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#include "dt_idle_genpd.h"
 24
 25struct psci_pd_provider {
 26	struct list_head link;
 27	struct device_node *node;
 28};
 29
 30static LIST_HEAD(psci_pd_providers);
 31static bool psci_pd_allow_domain_state;
 32
 33static int psci_pd_power_off(struct generic_pm_domain *pd)
 34{
 35	struct genpd_power_state *state = &pd->states[pd->state_idx];
 36	u32 *pd_state;
 37
 38	if (!state->data)
 39		return 0;
 40
 41	if (!psci_pd_allow_domain_state)
 42		return -EBUSY;
 43
 44	/* OSI mode is enabled, set the corresponding domain state. */
 45	pd_state = state->data;
 46	psci_set_domain_state(*pd_state);
 47
 48	return 0;
 49}
 50
 51static int psci_pd_init(struct device_node *np, bool use_osi)
 52{
 53	struct generic_pm_domain *pd;
 54	struct psci_pd_provider *pd_provider;
 55	struct dev_power_governor *pd_gov;
 56	int ret = -ENOMEM;
 57
 58	pd = dt_idle_pd_alloc(np, psci_dt_parse_state_node);
 59	if (!pd)
 60		goto out;
 61
 62	pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
 63	if (!pd_provider)
 64		goto free_pd;
 65
 66	pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
 67
 68	/*
 69	 * Allow power off when OSI has been successfully enabled.
 70	 * On a PREEMPT_RT based configuration the domain idle states are
 71	 * supported, but only during system-wide suspend.
 72	 */
 73	if (use_osi) {
 74		pd->power_off = psci_pd_power_off;
 75		if (IS_ENABLED(CONFIG_PREEMPT_RT))
 76			pd->flags |= GENPD_FLAG_RPM_ALWAYS_ON;
 77	} else {
 78		pd->flags |= GENPD_FLAG_ALWAYS_ON;
 79	}
 80
 81	/* Use governor for CPU PM domains if it has some states to manage. */
 82	pd_gov = pd->states ? &pm_domain_cpu_gov : NULL;
 83
 84	ret = pm_genpd_init(pd, pd_gov, false);
 85	if (ret)
 86		goto free_pd_prov;
 87
 88	ret = of_genpd_add_provider_simple(np, pd);
 89	if (ret)
 90		goto remove_pd;
 91
 92	pd_provider->node = of_node_get(np);
 93	list_add(&pd_provider->link, &psci_pd_providers);
 94
 95	pr_debug("init PM domain %s\n", pd->name);
 96	return 0;
 97
 98remove_pd:
 99	pm_genpd_remove(pd);
100free_pd_prov:
101	kfree(pd_provider);
102free_pd:
103	dt_idle_pd_free(pd);
104out:
105	pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
106	return ret;
107}
108
109static void psci_pd_remove(void)
110{
111	struct psci_pd_provider *pd_provider, *it;
112	struct generic_pm_domain *genpd;
113
114	list_for_each_entry_safe_reverse(pd_provider, it,
115					 &psci_pd_providers, link) {
116		of_genpd_del_provider(pd_provider->node);
117
118		genpd = of_genpd_remove_last(pd_provider->node);
119		if (!IS_ERR(genpd))
120			kfree(genpd);
121
122		of_node_put(pd_provider->node);
123		list_del(&pd_provider->link);
124		kfree(pd_provider);
125	}
126}
127
128static void psci_cpuidle_domain_sync_state(struct device *dev)
129{
130	/*
131	 * All devices have now been attached/probed to the PM domain topology,
132	 * hence it's fine to allow domain states to be picked.
133	 */
134	psci_pd_allow_domain_state = true;
135}
136
137static const struct of_device_id psci_of_match[] = {
138	{ .compatible = "arm,psci-1.0" },
139	{}
140};
141
142static int psci_cpuidle_domain_probe(struct platform_device *pdev)
143{
144	struct device_node *np = pdev->dev.of_node;
145	bool use_osi = psci_has_osi_support();
146	int ret = 0, pd_count = 0;
147
148	if (!np)
149		return -ENODEV;
150
151	/*
152	 * Parse child nodes for the "#power-domain-cells" property and
153	 * initialize a genpd/genpd-of-provider pair when it's found.
154	 */
155	for_each_child_of_node_scoped(np, node) {
156		if (!of_property_present(node, "#power-domain-cells"))
157			continue;
158
159		ret = psci_pd_init(node, use_osi);
160		if (ret)
161			goto exit;
162
163		pd_count++;
164	}
165
166	/* Bail out if not using the hierarchical CPU topology. */
167	if (!pd_count)
168		return 0;
169
170	/* Link genpd masters/subdomains to model the CPU topology. */
171	ret = dt_idle_pd_init_topology(np);
172	if (ret)
173		goto remove_pd;
174
175	/* let's try to enable OSI. */
176	ret = psci_set_osi_mode(use_osi);
177	if (ret)
178		goto remove_pd;
179
180	pr_info("Initialized CPU PM domain topology using %s mode\n",
181		use_osi ? "OSI" : "PC");
182	return 0;
183
184remove_pd:
185	dt_idle_pd_remove_topology(np);
186	psci_pd_remove();
187exit:
188	pr_err("failed to create CPU PM domains ret=%d\n", ret);
189	return ret;
190}
191
192static struct platform_driver psci_cpuidle_domain_driver = {
193	.probe  = psci_cpuidle_domain_probe,
194	.driver = {
195		.name = "psci-cpuidle-domain",
196		.of_match_table = psci_of_match,
197		.sync_state = psci_cpuidle_domain_sync_state,
198	},
199};
200
201static int __init psci_idle_init_domains(void)
202{
203	return platform_driver_register(&psci_cpuidle_domain_driver);
204}
205core_initcall(psci_idle_init_domains);