Hi Peter,

Am 08.02.2016 um 05:22 schrieb Peter Hurley:

On 02/07/2016 12:57 PM, Andreas F?rber wrote:

quoted

Reuse the existing console write implementation for implementing
DT-based and command-line-based earlycon support.

Signed-off-by: Andreas F?rber <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 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).

Thanks for spotting that.

I forgot to mention that I tested this on arm64, where there is no
earlyprintk any more, seemingly successfully getting a bootconsole
uart0. Using co->data instead of co->index I now get meson_serial0
instead, doh.

This probably slipped though because another patch is necessary for
fixing the baudrate calculation on my device.

quoted

+	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.

Thanks for the hint, it was based on linux-next from a couple days ago.

Is there any guidance wrt naming? I noticed that msm uses -uart in the
compatible string and _serial for earlycon, so I copied that; should it
rather be meson_uart or just meson?

Regards,
Andreas

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