From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-qt0-f173.google.com ([209.85.216.173]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bQRls-0000lS-P0 for kexec@lists.infradead.org; Fri, 22 Jul 2016 04:09:09 +0000 Received: by mail-qt0-f173.google.com with SMTP id u25so55563069qtb.1 for ; Thu, 21 Jul 2016 21:08:47 -0700 (PDT) Date: Fri, 22 Jul 2016 09:38:42 +0530 From: Pratyush Anand Subject: Re: [PATCH v1 3/4] arm64: Add arm64 kexec support Message-ID: <20160722040842.GA14911@localhost.localdomain> References: <9ed513fd44a19b2f49b4da99477cedfff7341bf0.1468970114.git.geoff@infradead.org> <20160720153859.GG24691@leverpostej> <1469042361.2977.90.camel@infradead.org> <20160721103120.GB20559@leverpostej> <5790A902.6070601@arm.com> <1469137776.2977.128.camel@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1469137776.2977.128.camel@infradead.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Geoff Levand Cc: Mark Rutland , kexec@lists.infradead.org, AKASHI Takahiro , Simon Horman , Robin Murphy , linux-arm-kernel@lists.infradead.org On 21/07/2016:02:49:36 PM, Geoff Levand wrote: > On Thu, 2016-07-21 at 11:50 +0100, Robin Murphy wrote: > > The Exynos UART (drivers/tty/serial/samsung.c) is one which comes to > > mind as definitely existing, and on arm64 systems to boot. The TX > > register is at offset 0x20 there. > > Here's what I came up with. > > > + struct data {const char *name; int tx_offset;}; > + static const struct data ok_list[] = { > + /* {"armada-3700-uart", ?}, */ > + {"exynos4210-uart", 0x20}, > + /* {"ls1021a-lpuart", ?}, */ > + /* {"meson-uart", ?}, */ > + /* {"mt6577-uart", ?}, */ > + {"ns16550", 0}, > + {"ns16550a", 0}, > + {"pl011", 0}, > + {NULL, 0} > + }; sinc functionality is just to debug the scenario when something goes wrong in purgatory. IMHO, it should be disabled by default. So, why not to keep it as simple as possible. Its a low level debugging mainly for developer, so user should know the absolute address. Therefore, I think no need to parse earlycon or earlyprintk from command line. Whatever user passes in --port can be treated as address of TX register. If TX offset is 0x20, then user can pass --port as base+0x20. Additionally, we can pass TX register width as well. So what about something like "--port=0x1c020000,1" where 0x1c020000 is TX register address and 1 says about it's width in bytes. ~Pratyush _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec