On Mon, 2014-03-03 at 05:02PM +0100, Tomasz Figa wrote:
> This patch introduces generic code to perform power domain look-up using
> device tree and automatically bind devices to their power domains.
> Generic device tree binding is introduced to specify power domains of
> devices in their device tree nodes.
>
> Backwards compatibility with legacy Samsung-specific power domain
> bindings is provided, but for now the new code is not compiled when
> CONFIG_ARCH_EXYNOS is selected to avoid collision with legacy code. This
> will change as soon as Exynos power domain code gets converted to use
> the generic framework in further patch.
>
> Signed-off-by: Tomasz Figa <tomasz.figa@xxxxxxxxx>
> ---
> .../devicetree/bindings/power/power_domain.txt | 51 ++++
> drivers/base/power/domain.c | 298 +++++++++++++++++++++
> include/linux/pm_domain.h | 46 ++++
> kernel/power/Kconfig | 4 +
> 4 files changed, 399 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/power/power_domain.txt
>
> diff --git a/Documentation/devicetree/bindings/power/power_domain.txt b/Documentation/devicetree/bindings/power/power_domain.txt
> new file mode 100644
> index 0000000..93be5d9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/power_domain.txt
> @@ -0,0 +1,51 @@
> +* Generic power domains
> +
> +System on chip designs are often divided into multiple power domains that
> +can be used for power gating of selected IP blocks for power saving by
> +reduced leakage current.
> +
> +This device tree binding can be used to bind power domain consumer devices
> +with their power domains provided by power domain providers. A power domain
> +provider can be represented by any node in the device tree and can provide
> +one or more power domains. A consumer node can refer to the provider by
> +a phandle and a set of phandle arguments (so called power domain specifier)
> +of length specified by #power-domain-cells property in the power domain
> +provider node.
> +
> +==Power domain providers==
> +
> +Required properties:
> + - #power-domain-cells : Number of cells in a power domain specifier;
> + Typically 0 for nodes representing a single power domain and 1 for nodes
> + providing multiple power domains (e.g. power controllers), but can be
> + any value as specified by device tree binding documentation of particular
> + provider.
> +
> +Example:
> +
> + power: power-controller@12340000 {
> + compatible = "foo,power-controller";
> + reg = <0x12340000 0x1000>;
> + #power-domain-cells = <1>;
> + };
> +
> +The node above defines a power controller that is a power domain provider
> +and expects one cell as its phandle argument.
> +
> +==Power domain consumers==
> +
> +Required properties:
> + - power-domain : A phandle and power domain specifier as defined by bindings
> + of power controller specified by phandle.
> +
> +Example:
> +
> + leaky-device@12350000 {
> + compatible = "foo,i-leak-current";
> + reg = <0x12350000 0x1000>;
> + power-domain = <&power 0>;
> + };
> +
> +The node above defines a typical power domain consumer device, which is located
> +inside power domain with index 0 of power controller represented by node with
> +label "power".
Does this allow nesting of power domains? E.g. you have a PD which is
represented by some programmable power supply, and within this domain
smaller islands/domains that can be gated independently.
Thanks,
Sören
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