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