[linux-block.git] / drivers / cpufreq / cpufreq_userspace.c


/*
 *  linux/drivers/cpufreq/cpufreq_userspace.c
 *
 *  Copyright (C)  2001 Russell King
 *            (C)  2002 - 2004 Dominik Brodowski <linux@brodo.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/cpufreq.h>
#include <linux/cpu.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/mutex.h>

#include <asm/uaccess.h>


/**
 * A few values needed by the userspace governor
 */
static unsigned int	cpu_max_freq[NR_CPUS];
static unsigned int	cpu_min_freq[NR_CPUS];
static unsigned int	cpu_cur_freq[NR_CPUS]; /* current CPU freq */
static unsigned int	cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
static unsigned int	cpu_is_managed[NR_CPUS];

static DEFINE_MUTEX	(userspace_mutex);
static int cpus_using_userspace_governor;

#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)

/* keep track of frequency transitions */
static int
userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
                       void *data)
{
        struct cpufreq_freqs *freq = data;

	if (!cpu_is_managed[freq->cpu])
		return 0;

	dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n",
			freq->cpu, freq->new);
	cpu_cur_freq[freq->cpu] = freq->new;

        return 0;
}

static struct notifier_block userspace_cpufreq_notifier_block = {
        .notifier_call  = userspace_cpufreq_notifier
};


/**
 * cpufreq_set - set the CPU frequency
 * @freq: target frequency in kHz
 * @cpu: CPU for which the frequency is to be set
 *
 * Sets the CPU frequency to freq.
 */
static int cpufreq_set(unsigned int freq, struct cpufreq_policy *policy)
{
	int ret = -EINVAL;

	dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);

	mutex_lock(&userspace_mutex);
	if (!cpu_is_managed[policy->cpu])
		goto err;

	cpu_set_freq[policy->cpu] = freq;

	if (freq < cpu_min_freq[policy->cpu])
		freq = cpu_min_freq[policy->cpu];
	if (freq > cpu_max_freq[policy->cpu])
		freq = cpu_max_freq[policy->cpu];

	/*
	 * We're safe from concurrent calls to ->target() here
	 * as we hold the userspace_mutex lock. If we were calling
	 * cpufreq_driver_target, a deadlock situation might occur:
	 * A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
	 * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
	 */
	ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);

 err:
	mutex_unlock(&userspace_mutex);
	return ret;
}


/************************** sysfs interface ************************/
static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
{
	return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
}

static ssize_t
store_speed (struct cpufreq_policy *policy, const char *buf, size_t count)
{
	unsigned int freq = 0;
	unsigned int ret;

	ret = sscanf (buf, "%u", &freq);
	if (ret != 1)
		return -EINVAL;

	cpufreq_set(freq, policy);

	return count;
}

static struct freq_attr freq_attr_scaling_setspeed =
{
	.attr = { .name = "scaling_setspeed", .mode = 0644 },
	.show = show_speed,
	.store = store_speed,
};

static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
				   unsigned int event)
{
	unsigned int cpu = policy->cpu;
	int rc = 0;

	switch (event) {
	case CPUFREQ_GOV_START:
		if (!cpu_online(cpu))
			return -EINVAL;
		BUG_ON(!policy->cur);
		mutex_lock(&userspace_mutex);
		rc = sysfs_create_file (&policy->kobj,
					&freq_attr_scaling_setspeed.attr);
		if (rc)
			goto start_out;

		if (cpus_using_userspace_governor == 0) {
			cpufreq_register_notifier(
					&userspace_cpufreq_notifier_block,
					CPUFREQ_TRANSITION_NOTIFIER);
		}
		cpus_using_userspace_governor++;

		cpu_is_managed[cpu] = 1;
		cpu_min_freq[cpu] = policy->min;
		cpu_max_freq[cpu] = policy->max;
		cpu_cur_freq[cpu] = policy->cur;
		cpu_set_freq[cpu] = policy->cur;
		dprintk("managing cpu %u started (%u - %u kHz, currently %u kHz)\n", cpu, cpu_min_freq[cpu], cpu_max_freq[cpu], cpu_cur_freq[cpu]);
start_out:
		mutex_unlock(&userspace_mutex);
		break;
	case CPUFREQ_GOV_STOP:
		mutex_lock(&userspace_mutex);
		cpus_using_userspace_governor--;
		if (cpus_using_userspace_governor == 0) {
			cpufreq_unregister_notifier(
					&userspace_cpufreq_notifier_block,
					CPUFREQ_TRANSITION_NOTIFIER);
		}

		cpu_is_managed[cpu] = 0;
		cpu_min_freq[cpu] = 0;
		cpu_max_freq[cpu] = 0;
		cpu_set_freq[cpu] = 0;
		sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
		dprintk("managing cpu %u stopped\n", cpu);
		mutex_unlock(&userspace_mutex);
		break;
	case CPUFREQ_GOV_LIMITS:
		mutex_lock(&userspace_mutex);
		dprintk("limit event for cpu %u: %u - %u kHz,"
			"currently %u kHz, last set to %u kHz\n",
			cpu, policy->min, policy->max,
			cpu_cur_freq[cpu], cpu_set_freq[cpu]);
		if (policy->max < cpu_set_freq[cpu]) {
			__cpufreq_driver_target(policy, policy->max,
						CPUFREQ_RELATION_H);
		}
		else if (policy->min > cpu_set_freq[cpu]) {
			__cpufreq_driver_target(policy, policy->min,
						CPUFREQ_RELATION_L);
		}
		else {
			__cpufreq_driver_target(policy, cpu_set_freq[cpu],
						CPUFREQ_RELATION_L);
		}
		cpu_min_freq[cpu] = policy->min;
		cpu_max_freq[cpu] = policy->max;
		cpu_cur_freq[cpu] = policy->cur;
		mutex_unlock(&userspace_mutex);
		break;
	}
	return rc;
}


struct cpufreq_governor cpufreq_gov_userspace = {
	.name		= "userspace",
	.governor	= cpufreq_governor_userspace,
	.owner		= THIS_MODULE,
};
EXPORT_SYMBOL(cpufreq_gov_userspace);

static int __init cpufreq_gov_userspace_init(void)
{
	return cpufreq_register_governor(&cpufreq_gov_userspace);
}


static void __exit cpufreq_gov_userspace_exit(void)
{
	cpufreq_unregister_governor(&cpufreq_gov_userspace);
}


MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
MODULE_LICENSE ("GPL");

fs_initcall(cpufreq_gov_userspace_init);
module_exit(cpufreq_gov_userspace_exit);
Commit	Line	Data
c0672860	1
1da177e4 LT	2	/*
	3	* linux/drivers/cpufreq/cpufreq_userspace.c
	4	*
	5	* Copyright (C) 2001 Russell King
	6	* (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License version 2 as
	10	* published by the Free Software Foundation.
	11	*
	12	*/
	13
1da177e4 LT	14	#include <linux/kernel.h>
	15	#include <linux/module.h>
	16	#include <linux/smp.h>
	17	#include <linux/init.h>
	18	#include <linux/spinlock.h>
	19	#include <linux/interrupt.h>
	20	#include <linux/cpufreq.h>
153d7f3f	21	#include <linux/cpu.h>
1da177e4 LT	22	#include <linux/types.h>
	23	#include <linux/fs.h>
	24	#include <linux/sysfs.h>
3fc54d37	25	#include <linux/mutex.h>
1da177e4 LT	26
	27	#include <asm/uaccess.h>
	28
	29
	30	/**
	31	* A few values needed by the userspace governor
	32	*/
	33	static unsigned int cpu_max_freq[NR_CPUS];
	34	static unsigned int cpu_min_freq[NR_CPUS];
	35	static unsigned int cpu_cur_freq[NR_CPUS]; /* current CPU freq */
	36	static unsigned int cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
	37	static unsigned int cpu_is_managed[NR_CPUS];
1da177e4	38
3fc54d37	39	static DEFINE_MUTEX (userspace_mutex);
c7f652e0	40	static int cpus_using_userspace_governor;
1da177e4 LT	41
	42	#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
	43
	44	/* keep track of frequency transitions */
32ee8c3e	45	static int
1da177e4 LT	46	userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
	47	void *data)
	48	{
	49	struct cpufreq_freqs *freq = data;
	50
c7f652e0 VP	51	if (!cpu_is_managed[freq->cpu])
	52	return 0;
	53
	54	dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n",
	55	freq->cpu, freq->new);
1da177e4 LT	56	cpu_cur_freq[freq->cpu] = freq->new;
	57
	58	return 0;
	59	}
	60
	61	static struct notifier_block userspace_cpufreq_notifier_block = {
	62	.notifier_call = userspace_cpufreq_notifier
	63	};
	64
	65
32ee8c3e	66	/**
1da177e4 LT	67	* cpufreq_set - set the CPU frequency
	68	* @freq: target frequency in kHz
	69	* @cpu: CPU for which the frequency is to be set
	70	*
	71	* Sets the CPU frequency to freq.
	72	*/
c0672860	73	static int cpufreq_set(unsigned int freq, struct cpufreq_policy *policy)
1da177e4 LT	74	{
	75	int ret = -EINVAL;
	76
c0672860	77	dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
1da177e4	78
3fc54d37	79	mutex_lock(&userspace_mutex);
c0672860	80	if (!cpu_is_managed[policy->cpu])
1da177e4 LT	81	goto err;
1da177e4 LT	82
c0672860	83	cpu_set_freq[policy->cpu] = freq;
1da177e4	84
c0672860 TR	85	if (freq < cpu_min_freq[policy->cpu])
	86	freq = cpu_min_freq[policy->cpu];
	87	if (freq > cpu_max_freq[policy->cpu])
	88	freq = cpu_max_freq[policy->cpu];
1da177e4 LT	89
	90	/*
	91	* We're safe from concurrent calls to ->target() here
3fc54d37	92	* as we hold the userspace_mutex lock. If we were calling
1da177e4	93	* cpufreq_driver_target, a deadlock situation might occur:
3fc54d37	94	* A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
3fc54d37	95	* B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
1da177e4	96	*/
c0672860	97	ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
1da177e4 LT	98
1da177e4 LT	99	err:
3fc54d37	100	mutex_unlock(&userspace_mutex);
1da177e4 LT	101	return ret;
	102	}
	103
	104
	105	/************************ sysfs interface **********************/
	106	static ssize_t show_speed (struct cpufreq_policy policy, char buf)
	107	{
	108	return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
	109	}
	110
32ee8c3e DJ	111	static ssize_t
32ee8c3e DJ	112	store_speed (struct cpufreq_policy policy, const char buf, size_t count)
1da177e4 LT	113	{
	114	unsigned int freq = 0;
	115	unsigned int ret;
	116
	117	ret = sscanf (buf, "%u", &freq);
	118	if (ret != 1)
	119	return -EINVAL;
	120
c0672860	121	cpufreq_set(freq, policy);
1da177e4 LT	122
	123	return count;
	124	}
	125
32ee8c3e	126	static struct freq_attr freq_attr_scaling_setspeed =
1da177e4	127	{
7b595756	128	.attr = { .name = "scaling_setspeed", .mode = 0644 },
1da177e4 LT	129	.show = show_speed,
	130	.store = store_speed,
	131	};
	132
	133	static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
	134	unsigned int event)
	135	{
	136	unsigned int cpu = policy->cpu;
914f7c31 JG	137	int rc = 0;
914f7c31 JG	138
1da177e4 LT	139	switch (event) {
	140	case CPUFREQ_GOV_START:
	141	if (!cpu_online(cpu))
	142	return -EINVAL;
	143	BUG_ON(!policy->cur);
3fc54d37	144	mutex_lock(&userspace_mutex);
914f7c31 JG	145	rc = sysfs_create_file (&policy->kobj,
	146	&freq_attr_scaling_setspeed.attr);
	147	if (rc)
	148	goto start_out;
	149
c7f652e0 VP	150	if (cpus_using_userspace_governor == 0) {
	151	cpufreq_register_notifier(
	152	&userspace_cpufreq_notifier_block,
	153	CPUFREQ_TRANSITION_NOTIFIER);
	154	}
	155	cpus_using_userspace_governor++;
	156
32ee8c3e	157	cpu_is_managed[cpu] = 1;
1da177e4 LT	158	cpu_min_freq[cpu] = policy->min;
	159	cpu_max_freq[cpu] = policy->max;
	160	cpu_cur_freq[cpu] = policy->cur;
	161	cpu_set_freq[cpu] = policy->cur;
1da177e4	162	dprintk("managing cpu %u started (%u - %u kHz, currently %u kHz)\n", cpu, cpu_min_freq[cpu], cpu_max_freq[cpu], cpu_cur_freq[cpu]);
914f7c31	163	start_out:
3fc54d37	164	mutex_unlock(&userspace_mutex);
1da177e4 LT	165	break;
1da177e4 LT	166	case CPUFREQ_GOV_STOP:
3fc54d37	167	mutex_lock(&userspace_mutex);
c7f652e0 VP	168	cpus_using_userspace_governor--;
	169	if (cpus_using_userspace_governor == 0) {
	170	cpufreq_unregister_notifier(
	171	&userspace_cpufreq_notifier_block,
	172	CPUFREQ_TRANSITION_NOTIFIER);
	173	}
	174
1da177e4 LT	175	cpu_is_managed[cpu] = 0;
	176	cpu_min_freq[cpu] = 0;
	177	cpu_max_freq[cpu] = 0;
	178	cpu_set_freq[cpu] = 0;
	179	sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
	180	dprintk("managing cpu %u stopped\n", cpu);
3fc54d37	181	mutex_unlock(&userspace_mutex);
1da177e4 LT	182	break;
1da177e4 LT	183	case CPUFREQ_GOV_LIMITS:
3fc54d37	184	mutex_lock(&userspace_mutex);
c0672860 TR	185	dprintk("limit event for cpu %u: %u - %u kHz,"
	186	"currently %u kHz, last set to %u kHz\n",
	187	cpu, policy->min, policy->max,
	188	cpu_cur_freq[cpu], cpu_set_freq[cpu]);
1da177e4	189	if (policy->max < cpu_set_freq[cpu]) {
c0672860 TR	190	__cpufreq_driver_target(policy, policy->max,
	191	CPUFREQ_RELATION_H);
	192	}
	193	else if (policy->min > cpu_set_freq[cpu]) {
	194	__cpufreq_driver_target(policy, policy->min,
	195	CPUFREQ_RELATION_L);
1da177e4	196	}
c0672860 TR	197	else {
	198	__cpufreq_driver_target(policy, cpu_set_freq[cpu],
	199	CPUFREQ_RELATION_L);
	200	}
	201	cpu_min_freq[cpu] = policy->min;
	202	cpu_max_freq[cpu] = policy->max;
	203	cpu_cur_freq[cpu] = policy->cur;
3fc54d37	204	mutex_unlock(&userspace_mutex);
1da177e4 LT	205	break;
1da177e4 LT	206	}
914f7c31	207	return rc;
1da177e4 LT	208	}
	209
	210
	211	struct cpufreq_governor cpufreq_gov_userspace = {
	212	.name = "userspace",
	213	.governor = cpufreq_governor_userspace,
	214	.owner = THIS_MODULE,
	215	};
	216	EXPORT_SYMBOL(cpufreq_gov_userspace);
	217
	218	static int __init cpufreq_gov_userspace_init(void)
	219	{
1da177e4 LT	220	return cpufreq_register_governor(&cpufreq_gov_userspace);
	221	}
	222
	223
	224	static void __exit cpufreq_gov_userspace_exit(void)
	225	{
	226	cpufreq_unregister_governor(&cpufreq_gov_userspace);
1da177e4 LT	227	}
	228
	229
	230	MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
	231	MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
	232	MODULE_LICENSE ("GPL");
	233
	234	fs_initcall(cpufreq_gov_userspace_init);
	235	module_exit(cpufreq_gov_userspace_exit);