1 /*
2 * Copyright (C) 2009 Imagination Technologies
3 *
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
6 * for more details.
7 *
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.
16 *
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.
22 *
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.
27 */
28 #include <linux/export.h>
29 #include <linux/hardirq.h>
30 #include <linux/irq.h>
31 #include <linux/kernel.h>
32 #include <linux/mm.h>
33 #include <linux/types.h>
34
35 #include <asm/traps.h>
36
37 /*
38 * All accesses/manipulations of kick_handlers_list should be
39 * performed while holding kick_handlers_lock.
40 */
41 static DEFINE_SPINLOCK(kick_handlers_lock);
42 static LIST_HEAD(kick_handlers_list);
43
kick_register_func(struct kick_irq_handler * kh)44 void kick_register_func(struct kick_irq_handler *kh)
45 {
46 unsigned long flags;
47
48 spin_lock_irqsave(&kick_handlers_lock, flags);
49
50 list_add_tail(&kh->list, &kick_handlers_list);
51
52 spin_unlock_irqrestore(&kick_handlers_lock, flags);
53 }
54 EXPORT_SYMBOL(kick_register_func);
55
kick_unregister_func(struct kick_irq_handler * kh)56 void kick_unregister_func(struct kick_irq_handler *kh)
57 {
58 unsigned long flags;
59
60 spin_lock_irqsave(&kick_handlers_lock, flags);
61
62 list_del(&kh->list);
63
64 spin_unlock_irqrestore(&kick_handlers_lock, flags);
65 }
66 EXPORT_SYMBOL(kick_unregister_func);
67
68 TBIRES
kick_handler(TBIRES State,int SigNum,int Triggers,int Inst,PTBI pTBI)69 kick_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI)
70 {
71 struct pt_regs *old_regs;
72 struct kick_irq_handler *kh;
73 struct list_head *lh;
74 int handled = 0;
75 TBIRES ret;
76
77 head_end(State, ~INTS_OFF_MASK);
78
79 /* If we interrupted user code handle any critical sections. */
80 if (State.Sig.SaveMask & TBICTX_PRIV_BIT)
81 restart_critical_section(State);
82
83 trace_hardirqs_off();
84
85 old_regs = set_irq_regs((struct pt_regs *)State.Sig.pCtx);
86 irq_enter();
87
88 /*
89 * There is no need to disable interrupts here because we
90 * can't nest KICK interrupts in a KICK interrupt handler.
91 */
92 spin_lock(&kick_handlers_lock);
93
94 list_for_each(lh, &kick_handlers_list) {
95 kh = list_entry(lh, struct kick_irq_handler, list);
96
97 ret = kh->func(State, SigNum, Triggers, Inst, pTBI, &handled);
98 if (handled)
99 break;
100 }
101
102 spin_unlock(&kick_handlers_lock);
103
104 WARN_ON(!handled);
105
106 irq_exit();
107 set_irq_regs(old_regs);
108
109 return tail_end(ret);
110 }
111