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_parse_state_nodes(struct genpd_power_state *states,
51 				     int state_count)
52 {
53 	int i, ret;
54 	u32 psci_state, *psci_state_buf;
55 
56 	for (i = 0; i < state_count; i++) {
57 		ret = psci_dt_parse_state_node(to_of_node(states[i].fwnode),
58 					&psci_state);
59 		if (ret)
60 			goto free_state;
61 
62 		psci_state_buf = kmalloc(sizeof(u32), GFP_KERNEL);
63 		if (!psci_state_buf) {
64 			ret = -ENOMEM;
65 			goto free_state;
66 		}
67 		*psci_state_buf = psci_state;
68 		states[i].data = psci_state_buf;
69 	}
70 
71 	return 0;
72 
73 free_state:
74 	i--;
75 	for (; i >= 0; i--)
76 		kfree(states[i].data);
77 	return ret;
78 }
79 
80 static int psci_pd_parse_states(struct device_node *np,
81 			struct genpd_power_state **states, int *state_count)
82 {
83 	int ret;
84 
85 	/* Parse the domain idle states. */
86 	ret = of_genpd_parse_idle_states(np, states, state_count);
87 	if (ret)
88 		return ret;
89 
90 	/* Fill out the PSCI specifics for each found state. */
91 	ret = psci_pd_parse_state_nodes(*states, *state_count);
92 	if (ret)
93 		kfree(*states);
94 
95 	return ret;
96 }
97 
98 static void psci_pd_free_states(struct genpd_power_state *states,
99 				unsigned int state_count)
100 {
101 	int i;
102 
103 	for (i = 0; i < state_count; i++)
104 		kfree(states[i].data);
105 	kfree(states);
106 }
107 
108 static int psci_pd_init(struct device_node *np, bool use_osi)
109 {
110 	struct generic_pm_domain *pd;
111 	struct psci_pd_provider *pd_provider;
112 	struct dev_power_governor *pd_gov;
113 	struct genpd_power_state *states = NULL;
114 	int ret = -ENOMEM, state_count = 0;
115 
116 	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
117 	if (!pd)
118 		goto out;
119 
120 	pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
121 	if (!pd_provider)
122 		goto free_pd;
123 
124 	pd->name = kasprintf(GFP_KERNEL, "%pOF", np);
125 	if (!pd->name)
126 		goto free_pd_prov;
127 
128 	/*
129 	 * Parse the domain idle states and let genpd manage the state selection
130 	 * for those being compatible with "domain-idle-state".
131 	 */
132 	ret = psci_pd_parse_states(np, &states, &state_count);
133 	if (ret)
134 		goto free_name;
135 
136 	pd->free_states = psci_pd_free_states;
137 	pd->name = kbasename(pd->name);
138 	pd->states = states;
139 	pd->state_count = state_count;
140 	pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
141 
142 	/* Allow power off when OSI has been successfully enabled. */
143 	if (use_osi)
144 		pd->power_off = psci_pd_power_off;
145 	else
146 		pd->flags |= GENPD_FLAG_ALWAYS_ON;
147 
148 	/* Use governor for CPU PM domains if it has some states to manage. */
149 	pd_gov = state_count > 0 ? &pm_domain_cpu_gov : NULL;
150 
151 	ret = pm_genpd_init(pd, pd_gov, false);
152 	if (ret) {
153 		psci_pd_free_states(states, state_count);
154 		goto free_name;
155 	}
156 
157 	ret = of_genpd_add_provider_simple(np, pd);
158 	if (ret)
159 		goto remove_pd;
160 
161 	pd_provider->node = of_node_get(np);
162 	list_add(&pd_provider->link, &psci_pd_providers);
163 
164 	pr_debug("init PM domain %s\n", pd->name);
165 	return 0;
166 
167 remove_pd:
168 	pm_genpd_remove(pd);
169 free_name:
170 	kfree(pd->name);
171 free_pd_prov:
172 	kfree(pd_provider);
173 free_pd:
174 	kfree(pd);
175 out:
176 	pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
177 	return ret;
178 }
179 
180 static void psci_pd_remove(void)
181 {
182 	struct psci_pd_provider *pd_provider, *it;
183 	struct generic_pm_domain *genpd;
184 
185 	list_for_each_entry_safe(pd_provider, it, &psci_pd_providers, link) {
186 		of_genpd_del_provider(pd_provider->node);
187 
188 		genpd = of_genpd_remove_last(pd_provider->node);
189 		if (!IS_ERR(genpd))
190 			kfree(genpd);
191 
192 		of_node_put(pd_provider->node);
193 		list_del(&pd_provider->link);
194 		kfree(pd_provider);
195 	}
196 }
197 
198 static int psci_pd_init_topology(struct device_node *np)
199 {
200 	struct device_node *node;
201 	struct of_phandle_args child, parent;
202 	int ret;
203 
204 	for_each_child_of_node(np, node) {
205 		if (of_parse_phandle_with_args(node, "power-domains",
206 					"#power-domain-cells", 0, &parent))
207 			continue;
208 
209 		child.np = node;
210 		child.args_count = 0;
211 		ret = of_genpd_add_subdomain(&parent, &child);
212 		of_node_put(parent.np);
213 		if (ret) {
214 			of_node_put(node);
215 			return ret;
216 		}
217 	}
218 
219 	return 0;
220 }
221 
222 static bool psci_pd_try_set_osi_mode(void)
223 {
224 	int ret;
225 
226 	if (!psci_has_osi_support())
227 		return false;
228 
229 	ret = psci_set_osi_mode(true);
230 	if (ret) {
231 		pr_warn("failed to enable OSI mode: %d\n", ret);
232 		return false;
233 	}
234 
235 	return true;
236 }
237 
238 static void psci_cpuidle_domain_sync_state(struct device *dev)
239 {
240 	/*
241 	 * All devices have now been attached/probed to the PM domain topology,
242 	 * hence it's fine to allow domain states to be picked.
243 	 */
244 	psci_pd_allow_domain_state = true;
245 }
246 
247 static const struct of_device_id psci_of_match[] = {
248 	{ .compatible = "arm,psci-1.0" },
249 	{}
250 };
251 
252 static int psci_cpuidle_domain_probe(struct platform_device *pdev)
253 {
254 	struct device_node *np = pdev->dev.of_node;
255 	struct device_node *node;
256 	bool use_osi;
257 	int ret = 0, pd_count = 0;
258 
259 	if (!np)
260 		return -ENODEV;
261 
262 	/* If OSI mode is supported, let's try to enable it. */
263 	use_osi = psci_pd_try_set_osi_mode();
264 
265 	/*
266 	 * Parse child nodes for the "#power-domain-cells" property and
267 	 * initialize a genpd/genpd-of-provider pair when it's found.
268 	 */
269 	for_each_child_of_node(np, node) {
270 		if (!of_find_property(node, "#power-domain-cells", NULL))
271 			continue;
272 
273 		ret = psci_pd_init(node, use_osi);
274 		if (ret)
275 			goto put_node;
276 
277 		pd_count++;
278 	}
279 
280 	/* Bail out if not using the hierarchical CPU topology. */
281 	if (!pd_count)
282 		goto no_pd;
283 
284 	/* Link genpd masters/subdomains to model the CPU topology. */
285 	ret = psci_pd_init_topology(np);
286 	if (ret)
287 		goto remove_pd;
288 
289 	pr_info("Initialized CPU PM domain topology\n");
290 	return 0;
291 
292 put_node:
293 	of_node_put(node);
294 remove_pd:
295 	psci_pd_remove();
296 	pr_err("failed to create CPU PM domains ret=%d\n", ret);
297 no_pd:
298 	if (use_osi)
299 		psci_set_osi_mode(false);
300 	return ret;
301 }
302 
303 static struct platform_driver psci_cpuidle_domain_driver = {
304 	.probe  = psci_cpuidle_domain_probe,
305 	.driver = {
306 		.name = "psci-cpuidle-domain",
307 		.of_match_table = psci_of_match,
308 		.sync_state = psci_cpuidle_domain_sync_state,
309 	},
310 };
311 
312 static int __init psci_idle_init_domains(void)
313 {
314 	return platform_driver_register(&psci_cpuidle_domain_driver);
315 }
316 subsys_initcall(psci_idle_init_domains);
317 
318 struct device *psci_dt_attach_cpu(int cpu)
319 {
320 	struct device *dev;
321 
322 	dev = dev_pm_domain_attach_by_name(get_cpu_device(cpu), "psci");
323 	if (IS_ERR_OR_NULL(dev))
324 		return dev;
325 
326 	pm_runtime_irq_safe(dev);
327 	if (cpu_online(cpu))
328 		pm_runtime_get_sync(dev);
329 
330 	return dev;
331 }
332 
333 void psci_dt_detach_cpu(struct device *dev)
334 {
335 	if (IS_ERR_OR_NULL(dev))
336 		return;
337 
338 	dev_pm_domain_detach(dev, false);
339 }
340