Re: [PATCH] tty: serial: meson: Implement earlycon support
From: Peter Hurley <hidden>
Date: 2016-02-08 04:22:27
Also in:
linux-arm-kernel, lkml
Hi Andreas, On 02/07/2016 12:57 PM, Andreas Färber wrote:
quoted hunk ↗ jump to hunk
Reuse the existing console write implementation for implementing DT-based and command-line-based earlycon support. Signed-off-by: Andreas Färber <afaerber@suse.de> --- Documentation/kernel-parameters.txt | 6 ++++++ drivers/tty/serial/meson_uart.c | 13 +++++++++++++ 2 files changed, 19 insertions(+)diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 602065c..90801ac 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt@@ -1030,6 +1030,12 @@ Such letter suffixes can also be entirely omitted. the driver will use only 32-bit accessors to read/write the device registers. + meson_serial,<addr> + Start an early, polled-mode console on a meson serial + port at the specified address. The serial port must + already be setup and configured. Options are not yet + supported. + msm_serial,<addr> Start an early, polled-mode console on an msm serial port at the specified address. The serial portdiff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c index b12a37b..6f89567 100644 --- a/drivers/tty/serial/meson_uart.c +++ b/drivers/tty/serial/meson_uart.c@@ -548,6 +548,19 @@ static int __init meson_serial_console_init(void) } console_initcall(meson_serial_console_init); +static int __init +meson_serial_early_console_setup(struct earlycon_device *device, const char *opt) +{ + if (!device->port.membase) + return -ENODEV; + + device->con->write = meson_serial_console_write;
meson_serial_console_write() is not appropriate for earlycon; it assumes the earlycon port is the same as the driver port (it isn't).
+ return 0; +} +EARLYCON_DECLARE(meson_serial, meson_serial_early_console_setup); +OF_EARLYCON_DECLARE(meson_serial, "amlogic,meson-uart", + meson_serial_early_console_setup);
With today's linux-next (or Greg's tty-next tree), it is no longer necessary to declare separate earlycon's when you want both; OF_EARLYCON_DECLARE() declares both a devicetree-enabled earlycon and automatically provides for a command line earlycon of the same name. Regards, Peter Hurley
+ #define MESON_SERIAL_CONSOLE (&meson_serial_console) #else #define MESON_SERIAL_CONSOLE NULL