[PATCH 1/2] Documentation: DT: Add entry for ARM SP805-WDT

[Bhupesh SHARMA]

Hi Mark,

Thanks for the review.

On Mon, Nov 16, 2015 at 8:15 PM, Mark Rutland <mark.rutland at arm.com> wrote:
> On Mon, Nov 16, 2015 at 07:54:42PM +0530, Bhupesh Sharma wrote:
>> This patch adds a devicetree binding documentation for ARM's
>> SP805 WatchDog Timer.
>>
>> Signed-off-by: Bhupesh Sharma <bhupesh.sharma at freescale.com>
>> ---
>>  .../devicetree/bindings/watchdog/sp805-wdt.txt     |   33 ++++++++++++++++++++
>>  1 file changed, 33 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>
>> diff --git a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>> new file mode 100644
>> index 0000000..ec70fe9
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>> @@ -0,0 +1,33 @@
>> +* ARM SP805 Watchdog Timer (WDT) Controller
>> +
>> +SP805 WDT is a ARM Primecell Peripheral and has a standard-id register that
>> +can be used to identify the peripheral type, vendor, and revision.
>> +This value can be used for driver matching.
>> +
>> +Note that the current sp805_wdt driver relies on the 'drivers/amba/bus.c'
>> +framework to invoke the probe function of the sp805_wdt driver using the
>> +unique PRIMECELL identifiers of the sp805 wdt IP.
>
> This paragraph can go. We shouldn't describe kernel internals.

Ok.

>> +As SP805 WDT is a primecell IP, it follows the base bindings specified in
>> +'arm/primecell.txt'
>> +
>> +Required properties:
>> +- compatible : Should be "arm,sp805-wdt", "arm,primecell"
>> +- reg : Base address and size of the watchdog timer registers.
>> +- interrupts : Should specify WDT interrupt number.
>> +
>> +Optional properties:
>> +- clocks : From common clock binding. First clock is phandle to clock for apb
>> +           pclk. Additional clocks are optional.
>> +- clock-names : From common clock binding. Shall be "apb_pclk" for first clock.
>
> The hardware has "WDOGCLK", which is what the driver appears to expect
> first implicitly.

Ok.

>> +Examples:
>> +
>> +             cluster1_core0_watchdog: wdt at c000000 {
>> +                     compatible = "arm,sp805-wdt", "arm,primecell";
>> +                     reg = <0x0 0xc000000 0x0 0x1000>;
>> +                     interrupts = <1 12 0x8>; /* PPI, Level low type */
>
> I don't see how you can use PPIs here. This is not banked per CPU.

I have raised this concern to my hardware team. This might be an issue
with the documentation.
I will change it in v2 as per their comments.

Regards,
Bhupesh

> Mark.
>
>> +                     clocks = <&clockgen 4 3>;
>> +                     clock-names = "apb_pclk";
>> +             };
>> +
>> --
>> 1.7.9.5
>>
>>