150 lines
4.0 KiB
C
150 lines
4.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright 2012 Linaro Ltd.
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*/
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#include <linux/cpuidle.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <asm/cpuidle.h>
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extern struct of_cpuidle_method __cpuidle_method_of_table[];
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static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel
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__used __section(__cpuidle_method_of_table_end);
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static struct cpuidle_ops cpuidle_ops[NR_CPUS] __ro_after_init;
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/**
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* arm_cpuidle_simple_enter() - a wrapper to cpu_do_idle()
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* @dev: not used
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* @drv: not used
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* @index: not used
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*
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* A trivial wrapper to allow the cpu_do_idle function to be assigned as a
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* cpuidle callback by matching the function signature.
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*
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* Returns the index passed as parameter
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*/
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int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
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struct cpuidle_driver *drv, int index)
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{
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cpu_do_idle();
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return index;
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}
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/**
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* arm_cpuidle_suspend() - function to enter low power idle states
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* @index: an integer used as an identifier for the low level PM callbacks
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*
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* This function calls the underlying arch specific low level PM code as
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* registered at the init time.
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*
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* Returns the result of the suspend callback.
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*/
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int arm_cpuidle_suspend(int index)
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{
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int cpu = smp_processor_id();
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return cpuidle_ops[cpu].suspend(index);
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}
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/**
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* arm_cpuidle_get_ops() - find a registered cpuidle_ops by name
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* @method: the method name
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*
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* Search in the __cpuidle_method_of_table array the cpuidle ops matching the
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* method name.
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*
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* Returns a struct cpuidle_ops pointer, NULL if not found.
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*/
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static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
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{
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struct of_cpuidle_method *m = __cpuidle_method_of_table;
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for (; m->method; m++)
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if (!strcmp(m->method, method))
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return m->ops;
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return NULL;
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}
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/**
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* arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree
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* @dn: a pointer to a struct device node corresponding to a cpu node
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* @cpu: the cpu identifier
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*
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* Get the method name defined in the 'enable-method' property, retrieve the
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* associated cpuidle_ops and do a struct copy. This copy is needed because all
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* cpuidle_ops are tagged __initconst and will be unloaded after the init
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* process.
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*
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* Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
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* no cpuidle_ops is registered for the 'enable-method', or if either init or
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* suspend callback isn't defined.
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*/
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static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
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{
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const char *enable_method;
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const struct cpuidle_ops *ops;
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enable_method = of_get_property(dn, "enable-method", NULL);
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if (!enable_method)
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return -ENOENT;
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ops = arm_cpuidle_get_ops(enable_method);
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if (!ops) {
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pr_warn("%pOF: unsupported enable-method property: %s\n",
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dn, enable_method);
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return -EOPNOTSUPP;
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}
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if (!ops->init || !ops->suspend) {
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pr_warn("cpuidle_ops '%s': no init or suspend callback\n",
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enable_method);
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return -EOPNOTSUPP;
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}
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cpuidle_ops[cpu] = *ops; /* structure copy */
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pr_notice("cpuidle: enable-method property '%s'"
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" found operations\n", enable_method);
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return 0;
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}
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/**
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* arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu
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* @cpu: the cpu to be initialized
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*
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* Initialize the cpuidle ops with the device for the cpu and then call
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* the cpu's idle initialization callback. This may fail if the underlying HW
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* is not operational.
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*
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* Returns:
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* 0 on success,
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* -ENODEV if it fails to find the cpu node in the device tree,
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* -EOPNOTSUPP if it does not find a registered and valid cpuidle_ops for
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* this cpu,
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* -ENOENT if it fails to find an 'enable-method' property,
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* -ENXIO if the HW reports a failure or a misconfiguration,
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* -ENOMEM if the HW report an memory allocation failure
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*/
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int __init arm_cpuidle_init(int cpu)
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{
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struct device_node *cpu_node = of_cpu_device_node_get(cpu);
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int ret;
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if (!cpu_node)
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return -ENODEV;
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ret = arm_cpuidle_read_ops(cpu_node, cpu);
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if (!ret)
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ret = cpuidle_ops[cpu].init(cpu_node, cpu);
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of_node_put(cpu_node);
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return ret;
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}
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