Blackfin arch: Add basic irq stack checking for Blackfin
[linux-2.6.git] / arch / blackfin / kernel / irqchip.c
1 /*
2  * File:         arch/blackfin/kernel/irqchip.c
3  * Based on:
4  * Author:
5  *
6  * Created:
7  * Description:  This file contains the simple DMA Implementation for Blackfin
8  *
9  * Modified:
10  *               Copyright 2004-2006 Analog Devices Inc.
11  *
12  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
13  *
14  * This program is free software; you can redistribute it and/or modify
15  * it under the terms of the GNU General Public License as published by
16  * the Free Software Foundation; either version 2 of the License, or
17  * (at your option) any later version.
18  *
19  * This program is distributed in the hope that it will be useful,
20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22  * GNU General Public License for more details.
23  *
24  * You should have received a copy of the GNU General Public License
25  * along with this program; if not, see the file COPYING, or write
26  * to the Free Software Foundation, Inc.,
27  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
28  */
29
30 #include <linux/kernel_stat.h>
31 #include <linux/module.h>
32 #include <linux/random.h>
33 #include <linux/seq_file.h>
34 #include <linux/kallsyms.h>
35 #include <linux/interrupt.h>
36 #include <linux/irq.h>
37 #include <asm/trace.h>
38
39 static atomic_t irq_err_count;
40 static spinlock_t irq_controller_lock;
41
42 /*
43  * Dummy mask/unmask handler
44  */
45 void dummy_mask_unmask_irq(unsigned int irq)
46 {
47 }
48
49 void ack_bad_irq(unsigned int irq)
50 {
51         atomic_inc(&irq_err_count);
52         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
53 }
54
55 static struct irq_chip bad_chip = {
56         .ack = dummy_mask_unmask_irq,
57         .mask = dummy_mask_unmask_irq,
58         .unmask = dummy_mask_unmask_irq,
59 };
60
61 static struct irq_desc bad_irq_desc = {
62         .status = IRQ_DISABLED,
63         .chip = &bad_chip,
64         .handle_irq = handle_bad_irq,
65         .depth = 1,
66         .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
67 #ifdef CONFIG_SMP
68         .affinity = CPU_MASK_ALL
69 #endif
70 };
71
72 int show_interrupts(struct seq_file *p, void *v)
73 {
74         int i = *(loff_t *) v, j;
75         struct irqaction *action;
76         unsigned long flags;
77
78         if (i < NR_IRQS) {
79                 spin_lock_irqsave(&irq_desc[i].lock, flags);
80                 action = irq_desc[i].action;
81                 if (!action)
82                         goto skip;
83                 seq_printf(p, "%3d: ", i);
84                 for_each_online_cpu(j)
85                         seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
86                 seq_printf(p, " %8s", irq_desc[i].chip->name);
87                 seq_printf(p, "  %s", action->name);
88                 for (action = action->next; action; action = action->next)
89                         seq_printf(p, "  %s", action->name);
90
91                 seq_putc(p, '\n');
92  skip:
93                 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
94         } else if (i == NR_IRQS)
95                 seq_printf(p, "Err: %10u\n",  atomic_read(&irq_err_count));
96         return 0;
97 }
98
99 /*
100  * do_IRQ handles all hardware IRQs.  Decoded IRQs should not
101  * come via this function.  Instead, they should provide their
102  * own 'handler'
103  */
104 #ifdef CONFIG_DO_IRQ_L1
105 __attribute__((l1_text))
106 #endif
107 asmlinkage void asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
108 {
109         struct pt_regs *old_regs;
110         struct irq_desc *desc = irq_desc + irq;
111         unsigned short pending, other_ints;
112
113         old_regs = set_irq_regs(regs);
114
115         /*
116          * Some hardware gives randomly wrong interrupts.  Rather
117          * than crashing, do something sensible.
118          */
119         if (irq >= NR_IRQS)
120                 desc = &bad_irq_desc;
121
122         irq_enter();
123 #ifdef CONFIG_DEBUG_STACKOVERFLOW
124         /* Debugging check for stack overflow: is there less than STACK_WARN free? */
125         {
126                 long sp;
127
128                 sp = __get_SP() & (THREAD_SIZE-1);
129
130                 if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
131                         dump_stack();
132                         printk(KERN_EMERG "%s: possible stack overflow while handling irq %i "
133                                         " only %ld bytes free\n",
134                                 __func__, irq, sp - sizeof(struct thread_info));
135                 }
136         }
137 #endif
138         generic_handle_irq(irq);
139
140         /* If we're the only interrupt running (ignoring IRQ15 which is for
141            syscalls), lower our priority to IRQ14 so that softirqs run at
142            that level.  If there's another, lower-level interrupt, irq_exit
143            will defer softirqs to that.  */
144         CSYNC();
145         pending = bfin_read_IPEND() & ~0x8000;
146         other_ints = pending & (pending - 1);
147         if (other_ints == 0)
148                 lower_to_irq14();
149         irq_exit();
150
151         set_irq_regs(old_regs);
152 }
153
154 void __init init_IRQ(void)
155 {
156         struct irq_desc *desc;
157         int irq;
158
159         spin_lock_init(&irq_controller_lock);
160         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++) {
161                 *desc = bad_irq_desc;
162         }
163
164         init_arch_irq();
165
166 #ifdef CONFIG_DEBUG_BFIN_HWTRACE_EXPAND
167         /* Now that evt_ivhw is set up, turn this on */
168         trace_buff_offset = 0;
169         bfin_write_TBUFCTL(BFIN_TRACE_ON);
170         printk(KERN_INFO "Hardware Trace expanded to %ik\n",
171           1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN);
172 #endif
173 }