include/linux/sysrq.h

   1 /* -*- linux-c -*-
   2  *
   3  *      $Id: sysrq.h,v 1.3 1997/07/17 11:54:33 mj 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
  14 #include <linux/config.h>
  15
  16 struct pt_regs;
  17 struct tty_struct;
  18
  19 struct sysrq_key_op {
  20         void (*handler)(int, struct pt_regs *, struct tty_struct *);
  21         char *help_msg;
  22         char *action_msg;
  23 };
  24
  25 #ifdef CONFIG_MAGIC_SYSRQ
  26
  27 /* Generic SysRq interface -- you may call it from any device driver, supplying
  28  * ASCII code of the key, pointer to registers and kbd/tty structs (if they
  29  * are available -- else NULL's).
  30  */
  31
  32 void handle_sysrq(int, struct pt_regs *, struct tty_struct *);
  33 void __handle_sysrq(int, struct pt_regs *, struct tty_struct *);
  34
  35 /*
  36  * Sysrq registration manipulation functions
  37  */
  38
  39 void __sysrq_lock_table (void);
  40 void __sysrq_unlock_table (void);
  41 struct sysrq_key_op *__sysrq_get_key_op (int key);
  42 void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p);
  43
  44 extern __inline__ int
  45 __sysrq_swap_key_ops_nolock(int key, struct sysrq_key_op *insert_op_p,
  46                                 struct sysrq_key_op *remove_op_p)
  47 {
  48         int retval;
  49         if (__sysrq_get_key_op(key) == remove_op_p) {
  50                 __sysrq_put_key_op(key, insert_op_p);
  51                 retval = 0;
  52         } else {
  53                 retval = -1;
  54         }
  55         return retval;
  56 }
  57
  58 extern __inline__ int
  59 __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
  60                                 struct sysrq_key_op *remove_op_p) {
  61         int retval;
  62         __sysrq_lock_table();
  63         retval = __sysrq_swap_key_ops_nolock(key, insert_op_p, remove_op_p);
  64         __sysrq_unlock_table();
  65         return retval;
  66 }
  67
  68 static inline int register_sysrq_key(int key, struct sysrq_key_op *op_p)
  69 {
  70         return __sysrq_swap_key_ops(key, op_p, NULL);
  71 }
  72
  73 static inline int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
  74 {
  75         return __sysrq_swap_key_ops(key, NULL, op_p);
  76 }
  77
  78 #else
  79
  80 static inline int __reterr(void)
  81 {
  82         return -EINVAL;
  83 }
  84
  85 #define register_sysrq_key(ig,nore) __reterr()
  86 #define unregister_sysrq_key(ig,nore) __reterr()
  87
  88 #endif