diff options
| author | Doug Anderson <dianders@chromium.org> | 2011-09-22 13:16:57 -0700 |
|---|---|---|
| committer | Doug Anderson <dianders@chromium.org> | 2011-09-23 15:56:08 -0700 |
| commit | 16581e0aab24f8457e7ec803e35659b06b1ab9f9 (patch) | |
| tree | 2b5a440a05bd4d3e89c49caae8501648d2145f18 /drivers | |
| parent | a5049abf85217d6da4bb725d59ddfe018beea6b3 (diff) | |
CHROMIUM: arm: Specify debugging serial port at boot.
This works together with a kernel change that looks at
the scratchpad register to determine which of the many
UARTs it should use for early printing:
<http://gerrit.chromium.org/gerrit/8148>. While it is
unfortunate to need to pass this information in a
second way (it's already in the device tree), this
does allow the very early boot code (decompressing stub
and early assembly code) to print to the right port.
At the moment, I'm adding this to the UART init function.
Alternatively, we could add a more complex patch to
key off of the 'console' setting.
BUG=chromium-os:19656
TEST=See <http://gerrit.chromium.org/gerrit/8148>
Change-Id: Iea374625f22b9fa64cf22820dfd530eca1c38bb0
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-on: http://gerrit.chromium.org/gerrit/8156
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/serial/ns16550.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c index 04217de3db..8b45106a53 100644 --- a/drivers/serial/ns16550.c +++ b/drivers/serial/ns16550.c @@ -69,6 +69,12 @@ void NS16550_init (NS16550_t com_port, int baud_divisor) serial_out(baud_divisor & 0xff, &com_port->dll); serial_out((baud_divisor >> 8) & 0xff, &com_port->dlm); serial_out(UART_LCRVAL, &com_port->lcr); + + /* + * Put a 'D' in the scratchpad to let the kernel know which UART + * for earlyprintk [D]ebugging. + */ + serial_out('D', &com_port->spr); #if defined(CONFIG_OMAP) && !defined(CONFIG_OMAP3_ZOOM2) #if defined(CONFIG_APTIX) serial_out(3, &com_port->mdr1); /* /13 mode so Aptix 6MHz can hit 115200 */ |