linux-kernel - Re: [PATCHv1] rtc: bcm-iproc: Add support for Broadcom iproc rtc

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Message-ID: <1418783023.hzNZBNCmFc@wuerfel>
Date:	Tue, 16 Dec 2014 21:19:05 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	Arun Ramamurthy <arun.ramamurthy@...adcom.com>,
	mark.rutland@....com, a.zummo@...ertech.it, sbranden@...adcom.com,
	pawel.moll@....com, devicetree@...r.kernel.org, rjui@...adcom.com,
	ijc+devicetree@...lion.org.uk,
	Arun Ramamurthy <arunrama@...adcom.com>,
	linux-kernel@...r.kernel.org, grant.likely@...aro.org,
	robh+dt@...nel.org, bcm-kernel-feedback-list@...adcom.com,
	galak@...eaurora.org, rtc-linux@...glegroups.com
Subject: Re: [PATCHv1] rtc: bcm-iproc: Add support for Broadcom iproc rtc

On Tuesday 16 December 2014 12:05:08 Arun Ramamurthy wrote:
> On 14-12-16 11:42 AM, Arnd Bergmann wrote:
> > On Tuesday 16 December 2014 11:22:30 arun.ramamurthy@...adcom.com wrote:
> >> +       rtc: iproc_rtc@...3026000 {
> >> +               compatible = "brcm,iproc-rtc";
> >> +               reg =   spru_bbl:               <0x03026000 0xC>,
> >> +                       crmu_pwr_good_status:   <0x0301C02C 0x14>,
> >> +                       crmu_bbl_auth:          <0x03024C74 0x8>;
> >> +               interrupts = spru_rtc_periodic: <GIC_SPI 142 IRQ_TYPE_LEVEL_HIGH>,
> >> +                            spru_alarm:        <GIC_SPI 133 IRQ_TYPE_LEVEL_HIGH>;
> >
> > The reg properties look really random, could it be that the registers
> > are really part of some other device that contains multiple functions?
> >
> This RTC block is on a battery backed logic island and is accessed 
> indirectly using the spru_bbl registers. The CRMU registers are required 
> to read the power status and write to some authentication registers. 
> Without writing to these authentication
> registers, we cannot access any of the spru_bbl registers. In conclusion
> I don't think the CRMU register accesses can be considered as another 
> device access. Do you agree Arnd?

It sounds like CRMU is some other unit aside from the RTC. Could this
be something like a generic system controller? I think it should
either have its own driver or use the syscon logic if that is what
this is.

> > Also, what do you use the labels for?
> >
> The labels are purely to improve readability of the device tree entry

Please remove them then, they don't help at all.

	Arnd
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