Re: [PATCH 01/10] serial: mvebu-uart: initial support for Armada-3700 serial port

From: Gregory CLEMENT <gregory.clement@free-electrons.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Jason Cooper <jason@lakedaemon.net>, Andrew Lunn <andrew@lunn.ch>,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
	arm@kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	linux-serial@vger.kernel.org, Tejun Heo <tj@kernel.org>,
	Hans de Goede <hdegoede@redhat.com>,
	linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org,
	Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
	linux-arm-kernel@lists.infradead.org,
	Wilson Ding <dingwei@marvell.com>,
	Nadav Haklai <nadavh@marvell.com>
Subject: Re: [PATCH 01/10] serial: mvebu-uart: initial support for Armada-3700 serial port
Date: Wed, 03 Feb 2016 17:56:56 +0100	[thread overview]
Message-ID: <87egct4trb.fsf@free-electrons.com> (raw)
In-Reply-To: <20160202182842.GD29778@leverpostej> (Mark Rutland's message of "Tue, 2 Feb 2016 18:28:42 +0000")

Hi Mark,

 On mar., févr. 02 2016, Mark Rutland <mark.rutland@arm.com> wrote:

>> 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?

Right, even if we don't use it in the driver we should ad it in the
binding because there is an external clock input.

>
>> 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?

I am not sure to undersatnd your question.

If you asked about the UART used on the other mvebu SoCs then my answer
is: on all the other mvebu SoC until now third party IPs were used. This
one is the first one dedicated to an mevbu SoC and currently only used
on Armada 3700 but I don't know what are the plan for the future mvebu
SoCs.

Gregory

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