1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright 2012 Linaro Ltd. 4 */ 5 6 #include <linux/cpuidle.h> 7 #include <linux/of.h> 8 #include <asm/cpuidle.h> 9 10 extern struct of_cpuidle_method __cpuidle_method_of_table[]; 11 12 static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel 13 __used __section("__cpuidle_method_of_table_end"); 14 15 static struct cpuidle_ops cpuidle_ops[NR_CPUS] __ro_after_init; 16 17 /** 18 * arm_cpuidle_simple_enter() - a wrapper to cpu_do_idle() 19 * @dev: not used 20 * @drv: not used 21 * @index: not used 22 * 23 * A trivial wrapper to allow the cpu_do_idle function to be assigned as a 24 * cpuidle callback by matching the function signature. 25 * 26 * Returns the index passed as parameter 27 */ 28 __cpuidle int arm_cpuidle_simple_enter(struct cpuidle_device *dev, struct 29 cpuidle_driver *drv, int index) 30 { 31 cpu_do_idle(); 32 33 return index; 34 } 35 36 /** 37 * arm_cpuidle_suspend() - function to enter low power idle states 38 * @index: an integer used as an identifier for the low level PM callbacks 39 * 40 * This function calls the underlying arch specific low level PM code as 41 * registered at the init time. 42 * 43 * Returns the result of the suspend callback. 44 */ 45 int arm_cpuidle_suspend(int index) 46 { 47 int cpu = smp_processor_id(); 48 49 return cpuidle_ops[cpu].suspend(index); 50 } 51 52 /** 53 * arm_cpuidle_get_ops() - find a registered cpuidle_ops by name 54 * @method: the method name 55 * 56 * Search in the __cpuidle_method_of_table array the cpuidle ops matching the 57 * method name. 58 * 59 * Returns a struct cpuidle_ops pointer, NULL if not found. 60 */ 61 static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method) 62 { 63 struct of_cpuidle_method *m = __cpuidle_method_of_table; 64 65 for (; m->method; m++) 66 if (!strcmp(m->method, method)) 67 return m->ops; 68 69 return NULL; 70 } 71 72 /** 73 * arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree 74 * @dn: a pointer to a struct device node corresponding to a cpu node 75 * @cpu: the cpu identifier 76 * 77 * Get the method name defined in the 'enable-method' property, retrieve the 78 * associated cpuidle_ops and do a struct copy. This copy is needed because all 79 * cpuidle_ops are tagged __initconst and will be unloaded after the init 80 * process. 81 * 82 * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if 83 * no cpuidle_ops is registered for the 'enable-method', or if either init or 84 * suspend callback isn't defined. 85 */ 86 static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu) 87 { 88 const char *enable_method; 89 const struct cpuidle_ops *ops; 90 91 enable_method = of_get_property(dn, "enable-method", NULL); 92 if (!enable_method) 93 return -ENOENT; 94 95 ops = arm_cpuidle_get_ops(enable_method); 96 if (!ops) { 97 pr_warn("%pOF: unsupported enable-method property: %s\n", 98 dn, enable_method); 99 return -EOPNOTSUPP; 100 } 101 102 if (!ops->init || !ops->suspend) { 103 pr_warn("cpuidle_ops '%s': no init or suspend callback\n", 104 enable_method); 105 return -EOPNOTSUPP; 106 } 107 108 cpuidle_ops[cpu] = *ops; /* structure copy */ 109 110 pr_notice("cpuidle: enable-method property '%s'" 111 " found operations\n", enable_method); 112 113 return 0; 114 } 115 116 /** 117 * arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu 118 * @cpu: the cpu to be initialized 119 * 120 * Initialize the cpuidle ops with the device for the cpu and then call 121 * the cpu's idle initialization callback. This may fail if the underlying HW 122 * is not operational. 123 * 124 * Returns: 125 * 0 on success, 126 * -ENODEV if it fails to find the cpu node in the device tree, 127 * -EOPNOTSUPP if it does not find a registered and valid cpuidle_ops for 128 * this cpu, 129 * -ENOENT if it fails to find an 'enable-method' property, 130 * -ENXIO if the HW reports a failure or a misconfiguration, 131 * -ENOMEM if the HW report an memory allocation failure 132 */ 133 int __init arm_cpuidle_init(int cpu) 134 { 135 struct device_node *cpu_node = of_cpu_device_node_get(cpu); 136 int ret; 137 138 if (!cpu_node) 139 return -ENODEV; 140 141 ret = arm_cpuidle_read_ops(cpu_node, cpu); 142 if (!ret) 143 ret = cpuidle_ops[cpu].init(cpu_node, cpu); 144 145 of_node_put(cpu_node); 146 147 return ret; 148 } 149