arch/x86_64/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
  10 /* Simple VGA output */
  11
  12 #ifdef __i386__
  13 #include <asm/setup.h>
  14 #define VGABASE         (__ISA_IO_base + 0xb8000)
  15 #else
  16 #include <asm/bootsetup.h>
  17 #define VGABASE         ((void __iomem *)0xffffffff800b8000UL)
  18 #endif
  19
  20 static int max_ypos = 25, max_xpos = 80;
  21 static int current_ypos = 25, current_xpos = 0;
  22
  23 #ifndef CONFIG_XEN
  24 static void early_vga_write(struct console *con, const char *str, unsigned n)
  25 {
  26         char c;
  27         int  i, k, j;
  28
  29         while ((c = *str++) != '\0' && n-- > 0) {
  30                 if (current_ypos >= max_ypos) {
  31                         /* scroll 1 line up */
  32                         for (k = 1, j = 0; k < max_ypos; k++, j++) {
  33                                 for (i = 0; i < max_xpos; i++) {
  34                                         writew(readw(VGABASE+2*(max_xpos*k+i)),
  35                                                VGABASE + 2*(max_xpos*j + i));
  36                                 }
  37                         }
  38                         for (i = 0; i < max_xpos; i++)
  39                                 writew(0x720, VGABASE + 2*(max_xpos*j + i));
  40                         current_ypos = max_ypos-1;
  41                 }
  42                 if (c == '\n') {
  43                         current_xpos = 0;
  44                         current_ypos++;
  45                 } else if (c != '\r')  {
  46                         writew(((0x7 << 8) | (unsigned short) c),
  47                                VGABASE + 2*(max_xpos*current_ypos +
  48                                                 current_xpos++));
  49                         if (current_xpos >= max_xpos) {
  50                                 current_xpos = 0;
  51                                 current_ypos++;
  52                         }
  53                 }
  54         }
  55 }
  56
  57 static struct console early_vga_console = {
  58         .name =         "earlyvga",
  59         .write =        early_vga_write,
  60         .flags =        CON_PRINTBUFFER,
  61         .index =        -1,
  62 };
  63
  64 /* Serial functions loosely based on a similar package from Klaus P. Gerlicher */
  65
  66 static int early_serial_base = 0x3f8;  /* ttyS0 */
  67
  68 #define XMTRDY          0x20
  69
  70 #define DLAB            0x80
  71
  72 #define TXR             0       /*  Transmit register (WRITE) */
  73 #define RXR             0       /*  Receive register  (READ)  */
  74 #define IER             1       /*  Interrupt Enable          */
  75 #define IIR             2       /*  Interrupt ID              */
  76 #define FCR             2       /*  FIFO control              */
  77 #define LCR             3       /*  Line control              */
  78 #define MCR             4       /*  Modem control             */
  79 #define LSR             5       /*  Line Status               */
  80 #define MSR             6       /*  Modem Status              */
  81 #define DLL             0       /*  Divisor Latch Low         */
  82 #define DLH             1       /*  Divisor latch High        */
  83
  84 static int early_serial_putc(unsigned char ch)
  85 {
  86         unsigned timeout = 0xffff;
  87         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
  88                 cpu_relax();
  89         outb(ch, early_serial_base + TXR);
  90         return timeout ? 0 : -1;
  91 }
  92
  93 static void early_serial_write(struct console *con, const char *s, unsigned n)
  94 {
  95         while (*s && n-- > 0) {
  96                 early_serial_putc(*s);
  97                 if (*s == '\n')
  98                         early_serial_putc('\r');
  99                 s++;
 100         }
 101 }
 102
 103 #define DEFAULT_BAUD 9600
 104
 105 static __init void early_serial_init(char *s)
 106 {
 107         unsigned char c;
 108         unsigned divisor;
 109         unsigned baud = DEFAULT_BAUD;
 110         char *e;
 111
 112         if (*s == ',')
 113                 ++s;
 114
 115         if (*s) {
 116                 unsigned port;
 117                 if (!strncmp(s,"0x",2)) {
 118                         early_serial_base = simple_strtoul(s, &e, 16);
 119                 } else {
 120                         static int bases[] = { 0x3f8, 0x2f8 };
 121
 122                         if (!strncmp(s,"ttyS",4))
 123                                 s += 4;
 124                         port = simple_strtoul(s, &e, 10);
 125                         if (port > 1 || s == e)
 126                                 port = 0;
 127                         early_serial_base = bases[port];
 128                 }
 129                 s += strcspn(s, ",");
 130                 if (*s == ',')
 131                         s++;
 132         }
 133
 134         outb(0x3, early_serial_base + LCR);     /* 8n1 */
 135         outb(0, early_serial_base + IER);       /* no interrupt */
 136         outb(0, early_serial_base + FCR);       /* no fifo */
 137         outb(0x3, early_serial_base + MCR);     /* DTR + RTS */
 138
 139         if (*s) {
 140                 baud = simple_strtoul(s, &e, 0);
 141                 if (baud == 0 || s == e)
 142                         baud = DEFAULT_BAUD;
 143         }
 144
 145         divisor = 115200 / baud;
 146         c = inb(early_serial_base + LCR);
 147         outb(c | DLAB, early_serial_base + LCR);
 148         outb(divisor & 0xff, early_serial_base + DLL);
 149         outb((divisor >> 8) & 0xff, early_serial_base + DLH);
 150         outb(c & ~DLAB, early_serial_base + LCR);
 151 }
 152
 153 #else /* CONFIG_XEN */
 154
 155 #undef SCREEN_INFO
 156 #define SCREEN_INFO screen_info
 157 extern struct screen_info screen_info;
 158
 159 static void
 160 early_serial_write(struct console *con, const char *s, unsigned count)
 161 {
 162         int n;
 163
 164         while (count > 0) {
 165                 n = HYPERVISOR_console_io(CONSOLEIO_write, count, (char *)s);
 166                 if (n <= 0)
 167                         break;
 168                 count -= n;
 169                 s += n;
 170         }
 171 }
 172
 173 static __init void early_serial_init(char *s)
 174 {
 175         current_xpos = 0;
 176 }
 177
 178 /*
 179  * No early VGA console on Xen, as we do not have convenient ISA-space
 180  * mappings. Someone should fix this for domain 0. For now, use fake serial.
 181  */
 182 #define early_vga_console early_serial_console
 183
 184 #endif
 185
 186 static struct console early_serial_console = {
 187         .name =         "earlyser",
 188         .write =        early_serial_write,
 189         .flags =        CON_PRINTBUFFER,
 190         .index =        -1,
 191 };
 192
 193 /* Console interface to a host file on AMD's SimNow! */
 194
 195 static int simnow_fd;
 196
 197 enum {
 198         MAGIC1 = 0xBACCD00A,
 199         MAGIC2 = 0xCA110000,
 200         XOPEN = 5,
 201         XWRITE = 4,
 202 };
 203
 204 static noinline long simnow(long cmd, long a, long b, long c)
 205 {
 206         long ret;
 207         asm volatile("cpuid" :
 208                      "=a" (ret) :
 209                      "b" (a), "c" (b), "d" (c), "0" (MAGIC1), "D" (cmd + MAGIC2));
 210         return ret;
 211 }
 212
 213 void __init simnow_init(char *str)
 214 {
 215         char *fn = "klog";
 216         if (*str == '=')
 217                 fn = ++str;
 218         /* error ignored */
 219         simnow_fd = simnow(XOPEN, (unsigned long)fn, O_WRONLY|O_APPEND|O_CREAT, 0644);
 220 }
 221
 222 static void simnow_write(struct console *con, const char *s, unsigned n)
 223 {
 224         simnow(XWRITE, simnow_fd, (unsigned long)s, n);
 225 }
 226
 227 static struct console simnow_console = {
 228         .name =         "simnow",
 229         .write =        simnow_write,
 230         .flags =        CON_PRINTBUFFER,
 231         .index =        -1,
 232 };
 233
 234 /* Direct interface for emergencies */
 235 struct console *early_console = &early_vga_console;
 236 static int early_console_initialized = 0;
 237
 238 void early_printk(const char *fmt, ...)
 239 {
 240         char buf[512];
 241         int n;
 242         va_list ap;
 243
 244         va_start(ap,fmt);
 245         n = vscnprintf(buf,512,fmt,ap);
 246         early_console->write(early_console,buf,n);
 247         va_end(ap);
 248 }
 249
 250 static int __initdata keep_early;
 251
 252 static int __init setup_early_printk(char *buf)
 253 {
 254         if (!buf)
 255                 return 0;
 256
 257         if (early_console_initialized)
 258                 return 0;
 259         early_console_initialized = 1;
 260
 261         if (strstr(buf, "keep"))
 262                 keep_early = 1;
 263
 264         if (!strncmp(buf, "serial", 6)) {
 265                 early_serial_init(buf + 6);
 266                 early_console = &early_serial_console;
 267         } else if (!strncmp(buf, "ttyS", 4)) {
 268                 early_serial_init(buf);
 269                 early_console = &early_serial_console;
 270         } else if (!strncmp(buf, "vga", 3)
 271                    && SCREEN_INFO.orig_video_isVGA == 1) {
 272                 max_xpos = SCREEN_INFO.orig_video_cols;
 273                 max_ypos = SCREEN_INFO.orig_video_lines;
 274                 current_ypos = SCREEN_INFO.orig_y;
 275                 early_console = &early_vga_console;
 276         } else if (!strncmp(buf, "simnow", 6)) {
 277                 simnow_init(buf + 6);
 278                 early_console = &simnow_console;
 279                 keep_early = 1;
 280         }
 281         register_console(early_console);
 282         return 0;
 283 }
 284
 285 early_param("earlyprintk", setup_early_printk);
 286
 287 void __init disable_early_printk(void)
 288 {
 289         if (!early_console_initialized || !early_console)
 290                 return;
 291         if (!keep_early) {
 292                 printk("disabling early console\n");
 293                 unregister_console(early_console);
 294                 early_console_initialized = 0;
 295         } else {
 296                 printk("keeping early console\n");
 297         }
 298 }
 299