cpuquiet: driver support

Change-Id: I4f3f67d4459eeda519efdfd80e1283bef2d597e3
Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Reviewed-on: http://git-master/r/105266
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Tested-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Reviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>

Rebase-Id: R23fdadebbf0644ed585f4d4d5ff8dad556773d2a

drivers/cpuquiet/driver.c

@@ -0,0 +1,200 @@
+/*
+ * 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 <linux/cpu.h>
+#include <linux/jiffies.h>
+#include <linux/slab.h>
+#include <asm/cputime.h>
+
+#include "cpuquiet.h"
+
+struct cpuquiet_cpu_stat {
+	cputime64_t time_up_total;
+	u64 last_update;
+	unsigned int up_down_count;
+	struct kobject cpu_kobject;
+};
+
+struct cpu_attribute {
+	struct attribute attr;
+	enum { up_down_count, time_up_total } type;
+};
+
+static struct cpuquiet_driver *cpuquiet_curr_driver;
+struct cpuquiet_cpu_stat *stats;
+
+#define CPU_ATTRIBUTE(_name) \
+	static struct cpu_attribute _name ## _attr = {			\
+		.attr =  {.name = __stringify(_name), .mode = 0444 },	\
+		.type	= _name,					\
+}
+
+CPU_ATTRIBUTE(up_down_count);
+CPU_ATTRIBUTE(time_up_total);
+
+static struct attribute *cpu_attributes[] = {
+	&up_down_count_attr.attr,
+	&time_up_total_attr.attr,
+	NULL,
+};
+
+static void stats_update(struct cpuquiet_cpu_stat *stat, bool up)
+{
+	u64 cur_jiffies = get_jiffies_64();
+	bool was_up = stat->up_down_count & 0x1;
+
+	if (was_up)
+		stat->time_up_total = cputime64_add(stat->time_up_total,
+			cputime64_sub(cur_jiffies, stat->last_update));
+
+	if (was_up != up)
+		stat->up_down_count++;
+
+	stat->last_update = cur_jiffies;
+}
+
+int cpuquiet_quiesence_cpu(unsigned int cpunumber)
+{
+	int err = -EPERM;
+
+	if (cpuquiet_curr_driver && cpuquiet_curr_driver->quiesence_cpu)
+		err = cpuquiet_curr_driver->quiesence_cpu(cpunumber);
+
+	stats_update(stats + cpunumber, 0);
+
+	return err;
+}
+EXPORT_SYMBOL(cpuquiet_quiesence_cpu);
+
+int cpuquiet_wake_cpu(unsigned int cpunumber)
+{
+	int err = -EPERM;
+
+	if (cpuquiet_curr_driver && cpuquiet_curr_driver->wake_cpu)
+		err = cpuquiet_curr_driver->wake_cpu(cpunumber);
+
+	stats_update(stats + cpunumber, 1);
+
+	return err;
+}
+EXPORT_SYMBOL(cpuquiet_wake_cpu);
+
+static ssize_t stats_sysfs_show(struct kobject *kobj,
+			struct attribute *attr, char *buf)
+{
+	struct cpu_attribute *cattr =
+		container_of(attr, struct cpu_attribute, attr);
+	struct cpuquiet_cpu_stat *stat  =
+		container_of(kobj, struct cpuquiet_cpu_stat, cpu_kobject);
+	ssize_t len = 0;
+	bool was_up = stat->up_down_count & 0x1;
+
+	stats_update(stat, was_up);
+
+	switch (cattr->type) {
+	case up_down_count:
+		len = sprintf(buf, "%u\n", stat->up_down_count);
+		break;
+	case time_up_total:
+		len =  sprintf(buf, "%llu\n", stat->time_up_total);
+		break;
+	}
+
+	return len;
+}
+
+static const struct sysfs_ops stats_sysfs_ops = {
+	.show = stats_sysfs_show,
+};
+
+static struct kobj_type ktype_cpu_stats = {
+	.sysfs_ops = &stats_sysfs_ops,
+	.default_attrs = cpu_attributes,
+};
+
+int cpuquiet_register_driver(struct cpuquiet_driver *drv)
+{
+	int err = -EBUSY;
+	unsigned int cpu;
+	struct sys_device *sys_dev;
+	u64 cur_jiffies;
+
+	if (!drv)
+		return -EINVAL;
+
+	stats = kzalloc(nr_cpu_ids * sizeof(*stats), GFP_KERNEL);
+	if (!stats)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		cur_jiffies = get_jiffies_64();
+		stats[cpu].last_update = cur_jiffies;
+		if (cpu_online(cpu))
+			stats[cpu].up_down_count = 1;
+		sys_dev = get_cpu_sysdev(cpu);
+		if (sys_dev) {
+			cpuquiet_add_dev(sys_dev, cpu);
+			cpuquiet_cpu_kobject_init(&stats[cpu].cpu_kobject,
+					&ktype_cpu_stats, "stats", cpu);
+		}
+	}
+
+	mutex_lock(&cpuquiet_lock);
+	if (!cpuquiet_curr_driver) {
+		err = 0;
+		cpuquiet_curr_driver = drv;
+		cpuquiet_switch_governor(cpuquiet_get_first_governor());
+	}
+	mutex_unlock(&cpuquiet_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(cpuquiet_register_driver);
+
+struct cpuquiet_driver *cpuquiet_get_driver(void)
+{
+	return cpuquiet_curr_driver;
+}
+
+void cpuquiet_unregister_driver(struct cpuquiet_driver *drv)
+{
+	unsigned int cpu;
+
+	if (drv != cpuquiet_curr_driver) {
+		WARN(1, "invalid cpuquiet_unregister_driver(%s)\n",
+			drv->name);
+		return;
+	}
+
+	/* stop current governor first */
+	cpuquiet_switch_governor(NULL);
+
+	mutex_lock(&cpuquiet_lock);
+	cpuquiet_curr_driver = NULL;
+
+	for_each_possible_cpu(cpu) {
+		kobject_put(&stats[cpu].cpu_kobject);
+		cpuquiet_remove_dev(cpu);
+	}
+
+	mutex_unlock(&cpuquiet_lock);
+}
+EXPORT_SYMBOL(cpuquiet_unregister_driver);