[source navigation] [diff markup] [identifier search] [freetext search] [file search]

char_dev.c

Version: [1.0] [0.99.11] [0.99] [0.98] [0.97] [0.96a] [0.95] [0.12] [0.11] [0.01]
Architecture: [i386]

  1 /*
  2  *  linux/fs/char_dev.c
  3  *
  4  *  (C) 1991  Linus Torvalds
  5  */
  6 
  7 #include <errno.h>
  8 #include <sys/types.h>
  9 
 10 #include <linux/sched.h>
 11 #include <linux/kernel.h>
 12 
 13 #include <asm/segment.h>
 14 #include <asm/io.h>
 15 
 16 extern int tty_read(unsigned minor,char * buf,int count);
 17 extern int tty_write(unsigned minor,char * buf,int count);
 18 
 19 typedef (*crw_ptr)(int rw,unsigned minor,char * buf,int count,off_t * pos);
 20 
 21 static int rw_ttyx(int rw,unsigned minor,char * buf,int count,off_t * pos)
 22 {
 23         return ((rw==READ)?tty_read(minor,buf,count):
 24                 tty_write(minor,buf,count));
 25 }
 26 
 27 static int rw_tty(int rw,unsigned minor,char * buf,int count, off_t * pos)
 28 {
 29         if (current->tty<0)
 30                 return -EPERM;
 31         return rw_ttyx(rw,current->tty,buf,count,pos);
 32 }
 33 
 34 static int rw_ram(int rw,char * buf, int count, off_t *pos)
 35 {
 36         return -EIO;
 37 }
 38 
 39 static int rw_mem(int rw,char * buf, int count, off_t * pos)
 40 {
 41         return -EIO;
 42 }
 43 
 44 static int rw_kmem(int rw,char * buf, int count, off_t * pos)
 45 {
 46         return -EIO;
 47 }
 48 
 49 static int rw_port(int rw,char * buf, int count, off_t * pos)
 50 {
 51         int i=*pos;
 52 
 53         while (count-->0 && i<65536) {
 54                 if (rw==READ)
 55                         put_fs_byte(inb(i),buf++);
 56                 else
 57                         outb(get_fs_byte(buf++),i);
 58                 i++;
 59         }
 60         i -= *pos;
 61         *pos += i;
 62         return i;
 63 }
 64 
 65 static int rw_memory(int rw, unsigned minor, char * buf, int count, off_t * pos)
 66 {
 67         switch(minor) {
 68                 case 0:
 69                         return rw_ram(rw,buf,count,pos);
 70                 case 1:
 71                         return rw_mem(rw,buf,count,pos);
 72                 case 2:
 73                         return rw_kmem(rw,buf,count,pos);
 74                 case 3:
 75                         return (rw==READ)?0:count;      /* rw_null */
 76                 case 4:
 77                         return rw_port(rw,buf,count,pos);
 78                 default:
 79                         return -EIO;
 80         }
 81 }
 82 
 83 #define NRDEVS ((sizeof (crw_table))/(sizeof (crw_ptr)))
 84 
 85 static crw_ptr crw_table[]={
 86         NULL,           /* nodev */
 87         rw_memory,      /* /dev/mem etc */
 88         NULL,           /* /dev/fd */
 89         NULL,           /* /dev/hd */
 90         rw_ttyx,        /* /dev/ttyx */
 91         rw_tty,         /* /dev/tty */
 92         NULL,           /* /dev/lp */
 93         NULL};          /* unnamed pipes */
 94 
 95 int rw_char(int rw,int dev, char * buf, int count, off_t * pos)
 96 {
 97         crw_ptr call_addr;
 98 
 99         if (MAJOR(dev)>=NRDEVS)
100                 return -ENODEV;
101         if (!(call_addr=crw_table[MAJOR(dev)]))
102                 return -ENODEV;
103         return call_addr(rw,MINOR(dev),buf,count,pos);
104 }
105

[source navigation] [diff markup] [identifier search] [freetext search] [file search]

This page was automatically generated by the LXR engine.
Visit the LXR main site for more information.

Oldlinux Cross Reference Linux/fs/char_dev.c

Oldlinux Cross Reference
Linux/fs/char_dev.c