arch/mips/kernel/irq.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Code to handle x86 style IRQs plus some generic interrupt stuff.
   7  *
   8  * Copyright (C) 1992 Linus Torvalds
   9  * Copyright (C) 1994 - 2000 Ralf Baechle
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/delay.h>
  13 #include <linux/init.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/kernel_stat.h>
  16 #include <linux/proc_fs.h>
  17 #include <linux/mm.h>
  18 #include <linux/random.h>
  19 #include <linux/sched.h>
  20 #include <linux/seq_file.h>
  21 #include <linux/kallsyms.h>
  22 #include <linux/kgdb.h>
  23 #include <linux/ftrace.h>
  24
  25 #include <linux/atomic.h>
  26 #include <asm/system.h>
  27 #include <asm/uaccess.h>
  28
  29 #ifdef CONFIG_KGDB
  30 int kgdb_early_setup;
  31 #endif
  32
  33 static unsigned long irq_map[NR_IRQS / BITS_PER_LONG];
  34
  35 int allocate_irqno(void)
  36 {
  37         int irq;
  38
  39 again:
  40         irq = find_first_zero_bit(irq_map, NR_IRQS);
  41
  42         if (irq >= NR_IRQS)
  43                 return -ENOSPC;
  44
  45         if (test_and_set_bit(irq, irq_map))
  46                 goto again;
  47
  48         return irq;
  49 }
  50
  51 /*
  52  * Allocate the 16 legacy interrupts for i8259 devices.  This happens early
  53  * in the kernel initialization so treating allocation failure as BUG() is
  54  * ok.
  55  */
  56 void __init alloc_legacy_irqno(void)
  57 {
  58         int i;
  59
  60         for (i = 0; i <= 16; i++)
  61                 BUG_ON(test_and_set_bit(i, irq_map));
  62 }
  63
  64 void free_irqno(unsigned int irq)
  65 {
  66         smp_mb__before_clear_bit();
  67         clear_bit(irq, irq_map);
  68         smp_mb__after_clear_bit();
  69 }
  70
  71 /*
  72  * 'what should we do if we get a hw irq event on an illegal vector'.
  73  * each architecture has to answer this themselves.
  74  */
  75 void ack_bad_irq(unsigned int irq)
  76 {
  77         smtc_im_ack_irq(irq);
  78         printk("unexpected IRQ # %d\n", irq);
  79 }
  80
  81 atomic_t irq_err_count;
  82
  83 int arch_show_interrupts(struct seq_file *p, int prec)
  84 {
  85         seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
  86         return 0;
  87 }
  88
  89 asmlinkage void spurious_interrupt(void)
  90 {
  91         atomic_inc(&irq_err_count);
  92 }
  93
  94 void __init init_IRQ(void)
  95 {
  96         int i;
  97
  98 #ifdef CONFIG_KGDB
  99         if (kgdb_early_setup)
 100                 return;
 101 #endif
 102
 103         for (i = 0; i < NR_IRQS; i++)
 104                 irq_set_noprobe(i);
 105
 106         arch_init_irq();
 107
 108 #ifdef CONFIG_KGDB
 109         if (!kgdb_early_setup)
 110                 kgdb_early_setup = 1;
 111 #endif
 112 }
 113
 114 #ifdef DEBUG_STACKOVERFLOW
 115 static inline void check_stack_overflow(void)
 116 {
 117         unsigned long sp;
 118
 119         __asm__ __volatile__("move %0, $sp" : "=r" (sp));
 120         sp &= THREAD_MASK;
 121
 122         /*
 123          * Check for stack overflow: is there less than STACK_WARN free?
 124          * STACK_WARN is defined as 1/8 of THREAD_SIZE by default.
 125          */
 126         if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
 127                 printk("do_IRQ: stack overflow: %ld\n",
 128                        sp - sizeof(struct thread_info));
 129                 dump_stack();
 130         }
 131 }
 132 #else
 133 static inline void check_stack_overflow(void) {}
 134 #endif
 135
 136
 137 /*
 138  * do_IRQ handles all normal device IRQ's (the special
 139  * SMP cross-CPU interrupts have their own specific
 140  * handlers).
 141  */
 142 void __irq_entry do_IRQ(unsigned int irq)
 143 {
 144         irq_enter();
 145         check_stack_overflow();
 146         if (!smtc_handle_on_other_cpu(irq))
 147                 generic_handle_irq(irq);
 148         irq_exit();
 149 }
 150
 151 #ifdef CONFIG_MIPS_MT_SMTC_IRQAFF
 152 /*
 153  * To avoid inefficient and in some cases pathological re-checking of
 154  * IRQ affinity, we have this variant that skips the affinity check.
 155  */
 156
 157 void __irq_entry do_IRQ_no_affinity(unsigned int irq)
 158 {
 159         irq_enter();
 160         smtc_im_backstop(irq);
 161         generic_handle_irq(irq);
 162         irq_exit();
 163 }
 164
 165 #endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */