Linux Kernel  3.7.1
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irq.c
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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  */
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 {
66  clear_bit(irq, irq_map);
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 
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 
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 */