1 // SPDX-License-Identifier: GPL-2.0-only
3 * PSCI CPU idle driver.
5 * Copyright (C) 2019 ARM Ltd.
6 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
9 #define pr_fmt(fmt) "CPUidle PSCI: " fmt
11 #include <linux/cpuidle.h>
12 #include <linux/cpumask.h>
13 #include <linux/cpu_pm.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
17 #include <linux/of_device.h>
18 #include <linux/psci.h>
19 #include <linux/slab.h>
21 #include <asm/cpuidle.h>
23 #include "dt_idle_states.h"
25 static DEFINE_PER_CPU_READ_MOSTLY(u32 *, psci_power_state);
27 static int psci_enter_idle_state(struct cpuidle_device *dev,
28 struct cpuidle_driver *drv, int idx)
30 u32 *state = __this_cpu_read(psci_power_state);
32 return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter,
36 static struct cpuidle_driver psci_idle_driver __initdata = {
40 * PSCI idle states relies on architectural WFI to
41 * be represented as state index 0.
44 .enter = psci_enter_idle_state,
46 .target_residency = 1,
47 .power_usage = UINT_MAX,
53 static const struct of_device_id psci_idle_state_match[] __initconst = {
54 { .compatible = "arm,idle-state",
55 .data = psci_enter_idle_state },
59 static int __init psci_dt_parse_state_node(struct device_node *np, u32 *state)
61 int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
64 pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
68 if (!psci_power_state_is_valid(*state)) {
69 pr_warn("Invalid PSCI power state %#x\n", *state);
76 static int __init psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
78 int i, ret = 0, count = 0;
80 struct device_node *state_node;
82 /* Count idle states */
83 while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
86 of_node_put(state_node);
92 psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
96 for (i = 0; i < count; i++) {
97 state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
98 ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
99 of_node_put(state_node);
104 pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
107 /* Idle states parsed correctly, initialize per-cpu pointer */
108 per_cpu(psci_power_state, cpu) = psci_states;
116 static __init int psci_cpu_init_idle(unsigned int cpu)
118 struct device_node *cpu_node;
122 * If the PSCI cpu_suspend function hook has not been initialized
123 * idle states must not be enabled, so bail out
125 if (!psci_ops.cpu_suspend)
128 cpu_node = of_cpu_device_node_get(cpu);
132 ret = psci_dt_cpu_init_idle(cpu_node, cpu);
134 of_node_put(cpu_node);
139 static int __init psci_idle_init_cpu(int cpu)
141 struct cpuidle_driver *drv;
142 struct device_node *cpu_node;
143 const char *enable_method;
146 cpu_node = of_cpu_device_node_get(cpu);
151 * Check whether the enable-method for the cpu is PSCI, fail
154 enable_method = of_get_property(cpu_node, "enable-method", NULL);
155 if (!enable_method || (strcmp(enable_method, "psci")))
158 of_node_put(cpu_node);
162 drv = kmemdup(&psci_idle_driver, sizeof(*drv), GFP_KERNEL);
166 drv->cpumask = (struct cpumask *)cpumask_of(cpu);
169 * Initialize idle states data, starting at index 1, since
170 * by default idle state 0 is the quiescent state reached
171 * by the cpu by executing the wfi instruction.
173 * If no DT idle states are detected (ret == 0) let the driver
174 * initialization fail accordingly since there is no reason to
175 * initialize the idle driver if only wfi is supported, the
176 * default archictectural back-end already executes wfi
179 ret = dt_init_idle_driver(drv, psci_idle_state_match, 1);
181 ret = ret ? : -ENODEV;
186 * Initialize PSCI idle states.
188 ret = psci_cpu_init_idle(cpu);
190 pr_err("CPU %d failed to PSCI idle\n", cpu);
194 ret = cpuidle_register(drv, NULL);
206 * psci_idle_init - Initializes PSCI cpuidle driver
208 * Initializes PSCI cpuidle driver for all CPUs, if any CPU fails
209 * to register cpuidle driver then rollback to cancel all CPUs
212 static int __init psci_idle_init(void)
215 struct cpuidle_driver *drv;
216 struct cpuidle_device *dev;
218 for_each_possible_cpu(cpu) {
219 ret = psci_idle_init_cpu(cpu);
228 dev = per_cpu(cpuidle_devices, cpu);
229 drv = cpuidle_get_cpu_driver(dev);
230 cpuidle_unregister(drv);
236 device_initcall(psci_idle_init);