diff options
Diffstat (limited to 'arch/x86/boot/tty.c')
| -rw-r--r-- | arch/x86/boot/tty.c | 59 |
1 files changed, 58 insertions, 1 deletions
diff --git a/arch/x86/boot/tty.c b/arch/x86/boot/tty.c index f3ceee20ff1..f6d52e65f97 100644 --- a/arch/x86/boot/tty.c +++ b/arch/x86/boot/tty.c @@ -170,7 +170,7 @@ static void early_serial_init(int baud) outb(c & ~DLAB, early_serial_base + LCR); } -void console_init(void) +static int parse_earlyprintk(void) { int baud = DEFAULT_BAUD; char arg[32]; @@ -208,6 +208,63 @@ void console_init(void) baud = DEFAULT_BAUD; } + return baud; +} + +#define BASE_BAUD (1843200/16) +static unsigned int probe_baud(int port) +{ + unsigned char lcr, dll, dlh; + unsigned int quot; + + lcr = inb(port + LCR); + outb(lcr | DLAB, port + LCR); + dll = inb(port + DLL); + dlh = inb(port + DLH); + outb(lcr, port + LCR); + quot = (dlh << 8) | dll; + + return BASE_BAUD / quot; +} + +static int parse_console_uart8250(void) +{ + char optstr[64], *options; + int baud = DEFAULT_BAUD; + + /* + * console=uart8250,io,0x3f8,115200n8 + * need to make sure it is last one console ! + */ + if (cmdline_find_option("console", optstr, sizeof optstr) <= 0) + return baud; + + options = optstr; + + if (!strncmp(options, "uart8250,io,", 12)) + early_serial_base = simple_strtoull(options + 12, &options, 0); + else if (!strncmp(options, "uart,io,", 8)) + early_serial_base = simple_strtoull(options + 8, &options, 0); + else + return baud; + + if (options && (options[0] == ',')) + baud = simple_strtoull(options + 1, &options, 0); + else + baud = probe_baud(early_serial_base); + + return baud; +} + +void console_init(void) +{ + int baud; + + baud = parse_earlyprintk(); + + if (!early_serial_base) + baud = parse_console_uart8250(); + if (early_serial_base != 0) early_serial_init(baud); } |