Hi Andreas,
On 02/07/2016 12:57 PM, Andreas Färber wrote:
> Reuse the existing console write implementation for implementing
> DT-based and command-line-based earlycon support.
>
> Signed-off-by: Andreas Färber <afaerber@xxxxxxx>
> ---
> 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 port
> diff --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
>
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