redonkable/remarkable-linux
redonkable/remarkable-linux
1
0
Fork 0
Code Releases Activity

earlycon: 8250: Document kernel command line options

Browse source 
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>
This commit is contained in:
Peter Hurley 2015-04-06 10:52:39 -04:00 committed by Greg Kroah-Hartman
parent 87515772c3
commit ca782f16ce
2 changed files with 18 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

18
Documentation/kernel-parameters.txt
View file

@ -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

5
drivers/tty/serial/8250/8250_core.c
View file

@ -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
*/