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| author | Peter Hurley <peter@hurleysoftware.com> | 2015-04-06 10:52:39 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-04-10 14:39:54 +0200 |
| commit | ca782f16ce02e3f4fa2ae28a5ff256ac69f731e2 (patch) | |
| tree | 98efd55132080341b4d2dd4ad96fc24a99afdc71 | |
| parent | 87515772c33ee8a0cc08d984a7d2401eeff074cd (diff) | |
| download | linux-ca782f16ce02e3f4fa2ae28a5ff256ac69f731e2.tar.gz linux-ca782f16ce02e3f4fa2ae28a5ff256ac69f731e2.tar.xz | |
earlycon: 8250: Document kernel command line options
Document the expected behavior of kernel command lines of the forms:
console=uart[8250],io|mmio|mmio32,<addr>[,options]
console=uart[8250],<addr>[,options]
and
earlycon=uart[8250],io|mmio|mmio32,<addr>[,options]
earlycon=uart[8250],<addr>[,options]
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | Documentation/kernel-parameters.txt | 18 | ||||
| -rw-r--r-- | drivers/tty/serial/8250/8250_core.c | 5 |
2 files changed, 18 insertions, 5 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index bfcb1a62a7b4..1facf0bebb31 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 18142ee3c013..422ebea96a64 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -3471,12 +3471,13 @@ 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) + * If no <options> are specified, then assume the h/w is already setup. * * Returns 0 if console matches; otherwise non-zero to use default matching */ |