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
  70         for (action = desc->action ; action; action = action->next)
  71                 if ((action != new_action) && action->name &&
  72                                 !strcmp(new_action->name, action->name))
  73                         return 0;
  74         return 1;
  75 }
  76
  77 void register_handler_proc(unsigned int irq, struct irqaction *action)
  78 {
  79         char name [MAX_NAMELEN];
  80
  81         if (!irq_desc[irq].dir || action->dir || !action->name ||
  82                                         !name_unique(irq, action))
  83                 return;
  84
  85         memset(name, 0, MAX_NAMELEN);
  86         snprintf(name, MAX_NAMELEN, "%s", action->name);
  87
  88         /* create /proc/irq/1234/handler/ */
  89         action->dir = proc_mkdir(name, irq_desc[irq].dir);
  90 }
  91
  92 #undef MAX_NAMELEN
  93
  94 #define MAX_NAMELEN 10
  95
  96 void register_irq_proc(unsigned int irq)
  97 {
  98         char name [MAX_NAMELEN];
  99
 100         if (!root_irq_dir ||
 101                 (irq_desc[irq].chip == &no_irq_chip) ||
 102                         irq_desc[irq].dir)
 103                 return;
 104
 105         memset(name, 0, MAX_NAMELEN);
 106         sprintf(name, "%d", irq);
 107
 108         /* create /proc/irq/1234 */
 109         irq_desc[irq].dir = proc_mkdir(name, root_irq_dir);
 110
 111 #ifdef CONFIG_SMP
 112         {
 113                 struct proc_dir_entry *entry;
 114
 115                 /* create /proc/irq/<irq>/smp_affinity */
 116                 entry = create_proc_entry("smp_affinity", 0600, irq_desc[irq].dir);
 117
 118                 if (entry) {
 119                         entry->data = (void *)(long)irq;
 120                         entry->read_proc = irq_affinity_read_proc;
 121                         entry->write_proc = irq_affinity_write_proc;
 122                 }
 123         }
 124 #endif
 125 }
 126
 127 #undef MAX_NAMELEN
 128
 129 void unregister_handler_proc(unsigned int irq, struct irqaction *action)
 130 {
 131         if (action->dir)
 132                 remove_proc_entry(action->dir->name, irq_desc[irq].dir);
 133 }
 134
 135 void init_irq_proc(void)
 136 {
 137         int i;
 138
 139         /* create /proc/irq */
 140         root_irq_dir = proc_mkdir("irq", NULL);
 141         if (!root_irq_dir)
 142                 return;
 143
 144         /*
 145          * Create entries for all existing IRQs.
 146          */
 147         for (i = 0; i < NR_IRQS; i++)
 148                 register_irq_proc(i);
 149 }
 150