cpuquiet: governor support

Change-Id: I05b9dedc04bb3b2ddba6202a002c1e5514ec4777
Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Reviewed-on: http://git-master/r/105269
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Tested-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Reviewed-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Reviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>

Rebase-Id: R481f3df7610b737f6c054370efbe3bdb95a5e78d

drivers/cpuquiet/governor.c

@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2012 NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ */
+
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/cpuquiet.h>
+
+#include "cpuquiet.h"
+
+LIST_HEAD(cpuquiet_governors);
+struct cpuquiet_governor *cpuquiet_curr_governor;
+
+struct cpuquiet_governor *cpuquiet_get_first_governor(void)
+{
+	if (!list_empty(&cpuquiet_governors))
+		return list_entry(&cpuquiet_governors, struct cpuquiet_governor,
+					governor_list);
+	else
+		return NULL;
+}
+
+struct cpuquiet_governor *cpuquiet_find_governor(const char *str)
+{
+	struct cpuquiet_governor *gov;
+
+	list_for_each_entry(gov, &cpuquiet_governors, governor_list)
+		if (!strnicmp(str, gov->name, CPUQUIET_NAME_LEN))
+			return gov;
+
+	return NULL;
+}
+
+int cpuquiet_switch_governor(struct cpuquiet_governor *gov)
+{
+	int err = 0;
+
+	if (cpuquiet_curr_governor) {
+		if (cpuquiet_curr_governor->stop)
+			cpuquiet_curr_governor->stop();
+		module_put(cpuquiet_curr_governor->owner);
+	}
+
+	cpuquiet_curr_governor = gov;
+
+	if (gov) {
+		if (!try_module_get(cpuquiet_curr_governor->owner))
+			return -EINVAL;
+		if (gov->start)
+			err = gov->start();
+		if (!err)
+			cpuquiet_curr_governor = gov;
+	}
+
+	return err;
+}
+
+int cpuquiet_register_governor(struct cpuquiet_governor *gov)
+{
+	int ret = -EEXIST;
+
+	if (!gov)
+		return -EINVAL;
+
+	mutex_lock(&cpuquiet_lock);
+	if (cpuquiet_find_governor(gov->name) == NULL) {
+		ret = 0;
+		list_add_tail(&gov->governor_list, &cpuquiet_governors);
+		if (!cpuquiet_curr_governor && cpuquiet_get_driver())
+			cpuquiet_switch_governor(gov);
+	}
+	mutex_unlock(&cpuquiet_lock);
+
+	return ret;
+}
+
+void cpuquiet_unregister_governor(struct cpuquiet_governor *gov)
+{
+	if (!gov)
+		return;
+
+	mutex_lock(&cpuquiet_lock);
+	if (cpuquiet_curr_governor == gov)
+		cpuquiet_switch_governor(NULL);
+	list_del(&gov->governor_list);
+	mutex_unlock(&cpuquiet_lock);
+}