1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * PM domains for CPUs via genpd - managed by cpuidle-psci.
  4 *
  5 * Copyright (C) 2019 Linaro Ltd.
  6 * Author: Ulf Hansson <ulf.hansson@linaro.org>
  7 *
  8 */
  9
 10#define pr_fmt(fmt) "CPUidle PSCI: " fmt
 11
 12#include <linux/cpu.h>
 13#include <linux/device.h>
 14#include <linux/kernel.h>
 15#include <linux/platform_device.h>
 16#include <linux/pm_domain.h>
 17#include <linux/pm_runtime.h>
 18#include <linux/psci.h>
 19#include <linux/slab.h>
 20#include <linux/string.h>
 21
 22#include "cpuidle-psci.h"
 23
 24struct psci_pd_provider {
 25	struct list_head link;
 26	struct device_node *node;
 27};
 28
 29static LIST_HEAD(psci_pd_providers);
 30static bool psci_pd_allow_domain_state;
 31
 32static int psci_pd_power_off(struct generic_pm_domain *pd)
 33{
 34	struct genpd_power_state *state = &pd->states[pd->state_idx];
 35	u32 *pd_state;
 36
 37	if (!state->data)
 38		return 0;
 39
 40	if (!psci_pd_allow_domain_state)
 41		return -EBUSY;
 42
 43	/* OSI mode is enabled, set the corresponding domain state. */
 44	pd_state = state->data;
 45	psci_set_domain_state(*pd_state);
 46
 47	return 0;
 48}
 49
 50static int psci_pd_init(struct device_node *np, bool use_osi)
 51{
 52	struct generic_pm_domain *pd;
 53	struct psci_pd_provider *pd_provider;
 54	struct dev_power_governor *pd_gov;
 55	int ret = -ENOMEM;
 56
 57	pd = dt_idle_pd_alloc(np, psci_dt_parse_state_node);
 58	if (!pd)
 59		goto out;
 60
 61	pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
 62	if (!pd_provider)
 63		goto free_pd;
 64
 65	pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
 66
 67	/*
 68	 * Allow power off when OSI has been successfully enabled.
 69	 * PREEMPT_RT is not yet ready to enter domain idle states.
 70	 */
 71	if (use_osi && !IS_ENABLED(CONFIG_PREEMPT_RT))
 72		pd->power_off = psci_pd_power_off;
 73	else
 74		pd->flags |= GENPD_FLAG_ALWAYS_ON;
 75
 76	/* Use governor for CPU PM domains if it has some states to manage. */
 77	pd_gov = pd->states ? &pm_domain_cpu_gov : NULL;
 78
 79	ret = pm_genpd_init(pd, pd_gov, false);
 80	if (ret)
 81		goto free_pd_prov;
 82
 83	ret = of_genpd_add_provider_simple(np, pd);
 84	if (ret)
 85		goto remove_pd;
 86
 87	pd_provider->node = of_node_get(np);
 88	list_add(&pd_provider->link, &psci_pd_providers);
 89
 90	pr_debug("init PM domain %s\n", pd->name);
 91	return 0;
 92
 93remove_pd:
 94	pm_genpd_remove(pd);
 95free_pd_prov:
 96	kfree(pd_provider);
 97free_pd:
 98	dt_idle_pd_free(pd);
 99out:
100	pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
101	return ret;
102}
103
104static void psci_pd_remove(void)
105{
106	struct psci_pd_provider *pd_provider, *it;
107	struct generic_pm_domain *genpd;
108
109	list_for_each_entry_safe_reverse(pd_provider, it,
110					 &psci_pd_providers, link) {
111		of_genpd_del_provider(pd_provider->node);
112
113		genpd = of_genpd_remove_last(pd_provider->node);
114		if (!IS_ERR(genpd))
115			kfree(genpd);
116
117		of_node_put(pd_provider->node);
118		list_del(&pd_provider->link);
119		kfree(pd_provider);
120	}
121}
122
123static void psci_cpuidle_domain_sync_state(struct device *dev)
124{
125	/*
126	 * All devices have now been attached/probed to the PM domain topology,
127	 * hence it's fine to allow domain states to be picked.
128	 */
129	psci_pd_allow_domain_state = true;
130}
131
132static const struct of_device_id psci_of_match[] = {
133	{ .compatible = "arm,psci-1.0" },
134	{}
135};
136
137static int psci_cpuidle_domain_probe(struct platform_device *pdev)
138{
139	struct device_node *np = pdev->dev.of_node;
140	struct device_node *node;
141	bool use_osi = psci_has_osi_support();
142	int ret = 0, pd_count = 0;
143
144	if (!np)
145		return -ENODEV;
146
147	/*
148	 * Parse child nodes for the "#power-domain-cells" property and
149	 * initialize a genpd/genpd-of-provider pair when it's found.
150	 */
151	for_each_child_of_node(np, node) {
152		if (!of_property_present(node, "#power-domain-cells"))
153			continue;
154
155		ret = psci_pd_init(node, use_osi);
156		if (ret) {
157			of_node_put(node);
158			goto exit;
159		}
160
161		pd_count++;
162	}
163
164	/* Bail out if not using the hierarchical CPU topology. */
165	if (!pd_count)
166		return 0;
167
168	/* Link genpd masters/subdomains to model the CPU topology. */
169	ret = dt_idle_pd_init_topology(np);
170	if (ret)
171		goto remove_pd;
172
173	/* let's try to enable OSI. */
174	ret = psci_set_osi_mode(use_osi);
175	if (ret)
176		goto remove_pd;
177
178	pr_info("Initialized CPU PM domain topology using %s mode\n",
179		use_osi ? "OSI" : "PC");
180	return 0;
181
182remove_pd:
183	dt_idle_pd_remove_topology(np);
184	psci_pd_remove();
185exit:
186	pr_err("failed to create CPU PM domains ret=%d\n", ret);
187	return ret;
188}
189
190static struct platform_driver psci_cpuidle_domain_driver = {
191	.probe  = psci_cpuidle_domain_probe,
192	.driver = {
193		.name = "psci-cpuidle-domain",
194		.of_match_table = psci_of_match,
195		.sync_state = psci_cpuidle_domain_sync_state,
196	},
197};
198
199static int __init psci_idle_init_domains(void)
200{
201	return platform_driver_register(&psci_cpuidle_domain_driver);
202}
203subsys_initcall(psci_idle_init_domains);