[PATCH v2 02/18] dt-bindings: timer: sp804: add timer-width property
robin.murphy at arm.com
Tue Mar 22 05:02:32 PDT 2016
On 22/03/16 09:21, Neil Armstrong wrote:
> On 03/17/2016 08:21 PM, Robin Murphy wrote:
>> On 17/03/16 19:00, Rob Herring wrote:
>>> On Thu, Mar 17, 2016 at 1:06 PM, Robin Murphy <robin.murphy at arm.com> wrote:
>>>> Hi Rob,
>>>> On 17/03/16 17:09, Rob Herring wrote:
>>>>> 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 which later evolved
>>>> _into_ the SP804, so that vendor would probably still be ARM ;)
>>>> A separate compatible string would indeed make more sense, though. Both
>>>> semantically and in terms of letting the driver account for the differences
>>> 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.
> I will switch to oxsemi,ox810se-rps-timer since it need a specific register width that will be handled by the driver.
By "needs a specific register width" do you mean the OxSemi
implementation will give a bus error on a 32-bit access and requires
16-bit accessors? If so, I'd expect to see patch 1 changing readl()s to
readw()s at least somewhere. Otherwise, if it's merely that the
clocksource API needs to know the upper 16 bits of a word it reads are
undefined, then since that's the standard behaviour I'd be inclined to
add it to the driver as a canonical "arm,amba-timer" implementation,
then have your implementation-specific compatible on top of that just in
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