kernel/chardev.c

   1 #include "chardev.h"
   2 #include "stddef.h"
   3 #include "console.h"
   4
   5 static struct chardev *devs[MAX_CHARDEV_MAJOR + 1];
   6
   7 void chardev_init(void)
   8 {
   9     int i;
  10     for (i = 0; i <= MAX_CHARDEV_MAJOR; ++i){
  11         devs[i] = NULL;
  12     }
  13 }
  14
  15 ssize_t chardev_read(struct chardev *d, void *buf, size_t len)
  16 {
  17     return d->functab->read(d, buf, len);
  18 }
  19
  20 ssize_t chardev_write(struct chardev *d, const void *buf, size_t len)
  21 {
  22     return d->functab->write(d, buf, len);
  23 }
  24
  25 int chardev_register(struct chardev *cdev)
  26 {
  27     int major = cdev->major;
  28     if (devs[major]){
  29         devs[major]->prev = cdev;
  30     }
  31
  32     cdev->prev = NULL;
  33     cdev->next = devs[major];
  34     devs[major] = cdev;
  35     return 0;
  36 }
  37
  38 int chardev_unregister(struct chardev *cdev)
  39 {
  40     int major = cdev->major;
  41
  42     *(cdev->prev ? &cdev->prev->next : &devs[major])
  43       = cdev->next;
  44
  45     if (cdev->next){
  46         cdev->next->prev = cdev->prev;
  47     }
  48
  49     cdev->prev = cdev->next = NULL;
  50     return 0;
  51 }
  52
  53 struct chardev *chardev_get(int major, int minor)
  54 {
  55     struct chardev *cdev;
  56     cdev = devs[major];
  57     while (cdev && cdev->minor != minor){
  58         cdev = cdev->next;
  59     }
  60     return cdev;
  61 }