1 /* 2 * Copyright 2012 Linaro Ltd. 3 * 4 * The code contained herein is licensed under the GNU General Public 5 * License. You may obtain a copy of the GNU General Public License 6 * Version 2 or later at the following locations: 7 * 8 * http://www.opensource.org/licenses/gpl-license.html 9 * http://www.gnu.org/copyleft/gpl.html 10 */ 11 12 #include <linux/cpuidle.h> 13 #include <linux/of.h> 14 #include <linux/of_device.h> 15 #include <asm/cpuidle.h> 16 17 extern struct of_cpuidle_method __cpuidle_method_of_table[]; 18 19 static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel 20 __used __section(__cpuidle_method_of_table_end); 21 22 static struct cpuidle_ops cpuidle_ops[NR_CPUS] __ro_after_init; 23 24 /** 25 * arm_cpuidle_simple_enter() - a wrapper to cpu_do_idle() 26 * @dev: not used 27 * @drv: not used 28 * @index: not used 29 * 30 * A trivial wrapper to allow the cpu_do_idle function to be assigned as a 31 * cpuidle callback by matching the function signature. 32 * 33 * Returns the index passed as parameter 34 */ 35 int arm_cpuidle_simple_enter(struct cpuidle_device *dev, 36 struct cpuidle_driver *drv, int index) 37 { 38 cpu_do_idle(); 39 40 return index; 41 } 42 43 /** 44 * arm_cpuidle_suspend() - function to enter low power idle states 45 * @index: an integer used as an identifier for the low level PM callbacks 46 * 47 * This function calls the underlying arch specific low level PM code as 48 * registered at the init time. 49 * 50 * Returns the result of the suspend callback. 51 */ 52 int arm_cpuidle_suspend(int index) 53 { 54 int cpu = smp_processor_id(); 55 56 return cpuidle_ops[cpu].suspend(index); 57 } 58 59 /** 60 * arm_cpuidle_get_ops() - find a registered cpuidle_ops by name 61 * @method: the method name 62 * 63 * Search in the __cpuidle_method_of_table array the cpuidle ops matching the 64 * method name. 65 * 66 * Returns a struct cpuidle_ops pointer, NULL if not found. 67 */ 68 static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method) 69 { 70 struct of_cpuidle_method *m = __cpuidle_method_of_table; 71 72 for (; m->method; m++) 73 if (!strcmp(m->method, method)) 74 return m->ops; 75 76 return NULL; 77 } 78 79 /** 80 * arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree 81 * @dn: a pointer to a struct device node corresponding to a cpu node 82 * @cpu: the cpu identifier 83 * 84 * Get the method name defined in the 'enable-method' property, retrieve the 85 * associated cpuidle_ops and do a struct copy. This copy is needed because all 86 * cpuidle_ops are tagged __initconst and will be unloaded after the init 87 * process. 88 * 89 * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if 90 * no cpuidle_ops is registered for the 'enable-method', or if either init or 91 * suspend callback isn't defined. 92 */ 93 static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu) 94 { 95 const char *enable_method; 96 const struct cpuidle_ops *ops; 97 98 enable_method = of_get_property(dn, "enable-method", NULL); 99 if (!enable_method) 100 return -ENOENT; 101 102 ops = arm_cpuidle_get_ops(enable_method); 103 if (!ops) { 104 pr_warn("%s: unsupported enable-method property: %s\n", 105 dn->full_name, enable_method); 106 return -EOPNOTSUPP; 107 } 108 109 if (!ops->init || !ops->suspend) { 110 pr_warn("cpuidle_ops '%s': no init or suspend callback\n", 111 enable_method); 112 return -EOPNOTSUPP; 113 } 114 115 cpuidle_ops[cpu] = *ops; /* structure copy */ 116 117 pr_notice("cpuidle: enable-method property '%s'" 118 " found operations\n", enable_method); 119 120 return 0; 121 } 122 123 /** 124 * arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu 125 * @cpu: the cpu to be initialized 126 * 127 * Initialize the cpuidle ops with the device for the cpu and then call 128 * the cpu's idle initialization callback. This may fail if the underlying HW 129 * is not operational. 130 * 131 * Returns: 132 * 0 on success, 133 * -ENODEV if it fails to find the cpu node in the device tree, 134 * -EOPNOTSUPP if it does not find a registered and valid cpuidle_ops for 135 * this cpu, 136 * -ENOENT if it fails to find an 'enable-method' property, 137 * -ENXIO if the HW reports a failure or a misconfiguration, 138 * -ENOMEM if the HW report an memory allocation failure 139 */ 140 int __init arm_cpuidle_init(int cpu) 141 { 142 struct device_node *cpu_node = of_cpu_device_node_get(cpu); 143 int ret; 144 145 if (!cpu_node) 146 return -ENODEV; 147 148 ret = arm_cpuidle_read_ops(cpu_node, cpu); 149 if (!ret) 150 ret = cpuidle_ops[cpu].init(cpu_node, cpu); 151 152 of_node_put(cpu_node); 153 154 return ret; 155 } 156