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