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/cpuidle.h>
13 #include <linux/cpumask.h>
14 #include <linux/cpu_pm.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/of_device.h>
19 #include <linux/psci.h>
20 #include <linux/pm_runtime.h>
21 #include <linux/slab.h>
22 
23 #include <asm/cpuidle.h>
24 
25 #include "cpuidle-psci.h"
26 #include "dt_idle_states.h"
27 
28 struct psci_cpuidle_data {
29 	u32 *psci_states;
30 	struct device *dev;
31 };
32 
33 static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
34 static DEFINE_PER_CPU(u32, domain_state);
35 static bool psci_cpuidle_use_cpuhp __initdata;
36 
37 void psci_set_domain_state(u32 state)
38 {
39 	__this_cpu_write(domain_state, state);
40 }
41 
42 static inline u32 psci_get_domain_state(void)
43 {
44 	return __this_cpu_read(domain_state);
45 }
46 
47 static inline int psci_enter_state(int idx, u32 state)
48 {
49 	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, idx, state);
50 }
51 
52 static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
53 					struct cpuidle_driver *drv, int idx)
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 	pm_runtime_put_sync_suspend(pd_dev);
67 
68 	state = psci_get_domain_state();
69 	if (!state)
70 		state = states[idx];
71 
72 	ret = psci_cpu_suspend_enter(state) ? -1 : idx;
73 
74 	pm_runtime_get_sync(pd_dev);
75 
76 	cpu_pm_exit();
77 
78 	/* Clear the domain state to start fresh when back from idle. */
79 	psci_set_domain_state(0);
80 	return ret;
81 }
82 
83 static int psci_idle_cpuhp_up(unsigned int cpu)
84 {
85 	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
86 
87 	if (pd_dev)
88 		pm_runtime_get_sync(pd_dev);
89 
90 	return 0;
91 }
92 
93 static int psci_idle_cpuhp_down(unsigned int cpu)
94 {
95 	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
96 
97 	if (pd_dev) {
98 		pm_runtime_put_sync(pd_dev);
99 		/* Clear domain state to start fresh at next online. */
100 		psci_set_domain_state(0);
101 	}
102 
103 	return 0;
104 }
105 
106 static void __init psci_idle_init_cpuhp(void)
107 {
108 	int err;
109 
110 	if (!psci_cpuidle_use_cpuhp)
111 		return;
112 
113 	err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
114 					"cpuidle/psci:online",
115 					psci_idle_cpuhp_up,
116 					psci_idle_cpuhp_down);
117 	if (err)
118 		pr_warn("Failed %d while setup cpuhp state\n", err);
119 }
120 
121 static int psci_enter_idle_state(struct cpuidle_device *dev,
122 				struct cpuidle_driver *drv, int idx)
123 {
124 	u32 *state = __this_cpu_read(psci_cpuidle_data.psci_states);
125 
126 	return psci_enter_state(idx, state[idx]);
127 }
128 
129 static struct cpuidle_driver psci_idle_driver __initdata = {
130 	.name = "psci_idle",
131 	.owner = THIS_MODULE,
132 	/*
133 	 * PSCI idle states relies on architectural WFI to
134 	 * be represented as state index 0.
135 	 */
136 	.states[0] = {
137 		.enter                  = psci_enter_idle_state,
138 		.exit_latency           = 1,
139 		.target_residency       = 1,
140 		.power_usage		= UINT_MAX,
141 		.name                   = "WFI",
142 		.desc                   = "ARM WFI",
143 	}
144 };
145 
146 static const struct of_device_id psci_idle_state_match[] __initconst = {
147 	{ .compatible = "arm,idle-state",
148 	  .data = psci_enter_idle_state },
149 	{ },
150 };
151 
152 int __init psci_dt_parse_state_node(struct device_node *np, u32 *state)
153 {
154 	int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
155 
156 	if (err) {
157 		pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
158 		return err;
159 	}
160 
161 	if (!psci_power_state_is_valid(*state)) {
162 		pr_warn("Invalid PSCI power state %#x\n", *state);
163 		return -EINVAL;
164 	}
165 
166 	return 0;
167 }
168 
169 static int __init psci_dt_cpu_init_topology(struct cpuidle_driver *drv,
170 					    struct psci_cpuidle_data *data,
171 					    unsigned int state_count, int cpu)
172 {
173 	/* Currently limit the hierarchical topology to be used in OSI mode. */
174 	if (!psci_has_osi_support())
175 		return 0;
176 
177 	data->dev = psci_dt_attach_cpu(cpu);
178 	if (IS_ERR_OR_NULL(data->dev))
179 		return PTR_ERR_OR_ZERO(data->dev);
180 
181 	/*
182 	 * Using the deepest state for the CPU to trigger a potential selection
183 	 * of a shared state for the domain, assumes the domain states are all
184 	 * deeper states.
185 	 */
186 	drv->states[state_count - 1].enter = psci_enter_domain_idle_state;
187 	psci_cpuidle_use_cpuhp = true;
188 
189 	return 0;
190 }
191 
192 static int __init psci_dt_cpu_init_idle(struct cpuidle_driver *drv,
193 					struct device_node *cpu_node,
194 					unsigned int state_count, int cpu)
195 {
196 	int i, ret = 0;
197 	u32 *psci_states;
198 	struct device_node *state_node;
199 	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
200 
201 	state_count++; /* Add WFI state too */
202 	psci_states = kcalloc(state_count, sizeof(*psci_states), GFP_KERNEL);
203 	if (!psci_states)
204 		return -ENOMEM;
205 
206 	for (i = 1; i < state_count; i++) {
207 		state_node = of_get_cpu_state_node(cpu_node, i - 1);
208 		if (!state_node)
209 			break;
210 
211 		ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
212 		of_node_put(state_node);
213 
214 		if (ret)
215 			goto free_mem;
216 
217 		pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
218 	}
219 
220 	if (i != state_count) {
221 		ret = -ENODEV;
222 		goto free_mem;
223 	}
224 
225 	/* Initialize optional data, used for the hierarchical topology. */
226 	ret = psci_dt_cpu_init_topology(drv, data, state_count, cpu);
227 	if (ret < 0)
228 		goto free_mem;
229 
230 	/* Idle states parsed correctly, store them in the per-cpu struct. */
231 	data->psci_states = psci_states;
232 	return 0;
233 
234 free_mem:
235 	kfree(psci_states);
236 	return ret;
237 }
238 
239 static __init int psci_cpu_init_idle(struct cpuidle_driver *drv,
240 				     unsigned int cpu, unsigned int state_count)
241 {
242 	struct device_node *cpu_node;
243 	int ret;
244 
245 	/*
246 	 * If the PSCI cpu_suspend function hook has not been initialized
247 	 * idle states must not be enabled, so bail out
248 	 */
249 	if (!psci_ops.cpu_suspend)
250 		return -EOPNOTSUPP;
251 
252 	cpu_node = of_cpu_device_node_get(cpu);
253 	if (!cpu_node)
254 		return -ENODEV;
255 
256 	ret = psci_dt_cpu_init_idle(drv, cpu_node, state_count, cpu);
257 
258 	of_node_put(cpu_node);
259 
260 	return ret;
261 }
262 
263 static int __init psci_idle_init_cpu(int cpu)
264 {
265 	struct cpuidle_driver *drv;
266 	struct device_node *cpu_node;
267 	const char *enable_method;
268 	int ret = 0;
269 
270 	cpu_node = of_cpu_device_node_get(cpu);
271 	if (!cpu_node)
272 		return -ENODEV;
273 
274 	/*
275 	 * Check whether the enable-method for the cpu is PSCI, fail
276 	 * if it is not.
277 	 */
278 	enable_method = of_get_property(cpu_node, "enable-method", NULL);
279 	if (!enable_method || (strcmp(enable_method, "psci")))
280 		ret = -ENODEV;
281 
282 	of_node_put(cpu_node);
283 	if (ret)
284 		return ret;
285 
286 	drv = kmemdup(&psci_idle_driver, sizeof(*drv), GFP_KERNEL);
287 	if (!drv)
288 		return -ENOMEM;
289 
290 	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
291 
292 	/*
293 	 * Initialize idle states data, starting at index 1, since
294 	 * by default idle state 0 is the quiescent state reached
295 	 * by the cpu by executing the wfi instruction.
296 	 *
297 	 * If no DT idle states are detected (ret == 0) let the driver
298 	 * initialization fail accordingly since there is no reason to
299 	 * initialize the idle driver if only wfi is supported, the
300 	 * default archictectural back-end already executes wfi
301 	 * on idle entry.
302 	 */
303 	ret = dt_init_idle_driver(drv, psci_idle_state_match, 1);
304 	if (ret <= 0) {
305 		ret = ret ? : -ENODEV;
306 		goto out_kfree_drv;
307 	}
308 
309 	/*
310 	 * Initialize PSCI idle states.
311 	 */
312 	ret = psci_cpu_init_idle(drv, cpu, ret);
313 	if (ret) {
314 		pr_err("CPU %d failed to PSCI idle\n", cpu);
315 		goto out_kfree_drv;
316 	}
317 
318 	ret = cpuidle_register(drv, NULL);
319 	if (ret)
320 		goto out_kfree_drv;
321 
322 	return 0;
323 
324 out_kfree_drv:
325 	kfree(drv);
326 	return ret;
327 }
328 
329 /*
330  * psci_idle_init - Initializes PSCI cpuidle driver
331  *
332  * Initializes PSCI cpuidle driver for all CPUs, if any CPU fails
333  * to register cpuidle driver then rollback to cancel all CPUs
334  * registration.
335  */
336 static int __init psci_idle_init(void)
337 {
338 	int cpu, ret;
339 	struct cpuidle_driver *drv;
340 	struct cpuidle_device *dev;
341 
342 	for_each_possible_cpu(cpu) {
343 		ret = psci_idle_init_cpu(cpu);
344 		if (ret)
345 			goto out_fail;
346 	}
347 
348 	psci_idle_init_cpuhp();
349 	return 0;
350 
351 out_fail:
352 	while (--cpu >= 0) {
353 		dev = per_cpu(cpuidle_devices, cpu);
354 		drv = cpuidle_get_cpu_driver(dev);
355 		cpuidle_unregister(drv);
356 		kfree(drv);
357 	}
358 
359 	return ret;
360 }
361 device_initcall(psci_idle_init);
362