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Message-ID: <20250530135741.GA1598718-robh@kernel.org>
Date: Fri, 30 May 2025 08:57:41 -0500
From: Rob Herring <robh@...nel.org>
To: Kevin Hilman <khilman@...libre.com>
Cc: Ulf Hansson <ulf.hansson@...aro.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
arm-scmi@...r.kernel.org
Subject: Re: [PATCH RFC v2 2/2] pmdomain: core: use DT map to support
hierarchy
On Wed, May 28, 2025 at 02:58:52PM -0700, Kevin Hilman wrote:
> Currently, PM domains can only support hierarchy for simple
> providers (e.g. ones with #power-domain-cells = 0).
>
> Add support for oncell providers as well by adding support for a nexus
> node map, as described in section 2.5.1 of the DT spec.
>
> For example, an SCMI PM domain provider might be a subdomain of
> multiple parent domains. In this example, the parent domains are
> MAIN_PD and WKUP_PD:
>
> scmi_pds: protocol@11 {
> reg = <0x11>;
> #power-domain-cells = <1>;
> power-domain-map = <15 &MAIN_PD>,
> <19 &WKUP_PD>;
> };
>
> With the new map, child domain 15 (scmi_pds 15) becomes a
> subdomain of MAIN_PD, and child domain 19 (scmi_pds 19) becomes a
> subdomain of WKUP_PD.
>
> Signed-off-by: Kevin Hilman <khilman@...libre.com>
> ---
> drivers/pmdomain/core.c | 166 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 166 insertions(+)
>
> diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> index d6c1ddb807b2..b8e505516f3d 100644
> --- a/drivers/pmdomain/core.c
> +++ b/drivers/pmdomain/core.c
> @@ -2441,6 +2441,9 @@ static LIST_HEAD(of_genpd_providers);
> /* Mutex to protect the list above. */
> static DEFINE_MUTEX(of_genpd_mutex);
>
> +static int of_genpd_parse_domains_map(struct device_node *np,
> + struct genpd_onecell_data *data);
> +
> /**
> * genpd_xlate_simple() - Xlate function for direct node-domain mapping
> * @genpdspec: OF phandle args to map into a PM domain
> @@ -2635,6 +2638,14 @@ int of_genpd_add_provider_onecell(struct device_node *np,
> if (ret < 0)
> goto error;
>
> + /* Parse power-domains-map property for Nexus node mapping */
> + ret = of_genpd_parse_domains_map(np, data);
> + if (ret < 0 && ret != -ENOENT) {
> + pr_err("Failed to parse power-domains-map for %pOF: %d\n", np, ret);
> + of_genpd_del_provider(np);
> + goto error;
> + }
> +
> return 0;
>
> error:
> @@ -2734,6 +2745,161 @@ static struct generic_pm_domain *genpd_get_from_provider(
> return genpd;
> }
>
> +/**
> + * of_genpd_parse_domains_map() - Parse power-domains-map property for Nexus mapping
> + * @np: Device node pointer associated with the PM domain provider.
> + * @data: Pointer to the onecell data associated with the PM domain provider.
> + *
> + * Parse the power-domains-map property to establish parent-child relationships
> + * for PM domains using Nexus node mapping as defined in the device tree
> + * specification section v2.5.1.
> + *
> + * The power-domains-map property format is:
> + * power-domains-map = <child_specifier target_phandle [target_specifier]>, ...;
> + *
> + * Where:
> + * - child_specifier: The child domain ID that should be mapped
> + * - target_phandle: Phandle to the parent PM domain provider
> + * - target_specifier: Optional arguments for the parent provider (if it has #power-domain-cells > 0)
> + *
> + * Returns 0 on success, -ENOENT if property doesn't exist, or negative error code.
> + */
> +static int of_genpd_parse_domains_map(struct device_node *np,
> + struct genpd_onecell_data *data)
> +{
> + struct of_phandle_args parent_args;
> + struct generic_pm_domain *parent_genpd, *child_genpd;
> + u32 *map_entries;
> + int map_len, child_cells, i, ret;
> + u32 child_id;
> +
> + /* Check if power-domains-map property exists */
> + map_len = of_property_count_u32_elems(np, "power-domains-map");
> + if (map_len <= 0)
> + return -ENOENT;
Don't implement your own map parsing. Use or extend
of_parse_phandle_with_args_map().
Rob
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