ARM: cpuidle: Document the code (9a309d6f) · Commits · e / devices / android_kernel_oneplus_sm7250

arch/arm/kernel/cpuidle.c

+59 −0

Original line number	Diff line number	Diff line
		@@ -21,6 +21,17 @@ static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel

		static struct cpuidle_ops cpuidle_ops[NR_CPUS];

		/**
		* arm_cpuidle_simple_enter() - a wrapper to cpu_do_idle()
		* @dev: not used
		* @drv: not used
		* @index: not used
		*
		* A trivial wrapper to allow the cpu_do_idle function to be assigned as a
		* cpuidle callback by matching the function signature.
		*
		* Returns the index passed as parameter
		*/
		int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
		struct cpuidle_driver *drv, int index)
		{
		@@ -29,6 +40,16 @@ int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
		return index;
		}

		/**
		* arm_cpuidle_suspend() - function to enter low power idle states
		* @index: an integer used as an identifier for the low level PM callbacks
		*
		* This function calls the underlying arch specific low level PM code as
		* registered at the init time.
		*
		* Returns -EOPNOTSUPP if no suspend callback is defined, the result of the
		* callback otherwise.
		*/
		int arm_cpuidle_suspend(int index)
		{
		int ret = -EOPNOTSUPP;
		@@ -40,6 +61,15 @@ int arm_cpuidle_suspend(int index)
		return ret;
		}

		/**
		* arm_cpuidle_get_ops() - find a registered cpuidle_ops by name
		* @method: the method name
		*
		* Search in the __cpuidle_method_of_table array the cpuidle ops matching the
		* method name.
		*
		* Returns a struct cpuidle_ops pointer, NULL if not found.
		*/
		static struct cpuidle_ops __init arm_cpuidle_get_ops(const char method)
		{
		struct of_cpuidle_method *m = __cpuidle_method_of_table;
		@@ -51,6 +81,19 @@ static struct cpuidle_ops __init arm_cpuidle_get_ops(const char method)
		return NULL;
		}

		/**
		* arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree
		* @dn: a pointer to a struct device node corresponding to a cpu node
		* @cpu: the cpu identifier
		*
		* Get the method name defined in the 'enable-method' property, retrieve the
		* associated cpuidle_ops and do a struct copy. This copy is needed because all
		* cpuidle_ops are tagged __initdata and will be unloaded after the init
		* process.
		*
		* Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
		* no cpuidle_ops is registered for the 'enable-method'.
		*/
		static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
		{
		const char *enable_method;
		@@ -75,6 +118,22 @@ static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
		return 0;
		}

		/**
		* arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu
		* @cpu: the cpu to be initialized
		*
		* Initialize the cpuidle ops with the device for the cpu and then call
		* the cpu's idle initialization callback. This may fail if the underlying HW
		* is not operational.
		*
		* Returns:
		* 0 on success,
		* -ENODEV if it fails to find the cpu node in the device tree,
		* -EOPNOTSUPP if it does not find a registered cpuidle_ops for this cpu,
		* -ENOENT if it fails to find an 'enable-method' property,
		* -ENXIO if the HW reports a failure or a misconfiguration,
		* -ENOMEM if the HW report an memory allocation failure
		*/
		int __init arm_cpuidle_init(int cpu)
		{
		struct device_node *cpu_node = of_cpu_device_node_get(cpu);