1 files changed, 141 insertions, 0 deletions

diff --git a/drivers/cpuidle/governor.c b/drivers/cpuidle/governor.c
new file mode 100644
index 000000000000..bb699cb2dc5a
--- /dev/null
+++ b/drivers/cpuidle/governor.c
@@ -0,0 +1,141 @@
+/*
+ * governor.c - governor support
+ *
+ * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
+ *               Shaohua Li <shaohua.li@intel.com>
+ *               Adam Belay <abelay@novell.com>
+ *
+ * This code is licenced under the GPL.
+ */
+
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/cpuidle.h>
+
+#include "cpuidle.h"
+
+LIST_HEAD(cpuidle_governors);
+struct cpuidle_governor *cpuidle_curr_governor;
+
+/**
+ * __cpuidle_find_governor - finds a governor of the specified name
+ * @str: the name
+ *
+ * Must be called with cpuidle_lock aquired.
+ */
+static struct cpuidle_governor * __cpuidle_find_governor(const char *str)
+{
+        struct cpuidle_governor *gov;
+
+        list_for_each_entry(gov, &cpuidle_governors, governor_list)
+                if (!strnicmp(str, gov->name, CPUIDLE_NAME_LEN))
+                        return gov;
+
+        return NULL;
+}
+
+/**
+ * cpuidle_switch_governor - changes the governor
+ * @gov: the new target governor
+ *
+ * NOTE: "gov" can be NULL to specify disabled
+ * Must be called with cpuidle_lock aquired.
+ */
+int cpuidle_switch_governor(struct cpuidle_governor *gov)
+{
+        struct cpuidle_device *dev;
+
+        if (gov == cpuidle_curr_governor)
+                return 0;
+
+        cpuidle_uninstall_idle_handler();
+
+        if (cpuidle_curr_governor) {
+                list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
+                        cpuidle_disable_device(dev);
+                module_put(cpuidle_curr_governor->owner);
+        }
+
+        cpuidle_curr_governor = gov;
+
+        if (gov) {
+                if (!try_module_get(cpuidle_curr_governor->owner))
+                        return -EINVAL;
+                list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
+                        cpuidle_enable_device(dev);
+                cpuidle_install_idle_handler();
+                printk(KERN_INFO "cpuidle: using governor %s\n", gov->name);
+        }
+
+        return 0;
+}
+
+/**
+ * cpuidle_register_governor - registers a governor
+ * @gov: the governor
+ */
+int cpuidle_register_governor(struct cpuidle_governor *gov)
+{
+        int ret = -EEXIST;
+
+        if (!gov || !gov->select)
+                return -EINVAL;
+
+        mutex_lock(&cpuidle_lock);
+        if (__cpuidle_find_governor(gov->name) == NULL) {
+                ret = 0;
+                list_add_tail(&gov->governor_list, &cpuidle_governors);
+                if (!cpuidle_curr_governor ||
+                    cpuidle_curr_governor->rating < gov->rating)
+                        cpuidle_switch_governor(gov);
+        }
+        mutex_unlock(&cpuidle_lock);
+
+        return ret;
+}
+
+EXPORT_SYMBOL_GPL(cpuidle_register_governor);
+
+/**
+ * cpuidle_replace_governor - find a replacement governor
+ * @exclude_rating: the rating that will be skipped while looking for
+ * new governor.
+ */
+static struct cpuidle_governor *cpuidle_replace_governor(int exclude_rating)
+{
+        struct cpuidle_governor *gov;
+        struct cpuidle_governor *ret_gov = NULL;
+        unsigned int max_rating = 0;
+
+        list_for_each_entry(gov, &cpuidle_governors, governor_list) {
+                if (gov->rating == exclude_rating)
+                        continue;
+                if (gov->rating > max_rating) {
+                        max_rating = gov->rating;
+                        ret_gov = gov;
+                }
+        }
+
+        return ret_gov;
+}
+
+/**
+ * cpuidle_unregister_governor - unregisters a governor
+ * @gov: the governor
+ */
+void cpuidle_unregister_governor(struct cpuidle_governor *gov)
+{
+        if (!gov)
+                return;
+
+        mutex_lock(&cpuidle_lock);
+        if (gov == cpuidle_curr_governor) {
+                struct cpuidle_governor *new_gov;
+                new_gov = cpuidle_replace_governor(gov->rating);
+                cpuidle_switch_governor(new_gov);
+        }
+        list_del(&gov->governor_list);
+        mutex_unlock(&cpuidle_lock);
+}
+
+EXPORT_SYMBOL_GPL(cpuidle_unregister_governor);