Commit fa93854f authored by Ognjen Galic's avatar Ognjen Galic Committed by Rafael J. Wysocki
Browse files

battery: Add the battery hooking API 



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: default avatarOgnjen Galic <smclt30p@gmail.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 91ab883e

drivers/acpi/ac.c

+1 −1
Original line number Diff line number Diff line
@@ -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: "

drivers/acpi/battery.c

+144 −3
Original line number Diff line number Diff line
@@ -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: "
@@ -125,6 +129,7 @@ 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;
@@ -630,6 +635,139 @@ 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 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_entry(battery, &acpi_battery_list, 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);



/*

 * 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.

*/

static void battery_hook_add_battery(struct acpi_battery *battery)

{

	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, };
@@ -657,6 +795,7 @@ static int sysfs_add_battery(struct acpi_battery *battery) 
		battery->bat = NULL;

		return result;

	}

	battery_hook_add_battery(battery);

	return device_create_file(&battery->bat->dev, &alarm_attr);

}
@@ -667,7 +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;
@@ -1399,8 +1538,10 @@ 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);

drivers/acpi/sbs.c

+1 −1
Original line number Diff line number Diff line
@@ -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: "

drivers/acpi/battery.h→include/acpi/battery.h

+21 −0
Original line number Diff line number Diff line
@@ -8,4 +8,14 @@ 
#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

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