arch/blackfin/kernel/early_printk.c

   1 /*
   2  * File:         arch/blackfin/kernel/early_printk.c
   3  * Based on:     arch/x86_64/kernel/early_printk.c
   4  * Author:       Robin Getz <rgetz@blackfin.uclinux.org
   5  *
   6  * Created:      14Aug2007
   7  * Description:  allow a console to be used for early printk
   8  *
   9  * Modified:
  10  *               Copyright 2004-2007 Analog Devices Inc.
  11  *
  12  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  */
  24
  25 #include <linux/kernel.h>
  26 #include <linux/init.h>
  27 #include <linux/serial_core.h>
  28 #include <linux/console.h>
  29 #include <linux/string.h>
  30 #include <asm/blackfin.h>
  31 #include <asm/irq_handler.h>
  32 #include <asm/early_printk.h>
  33
  34 #ifdef CONFIG_SERIAL_BFIN
  35 extern struct console *bfin_earlyserial_init(unsigned int port,
  36                                                 unsigned int cflag);
  37 #endif
  38 #ifdef CONFIG_BFIN_JTAG_COMM
  39 extern struct console *bfin_jc_early_init(void);
  40 #endif
  41
  42 static struct console *early_console;
  43
  44 /* Default console */
  45 #define DEFAULT_PORT 0
  46 #define DEFAULT_CFLAG CS8|B57600
  47
  48 /* Default console for early crashes */
  49 #define DEFAULT_EARLY_PORT "serial,uart0,57600"
  50
  51 #ifdef CONFIG_SERIAL_CORE
  52 /* What should get here is "0,57600" */
  53 static struct console * __init earlyserial_init(char *buf)
  54 {
  55         int baud, bit;
  56         char parity;
  57         unsigned int serial_port = DEFAULT_PORT;
  58         unsigned int cflag = DEFAULT_CFLAG;
  59
  60         serial_port = simple_strtoul(buf, &buf, 10);
  61         buf++;
  62
  63         cflag = 0;
  64         baud = simple_strtoul(buf, &buf, 10);
  65         switch (baud) {
  66         case 1200:
  67                 cflag |= B1200;
  68                 break;
  69         case 2400:
  70                 cflag |= B2400;
  71                 break;
  72         case 4800:
  73                 cflag |= B4800;
  74                 break;
  75         case 9600:
  76                 cflag |= B9600;
  77                 break;
  78         case 19200:
  79                 cflag |= B19200;
  80                 break;
  81         case 38400:
  82                 cflag |= B38400;
  83                 break;
  84         case 115200:
  85                 cflag |= B115200;
  86                 break;
  87         default:
  88                 cflag |= B57600;
  89         }
  90
  91         parity = buf[0];
  92         buf++;
  93         switch (parity) {
  94         case 'e':
  95                 cflag |= PARENB;
  96                 break;
  97         case 'o':
  98                 cflag |= PARODD;
  99                 break;
 100         }
 101
 102         bit = simple_strtoul(buf, &buf, 10);
 103         switch (bit) {
 104         case 5:
 105                 cflag |= CS5;
 106                 break;
 107         case 6:
 108                 cflag |= CS6;
 109                 break;
 110         case 7:
 111                 cflag |= CS7;
 112                 break;
 113         default:
 114                 cflag |= CS8;
 115         }
 116
 117 #ifdef CONFIG_SERIAL_BFIN
 118         return bfin_earlyserial_init(serial_port, cflag);
 119 #else
 120         return NULL;
 121 #endif
 122
 123 }
 124 #endif
 125
 126 int __init setup_early_printk(char *buf)
 127 {
 128
 129         /* Crashing in here would be really bad, so check both the var
 130            and the pointer before we start using it
 131          */
 132         if (!buf)
 133                 return 0;
 134
 135         if (!*buf)
 136                 return 0;
 137
 138         if (early_console != NULL)
 139                 return 0;
 140
 141 #ifdef CONFIG_SERIAL_BFIN
 142         /* Check for Blackfin Serial */
 143         if (!strncmp(buf, "serial,uart", 11)) {
 144                 buf += 11;
 145                 early_console = earlyserial_init(buf);
 146         }
 147 #endif
 148
 149 #ifdef CONFIG_BFIN_JTAG_COMM
 150         /* Check for Blackfin JTAG */
 151         if (!strncmp(buf, "jtag", 4)) {
 152                 buf += 4;
 153                 early_console = bfin_jc_early_init();
 154         }
 155 #endif
 156
 157 #ifdef CONFIG_FB
 158                 /* TODO: add framebuffer console support */
 159 #endif
 160
 161         if (likely(early_console)) {
 162                 early_console->flags |= CON_BOOT;
 163
 164                 register_console(early_console);
 165                 printk(KERN_INFO "early printk enabled on %s%d\n",
 166                         early_console->name,
 167                         early_console->index);
 168         }
 169
 170         return 0;
 171 }
 172
 173 /*
 174  * Set up a temporary Event Vector Table, so if something bad happens before
 175  * the kernel is fully started, it doesn't vector off into somewhere we don't
 176  * know
 177  */
 178
 179 asmlinkage void __init init_early_exception_vectors(void)
 180 {
 181         u32 evt;
 182         SSYNC();
 183
 184         /* cannot program in software:
 185          * evt0 - emulation (jtag)
 186          * evt1 - reset
 187          */
 188         for (evt = EVT2; evt <= EVT15; evt += 4)
 189                 bfin_write32(evt, early_trap);
 190         CSYNC();
 191
 192         /* Set all the return from interrupt, exception, NMI to a known place
 193          * so if we do a RETI, RETX or RETN by mistake - we go somewhere known
 194          * Note - don't change RETS - we are in a subroutine, or
 195          * RETE - since it might screw up if emulator is attached
 196          */
 197         asm("\tRETI = %0; RETX = %0; RETN = %0;\n"
 198                 : : "p"(early_trap));
 199
 200 }
 201
 202 asmlinkage void __init early_trap_c(struct pt_regs *fp, void *retaddr)
 203 {
 204         /* This can happen before the uart is initialized, so initialize
 205          * the UART now (but only if we are running on the processor we think
 206          * we are compiled for - otherwise we write to MMRs that don't exist,
 207          * and cause other problems. Nothing comes out the UART, but it does
 208          * end up in the __buf_log.
 209          */
 210         if (likely(early_console == NULL) && CPUID == bfin_cpuid())
 211                 setup_early_printk(DEFAULT_EARLY_PORT);
 212
 213         printk(KERN_EMERG "Early panic\n");
 214         dump_bfin_mem(fp);
 215         show_regs(fp);
 216         dump_bfin_trace_buffer();
 217
 218         panic("Died early");
 219 }
 220
 221 early_param("earlyprintk", setup_early_printk);