Hi Mark,
 
 On mar., févr. 02 2016, Mark Rutland [off-list ref] wrote:

On Tue, Feb 02, 2016 at 07:07:39PM +0100, Gregory CLEMENT wrote:

quoted

From: Wilson Ding <redacted>

Armada-3700's uart is a simple serial port, which doesn't
support. Configuring the modem control lines. The uart port has a 32
bytes Tx FIFO and a 64 bytes Rx FIFO

The uart driver implements the uart core operations. It also support the
system (early) console based on Armada-3700's serial port.

Known Issue:

The uart driver currently doesn't support clock programming, which means
the baud-rate stays with the default value configured by the bootloader
at boot time

To ensure that the bootloader and kernel match, it's best to place the
rate in the stdout-path property (as in
Documentation/devicetree/bindings/chosen.txt).

Presumably that is what you want?

It is done in patch 7.

Is it difficutl to add clock programming?

Currently there is no clock tree support before adding it I would like
to be able to test it.

Thanks,

Gregory

quoted

[gregory.clement@free-electrons.com: Rewrite many part which are too long
to enumerate]

Signed-off-by: Wilson Ding <redacted>
Signed-off-by: Nadav Haklai <redacted>
Signed-off-by: Gregory CLEMENT <redacted>
---
 .../devicetree/bindings/tty/serial/mvebu-uart.txt  |  13 +
 Documentation/kernel-parameters.txt                |   6 +
 drivers/tty/serial/Kconfig                         |  22 +
 drivers/tty/serial/Makefile                        |   1 +
 drivers/tty/serial/mvebu-uart.c                    | 649 +++++++++++++++++++++
 include/uapi/linux/serial_core.h                   |   3 +
 6 files changed, 694 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/tty/serial/mvebu-uart.txt
 create mode 100644 drivers/tty/serial/mvebu-uart.c

diff --git a/Documentation/devicetree/bindings/tty/serial/mvebu-uart.txt b/Documentation/devicetree/bindings/tty/serial/mvebu-uart.txt
new file mode 100644
index 000000000000..6087defd9f93
--- /dev/null
+++ b/Documentation/devicetree/bindings/tty/serial/mvebu-uart.txt

@@ -0,0 +1,13 @@
+* Marvell UART : Non standard UART used in some of Marvell EBU SoCs (e.g., Armada-3700)
+
+Required properties:
+- compatible: "marvell,armada-3700-uart"
+- reg: offset and length of the register set for the device.
+- interrupts: device interrupt
+
+Example:
+	serial@12000 {
+		compatible = "marvell,armada-3700-uart";
+		reg = <0x12000 0x400>;
+		interrupts = <43>;
+	};

There are no external clock inputs?

quoted

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 87d40a72f6a1..198f6bd56e84 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt

@@ -1058,6 +1058,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			A valid base address must be provided, and the serial
 			port must already be setup and configured.
 
+		mvebu_uart,<addr>
+			Start an early, polled-mode console on an some mvebu
+			SoC (as the Armada-3700) serial port at the specified
+			address. The serial port must already be setup and
+			configured. Options are not yet supported.
+

Does the the mvebu UART vary between platforms at all?

Thanks,
Mark.

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com