[PATCH v6 11/25] of: base: Add of_get_cpu_state_node() to get idle states for a CPU node

[Rob Herring]

On Wed, Mar 14, 2018 at 05:58:21PM +0100, Ulf Hansson wrote:
> The CPU's idle state nodes are currently parsed at the common cpuidle DT
> library, but also when initializing back-end data for the arch specific CPU
> operations, as in the PSCI driver case.
> 
> To avoid open-coding, let's introduce of_get_cpu_state_node(), which takes
> the device node for the CPU and the index to the requested idle state node,
> as in-parameters. In case a corresponding idle state node is found, it
> returns the node with the refcount incremented for it, else it returns
> NULL.
> 
> Moreover, for ARM, there are two generic methods, to describe the CPU's
> idle states, either via the flattened description through the
> "cpu-idle-states" binding [1] or via the hierarchical layout, using the
> "power-domains" and the "domain-idle-states" bindings [2]. Hence, let's
> take both options into account.
> 
> [1]
> Documentation/devicetree/bindings/arm/idle-states.txt
> [2]
> Documentation/devicetree/bindings/arm/psci.txt
> 
> Cc: Rob Herring <robh+dt at kernel.org>
> Cc: devicetree at vger.kernel.org
> Cc: Lina Iyer <ilina at codeaurora.org>
> Suggested-by: Sudeep Holla <sudeep.holla at arm.com>
> Co-developed-by: Lina Iyer <lina.iyer at linaro.org>
> Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
> ---
>  drivers/of/base.c  | 35 +++++++++++++++++++++++++++++++++++
>  include/linux/of.h |  8 ++++++++
>  2 files changed, 43 insertions(+)

I'd prefer not to add this here, but don't have a better suggestion. If 
more cpu related functions are added, I'd like to move them to a 
separate file in drivers/of/, but that can wait.

Reviewed-by: Rob Herring <robh at kernel.org>