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 <linux/of_device.h> 9 #include <asm/cpuidle.h> 10 11 extern struct of_cpuidle_method __cpuidle_method_of_table[]; 12 13 static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel 14 __used __section("__cpuidle_method_of_table_end"); 15 16 static struct cpuidle_ops cpuidle_ops[NR_CPUS] __ro_after_init; 17 18 /** 19 * arm_cpuidle_simple_enter() - a wrapper to cpu_do_idle() 20 * @dev: not used 21 * @drv: not used 22 * @index: not used 23 * 24 * A trivial wrapper to allow the cpu_do_idle function to be assigned as a 25 * cpuidle callback by matching the function signature. 26 * 27 * Returns the index passed as parameter 28 */ 29 int arm_cpuidle_simple_enter(struct cpuidle_device *dev, 30 struct cpuidle_driver *drv, int index) 31 { 32 cpu_do_idle(); 33 34 return index; 35 } 36 37 /** 38 * arm_cpuidle_suspend() - function to enter low power idle states 39 * @index: an integer used as an identifier for the low level PM callbacks 40 * 41 * This function calls the underlying arch specific low level PM code as 42 * registered at the init time. 43 * 44 * Returns the result of the suspend callback. 45 */ 46 int arm_cpuidle_suspend(int index) 47 { 48 int cpu = smp_processor_id(); 49 50 return cpuidle_ops[cpu].suspend(index); 51 } 52 53 /** 54 * arm_cpuidle_get_ops() - find a registered cpuidle_ops by name 55 * @method: the method name 56 * 57 * Search in the __cpuidle_method_of_table array the cpuidle ops matching the 58 * method name. 59 * 60 * Returns a struct cpuidle_ops pointer, NULL if not found. 61 */ 62 static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method) 63 { 64 struct of_cpuidle_method *m = __cpuidle_method_of_table; 65 66 for (; m->method; m++) 67 if (!strcmp(m->method, method)) 68 return m->ops; 69 70 return NULL; 71 } 72 73 /** 74 * arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree 75 * @dn: a pointer to a struct device node corresponding to a cpu node 76 * @cpu: the cpu identifier 77 * 78 * Get the method name defined in the 'enable-method' property, retrieve the 79 * associated cpuidle_ops and do a struct copy. This copy is needed because all 80 * cpuidle_ops are tagged __initconst and will be unloaded after the init 81 * process. 82 * 83 * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if 84 * no cpuidle_ops is registered for the 'enable-method', or if either init or 85 * suspend callback isn't defined. 86 */ 87 static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu) 88 { 89 const char *enable_method; 90 const struct cpuidle_ops *ops; 91 92 enable_method = of_get_property(dn, "enable-method", NULL); 93 if (!enable_method) 94 return -ENOENT; 95 96 ops = arm_cpuidle_get_ops(enable_method); 97 if (!ops) { 98 pr_warn("%pOF: unsupported enable-method property: %s\n", 99 dn, enable_method); 100 return -EOPNOTSUPP; 101 } 102 103 if (!ops->init || !ops->suspend) { 104 pr_warn("cpuidle_ops '%s': no init or suspend callback\n", 105 enable_method); 106 return -EOPNOTSUPP; 107 } 108 109 cpuidle_ops[cpu] = *ops; /* structure copy */ 110 111 pr_notice("cpuidle: enable-method property '%s'" 112 " found operations\n", enable_method); 113 114 return 0; 115 } 116 117 /** 118 * arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu 119 * @cpu: the cpu to be initialized 120 * 121 * Initialize the cpuidle ops with the device for the cpu and then call 122 * the cpu's idle initialization callback. This may fail if the underlying HW 123 * is not operational. 124 * 125 * Returns: 126 * 0 on success, 127 * -ENODEV if it fails to find the cpu node in the device tree, 128 * -EOPNOTSUPP if it does not find a registered and valid cpuidle_ops for 129 * this cpu, 130 * -ENOENT if it fails to find an 'enable-method' property, 131 * -ENXIO if the HW reports a failure or a misconfiguration, 132 * -ENOMEM if the HW report an memory allocation failure 133 */ 134 int __init arm_cpuidle_init(int cpu) 135 { 136 struct device_node *cpu_node = of_cpu_device_node_get(cpu); 137 int ret; 138 139 if (!cpu_node) 140 return -ENODEV; 141 142 ret = arm_cpuidle_read_ops(cpu_node, cpu); 143 if (!ret) 144 ret = cpuidle_ops[cpu].init(cpu_node, cpu); 145 146 of_node_put(cpu_node); 147 148 return ret; 149 } 150