From mboxrd@z Thu Jan  1 00:00:00 1970
From: leo.yan@linaro.org (Leo Yan)
Date: Sat, 26 Sep 2015 15:02:16 +0800
Subject: Debug UART for arm64 ?
In-Reply-To: <CAK7LNAQcBeQfRFf25HYOnN60rnb4uU=d=Ogas+-b1TCRMAxMJA@mail.gmail.com>
References: <CAK7LNAQcBeQfRFf25HYOnN60rnb4uU=d=Ogas+-b1TCRMAxMJA@mail.gmail.com>
Message-ID: <20150926070216.GA14835@leoy-linaro>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi,

On Sat, Sep 26, 2015 at 03:24:35PM +0900, Masahiro Yamada wrote:
> Forgive me if I am asking a silly question.
> 
> 
> I will have to port ARM64 Linux on our new SoC.
> This is my first work on ARM64 Linux,
> so I have no experience with it yet.
> 
> When I worked on ARM32 Linux porting for the first time,
> lowlevel-debug UART (CONFIG_DEBUG_LL) was very useful for me.
> 
> With my quick search under arch/arm64/ directory,
> I could not find an equivalent one for ARM64.
> 
> 
> Is debug UART available for ARM64?
> Or, is there any other recommended easy-to-use debug facility
> when something like a JTAG-debugger is unavailable.

drivers/tty/serial/earlycon.c is like what you are looking for.

Thanks,
Leo Yan