Re: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width property

From	Robin Murphy <robin.murphy@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width property
Date	2016-03-17 20:30 +0100
Message-ID	<rdLMm-32d-3@gated-at.bofh.it> (permalink)
References	(1 earlier) <raJxn-6vl-5@gated-at.bofh.it> <raJxo-6vl-31@gated-at.bofh.it> <rdJAS-1Mf-7@gated-at.bofh.it> <rdKwY-2ml-45@gated-at.bofh.it> <rdLt0-2VH-17@gated-at.bofh.it>
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On 17/03/16 19:00, Rob Herring wrote:
> On Thu, Mar 17, 2016 at 1:06 PM, Robin Murphy <robin.murphy@arm.com> 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 <narmstrong@baylibre.com>
>>>> ---
>>>>    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.

Thread

[PATCH v2 00/18] Add Initial support for PLX Technology OX810SE Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
  [PATCH v2 03/18] irqchip: versatile-fpga: add new arm,rps-irq compatible Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
    Re: [PATCH v2 03/18] irqchip: versatile-fpga: add new arm,rps-irq  compatible Marc Zyngier <marc.zyngier@arm.com> - 2016-03-15 12:50 +0100
  [PATCH v2 18/18] arm: boot: dts: Add Western Digital My Book World Edition device tree Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
  [PATCH v2 08/18] dt-bindings: Add PLX Technology Reset Controller bindings Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
    Re: [PATCH v2 08/18] dt-bindings: Add PLX Technology Reset  Controller bindings Rob Herring <robh@kernel.org> - 2016-03-17 18:20 +0100
  [PATCH v2 13/18] arm: Add new mach-oxnas Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
  [PATCH v2 07/18] reset: Add PLX Technology Reset Controller driver Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
  [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width property Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
    Re: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width  property Rob Herring <robh@kernel.org> - 2016-03-17 18:10 +0100
      Re: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width  property Robin Murphy <robin.murphy@arm.com> - 2016-03-17 19:10 +0100
        Re: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width property Rob Herring <robh@kernel.org> - 2016-03-17 20:10 +0100
          Re: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width  property Robin Murphy <robin.murphy@arm.com> - 2016-03-17 20:30 +0100
            Re: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width  property Neil Armstrong <narmstrong@baylibre.com> - 2016-03-22 10:30 +0100
              Re: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width  property Robin Murphy <robin.murphy@arm.com> - 2016-03-22 13:10 +0100
                Re: [PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width  property Neil Armstrong <narmstrong@baylibre.com> - 2016-03-22 15:40 +0100
  [PATCH v2 14/18] arm: Add build support for mach-oxnas Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
  [PATCH v2 06/18] dt-bindings: Add Oxford Semiconductors to vendor prefixes Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
    Re: [PATCH v2 06/18] dt-bindings: Add Oxford Semiconductors to  vendor prefixes Rob Herring <robh@kernel.org> - 2016-03-17 18:20 +0100
  [PATCH v2 04/18] dt-bindings: irq: arm,versatile-fpga: add arm,rps-irq compatible string Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
    Re: [PATCH v2 04/18] dt-bindings: irq: arm,versatile-fpga: add  arm,rps-irq compatible string Rob Herring <robh@kernel.org> - 2016-03-17 18:20 +0100
  [PATCH v2 01/18] clocksource: sp804: Add support for non-32bit width counter Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100
    Re: [PATCH v2 01/18] clocksource: sp804: Add support for non-32bit  width counter Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-03-17 17:50 +0100
  [PATCH v2 17/18] dt-bindings: Add Western Digital to vendor prefixes Neil Armstrong <narmstrong@baylibre.com> - 2016-03-09 11:30 +0100

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