xref: /openbmc/linux/arch/um/drivers/null.c (revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2)
1 /*
2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
3  * Licensed under the GPL
4  */
5 
6 #include <stdlib.h>
7 #include <errno.h>
8 #include "chan_user.h"
9 #include "os.h"
10 
11 static int null_chan;
12 
13 static void *null_init(char *str, int device, struct chan_opts *opts)
14 {
15 	return(&null_chan);
16 }
17 
18 static int null_open(int input, int output, int primary, void *d,
19 		     char **dev_out)
20 {
21 	*dev_out = NULL;
22 	return(os_open_file(DEV_NULL, of_rdwr(OPENFLAGS()), 0));
23 }
24 
25 static int null_read(int fd, char *c_out, void *unused)
26 {
27 	return(-ENODEV);
28 }
29 
30 static void null_free(void *data)
31 {
32 }
33 
34 struct chan_ops null_ops = {
35 	.type		= "null",
36 	.init		= null_init,
37 	.open		= null_open,
38 	.close		= generic_close,
39 	.read		= null_read,
40 	.write		= generic_write,
41 	.console_write	= generic_console_write,
42 	.window_size	= generic_window_size,
43 	.free		= null_free,
44 	.winch		= 0,
45 };
46 
47 /*
48  * Overrides for Emacs so that we follow Linus's tabbing style.
49  * Emacs will notice this stuff at the end of the file and automatically
50  * adjust the settings for this buffer only.  This must remain at the end
51  * of the file.
52  * ---------------------------------------------------------------------------
53  * Local variables:
54  * c-file-style: "linux"
55  * End:
56  */
57