+
+static void early_serial_init(int baud)
+{
+ unsigned char c;
+ unsigned divisor;
+
+ outb(0x3, early_serial_base + LCR); /* 8n1 */
+ outb(0, early_serial_base + IER); /* no interrupt */
+ outb(0, early_serial_base + FCR); /* no fifo */
+ outb(0x3, early_serial_base + MCR); /* DTR + RTS */
+
+ divisor = 115200 / baud;
+ c = inb(early_serial_base + LCR);
+ outb(c | DLAB, early_serial_base + LCR);
+ outb(divisor & 0xff, early_serial_base + DLL);
+ outb((divisor >> 8) & 0xff, early_serial_base + DLH);
+ outb(c & ~DLAB, early_serial_base + LCR);
+}
+
+void console_init(void)
+{
+ int baud = DEFAULT_BAUD;
+ char arg[32];
+ int pos = 0;
+
+ if (cmdline_find_option("earlyprintk", arg, sizeof arg) > 0) {
+ char *e;
+
+ if (!strncmp(arg, "serial", 6)) {
+ early_serial_base = DEFAULT_SERIAL_PORT;
+ pos += 6;
+ }
+
+ if (arg[pos] == ',')
+ pos++;
+
+ if (!strncmp(arg, "ttyS", 4)) {
+ static const int bases[] = { 0x3f8, 0x2f8 };
+ int port = 0;
+
+ if (!strncmp(arg + pos, "ttyS", 4))
+ pos += 4;
+
+ if (arg[pos++] == '1')
+ port = 1;
+
+ early_serial_base = bases[port];
+ }
+
+ if (arg[pos] == ',')
+ pos++;
+
+ baud = simple_strtoull(arg + pos, &e, 0);
+ if (baud == 0 || arg + pos == e)
+ baud = DEFAULT_BAUD;
+ }
+
+ if (early_serial_base != 0)
+ early_serial_init(baud);
+}