From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rob Herring <robherring2@gmail.com>
Subject: Re: [PATCH 03/23] ARM: u300: device tree support for the timer
Date: Fri, 26 Apr 2013 08:44:06 -0500
Message-ID: <517A84A6.4090108@gmail.com>
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To: Linus Walleij <linus.walleij@linaro.org>
Cc: Linus Walleij <linus.walleij@stericsson.com>, Arnd Bergmann <arnd@arndb.de>, "devicetree-discuss@lists.ozlabs.org" <devicetree-discuss@lists.ozlabs.org>, Rob Herring <rob.herring@calxeda.com>, Grant Likely <grant.likely@secretlab.ca>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
List-Id: devicetree@vger.kernel.org

On 04/26/2013 08:38 AM, Linus Walleij wrote:
> On Mon, Apr 22, 2013 at 1:36 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>> On Monday 22 April 2013, Linus Walleij wrote:
>>> +#ifdef CONFIG_OF
>>> +       struct device_node *timer = NULL;
>>> +
>>> +       timer = of_find_node_by_path("/timer0@c0014000");
>>> +       if (timer) {
>>> +               struct resource irq_res;
>>> +
>>> +               u300_timer_base = of_iomap(timer, 0);
>>> +               /* Get the IRQ for the GP1 timer */
>>> +               irq = of_irq_to_resource(timer, 2, &irq_res);
>>> +       }
>>> +#endif
>>
>> Do you need the #ifdef? The functions should be defined in a way that
>> removes this code if CONFIG_OF is not defined.
> 
> Actually not, this happens without CONFIG_OF:
> 
>   CC      arch/arm/mach-u300/timer.o
> /home/elinwal/linux-stericsson/arch/arm/mach-u300/timer.c: In function
> 'u300_timer_init':
> /home/elinwal/linux-stericsson/arch/arm/mach-u300/timer.c:371:2:
> error: implicit declaration of function 'of_find_node_by_path'
> [-Werror=implicit-function-declaration]
> /home/elinwal/linux-stericsson/arch/arm/mach-u300/timer.c:371:8:
> warning: assignment makes pointer from integer without a cast [enabled
> by default]
> /home/elinwal/linux-stericsson/arch/arm/mach-u300/timer.c:377:3:
> error: implicit declaration of function 'of_irq_to_resource'
> [-Werror=implicit-function-declaration]
> cc1: some warnings being treated as errors
> 
> make[3]: *** [arch/arm/mach-u300/timer.o] Error 1
> make[2]: *** [arch/arm/mach-u300] Error 2
> make[2]: *** Waiting for unfinished jobs....
> 
> Maybe it's just a bug that these don't have the proper stubs in <linux/of.h>?
> 
> Or is there a deeper idea behind this? (CC some OF ppl.)

Yes, you could add empty function, but searching by path is probably not
the right thing to do. Why not use clocksource_of_init? That's what all
the cool kids are doing now. Is there some special feature of the timer
at this address? If so, then add a property to describe that feature and
key off of that plus the compatible prop.

Rob

> 
> Yours,
> Linus Walleij
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