kernel/irq/proc.c

   1 /*
   2  * linux/kernel/irq/proc.c
   3  *
   4  * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
   5  *
   6  * This file contains the /proc/irq/ handling code.
   7  */
   8
   9 #include <linux/irq.h>
  10 #include <linux/proc_fs.h>
  11 #include <linux/interrupt.h>
  12
  13 #include "internals.h"
  14
  15 static struct proc_dir_entry *root_irq_dir;
  16
  17 #ifdef CONFIG_SMP
  18
  19 static int irq_affinity_read_proc(char *page, char **start, off_t off,
  20                                   int count, int *eof, void *data)
  21 {
  22         int len = cpumask_scnprintf(page, count, irq_desc[(long)data].affinity);
  23
  24         if (count - len < 2)
  25                 return -EINVAL;
  26         len += sprintf(page + len, "\n");
  27         return len;
  28 }
  29
  30 int no_irq_affinity;
  31 static int irq_affinity_write_proc(struct file *file, const char __user *buffer,
  32                                    unsigned long count, void *data)
  33 {
  34         unsigned int irq = (int)(long)data, full_count = count, err;
  35         cpumask_t new_value, tmp;
  36
  37         if (!irq_desc[irq].chip->set_affinity || no_irq_affinity ||
  38             irq_balancing_disabled(irq))
  39                 return -EIO;
  40
  41         err = cpumask_parse_user(buffer, count, new_value);
  42         if (err)
  43                 return err;
  44
  45         /*
  46          * Do not allow disabling IRQs completely - it's a too easy
  47          * way to make the system unusable accidentally :-) At least
  48          * one online CPU still has to be targeted.
  49          */
  50         cpus_and(tmp, new_value, cpu_online_map);
  51         if (cpus_empty(tmp))
  52                 /* Special case for empty set - allow the architecture
  53                    code to set default SMP affinity. */
  54                 return select_smp_affinity(irq) ? -EINVAL : full_count;
  55
  56         irq_set_affinity(irq, new_value);
  57
  58         return full_count;
  59 }
  60
  61 #endif
  62
  63 #define MAX_NAMELEN 128
  64
  65 static int name_unique(unsigned int irq, struct irqaction *new_action)
  66 {
  67         struct irq_desc *desc = irq_desc + irq;
  68         struct irqaction *action;
  69         unsigned long flags;
  70         int ret = 1;
  71
  72         spin_lock_irqsave(&desc->lock, flags);
  73         for (action = desc->action ; action; action = action->next) {
  74                 if ((action != new_action) && action->name &&
  75                                 !strcmp(new_action->name, action->name)) {
  76                         ret = 0;
  77                         break;
  78                 }
  79         }
  80         spin_unlock_irqrestore(&desc->lock, flags);
  81         return ret;
  82 }
  83
  84 void register_handler_proc(unsigned int irq, struct irqaction *action)
  85 {
  86         char name [MAX_NAMELEN];
  87
  88         if (!irq_desc[irq].dir || action->dir || !action->name ||
  89                                         !name_unique(irq, action))
  90                 return;
  91
  92         memset(name, 0, MAX_NAMELEN);
  93         snprintf(name, MAX_NAMELEN, "%s", action->name);
  94
  95         /* create /proc/irq/1234/handler/ */
  96         action->dir = proc_mkdir(name, irq_desc[irq].dir);
  97 }
  98
  99 #undef MAX_NAMELEN
 100
 101 #define MAX_NAMELEN 10
 102
 103 void register_irq_proc(unsigned int irq)
 104 {
 105         char name [MAX_NAMELEN];
 106
 107         if (!root_irq_dir ||
 108                 (irq_desc[irq].chip == &no_irq_chip) ||
 109                         irq_desc[irq].dir)
 110                 return;
 111
 112         memset(name, 0, MAX_NAMELEN);
 113         sprintf(name, "%d", irq);
 114
 115         /* create /proc/irq/1234 */
 116         irq_desc[irq].dir = proc_mkdir(name, root_irq_dir);
 117
 118 #ifdef CONFIG_SMP
 119         {
 120                 struct proc_dir_entry *entry;
 121
 122                 /* create /proc/irq/<irq>/smp_affinity */
 123                 entry = create_proc_entry("smp_affinity", 0600, irq_desc[irq].dir);
 124
 125                 if (entry) {
 126                         entry->data = (void *)(long)irq;
 127                         entry->read_proc = irq_affinity_read_proc;
 128                         entry->write_proc = irq_affinity_write_proc;
 129                 }
 130         }
 131 #endif
 132 }
 133
 134 #undef MAX_NAMELEN
 135
 136 void unregister_handler_proc(unsigned int irq, struct irqaction *action)
 137 {
 138         if (action->dir)
 139                 remove_proc_entry(action->dir->name, irq_desc[irq].dir);
 140 }
 141
 142 void init_irq_proc(void)
 143 {
 144         int i;
 145
 146         /* create /proc/irq */
 147         root_irq_dir = proc_mkdir("irq", NULL);
 148         if (!root_irq_dir)
 149                 return;
 150
 151         /*
 152          * Create entries for all existing IRQs.
 153          */
 154         for (i = 0; i < NR_IRQS; i++)
 155                 register_irq_proc(i);
 156 }
 157