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.
Document the required behavior of the original implementation.
Reported-by: Yinghai Lu <ying...@kernel.org>
Signed-off-by: Peter Hurley <pe...@hurleysoftware.com>
---
v2: Fixed regression which allowed "console=uart1337,..." to start a
console (but not an earlycon)
+ fixed earlycon= documentation related required behavior fixed by
this patch
Documentation/kernel-parameters.txt | 18 +++++++++++++++---
drivers/tty/serial/8250/8250_core.c | 20 ++++++++++++++++++--
drivers/tty/serial/8250/8250_early.c | 19 -------------------
3 files changed, 33 insertions(+), 24 deletions(-)
diff --git a/Documentation/kernel-parameters.txt
b/Documentation/kernel-parameters.txt
index bfcb1a6..1facf0b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -713,10 +713,18 @@ bytes respectively. Such letter suffixes can also be
entirely omitted.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
+ uart[8250],mmio32,<addr>[,options]
+ uart[8250],0x<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address,
- switching to the matching ttyS device later. The
- options are the same as for ttyS, above.
+ switching to the matching ttyS device later.
+ MMIO inter-register address stride is either 8-bit
+ (mmio) or 32-bit (mmio32).
+ If none of [io|mmio|mmio32], <addr> is assumed to be
+ equivalent to 'mmio'. 'options' are specified in the
+ same format described for ttyS above; if unspecified,
+ the h/w is not re-initialized.
+
hvc<n> Use the hypervisor console device <n>. This is for
both Xen and PowerPC hypervisors.
@@ -944,11 +952,15 @@ bytes respectively. Such letter suffixes can also be
entirely omitted.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
uart[8250],mmio32,<addr>[,options]
+ uart[8250],0x<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address.
MMIO inter-register address stride is either 8-bit
(mmio) or 32-bit (mmio32).
- The options are the same as for ttyS, above.
+ If none of [io|mmio|mmio32], <addr> is assumed to be
+ equivalent to 'mmio'. 'options' are specified in the
+ same format described for "console=ttyS<n>"; if
+ unspecified, the h/w is not initialized.
pl011,<addr>
Start an early, polled-mode console on a pl011 serial
diff --git a/drivers/tty/serial/8250/8250_core.c
b/drivers/tty/serial/8250/8250_core.c
index e0fb5f0..bda2a57 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -3455,13 +3455,18 @@ static int univ8250_console_setup(struct console *co,
char *options)
* @options: ptr to option string from console command line
*
* Only attempts to match console command lines of the form:
- * console=uart<>,io|mmio|mmio32,<addr>,<options>
- * console=uart<>,<addr>,options
+ * console=uart[8250],io|mmio|mmio32,<addr>[,<options>]
+ * console=uart[8250],0x<addr>[,<options>]
* This form is used to register an initial earlycon boot console and
* replace it with the serial8250_console at 8250 driver init.
*
* Performs console setup for a match (as required by interface)
*
+ * ** HACK ALERT **
+ * If no <options> are specified, then assume the h/w is already setup.
+ * This was the undocumented behavior of the original implementation so
+ * it is cast in stone forever.
+ *
* Returns 0 if console matches; otherwise non-zero to use default matching
*/
static int univ8250_console_match(struct console *co, char *name, int idx,
@@ -3475,6 +3480,9 @@ static int univ8250_console_match(struct console *co,
char *name, int idx,
if (strncmp(name, match, 4) != 0)
return -ENODEV;
+ if (idx && idx != 8250)
+ return -ENODEV;
+
if (uart_parse_earlycon(options, &iotype, &addr, &options))
return -ENODEV;
@@ -3491,6 +3499,14 @@ static int univ8250_console_match(struct console *co,
char *name, int idx,
continue;
co->index = i;
+
+ /* if no line settings, then assume h/w was setup */
+ if (!options) {
+ /* link port to console */
+ port->cons = co;
+ return 0;
+ }
+
return univ8250_console_setup(co, options);
}
diff --git a/drivers/tty/serial/8250/8250_early.c
b/drivers/tty/serial/8250/8250_early.c
index e95ebfe..8e11968 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -105,21 +105,6 @@ static void __init early_serial8250_write(struct console
*console,
serial8250_early_out(port, UART_IER, ier);
}
-static unsigned int __init probe_baud(struct uart_port *port)
-{
- unsigned char lcr, dll, dlm;
- unsigned int quot;
-
- lcr = serial8250_early_in(port, UART_LCR);
- serial8250_early_out(port, UART_LCR, lcr | UART_LCR_DLAB);
- dll = serial8250_early_in(port, UART_DLL);
- dlm = serial8250_early_in(port, UART_DLM);
- serial8250_early_out(port, UART_LCR, lcr);
-
- quot = (dlm << 8) | dll;
- return (port->uartclk / 16) / quot;
-}
-
static void __init init_port(struct earlycon_device *device)
{
struct uart_port *port = &device->port;
@@ -151,10 +136,6 @@ static int __init early_serial8250_setup(struct
earlycon_device *device,
struct uart_port *port = &device->port;
unsigned int ier;
- device->baud = probe_baud(&device->port);
- snprintf(device->options, sizeof(device->options), "%u",
- device->baud);
-
/* assume the device was initialized, only mask interrupts */
ier = serial8250_early_in(port, UART_IER);
serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
--
2.3.5
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