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
32struct psci_cpuidle_data {
33	u32 *psci_states;
34	struct device *dev;
35};
36
37static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
38static DEFINE_PER_CPU(u32, domain_state);
39static bool psci_cpuidle_use_cpuhp;
40
41void psci_set_domain_state(u32 state)
42{
43	__this_cpu_write(domain_state, state);
44}
45
46static inline u32 psci_get_domain_state(void)
47{
48	return __this_cpu_read(domain_state);
49}
50
51static __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
89static 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
95static 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
102static 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
112static 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
125static 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
152static int psci_idle_syscore_suspend(void)
153{
154	psci_idle_syscore_switch(true);
155	return 0;
156}
157
158static void psci_idle_syscore_resume(void)
159{
160	psci_idle_syscore_switch(false);
161}
162
163static struct syscore_ops psci_idle_syscore_ops = {
164	.suspend = psci_idle_syscore_suspend,
165	.resume = psci_idle_syscore_resume,
166};
167
168static 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
185static __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
193static const struct of_device_id psci_idle_state_match[] = {
194	{ .compatible = "arm,idle-state",
195	  .data = psci_enter_idle_state },
196	{ },
197};
198
199int 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
216static 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
244static 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
286static 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
310static 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
318static 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;
387deinit:
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 */
399static 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
414out_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
425static struct platform_driver psci_cpuidle_driver = {
426	.probe = psci_cpuidle_probe,
427	.driver = {
428		.name = "psci-cpuidle",
429	},
430};
431
432static 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}
449device_initcall(psci_idle_init);
450