media: ov5640: Add Omnivision OV5640 support
[linux-2.6.git] / drivers / tty / sysrq.c
1 /*
2  *      Linux Magic System Request Key Hacks
3  *
4  *      (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
5  *      based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
6  *
7  *      (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
8  *      overhauled to use key registration
9  *      based upon discusions in irc://irc.openprojects.net/#kernelnewbies
10  *
11  *      Copyright (c) 2010 Dmitry Torokhov
12  *      Input handler conversion
13  */
14
15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
17 #include <linux/sched.h>
18 #include <linux/interrupt.h>
19 #include <linux/mm.h>
20 #include <linux/fs.h>
21 #include <linux/mount.h>
22 #include <linux/kdev_t.h>
23 #include <linux/major.h>
24 #include <linux/reboot.h>
25 #include <linux/sysrq.h>
26 #include <linux/kbd_kern.h>
27 #include <linux/proc_fs.h>
28 #include <linux/nmi.h>
29 #include <linux/quotaops.h>
30 #include <linux/perf_event.h>
31 #include <linux/kernel.h>
32 #include <linux/module.h>
33 #include <linux/suspend.h>
34 #include <linux/writeback.h>
35 #include <linux/buffer_head.h>          /* for fsync_bdev() */
36 #include <linux/swap.h>
37 #include <linux/spinlock.h>
38 #include <linux/vt_kern.h>
39 #include <linux/workqueue.h>
40 #include <linux/hrtimer.h>
41 #include <linux/oom.h>
42 #include <linux/slab.h>
43 #include <linux/input.h>
44
45 #include <asm/ptrace.h>
46 #include <asm/irq_regs.h>
47
48 /* Whether we react on sysrq keys or just ignore them */
49 static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE;
50 static bool __read_mostly sysrq_always_enabled;
51
52 static bool sysrq_on(void)
53 {
54         return sysrq_enabled || sysrq_always_enabled;
55 }
56
57 /*
58  * A value of 1 means 'all', other nonzero values are an op mask:
59  */
60 static bool sysrq_on_mask(int mask)
61 {
62         return sysrq_always_enabled ||
63                sysrq_enabled == 1 ||
64                (sysrq_enabled & mask);
65 }
66
67 static int __init sysrq_always_enabled_setup(char *str)
68 {
69         sysrq_always_enabled = true;
70         pr_info("sysrq always enabled.\n");
71
72         return 1;
73 }
74
75 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
76
77
78 static void sysrq_handle_loglevel(int key)
79 {
80         int i;
81
82         i = key - '0';
83         console_loglevel = 7;
84         printk("Loglevel set to %d\n", i);
85         console_loglevel = i;
86 }
87 static struct sysrq_key_op sysrq_loglevel_op = {
88         .handler        = sysrq_handle_loglevel,
89         .help_msg       = "loglevel(0-9)",
90         .action_msg     = "Changing Loglevel",
91         .enable_mask    = SYSRQ_ENABLE_LOG,
92 };
93
94 #ifdef CONFIG_VT
95 static void sysrq_handle_SAK(int key)
96 {
97         struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
98         schedule_work(SAK_work);
99 }
100 static struct sysrq_key_op sysrq_SAK_op = {
101         .handler        = sysrq_handle_SAK,
102         .help_msg       = "saK",
103         .action_msg     = "SAK",
104         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
105 };
106 #else
107 #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
108 #endif
109
110 #ifdef CONFIG_VT
111 static void sysrq_handle_unraw(int key)
112 {
113         struct kbd_struct *kbd = &kbd_table[fg_console];
114
115         if (kbd)
116                 kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE;
117 }
118 static struct sysrq_key_op sysrq_unraw_op = {
119         .handler        = sysrq_handle_unraw,
120         .help_msg       = "unRaw",
121         .action_msg     = "Keyboard mode set to system default",
122         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
123 };
124 #else
125 #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
126 #endif /* CONFIG_VT */
127
128 static void sysrq_handle_crash(int key)
129 {
130         char *killer = NULL;
131
132         panic_on_oops = 1;      /* force panic */
133         wmb();
134         *killer = 1;
135 }
136 static struct sysrq_key_op sysrq_crash_op = {
137         .handler        = sysrq_handle_crash,
138         .help_msg       = "Crash",
139         .action_msg     = "Trigger a crash",
140         .enable_mask    = SYSRQ_ENABLE_DUMP,
141 };
142
143 static void sysrq_handle_reboot(int key)
144 {
145         lockdep_off();
146         local_irq_enable();
147         emergency_restart();
148 }
149 static struct sysrq_key_op sysrq_reboot_op = {
150         .handler        = sysrq_handle_reboot,
151         .help_msg       = "reBoot",
152         .action_msg     = "Resetting",
153         .enable_mask    = SYSRQ_ENABLE_BOOT,
154 };
155
156 static void sysrq_handle_sync(int key)
157 {
158         emergency_sync();
159 }
160 static struct sysrq_key_op sysrq_sync_op = {
161         .handler        = sysrq_handle_sync,
162         .help_msg       = "Sync",
163         .action_msg     = "Emergency Sync",
164         .enable_mask    = SYSRQ_ENABLE_SYNC,
165 };
166
167 static void sysrq_handle_show_timers(int key)
168 {
169         sysrq_timer_list_show();
170 }
171
172 static struct sysrq_key_op sysrq_show_timers_op = {
173         .handler        = sysrq_handle_show_timers,
174         .help_msg       = "show-all-timers(Q)",
175         .action_msg     = "Show clockevent devices & pending hrtimers (no others)",
176 };
177
178 static void sysrq_handle_mountro(int key)
179 {
180         emergency_remount();
181 }
182 static struct sysrq_key_op sysrq_mountro_op = {
183         .handler        = sysrq_handle_mountro,
184         .help_msg       = "Unmount",
185         .action_msg     = "Emergency Remount R/O",
186         .enable_mask    = SYSRQ_ENABLE_REMOUNT,
187 };
188
189 #ifdef CONFIG_LOCKDEP
190 static void sysrq_handle_showlocks(int key)
191 {
192         debug_show_all_locks();
193 }
194
195 static struct sysrq_key_op sysrq_showlocks_op = {
196         .handler        = sysrq_handle_showlocks,
197         .help_msg       = "show-all-locks(D)",
198         .action_msg     = "Show Locks Held",
199 };
200 #else
201 #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
202 #endif
203
204 #ifdef CONFIG_SMP
205 static DEFINE_SPINLOCK(show_lock);
206
207 static void showacpu(void *dummy)
208 {
209         unsigned long flags;
210
211         /* Idle CPUs have no interesting backtrace. */
212         if (idle_cpu(smp_processor_id()))
213                 return;
214
215         spin_lock_irqsave(&show_lock, flags);
216         printk(KERN_INFO "CPU%d:\n", smp_processor_id());
217         show_stack(NULL, NULL);
218         spin_unlock_irqrestore(&show_lock, flags);
219 }
220
221 static void sysrq_showregs_othercpus(struct work_struct *dummy)
222 {
223         smp_call_function(showacpu, NULL, 0);
224 }
225
226 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
227
228 static void sysrq_handle_showallcpus(int key)
229 {
230         /*
231          * Fall back to the workqueue based printing if the
232          * backtrace printing did not succeed or the
233          * architecture has no support for it:
234          */
235         if (!trigger_all_cpu_backtrace()) {
236                 struct pt_regs *regs = get_irq_regs();
237
238                 if (regs) {
239                         printk(KERN_INFO "CPU%d:\n", smp_processor_id());
240                         show_regs(regs);
241                 }
242                 schedule_work(&sysrq_showallcpus);
243         }
244 }
245
246 static struct sysrq_key_op sysrq_showallcpus_op = {
247         .handler        = sysrq_handle_showallcpus,
248         .help_msg       = "show-backtrace-all-active-cpus(L)",
249         .action_msg     = "Show backtrace of all active CPUs",
250         .enable_mask    = SYSRQ_ENABLE_DUMP,
251 };
252 #endif
253
254 static void sysrq_handle_showregs(int key)
255 {
256         struct pt_regs *regs = get_irq_regs();
257         if (regs)
258                 show_regs(regs);
259         perf_event_print_debug();
260 }
261 static struct sysrq_key_op sysrq_showregs_op = {
262         .handler        = sysrq_handle_showregs,
263         .help_msg       = "show-registers(P)",
264         .action_msg     = "Show Regs",
265         .enable_mask    = SYSRQ_ENABLE_DUMP,
266 };
267
268 static void sysrq_handle_showstate(int key)
269 {
270         show_state();
271 }
272 static struct sysrq_key_op sysrq_showstate_op = {
273         .handler        = sysrq_handle_showstate,
274         .help_msg       = "show-task-states(T)",
275         .action_msg     = "Show State",
276         .enable_mask    = SYSRQ_ENABLE_DUMP,
277 };
278
279 static void sysrq_handle_showstate_blocked(int key)
280 {
281         show_state_filter(TASK_UNINTERRUPTIBLE);
282 }
283 static struct sysrq_key_op sysrq_showstate_blocked_op = {
284         .handler        = sysrq_handle_showstate_blocked,
285         .help_msg       = "show-blocked-tasks(W)",
286         .action_msg     = "Show Blocked State",
287         .enable_mask    = SYSRQ_ENABLE_DUMP,
288 };
289
290 #ifdef CONFIG_TRACING
291 #include <linux/ftrace.h>
292
293 static void sysrq_ftrace_dump(int key)
294 {
295         ftrace_dump(DUMP_ALL);
296 }
297 static struct sysrq_key_op sysrq_ftrace_dump_op = {
298         .handler        = sysrq_ftrace_dump,
299         .help_msg       = "dump-ftrace-buffer(Z)",
300         .action_msg     = "Dump ftrace buffer",
301         .enable_mask    = SYSRQ_ENABLE_DUMP,
302 };
303 #else
304 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
305 #endif
306
307 static void sysrq_handle_showmem(int key)
308 {
309         show_mem(0);
310 }
311 static struct sysrq_key_op sysrq_showmem_op = {
312         .handler        = sysrq_handle_showmem,
313         .help_msg       = "show-memory-usage(M)",
314         .action_msg     = "Show Memory",
315         .enable_mask    = SYSRQ_ENABLE_DUMP,
316 };
317
318 /*
319  * Signal sysrq helper function.  Sends a signal to all user processes.
320  */
321 static void send_sig_all(int sig)
322 {
323         struct task_struct *p;
324
325         for_each_process(p) {
326                 if (p->mm && !is_global_init(p))
327                         /* Not swapper, init nor kernel thread */
328                         force_sig(sig, p);
329         }
330 }
331
332 static void sysrq_handle_term(int key)
333 {
334         send_sig_all(SIGTERM);
335         console_loglevel = 8;
336 }
337 static struct sysrq_key_op sysrq_term_op = {
338         .handler        = sysrq_handle_term,
339         .help_msg       = "terminate-all-tasks(E)",
340         .action_msg     = "Terminate All Tasks",
341         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
342 };
343
344 static void moom_callback(struct work_struct *ignored)
345 {
346         out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL);
347 }
348
349 static DECLARE_WORK(moom_work, moom_callback);
350
351 static void sysrq_handle_moom(int key)
352 {
353         schedule_work(&moom_work);
354 }
355 static struct sysrq_key_op sysrq_moom_op = {
356         .handler        = sysrq_handle_moom,
357         .help_msg       = "memory-full-oom-kill(F)",
358         .action_msg     = "Manual OOM execution",
359         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
360 };
361
362 #ifdef CONFIG_BLOCK
363 static void sysrq_handle_thaw(int key)
364 {
365         emergency_thaw_all();
366 }
367 static struct sysrq_key_op sysrq_thaw_op = {
368         .handler        = sysrq_handle_thaw,
369         .help_msg       = "thaw-filesystems(J)",
370         .action_msg     = "Emergency Thaw of all frozen filesystems",
371         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
372 };
373 #endif
374
375 static void sysrq_handle_kill(int key)
376 {
377         send_sig_all(SIGKILL);
378         console_loglevel = 8;
379 }
380 static struct sysrq_key_op sysrq_kill_op = {
381         .handler        = sysrq_handle_kill,
382         .help_msg       = "kill-all-tasks(I)",
383         .action_msg     = "Kill All Tasks",
384         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
385 };
386
387 static void sysrq_handle_unrt(int key)
388 {
389         normalize_rt_tasks();
390 }
391 static struct sysrq_key_op sysrq_unrt_op = {
392         .handler        = sysrq_handle_unrt,
393         .help_msg       = "nice-all-RT-tasks(N)",
394         .action_msg     = "Nice All RT Tasks",
395         .enable_mask    = SYSRQ_ENABLE_RTNICE,
396 };
397
398 /* Key Operations table and lock */
399 static DEFINE_SPINLOCK(sysrq_key_table_lock);
400
401 static struct sysrq_key_op *sysrq_key_table[36] = {
402         &sysrq_loglevel_op,             /* 0 */
403         &sysrq_loglevel_op,             /* 1 */
404         &sysrq_loglevel_op,             /* 2 */
405         &sysrq_loglevel_op,             /* 3 */
406         &sysrq_loglevel_op,             /* 4 */
407         &sysrq_loglevel_op,             /* 5 */
408         &sysrq_loglevel_op,             /* 6 */
409         &sysrq_loglevel_op,             /* 7 */
410         &sysrq_loglevel_op,             /* 8 */
411         &sysrq_loglevel_op,             /* 9 */
412
413         /*
414          * a: Don't use for system provided sysrqs, it is handled specially on
415          * sparc and will never arrive.
416          */
417         NULL,                           /* a */
418         &sysrq_reboot_op,               /* b */
419         &sysrq_crash_op,                /* c & ibm_emac driver debug */
420         &sysrq_showlocks_op,            /* d */
421         &sysrq_term_op,                 /* e */
422         &sysrq_moom_op,                 /* f */
423         /* g: May be registered for the kernel debugger */
424         NULL,                           /* g */
425         NULL,                           /* h - reserved for help */
426         &sysrq_kill_op,                 /* i */
427 #ifdef CONFIG_BLOCK
428         &sysrq_thaw_op,                 /* j */
429 #else
430         NULL,                           /* j */
431 #endif
432         &sysrq_SAK_op,                  /* k */
433 #ifdef CONFIG_SMP
434         &sysrq_showallcpus_op,          /* l */
435 #else
436         NULL,                           /* l */
437 #endif
438         &sysrq_showmem_op,              /* m */
439         &sysrq_unrt_op,                 /* n */
440         /* o: This will often be registered as 'Off' at init time */
441         NULL,                           /* o */
442         &sysrq_showregs_op,             /* p */
443         &sysrq_show_timers_op,          /* q */
444         &sysrq_unraw_op,                /* r */
445         &sysrq_sync_op,                 /* s */
446         &sysrq_showstate_op,            /* t */
447         &sysrq_mountro_op,              /* u */
448         /* v: May be registered for frame buffer console restore */
449         NULL,                           /* v */
450         &sysrq_showstate_blocked_op,    /* w */
451         /* x: May be registered on ppc/powerpc for xmon */
452         NULL,                           /* x */
453         /* y: May be registered on sparc64 for global register dump */
454         NULL,                           /* y */
455         &sysrq_ftrace_dump_op,          /* z */
456 };
457
458 /* key2index calculation, -1 on invalid index */
459 static int sysrq_key_table_key2index(int key)
460 {
461         int retval;
462
463         if ((key >= '0') && (key <= '9'))
464                 retval = key - '0';
465         else if ((key >= 'a') && (key <= 'z'))
466                 retval = key + 10 - 'a';
467         else
468                 retval = -1;
469         return retval;
470 }
471
472 /*
473  * get and put functions for the table, exposed to modules.
474  */
475 struct sysrq_key_op *__sysrq_get_key_op(int key)
476 {
477         struct sysrq_key_op *op_p = NULL;
478         int i;
479
480         i = sysrq_key_table_key2index(key);
481         if (i != -1)
482                 op_p = sysrq_key_table[i];
483
484         return op_p;
485 }
486
487 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
488 {
489         int i = sysrq_key_table_key2index(key);
490
491         if (i != -1)
492                 sysrq_key_table[i] = op_p;
493 }
494
495 void __handle_sysrq(int key, bool check_mask)
496 {
497         struct sysrq_key_op *op_p;
498         int orig_log_level;
499         int i;
500         unsigned long flags;
501
502         spin_lock_irqsave(&sysrq_key_table_lock, flags);
503         /*
504          * Raise the apparent loglevel to maximum so that the sysrq header
505          * is shown to provide the user with positive feedback.  We do not
506          * simply emit this at KERN_EMERG as that would change message
507          * routing in the consumers of /proc/kmsg.
508          */
509         orig_log_level = console_loglevel;
510         console_loglevel = 7;
511         printk(KERN_INFO "SysRq : ");
512
513         op_p = __sysrq_get_key_op(key);
514         if (op_p) {
515                 /*
516                  * Should we check for enabled operations (/proc/sysrq-trigger
517                  * should not) and is the invoked operation enabled?
518                  */
519                 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
520                         printk("%s\n", op_p->action_msg);
521                         console_loglevel = orig_log_level;
522                         op_p->handler(key);
523                 } else {
524                         printk("This sysrq operation is disabled.\n");
525                 }
526         } else {
527                 printk("HELP : ");
528                 /* Only print the help msg once per handler */
529                 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
530                         if (sysrq_key_table[i]) {
531                                 int j;
532
533                                 for (j = 0; sysrq_key_table[i] !=
534                                                 sysrq_key_table[j]; j++)
535                                         ;
536                                 if (j != i)
537                                         continue;
538                                 printk("%s ", sysrq_key_table[i]->help_msg);
539                         }
540                 }
541                 printk("\n");
542                 console_loglevel = orig_log_level;
543         }
544         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
545 }
546
547 void handle_sysrq(int key)
548 {
549         if (sysrq_on())
550                 __handle_sysrq(key, true);
551 }
552 EXPORT_SYMBOL(handle_sysrq);
553
554 #ifdef CONFIG_INPUT
555
556 /* Simple translation table for the SysRq keys */
557 static const unsigned char sysrq_xlate[KEY_CNT] =
558         "\000\0331234567890-=\177\t"                    /* 0x00 - 0x0f */
559         "qwertyuiop[]\r\000as"                          /* 0x10 - 0x1f */
560         "dfghjkl;'`\000\\zxcv"                          /* 0x20 - 0x2f */
561         "bnm,./\000*\000 \000\201\202\203\204\205"      /* 0x30 - 0x3f */
562         "\206\207\210\211\212\000\000789-456+1"         /* 0x40 - 0x4f */
563         "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
564         "\r\000/";                                      /* 0x60 - 0x6f */
565
566 struct sysrq_state {
567         struct input_handle handle;
568         struct work_struct reinject_work;
569         unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
570         unsigned int alt;
571         unsigned int alt_use;
572         bool active;
573         bool need_reinject;
574         bool reinjecting;
575 };
576
577 static void sysrq_reinject_alt_sysrq(struct work_struct *work)
578 {
579         struct sysrq_state *sysrq =
580                         container_of(work, struct sysrq_state, reinject_work);
581         struct input_handle *handle = &sysrq->handle;
582         unsigned int alt_code = sysrq->alt_use;
583
584         if (sysrq->need_reinject) {
585                 /* we do not want the assignment to be reordered */
586                 sysrq->reinjecting = true;
587                 mb();
588
589                 /* Simulate press and release of Alt + SysRq */
590                 input_inject_event(handle, EV_KEY, alt_code, 1);
591                 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
592                 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
593
594                 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
595                 input_inject_event(handle, EV_KEY, alt_code, 0);
596                 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
597
598                 mb();
599                 sysrq->reinjecting = false;
600         }
601 }
602
603 static bool sysrq_filter(struct input_handle *handle,
604                          unsigned int type, unsigned int code, int value)
605 {
606         struct sysrq_state *sysrq = handle->private;
607         bool was_active = sysrq->active;
608         bool suppress;
609
610         /*
611          * Do not filter anything if we are in the process of re-injecting
612          * Alt+SysRq combination.
613          */
614         if (sysrq->reinjecting)
615                 return false;
616
617         switch (type) {
618
619         case EV_SYN:
620                 suppress = false;
621                 break;
622
623         case EV_KEY:
624                 switch (code) {
625
626                 case KEY_LEFTALT:
627                 case KEY_RIGHTALT:
628                         if (!value) {
629                                 /* One of ALTs is being released */
630                                 if (sysrq->active && code == sysrq->alt_use)
631                                         sysrq->active = false;
632
633                                 sysrq->alt = KEY_RESERVED;
634
635                         } else if (value != 2) {
636                                 sysrq->alt = code;
637                                 sysrq->need_reinject = false;
638                         }
639                         break;
640
641                 case KEY_SYSRQ:
642                         if (value == 1 && sysrq->alt != KEY_RESERVED) {
643                                 sysrq->active = true;
644                                 sysrq->alt_use = sysrq->alt;
645                                 /*
646                                  * If nothing else will be pressed we'll need
647                                  * to re-inject Alt-SysRq keysroke.
648                                  */
649                                 sysrq->need_reinject = true;
650                         }
651
652                         /*
653                          * Pretend that sysrq was never pressed at all. This
654                          * is needed to properly handle KGDB which will try
655                          * to release all keys after exiting debugger. If we
656                          * do not clear key bit it KGDB will end up sending
657                          * release events for Alt and SysRq, potentially
658                          * triggering print screen function.
659                          */
660                         if (sysrq->active)
661                                 clear_bit(KEY_SYSRQ, handle->dev->key);
662
663                         break;
664
665                 default:
666                         if (sysrq->active && value && value != 2) {
667                                 sysrq->need_reinject = false;
668                                 __handle_sysrq(sysrq_xlate[code], true);
669                         }
670                         break;
671                 }
672
673                 suppress = sysrq->active;
674
675                 if (!sysrq->active) {
676                         /*
677                          * If we are not suppressing key presses keep track of
678                          * keyboard state so we can release keys that have been
679                          * pressed before entering SysRq mode.
680                          */
681                         if (value)
682                                 set_bit(code, sysrq->key_down);
683                         else
684                                 clear_bit(code, sysrq->key_down);
685
686                         if (was_active)
687                                 schedule_work(&sysrq->reinject_work);
688
689                 } else if (value == 0 &&
690                            test_and_clear_bit(code, sysrq->key_down)) {
691                         /*
692                          * Pass on release events for keys that was pressed before
693                          * entering SysRq mode.
694                          */
695                         suppress = false;
696                 }
697                 break;
698
699         default:
700                 suppress = sysrq->active;
701                 break;
702         }
703
704         return suppress;
705 }
706
707 static int sysrq_connect(struct input_handler *handler,
708                          struct input_dev *dev,
709                          const struct input_device_id *id)
710 {
711         struct sysrq_state *sysrq;
712         int error;
713
714         sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
715         if (!sysrq)
716                 return -ENOMEM;
717
718         INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
719
720         sysrq->handle.dev = dev;
721         sysrq->handle.handler = handler;
722         sysrq->handle.name = "sysrq";
723         sysrq->handle.private = sysrq;
724
725         error = input_register_handle(&sysrq->handle);
726         if (error) {
727                 pr_err("Failed to register input sysrq handler, error %d\n",
728                         error);
729                 goto err_free;
730         }
731
732         error = input_open_device(&sysrq->handle);
733         if (error) {
734                 pr_err("Failed to open input device, error %d\n", error);
735                 goto err_unregister;
736         }
737
738         return 0;
739
740  err_unregister:
741         input_unregister_handle(&sysrq->handle);
742  err_free:
743         kfree(sysrq);
744         return error;
745 }
746
747 static void sysrq_disconnect(struct input_handle *handle)
748 {
749         struct sysrq_state *sysrq = handle->private;
750
751         input_close_device(handle);
752         cancel_work_sync(&sysrq->reinject_work);
753         input_unregister_handle(handle);
754         kfree(sysrq);
755 }
756
757 /*
758  * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
759  * keyboards have SysRq key predefined and so user may add it to keymap
760  * later, but we expect all such keyboards to have left alt.
761  */
762 static const struct input_device_id sysrq_ids[] = {
763         {
764                 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
765                                 INPUT_DEVICE_ID_MATCH_KEYBIT,
766                 .evbit = { BIT_MASK(EV_KEY) },
767                 .keybit = { BIT_MASK(KEY_LEFTALT) },
768         },
769         { },
770 };
771
772 static struct input_handler sysrq_handler = {
773         .filter         = sysrq_filter,
774         .connect        = sysrq_connect,
775         .disconnect     = sysrq_disconnect,
776         .name           = "sysrq",
777         .id_table       = sysrq_ids,
778 };
779
780 static bool sysrq_handler_registered;
781
782 static inline void sysrq_register_handler(void)
783 {
784         int error;
785
786         error = input_register_handler(&sysrq_handler);
787         if (error)
788                 pr_err("Failed to register input handler, error %d", error);
789         else
790                 sysrq_handler_registered = true;
791 }
792
793 static inline void sysrq_unregister_handler(void)
794 {
795         if (sysrq_handler_registered) {
796                 input_unregister_handler(&sysrq_handler);
797                 sysrq_handler_registered = false;
798         }
799 }
800
801 #else
802
803 static inline void sysrq_register_handler(void)
804 {
805 }
806
807 static inline void sysrq_unregister_handler(void)
808 {
809 }
810
811 #endif /* CONFIG_INPUT */
812
813 int sysrq_toggle_support(int enable_mask)
814 {
815         bool was_enabled = sysrq_on();
816
817         sysrq_enabled = enable_mask;
818
819         if (was_enabled != sysrq_on()) {
820                 if (sysrq_on())
821                         sysrq_register_handler();
822                 else
823                         sysrq_unregister_handler();
824         }
825
826         return 0;
827 }
828
829 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
830                                 struct sysrq_key_op *remove_op_p)
831 {
832         int retval;
833         unsigned long flags;
834
835         spin_lock_irqsave(&sysrq_key_table_lock, flags);
836         if (__sysrq_get_key_op(key) == remove_op_p) {
837                 __sysrq_put_key_op(key, insert_op_p);
838                 retval = 0;
839         } else {
840                 retval = -1;
841         }
842         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
843         return retval;
844 }
845
846 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
847 {
848         return __sysrq_swap_key_ops(key, op_p, NULL);
849 }
850 EXPORT_SYMBOL(register_sysrq_key);
851
852 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
853 {
854         return __sysrq_swap_key_ops(key, NULL, op_p);
855 }
856 EXPORT_SYMBOL(unregister_sysrq_key);
857
858 #ifdef CONFIG_PROC_FS
859 /*
860  * writing 'C' to /proc/sysrq-trigger is like sysrq-C
861  */
862 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
863                                    size_t count, loff_t *ppos)
864 {
865         if (count) {
866                 char c;
867
868                 if (get_user(c, buf))
869                         return -EFAULT;
870                 __handle_sysrq(c, false);
871         }
872
873         return count;
874 }
875
876 static const struct file_operations proc_sysrq_trigger_operations = {
877         .write          = write_sysrq_trigger,
878         .llseek         = noop_llseek,
879 };
880
881 static void sysrq_init_procfs(void)
882 {
883         if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
884                          &proc_sysrq_trigger_operations))
885                 pr_err("Failed to register proc interface\n");
886 }
887
888 #else
889
890 static inline void sysrq_init_procfs(void)
891 {
892 }
893
894 #endif /* CONFIG_PROC_FS */
895
896 static int __init sysrq_init(void)
897 {
898         sysrq_init_procfs();
899
900         if (sysrq_on())
901                 sysrq_register_handler();
902
903         return 0;
904 }
905 module_init(sysrq_init);