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 
24 struct psci_pd_provider {
25 	struct list_head link;
26 	struct device_node *node;
27 };
28 
29 static LIST_HEAD(psci_pd_providers);
30 static bool psci_pd_allow_domain_state;
31 
32 static 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 
50 static 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 
93 remove_pd:
94 	pm_genpd_remove(pd);
95 free_pd_prov:
96 	kfree(pd_provider);
97 free_pd:
98 	dt_idle_pd_free(pd);
99 out:
100 	pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
101 	return ret;
102 }
103 
104 static 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 
123 static 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 
132 static const struct of_device_id psci_of_match[] = {
133 	{ .compatible = "arm,psci-1.0" },
134 	{}
135 };
136 
137 static 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 
182 remove_pd:
183 	dt_idle_pd_remove_topology(np);
184 	psci_pd_remove();
185 exit:
186 	pr_err("failed to create CPU PM domains ret=%d\n", ret);
187 	return ret;
188 }
189 
190 static 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 
199 static int __init psci_idle_init_domains(void)
200 {
201 	return platform_driver_register(&psci_cpuidle_domain_driver);
202 }
203 subsys_initcall(psci_idle_init_domains);
204