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/sched/debug.h>
  12 #include <linux/init.h>
  13 #include <linux/serial_core.h>
  14 #include <linux/console.h>
  15 #include <linux/string.h>
  16 #include <linux/reboot.h>
  17 #include <asm/blackfin.h>
  18 #include <asm/irq_handler.h>
  19 #include <asm/early_printk.h>
  20
  21 #ifdef CONFIG_SERIAL_BFIN
  22 extern struct console *bfin_earlyserial_init(unsigned int port,
  23                                                 unsigned int cflag);
  24 #endif
  25 #ifdef CONFIG_BFIN_JTAG_COMM
  26 extern struct console *bfin_jc_early_init(void);
  27 #endif
  28
  29 /* Default console */
  30 #define DEFAULT_PORT 0
  31 #define DEFAULT_CFLAG CS8|B57600
  32
  33 /* Default console for early crashes */
  34 #define DEFAULT_EARLY_PORT "serial,uart0,57600"
  35
  36 #ifdef CONFIG_SERIAL_CORE
  37 /* What should get here is "0,57600" */
  38 static struct console * __init earlyserial_init(char *buf)
  39 {
  40         int baud, bit;
  41         char parity;
  42         unsigned int serial_port = DEFAULT_PORT;
  43         unsigned int cflag = DEFAULT_CFLAG;
  44
  45         serial_port = simple_strtoul(buf, &buf, 10);
  46         buf++;
  47
  48         cflag = 0;
  49         baud = simple_strtoul(buf, &buf, 10);
  50         switch (baud) {
  51         case 1200:
  52                 cflag |= B1200;
  53                 break;
  54         case 2400:
  55                 cflag |= B2400;
  56                 break;
  57         case 4800:
  58                 cflag |= B4800;
  59                 break;
  60         case 9600:
  61                 cflag |= B9600;
  62                 break;
  63         case 19200:
  64                 cflag |= B19200;
  65                 break;
  66         case 38400:
  67                 cflag |= B38400;
  68                 break;
  69         case 115200:
  70                 cflag |= B115200;
  71                 break;
  72         default:
  73                 cflag |= B57600;
  74         }
  75
  76         parity = buf[0];
  77         buf++;
  78         switch (parity) {
  79         case 'e':
  80                 cflag |= PARENB;
  81                 break;
  82         case 'o':
  83                 cflag |= PARODD;
  84                 break;
  85         }
  86
  87         bit = simple_strtoul(buf, &buf, 10);
  88         switch (bit) {
  89         case 5:
  90                 cflag |= CS5;
  91                 break;
  92         case 6:
  93                 cflag |= CS6;
  94                 break;
  95         case 7:
  96                 cflag |= CS7;
  97                 break;
  98         default:
  99                 cflag |= CS8;
 100         }
 101
 102 #ifdef CONFIG_SERIAL_BFIN
 103         return bfin_earlyserial_init(serial_port, cflag);
 104 #else
 105         return NULL;
 106 #endif
 107
 108 }
 109 #endif
 110
 111 int __init setup_early_printk(char *buf)
 112 {
 113
 114         /* Crashing in here would be really bad, so check both the var
 115            and the pointer before we start using it
 116          */
 117         if (!buf)
 118                 return 0;
 119
 120         if (!*buf)
 121                 return 0;
 122
 123         if (early_console != NULL)
 124                 return 0;
 125
 126 #ifdef CONFIG_SERIAL_BFIN
 127         /* Check for Blackfin Serial */
 128         if (!strncmp(buf, "serial,uart", 11)) {
 129                 buf += 11;
 130                 early_console = earlyserial_init(buf);
 131         }
 132 #endif
 133
 134 #ifdef CONFIG_BFIN_JTAG_COMM
 135         /* Check for Blackfin JTAG */
 136         if (!strncmp(buf, "jtag", 4)) {
 137                 buf += 4;
 138                 early_console = bfin_jc_early_init();
 139         }
 140 #endif
 141
 142 #ifdef CONFIG_FB
 143                 /* TODO: add framebuffer console support */
 144 #endif
 145
 146         if (likely(early_console)) {
 147                 early_console->flags |= CON_BOOT;
 148
 149                 register_console(early_console);
 150                 printk(KERN_INFO "early printk enabled on %s%d\n",
 151                         early_console->name,
 152                         early_console->index);
 153         }
 154
 155         return 0;
 156 }
 157
 158 /*
 159  * Set up a temporary Event Vector Table, so if something bad happens before
 160  * the kernel is fully started, it doesn't vector off into somewhere we don't
 161  * know
 162  */
 163
 164 asmlinkage void __init init_early_exception_vectors(void)
 165 {
 166         u32 evt;
 167         SSYNC();
 168
 169         /*
 170          * This starts up the shadow buffer, incase anything crashes before
 171          * setup arch
 172          */
 173         mark_shadow_error();
 174         early_shadow_puts(linux_banner);
 175         early_shadow_stamp();
 176
 177         if (CPUID != bfin_cpuid()) {
 178                 early_shadow_puts("Running on wrong machine type, expected");
 179                 early_shadow_reg(CPUID, 16);
 180                 early_shadow_puts(", but running on");
 181                 early_shadow_reg(bfin_cpuid(), 16);
 182                 early_shadow_puts("\n");
 183         }
 184
 185         /* cannot program in software:
 186          * evt0 - emulation (jtag)
 187          * evt1 - reset
 188          */
 189         for (evt = EVT2; evt <= EVT15; evt += 4)
 190                 bfin_write32(evt, early_trap);
 191         CSYNC();
 192
 193         /* Set all the return from interrupt, exception, NMI to a known place
 194          * so if we do a RETI, RETX or RETN by mistake - we go somewhere known
 195          * Note - don't change RETS - we are in a subroutine, or
 196          * RETE - since it might screw up if emulator is attached
 197          */
 198         asm("\tRETI = %0; RETX = %0; RETN = %0;\n"
 199                 : : "p"(early_trap));
 200
 201 }
 202
 203 __attribute__((__noreturn__))
 204 asmlinkage void __init early_trap_c(struct pt_regs *fp, void *retaddr)
 205 {
 206         /* This can happen before the uart is initialized, so initialize
 207          * the UART now (but only if we are running on the processor we think
 208          * we are compiled for - otherwise we write to MMRs that don't exist,
 209          * and cause other problems. Nothing comes out the UART, but it does
 210          * end up in the __buf_log.
 211          */
 212         if (likely(early_console == NULL) && CPUID == bfin_cpuid())
 213                 setup_early_printk(DEFAULT_EARLY_PORT);
 214
 215         if (!shadow_console_enabled()) {
 216                 /* crap - we crashed before setup_arch() */
 217                 early_shadow_puts("panic before setup_arch\n");
 218                 early_shadow_puts("IPEND:");
 219                 early_shadow_reg(fp->ipend, 16);
 220                 if (fp->seqstat & SEQSTAT_EXCAUSE) {
 221                         early_shadow_puts("\nEXCAUSE:");
 222                         early_shadow_reg(fp->seqstat & SEQSTAT_EXCAUSE, 8);
 223                 }
 224                 if (fp->seqstat & SEQSTAT_HWERRCAUSE) {
 225                         early_shadow_puts("\nHWERRCAUSE:");
 226                         early_shadow_reg(
 227                                 (fp->seqstat & SEQSTAT_HWERRCAUSE) >> 14, 8);
 228                 }
 229                 early_shadow_puts("\nErr @");
 230                 if (fp->ipend & EVT_EVX)
 231                         early_shadow_reg(fp->retx, 32);
 232                 else
 233                         early_shadow_reg(fp->pc, 32);
 234 #ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
 235                 early_shadow_puts("\nTrace:");
 236                 if (likely(bfin_read_TBUFSTAT() & TBUFCNT)) {
 237                         while (bfin_read_TBUFSTAT() & TBUFCNT) {
 238                                 early_shadow_puts("\nT  :");
 239                                 early_shadow_reg(bfin_read_TBUF(), 32);
 240                                 early_shadow_puts("\n S :");
 241                                 early_shadow_reg(bfin_read_TBUF(), 32);
 242                         }
 243                 }
 244 #endif
 245                 early_shadow_puts("\nUse bfin-elf-addr2line to determine "
 246                         "function names\n");
 247                 /*
 248                  * We should panic(), but we can't - since panic calls printk,
 249                  * and printk uses memcpy.
 250                  * we want to reboot, but if the machine type is different,
 251                  * can't due to machine specific reboot sequences
 252                  */
 253                 if (CPUID == bfin_cpuid()) {
 254                         early_shadow_puts("Trying to restart\n");
 255                         machine_restart("");
 256                 }
 257
 258                 early_shadow_puts("Halting, since it is not safe to restart\n");
 259                 while (1)
 260                         asm volatile ("EMUEXCPT; IDLE;\n");
 261
 262         } else {
 263                 printk(KERN_EMERG "Early panic\n");
 264                 show_regs(fp);
 265                 dump_bfin_trace_buffer();
 266         }
 267
 268         panic("Died early");
 269 }
 270
 271 early_param("earlyprintk", setup_early_printk);