diff options
Diffstat (limited to 'arch/x86/boot/tty.c')
| -rw-r--r-- | arch/x86/boot/tty.c | 111 |
1 files changed, 105 insertions, 6 deletions
diff --git a/arch/x86/boot/tty.c b/arch/x86/boot/tty.c index 01ec69c901c7..f3ceee20ff12 100644 --- a/arch/x86/boot/tty.c +++ b/arch/x86/boot/tty.c @@ -10,23 +10,51 @@ * ----------------------------------------------------------------------- */ /* - * Very simple screen I/O - * XXX: Probably should add very simple serial I/O? + * Very simple screen and serial I/O */ #include "boot.h" +#define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */ + +static int early_serial_base; + +#define XMTRDY 0x20 + +#define DLAB 0x80 + +#define TXR 0 /* Transmit register (WRITE) */ +#define RXR 0 /* Receive register (READ) */ +#define IER 1 /* Interrupt Enable */ +#define IIR 2 /* Interrupt ID */ +#define FCR 2 /* FIFO control */ +#define LCR 3 /* Line control */ +#define MCR 4 /* Modem control */ +#define LSR 5 /* Line Status */ +#define MSR 6 /* Modem Status */ +#define DLL 0 /* Divisor Latch Low */ +#define DLH 1 /* Divisor latch High */ + +#define DEFAULT_BAUD 9600 + /* * These functions are in .inittext so they can be used to signal * error during initialization. */ -void __attribute__((section(".inittext"))) putchar(int ch) +static void __attribute__((section(".inittext"))) serial_putchar(int ch) { - struct biosregs ireg; + unsigned timeout = 0xffff; - if (ch == '\n') - putchar('\r'); /* \n -> \r\n */ + while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) + cpu_relax(); + + outb(ch, early_serial_base + TXR); +} + +static void __attribute__((section(".inittext"))) bios_putchar(int ch) +{ + struct biosregs ireg; initregs(&ireg); ireg.bx = 0x0007; @@ -36,6 +64,17 @@ void __attribute__((section(".inittext"))) putchar(int ch) intcall(0x10, &ireg, NULL); } +void __attribute__((section(".inittext"))) putchar(int ch) +{ + if (ch == '\n') + putchar('\r'); /* \n -> \r\n */ + + bios_putchar(ch); + + if (early_serial_base != 0) + serial_putchar(ch); +} + void __attribute__((section(".inittext"))) puts(const char *str) { while (*str) @@ -112,3 +151,63 @@ int getchar_timeout(void) return 0; /* Timeout! */ } + +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); +} |