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