1/* -*- linux-c -*-
2 *
3 *	$Id: sysrq.h,v 1.1.1.1 2008/10/15 03:29:28 james26_jang Exp $
4 *
5 *	Linux Magic System Request Key Hacks
6 *
7 *	(c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
8 *
9 *	(c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
10 *	overhauled to use key registration
11 *	based upon discusions in irc://irc.openprojects.net/#kernelnewbies
12 */
13#ifndef __LINUX_SYSRQ_H__
14#define __LINUX_SYSRQ_H__
15
16#include <linux/config.h>
17
18struct pt_regs;
19struct kbd_struct;
20struct tty_struct;
21
22struct sysrq_key_op {
23	void (*handler)(int, struct pt_regs *,
24			struct kbd_struct *, struct tty_struct *);
25	char *help_msg;
26	char *action_msg;
27};
28
29#ifdef CONFIG_MAGIC_SYSRQ
30
31/* Generic SysRq interface -- you may call it from any device driver, supplying
32 * ASCII code of the key, pointer to registers and kbd/tty structs (if they
33 * are available -- else NULL's).
34 */
35
36void handle_sysrq(int, struct pt_regs *,
37		struct kbd_struct *, struct tty_struct *);
38
39
40/*
41 * Nonlocking version of handle sysrq, used by sysrq handlers that need to
42 * call sysrq handlers
43 */
44
45void __handle_sysrq_nolock(int, struct pt_regs *,
46                struct kbd_struct *, struct tty_struct *);
47
48
49
50/*
51 * Sysrq registration manipulation functions
52 */
53
54void __sysrq_lock_table (void);
55void __sysrq_unlock_table (void);
56struct sysrq_key_op *__sysrq_get_key_op (int key);
57void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p);
58
59extern __inline__ int
60__sysrq_swap_key_ops_nolock(int key, struct sysrq_key_op *insert_op_p,
61				struct sysrq_key_op *remove_op_p)
62{
63	int retval;
64	if (__sysrq_get_key_op(key) == remove_op_p) {
65		__sysrq_put_key_op(key, insert_op_p);
66		retval = 0;
67	} else {
68                retval = -1;
69	}
70	return retval;
71}
72
73extern __inline__ int
74__sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
75				struct sysrq_key_op *remove_op_p) {
76	int retval;
77	__sysrq_lock_table();
78	retval = __sysrq_swap_key_ops_nolock(key, insert_op_p, remove_op_p);
79	__sysrq_unlock_table();
80	return retval;
81}
82
83static inline int register_sysrq_key(int key, struct sysrq_key_op *op_p)
84{
85	return __sysrq_swap_key_ops(key, op_p, NULL);
86}
87
88static inline int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
89{
90	return __sysrq_swap_key_ops(key, NULL, op_p);
91}
92
93#else
94
95static inline int __reterr(void)
96{
97	return -EINVAL;
98}
99
100#define register_sysrq_key(ig,nore) __reterr()
101#define unregister_sysrq_key(ig,nore) __reterr()
102
103#endif
104
105
106/* Deferred actions */
107
108extern volatile int emergency_sync_scheduled;
109
110#define EMERG_SYNC 1
111#define EMERG_REMOUNT 2
112
113void do_emergency_sync(void);
114
115#ifdef CONFIG_MAGIC_SYSRQ
116#define CHECK_EMERGENCY_SYNC			\
117	if (emergency_sync_scheduled)		\
118		do_emergency_sync();
119#else
120#define CHECK_EMERGENCY_SYNC
121#endif
122
123#endif /* __LINUX_SYSRQ_H__ */
124