// 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"

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

static LIST_HEAD(psci_pd_providers);
static bool psci_pd_allow_domain_state;

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;

        if (!psci_pd_allow_domain_state)
                return -EBUSY;

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

        return 0;
}

static int psci_pd_parse_state_nodes(struct genpd_power_state *states,
                                     int state_count)
{
        int i, ret;
        u32 psci_state, *psci_state_buf;

        for (i = 0; i < state_count; i++) {
                ret = psci_dt_parse_state_node(to_of_node(states[i].fwnode),
                                        &psci_state);
                if (ret)
                        goto free_state;

                psci_state_buf = kmalloc(sizeof(u32), GFP_KERNEL);
                if (!psci_state_buf) {
                        ret = -ENOMEM;
                        goto free_state;
                }
                *psci_state_buf = psci_state;
                states[i].data = psci_state_buf;
        }

        return 0;

free_state:
        i--;
        for (; i >= 0; i--)
                kfree(states[i].data);
        return ret;
}

static int psci_pd_parse_states(struct device_node *np,
                        struct genpd_power_state **states, int *state_count)
{
        int ret;

        /* Parse the domain idle states. */
        ret = of_genpd_parse_idle_states(np, states, state_count);
        if (ret)
                return ret;

        /* Fill out the PSCI specifics for each found state. */
        ret = psci_pd_parse_state_nodes(*states, *state_count);
        if (ret)
                kfree(*states);

        return ret;
}

static void psci_pd_free_states(struct genpd_power_state *states,
                                unsigned int state_count)
{
        int i;

        for (i = 0; i < state_count; i++)
                kfree(states[i].data);
        kfree(states);
}

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;
        struct genpd_power_state *states = NULL;
        int ret = -ENOMEM, state_count = 0;

        pd = kzalloc(sizeof(*pd), GFP_KERNEL);
        if (!pd)
                goto out;

        pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
        if (!pd_provider)
                goto free_pd;

        pd->name = kasprintf(GFP_KERNEL, "%pOF", np);
        if (!pd->name)
                goto free_pd_prov;

        /*
         * Parse the domain idle states and let genpd manage the state selection
         * for those being compatible with "domain-idle-state".
         */
        ret = psci_pd_parse_states(np, &states, &state_count);
        if (ret)
                goto free_name;

        pd->free_states = psci_pd_free_states;
        pd->name = kbasename(pd->name);
        pd->states = states;
        pd->state_count = state_count;
        pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;

        /* Allow power off when OSI has been successfully enabled. */
        if (use_osi)
                pd->power_off = psci_pd_power_off;
        else
                pd->flags |= GENPD_FLAG_ALWAYS_ON;

        /* Use governor for CPU PM domains if it has some states to manage. */
        pd_gov = state_count > 0 ? &pm_domain_cpu_gov : NULL;

        ret = pm_genpd_init(pd, pd_gov, false);
        if (ret) {
                psci_pd_free_states(states, state_count);
                goto free_name;
        }

        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_name:
        kfree(pd->name);
free_pd_prov:
        kfree(pd_provider);
free_pd:
        kfree(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(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 int psci_pd_init_topology(struct device_node *np)
{
        struct device_node *node;
        struct of_phandle_args child, parent;
        int ret;

        for_each_child_of_node(np, node) {
                if (of_parse_phandle_with_args(node, "power-domains",
                                        "#power-domain-cells", 0, &parent))
                        continue;

                child.np = node;
                child.args_count = 0;
                ret = of_genpd_add_subdomain(&parent, &child);
                of_node_put(parent.np);
                if (ret) {
                        of_node_put(node);
                        return ret;
                }
        }

        return 0;
}

static bool psci_pd_try_set_osi_mode(void)
{
        int ret;

        if (!psci_has_osi_support())
                return false;

        ret = psci_set_osi_mode(true);
        if (ret) {
                pr_warn("failed to enable OSI mode: %d\n", ret);
                return false;
        }

        return true;
}

static void psci_cpuidle_domain_sync_state(struct device *dev)
{
        /*
         * All devices have now been attached/probed to the PM domain topology,
         * hence it's fine to allow domain states to be picked.
         */
        psci_pd_allow_domain_state = true;
}

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;
        struct device_node *node;
        bool use_osi;
        int ret = 0, pd_count = 0;

        if (!np)
                return -ENODEV;

        /* If OSI mode is supported, let's try to enable it. */
        use_osi = psci_pd_try_set_osi_mode();

        /*
         * 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(np, node) {
                if (!of_find_property(node, "#power-domain-cells", NULL))
                        continue;

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

                pd_count++;
        }

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

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

        pr_info("Initialized CPU PM domain topology\n");
        return 0;

put_node:
        of_node_put(node);
remove_pd:
        psci_pd_remove();
        pr_err("failed to create CPU PM domains ret=%d\n", ret);
no_pd:
        if (use_osi)
                psci_set_osi_mode(false);
        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,
                .sync_state = psci_cpuidle_domain_sync_state,
        },
};

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

struct device *psci_dt_attach_cpu(int cpu)
{
        struct device *dev;

        dev = dev_pm_domain_attach_by_name(get_cpu_device(cpu), "psci");
        if (IS_ERR_OR_NULL(dev))
                return dev;

        pm_runtime_irq_safe(dev);
        if (cpu_online(cpu))
                pm_runtime_get_sync(dev);

        dev_pm_syscore_device(dev, true);

        return dev;
}

void psci_dt_detach_cpu(struct device *dev)
{
        if (IS_ERR_OR_NULL(dev))
                return;

        dev_pm_domain_detach(dev, false);
}