xref: /openbmc/linux/arch/mips/kernel/irq.c (revision 9c1f8594)
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 */
167