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