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]; 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 -EOPNOTSUPP if no suspend callback is defined, the result of the 51 * callback otherwise. 52 */ 53 int arm_cpuidle_suspend(int index) 54 { 55 int ret = -EOPNOTSUPP; 56 int cpu = smp_processor_id(); 57 58 if (cpuidle_ops[cpu].suspend) 59 ret = cpuidle_ops[cpu].suspend(index); 60 61 return ret; 62 } 63 64 /** 65 * arm_cpuidle_get_ops() - find a registered cpuidle_ops by name 66 * @method: the method name 67 * 68 * Search in the __cpuidle_method_of_table array the cpuidle ops matching the 69 * method name. 70 * 71 * Returns a struct cpuidle_ops pointer, NULL if not found. 72 */ 73 static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method) 74 { 75 struct of_cpuidle_method *m = __cpuidle_method_of_table; 76 77 for (; m->method; m++) 78 if (!strcmp(m->method, method)) 79 return m->ops; 80 81 return NULL; 82 } 83 84 /** 85 * arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree 86 * @dn: a pointer to a struct device node corresponding to a cpu node 87 * @cpu: the cpu identifier 88 * 89 * Get the method name defined in the 'enable-method' property, retrieve the 90 * associated cpuidle_ops and do a struct copy. This copy is needed because all 91 * cpuidle_ops are tagged __initconst and will be unloaded after the init 92 * process. 93 * 94 * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if 95 * no cpuidle_ops is registered for the 'enable-method'. 96 */ 97 static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu) 98 { 99 const char *enable_method; 100 const struct cpuidle_ops *ops; 101 102 enable_method = of_get_property(dn, "enable-method", NULL); 103 if (!enable_method) 104 return -ENOENT; 105 106 ops = arm_cpuidle_get_ops(enable_method); 107 if (!ops) { 108 pr_warn("%s: unsupported enable-method property: %s\n", 109 dn->full_name, enable_method); 110 return -EOPNOTSUPP; 111 } 112 113 cpuidle_ops[cpu] = *ops; /* structure copy */ 114 115 pr_notice("cpuidle: enable-method property '%s'" 116 " found operations\n", enable_method); 117 118 return 0; 119 } 120 121 /** 122 * arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu 123 * @cpu: the cpu to be initialized 124 * 125 * Initialize the cpuidle ops with the device for the cpu and then call 126 * the cpu's idle initialization callback. This may fail if the underlying HW 127 * is not operational. 128 * 129 * Returns: 130 * 0 on success, 131 * -ENODEV if it fails to find the cpu node in the device tree, 132 * -EOPNOTSUPP if it does not find a registered cpuidle_ops for this cpu, 133 * -ENOENT if it fails to find an 'enable-method' property, 134 * -ENXIO if the HW reports a failure or a misconfiguration, 135 * -ENOMEM if the HW report an memory allocation failure 136 */ 137 int __init arm_cpuidle_init(int cpu) 138 { 139 struct device_node *cpu_node = of_cpu_device_node_get(cpu); 140 int ret; 141 142 if (!cpu_node) 143 return -ENODEV; 144 145 ret = arm_cpuidle_read_ops(cpu_node, cpu); 146 if (!ret && cpuidle_ops[cpu].init) 147 ret = cpuidle_ops[cpu].init(cpu_node, cpu); 148 149 of_node_put(cpu_node); 150 151 return ret; 152 } 153