release/src-rt-6.x.4708/linux/linux-2.6.36/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
  20 static void
  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
  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 }