From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: [PATCH] rtc: rtc-at91sam9.c add DT support Date: Thu, 04 Apr 2013 09:25:42 -0400 Message-ID: <515D7F56.90702@interlog.com> References: <515CF985.6050009@interlog.com> <515D35C2.7050405@atmel.com> Reply-To: dgilbert@interlog.com Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <515D35C2.7050405@atmel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Nicolas Ferre Cc: Johan Hovold , Jean-Christophe PLAGNIOL-VILLARD , devicetree-discuss , linux-arm-kernel@lists.infradead.org, Robert Nelson List-Id: devicetree@vger.kernel.org On 13-04-04 04:11 AM, Nicolas Ferre wrote: > On 04/04/2013 05:54 AM, Douglas Gilbert : >> Some members of the at91 SoCs use the Real Time Timer (RTT) >> and the General Purpose Backup Registers (GPBR) to implement >> a real time clock (RTC). The AT91SAM9G20 is one example. >> >> Attached is a patch to add DT support to rtc-at91sam9.c . >> The patch is against lk 3.9.0-rc5 . >> >> Below is a snippet of DT code for the 'G20 that was observed >> to work with this patch: >> >> ahb { >> apb { >> >> rtc { >> compatible = "atmel,at91sam9-rtc"; > > The compatible string has to be formed by the name of the first SoC > compatible with this IP. It turns to be the at91sam9260. > The second part of the string should be a name that reflects the nature > of the peripheral. For this binding, I would like to mention the "RTT" > in the compatibility string (because other drivers can use other RTT > with other uses). > > What do you think about: > "atmel,at91sam9260-rtt-as-rtc"? or something shorter? Hi Nicolas, Johan Hovold suggested: atmel,at91sam9260-rtt I notice (in the G20 doco) that the acronym RTTC is also used for the rtt registers. What do you want? > >> /* RTTC followed by GPBR (backup registers) */ >> reg = <0xfffffd20 0x10>, <0xfffffd50 0x10>; >> interrupts = <1 4 7>; >> status = "okay"; > > Last, but not least, when we add a DT binding, it is a requirement to > add the corresponding documentation in the > Documentation/devicetree/bindings/rtc/ directory. I have been underwhelmed by the accuracy and the organisation of information in that documentation. And the examples are often misleading given the actual hierarchy of real dtsi/dts config files. Give me working examples any day. You could (and should) test what I gave on a g20ek board. Also I note there is no "bindings" documentation for rtc-at91rm9200.c :-) After you, sir .... Doug Gilbert