drivers/acpi/event.c

   1 /*
   2  * event.c - exporting ACPI events via procfs
   3  *
   4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   6  *
   7  */
   8
   9 #include <linux/spinlock.h>
  10 #include <linux/proc_fs.h>
  11 #include <linux/init.h>
  12 #include <linux/poll.h>
  13 #include <acpi/acpi_drivers.h>
  14
  15 #define _COMPONENT              ACPI_SYSTEM_COMPONENT
  16 ACPI_MODULE_NAME("event")
  17
  18 /* Global vars for handling event proc entry */
  19 static DEFINE_SPINLOCK(acpi_system_event_lock);
  20 int event_is_open = 0;
  21 extern struct list_head acpi_bus_event_list;
  22 extern wait_queue_head_t acpi_bus_event_queue;
  23
  24 static int acpi_system_open_event(struct inode *inode, struct file *file)
  25 {
  26         spin_lock_irq(&acpi_system_event_lock);
  27
  28         if (event_is_open)
  29                 goto out_busy;
  30
  31         event_is_open = 1;
  32
  33         spin_unlock_irq(&acpi_system_event_lock);
  34         return 0;
  35
  36       out_busy:
  37         spin_unlock_irq(&acpi_system_event_lock);
  38         return -EBUSY;
  39 }
  40
  41 static ssize_t
  42 acpi_system_read_event(struct file *file, char __user * buffer, size_t count,
  43                        loff_t * ppos)
  44 {
  45         int result = 0;
  46         struct acpi_bus_event event;
  47         static char str[ACPI_MAX_STRING];
  48         static int chars_remaining = 0;
  49         static char *ptr;
  50
  51
  52         if (!chars_remaining) {
  53                 memset(&event, 0, sizeof(struct acpi_bus_event));
  54
  55                 if ((file->f_flags & O_NONBLOCK)
  56                     && (list_empty(&acpi_bus_event_list)))
  57                         return -EAGAIN;
  58
  59                 result = acpi_bus_receive_event(&event);
  60                 if (result)
  61                         return result;
  62
  63                 chars_remaining = sprintf(str, "%s %s %08x %08x\n",
  64                                           event.device_class ? event.
  65                                           device_class : "<unknown>",
  66                                           event.bus_id ? event.
  67                                           bus_id : "<unknown>", event.type,
  68                                           event.data);
  69                 ptr = str;
  70         }
  71
  72         if (chars_remaining < count) {
  73                 count = chars_remaining;
  74         }
  75
  76         if (copy_to_user(buffer, ptr, count))
  77                 return -EFAULT;
  78
  79         *ppos += count;
  80         chars_remaining -= count;
  81         ptr += count;
  82
  83         return count;
  84 }
  85
  86 static int acpi_system_close_event(struct inode *inode, struct file *file)
  87 {
  88         spin_lock_irq(&acpi_system_event_lock);
  89         event_is_open = 0;
  90         spin_unlock_irq(&acpi_system_event_lock);
  91         return 0;
  92 }
  93
  94 static unsigned int acpi_system_poll_event(struct file *file, poll_table * wait)
  95 {
  96         poll_wait(file, &acpi_bus_event_queue, wait);
  97         if (!list_empty(&acpi_bus_event_list))
  98                 return POLLIN | POLLRDNORM;
  99         return 0;
 100 }
 101
 102 static const struct file_operations acpi_system_event_ops = {
 103         .open = acpi_system_open_event,
 104         .read = acpi_system_read_event,
 105         .release = acpi_system_close_event,
 106         .poll = acpi_system_poll_event,
 107 };
 108
 109 static int __init acpi_event_init(void)
 110 {
 111         struct proc_dir_entry *entry;
 112         int error = 0;
 113
 114
 115         if (acpi_disabled)
 116                 return 0;
 117
 118         /* 'event' [R] */
 119         entry = create_proc_entry("event", S_IRUSR, acpi_root_dir);
 120         if (entry)
 121                 entry->proc_fops = &acpi_system_event_ops;
 122         else {
 123                 error = -ENODEV;
 124         }
 125         return error;
 126 }
 127
 128 subsys_initcall(acpi_event_init);