// SPDX-License-Identifier: GPL-2.0
/*
 * PM domains for CPUs via genpd - managed by cpuidle-psci.
 *
 * Copyright (C) 2019 Linaro Ltd.
 * Author: Ulf Hansson <ulf.hansson@linaro.org>
 *
 */

#define pr_fmt(fmt) "CPUidle PSCI: " fmt

#include <linux/cpu.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>
#include <linux/psci.h>
#include <linux/slab.h>
#include <linux/string.h>

#include "cpuidle-psci.h"
#include "dt_idle_genpd.h"

struct psci_pd_provider {
        struct list_head link;
        struct device_node *node;
};

static LIST_HEAD(psci_pd_providers);

static int psci_pd_power_off(struct generic_pm_domain *pd)
{
        struct genpd_power_state *state = &pd->states[pd->state_idx];
        u32 *pd_state;

        if (!state->data)
                return 0;

        /* OSI mode is enabled, set the corresponding domain state. */
        pd_state = state->data;
        psci_set_domain_state(pd, pd->state_idx, *pd_state);

        return 0;
}

static int psci_pd_init(struct device_node *np, bool use_osi)
{
        struct generic_pm_domain *pd;
        struct psci_pd_provider *pd_provider;
        struct dev_power_governor *pd_gov;
        int ret = -ENOMEM;

        pd = dt_idle_pd_alloc(np, psci_dt_parse_state_node);
        if (!pd)
                goto out;

        pd_provider = kzalloc_obj(*pd_provider);
        if (!pd_provider)
                goto free_pd;

        pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;

        /*
         * Allow power off when OSI has been successfully enabled.
         * On a PREEMPT_RT based configuration the domain idle states are
         * supported, but only during system-wide suspend.
         */
        if (use_osi) {
                pd->power_off = psci_pd_power_off;
                pd->flags |= GENPD_FLAG_ACTIVE_WAKEUP;
                if (IS_ENABLED(CONFIG_PREEMPT_RT))
                        pd->flags |= GENPD_FLAG_RPM_ALWAYS_ON;
        } else {
                pd->flags |= GENPD_FLAG_ALWAYS_ON;
        }

        /* Use governor for CPU PM domains if it has some states to manage. */
        pd_gov = pd->states ? &pm_domain_cpu_gov : NULL;

        ret = pm_genpd_init(pd, pd_gov, false);
        if (ret)
                goto free_pd_prov;

        ret = of_genpd_add_provider_simple(np, pd);
        if (ret)
                goto remove_pd;

        pd_provider->node = of_node_get(np);
        list_add(&pd_provider->link, &psci_pd_providers);

        pr_debug("init PM domain %s\n", pd->name);
        return 0;

remove_pd:
        pm_genpd_remove(pd);
free_pd_prov:
        kfree(pd_provider);
free_pd:
        dt_idle_pd_free(pd);
out:
        pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
        return ret;
}

static void psci_pd_remove(void)
{
        struct psci_pd_provider *pd_provider, *it;
        struct generic_pm_domain *genpd;

        list_for_each_entry_safe_reverse(pd_provider, it,
                                         &psci_pd_providers, link) {
                of_genpd_del_provider(pd_provider->node);

                genpd = of_genpd_remove_last(pd_provider->node);
                if (!IS_ERR(genpd))
                        kfree(genpd);

                of_node_put(pd_provider->node);
                list_del(&pd_provider->link);
                kfree(pd_provider);
        }
}

static const struct of_device_id psci_of_match[] = {
        { .compatible = "arm,psci-1.0" },
        {}
};

static int psci_cpuidle_domain_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        bool use_osi = psci_has_osi_support();
        int ret = 0, pd_count = 0;

        if (!np)
                return -ENODEV;

        /*
         * Parse child nodes for the "#power-domain-cells" property and
         * initialize a genpd/genpd-of-provider pair when it's found.
         */
        for_each_child_of_node_scoped(np, node) {
                if (!of_property_present(node, "#power-domain-cells"))
                        continue;

                ret = psci_pd_init(node, use_osi);
                if (ret)
                        goto exit;

                pd_count++;
        }

        /* Bail out if not using the hierarchical CPU topology. */
        if (!pd_count)
                return 0;

        /* Link genpd masters/subdomains to model the CPU topology. */
        ret = dt_idle_pd_init_topology(np);
        if (ret)
                goto remove_pd;

        /* let's try to enable OSI. */
        ret = psci_set_osi_mode(use_osi);
        if (ret)
                goto remove_pd;

        pr_info("Initialized CPU PM domain topology using %s mode\n",
                use_osi ? "OSI" : "PC");
        return 0;

remove_pd:
        dt_idle_pd_remove_topology(np);
        psci_pd_remove();
exit:
        pr_err("failed to create CPU PM domains ret=%d\n", ret);
        return ret;
}

static struct platform_driver psci_cpuidle_domain_driver = {
        .probe  = psci_cpuidle_domain_probe,
        .driver = {
                .name = "psci-cpuidle-domain",
                .of_match_table = psci_of_match,
        },
};

static int __init psci_idle_init_domains(void)
{
        return platform_driver_register(&psci_cpuidle_domain_driver);
}
core_initcall(psci_idle_init_domains);