2 * Copyright (C) 2009 Imagination Technologies
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file COPYING in the main directory of this archive
8 * The Meta KICK interrupt mechanism is generally a useful feature, so
9 * we provide an interface for registering multiple interrupt
10 * handlers. All the registered interrupt handlers are "chained". When
11 * a KICK interrupt is received the first function in the list is
12 * called. If that interrupt handler cannot handle the KICK the next
13 * one is called, then the next until someone handles it (or we run
14 * out of functions). As soon as one function handles the interrupt no
15 * other handlers are called.
17 * The only downside of chaining interrupt handlers is that each
18 * handler must be able to detect whether the KICK was intended for it
19 * or not. For example, when the IPI handler runs and it sees that
20 * there are no IPI messages it must not signal that the KICK was
21 * handled, thereby giving the other handlers a chance to run.
23 * The reason that we provide our own interface for calling KICK
24 * handlers instead of using the generic kernel infrastructure is that
25 * the KICK handlers require access to a CPU's pTBI structure. So we
26 * pass it as an argument.
28 #include <linux/export.h>
29 #include <linux/kernel.h>
31 #include <linux/types.h>
33 #include <asm/traps.h>
36 * All accesses/manipulations of kick_handlers_list should be
37 * performed while holding kick_handlers_lock.
39 static DEFINE_SPINLOCK(kick_handlers_lock);
40 static LIST_HEAD(kick_handlers_list);
42 void kick_register_func(struct kick_irq_handler *kh)
46 spin_lock_irqsave(&kick_handlers_lock, flags);
48 list_add_tail(&kh->list, &kick_handlers_list);
50 spin_unlock_irqrestore(&kick_handlers_lock, flags);
52 EXPORT_SYMBOL(kick_register_func);
54 void kick_unregister_func(struct kick_irq_handler *kh)
58 spin_lock_irqsave(&kick_handlers_lock, flags);
62 spin_unlock_irqrestore(&kick_handlers_lock, flags);
64 EXPORT_SYMBOL(kick_unregister_func);
67 kick_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI)
69 struct kick_irq_handler *kh;
74 head_end(State, ~INTS_OFF_MASK);
76 /* If we interrupted user code handle any critical sections. */
77 if (State.Sig.SaveMask & TBICTX_PRIV_BIT)
78 restart_critical_section(State);
83 * There is no need to disable interrupts here because we
84 * can't nest KICK interrupts in a KICK interrupt handler.
86 spin_lock(&kick_handlers_lock);
88 list_for_each(lh, &kick_handlers_list) {
89 kh = list_entry(lh, struct kick_irq_handler, list);
91 ret = kh->func(State, SigNum, Triggers, Inst, pTBI, &handled);
96 spin_unlock(&kick_handlers_lock);
100 return tail_end(ret);