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, state_count = 0;
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 	/* Allow power off when OSI has been successfully enabled. */
68 	if (use_osi)
69 		pd->power_off = psci_pd_power_off;
70 	else
71 		pd->flags |= GENPD_FLAG_ALWAYS_ON;
72 
73 	/* Use governor for CPU PM domains if it has some states to manage. */
74 	pd_gov = state_count > 0 ? &pm_domain_cpu_gov : NULL;
75 
76 	ret = pm_genpd_init(pd, pd_gov, false);
77 	if (ret)
78 		goto free_pd_prov;
79 
80 	ret = of_genpd_add_provider_simple(np, pd);
81 	if (ret)
82 		goto remove_pd;
83 
84 	pd_provider->node = of_node_get(np);
85 	list_add(&pd_provider->link, &psci_pd_providers);
86 
87 	pr_debug("init PM domain %s\n", pd->name);
88 	return 0;
89 
90 remove_pd:
91 	pm_genpd_remove(pd);
92 free_pd_prov:
93 	kfree(pd_provider);
94 free_pd:
95 	dt_idle_pd_free(pd);
96 out:
97 	pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
98 	return ret;
99 }
100 
101 static void psci_pd_remove(void)
102 {
103 	struct psci_pd_provider *pd_provider, *it;
104 	struct generic_pm_domain *genpd;
105 
106 	list_for_each_entry_safe(pd_provider, it, &psci_pd_providers, link) {
107 		of_genpd_del_provider(pd_provider->node);
108 
109 		genpd = of_genpd_remove_last(pd_provider->node);
110 		if (!IS_ERR(genpd))
111 			kfree(genpd);
112 
113 		of_node_put(pd_provider->node);
114 		list_del(&pd_provider->link);
115 		kfree(pd_provider);
116 	}
117 }
118 
119 static bool psci_pd_try_set_osi_mode(void)
120 {
121 	int ret;
122 
123 	if (!psci_has_osi_support())
124 		return false;
125 
126 	ret = psci_set_osi_mode(true);
127 	if (ret) {
128 		pr_warn("failed to enable OSI mode: %d\n", ret);
129 		return false;
130 	}
131 
132 	return true;
133 }
134 
135 static void psci_cpuidle_domain_sync_state(struct device *dev)
136 {
137 	/*
138 	 * All devices have now been attached/probed to the PM domain topology,
139 	 * hence it's fine to allow domain states to be picked.
140 	 */
141 	psci_pd_allow_domain_state = true;
142 }
143 
144 static const struct of_device_id psci_of_match[] = {
145 	{ .compatible = "arm,psci-1.0" },
146 	{}
147 };
148 
149 static int psci_cpuidle_domain_probe(struct platform_device *pdev)
150 {
151 	struct device_node *np = pdev->dev.of_node;
152 	struct device_node *node;
153 	bool use_osi;
154 	int ret = 0, pd_count = 0;
155 
156 	if (!np)
157 		return -ENODEV;
158 
159 	/* If OSI mode is supported, let's try to enable it. */
160 	use_osi = psci_pd_try_set_osi_mode();
161 
162 	/*
163 	 * Parse child nodes for the "#power-domain-cells" property and
164 	 * initialize a genpd/genpd-of-provider pair when it's found.
165 	 */
166 	for_each_child_of_node(np, node) {
167 		if (!of_find_property(node, "#power-domain-cells", NULL))
168 			continue;
169 
170 		ret = psci_pd_init(node, use_osi);
171 		if (ret)
172 			goto put_node;
173 
174 		pd_count++;
175 	}
176 
177 	/* Bail out if not using the hierarchical CPU topology. */
178 	if (!pd_count)
179 		goto no_pd;
180 
181 	/* Link genpd masters/subdomains to model the CPU topology. */
182 	ret = dt_idle_pd_init_topology(np);
183 	if (ret)
184 		goto remove_pd;
185 
186 	pr_info("Initialized CPU PM domain topology\n");
187 	return 0;
188 
189 put_node:
190 	of_node_put(node);
191 remove_pd:
192 	psci_pd_remove();
193 	pr_err("failed to create CPU PM domains ret=%d\n", ret);
194 no_pd:
195 	if (use_osi)
196 		psci_set_osi_mode(false);
197 	return ret;
198 }
199 
200 static struct platform_driver psci_cpuidle_domain_driver = {
201 	.probe  = psci_cpuidle_domain_probe,
202 	.driver = {
203 		.name = "psci-cpuidle-domain",
204 		.of_match_table = psci_of_match,
205 		.sync_state = psci_cpuidle_domain_sync_state,
206 	},
207 };
208 
209 static int __init psci_idle_init_domains(void)
210 {
211 	return platform_driver_register(&psci_cpuidle_domain_driver);
212 }
213 subsys_initcall(psci_idle_init_domains);
214