drivers/s390/char/ctrlchar.c

   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 static struct tty_struct *sysrq_tty;
  20
  21 static void
  22 ctrlchar_handle_sysrq(struct work_struct *work)
  23 {
  24         handle_sysrq(ctrlchar_sysrq_key, sysrq_tty);
  25 }
  26
  27 static DECLARE_WORK(ctrlchar_work, ctrlchar_handle_sysrq);
  28 #endif
  29
  30
  31 /**
  32  * Check for special chars at start of input.
  33  *
  34  * @param buf Console input buffer.
  35  * @param len Length of valid data in buffer.
  36  * @param tty The tty struct for this console.
  37  * @return CTRLCHAR_NONE, if nothing matched,
  38  *         CTRLCHAR_SYSRQ, if sysrq was encountered
  39  *         otherwise char to be inserted logically or'ed
  40  *         with CTRLCHAR_CTRL
  41  */
  42 unsigned int
  43 ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
  44 {
  45         if ((len < 2) || (len > 3))
  46                 return CTRLCHAR_NONE;
  47
  48         /* hat is 0xb1 in codepage 037 (US etc.) and thus */
  49         /* converted to 0x5e in ascii ('^') */
  50         if ((buf[0] != '^') && (buf[0] != '\252'))
  51                 return CTRLCHAR_NONE;
  52
  53 #ifdef CONFIG_MAGIC_SYSRQ
  54         /* racy */
  55         if (len == 3 && buf[1] == '-') {
  56                 ctrlchar_sysrq_key = buf[2];
  57                 sysrq_tty = tty;
  58                 schedule_work(&ctrlchar_work);
  59                 return CTRLCHAR_SYSRQ;
  60         }
  61 #endif
  62
  63         if (len != 2)
  64                 return CTRLCHAR_NONE;
  65
  66         switch (tolower(buf[1])) {
  67         case 'c':
  68                 return INTR_CHAR(tty) | CTRLCHAR_CTRL;
  69         case 'd':
  70                 return EOF_CHAR(tty)  | CTRLCHAR_CTRL;
  71         case 'z':
  72                 return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
  73         }
  74         return CTRLCHAR_NONE;
  75 }