arch/parisc/kernel/pdc_cons.c

   1 /*
   2  *    PDC Console support - ie use firmware to dump text via boot console
   3  *
   4  *    Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
   5  *    Copyright (C) 2000 Martin K Petersen <mkp at mkp.net>
   6  *    Copyright (C) 2000 John Marvin <jsm at parisc-linux.org>
   7  *    Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
   8  *    Copyright (C) 2000 Philipp Rumpf <prumpf with tux.org>
   9  *    Copyright (C) 2000 Michael Ang <mang with subcarrier.org>
  10  *    Copyright (C) 2000 Grant Grundler <grundler with parisc-linux.org>
  11  *    Copyright (C) 2001-2002 Ryan Bradetich <rbrad at parisc-linux.org>
  12  *    Copyright (C) 2001 Helge Deller <deller at parisc-linux.org>
  13  *    Copyright (C) 2001 Thomas Bogendoerfer <tsbogend at parisc-linux.org>
  14  *    Copyright (C) 2002 Randolph Chung <tausq with parisc-linux.org>
  15  *
  16  *
  17  *    This program is free software; you can redistribute it and/or modify
  18  *    it under the terms of the GNU General Public License as published by
  19  *    the Free Software Foundation; either version 2 of the License, or
  20  *    (at your option) any later version.
  21  *
  22  *    This program is distributed in the hope that it will be useful,
  23  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25  *    GNU General Public License for more details.
  26  *
  27  *    You should have received a copy of the GNU General Public License
  28  *    along with this program; if not, write to the Free Software
  29  *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  30  */
  31
  32 /*
  33  *  The PDC console is a simple console, which can be used for debugging
  34  *  boot related problems on HP PA-RISC machines.
  35  *
  36  *  This code uses the ROM (=PDC) based functions to read and write characters
  37  *  from and to PDC's boot path.
  38  *  Since all character read from that path must be polled, this code never
  39  *  can or will be a fully functional linux console.
  40  */
  41
  42 /* Define EARLY_BOOTUP_DEBUG to debug kernel related boot problems.
  43  * On production kernels EARLY_BOOTUP_DEBUG should be undefined. */
  44 #define EARLY_BOOTUP_DEBUG
  45
  46
  47 #include <linux/kernel.h>
  48 #include <linux/console.h>
  49 #include <linux/string.h>
  50 #include <linux/init.h>
  51 #include <linux/major.h>
  52 #include <linux/tty.h>
  53 #include <asm/pdc.h>            /* for iodc_call() proto and friends */
  54
  55 static DEFINE_SPINLOCK(pdc_console_lock);
  56
  57 static void pdc_console_write(struct console *co, const char *s, unsigned count)
  58 {
  59         int i = 0;
  60         unsigned long flags;
  61
  62         spin_lock_irqsave(&pdc_console_lock, flags);
  63         do {
  64                 i += pdc_iodc_print(s + i, count - i);
  65         } while (i < count);
  66         spin_unlock_irqrestore(&pdc_console_lock, flags);
  67 }
  68
  69 int pdc_console_poll_key(struct console *co)
  70 {
  71         int c;
  72         unsigned long flags;
  73
  74         spin_lock_irqsave(&pdc_console_lock, flags);
  75         c = pdc_iodc_getc();
  76         spin_unlock_irqrestore(&pdc_console_lock, flags);
  77
  78         return c;
  79 }
  80
  81 static int pdc_console_setup(struct console *co, char *options)
  82 {
  83         return 0;
  84 }
  85
  86 #if defined(CONFIG_PDC_CONSOLE)
  87 #include <linux/vt_kern.h>
  88
  89 static struct tty_driver * pdc_console_device (struct console *c, int *index)
  90 {
  91         extern struct tty_driver console_driver;
  92         *index = c->index ? c->index-1 : fg_console;
  93         return &console_driver;
  94 }
  95 #else
  96 #define pdc_console_device NULL
  97 #endif
  98
  99 static struct console pdc_cons = {
 100         .name =         "ttyB",
 101         .write =        pdc_console_write,
 102         .device =       pdc_console_device,
 103         .setup =        pdc_console_setup,
 104         .flags =        CON_BOOT | CON_PRINTBUFFER | CON_ENABLED,
 105         .index =        -1,
 106 };
 107
 108 static int pdc_console_initialized;
 109
 110 static void pdc_console_init_force(void)
 111 {
 112         if (pdc_console_initialized)
 113                 return;
 114         ++pdc_console_initialized;
 115
 116         /* If the console is duplex then copy the COUT parameters to CIN. */
 117         if (PAGE0->mem_cons.cl_class == CL_DUPLEX)
 118                 memcpy(&PAGE0->mem_kbd, &PAGE0->mem_cons, sizeof(PAGE0->mem_cons));
 119
 120         /* register the pdc console */
 121         register_console(&pdc_cons);
 122 }
 123
 124 void __init pdc_console_init(void)
 125 {
 126 #if defined(EARLY_BOOTUP_DEBUG) || defined(CONFIG_PDC_CONSOLE)
 127         pdc_console_init_force();
 128 #endif
 129 #ifdef EARLY_BOOTUP_DEBUG
 130         printk(KERN_INFO "Initialized PDC Console for debugging.\n");
 131 #endif
 132 }
 133
 134
 135 /*
 136  * Used for emergencies. Currently only used if an HPMC occurs. If an
 137  * HPMC occurs, it is possible that the current console may not be
 138  * properly initialised after the PDC IO reset. This routine unregisters
 139  * all of the current consoles, reinitializes the pdc console and
 140  * registers it.
 141  */
 142
 143 void pdc_console_restart(void)
 144 {
 145         struct console *console;
 146
 147         if (pdc_console_initialized)
 148                 return;
 149
 150         /* If we've already seen the output, don't bother to print it again */
 151         if (console_drivers != NULL)
 152                 pdc_cons.flags &= ~CON_PRINTBUFFER;
 153
 154         while ((console = console_drivers) != NULL)
 155                 unregister_console(console_drivers);
 156
 157         /* force registering the pdc console */
 158         pdc_console_init_force();
 159 }