linux/arch/x86/kernel/early_printk.c
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   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 <linux/usb/ch9.h>
   7#include <linux/pci_regs.h>
   8#include <linux/pci_ids.h>
   9#include <linux/errno.h>
  10#include <asm/io.h>
  11#include <asm/processor.h>
  12#include <asm/fcntl.h>
  13#include <asm/setup.h>
  14#include <xen/hvc-console.h>
  15#include <asm/pci-direct.h>
  16#include <asm/fixmap.h>
  17#include <asm/intel-mid.h>
  18#include <asm/pgtable.h>
  19#include <linux/usb/ehci_def.h>
  20#include <linux/efi.h>
  21#include <asm/efi.h>
  22
  23/* Simple VGA output */
  24#define VGABASE         (__ISA_IO_base + 0xb8000)
  25
  26static int max_ypos = 25, max_xpos = 80;
  27static int current_ypos = 25, current_xpos;
  28
  29static void early_vga_write(struct console *con, const char *str, unsigned n)
  30{
  31        char c;
  32        int  i, k, j;
  33
  34        while ((c = *str++) != '\0' && n-- > 0) {
  35                if (current_ypos >= max_ypos) {
  36                        /* scroll 1 line up */
  37                        for (k = 1, j = 0; k < max_ypos; k++, j++) {
  38                                for (i = 0; i < max_xpos; i++) {
  39                                        writew(readw(VGABASE+2*(max_xpos*k+i)),
  40                                               VGABASE + 2*(max_xpos*j + i));
  41                                }
  42                        }
  43                        for (i = 0; i < max_xpos; i++)
  44                                writew(0x720, VGABASE + 2*(max_xpos*j + i));
  45                        current_ypos = max_ypos-1;
  46                }
  47#ifdef CONFIG_KGDB_KDB
  48                if (c == '\b') {
  49                        if (current_xpos > 0)
  50                                current_xpos--;
  51                } else if (c == '\r') {
  52                        current_xpos = 0;
  53                } else
  54#endif
  55                if (c == '\n') {
  56                        current_xpos = 0;
  57                        current_ypos++;
  58                } else if (c != '\r')  {
  59                        writew(((0x7 << 8) | (unsigned short) c),
  60                               VGABASE + 2*(max_xpos*current_ypos +
  61                                                current_xpos++));
  62                        if (current_xpos >= max_xpos) {
  63                                current_xpos = 0;
  64                                current_ypos++;
  65                        }
  66                }
  67        }
  68}
  69
  70static struct console early_vga_console = {
  71        .name =         "earlyvga",
  72        .write =        early_vga_write,
  73        .flags =        CON_PRINTBUFFER,
  74        .index =        -1,
  75};
  76
  77/* Serial functions loosely based on a similar package from Klaus P. Gerlicher */
  78
  79static int early_serial_base = 0x3f8;  /* ttyS0 */
  80
  81#define XMTRDY          0x20
  82
  83#define DLAB            0x80
  84
  85#define TXR             0       /*  Transmit register (WRITE) */
  86#define RXR             0       /*  Receive register  (READ)  */
  87#define IER             1       /*  Interrupt Enable          */
  88#define IIR             2       /*  Interrupt ID              */
  89#define FCR             2       /*  FIFO control              */
  90#define LCR             3       /*  Line control              */
  91#define MCR             4       /*  Modem control             */
  92#define LSR             5       /*  Line Status               */
  93#define MSR             6       /*  Modem Status              */
  94#define DLL             0       /*  Divisor Latch Low         */
  95#define DLH             1       /*  Divisor latch High        */
  96
  97static int early_serial_putc(unsigned char ch)
  98{
  99        unsigned timeout = 0xffff;
 100
 101        while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
 102                cpu_relax();
 103        outb(ch, early_serial_base + TXR);
 104        return timeout ? 0 : -1;
 105}
 106
 107static void early_serial_write(struct console *con, const char *s, unsigned n)
 108{
 109        while (*s && n-- > 0) {
 110                if (*s == '\n')
 111                        early_serial_putc('\r');
 112                early_serial_putc(*s);
 113                s++;
 114        }
 115}
 116
 117#define DEFAULT_BAUD 9600
 118
 119static __init void early_serial_init(char *s)
 120{
 121        unsigned char c;
 122        unsigned divisor;
 123        unsigned baud = DEFAULT_BAUD;
 124        char *e;
 125
 126        if (*s == ',')
 127                ++s;
 128
 129        if (*s) {
 130                unsigned port;
 131                if (!strncmp(s, "0x", 2)) {
 132                        early_serial_base = simple_strtoul(s, &e, 16);
 133                } else {
 134                        static const int __initconst bases[] = { 0x3f8, 0x2f8 };
 135
 136                        if (!strncmp(s, "ttyS", 4))
 137                                s += 4;
 138                        port = simple_strtoul(s, &e, 10);
 139                        if (port > 1 || s == e)
 140                                port = 0;
 141                        early_serial_base = bases[port];
 142                }
 143                s += strcspn(s, ",");
 144                if (*s == ',')
 145                        s++;
 146        }
 147
 148        outb(0x3, early_serial_base + LCR);     /* 8n1 */
 149        outb(0, early_serial_base + IER);       /* no interrupt */
 150        outb(0, early_serial_base + FCR);       /* no fifo */
 151        outb(0x3, early_serial_base + MCR);     /* DTR + RTS */
 152
 153        if (*s) {
 154                baud = simple_strtoul(s, &e, 0);
 155                if (baud == 0 || s == e)
 156                        baud = DEFAULT_BAUD;
 157        }
 158
 159        divisor = 115200 / baud;
 160        c = inb(early_serial_base + LCR);
 161        outb(c | DLAB, early_serial_base + LCR);
 162        outb(divisor & 0xff, early_serial_base + DLL);
 163        outb((divisor >> 8) & 0xff, early_serial_base + DLH);
 164        outb(c & ~DLAB, early_serial_base + LCR);
 165}
 166
 167static struct console early_serial_console = {
 168        .name =         "earlyser",
 169        .write =        early_serial_write,
 170        .flags =        CON_PRINTBUFFER,
 171        .index =        -1,
 172};
 173
 174static inline void early_console_register(struct console *con, int keep_early)
 175{
 176        if (con->index != -1) {
 177                printk(KERN_CRIT "ERROR: earlyprintk= %s already used\n",
 178                       con->name);
 179                return;
 180        }
 181        early_console = con;
 182        if (keep_early)
 183                early_console->flags &= ~CON_BOOT;
 184        else
 185                early_console->flags |= CON_BOOT;
 186        register_console(early_console);
 187}
 188
 189static int __init setup_early_printk(char *buf)
 190{
 191        int keep;
 192
 193        if (!buf)
 194                return 0;
 195
 196        if (early_console)
 197                return 0;
 198
 199        keep = (strstr(buf, "keep") != NULL);
 200
 201        while (*buf != '\0') {
 202                if (!strncmp(buf, "serial", 6)) {
 203                        buf += 6;
 204                        early_serial_init(buf);
 205                        early_console_register(&early_serial_console, keep);
 206                        if (!strncmp(buf, ",ttyS", 5))
 207                                buf += 5;
 208                }
 209                if (!strncmp(buf, "ttyS", 4)) {
 210                        early_serial_init(buf + 4);
 211                        early_console_register(&early_serial_console, keep);
 212                }
 213                if (!strncmp(buf, "vga", 3) &&
 214                    boot_params.screen_info.orig_video_isVGA == 1) {
 215                        max_xpos = boot_params.screen_info.orig_video_cols;
 216                        max_ypos = boot_params.screen_info.orig_video_lines;
 217                        current_ypos = boot_params.screen_info.orig_y;
 218                        early_console_register(&early_vga_console, keep);
 219                }
 220#ifdef CONFIG_EARLY_PRINTK_DBGP
 221                if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
 222                        early_console_register(&early_dbgp_console, keep);
 223#endif
 224#ifdef CONFIG_HVC_XEN
 225                if (!strncmp(buf, "xen", 3))
 226                        early_console_register(&xenboot_console, keep);
 227#endif
 228#ifdef CONFIG_EARLY_PRINTK_INTEL_MID
 229                if (!strncmp(buf, "mrst", 4)) {
 230                        mrst_early_console_init();
 231                        early_console_register(&early_mrst_console, keep);
 232                }
 233
 234                if (!strncmp(buf, "hsu", 3)) {
 235                        hsu_early_console_init(buf + 3);
 236                        early_console_register(&early_hsu_console, keep);
 237                }
 238#endif
 239#ifdef CONFIG_EARLY_PRINTK_EFI
 240                if (!strncmp(buf, "efi", 3))
 241                        early_console_register(&early_efi_console, keep);
 242#endif
 243
 244                buf++;
 245        }
 246        return 0;
 247}
 248
 249early_param("earlyprintk", setup_early_printk);
 250