cpuidle-psci.c

  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/device/faux.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#include <trace/events/power.h>
 29
 30#include "cpuidle-psci.h"
 31#include "dt_idle_states.h"
 32#include "dt_idle_genpd.h"
 33
 34struct psci_cpuidle_data {
 35	u32 *psci_states;
 36	struct device *dev;
 37};
 38
 39struct psci_cpuidle_domain_state {
 40	struct generic_pm_domain *pd;
 41	unsigned int state_idx;
 42	u32 state;
 43};
 44
 45static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
 46static DEFINE_PER_CPU(struct psci_cpuidle_domain_state, psci_domain_state);
 47static bool psci_cpuidle_use_syscore;
 48
 49void psci_set_domain_state(struct generic_pm_domain *pd, unsigned int state_idx,
 50			   u32 state)
 51{
 52	struct psci_cpuidle_domain_state *ds = this_cpu_ptr(&psci_domain_state);
 53
 54	ds->pd = pd;
 55	ds->state_idx = state_idx;
 56	ds->state = state;
 57}
 58
 59static inline void psci_clear_domain_state(void)
 60{
 61	__this_cpu_write(psci_domain_state.state, 0);
 62}
 63
 64static __cpuidle int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
 65						    struct cpuidle_driver *drv, int idx,
 66						    bool s2idle)
 67{
 68	struct psci_cpuidle_data *data = this_cpu_ptr(&psci_cpuidle_data);
 69	u32 *states = data->psci_states;
 70	struct device *pd_dev = data->dev;
 71	struct psci_cpuidle_domain_state *ds;
 72	u32 state = states[idx];
 73	int ret;
 74
 75	ret = cpu_pm_enter();
 76	if (ret)
 77		return -1;
 78
 79	/* Do runtime PM to manage a hierarchical CPU toplogy. */
 80	if (s2idle)
 81		dev_pm_genpd_suspend(pd_dev);
 82	else
 83		pm_runtime_put_sync_suspend(pd_dev);
 84
 85	ds = this_cpu_ptr(&psci_domain_state);
 86	if (ds->state)
 87		state = ds->state;
 88
 89	trace_psci_domain_idle_enter(dev->cpu, state, s2idle);
 90	ret = psci_cpu_suspend_enter(state) ? -1 : idx;
 91	trace_psci_domain_idle_exit(dev->cpu, state, s2idle);
 92
 93	if (s2idle)
 94		dev_pm_genpd_resume(pd_dev);
 95	else
 96		pm_runtime_get_sync(pd_dev);
 97
 98	cpu_pm_exit();
 99
100	/* Correct domain-idlestate statistics if we failed to enter. */
101	if (ret == -1 && ds->state)
102		pm_genpd_inc_rejected(ds->pd, ds->state_idx);
103
104	/* Clear the domain state to start fresh when back from idle. */
105	psci_clear_domain_state();
106	return ret;
107}
108
109static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
110					struct cpuidle_driver *drv, int idx)
111{
112	return __psci_enter_domain_idle_state(dev, drv, idx, false);
113}
114
115static int psci_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
116					       struct cpuidle_driver *drv,
117					       int idx)
118{
119	return __psci_enter_domain_idle_state(dev, drv, idx, true);
120}
121
122static int psci_idle_cpuhp_up(unsigned int cpu)
123{
124	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
125
126	if (pd_dev) {
127		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
128			pm_runtime_get_sync(pd_dev);
129		else
130			dev_pm_genpd_resume(pd_dev);
131	}
132
133	return 0;
134}
135
136static int psci_idle_cpuhp_down(unsigned int cpu)
137{
138	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
139
140	if (pd_dev) {
141		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
142			pm_runtime_put_sync(pd_dev);
143		else
144			dev_pm_genpd_suspend(pd_dev);
145
146		/* Clear domain state to start fresh at next online. */
147		psci_clear_domain_state();
148	}
149
150	return 0;
151}
152
153static void psci_idle_syscore_switch(bool suspend)
154{
155	bool cleared = false;
156	struct device *dev;
157	int cpu;
158
159	for_each_possible_cpu(cpu) {
160		dev = per_cpu_ptr(&psci_cpuidle_data, cpu)->dev;
161
162		if (dev && suspend) {
163			dev_pm_genpd_suspend(dev);
164		} else if (dev) {
165			dev_pm_genpd_resume(dev);
166
167			/* Account for userspace having offlined a CPU. */
168			if (pm_runtime_status_suspended(dev))
169				pm_runtime_set_active(dev);
170
171			/* Clear domain state to re-start fresh. */
172			if (!cleared) {
173				psci_clear_domain_state();
174				cleared = true;
175			}
176		}
177	}
178}
179
180static int psci_idle_syscore_suspend(void *data)
181{
182	psci_idle_syscore_switch(true);
183	return 0;
184}
185
186static void psci_idle_syscore_resume(void *data)
187{
188	psci_idle_syscore_switch(false);
189}
190
191static const struct syscore_ops psci_idle_syscore_ops = {
192	.suspend = psci_idle_syscore_suspend,
193	.resume = psci_idle_syscore_resume,
194};
195
196static struct syscore psci_idle_syscore = {
197	.ops = &psci_idle_syscore_ops,
198};
199
200static void psci_idle_init_syscore(void)
201{
202	if (psci_cpuidle_use_syscore)
203		register_syscore(&psci_idle_syscore);
204}
205
206static void psci_idle_init_cpuhp(void)
207{
208	int err;
209
210	err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
211					"cpuidle/psci:online",
212					psci_idle_cpuhp_up,
213					psci_idle_cpuhp_down);
214	if (err)
215		pr_warn("Failed %d while setup cpuhp state\n", err);
216}
217
218static __cpuidle int psci_enter_idle_state(struct cpuidle_device *dev,
219					   struct cpuidle_driver *drv, int idx)
220{
221	u32 *state = __this_cpu_read(psci_cpuidle_data.psci_states);
222
223	return CPU_PM_CPU_IDLE_ENTER_PARAM_RCU(psci_cpu_suspend_enter, idx, state[idx]);
224}
225
226static const struct of_device_id psci_idle_state_match[] = {
227	{ .compatible = "arm,idle-state",
228	  .data = psci_enter_idle_state },
229	{ },
230};
231
232int psci_dt_parse_state_node(struct device_node *np, u32 *state)
233{
234	int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
235
236	if (err) {
237		pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
238		return err;
239	}
240
241	if (!psci_power_state_is_valid(*state)) {
242		pr_warn("Invalid PSCI power state %#x\n", *state);
243		return -EINVAL;
244	}
245
246	return 0;
247}
248
249static int psci_dt_cpu_init_topology(struct cpuidle_driver *drv,
250				     struct psci_cpuidle_data *data,
251				     unsigned int state_count, int cpu)
252{
253	/* Currently limit the hierarchical topology to be used in OSI mode. */
254	if (!psci_has_osi_support())
255		return 0;
256
257	data->dev = dt_idle_attach_cpu(cpu, "psci");
258	if (IS_ERR_OR_NULL(data->dev))
259		return PTR_ERR_OR_ZERO(data->dev);
260
261	psci_cpuidle_use_syscore = true;
262
263	/*
264	 * Using the deepest state for the CPU to trigger a potential selection
265	 * of a shared state for the domain, assumes the domain states are all
266	 * deeper states. On PREEMPT_RT the hierarchical topology is limited to
267	 * s2ram and s2idle.
268	 */
269	drv->states[state_count - 1].enter_s2idle = psci_enter_s2idle_domain_idle_state;
270	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
271		drv->states[state_count - 1].enter = psci_enter_domain_idle_state;
272
273	return 0;
274}
275
276static int psci_dt_cpu_init_idle(struct device *dev, struct cpuidle_driver *drv,
277				 struct device_node *cpu_node,
278				 unsigned int state_count, int cpu)
279{
280	int i, ret = 0;
281	u32 *psci_states;
282	struct device_node *state_node;
283	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
284
285	state_count++; /* Add WFI state too */
286	psci_states = devm_kcalloc(dev, state_count, sizeof(*psci_states),
287				   GFP_KERNEL);
288	if (!psci_states)
289		return -ENOMEM;
290
291	for (i = 1; i < state_count; i++) {
292		state_node = of_get_cpu_state_node(cpu_node, i - 1);
293		if (!state_node)
294			break;
295
296		ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
297		of_node_put(state_node);
298
299		if (ret)
300			return ret;
301
302		pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
303	}
304
305	if (i != state_count)
306		return -ENODEV;
307
308	/* Initialize optional data, used for the hierarchical topology. */
309	ret = psci_dt_cpu_init_topology(drv, data, state_count, cpu);
310	if (ret < 0)
311		return ret;
312
313	/* Idle states parsed correctly, store them in the per-cpu struct. */
314	data->psci_states = psci_states;
315	return 0;
316}
317
318static int psci_cpu_init_idle(struct device *dev, struct cpuidle_driver *drv,
319			      unsigned int cpu, unsigned int state_count)
320{
321	struct device_node *cpu_node;
322	int ret;
323
324	/*
325	 * If the PSCI cpu_suspend function hook has not been initialized
326	 * idle states must not be enabled, so bail out
327	 */
328	if (!psci_ops.cpu_suspend)
329		return -EOPNOTSUPP;
330
331	cpu_node = of_cpu_device_node_get(cpu);
332	if (!cpu_node)
333		return -ENODEV;
334
335	ret = psci_dt_cpu_init_idle(dev, drv, cpu_node, state_count, cpu);
336
337	of_node_put(cpu_node);
338
339	return ret;
340}
341
342static void psci_cpu_deinit_idle(int cpu)
343{
344	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
345
346	dt_idle_detach_cpu(data->dev);
347	psci_cpuidle_use_syscore = false;
348}
349
350static int psci_idle_init_cpu(struct device *dev, int cpu)
351{
352	struct cpuidle_driver *drv;
353	struct device_node *cpu_node;
354	const char *enable_method;
355	int ret = 0;
356
357	cpu_node = of_cpu_device_node_get(cpu);
358	if (!cpu_node)
359		return -ENODEV;
360
361	/*
362	 * Check whether the enable-method for the cpu is PSCI, fail
363	 * if it is not.
364	 */
365	enable_method = of_get_property(cpu_node, "enable-method", NULL);
366	if (!enable_method || (strcmp(enable_method, "psci")))
367		ret = -ENODEV;
368
369	of_node_put(cpu_node);
370	if (ret)
371		return ret;
372
373	drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
374	if (!drv)
375		return -ENOMEM;
376
377	drv->name = "psci_idle";
378	drv->owner = THIS_MODULE;
379	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
380
381	/*
382	 * PSCI idle states relies on architectural WFI to be represented as
383	 * state index 0.
384	 */
385	drv->states[0].enter = psci_enter_idle_state;
386	drv->states[0].exit_latency = 1;
387	drv->states[0].target_residency = 1;
388	drv->states[0].power_usage = UINT_MAX;
389	strscpy(drv->states[0].name, "WFI");
390	strscpy(drv->states[0].desc, "ARM WFI");
391
392	/*
393	 * If no DT idle states are detected (ret == 0) let the driver
394	 * initialization fail accordingly since there is no reason to
395	 * initialize the idle driver if only wfi is supported, the
396	 * default archictectural back-end already executes wfi
397	 * on idle entry.
398	 */
399	ret = dt_init_idle_driver(drv, psci_idle_state_match, 1);
400	if (ret <= 0)
401		return ret ? : -ENODEV;
402
403	/*
404	 * Initialize PSCI idle states.
405	 */
406	ret = psci_cpu_init_idle(dev, drv, cpu, ret);
407	if (ret) {
408		pr_err("CPU %d failed to PSCI idle\n", cpu);
409		return ret;
410	}
411
412	ret = cpuidle_register(drv, NULL);
413	if (ret)
414		goto deinit;
415
416	cpuidle_cooling_register(drv);
417
418	return 0;
419deinit:
420	psci_cpu_deinit_idle(cpu);
421	return ret;
422}
423
424/*
425 * psci_idle_probe - Initializes PSCI cpuidle driver
426 *
427 * Initializes PSCI cpuidle driver for all present CPUs, if any CPU fails
428 * to register cpuidle driver then rollback to cancel all CPUs
429 * registration.
430 */
431static int psci_cpuidle_probe(struct faux_device *fdev)
432{
433	int cpu, ret;
434	struct cpuidle_driver *drv;
435	struct cpuidle_device *dev;
436
437	for_each_present_cpu(cpu) {
438		ret = psci_idle_init_cpu(&fdev->dev, cpu);
439		if (ret)
440			goto out_fail;
441	}
442
443	psci_idle_init_syscore();
444	psci_idle_init_cpuhp();
445	return 0;
446
447out_fail:
448	while (--cpu >= 0) {
449		dev = per_cpu(cpuidle_devices, cpu);
450		drv = cpuidle_get_cpu_driver(dev);
451		cpuidle_unregister(drv);
452		psci_cpu_deinit_idle(cpu);
453	}
454
455	return ret;
456}
457
458static struct faux_device_ops psci_cpuidle_ops = {
459	.probe = psci_cpuidle_probe,
460};
461
462static bool __init dt_idle_state_present(void)
463{
464	struct device_node *cpu_node __free(device_node) =
465			of_cpu_device_node_get(cpumask_first(cpu_possible_mask));
466	if (!cpu_node)
467		return false;
468
469	struct device_node *state_node __free(device_node) =
470			of_get_cpu_state_node(cpu_node, 0);
471	if (!state_node)
472		return false;
473
474	return !!of_match_node(psci_idle_state_match, state_node);
475}
476
477static int __init psci_idle_init(void)
478{
479	struct faux_device *fdev;
480
481	if (!dt_idle_state_present())
482		return 0;
483
484	fdev = faux_device_create("psci-cpuidle", NULL, &psci_cpuidle_ops);
485	if (!fdev) {
486		pr_err("Failed to create psci-cpuidle device\n");
487		return -ENODEV;
488	}
489
490	return 0;
491}
492device_initcall(psci_idle_init);