arch/arm/kernel/irq.c

   1 /*
   2  *  linux/arch/arm/kernel/irq.c
   3  *
   4  *  Copyright (C) 1992 Linus Torvalds
   5  *  Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
   6  *
   7  *  Support for Dynamic Tick Timer Copyright (C) 2004-2005 Nokia Corporation.
   8  *  Dynamic Tick Timer written by Tony Lindgren <tony@atomide.com> and
   9  *  Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>.
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  *
  15  *  This file contains the code used by various IRQ handling routines:
  16  *  asking for different IRQ's should be done through these routines
  17  *  instead of just grabbing them. Thus setups with different IRQ numbers
  18  *  shouldn't result in any weird surprises, and installing new handlers
  19  *  should be easier.
  20  *
  21  *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
  22  *  Naturally it's not a 1:1 relation, but there are similarities.
  23  */
  24 #include <linux/kernel_stat.h>
  25 #include <linux/signal.h>
  26 #include <linux/ioport.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/irq.h>
  29 #include <linux/random.h>
  30 #include <linux/smp.h>
  31 #include <linux/init.h>
  32 #include <linux/seq_file.h>
  33 #include <linux/errno.h>
  34 #include <linux/list.h>
  35 #include <linux/kallsyms.h>
  36 #include <linux/proc_fs.h>
  37 #include <linux/export.h>
  38
  39 #include <asm/exception.h>
  40 #include <asm/mach/arch.h>
  41 #include <asm/mach/irq.h>
  42 #include <asm/mach/time.h>
  43
  44 unsigned long irq_err_count;
  45
  46 int arch_show_interrupts(struct seq_file *p, int prec)
  47 {
  48 #ifdef CONFIG_FIQ
  49         show_fiq_list(p, prec);
  50 #endif
  51 #ifdef CONFIG_SMP
  52         show_ipi_list(p, prec);
  53 #endif
  54         seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count);
  55         return 0;
  56 }
  57
  58 /*
  59  * handle_IRQ handles all hardware IRQ's.  Decoded IRQs should
  60  * not come via this function.  Instead, they should provide their
  61  * own 'handler'.  Used by platform code implementing C-based 1st
  62  * level decoding.
  63  */
  64 void handle_IRQ(unsigned int irq, struct pt_regs *regs)
  65 {
  66         struct pt_regs *old_regs = set_irq_regs(regs);
  67
  68         irq_enter();
  69
  70         /*
  71          * Some hardware gives randomly wrong interrupts.  Rather
  72          * than crashing, do something sensible.
  73          */
  74         if (unlikely(irq >= nr_irqs)) {
  75                 if (printk_ratelimit())
  76                         printk(KERN_WARNING "Bad IRQ%u\n", irq);
  77                 ack_bad_irq(irq);
  78         } else {
  79                 generic_handle_irq(irq);
  80         }
  81
  82         irq_exit();
  83         set_irq_regs(old_regs);
  84 }
  85
  86 /*
  87  * asm_do_IRQ is the interface to be used from assembly code.
  88  */
  89 asmlinkage void __exception_irq_entry
  90 asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
  91 {
  92         handle_IRQ(irq, regs);
  93 }
  94
  95 void set_irq_flags(unsigned int irq, unsigned int iflags)
  96 {
  97         unsigned long clr = 0, set = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
  98
  99         if (irq >= nr_irqs) {
 100                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
 101                 return;
 102         }
 103
 104         if (iflags & IRQF_VALID)
 105                 clr |= IRQ_NOREQUEST;
 106         if (iflags & IRQF_PROBE)
 107                 clr |= IRQ_NOPROBE;
 108         if (!(iflags & IRQF_NOAUTOEN))
 109                 clr |= IRQ_NOAUTOEN;
 110         /* Order is clear bits in "clr" then set bits in "set" */
 111         irq_modify_status(irq, clr, set & ~clr);
 112 }
 113 EXPORT_SYMBOL_GPL(set_irq_flags);
 114
 115 void __init init_IRQ(void)
 116 {
 117         machine_desc->init_irq();
 118 }
 119
 120 #ifdef CONFIG_SPARSE_IRQ
 121 int __init arch_probe_nr_irqs(void)
 122 {
 123         nr_irqs = machine_desc->nr_irqs ? machine_desc->nr_irqs : NR_IRQS;
 124         return nr_irqs;
 125 }
 126 #endif
 127
 128 #ifdef CONFIG_HOTPLUG_CPU
 129
 130 static bool migrate_one_irq(struct irq_desc *desc)
 131 {
 132         struct irq_data *d = irq_desc_get_irq_data(desc);
 133         const struct cpumask *affinity = d->affinity;
 134         struct irq_chip *c;
 135         bool ret = false;
 136
 137         /*
 138          * If this is a per-CPU interrupt, or the affinity does not
 139          * include this CPU, then we have nothing to do.
 140          */
 141         if (irqd_is_per_cpu(d) || !cpumask_test_cpu(smp_processor_id(), affinity))
 142                 return false;
 143
 144         if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
 145                 affinity = cpu_online_mask;
 146                 ret = true;
 147         }
 148
 149         c = irq_data_get_irq_chip(d);
 150         if (!c->irq_set_affinity)
 151                 pr_debug("IRQ%u: unable to set affinity\n", d->irq);
 152         else if (c->irq_set_affinity(d, affinity, true) == IRQ_SET_MASK_OK && ret)
 153                 cpumask_copy(d->affinity, affinity);
 154
 155         return ret;
 156 }
 157
 158 /*
 159  * The current CPU has been marked offline.  Migrate IRQs off this CPU.
 160  * If the affinity settings do not allow other CPUs, force them onto any
 161  * available CPU.
 162  *
 163  * Note: we must iterate over all IRQs, whether they have an attached
 164  * action structure or not, as we need to get chained interrupts too.
 165  */
 166 void migrate_irqs(void)
 167 {
 168         unsigned int i;
 169         struct irq_desc *desc;
 170         unsigned long flags;
 171
 172         local_irq_save(flags);
 173
 174         for_each_irq_desc(i, desc) {
 175                 bool affinity_broken;
 176
 177                 raw_spin_lock(&desc->lock);
 178                 affinity_broken = migrate_one_irq(desc);
 179                 raw_spin_unlock(&desc->lock);
 180
 181                 if (affinity_broken && printk_ratelimit())
 182                         pr_warning("IRQ%u no longer affine to CPU%u\n", i,
 183                                 smp_processor_id());
 184         }
 185
 186         local_irq_restore(flags);
 187 }
 188 #endif /* CONFIG_HOTPLUG_CPU */