1 /*
2  *  drivers/s390/char/ctrlchar.c
3  *  Unified handling of special chars.
4  *
5  *    Copyright (C) 2001 IBM Deutschland Entwicklung GmbH, IBM Corporation
6  *    Author(s): Fritz Elfert <felfert@millenux.com> <elfert@de.ibm.com>
7  *
8  */
9 
10 #include <linux/stddef.h>
11 #include <asm/errno.h>
12 #include <linux/sysrq.h>
13 #include <linux/ctype.h>
14 
15 #include "ctrlchar.h"
16 
17 #ifdef CONFIG_MAGIC_SYSRQ
18 static int ctrlchar_sysrq_key;
19 
20 static void
ctrlchar_handle_sysrq(struct work_struct * work)21 ctrlchar_handle_sysrq(struct work_struct *work)
22 {
23 	handle_sysrq(ctrlchar_sysrq_key);
24 }
25 
26 static DECLARE_WORK(ctrlchar_work, ctrlchar_handle_sysrq);
27 #endif
28 
29 
30 /**
31  * Check for special chars at start of input.
32  *
33  * @param buf Console input buffer.
34  * @param len Length of valid data in buffer.
35  * @param tty The tty struct for this console.
36  * @return CTRLCHAR_NONE, if nothing matched,
37  *         CTRLCHAR_SYSRQ, if sysrq was encountered
38  *         otherwise char to be inserted logically or'ed
39  *         with CTRLCHAR_CTRL
40  */
41 unsigned int
ctrlchar_handle(const unsigned char * buf,int len,struct tty_struct * tty)42 ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
43 {
44 	if ((len < 2) || (len > 3))
45 		return CTRLCHAR_NONE;
46 
47 	/* hat is 0xb1 in codepage 037 (US etc.) and thus */
48 	/* converted to 0x5e in ascii ('^') */
49 	if ((buf[0] != '^') && (buf[0] != '\252'))
50 		return CTRLCHAR_NONE;
51 
52 #ifdef CONFIG_MAGIC_SYSRQ
53 	/* racy */
54 	if (len == 3 && buf[1] == '-') {
55 		ctrlchar_sysrq_key = buf[2];
56 		schedule_work(&ctrlchar_work);
57 		return CTRLCHAR_SYSRQ;
58 	}
59 #endif
60 
61 	if (len != 2)
62 		return CTRLCHAR_NONE;
63 
64 	switch (tolower(buf[1])) {
65 	case 'c':
66 		return INTR_CHAR(tty) | CTRLCHAR_CTRL;
67 	case 'd':
68 		return EOF_CHAR(tty)  | CTRLCHAR_CTRL;
69 	case 'z':
70 		return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
71 	}
72 	return CTRLCHAR_NONE;
73 }
74