add directory kernel

kernel/0.95/linux-0.95/fs/char_dev.c

@@ -0,0 +1,136 @@
+/*
+ *  linux/fs/char_dev.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#include <errno.h>
+#include <sys/types.h>
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+
+#include <asm/segment.h>
+#include <asm/io.h>
+
+extern int tty_read(unsigned minor,char * buf,int count,unsigned short flags);
+extern int tty_write(unsigned minor,char * buf,int count);
+
+typedef (*crw_ptr)(int,unsigned,char *,int,off_t *,unsigned short);
+
+static int rw_ttyx(int rw,unsigned minor,char * buf,int count,off_t * pos, unsigned short flags)
+{
+	return ((rw==READ)?tty_read(minor,buf,count,flags):
+		tty_write(minor,buf,count));
+}
+
+static int rw_tty(int rw,unsigned minor,char * buf,int count, off_t * pos, unsigned short flags)
+{
+	if (current->tty<0)
+		return -EPERM;
+	return rw_ttyx(rw,current->tty,buf,count,pos,flags);
+}
+
+static int rw_ram(int rw,char * buf, int count, off_t *pos)
+{
+	return -EIO;
+}
+
+static int rw_mem(int rw,char * buf, int count, off_t * pos)
+{
+	return -EIO;
+}
+
+static int rw_kmem(int rw,char * buf, int count, off_t * pos)
+{
+	/* kmem by Damiano */
+	int i = *pos;	/* Current position where to read	*/
+
+	/* i can go from 0 to LOW_MEM (See include/linux/mm.h	*/
+	/* I am not shure about it but it doesn't mem fault :-)	*/
+	while ( (count-- > 0)  && (i <LOW_MEM) ) {
+		if (rw==READ)
+			put_fs_byte( *(char *)i ,buf++);
+		else
+			return (-EIO);
+		i++;
+	}
+	i -= *pos;		/* Count how many read or write		*/
+	*pos += i;		/* Update position			*/
+	return (i);		/* Return number read			*/
+}
+
+static int rw_port(int rw,char * buf, int count, off_t * pos)
+{
+	int i=*pos;
+
+	while (count-->0 && i<65536) {
+		if (rw==READ)
+			put_fs_byte(inb(i),buf++);
+		else
+			outb(get_fs_byte(buf++),i);
+		i++;
+	}
+	i -= *pos;
+	*pos += i;
+	return i;
+}
+
+static int rw_memory(int rw, unsigned minor, char * buf, int count,
+	off_t * pos, unsigned short flags)
+{
+	switch(minor) {
+		case 0:
+			return rw_ram(rw,buf,count,pos);
+		case 1:
+			return rw_mem(rw,buf,count,pos);
+		case 2:
+			return rw_kmem(rw,buf,count,pos);
+		case 3:
+			return (rw==READ)?0:count;	/* rw_null */
+		case 4:
+			return rw_port(rw,buf,count,pos);
+		default:
+			return -EIO;
+	}
+}
+
+#define NRDEVS ((sizeof (crw_table))/(sizeof (crw_ptr)))
+
+static crw_ptr crw_table[]={
+	NULL,		/* nodev */
+	rw_memory,	/* /dev/mem etc */
+	NULL,		/* /dev/fd */
+	NULL,		/* /dev/hd */
+	rw_ttyx,	/* /dev/ttyx */
+	rw_tty,		/* /dev/tty */
+	NULL,		/* /dev/lp */
+	NULL};		/* unnamed pipes */
+
+int char_read(struct inode * inode, struct file * filp, char * buf, int count)
+{
+	unsigned int major,minor;
+	crw_ptr call_addr;
+
+	major = MAJOR(inode->i_rdev);
+	minor = MINOR(inode->i_rdev);
+	if (major >= NRDEVS)
+		return -ENODEV;
+	if (!(call_addr = crw_table[major]))
+		return -ENODEV;
+	return call_addr(READ,minor,buf,count,&filp->f_pos,filp->f_flags);
+}
+
+int char_write(struct inode * inode, struct file * filp, char * buf, int count)
+{
+	unsigned int major,minor;
+	crw_ptr call_addr;
+
+	major = MAJOR(inode->i_rdev);
+	minor = MINOR(inode->i_rdev);
+	if (major >= NRDEVS)
+		return -ENODEV;
+	if (!(call_addr=crw_table[major]))
+		return -ENODEV;
+	return call_addr(WRITE,minor,buf,count,&filp->f_pos,filp->f_flags);
+}