1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * PSCI CPU idle driver.
4  *
5  * Copyright (C) 2019 ARM Ltd.
6  * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
7  */
8 
9 #define pr_fmt(fmt) "CPUidle PSCI: " fmt
10 
11 #include <linux/cpuhotplug.h>
12 #include <linux/cpu_cooling.h>
13 #include <linux/cpuidle.h>
14 #include <linux/cpumask.h>
15 #include <linux/cpu_pm.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/of.h>
19 #include <linux/platform_device.h>
20 #include <linux/psci.h>
21 #include <linux/pm_domain.h>
22 #include <linux/pm_runtime.h>
23 #include <linux/slab.h>
24 #include <linux/string.h>
25 #include <linux/syscore_ops.h>
26 
27 #include <asm/cpuidle.h>
28 
29 #include "cpuidle-psci.h"
30 #include "dt_idle_states.h"
31 
32 struct psci_cpuidle_data {
33 	u32 *psci_states;
34 	struct device *dev;
35 };
36 
37 static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
38 static DEFINE_PER_CPU(u32, domain_state);
39 static bool psci_cpuidle_use_cpuhp;
40 
psci_set_domain_state(u32 state)41 void psci_set_domain_state(u32 state)
42 {
43 	__this_cpu_write(domain_state, state);
44 }
45 
psci_get_domain_state(void)46 static inline u32 psci_get_domain_state(void)
47 {
48 	return __this_cpu_read(domain_state);
49 }
50 
__psci_enter_domain_idle_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx,bool s2idle)51 static __cpuidle int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
52 						    struct cpuidle_driver *drv, int idx,
53 						    bool s2idle)
54 {
55 	struct psci_cpuidle_data *data = this_cpu_ptr(&psci_cpuidle_data);
56 	u32 *states = data->psci_states;
57 	struct device *pd_dev = data->dev;
58 	u32 state;
59 	int ret;
60 
61 	ret = cpu_pm_enter();
62 	if (ret)
63 		return -1;
64 
65 	/* Do runtime PM to manage a hierarchical CPU toplogy. */
66 	if (s2idle)
67 		dev_pm_genpd_suspend(pd_dev);
68 	else
69 		pm_runtime_put_sync_suspend(pd_dev);
70 
71 	state = psci_get_domain_state();
72 	if (!state)
73 		state = states[idx];
74 
75 	ret = psci_cpu_suspend_enter(state) ? -1 : idx;
76 
77 	if (s2idle)
78 		dev_pm_genpd_resume(pd_dev);
79 	else
80 		pm_runtime_get_sync(pd_dev);
81 
82 	cpu_pm_exit();
83 
84 	/* Clear the domain state to start fresh when back from idle. */
85 	psci_set_domain_state(0);
86 	return ret;
87 }
88 
psci_enter_domain_idle_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx)89 static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
90 					struct cpuidle_driver *drv, int idx)
91 {
92 	return __psci_enter_domain_idle_state(dev, drv, idx, false);
93 }
94 
psci_enter_s2idle_domain_idle_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx)95 static int psci_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
96 					       struct cpuidle_driver *drv,
97 					       int idx)
98 {
99 	return __psci_enter_domain_idle_state(dev, drv, idx, true);
100 }
101 
psci_idle_cpuhp_up(unsigned int cpu)102 static int psci_idle_cpuhp_up(unsigned int cpu)
103 {
104 	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
105 
106 	if (pd_dev)
107 		pm_runtime_get_sync(pd_dev);
108 
109 	return 0;
110 }
111 
psci_idle_cpuhp_down(unsigned int cpu)112 static int psci_idle_cpuhp_down(unsigned int cpu)
113 {
114 	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
115 
116 	if (pd_dev) {
117 		pm_runtime_put_sync(pd_dev);
118 		/* Clear domain state to start fresh at next online. */
119 		psci_set_domain_state(0);
120 	}
121 
122 	return 0;
123 }
124 
psci_idle_syscore_switch(bool suspend)125 static void psci_idle_syscore_switch(bool suspend)
126 {
127 	bool cleared = false;
128 	struct device *dev;
129 	int cpu;
130 
131 	for_each_possible_cpu(cpu) {
132 		dev = per_cpu_ptr(&psci_cpuidle_data, cpu)->dev;
133 
134 		if (dev && suspend) {
135 			dev_pm_genpd_suspend(dev);
136 		} else if (dev) {
137 			dev_pm_genpd_resume(dev);
138 
139 			/* Account for userspace having offlined a CPU. */
140 			if (pm_runtime_status_suspended(dev))
141 				pm_runtime_set_active(dev);
142 
143 			/* Clear domain state to re-start fresh. */
144 			if (!cleared) {
145 				psci_set_domain_state(0);
146 				cleared = true;
147 			}
148 		}
149 	}
150 }
151 
psci_idle_syscore_suspend(void)152 static int psci_idle_syscore_suspend(void)
153 {
154 	psci_idle_syscore_switch(true);
155 	return 0;
156 }
157 
psci_idle_syscore_resume(void)158 static void psci_idle_syscore_resume(void)
159 {
160 	psci_idle_syscore_switch(false);
161 }
162 
163 static struct syscore_ops psci_idle_syscore_ops = {
164 	.suspend = psci_idle_syscore_suspend,
165 	.resume = psci_idle_syscore_resume,
166 };
167 
psci_idle_init_cpuhp(void)168 static void psci_idle_init_cpuhp(void)
169 {
170 	int err;
171 
172 	if (!psci_cpuidle_use_cpuhp)
173 		return;
174 
175 	register_syscore_ops(&psci_idle_syscore_ops);
176 
177 	err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
178 					"cpuidle/psci:online",
179 					psci_idle_cpuhp_up,
180 					psci_idle_cpuhp_down);
181 	if (err)
182 		pr_warn("Failed %d while setup cpuhp state\n", err);
183 }
184 
psci_enter_idle_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx)185 static __cpuidle int psci_enter_idle_state(struct cpuidle_device *dev,
186 					   struct cpuidle_driver *drv, int idx)
187 {
188 	u32 *state = __this_cpu_read(psci_cpuidle_data.psci_states);
189 
190 	return CPU_PM_CPU_IDLE_ENTER_PARAM_RCU(psci_cpu_suspend_enter, idx, state[idx]);
191 }
192 
193 static const struct of_device_id psci_idle_state_match[] = {
194 	{ .compatible = "arm,idle-state",
195 	  .data = psci_enter_idle_state },
196 	{ },
197 };
198 
psci_dt_parse_state_node(struct device_node * np,u32 * state)199 int psci_dt_parse_state_node(struct device_node *np, u32 *state)
200 {
201 	int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
202 
203 	if (err) {
204 		pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
205 		return err;
206 	}
207 
208 	if (!psci_power_state_is_valid(*state)) {
209 		pr_warn("Invalid PSCI power state %#x\n", *state);
210 		return -EINVAL;
211 	}
212 
213 	return 0;
214 }
215 
psci_dt_cpu_init_topology(struct cpuidle_driver * drv,struct psci_cpuidle_data * data,unsigned int state_count,int cpu)216 static int psci_dt_cpu_init_topology(struct cpuidle_driver *drv,
217 				     struct psci_cpuidle_data *data,
218 				     unsigned int state_count, int cpu)
219 {
220 	/* Currently limit the hierarchical topology to be used in OSI mode. */
221 	if (!psci_has_osi_support())
222 		return 0;
223 
224 	if (IS_ENABLED(CONFIG_PREEMPT_RT))
225 		return 0;
226 
227 	data->dev = psci_dt_attach_cpu(cpu);
228 	if (IS_ERR_OR_NULL(data->dev))
229 		return PTR_ERR_OR_ZERO(data->dev);
230 
231 	/*
232 	 * Using the deepest state for the CPU to trigger a potential selection
233 	 * of a shared state for the domain, assumes the domain states are all
234 	 * deeper states.
235 	 */
236 	drv->states[state_count - 1].flags |= CPUIDLE_FLAG_RCU_IDLE;
237 	drv->states[state_count - 1].enter = psci_enter_domain_idle_state;
238 	drv->states[state_count - 1].enter_s2idle = psci_enter_s2idle_domain_idle_state;
239 	psci_cpuidle_use_cpuhp = true;
240 
241 	return 0;
242 }
243 
psci_dt_cpu_init_idle(struct device * dev,struct cpuidle_driver * drv,struct device_node * cpu_node,unsigned int state_count,int cpu)244 static int psci_dt_cpu_init_idle(struct device *dev, struct cpuidle_driver *drv,
245 				 struct device_node *cpu_node,
246 				 unsigned int state_count, int cpu)
247 {
248 	int i, ret = 0;
249 	u32 *psci_states;
250 	struct device_node *state_node;
251 	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
252 
253 	state_count++; /* Add WFI state too */
254 	psci_states = devm_kcalloc(dev, state_count, sizeof(*psci_states),
255 				   GFP_KERNEL);
256 	if (!psci_states)
257 		return -ENOMEM;
258 
259 	for (i = 1; i < state_count; i++) {
260 		state_node = of_get_cpu_state_node(cpu_node, i - 1);
261 		if (!state_node)
262 			break;
263 
264 		ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
265 		of_node_put(state_node);
266 
267 		if (ret)
268 			return ret;
269 
270 		pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
271 	}
272 
273 	if (i != state_count)
274 		return -ENODEV;
275 
276 	/* Initialize optional data, used for the hierarchical topology. */
277 	ret = psci_dt_cpu_init_topology(drv, data, state_count, cpu);
278 	if (ret < 0)
279 		return ret;
280 
281 	/* Idle states parsed correctly, store them in the per-cpu struct. */
282 	data->psci_states = psci_states;
283 	return 0;
284 }
285 
psci_cpu_init_idle(struct device * dev,struct cpuidle_driver * drv,unsigned int cpu,unsigned int state_count)286 static int psci_cpu_init_idle(struct device *dev, struct cpuidle_driver *drv,
287 			      unsigned int cpu, unsigned int state_count)
288 {
289 	struct device_node *cpu_node;
290 	int ret;
291 
292 	/*
293 	 * If the PSCI cpu_suspend function hook has not been initialized
294 	 * idle states must not be enabled, so bail out
295 	 */
296 	if (!psci_ops.cpu_suspend)
297 		return -EOPNOTSUPP;
298 
299 	cpu_node = of_cpu_device_node_get(cpu);
300 	if (!cpu_node)
301 		return -ENODEV;
302 
303 	ret = psci_dt_cpu_init_idle(dev, drv, cpu_node, state_count, cpu);
304 
305 	of_node_put(cpu_node);
306 
307 	return ret;
308 }
309 
psci_cpu_deinit_idle(int cpu)310 static void psci_cpu_deinit_idle(int cpu)
311 {
312 	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
313 
314 	psci_dt_detach_cpu(data->dev);
315 	psci_cpuidle_use_cpuhp = false;
316 }
317 
psci_idle_init_cpu(struct device * dev,int cpu)318 static int psci_idle_init_cpu(struct device *dev, int cpu)
319 {
320 	struct cpuidle_driver *drv;
321 	struct device_node *cpu_node;
322 	const char *enable_method;
323 	int ret = 0;
324 
325 	cpu_node = of_cpu_device_node_get(cpu);
326 	if (!cpu_node)
327 		return -ENODEV;
328 
329 	/*
330 	 * Check whether the enable-method for the cpu is PSCI, fail
331 	 * if it is not.
332 	 */
333 	enable_method = of_get_property(cpu_node, "enable-method", NULL);
334 	if (!enable_method || (strcmp(enable_method, "psci")))
335 		ret = -ENODEV;
336 
337 	of_node_put(cpu_node);
338 	if (ret)
339 		return ret;
340 
341 	drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
342 	if (!drv)
343 		return -ENOMEM;
344 
345 	drv->name = "psci_idle";
346 	drv->owner = THIS_MODULE;
347 	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
348 
349 	/*
350 	 * PSCI idle states relies on architectural WFI to be represented as
351 	 * state index 0.
352 	 */
353 	drv->states[0].enter = psci_enter_idle_state;
354 	drv->states[0].exit_latency = 1;
355 	drv->states[0].target_residency = 1;
356 	drv->states[0].power_usage = UINT_MAX;
357 	strcpy(drv->states[0].name, "WFI");
358 	strcpy(drv->states[0].desc, "ARM WFI");
359 
360 	/*
361 	 * If no DT idle states are detected (ret == 0) let the driver
362 	 * initialization fail accordingly since there is no reason to
363 	 * initialize the idle driver if only wfi is supported, the
364 	 * default archictectural back-end already executes wfi
365 	 * on idle entry.
366 	 */
367 	ret = dt_init_idle_driver(drv, psci_idle_state_match, 1);
368 	if (ret <= 0)
369 		return ret ? : -ENODEV;
370 
371 	/*
372 	 * Initialize PSCI idle states.
373 	 */
374 	ret = psci_cpu_init_idle(dev, drv, cpu, ret);
375 	if (ret) {
376 		pr_err("CPU %d failed to PSCI idle\n", cpu);
377 		return ret;
378 	}
379 
380 	ret = cpuidle_register(drv, NULL);
381 	if (ret)
382 		goto deinit;
383 
384 	cpuidle_cooling_register(drv);
385 
386 	return 0;
387 deinit:
388 	psci_cpu_deinit_idle(cpu);
389 	return ret;
390 }
391 
392 /*
393  * psci_idle_probe - Initializes PSCI cpuidle driver
394  *
395  * Initializes PSCI cpuidle driver for all CPUs, if any CPU fails
396  * to register cpuidle driver then rollback to cancel all CPUs
397  * registration.
398  */
psci_cpuidle_probe(struct platform_device * pdev)399 static int psci_cpuidle_probe(struct platform_device *pdev)
400 {
401 	int cpu, ret;
402 	struct cpuidle_driver *drv;
403 	struct cpuidle_device *dev;
404 
405 	for_each_possible_cpu(cpu) {
406 		ret = psci_idle_init_cpu(&pdev->dev, cpu);
407 		if (ret)
408 			goto out_fail;
409 	}
410 
411 	psci_idle_init_cpuhp();
412 	return 0;
413 
414 out_fail:
415 	while (--cpu >= 0) {
416 		dev = per_cpu(cpuidle_devices, cpu);
417 		drv = cpuidle_get_cpu_driver(dev);
418 		cpuidle_unregister(drv);
419 		psci_cpu_deinit_idle(cpu);
420 	}
421 
422 	return ret;
423 }
424 
425 static struct platform_driver psci_cpuidle_driver = {
426 	.probe = psci_cpuidle_probe,
427 	.driver = {
428 		.name = "psci-cpuidle",
429 	},
430 };
431 
psci_idle_init(void)432 static int __init psci_idle_init(void)
433 {
434 	struct platform_device *pdev;
435 	int ret;
436 
437 	ret = platform_driver_register(&psci_cpuidle_driver);
438 	if (ret)
439 		return ret;
440 
441 	pdev = platform_device_register_simple("psci-cpuidle", -1, NULL, 0);
442 	if (IS_ERR(pdev)) {
443 		platform_driver_unregister(&psci_cpuidle_driver);
444 		return PTR_ERR(pdev);
445 	}
446 
447 	return 0;
448 }
449 device_initcall(psci_idle_init);
450