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