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kernel/reboot: Introduce sys-off handler API

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In order to support power-off chaining we need to get rid of the global
pm_* variables, replacing them with the new kernel API functions that
support chaining.

Introduce new generic sys-off handler API that brings the following
features:

1. Power-off and restart handlers are registered using same API function
   that supports chaining, hence all power-off and restart modes will
   support chaining using this unified function.

2. Prevents notifier priority collisions by disallowing registration of
   multiple handlers at the non-default priority level.

3. Supports passing opaque user argument to callback, which allows us to
   remove global variables from drivers.

This patch adds support of the following sys-off modes:

- SYS_OFF_MODE_POWER_OFF_PREPARE that replaces global pm_power_off_prepare
  variable and provides chaining support for power-off-prepare handlers.

- SYS_OFF_MODE_POWER_OFF that replaces global pm_power_off variable and
  provides chaining support for power-off handlers.

- SYS_OFF_MODE_RESTART that provides a better restart API, removing a need
  from drivers to have a global scratch variable by utilizing the opaque
  callback argument.

Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Dmitry Osipenko
2022-05-10 02:32:11 +03:00
committed by Rafael J. Wysocki
parent c82f898d87
commit 232edc2f72
2 changed files with 259 additions and 0 deletions
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77
include/linux/reboot.h
View File

@@ -7,6 +7,7 @@
#include <uapi/linux/reboot.h>
struct device;
struct sys_off_handler;
#define SYS_DOWN 0x0001 /* Notify of system down */
#define SYS_RESTART SYS_DOWN
@@ -62,6 +63,82 @@ extern void machine_shutdown(void);
struct pt_regs;
extern void machine_crash_shutdown(struct pt_regs *);
/*
* sys-off handler API.
*/
/*
* Standard sys-off priority levels. Users are expected to set priorities
* relative to the standard levels.
*
* SYS_OFF_PRIO_PLATFORM: Use this for platform-level handlers.
*
* SYS_OFF_PRIO_LOW: Use this for handler of last resort.
*
* SYS_OFF_PRIO_DEFAULT: Use this for normal handlers.
*
* SYS_OFF_PRIO_HIGH: Use this for higher priority handlers.
*
* SYS_OFF_PRIO_FIRMWARE: Use this if handler uses firmware call.
*/
#define SYS_OFF_PRIO_PLATFORM -256
#define SYS_OFF_PRIO_LOW -128
#define SYS_OFF_PRIO_DEFAULT 0
#define SYS_OFF_PRIO_HIGH 192
#define SYS_OFF_PRIO_FIRMWARE 224
enum sys_off_mode {
/**
* @SYS_OFF_MODE_POWER_OFF_PREPARE:
*
* Handlers prepare system to be powered off. Handlers are
* allowed to sleep.
*/
SYS_OFF_MODE_POWER_OFF_PREPARE,
/**
* @SYS_OFF_MODE_POWER_OFF:
*
* Handlers power-off system. Handlers are disallowed to sleep.
*/
SYS_OFF_MODE_POWER_OFF,
/**
* @SYS_OFF_MODE_RESTART:
*
* Handlers restart system. Handlers are disallowed to sleep.
*/
SYS_OFF_MODE_RESTART,
};
/**
* struct sys_off_data - sys-off callback argument
*
* @mode: Mode ID. Currently used only by the sys-off restart mode,
* see enum reboot_mode for the available modes.
* @cb_data: User's callback data.
* @cmd: Command string. Currently used only by the sys-off restart mode,
* NULL otherwise.
*/
struct sys_off_data {
int mode;
void *cb_data;
const char *cmd;
};
struct sys_off_handler *
register_sys_off_handler(enum sys_off_mode mode,
int priority,
int (*callback)(struct sys_off_data *data),
void *cb_data);
void unregister_sys_off_handler(struct sys_off_handler *handler);
int devm_register_sys_off_handler(struct device *dev,
enum sys_off_mode mode,
int priority,
int (*callback)(struct sys_off_data *data),
void *cb_data);
/*
* Architecture independent implemenations of sys_reboot commands.
*/