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 	/* Do runtime PM to manage a hierarchical CPU toplogy. */
62 	pm_runtime_put_sync_suspend(pd_dev);
63 
64 	state = psci_get_domain_state();
65 	if (!state)
66 		state = states[idx];
67 
68 	ret = psci_enter_state(idx, state);
69 
70 	pm_runtime_get_sync(pd_dev);
71 
72 	/* Clear the domain state to start fresh when back from idle. */
73 	psci_set_domain_state(0);
74 	return ret;
75 }
76 
77 static int psci_idle_cpuhp_up(unsigned int cpu)
78 {
79 	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
80 
81 	if (pd_dev)
82 		pm_runtime_get_sync(pd_dev);
83 
84 	return 0;
85 }
86 
87 static int psci_idle_cpuhp_down(unsigned int cpu)
88 {
89 	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
90 
91 	if (pd_dev) {
92 		pm_runtime_put_sync(pd_dev);
93 		/* Clear domain state to start fresh at next online. */
94 		psci_set_domain_state(0);
95 	}
96 
97 	return 0;
98 }
99 
100 static void __init psci_idle_init_cpuhp(void)
101 {
102 	int err;
103 
104 	if (!psci_cpuidle_use_cpuhp)
105 		return;
106 
107 	err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
108 					"cpuidle/psci:online",
109 					psci_idle_cpuhp_up,
110 					psci_idle_cpuhp_down);
111 	if (err)
112 		pr_warn("Failed %d while setup cpuhp state\n", err);
113 }
114 
115 static int psci_enter_idle_state(struct cpuidle_device *dev,
116 				struct cpuidle_driver *drv, int idx)
117 {
118 	u32 *state = __this_cpu_read(psci_cpuidle_data.psci_states);
119 
120 	return psci_enter_state(idx, state[idx]);
121 }
122 
123 static struct cpuidle_driver psci_idle_driver __initdata = {
124 	.name = "psci_idle",
125 	.owner = THIS_MODULE,
126 	/*
127 	 * PSCI idle states relies on architectural WFI to
128 	 * be represented as state index 0.
129 	 */
130 	.states[0] = {
131 		.enter                  = psci_enter_idle_state,
132 		.exit_latency           = 1,
133 		.target_residency       = 1,
134 		.power_usage		= UINT_MAX,
135 		.name                   = "WFI",
136 		.desc                   = "ARM WFI",
137 	}
138 };
139 
140 static const struct of_device_id psci_idle_state_match[] __initconst = {
141 	{ .compatible = "arm,idle-state",
142 	  .data = psci_enter_idle_state },
143 	{ },
144 };
145 
146 int __init psci_dt_parse_state_node(struct device_node *np, u32 *state)
147 {
148 	int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
149 
150 	if (err) {
151 		pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
152 		return err;
153 	}
154 
155 	if (!psci_power_state_is_valid(*state)) {
156 		pr_warn("Invalid PSCI power state %#x\n", *state);
157 		return -EINVAL;
158 	}
159 
160 	return 0;
161 }
162 
163 static int __init psci_dt_cpu_init_idle(struct cpuidle_driver *drv,
164 					struct device_node *cpu_node,
165 					unsigned int state_count, int cpu)
166 {
167 	int i, ret = 0;
168 	u32 *psci_states;
169 	struct device_node *state_node;
170 	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
171 
172 	state_count++; /* Add WFI state too */
173 	psci_states = kcalloc(state_count, sizeof(*psci_states), GFP_KERNEL);
174 	if (!psci_states)
175 		return -ENOMEM;
176 
177 	for (i = 1; i < state_count; i++) {
178 		state_node = of_get_cpu_state_node(cpu_node, i - 1);
179 		if (!state_node)
180 			break;
181 
182 		ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
183 		of_node_put(state_node);
184 
185 		if (ret)
186 			goto free_mem;
187 
188 		pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
189 	}
190 
191 	if (i != state_count) {
192 		ret = -ENODEV;
193 		goto free_mem;
194 	}
195 
196 	/* Currently limit the hierarchical topology to be used in OSI mode. */
197 	if (psci_has_osi_support()) {
198 		data->dev = psci_dt_attach_cpu(cpu);
199 		if (IS_ERR(data->dev)) {
200 			ret = PTR_ERR(data->dev);
201 			goto free_mem;
202 		}
203 
204 		/*
205 		 * Using the deepest state for the CPU to trigger a potential
206 		 * selection of a shared state for the domain, assumes the
207 		 * domain states are all deeper states.
208 		 */
209 		if (data->dev) {
210 			drv->states[state_count - 1].enter =
211 				psci_enter_domain_idle_state;
212 			psci_cpuidle_use_cpuhp = true;
213 		}
214 	}
215 
216 	/* Idle states parsed correctly, store them in the per-cpu struct. */
217 	data->psci_states = psci_states;
218 	return 0;
219 
220 free_mem:
221 	kfree(psci_states);
222 	return ret;
223 }
224 
225 static __init int psci_cpu_init_idle(struct cpuidle_driver *drv,
226 				     unsigned int cpu, unsigned int state_count)
227 {
228 	struct device_node *cpu_node;
229 	int ret;
230 
231 	/*
232 	 * If the PSCI cpu_suspend function hook has not been initialized
233 	 * idle states must not be enabled, so bail out
234 	 */
235 	if (!psci_ops.cpu_suspend)
236 		return -EOPNOTSUPP;
237 
238 	cpu_node = of_cpu_device_node_get(cpu);
239 	if (!cpu_node)
240 		return -ENODEV;
241 
242 	ret = psci_dt_cpu_init_idle(drv, cpu_node, state_count, cpu);
243 
244 	of_node_put(cpu_node);
245 
246 	return ret;
247 }
248 
249 static int __init psci_idle_init_cpu(int cpu)
250 {
251 	struct cpuidle_driver *drv;
252 	struct device_node *cpu_node;
253 	const char *enable_method;
254 	int ret = 0;
255 
256 	cpu_node = of_cpu_device_node_get(cpu);
257 	if (!cpu_node)
258 		return -ENODEV;
259 
260 	/*
261 	 * Check whether the enable-method for the cpu is PSCI, fail
262 	 * if it is not.
263 	 */
264 	enable_method = of_get_property(cpu_node, "enable-method", NULL);
265 	if (!enable_method || (strcmp(enable_method, "psci")))
266 		ret = -ENODEV;
267 
268 	of_node_put(cpu_node);
269 	if (ret)
270 		return ret;
271 
272 	drv = kmemdup(&psci_idle_driver, sizeof(*drv), GFP_KERNEL);
273 	if (!drv)
274 		return -ENOMEM;
275 
276 	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
277 
278 	/*
279 	 * Initialize idle states data, starting at index 1, since
280 	 * by default idle state 0 is the quiescent state reached
281 	 * by the cpu by executing the wfi instruction.
282 	 *
283 	 * If no DT idle states are detected (ret == 0) let the driver
284 	 * initialization fail accordingly since there is no reason to
285 	 * initialize the idle driver if only wfi is supported, the
286 	 * default archictectural back-end already executes wfi
287 	 * on idle entry.
288 	 */
289 	ret = dt_init_idle_driver(drv, psci_idle_state_match, 1);
290 	if (ret <= 0) {
291 		ret = ret ? : -ENODEV;
292 		goto out_kfree_drv;
293 	}
294 
295 	/*
296 	 * Initialize PSCI idle states.
297 	 */
298 	ret = psci_cpu_init_idle(drv, cpu, ret);
299 	if (ret) {
300 		pr_err("CPU %d failed to PSCI idle\n", cpu);
301 		goto out_kfree_drv;
302 	}
303 
304 	ret = cpuidle_register(drv, NULL);
305 	if (ret)
306 		goto out_kfree_drv;
307 
308 	return 0;
309 
310 out_kfree_drv:
311 	kfree(drv);
312 	return ret;
313 }
314 
315 /*
316  * psci_idle_init - Initializes PSCI cpuidle driver
317  *
318  * Initializes PSCI cpuidle driver for all CPUs, if any CPU fails
319  * to register cpuidle driver then rollback to cancel all CPUs
320  * registration.
321  */
322 static int __init psci_idle_init(void)
323 {
324 	int cpu, ret;
325 	struct cpuidle_driver *drv;
326 	struct cpuidle_device *dev;
327 
328 	for_each_possible_cpu(cpu) {
329 		ret = psci_idle_init_cpu(cpu);
330 		if (ret)
331 			goto out_fail;
332 	}
333 
334 	psci_idle_init_cpuhp();
335 	return 0;
336 
337 out_fail:
338 	while (--cpu >= 0) {
339 		dev = per_cpu(cpuidle_devices, cpu);
340 		drv = cpuidle_get_cpu_driver(dev);
341 		cpuidle_unregister(drv);
342 		kfree(drv);
343 	}
344 
345 	return ret;
346 }
347 device_initcall(psci_idle_init);
348