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