cpufreq: Add simple userspace CPU-boost driver

This is a simple CPU-boost driver designed to be controlled by the power HAL's power hints.

Usage: When 1 is written to /sys/module/userspace_cpu_boost/parameters/boost_now by the power HAL, all online CPUs are boosted to a specified boost frequency for a specified duration of time. The default boost frequency is 1134MHz and the default boost duration is 3 seconds.

This is meant to be an open-source solution for the closed-source CPU-boosting behavior that is present on stock AOSP for the Nexus 5.

Signed-off-by: Sultanxda <sultanxda@gmail.com>

Author: kerneltoast

drivers/cpufreq/Kconfig

@@ -217,5 +217,10 @@ depends on X86
 source "drivers/cpufreq/Kconfig.x86"
 endmenu
 
+config USERSPACE_CPU_BOOST
+	bool "Userspace-controlled CPU boosting"
+	help
+	  Simple CPU-boost driver that is controlled by userspace.
+
 endif
 endmenu

drivers/cpufreq/Makefile

@@ -1,5 +1,6 @@
 # CPUfreq core
 obj-$(CONFIG_CPU_FREQ)			+= cpufreq.o
+obj-$(CONFIG_USERSPACE_CPU_BOOST)	+= userspace_cpu-boost.o
 # CPUfreq stats
 obj-$(CONFIG_CPU_FREQ_STAT)             += cpufreq_stats.o
 

drivers/cpufreq/userspace_cpu-boost.c

@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2014, Sultanxda <sultanxda@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+/* CPU boost freq in KHz. All online CPUs
+ * are boosted. */
+static int boost_freq_khz = 1134000;
+module_param(boost_freq_khz, int, 0644);
+
+/* Duration to boost CPUs in millisecs. */
+static int boost_duration_ms = 3000;
+module_param(boost_duration_ms, int, 0644);
+
+/* File for userspace to write to in
+ * order to request boost. */
+static int boost_now = 0;
+module_param(boost_now, int, 0644);
+
+/* Time in ms to poll for boost request from
+ * userspace. */
+#define BOOST_CHECK_MS 20
+
+/* CPU's default minfreq in KHz. */
+#define DEFAULT_MINFREQ_KHZ 192000
+
+static struct delayed_work check_input_boost;
+
+static void input_boost_main(struct work_struct *work)
+{
+	struct cpufreq_policy *cpu_policy = NULL;
+	static int cpu_boosted = 0;
+	unsigned int minfreq = DEFAULT_MINFREQ_KHZ;
+	unsigned int wait_ms = BOOST_CHECK_MS;
+	int cpu = 0;
+
+	if (cpu_boosted) {
+		/* restore original minfreq */
+		get_online_cpus();
+		for_each_online_cpu(cpu) {
+			cpu_policy = cpufreq_cpu_get(cpu);
+			cpufreq_verify_within_limits(cpu_policy, minfreq, UINT_MAX);
+			cpu_policy->user_policy.min = minfreq;
+			cpufreq_update_policy(cpu);
+			cpufreq_cpu_put(cpu_policy);
+		}
+		put_online_cpus();
+		cpu_boosted = 0;
+		wait_ms = 0;
+		boost_now = 0;
+		goto end;
+	}
+
+	if (boost_now) {
+		minfreq =  boost_freq_khz;
+
+		/* boost online CPUs */
+		get_online_cpus();
+		for_each_online_cpu(cpu) {
+			cpu_policy = cpufreq_cpu_get(cpu);
+			cpufreq_verify_within_limits(cpu_policy, minfreq, UINT_MAX);
+			cpu_policy->user_policy.min = minfreq;
+			cpufreq_update_policy(cpu);
+			cpufreq_cpu_put(cpu_policy);
+		}
+		put_online_cpus();
+		cpu_boosted = 1;
+		wait_ms = boost_duration_ms;
+	}
+
+end:
+	schedule_delayed_work(&check_input_boost,
+				msecs_to_jiffies(wait_ms));
+}
+
+static int userspace_boost_init(void)
+{
+	INIT_DELAYED_WORK(&check_input_boost, input_boost_main);
+	schedule_delayed_work(&check_input_boost, 0);
+
+	return 0;
+}
+late_initcall(userspace_boost_init);
+
+MODULE_AUTHOR("Sultanxda <sultanxda@gmail.com>");
+MODULE_DESCRIPTION("Userspace CPU-Boost Driver");
+MODULE_LICENSE("GPLv2");