1 files changed, 149 insertions, 0 deletions
diff --git a/arch/arm/kernel/cpuidle.c b/arch/arm/kernel/cpuidle.c
new file mode 100644
index 000000000..e1684623e
--- /dev/null
+++ b/arch/arm/kernel/cpuidle.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2012 Linaro Ltd.
+ */
+
+#include <linux/cpuidle.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <asm/cpuidle.h>
+
+extern struct of_cpuidle_method __cpuidle_method_of_table[];
+
+static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel
+	__used __section("__cpuidle_method_of_table_end");
+
+static struct cpuidle_ops cpuidle_ops[NR_CPUS] __ro_after_init;
+
+/**
+ * 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)
+{
+	cpu_do_idle();
+
+	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 the result of the suspend callback.
+ */
+int arm_cpuidle_suspend(int index)
+{
+	int cpu = smp_processor_id();
+
+	return cpuidle_ops[cpu].suspend(index);
+}
+
+/**
+ * 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 const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
+{
+	struct of_cpuidle_method *m = __cpuidle_method_of_table;
+
+	for (; m->method; m++)
+		if (!strcmp(m->method, method))
+			return m->ops;
+
+	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 __initconst 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', or if either init or
+ * suspend callback isn't defined.
+ */
+static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
+{
+	const char *enable_method;
+	const struct cpuidle_ops *ops;
+
+	enable_method = of_get_property(dn, "enable-method", NULL);
+	if (!enable_method)
+		return -ENOENT;
+
+	ops = arm_cpuidle_get_ops(enable_method);
+	if (!ops) {
+		pr_warn("%pOF: unsupported enable-method property: %s\n",
+			dn, enable_method);
+		return -EOPNOTSUPP;
+	}
+
+	if (!ops->init || !ops->suspend) {
+		pr_warn("cpuidle_ops '%s': no init or suspend callback\n",
+			enable_method);
+		return -EOPNOTSUPP;
+	}
+
+	cpuidle_ops[cpu] = *ops; /* structure copy */
+
+	pr_notice("cpuidle: enable-method property '%s'"
+		  " found operations\n", enable_method);
+
+	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 and valid 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);
+	int ret;
+
+	if (!cpu_node)
+		return -ENODEV;
+
+	ret = arm_cpuidle_read_ops(cpu_node, cpu);
+	if (!ret)
+		ret = cpuidle_ops[cpu].init(cpu_node, cpu);
+
+	of_node_put(cpu_node);
+
+	return ret;
+}