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 #ifndef is_affinity_mask_valid
  31 #define is_affinity_mask_valid(val) 1
  32 #endif
  33
  34 int no_irq_affinity;
  35 static int irq_affinity_write_proc(struct file *file, const char __user *buffer,
  36                                    unsigned long count, void *data)
  37 {
  38         unsigned int irq = (int)(long)data, full_count = count, err;
  39         cpumask_t new_value, tmp;
  40
  41         if (!irq_desc[irq].chip->set_affinity || no_irq_affinity ||
  42             irq_balancing_disabled(irq))
  43                 return -EIO;
  44
  45         err = cpumask_parse_user(buffer, count, new_value);
  46         if (err)
  47                 return err;
  48
  49         if (!is_affinity_mask_valid(new_value))
  50                 return -EINVAL;
  51
  52         /*
  53          * Do not allow disabling IRQs completely - it's a too easy
  54          * way to make the system unusable accidentally :-) At least
  55          * one online CPU still has to be targeted.
  56          */
  57         cpus_and(tmp, new_value, cpu_online_map);
  58         if (cpus_empty(tmp))
  59                 /* Special case for empty set - allow the architecture
  60                    code to set default SMP affinity. */
  61                 return select_smp_affinity(irq) ? -EINVAL : full_count;
  62
  63         irq_set_affinity(irq, new_value);
  64
  65         return full_count;
  66 }
  67
  68 #endif
  69
  70 #define MAX_NAMELEN 128
  71
  72 static int name_unique(unsigned int irq, struct irqaction *new_action)
  73 {
  74         struct irq_desc *desc = irq_desc + irq;
  75         struct irqaction *action;
  76         unsigned long flags;
  77         int ret = 1;
  78
  79         spin_lock_irqsave(&desc->lock, flags);
  80         for (action = desc->action ; action; action = action->next) {
  81                 if ((action != new_action) && action->name &&
  82                                 !strcmp(new_action->name, action->name)) {
  83                         ret = 0;
  84                         break;
  85                 }
  86         }
  87         spin_unlock_irqrestore(&desc->lock, flags);
  88         return ret;
  89 }
  90
  91 void register_handler_proc(unsigned int irq, struct irqaction *action)
  92 {
  93         char name [MAX_NAMELEN];
  94
  95         if (!irq_desc[irq].dir || action->dir || !action->name ||
  96                                         !name_unique(irq, action))
  97                 return;
  98
  99         memset(name, 0, MAX_NAMELEN);
 100         snprintf(name, MAX_NAMELEN, "%s", action->name);
 101
 102         /* create /proc/irq/1234/handler/ */
 103         action->dir = proc_mkdir(name, irq_desc[irq].dir);
 104 }
 105
 106 #undef MAX_NAMELEN
 107
 108 #define MAX_NAMELEN 10
 109
 110 void register_irq_proc(unsigned int irq)
 111 {
 112         char name [MAX_NAMELEN];
 113
 114         if (!root_irq_dir ||
 115                 (irq_desc[irq].chip == &no_irq_chip) ||
 116                         irq_desc[irq].dir)
 117                 return;
 118
 119         memset(name, 0, MAX_NAMELEN);
 120         sprintf(name, "%d", irq);
 121
 122         /* create /proc/irq/1234 */
 123         irq_desc[irq].dir = proc_mkdir(name, root_irq_dir);
 124
 125 #ifdef CONFIG_SMP
 126         {
 127                 struct proc_dir_entry *entry;
 128
 129                 /* create /proc/irq/<irq>/smp_affinity */
 130                 entry = create_proc_entry("smp_affinity", 0600, irq_desc[irq].dir);
 131
 132                 if (entry) {
 133                         entry->data = (void *)(long)irq;
 134                         entry->read_proc = irq_affinity_read_proc;
 135                         entry->write_proc = irq_affinity_write_proc;
 136                 }
 137         }
 138 #endif
 139 }
 140
 141 #undef MAX_NAMELEN
 142
 143 void unregister_handler_proc(unsigned int irq, struct irqaction *action)
 144 {
 145         if (action->dir)
 146                 remove_proc_entry(action->dir->name, irq_desc[irq].dir);
 147 }
 148
 149 void init_irq_proc(void)
 150 {
 151         int i;
 152
 153         /* create /proc/irq */
 154         root_irq_dir = proc_mkdir("irq", NULL);
 155         if (!root_irq_dir)
 156                 return;
 157
 158         /*
 159          * Create entries for all existing IRQs.
 160          */
 161         for (i = 0; i < NR_IRQS; i++)
 162                 register_irq_proc(i);
 163 }
 164