kernel/irq/resend.c

   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, NR_IRQS);
  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(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, unsigned int irq)
  57 {
  58         unsigned int status = desc->status;
  59
  60         /*
  61          * Make sure the interrupt is enabled, before resending it:
  62          */
  63         desc->chip->enable(irq);
  64
  65         /*
  66          * We do not resend level type interrupts. Level type
  67          * interrupts are resent by hardware when they are still
  68          * active.
  69          */
  70         if ((status & (IRQ_LEVEL | IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
  71                 desc->status = (status & ~IRQ_PENDING) | IRQ_REPLAY;
  72
  73                 if (!desc->chip->retrigger || !desc->chip->retrigger(irq)) {
  74 #ifdef CONFIG_HARDIRQS_SW_RESEND
  75                         /* Set it pending and activate the softirq: */
  76                         set_bit(irq, irqs_resend);
  77                         tasklet_schedule(&resend_tasklet);
  78 #endif
  79                 }
  80         }
  81 }