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1 /*
2  * linux/kernel/irq/resend.c
3  *
4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5  * Copyright (C) 2005-2006, Thomas Gleixner
6  *
7  * This file contains the IRQ-resend code
8  *
9  * If the interrupt is waiting to be processed, we try to re-run it.
10  * We can't directly run it from here since the caller might be in an
11  * interrupt-protected region. Not all irq controller chips can
12  * retrigger interrupts at the hardware level, so in those cases
13  * we allow the resending of IRQs via a tasklet.
14  */
15
16 #include <linux/irq.h>
17 #include <linux/module.h>
18 #include <linux/random.h>
19 #include <linux/interrupt.h>
20
21 #include "internals.h"
22
23 #ifdef CONFIG_HARDIRQS_SW_RESEND
24
25 /* Bitmap to handle software resend of interrupts: */
26 static DECLARE_BITMAP(irqs_resend, IRQ_BITMAP_BITS);
27
28 /*
29  * Run software resends of IRQ's
30  */
31 static void resend_irqs(unsigned long arg)
32 {
33         struct irq_desc *desc;
34         int irq;
35
36         while (!bitmap_empty(irqs_resend, nr_irqs)) {
37                 irq = find_first_bit(irqs_resend, nr_irqs);
38                 clear_bit(irq, irqs_resend);
39                 desc = irq_to_desc(irq);
40                 local_irq_disable();
41                 desc->handle_irq(desc);
42                 local_irq_enable();
43         }
44 }
45
46 /* Tasklet to handle resend: */
47 static DECLARE_TASKLET(resend_tasklet, resend_irqs, 0);
48
49 #endif
50
51 /*
52  * IRQ resend
53  *
54  * Is called with interrupts disabled and desc->lock held.
55  */
56 void check_irq_resend(struct irq_desc *desc)
57 {
58         /*
59          * We do not resend level type interrupts. Level type
60          * interrupts are resent by hardware when they are still
61          * active. Clear the pending bit so suspend/resume does not
62          * get confused.
63          */
64         if (irq_settings_is_level(desc)) {
65                 desc->istate &= ~IRQS_PENDING;
66                 return;
67         }
68         if (desc->istate & IRQS_REPLAY)
69                 return;
70         if (desc->istate & IRQS_PENDING) {
71                 desc->istate &= ~IRQS_PENDING;
72                 desc->istate |= IRQS_REPLAY;
73
74                 if (!desc->irq_data.chip->irq_retrigger ||
75                     !desc->irq_data.chip->irq_retrigger(&desc->irq_data)) {
76 #ifdef CONFIG_HARDIRQS_SW_RESEND
77                         unsigned int irq = irq_desc_get_irq(desc);
78
79                         /*
80                          * If the interrupt is running in the thread
81                          * context of the parent irq we need to be
82                          * careful, because we cannot trigger it
83                          * directly.
84                          */
85                         if (irq_settings_is_nested_thread(desc)) {
86                                 /*
87                                  * If the parent_irq is valid, we
88                                  * retrigger the parent, otherwise we
89                                  * do nothing.
90                                  */
91                                 if (!desc->parent_irq)
92                                         return;
93                                 irq = desc->parent_irq;
94                         }
95                         /* Set it pending and activate the softirq: */
96                         set_bit(irq, irqs_resend);
97                         tasklet_schedule(&resend_tasklet);
98 #endif
99                 }
100         }
101 }