arch/powerpc/kernel/udbg.c

   1 /*
   2  * polling mode stateless debugging stuff, originally for NS16550 Serial Ports
   3  *
   4  * c 2001 PPC 64 Team, IBM Corp
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <stdarg.h>
  13 #include <linux/config.h>
  14 #include <linux/types.h>
  15 #include <linux/sched.h>
  16 #include <linux/console.h>
  17 #include <asm/processor.h>
  18
  19 void (*udbg_putc)(char c);
  20 int (*udbg_getc)(void);
  21 int (*udbg_getc_poll)(void);
  22
  23 /* udbg library, used by xmon et al */
  24 void udbg_puts(const char *s)
  25 {
  26         if (udbg_putc) {
  27                 char c;
  28
  29                 if (s && *s != '\0') {
  30                         while ((c = *s++) != '\0')
  31                                 udbg_putc(c);
  32                 }
  33         }
  34 #if 0
  35         else {
  36                 printk("%s", s);
  37         }
  38 #endif
  39 }
  40
  41 int udbg_write(const char *s, int n)
  42 {
  43         int remain = n;
  44         char c;
  45
  46         if (!udbg_putc)
  47                 return 0;
  48
  49         if (s && *s != '\0') {
  50                 while (((c = *s++) != '\0') && (remain-- > 0)) {
  51                         udbg_putc(c);
  52                 }
  53         }
  54
  55         return n - remain;
  56 }
  57
  58 int udbg_read(char *buf, int buflen)
  59 {
  60         char *p = buf;
  61         int i, c;
  62
  63         if (!udbg_getc)
  64                 return 0;
  65
  66         for (i = 0; i < buflen; ++i) {
  67                 do {
  68                         c = udbg_getc();
  69                         if (c == -1 && i == 0)
  70                                 return -1;
  71
  72                 } while (c == 0x11 || c == 0x13);
  73                 if (c == 0 || c == -1)
  74                         break;
  75                 *p++ = c;
  76         }
  77
  78         return i;
  79 }
  80
  81 #define UDBG_BUFSIZE 256
  82 void udbg_printf(const char *fmt, ...)
  83 {
  84         char buf[UDBG_BUFSIZE];
  85         va_list args;
  86
  87         va_start(args, fmt);
  88         vsnprintf(buf, UDBG_BUFSIZE, fmt, args);
  89         udbg_puts(buf);
  90         va_end(args);
  91 }
  92
  93 /*
  94  * Early boot console based on udbg
  95  */
  96 static void udbg_console_write(struct console *con, const char *s,
  97                 unsigned int n)
  98 {
  99         udbg_write(s, n);
 100 }
 101
 102 static struct console udbg_console = {
 103         .name   = "udbg",
 104         .write  = udbg_console_write,
 105         .flags  = CON_PRINTBUFFER | CON_ENABLED,
 106         .index  = -1,
 107 };
 108
 109 static int early_console_initialized;
 110
 111 void __init disable_early_printk(void)
 112 {
 113         if (!early_console_initialized)
 114                 return;
 115         unregister_console(&udbg_console);
 116         early_console_initialized = 0;
 117 }
 118
 119 /* called by setup_system */
 120 void register_early_udbg_console(void)
 121 {
 122         if (early_console_initialized)
 123                 return;
 124         early_console_initialized = 1;
 125         register_console(&udbg_console);
 126 }
 127
 128 #if 0   /* if you want to use this as a regular output console */
 129 console_initcall(register_udbg_console);
 130 #endif