arch/x86/kernel/early_printk.c

   1 #include <linux/console.h>
   2 #include <linux/kernel.h>
   3 #include <linux/init.h>
   4 #include <linux/string.h>
   5 #include <linux/screen_info.h>
   6 #include <asm/io.h>
   7 #include <asm/processor.h>
   8 #include <asm/fcntl.h>
   9 #include <asm/setup.h>
  10 #include <xen/hvc-console.h>
  11
  12 /* Simple VGA output */
  13 #define VGABASE         (__ISA_IO_base + 0xb8000)
  14
  15 static int max_ypos = 25, max_xpos = 80;
  16 static int current_ypos = 25, current_xpos;
  17
  18 static void early_vga_write(struct console *con, const char *str, unsigned n)
  19 {
  20         char c;
  21         int  i, k, j;
  22
  23         while ((c = *str++) != '\0' && n-- > 0) {
  24                 if (current_ypos >= max_ypos) {
  25                         /* scroll 1 line up */
  26                         for (k = 1, j = 0; k < max_ypos; k++, j++) {
  27                                 for (i = 0; i < max_xpos; i++) {
  28                                         writew(readw(VGABASE+2*(max_xpos*k+i)),
  29                                                VGABASE + 2*(max_xpos*j + i));
  30                                 }
  31                         }
  32                         for (i = 0; i < max_xpos; i++)
  33                                 writew(0x720, VGABASE + 2*(max_xpos*j + i));
  34                         current_ypos = max_ypos-1;
  35                 }
  36                 if (c == '\n') {
  37                         current_xpos = 0;
  38                         current_ypos++;
  39                 } else if (c != '\r')  {
  40                         writew(((0x7 << 8) | (unsigned short) c),
  41                                VGABASE + 2*(max_xpos*current_ypos +
  42                                                 current_xpos++));
  43                         if (current_xpos >= max_xpos) {
  44                                 current_xpos = 0;
  45                                 current_ypos++;
  46                         }
  47                 }
  48         }
  49 }
  50
  51 static struct console early_vga_console = {
  52         .name =         "earlyvga",
  53         .write =        early_vga_write,
  54         .flags =        CON_PRINTBUFFER,
  55         .index =        -1,
  56 };
  57
  58 /* Serial functions loosely based on a similar package from Klaus P. Gerlicher */
  59
  60 static int early_serial_base = 0x3f8;  /* ttyS0 */
  61
  62 #define XMTRDY          0x20
  63
  64 #define DLAB            0x80
  65
  66 #define TXR             0       /*  Transmit register (WRITE) */
  67 #define RXR             0       /*  Receive register  (READ)  */
  68 #define IER             1       /*  Interrupt Enable          */
  69 #define IIR             2       /*  Interrupt ID              */
  70 #define FCR             2       /*  FIFO control              */
  71 #define LCR             3       /*  Line control              */
  72 #define MCR             4       /*  Modem control             */
  73 #define LSR             5       /*  Line Status               */
  74 #define MSR             6       /*  Modem Status              */
  75 #define DLL             0       /*  Divisor Latch Low         */
  76 #define DLH             1       /*  Divisor latch High        */
  77
  78 static int early_serial_putc(unsigned char ch)
  79 {
  80         unsigned timeout = 0xffff;
  81         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
  82                 cpu_relax();
  83         outb(ch, early_serial_base + TXR);
  84         return timeout ? 0 : -1;
  85 }
  86
  87 static void early_serial_write(struct console *con, const char *s, unsigned n)
  88 {
  89         while (*s && n-- > 0) {
  90                 if (*s == '\n')
  91                         early_serial_putc('\r');
  92                 early_serial_putc(*s);
  93                 s++;
  94         }
  95 }
  96
  97 #define DEFAULT_BAUD 9600
  98
  99 static __init void early_serial_init(char *s)
 100 {
 101         unsigned char c;
 102         unsigned divisor;
 103         unsigned baud = DEFAULT_BAUD;
 104         char *e;
 105
 106         if (*s == ',')
 107                 ++s;
 108
 109         if (*s) {
 110                 unsigned port;
 111                 if (!strncmp(s, "0x", 2)) {
 112                         early_serial_base = simple_strtoul(s, &e, 16);
 113                 } else {
 114                         static int bases[] = { 0x3f8, 0x2f8 };
 115
 116                         if (!strncmp(s, "ttyS", 4))
 117                                 s += 4;
 118                         port = simple_strtoul(s, &e, 10);
 119                         if (port > 1 || s == e)
 120                                 port = 0;
 121                         early_serial_base = bases[port];
 122                 }
 123                 s += strcspn(s, ",");
 124                 if (*s == ',')
 125                         s++;
 126         }
 127
 128         outb(0x3, early_serial_base + LCR);     /* 8n1 */
 129         outb(0, early_serial_base + IER);       /* no interrupt */
 130         outb(0, early_serial_base + FCR);       /* no fifo */
 131         outb(0x3, early_serial_base + MCR);     /* DTR + RTS */
 132
 133         if (*s) {
 134                 baud = simple_strtoul(s, &e, 0);
 135                 if (baud == 0 || s == e)
 136                         baud = DEFAULT_BAUD;
 137         }
 138
 139         divisor = 115200 / baud;
 140         c = inb(early_serial_base + LCR);
 141         outb(c | DLAB, early_serial_base + LCR);
 142         outb(divisor & 0xff, early_serial_base + DLL);
 143         outb((divisor >> 8) & 0xff, early_serial_base + DLH);
 144         outb(c & ~DLAB, early_serial_base + LCR);
 145 }
 146
 147 static struct console early_serial_console = {
 148         .name =         "earlyser",
 149         .write =        early_serial_write,
 150         .flags =        CON_PRINTBUFFER,
 151         .index =        -1,
 152 };
 153
 154 /* Console interface to a host file on AMD's SimNow! */
 155
 156 static int simnow_fd;
 157
 158 enum {
 159         MAGIC1 = 0xBACCD00A,
 160         MAGIC2 = 0xCA110000,
 161         XOPEN = 5,
 162         XWRITE = 4,
 163 };
 164
 165 static noinline long simnow(long cmd, long a, long b, long c)
 166 {
 167         long ret;
 168         asm volatile("cpuid" :
 169                      "=a" (ret) :
 170                      "b" (a), "c" (b), "d" (c), "0" (MAGIC1), "D" (cmd + MAGIC2));
 171         return ret;
 172 }
 173
 174 static void __init simnow_init(char *str)
 175 {
 176         char *fn = "klog";
 177         if (*str == '=')
 178                 fn = ++str;
 179         /* error ignored */
 180         simnow_fd = simnow(XOPEN, (unsigned long)fn, O_WRONLY|O_APPEND|O_CREAT, 0644);
 181 }
 182
 183 static void simnow_write(struct console *con, const char *s, unsigned n)
 184 {
 185         simnow(XWRITE, simnow_fd, (unsigned long)s, n);
 186 }
 187
 188 static struct console simnow_console = {
 189         .name =         "simnow",
 190         .write =        simnow_write,
 191         .flags =        CON_PRINTBUFFER,
 192         .index =        -1,
 193 };
 194
 195 /* Direct interface for emergencies */
 196 static struct console *early_console = &early_vga_console;
 197 static int early_console_initialized;
 198
 199 void early_printk(const char *fmt, ...)
 200 {
 201         char buf[512];
 202         int n;
 203         va_list ap;
 204
 205         va_start(ap, fmt);
 206         n = vscnprintf(buf, 512, fmt, ap);
 207         early_console->write(early_console, buf, n);
 208         va_end(ap);
 209 }
 210
 211 static int __initdata keep_early;
 212
 213 static int __init setup_early_printk(char *buf)
 214 {
 215         if (!buf)
 216                 return 0;
 217
 218         if (early_console_initialized)
 219                 return 0;
 220         early_console_initialized = 1;
 221
 222         if (strstr(buf, "keep"))
 223                 keep_early = 1;
 224
 225         if (!strncmp(buf, "serial", 6)) {
 226                 early_serial_init(buf + 6);
 227                 early_console = &early_serial_console;
 228         } else if (!strncmp(buf, "ttyS", 4)) {
 229                 early_serial_init(buf);
 230                 early_console = &early_serial_console;
 231         } else if (!strncmp(buf, "vga", 3)
 232                 && boot_params.screen_info.orig_video_isVGA == 1) {
 233                 max_xpos = boot_params.screen_info.orig_video_cols;
 234                 max_ypos = boot_params.screen_info.orig_video_lines;
 235                 current_ypos = boot_params.screen_info.orig_y;
 236                 early_console = &early_vga_console;
 237         } else if (!strncmp(buf, "simnow", 6)) {
 238                 simnow_init(buf + 6);
 239                 early_console = &simnow_console;
 240                 keep_early = 1;
 241 #ifdef CONFIG_HVC_XEN
 242         } else if (!strncmp(buf, "xen", 3)) {
 243                 early_console = &xenboot_console;
 244 #endif
 245         }
 246
 247         if (keep_early)
 248                 early_console->flags &= ~CON_BOOT;
 249         else
 250                 early_console->flags |= CON_BOOT;
 251         register_console(early_console);
 252         return 0;
 253 }
 254 early_param("earlyprintk", setup_early_printk);