From mboxrd@z Thu Jan 1 00:00:00 1970 From: robin.murphy@arm.com (Robin Murphy) Date: Thu, 17 Mar 2016 19:21:23 +0000 Subject: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width property In-Reply-To: References: <1457005210-18485-1-git-send-email-narmstrong@baylibre.com> <1457519060-6038-1-git-send-email-narmstrong@baylibre.com> <1457519060-6038-3-git-send-email-narmstrong@baylibre.com> <20160317170926.GA28934@rob-hp-laptop> <56EAF212.7020700@arm.com> Message-ID: <56EB03B3.3070106@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 17/03/16 19:00, Rob Herring wrote: > On Thu, Mar 17, 2016 at 1:06 PM, Robin Murphy wrote: >> Hi Rob, >> >> On 17/03/16 17:09, Rob Herring wrote: >>> >>> On Wed, Mar 09, 2016 at 11:24:04AM +0100, Neil Armstrong wrote: >>>> >>>> Add timer-width optional property to specify a different vendor >>>> specific timer counter bit-width. >>>> >>>> Signed-off-by: Neil Armstrong >>>> --- >>>> Documentation/devicetree/bindings/timer/arm,sp804.txt | 2 ++ >>>> 1 file changed, 2 insertions(+) >>>> >>>> diff --git a/Documentation/devicetree/bindings/timer/arm,sp804.txt >>>> b/Documentation/devicetree/bindings/timer/arm,sp804.txt >>>> index 5cd8eee7..141e143 100644 >>>> --- a/Documentation/devicetree/bindings/timer/arm,sp804.txt >>>> +++ b/Documentation/devicetree/bindings/timer/arm,sp804.txt >>>> @@ -17,6 +17,8 @@ Optional properties: >>>> - arm,sp804-has-irq = <#>: In the case of only 1 timer irq line >>>> connected, this >>>> specifies if the irq connection is for timer 1 or timer 2. A >>>> value of 1 >>>> or 2 should be used. >>>> +- arm,timer-width: Should contain the width in number of bits of the >>>> counter, >>>> + is considered by default 32 but can be changed for vendor >>>> variants. >>> >>> >>> That would not be an SP804 nor would the vendor be ARM in that case. So >>> add a new compatible string for the vendor that decided to hack up ARM's >>> IP block. >> >> >> By all accounts this is some ancient reference design[1] which later evolved >> _into_ the SP804, so that vendor would probably still be ARM ;) > > Right. > >> A separate compatible string would indeed make more sense, though. Both >> semantically and in terms of letting the driver account for the differences >> automatically. >> >> Robin. >> >> [1]:http://infocenter.arm.com/help/topic/com.arm.doc.ddi0170a/I350250.html > > Humm, same as integrator timers perhaps? Having had a quick look, what the Integrator/AP manual describes certainly smells like the same basic block as the "AMBA Timer" - 16 bit counters and the same control register layout - albeit in a mutant triple-timer version with a bigger offset between each register set. Integrator/CP, on the other hand, looks much more SP804-like. Robin.