this API are Lenovo ThinkPads.
Lenovo ThinkPads have a ACPI extension that allows the setting of
start and stop charge thresholds in the EC and battery firmware
via ACPI. The thinkpad_acpi module can use this API to expose
sysfs attributes that it controls inside the ACPI battery driver
sysfs tree, under /sys/class/power_supply/BATN/.
The file drivers/acpi/battery.h has been moved to
include/acpi/battery.h and the includes inside ac.c, sbs.c, and
battery.c have been adjusted to reflect that.
When drivers hooks into the API, the API calls add_battery() for
each battery in the system that passes it a acpi_battery
struct. Then, the drivers can use device_create_file() to create
new sysfs attributes with that struct and identify the batteries
for per-battery attributes.
Signed-off-by: Ognjen Galic <smclt30p@xxxxxxxxx>
---
Notes:
v7:
* Implemented mutual exclusion for hooking methods and battery
callbacks
* Fixed a BUG where errors in other modules would occur when the
modules that depend on battery get unloaded
v8:
* Use list_for_each_safe instead of list_for_each for the module
exit function where deletion of nodes occurs
v9:
* No changes in this patch in v9
v10:
* Fix compiler warnings in Intel's 0-day CI
v11:
* Fix changelog formatting
* Make lists and mutex static
v12:
* Change all applicable list_for_each to list_for_each_entry
* Define pr_fmt to include module name for pr_*
drivers/acpi/ac.c | 2 +-
drivers/acpi/battery.c | 151 ++++++++++++++++++++++++++++++++++++++++++++++++-
drivers/acpi/battery.h | 11 ----
drivers/acpi/sbs.c | 2 +-
include/acpi/battery.h | 21 +++++++
5 files changed, 171 insertions(+), 16 deletions(-)
delete mode 100644 drivers/acpi/battery.h
create mode 100644 include/acpi/battery.h
diff --git a/drivers/acpi/ac.c b/drivers/acpi/ac.c
index 47a7ed5..2d8de2f 100644
--- a/drivers/acpi/ac.c
+++ b/drivers/acpi/ac.c
@@ -33,7 +33,7 @@
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include <linux/acpi.h>
-#include "battery.h"
+#include <acpi/battery.h>
#define PREFIX "ACPI: "
diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 13e7b56..7089e31 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -21,8 +21,12 @@
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
#include <linux/kernel.h>
+#include <linux/list.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/jiffies.h>
@@ -42,7 +46,7 @@
#include <linux/acpi.h>
#include <linux/power_supply.h>
-#include "battery.h"
+#include <acpi/battery.h>
#define PREFIX "ACPI: "
@@ -124,6 +128,7 @@ struct acpi_battery {
struct power_supply_desc bat_desc;
struct acpi_device *device;
struct notifier_block pm_nb;
+ struct list_head list;
unsigned long update_time;
int revision;
int rate_now;
@@ -626,6 +631,142 @@ static const struct device_attribute alarm_attr = {
.store = acpi_battery_alarm_store,
};
+/*
+ * The Battery Hooking API
+ *
+ * This API is used inside other drivers that need to expose
+ * platform-specific behaviour within the generic driver in a
+ * generic way.
+ *
+ */
+
+static LIST_HEAD(acpi_battery_list);
+static LIST_HEAD(battery_hook_list);
+static DEFINE_MUTEX(hook_mutex);
+
+void __battery_hook_unregister(struct acpi_battery_hook *hook, int lock)
+{
+ struct list_head *position;
+ struct acpi_battery *battery;
+ /*
+ * In order to remove a hook, we first need to
+ * de-register all the batteries that are registered.
+ */
+ if (lock)
+ mutex_lock(&hook_mutex);
+ list_for_each(position, &acpi_battery_list) {
+ battery = list_entry(position, struct acpi_battery, list);
+ hook->remove_battery(battery->bat);
+ }
+ list_del(&hook->list);
+ if (lock)
+ mutex_unlock(&hook_mutex);
+ pr_info("extension unregistered: %s\n", hook->name);
+}
+
+void battery_hook_unregister(struct acpi_battery_hook *hook)
+{
+ __battery_hook_unregister(hook, 1);
+}
+EXPORT_SYMBOL_GPL(battery_hook_unregister);
+
+void battery_hook_register(struct acpi_battery_hook *hook)
+{
+ struct acpi_battery *battery;
+
+ mutex_lock(&hook_mutex);
+ INIT_LIST_HEAD(&hook->list);
+ list_add(&hook->list, &battery_hook_list);
+ /*
+ * Now that the driver is registered, we need
+ * to notify the hook that a battery is available
+ * for each battery, so that the driver may add
+ * its attributes.
+ */
+ list_for_each_entry(battery, &acpi_battery_list, list) {
+ if (hook->add_battery(battery->bat)) {
+ /*
+ * If a add-battery returns non-zero,
+ * the registration of the extension has failed,
+ * and we will not add it to the list of loaded
+ * hooks.
+ */
+ pr_err("extension failed to load: %s",
+ hook->name);
+ __battery_hook_unregister(hook, 0);
+ return;
+ }
+ }
+ pr_info("new extension: %s\n", hook->name);
+ mutex_unlock(&hook_mutex);
+}
+EXPORT_SYMBOL_GPL(battery_hook_register);
+
+static void battery_hook_add_battery(struct acpi_battery *battery)
+{
+ /*
+ * This function gets called right after the battery sysfs
+ * attributes have been added, so that the drivers that
+ * define custom sysfs attributes can add their own.
+ */
+ struct acpi_battery_hook *hook_node;
+
+ mutex_lock(&hook_mutex);
+ INIT_LIST_HEAD(&battery->list);
+ list_add(&battery->list, &acpi_battery_list);
+ /*
+ * Since we added a new battery to the list, we need to
+ * iterate over the hooks and call add_battery for each
+ * hook that was registered. This usually happens
+ * when a battery gets hotplugged or initialized
+ * during the battery module initialization.
+ */
+ list_for_each_entry(hook_node, &battery_hook_list, list) {
+ if (hook_node->add_battery(battery->bat)) {
+ /*
+ * The notification of the extensions has failed, to
+ * prevent further errors we will unload the extension.
+ */
+ __battery_hook_unregister(hook_node, 0);
+ pr_err("error in extension, unloading: %s",
+ hook_node->name);
+ }
+ }
+ mutex_unlock(&hook_mutex);
+}
+
+static void battery_hook_remove_battery(struct acpi_battery *battery)
+{
+ struct acpi_battery_hook *hook;
+
+ mutex_lock(&hook_mutex);
+ /*
+ * Before removing the hook, we need to remove all
+ * custom attributes from the battery.
+ */
+ list_for_each_entry(hook, &battery_hook_list, list) {
+ hook->remove_battery(battery->bat);
+ }
+ /* Then, just remove the battery from the list */
+ list_del(&battery->list);
+ mutex_unlock(&hook_mutex);
+}
+
+static void __exit battery_hook_exit(void)
+{
+ struct acpi_battery_hook *hook;
+ struct acpi_battery_hook *ptr;
+ /*
+ * At this point, the acpi_bus_unregister_driver
+ * has called remove for all batteries. We just
+ * need to remove the hooks.
+ */
+ list_for_each_entry_safe(hook, ptr, &battery_hook_list, list) {
+ __battery_hook_unregister(hook, 1);
+ }
+ mutex_destroy(&hook_mutex);
+}
+
static int sysfs_add_battery(struct acpi_battery *battery)
{
struct power_supply_config psy_cfg = { .drv_data = battery, };
@@ -647,6 +788,8 @@ static int sysfs_add_battery(struct acpi_battery *battery)
battery->bat = power_supply_register_no_ws(&battery->device->dev,
&battery->bat_desc, &psy_cfg);
+ battery_hook_add_battery(battery);
+
if (IS_ERR(battery->bat)) {
int result = PTR_ERR(battery->bat);
@@ -663,7 +806,7 @@ static void sysfs_remove_battery(struct acpi_battery *battery)
mutex_unlock(&battery->sysfs_lock);
return;
}
-
+ battery_hook_remove_battery(battery);
device_remove_file(&battery->bat->dev, &alarm_attr);
power_supply_unregister(battery->bat);
battery->bat = NULL;
@@ -1359,8 +1502,10 @@ static int __init acpi_battery_init(void)
static void __exit acpi_battery_exit(void)
{
async_synchronize_cookie(async_cookie + 1);
- if (battery_driver_registered)
+ if (battery_driver_registered) {
acpi_bus_unregister_driver(&acpi_battery_driver);
+ battery_hook_exit();
+ }
#ifdef CONFIG_ACPI_PROCFS_POWER
if (acpi_battery_dir)
acpi_unlock_battery_dir(acpi_battery_dir);
diff --git a/drivers/acpi/battery.h b/drivers/acpi/battery.h
deleted file mode 100644
index 225f493..0000000
--- a/drivers/acpi/battery.h
+++ /dev/null
@@ -1,11 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __ACPI_BATTERY_H
-#define __ACPI_BATTERY_H
-
-#define ACPI_BATTERY_CLASS "battery"
-
-#define ACPI_BATTERY_NOTIFY_STATUS 0x80
-#define ACPI_BATTERY_NOTIFY_INFO 0x81
-#define ACPI_BATTERY_NOTIFY_THRESHOLD 0x82
-
-#endif
diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
index a2428e9..295b592 100644
--- a/drivers/acpi/sbs.c
+++ b/drivers/acpi/sbs.c
@@ -32,9 +32,9 @@
#include <linux/delay.h>
#include <linux/power_supply.h>
#include <linux/platform_data/x86/apple.h>
+#include <acpi/battery.h>
#include "sbshc.h"
-#include "battery.h"
#define PREFIX "ACPI: "
diff --git a/include/acpi/battery.h b/include/acpi/battery.h
new file mode 100644
index 0000000..5d8f5d9
--- /dev/null
+++ b/include/acpi/battery.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ACPI_BATTERY_H
+#define __ACPI_BATTERY_H
+
+#define ACPI_BATTERY_CLASS "battery"
+
+#define ACPI_BATTERY_NOTIFY_STATUS 0x80
+#define ACPI_BATTERY_NOTIFY_INFO 0x81
+#define ACPI_BATTERY_NOTIFY_THRESHOLD 0x82
+
+struct acpi_battery_hook {
+ const char *name;
+ int (*add_battery)(struct power_supply *battery);
+ int (*remove_battery)(struct power_supply *battery);
+ struct list_head list;
+};
+
+void battery_hook_register(struct acpi_battery_hook *hook);
+void battery_hook_unregister(struct acpi_battery_hook *hook);
+
+#endif
--
2.7.4
