linux-kernel - Re: [RFC 17/17] clk: zynq: remove call to of_clk

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Date:	Mon, 26 Aug 2013 08:16:29 -0700
From:	Sören Brinkmann <soren.brinkmann@...inx.com>
To:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
CC:	Steffen Trumtrar <s.trumtrar@...gutronix.de>,
	Michal Simek <monstr@...str.eu>,
	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>,
	Michal Simek <michal.simek@...inx.com>,
	<linux-kernel@...r.kernel.org>,
	Mike Turquette <mturquette@...aro.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC 17/17] clk: zynq: remove call to of_clk_init

On Mon, Aug 26, 2013 at 02:53:35PM +0200, Sebastian Hesselbarth wrote:
> On 08/26/13 14:07, Steffen Trumtrar wrote:
> >On Mon, Aug 26, 2013 at 01:15:11PM +0200, Michal Simek wrote:
> >>I agree with Soren - let's fix the current problem and then when Steffen has patches with syscon
> >>we can look at them.
> >>
> >>If there is any discussion about early syscon registration please let me know.
> >>
> >
> >Where I'm stuck at the moment is: if I map the whole register space to the
> >parent node, how do I get its mapped address in the clkc?
> 
> Steffen,
> 
> if slcr is such an essential part of the SoC, you can choose to provide
> zynq_slcr_readl/writel callbacks. You can then use those callback in the
> clock driver without knowing the base address. Also, it allows you to
> hide slcr specific locking details from subsequent drivers using the
> callbacks.

I don't think that'll work. The clkc just wraps the cock primitives and
does not provide a lot of own clock drivers - actually only one. Those
clock primitives receive an iomapped address for the clock control which
is then accessed using readl/writel(). So, wrapping all SLCR accesses in
special accessors would mean to have almost identical reimplementations
of all used clock primitives, just to replace readl/writel with
zynq_slcr_write/read. Or is there some way to make this actually work?


Sören


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