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#include <linux/syscore_ops.h>
 27
 28#include <asm/cpuidle.h>
 29
 30#include "cpuidle-psci.h"
 31#include "dt_idle_states.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_cpuhp;
 41
 42void psci_set_domain_state(u32 state)
 43{
 44	__this_cpu_write(domain_state, state);
 45}
 46
 47static inline u32 psci_get_domain_state(void)
 48{
 49	return __this_cpu_read(domain_state);
 50}
 51
 52static inline int psci_enter_state(int idx, u32 state)
 53{
 54	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, idx, state);
 55}
 56
 57static int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
 58					  struct cpuidle_driver *drv, int idx,
 59					  bool s2idle)
 60{
 61	struct psci_cpuidle_data *data = this_cpu_ptr(&psci_cpuidle_data);
 62	u32 *states = data->psci_states;
 63	struct device *pd_dev = data->dev;
 64	u32 state;
 65	int ret;
 66
 67	ret = cpu_pm_enter();
 68	if (ret)
 69		return -1;
 70
 71	/* Do runtime PM to manage a hierarchical CPU toplogy. */
 72	ct_irq_enter_irqson();
 73	if (s2idle)
 74		dev_pm_genpd_suspend(pd_dev);
 75	else
 76		pm_runtime_put_sync_suspend(pd_dev);
 77	ct_irq_exit_irqson();
 78
 79	state = psci_get_domain_state();
 80	if (!state)
 81		state = states[idx];
 82
 83	ret = psci_cpu_suspend_enter(state) ? -1 : idx;
 84
 85	ct_irq_enter_irqson();
 86	if (s2idle)
 87		dev_pm_genpd_resume(pd_dev);
 88	else
 89		pm_runtime_get_sync(pd_dev);
 90	ct_irq_exit_irqson();
 91
 92	cpu_pm_exit();
 93
 94	/* Clear the domain state to start fresh when back from idle. */
 95	psci_set_domain_state(0);
 96	return ret;
 97}
 98
 99static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
100					struct cpuidle_driver *drv, int idx)
101{
102	return __psci_enter_domain_idle_state(dev, drv, idx, false);
103}
104
105static int psci_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
106					       struct cpuidle_driver *drv,
107					       int idx)
108{
109	return __psci_enter_domain_idle_state(dev, drv, idx, true);
110}
111
112static int psci_idle_cpuhp_up(unsigned int cpu)
113{
114	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
115
116	if (pd_dev)
117		pm_runtime_get_sync(pd_dev);
118
119	return 0;
120}
121
122static int psci_idle_cpuhp_down(unsigned int cpu)
123{
124	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
125
126	if (pd_dev) {
127		pm_runtime_put_sync(pd_dev);
128		/* Clear domain state to start fresh at next online. */
129		psci_set_domain_state(0);
130	}
131
132	return 0;
133}
134
135static void psci_idle_syscore_switch(bool suspend)
136{
137	bool cleared = false;
138	struct device *dev;
139	int cpu;
140
141	for_each_possible_cpu(cpu) {
142		dev = per_cpu_ptr(&psci_cpuidle_data, cpu)->dev;
143
144		if (dev && suspend) {
145			dev_pm_genpd_suspend(dev);
146		} else if (dev) {
147			dev_pm_genpd_resume(dev);
148
149			/* Account for userspace having offlined a CPU. */
150			if (pm_runtime_status_suspended(dev))
151				pm_runtime_set_active(dev);
152
153			/* Clear domain state to re-start fresh. */
154			if (!cleared) {
155				psci_set_domain_state(0);
156				cleared = true;
157			}
158		}
159	}
160}
161
162static int psci_idle_syscore_suspend(void)
163{
164	psci_idle_syscore_switch(true);
165	return 0;
166}
167
168static void psci_idle_syscore_resume(void)
169{
170	psci_idle_syscore_switch(false);
171}
172
173static struct syscore_ops psci_idle_syscore_ops = {
174	.suspend = psci_idle_syscore_suspend,
175	.resume = psci_idle_syscore_resume,
176};
177
178static void psci_idle_init_cpuhp(void)
179{
180	int err;
181
182	if (!psci_cpuidle_use_cpuhp)
183		return;
184
185	register_syscore_ops(&psci_idle_syscore_ops);
186
187	err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
188					"cpuidle/psci:online",
189					psci_idle_cpuhp_up,
190					psci_idle_cpuhp_down);
191	if (err)
192		pr_warn("Failed %d while setup cpuhp state\n", err);
193}
194
195static int psci_enter_idle_state(struct cpuidle_device *dev,
196				struct cpuidle_driver *drv, int idx)
197{
198	u32 *state = __this_cpu_read(psci_cpuidle_data.psci_states);
199
200	return psci_enter_state(idx, state[idx]);
201}
202
203static const struct of_device_id psci_idle_state_match[] = {
204	{ .compatible = "arm,idle-state",
205	  .data = psci_enter_idle_state },
206	{ },
207};
208
209int psci_dt_parse_state_node(struct device_node *np, u32 *state)
210{
211	int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
212
213	if (err) {
214		pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
215		return err;
216	}
217
218	if (!psci_power_state_is_valid(*state)) {
219		pr_warn("Invalid PSCI power state %#x\n", *state);
220		return -EINVAL;
221	}
222
223	return 0;
224}
225
226static int psci_dt_cpu_init_topology(struct cpuidle_driver *drv,
227				     struct psci_cpuidle_data *data,
228				     unsigned int state_count, int cpu)
229{
230	/* Currently limit the hierarchical topology to be used in OSI mode. */
231	if (!psci_has_osi_support())
232		return 0;
233
234	data->dev = psci_dt_attach_cpu(cpu);
235	if (IS_ERR_OR_NULL(data->dev))
236		return PTR_ERR_OR_ZERO(data->dev);
237
238	/*
239	 * Using the deepest state for the CPU to trigger a potential selection
240	 * of a shared state for the domain, assumes the domain states are all
241	 * deeper states.
242	 */
243	drv->states[state_count - 1].enter = psci_enter_domain_idle_state;
244	drv->states[state_count - 1].enter_s2idle = psci_enter_s2idle_domain_idle_state;
245	psci_cpuidle_use_cpuhp = true;
246
247	return 0;
248}
249
250static int psci_dt_cpu_init_idle(struct device *dev, struct cpuidle_driver *drv,
251				 struct device_node *cpu_node,
252				 unsigned int state_count, int cpu)
253{
254	int i, ret = 0;
255	u32 *psci_states;
256	struct device_node *state_node;
257	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
258
259	state_count++; /* Add WFI state too */
260	psci_states = devm_kcalloc(dev, state_count, sizeof(*psci_states),
261				   GFP_KERNEL);
262	if (!psci_states)
263		return -ENOMEM;
264
265	for (i = 1; i < state_count; i++) {
266		state_node = of_get_cpu_state_node(cpu_node, i - 1);
267		if (!state_node)
268			break;
269
270		ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
271		of_node_put(state_node);
272
273		if (ret)
274			return ret;
275
276		pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
277	}
278
279	if (i != state_count)
280		return -ENODEV;
281
282	/* Initialize optional data, used for the hierarchical topology. */
283	ret = psci_dt_cpu_init_topology(drv, data, state_count, cpu);
284	if (ret < 0)
285		return ret;
286
287	/* Idle states parsed correctly, store them in the per-cpu struct. */
288	data->psci_states = psci_states;
289	return 0;
290}
291
292static int psci_cpu_init_idle(struct device *dev, struct cpuidle_driver *drv,
293			      unsigned int cpu, unsigned int state_count)
294{
295	struct device_node *cpu_node;
296	int ret;
297
298	/*
299	 * If the PSCI cpu_suspend function hook has not been initialized
300	 * idle states must not be enabled, so bail out
301	 */
302	if (!psci_ops.cpu_suspend)
303		return -EOPNOTSUPP;
304
305	cpu_node = of_cpu_device_node_get(cpu);
306	if (!cpu_node)
307		return -ENODEV;
308
309	ret = psci_dt_cpu_init_idle(dev, drv, cpu_node, state_count, cpu);
310
311	of_node_put(cpu_node);
312
313	return ret;
314}
315
316static void psci_cpu_deinit_idle(int cpu)
317{
318	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
319
320	psci_dt_detach_cpu(data->dev);
321	psci_cpuidle_use_cpuhp = false;
322}
323
324static int psci_idle_init_cpu(struct device *dev, int cpu)
325{
326	struct cpuidle_driver *drv;
327	struct device_node *cpu_node;
328	const char *enable_method;
329	int ret = 0;
330
331	cpu_node = of_cpu_device_node_get(cpu);
332	if (!cpu_node)
333		return -ENODEV;
334
335	/*
336	 * Check whether the enable-method for the cpu is PSCI, fail
337	 * if it is not.
338	 */
339	enable_method = of_get_property(cpu_node, "enable-method", NULL);
340	if (!enable_method || (strcmp(enable_method, "psci")))
341		ret = -ENODEV;
342
343	of_node_put(cpu_node);
344	if (ret)
345		return ret;
346
347	drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
348	if (!drv)
349		return -ENOMEM;
350
351	drv->name = "psci_idle";
352	drv->owner = THIS_MODULE;
353	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
354
355	/*
356	 * PSCI idle states relies on architectural WFI to be represented as
357	 * state index 0.
358	 */
359	drv->states[0].enter = psci_enter_idle_state;
360	drv->states[0].exit_latency = 1;
361	drv->states[0].target_residency = 1;
362	drv->states[0].power_usage = UINT_MAX;
363	strcpy(drv->states[0].name, "WFI");
364	strcpy(drv->states[0].desc, "ARM WFI");
365
366	/*
367	 * If no DT idle states are detected (ret == 0) let the driver
368	 * initialization fail accordingly since there is no reason to
369	 * initialize the idle driver if only wfi is supported, the
370	 * default archictectural back-end already executes wfi
371	 * on idle entry.
372	 */
373	ret = dt_init_idle_driver(drv, psci_idle_state_match, 1);
374	if (ret <= 0)
375		return ret ? : -ENODEV;
376
377	/*
378	 * Initialize PSCI idle states.
379	 */
380	ret = psci_cpu_init_idle(dev, drv, cpu, ret);
381	if (ret) {
382		pr_err("CPU %d failed to PSCI idle\n", cpu);
383		return ret;
384	}
385
386	ret = cpuidle_register(drv, NULL);
387	if (ret)
388		goto deinit;
389
390	cpuidle_cooling_register(drv);
391
392	return 0;
393deinit:
394	psci_cpu_deinit_idle(cpu);
395	return ret;
396}
397
398/*
399 * psci_idle_probe - Initializes PSCI cpuidle driver
400 *
401 * Initializes PSCI cpuidle driver for all CPUs, if any CPU fails
402 * to register cpuidle driver then rollback to cancel all CPUs
403 * registration.
404 */
405static int psci_cpuidle_probe(struct platform_device *pdev)
406{
407	int cpu, ret;
408	struct cpuidle_driver *drv;
409	struct cpuidle_device *dev;
410
411	for_each_possible_cpu(cpu) {
412		ret = psci_idle_init_cpu(&pdev->dev, cpu);
413		if (ret)
414			goto out_fail;
415	}
416
417	psci_idle_init_cpuhp();
418	return 0;
419
420out_fail:
421	while (--cpu >= 0) {
422		dev = per_cpu(cpuidle_devices, cpu);
423		drv = cpuidle_get_cpu_driver(dev);
424		cpuidle_unregister(drv);
425		psci_cpu_deinit_idle(cpu);
426	}
427
428	return ret;
429}
430
431static struct platform_driver psci_cpuidle_driver = {
432	.probe = psci_cpuidle_probe,
433	.driver = {
434		.name = "psci-cpuidle",
435	},
436};
437
438static int __init psci_idle_init(void)
439{
440	struct platform_device *pdev;
441	int ret;
442
443	ret = platform_driver_register(&psci_cpuidle_driver);
444	if (ret)
445		return ret;
446
447	pdev = platform_device_register_simple("psci-cpuidle", -1, NULL, 0);
448	if (IS_ERR(pdev)) {
449		platform_driver_unregister(&psci_cpuidle_driver);
450		return PTR_ERR(pdev);
451	}
452
453	return 0;
454}
455device_initcall(psci_idle_init);