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         ACPI_FUNCTION_TRACE("acpi_system_read_event");
  52
  53         if (!chars_remaining) {
  54                 memset(&event, 0, sizeof(struct acpi_bus_event));
  55
  56                 if ((file->f_flags & O_NONBLOCK)
  57                     && (list_empty(&acpi_bus_event_list)))
  58                         return_VALUE(-EAGAIN);
  59
  60                 result = acpi_bus_receive_event(&event);
  61                 if (result) {
  62                         return_VALUE(-EIO);
  63                 }
  64
  65                 chars_remaining = sprintf(str, "%s %s %08x %08x\n",
  66                                           event.device_class ? event.
  67                                           device_class : "<unknown>",
  68                                           event.bus_id ? event.
  69                                           bus_id : "<unknown>", event.type,
  70                                           event.data);
  71                 ptr = str;
  72         }
  73
  74         if (chars_remaining < count) {
  75                 count = chars_remaining;
  76         }
  77
  78         if (copy_to_user(buffer, ptr, count))
  79                 return_VALUE(-EFAULT);
  80
  81         *ppos += count;
  82         chars_remaining -= count;
  83         ptr += count;
  84
  85         return_VALUE(count);
  86 }
  87
  88 static int acpi_system_close_event(struct inode *inode, struct file *file)
  89 {
  90         spin_lock_irq(&acpi_system_event_lock);
  91         event_is_open = 0;
  92         spin_unlock_irq(&acpi_system_event_lock);
  93         return 0;
  94 }
  95
  96 static unsigned int acpi_system_poll_event(struct file *file, poll_table * wait)
  97 {
  98         poll_wait(file, &acpi_bus_event_queue, wait);
  99         if (!list_empty(&acpi_bus_event_list))
 100                 return POLLIN | POLLRDNORM;
 101         return 0;
 102 }
 103
 104 static struct file_operations acpi_system_event_ops = {
 105         .open = acpi_system_open_event,
 106         .read = acpi_system_read_event,
 107         .release = acpi_system_close_event,
 108         .poll = acpi_system_poll_event,
 109 };
 110
 111 static int __init acpi_event_init(void)
 112 {
 113         struct proc_dir_entry *entry;
 114         int error = 0;
 115
 116         ACPI_FUNCTION_TRACE("acpi_event_init");
 117
 118         if (acpi_disabled)
 119                 return_VALUE(0);
 120
 121         /* 'event' [R] */
 122         entry = create_proc_entry("event", S_IRUSR, acpi_root_dir);
 123         if (entry)
 124                 entry->proc_fops = &acpi_system_event_ops;
 125         else {
 126                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 127                                   "Unable to create '%s' proc fs entry\n",
 128                                   "event"));
 129                 error = -EFAULT;
 130         }
 131         return_VALUE(error);
 132 }
 133
 134 subsys_initcall(acpi_event_init);