On Thu, Nov 05, 2015 at 07:11:52AM +0530, Viresh Kumar wrote:
> We may want to enable only a subset of OPPs, from the bigger list of
> OPPs, based on what version of the hardware we are running on. This
> would enable us to not duplicate OPP tables for every version of the
> hardware we support.
>
> To enable that, this patch defines a new property 'opp-supported-hw'. It
> can support any number of hierarchy levels of the versions the hardware
> follows. And based on the selected hardware versions, we can pick only
> the relevant OPPs at runtime.
>
> Reviewed-by: Stephen Boyd <sb...@codeaurora.org>
> Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
Acked-by: Rob Herring <r...@kernel.org>
> ---
> Documentation/devicetree/bindings/opp/opp.txt | 65
> +++++++++++++++++++++++++++
> 1 file changed, 65 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/opp/opp.txt
> b/Documentation/devicetree/bindings/opp/opp.txt
> index 0cb44dc21f97..d072fa0ffbd4 100644
> --- a/Documentation/devicetree/bindings/opp/opp.txt
> +++ b/Documentation/devicetree/bindings/opp/opp.txt
> @@ -123,6 +123,26 @@ properties.
> - opp-suspend: Marks the OPP to be used during device suspend. Only one OPP
> in
> the table should have this.
>
> +- opp-supported-hw: This enables us to select only a subset of OPPs from the
> + larger OPP table, based on what version of the hardware we are running on.
> We
> + still can't have multiple nodes with the same opp-hz value in OPP table.
> +
> + It's an user defined array containing a hierarchy of hardware version
> numbers,
> + supported by the OPP. For example: a platform with hierarchy of three
> levels
> + of versions (A, B and C), this field should be like <X Y Z>, where X
> + corresponds to Version hierarchy A, Y corresponds to version hierarchy B
> and Z
> + corresponds to version hierarchy C.
> +
> + Each level of hierarchy is represented by a 32 bit value, and so there can
> be
> + only 32 different supported version per hierarchy. i.e. 1 bit per version.
> A
> + value of 0xFFFFFFFF will enable the OPP for all versions for that hierarchy
> + level. And a value of 0x00000000 will disable the OPP completely, and so we
> + never want that to happen.
> +
> + If 32 values aren't sufficient for a version hierarchy, than that version
> + hierarchy can be contained in multiple 32 bit values. i.e. <X Y Z1 Z2> in
> the
> + above example, Z1 & Z2 refer to the version hierarchy Z.
> +
> - status: Marks the node enabled/disabled.
>
> Example 1: Single cluster Dual-core ARM cortex A9, switch DVFS states
> together.
> @@ -463,3 +483,48 @@ Example 5: Multiple OPP tables
> };
> };
> };
> +
> +Example 6: opp-supported-hw
> +(example: three level hierarchy of versions: cuts, substrate and process)
> +
> +/ {
> + cpus {
> + cpu@0 {
> + compatible = "arm,cortex-a7";
> + ...
> +
> + cpu-supply = <&cpu_supply>
> + operating-points-v2 = <&cpu0_opp_table_slow>;
> + };
> + };
> +
> + opp_table {
> + compatible = "operating-points-v2";
> + status = "okay";
> + opp-shared;
> +
> + opp00 {
> + /*
> + * Supports all substrate and process versions for 0xF
> + * cuts, i.e. only first four cuts.
> + */
> + opp-supported-hw = <0xF 0xFFFFFFFF 0xFFFFFFFF>
> + opp-hz = /bits/ 64 <600000000>;
> + opp-microvolt = <900000 915000 925000>;
> + ...
> + };
> +
> + opp01 {
> + /*
> + * Supports:
> + * - cuts: only one, 6th cut (represented by 6th bit).
> + * - substrate: supports 16 different substrate versions
> + * - process: supports 9 different process versions
> + */
> + opp-supported-hw = <0x20 0xff0000ff 0x0000f4f0>
> + opp-hz = /bits/ 64 <800000000>;
> + opp-microvolt = <900000 915000 925000>;
> + ...
> + };
> + };
> +};
> --
> 2.6.2.198.g614a2ac
>
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