earlycon: 8250: Fix command line regression

Restore undocumented behavior of kernel command line parameters of
the forms:
    console=uart[8250],io|mmio|mmio32,<addr>[,options]
    console=uart[8250],<addr>[,options]
where 'options' have not been specified; in this case, the hardware
is assumed to be initialized.

Fixes: c7cef0a84912cab3c9df8 ("console: Add extensible console matching")
Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index e0fb5f0..18142ee 100644 (file)
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -3412,9 +3412,23 @@ static void univ8250_console_write(struct console *co, const char *s,
        serial8250_console_write(up, s, count);
 }
 
-static int serial8250_console_setup(struct uart_8250_port *up, char *options)
+static unsigned int probe_baud(struct uart_port *port)
+{
+       unsigned char lcr, dll, dlm;
+       unsigned int quot;
+
+       lcr = serial_port_in(port, UART_LCR);
+       serial_port_out(port, UART_LCR, lcr | UART_LCR_DLAB);
+       dll = serial_port_in(port, UART_DLL);
+       dlm = serial_port_in(port, UART_DLM);
+       serial_port_out(port, UART_LCR, lcr);
+
+       quot = (dlm << 8) | dll;
+       return (port->uartclk / 16) / quot;
+}
+
+static int serial8250_console_setup(struct uart_port *port, char *options, bool probe)
 {
-       struct uart_port *port = &up->port;
        int baud = 9600;
        int bits = 8;
        int parity = 'n';
@@ -3425,13 +3439,15 @@ static int serial8250_console_setup(struct uart_8250_port *up, char *options)
 
        if (options)
                uart_parse_options(options, &baud, &parity, &bits, &flow);
+       else if (probe)
+               baud = probe_baud(port);
 
        return uart_set_options(port, port->cons, baud, parity, bits, flow);
 }
 
 static int univ8250_console_setup(struct console *co, char *options)
 {
-       struct uart_8250_port *up;
+       struct uart_port *port;
 
        /*
         * Check whether an invalid uart number has been specified, and
@@ -3440,11 +3456,11 @@ static int univ8250_console_setup(struct console *co, char *options)
         */
        if (co->index >= nr_uarts)
                co->index = 0;
-       up = &serial8250_ports[co->index];
+       port = &serial8250_ports[co->index].port;
        /* link port to console */
-       up->port.cons = co;
+       port->cons = co;
 
-       return serial8250_console_setup(up, options);
+       return serial8250_console_setup(port, options, false);
 }
 
 /**
@@ -3491,7 +3507,8 @@ static int univ8250_console_match(struct console *co, char *name, int idx,
                        continue;
 
                co->index = i;
-               return univ8250_console_setup(co, options);
+               port->cons = co;
+               return serial8250_console_setup(port, options, true);
        }
 
        return -ENODEV;

diff --cc drivers/tty/serial/8250/8250_early.c
Simple merge