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/ftrace.h>
  38
  39 #include <asm/system.h>
  40 #include <asm/mach/arch.h>
  41 #include <asm/mach/irq.h>
  42 #include <asm/mach/time.h>
  43
  44 /*
  45  * No architecture-specific irq_finish function defined in arm/arch/irqs.h.
  46  */
  47 #ifndef irq_finish
  48 #define irq_finish(irq) do { } while (0)
  49 #endif
  50
  51 unsigned long irq_err_count;
  52
  53 int arch_show_interrupts(struct seq_file *p, int prec)
  54 {
  55 #ifdef CONFIG_FIQ
  56         show_fiq_list(p, prec);
  57 #endif
  58 #ifdef CONFIG_SMP
  59         show_ipi_list(p, prec);
  60 #endif
  61 #ifdef CONFIG_LOCAL_TIMERS
  62         show_local_irqs(p, prec);
  63 #endif
  64         seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count);
  65         return 0;
  66 }
  67
  68 /*
  69  * handle_IRQ handles all hardware IRQ's.  Decoded IRQs should
  70  * not come via this function.  Instead, they should provide their
  71  * own 'handler'.  Used by platform code implementing C-based 1st
  72  * level decoding.
  73  */
  74 void handle_IRQ(unsigned int irq, struct pt_regs *regs)
  75 {
  76         struct pt_regs *old_regs = set_irq_regs(regs);
  77
  78         irq_enter();
  79
  80         /*
  81          * Some hardware gives randomly wrong interrupts.  Rather
  82          * than crashing, do something sensible.
  83          */
  84         if (unlikely(irq >= nr_irqs)) {
  85                 if (printk_ratelimit())
  86                         printk(KERN_WARNING "Bad IRQ%u\n", irq);
  87                 ack_bad_irq(irq);
  88         } else {
  89                 generic_handle_irq(irq);
  90         }
  91
  92         /* AT91 specific workaround */
  93         irq_finish(irq);
  94
  95         irq_exit();
  96         set_irq_regs(old_regs);
  97 }
  98
  99 /*
 100  * asm_do_IRQ is the interface to be used from assembly code.
 101  */
 102 asmlinkage void __exception_irq_entry
 103 asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
 104 {
 105         handle_IRQ(irq, regs);
 106 }
 107
 108 void set_irq_flags(unsigned int irq, unsigned int iflags)
 109 {
 110         unsigned long clr = 0, set = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
 111
 112         if (irq >= nr_irqs) {
 113                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
 114                 return;
 115         }
 116
 117         if (iflags & IRQF_VALID)
 118                 clr |= IRQ_NOREQUEST;
 119         if (iflags & IRQF_PROBE)
 120                 clr |= IRQ_NOPROBE;
 121         if (!(iflags & IRQF_NOAUTOEN))
 122                 clr |= IRQ_NOAUTOEN;
 123         /* Order is clear bits in "clr" then set bits in "set" */
 124         irq_modify_status(irq, clr, set & ~clr);
 125 }
 126
 127 void __init init_IRQ(void)
 128 {
 129         machine_desc->init_irq();
 130 }
 131
 132 #ifdef CONFIG_SPARSE_IRQ
 133 int __init arch_probe_nr_irqs(void)
 134 {
 135         nr_irqs = machine_desc->nr_irqs ? machine_desc->nr_irqs : NR_IRQS;
 136         return nr_irqs;
 137 }
 138 #endif
 139
 140 #ifdef CONFIG_HOTPLUG_CPU
 141
 142 static bool migrate_one_irq(struct irq_desc *desc)
 143 {
 144         struct irq_data *d = irq_desc_get_irq_data(desc);
 145         const struct cpumask *affinity = d->affinity;
 146         struct irq_chip *c;
 147         bool ret = false;
 148
 149         /*
 150          * If this is a per-CPU interrupt, or the affinity does not
 151          * include this CPU, then we have nothing to do.
 152          */
 153         if (irqd_is_per_cpu(d) || !cpumask_test_cpu(smp_processor_id(), affinity))
 154                 return false;
 155
 156         if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
 157                 affinity = cpu_online_mask;
 158                 ret = true;
 159         }
 160
 161         c = irq_data_get_irq_chip(d);
 162         if (c->irq_set_affinity)
 163                 c->irq_set_affinity(d, affinity, true);
 164         else
 165                 pr_debug("IRQ%u: unable to set affinity\n", d->irq);
 166
 167         return ret;
 168 }
 169
 170 /*
 171  * The current CPU has been marked offline.  Migrate IRQs off this CPU.
 172  * If the affinity settings do not allow other CPUs, force them onto any
 173  * available CPU.
 174  *
 175  * Note: we must iterate over all IRQs, whether they have an attached
 176  * action structure or not, as we need to get chained interrupts too.
 177  */
 178 void migrate_irqs(void)
 179 {
 180         unsigned int i;
 181         struct irq_desc *desc;
 182         unsigned long flags;
 183
 184         local_irq_save(flags);
 185
 186         for_each_irq_desc(i, desc) {
 187                 bool affinity_broken = false;
 188
 189                 if (!desc)
 190                         continue;
 191
 192                 raw_spin_lock(&desc->lock);
 193                 affinity_broken = migrate_one_irq(desc);
 194                 raw_spin_unlock(&desc->lock);
 195
 196                 if (affinity_broken && printk_ratelimit())
 197                         pr_warning("IRQ%u no longer affine to CPU%u\n", i,
 198                                 smp_processor_id());
 199         }
 200
 201         local_irq_restore(flags);
 202 }
 203 #endif /* CONFIG_HOTPLUG_CPU */