[PATCH 6/9] ARM: domain: Add platform handlers for CPU PM domains

[Lina Iyer]

On Wed, Aug 05 2015 at 08:45 -0600, Rob Herring wrote:
>On Tue, Aug 4, 2015 at 6:35 PM, Lina Iyer <lina.iyer at linaro.org> wrote:
>> In addition to the common power up/down actions of CPU PM domain core,
>> platforms may have additional configuration before the CPU domain can be
>> powered off or considered active. Allow platform drivers to register
>> handlers for CPU PM domains.
>>
>> Platform drivers may register their callbacks against a compatible
>> string defined by their PM domain provider device node in the DT. At
>> domain init, the platform driver can initialize the platform specific
>> genpd attributes. The init callback would need to return successfully,
>> for the platform power_on/off handlers to be registered with the CPU PM
>> domain.
>>
>> The code uses __init section to reduce memory needed for platform
>> handlers and therefore can be freed after the driver is initialized, a
>> desirable outcome for single kernel image.
>
>[...]
>
>> diff --git a/arch/arm/include/asm/arm-pd.h b/arch/arm/include/asm/arm-pd.h
>> new file mode 100644
>> index 0000000..fc44abf

[...]

>> +#define ARM_PD_METHOD_OF_DECLARE(_name, _handle, _ops) \
>> +       static const struct of_arm_pd_method __arm_pd_method_of_table_##_name \
>> +       __used __section(__arm_pd_method_of_table)              \
>> +       = { .handle = _handle, .ops = _ops }
>
>AFAICT, you are not using this in this series. You should add it when
>you have a user.
>
>Ideally, we keep some amount of uniformity across various *_OF_DECLARE
>which is why we have OF_DECLARE_1 and OF_DECLARE_2. This makes all the
>sections just arrays of struct of_device_id. Not all users follow
>this, but most do. So instead of putting the ops in here, platforms
>can provide a function callback which can then set the ops. Then you
>also don't need the .init() ops function as the callback function can
>do any initialization too.
>
I looked through these and I can switch over to _OF_DECLARE() without any
issues, but using OF_DECLARE_1 or OF_DECLARE_2 is pretty limiting.

If I could set up my own function type for the .data member, then its a
lot more easier on the code. Like this -

typedef int (*arm_pd_init)(struct device_node *dn, struct
		generic_pm_domain *genpd, struct of_arm_pd_ops *ops);

 #define ARM_PD_METHOD_OF_DECLARE(name, compat, fn)     \
	        _OF_DECLARE(arm_pd, name, compat, fn, arm_pd_init)

Its still in the of_device_id array.

Is that acceptable?

Thanks,
Lina