Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / arch / arm / kernel / cpuidle.c

diff --git a/kernel/arch/arm/kernel/cpuidle.c b/kernel/arch/arm/kernel/cpuidle.c
new file mode 100644 (file)
index 0000000..318da33
--- /dev/null
+++ b/kernel/arch/arm/kernel/cpuidle.c
@@ -0,0 +1,152 @@
+/*
+ * Copyright 2012 Linaro Ltd.
+ *
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+#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];
+
+/**
+ * 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 -EOPNOTSUPP if no suspend callback is defined, the result of the
+ * callback otherwise.
+ */
+int arm_cpuidle_suspend(int index)
+{
+       int ret = -EOPNOTSUPP;
+       int cpu = smp_processor_id();
+
+       if (cpuidle_ops[cpu].suspend)
+               ret = cpuidle_ops[cpu].suspend(cpu, 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;
+
+       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 __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;
+       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("%s: unsupported enable-method property: %s\n",
+                       dn->full_name, 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 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 && cpuidle_ops[cpu].init)
+               ret = cpuidle_ops[cpu].init(cpu_node, cpu);
+
+       of_node_put(cpu_node);
+
+       return ret;
+}