arch/blackfin/kernel/early_printk.c

   1 /*
   2  * allow a console to be used for early printk
   3  * derived from arch/x86/kernel/early_printk.c
   4  *
   5  * Copyright 2007-2009 Analog Devices Inc.
   6  *
   7  * Licensed under the GPL-2
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/init.h>
  12 #include <linux/serial_core.h>
  13 #include <linux/console.h>
  14 #include <linux/string.h>
  15 #include <linux/reboot.h>
  16 #include <asm/blackfin.h>
  17 #include <asm/irq_handler.h>
  18 #include <asm/early_printk.h>
  19
  20 #ifdef CONFIG_SERIAL_BFIN
  21 extern struct console *bfin_earlyserial_init(unsigned int port,
  22                                                 unsigned int cflag);
  23 #endif
  24 #ifdef CONFIG_BFIN_JTAG_COMM
  25 extern struct console *bfin_jc_early_init(void);
  26 #endif
  27
  28 /* Default console */
  29 #define DEFAULT_PORT 0
  30 #define DEFAULT_CFLAG CS8|B57600
  31
  32 /* Default console for early crashes */
  33 #define DEFAULT_EARLY_PORT "serial,uart0,57600"
  34
  35 #ifdef CONFIG_SERIAL_CORE
  36 /* What should get here is "0,57600" */
  37 static struct console * __init earlyserial_init(char *buf)
  38 {
  39         int baud, bit;
  40         char parity;
  41         unsigned int serial_port = DEFAULT_PORT;
  42         unsigned int cflag = DEFAULT_CFLAG;
  43
  44         serial_port = simple_strtoul(buf, &buf, 10);
  45         buf++;
  46
  47         cflag = 0;
  48         baud = simple_strtoul(buf, &buf, 10);
  49         switch (baud) {
  50         case 1200:
  51                 cflag |= B1200;
  52                 break;
  53         case 2400:
  54                 cflag |= B2400;
  55                 break;
  56         case 4800:
  57                 cflag |= B4800;
  58                 break;
  59         case 9600:
  60                 cflag |= B9600;
  61                 break;
  62         case 19200:
  63                 cflag |= B19200;
  64                 break;
  65         case 38400:
  66                 cflag |= B38400;
  67                 break;
  68         case 115200:
  69                 cflag |= B115200;
  70                 break;
  71         default:
  72                 cflag |= B57600;
  73         }
  74
  75         parity = buf[0];
  76         buf++;
  77         switch (parity) {
  78         case 'e':
  79                 cflag |= PARENB;
  80                 break;
  81         case 'o':
  82                 cflag |= PARODD;
  83                 break;
  84         }
  85
  86         bit = simple_strtoul(buf, &buf, 10);
  87         switch (bit) {
  88         case 5:
  89                 cflag |= CS5;
  90                 break;
  91         case 6:
  92                 cflag |= CS6;
  93                 break;
  94         case 7:
  95                 cflag |= CS7;
  96                 break;
  97         default:
  98                 cflag |= CS8;
  99         }
 100
 101 #ifdef CONFIG_SERIAL_BFIN
 102         return bfin_earlyserial_init(serial_port, cflag);
 103 #else
 104         return NULL;
 105 #endif
 106
 107 }
 108 #endif
 109
 110 int __init setup_early_printk(char *buf)
 111 {
 112
 113         /* Crashing in here would be really bad, so check both the var
 114            and the pointer before we start using it
 115          */
 116         if (!buf)
 117                 return 0;
 118
 119         if (!*buf)
 120                 return 0;
 121
 122         if (early_console != NULL)
 123                 return 0;
 124
 125 #ifdef CONFIG_SERIAL_BFIN
 126         /* Check for Blackfin Serial */
 127         if (!strncmp(buf, "serial,uart", 11)) {
 128                 buf += 11;
 129                 early_console = earlyserial_init(buf);
 130         }
 131 #endif
 132
 133 #ifdef CONFIG_BFIN_JTAG_COMM
 134         /* Check for Blackfin JTAG */
 135         if (!strncmp(buf, "jtag", 4)) {
 136                 buf += 4;
 137                 early_console = bfin_jc_early_init();
 138         }
 139 #endif
 140
 141 #ifdef CONFIG_FB
 142                 /* TODO: add framebuffer console support */
 143 #endif
 144
 145         if (likely(early_console)) {
 146                 early_console->flags |= CON_BOOT;
 147
 148                 register_console(early_console);
 149                 printk(KERN_INFO "early printk enabled on %s%d\n",
 150                         early_console->name,
 151                         early_console->index);
 152         }
 153
 154         return 0;
 155 }
 156
 157 /*
 158  * Set up a temporary Event Vector Table, so if something bad happens before
 159  * the kernel is fully started, it doesn't vector off into somewhere we don't
 160  * know
 161  */
 162
 163 asmlinkage void __init init_early_exception_vectors(void)
 164 {
 165         u32 evt;
 166         SSYNC();
 167
 168         /*
 169          * This starts up the shadow buffer, incase anything crashes before
 170          * setup arch
 171          */
 172         mark_shadow_error();
 173         early_shadow_puts(linux_banner);
 174         early_shadow_stamp();
 175
 176         if (CPUID != bfin_cpuid()) {
 177                 early_shadow_puts("Running on wrong machine type, expected");
 178                 early_shadow_reg(CPUID, 16);
 179                 early_shadow_puts(", but running on");
 180                 early_shadow_reg(bfin_cpuid(), 16);
 181                 early_shadow_puts("\n");
 182         }
 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 __attribute__((__noreturn__))
 203 asmlinkage void __init early_trap_c(struct pt_regs *fp, void *retaddr)
 204 {
 205         /* This can happen before the uart is initialized, so initialize
 206          * the UART now (but only if we are running on the processor we think
 207          * we are compiled for - otherwise we write to MMRs that don't exist,
 208          * and cause other problems. Nothing comes out the UART, but it does
 209          * end up in the __buf_log.
 210          */
 211         if (likely(early_console == NULL) && CPUID == bfin_cpuid())
 212                 setup_early_printk(DEFAULT_EARLY_PORT);
 213
 214         if (!shadow_console_enabled()) {
 215                 /* crap - we crashed before setup_arch() */
 216                 early_shadow_puts("panic before setup_arch\n");
 217                 early_shadow_puts("IPEND:");
 218                 early_shadow_reg(fp->ipend, 16);
 219                 if (fp->seqstat & SEQSTAT_EXCAUSE) {
 220                         early_shadow_puts("\nEXCAUSE:");
 221                         early_shadow_reg(fp->seqstat & SEQSTAT_EXCAUSE, 8);
 222                 }
 223                 if (fp->seqstat & SEQSTAT_HWERRCAUSE) {
 224                         early_shadow_puts("\nHWERRCAUSE:");
 225                         early_shadow_reg(
 226                                 (fp->seqstat & SEQSTAT_HWERRCAUSE) >> 14, 8);
 227                 }
 228                 early_shadow_puts("\nErr @");
 229                 if (fp->ipend & EVT_EVX)
 230                         early_shadow_reg(fp->retx, 32);
 231                 else
 232                         early_shadow_reg(fp->pc, 32);
 233 #ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
 234                 early_shadow_puts("\nTrace:");
 235                 if (likely(bfin_read_TBUFSTAT() & TBUFCNT)) {
 236                         while (bfin_read_TBUFSTAT() & TBUFCNT) {
 237                                 early_shadow_puts("\nT  :");
 238                                 early_shadow_reg(bfin_read_TBUF(), 32);
 239                                 early_shadow_puts("\n S :");
 240                                 early_shadow_reg(bfin_read_TBUF(), 32);
 241                         }
 242                 }
 243 #endif
 244                 early_shadow_puts("\nUse bfin-elf-addr2line to determine "
 245                         "function names\n");
 246                 /*
 247                  * We should panic(), but we can't - since panic calls printk,
 248                  * and printk uses memcpy.
 249                  * we want to reboot, but if the machine type is different,
 250                  * can't due to machine specific reboot sequences
 251                  */
 252                 if (CPUID == bfin_cpuid()) {
 253                         early_shadow_puts("Trying to restart\n");
 254                         machine_restart("");
 255                 }
 256
 257                 early_shadow_puts("Halting, since it is not safe to restart\n");
 258                 while (1)
 259                         asm volatile ("EMUEXCPT; IDLE;\n");
 260
 261         } else {
 262                 printk(KERN_EMERG "Early panic\n");
 263                 show_regs(fp);
 264                 dump_bfin_trace_buffer();
 265         }
 266
 267         panic("Died early");
 268 }
 269
 270 early_param("earlyprintk", setup_early_printk);