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