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/tty.h>
   6 #include <asm/io.h>
   7 #include <asm/processor.h>
   8
   9 /* Simple VGA output */
  10
  11 #ifdef __i386__
  12 #include <asm/setup.h>
  13 #define VGABASE         (__ISA_IO_base + 0xb8000)
  14 #else
  15 #include <asm/bootsetup.h>
  16 #define VGABASE         ((void __iomem *)0xffffffff800b8000UL)
  17 #endif
  18
  19 #define MAX_YPOS        max_ypos
  20 #define MAX_XPOS        max_xpos
  21
  22 static int max_ypos = 25, max_xpos = 80;
  23 static int current_ypos = 1, current_xpos = 0;
  24
  25 static void early_vga_write(struct console *con, const char *str, unsigned n)
  26 {
  27         char c;
  28         int  i, k, j;
  29
  30         while ((c = *str++) != '\0' && n-- > 0) {
  31                 if (current_ypos >= MAX_YPOS) {
  32                         /* scroll 1 line up */
  33                         for (k = 1, j = 0; k < MAX_YPOS; k++, j++) {
  34                                 for (i = 0; i < MAX_XPOS; i++) {
  35                                         writew(readw(VGABASE + 2*(MAX_XPOS*k + i)),
  36                                                VGABASE + 2*(MAX_XPOS*j + i));
  37                                 }
  38                         }
  39                         for (i = 0; i < MAX_XPOS; i++)
  40                                 writew(0x720, VGABASE + 2*(MAX_XPOS*j + i));
  41                         current_ypos = MAX_YPOS-1;
  42                 }
  43                 if (c == '\n') {
  44                         current_xpos = 0;
  45                         current_ypos++;
  46                 } else if (c != '\r')  {
  47                         writew(((0x7 << 8) | (unsigned short) c),
  48                                VGABASE + 2*(MAX_XPOS*current_ypos +
  49                                                 current_xpos++));
  50                         if (current_xpos >= MAX_XPOS) {
  51                                 current_xpos = 0;
  52                                 current_ypos++;
  53                         }
  54                 }
  55         }
  56 }
  57
  58 static struct console early_vga_console = {
  59         .name =         "earlyvga",
  60         .write =        early_vga_write,
  61         .flags =        CON_PRINTBUFFER,
  62         .index =        -1,
  63 };
  64
  65 /* Serial functions loosely based on a similar package from Klaus P. Gerlicher */
  66
  67 static int early_serial_base = 0x3f8;  /* ttyS0 */
  68
  69 #define XMTRDY          0x20
  70
  71 #define DLAB            0x80
  72
  73 #define TXR             0       /*  Transmit register (WRITE) */
  74 #define RXR             0       /*  Receive register  (READ)  */
  75 #define IER             1       /*  Interrupt Enable          */
  76 #define IIR             2       /*  Interrupt ID              */
  77 #define FCR             2       /*  FIFO control              */
  78 #define LCR             3       /*  Line control              */
  79 #define MCR             4       /*  Modem control             */
  80 #define LSR             5       /*  Line Status               */
  81 #define MSR             6       /*  Modem Status              */
  82 #define DLL             0       /*  Divisor Latch Low         */
  83 #define DLH             1       /*  Divisor latch High        */
  84
  85 static int early_serial_putc(unsigned char ch)
  86 {
  87         unsigned timeout = 0xffff;
  88         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
  89                 cpu_relax();
  90         outb(ch, early_serial_base + TXR);
  91         return timeout ? 0 : -1;
  92 }
  93
  94 static void early_serial_write(struct console *con, const char *s, unsigned n)
  95 {
  96         while (*s && n-- > 0) {
  97                 early_serial_putc(*s);
  98                 if (*s == '\n')
  99                         early_serial_putc('\r');
 100                 s++;
 101         }
 102 }
 103
 104 #define DEFAULT_BAUD 9600
 105
 106 static __init void early_serial_init(char *s)
 107 {
 108         unsigned char c;
 109         unsigned divisor;
 110         unsigned baud = DEFAULT_BAUD;
 111         char *e;
 112
 113         if (*s == ',')
 114                 ++s;
 115
 116         if (*s) {
 117                 unsigned port;
 118                 if (!strncmp(s,"0x",2)) {
 119                         early_serial_base = simple_strtoul(s, &e, 16);
 120                 } else {
 121                         static int bases[] = { 0x3f8, 0x2f8 };
 122
 123                         if (!strncmp(s,"ttyS",4))
 124                                 s += 4;
 125                         port = simple_strtoul(s, &e, 10);
 126                         if (port > 1 || s == e)
 127                                 port = 0;
 128                         early_serial_base = bases[port];
 129                 }
 130                 s += strcspn(s, ",");
 131                 if (*s == ',')
 132                         s++;
 133         }
 134
 135         outb(0x3, early_serial_base + LCR);     /* 8n1 */
 136         outb(0, early_serial_base + IER);       /* no interrupt */
 137         outb(0, early_serial_base + FCR);       /* no fifo */
 138         outb(0x3, early_serial_base + MCR);     /* DTR + RTS */
 139
 140         if (*s) {
 141                 baud = simple_strtoul(s, &e, 0);
 142                 if (baud == 0 || s == e)
 143                         baud = DEFAULT_BAUD;
 144         }
 145
 146         divisor = 115200 / baud;
 147         c = inb(early_serial_base + LCR);
 148         outb(c | DLAB, early_serial_base + LCR);
 149         outb(divisor & 0xff, early_serial_base + DLL);
 150         outb((divisor >> 8) & 0xff, early_serial_base + DLH);
 151         outb(c & ~DLAB, early_serial_base + LCR);
 152 }
 153
 154 static struct console early_serial_console = {
 155         .name =         "earlyser",
 156         .write =        early_serial_write,
 157         .flags =        CON_PRINTBUFFER,
 158         .index =        -1,
 159 };
 160
 161 /* Direct interface for emergencies */
 162 struct console *early_console = &early_vga_console;
 163 static int early_console_initialized = 0;
 164
 165 void early_printk(const char *fmt, ...)
 166 {
 167         char buf[512];
 168         int n;
 169         va_list ap;
 170
 171         va_start(ap,fmt);
 172         n = vscnprintf(buf,512,fmt,ap);
 173         early_console->write(early_console,buf,n);
 174         va_end(ap);
 175 }
 176
 177 static int keep_early;
 178
 179 int __init setup_early_printk(char *opt)
 180 {
 181         char *space;
 182         char buf[256];
 183
 184         if (early_console_initialized)
 185                 return -1;
 186
 187         opt = strchr(opt, '=') + 1;
 188
 189         strlcpy(buf,opt,sizeof(buf));
 190         space = strchr(buf, ' ');
 191         if (space)
 192                 *space = 0;
 193
 194         if (strstr(buf,"keep"))
 195                 keep_early = 1;
 196
 197         if (!strncmp(buf, "serial", 6)) {
 198                 early_serial_init(buf + 6);
 199                 early_console = &early_serial_console;
 200         } else if (!strncmp(buf, "ttyS", 4)) {
 201                 early_serial_init(buf);
 202                 early_console = &early_serial_console;
 203         } else if (!strncmp(buf, "vga", 3)
 204                    && SCREEN_INFO.orig_video_isVGA == 1) {
 205                 max_xpos = SCREEN_INFO.orig_video_cols;
 206                 max_ypos = SCREEN_INFO.orig_video_lines;
 207                 early_console = &early_vga_console;
 208         }
 209         early_console_initialized = 1;
 210         register_console(early_console);
 211         return 0;
 212 }
 213
 214 void __init disable_early_printk(void)
 215 {
 216         if (!early_console_initialized || !early_console)
 217                 return;
 218         if (!keep_early) {
 219                 printk("disabling early console\n");
 220                 unregister_console(early_console);
 221                 early_console_initialized = 0;
 222         } else {
 223                 printk("keeping early console\n");
 224         }
 225 }
 226
 227 __setup("earlyprintk=", setup_early_printk);