// 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
  ", 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
  ", 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
  ", 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
  ");

  	return 0;

  
  put_node:
  	of_node_put(node);
  remove_pd:

  	psci_pd_remove();

  	pr_err("failed to create CPU PM domains ret=%d
  ", 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);
  }