[linux.git] / kernel / pm_qos_params.c

/*
 * This module exposes the interface to kernel space for specifying
 * QoS dependencies.  It provides infrastructure for registration of:
 *
 * Dependents on a QoS value : register requirements
 * Watchers of QoS value : get notified when target QoS value changes
 *
 * This QoS design is best effort based.  Dependents register their QoS needs.
 * Watchers register to keep track of the current QoS needs of the system.
 *
 * There are 3 basic classes of QoS parameter: latency, timeout, throughput
 * each have defined units:
 * latency: usec
 * timeout: usec <-- currently not used.
 * throughput: kbs (kilo byte / sec)
 *
 * There are lists of pm_qos_objects each one wrapping requirements, notifiers
 *
 * User mode requirements on a QOS parameter register themselves to the
 * subsystem by opening the device node /dev/... and writing there request to
 * the node.  As long as the process holds a file handle open to the node the
 * client continues to be accounted for.  Upon file release the usermode
 * requirement is removed and a new qos target is computed.  This way when the
 * requirement that the application has is cleaned up when closes the file
 * pointer or exits the pm_qos_object will get an opportunity to clean up.
 *
 * Mark Gross <[email protected]>
 */

#include <linux/pm_qos_params.h>
#include <linux/sched.h>
#include <linux/smp_lock.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/string.h>
#include <linux/platform_device.h>
#include <linux/init.h>

#include <linux/uaccess.h>

/*
 * locking rule: all changes to requirements or notifiers lists
 * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
 * held, taken with _irqsave.  One lock to rule them all
 */
struct requirement_list {
	struct list_head list;
	union {
		s32 value;
		s32 usec;
		s32 kbps;
	};
	char *name;
};

static s32 max_compare(s32 v1, s32 v2);
static s32 min_compare(s32 v1, s32 v2);

struct pm_qos_object {
	struct requirement_list requirements;
	struct blocking_notifier_head *notifiers;
	struct miscdevice pm_qos_power_miscdev;
	char *name;
	s32 default_value;
	atomic_t target_value;
	s32 (*comparitor)(s32, s32);
};

static struct pm_qos_object null_pm_qos;
static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
static struct pm_qos_object cpu_dma_pm_qos = {
	.requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)},
	.notifiers = &cpu_dma_lat_notifier,
	.name = "cpu_dma_latency",
	.default_value = 2000 * USEC_PER_SEC,
	.target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
	.comparitor = min_compare
};

static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
static struct pm_qos_object network_lat_pm_qos = {
	.requirements = {LIST_HEAD_INIT(network_lat_pm_qos.requirements.list)},
	.notifiers = &network_lat_notifier,
	.name = "network_latency",
	.default_value = 2000 * USEC_PER_SEC,
	.target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
	.comparitor = min_compare
};


static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
static struct pm_qos_object network_throughput_pm_qos = {
	.requirements =
		{LIST_HEAD_INIT(network_throughput_pm_qos.requirements.list)},
	.notifiers = &network_throughput_notifier,
	.name = "network_throughput",
	.default_value = 0,
	.target_value = ATOMIC_INIT(0),
	.comparitor = max_compare
};


static struct pm_qos_object *pm_qos_array[] = {
	&null_pm_qos,
	&cpu_dma_pm_qos,
	&network_lat_pm_qos,
	&network_throughput_pm_qos
};

static DEFINE_SPINLOCK(pm_qos_lock);

static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
		size_t count, loff_t *f_pos);
static int pm_qos_power_open(struct inode *inode, struct file *filp);
static int pm_qos_power_release(struct inode *inode, struct file *filp);

static const struct file_operations pm_qos_power_fops = {
	.write = pm_qos_power_write,
	.open = pm_qos_power_open,
	.release = pm_qos_power_release,
};

/* static helper functions */
static s32 max_compare(s32 v1, s32 v2)
{
	return max(v1, v2);
}

static s32 min_compare(s32 v1, s32 v2)
{
	return min(v1, v2);
}


static void update_target(int target)
{
	s32 extreme_value;
	struct requirement_list *node;
	unsigned long flags;
	int call_notifier = 0;

	spin_lock_irqsave(&pm_qos_lock, flags);
	extreme_value = pm_qos_array[target]->default_value;
	list_for_each_entry(node,
			&pm_qos_array[target]->requirements.list, list) {
		extreme_value = pm_qos_array[target]->comparitor(
				extreme_value, node->value);
	}
	if (atomic_read(&pm_qos_array[target]->target_value) != extreme_value) {
		call_notifier = 1;
		atomic_set(&pm_qos_array[target]->target_value, extreme_value);
		pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
			atomic_read(&pm_qos_array[target]->target_value));
	}
	spin_unlock_irqrestore(&pm_qos_lock, flags);

	if (call_notifier)
		blocking_notifier_call_chain(pm_qos_array[target]->notifiers,
			(unsigned long) extreme_value, NULL);
}

static int register_pm_qos_misc(struct pm_qos_object *qos)
{
	qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
	qos->pm_qos_power_miscdev.name = qos->name;
	qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;

	return misc_register(&qos->pm_qos_power_miscdev);
}

static int find_pm_qos_object_by_minor(int minor)
{
	int pm_qos_class;

	for (pm_qos_class = 0;
		pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
		if (minor ==
			pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
			return pm_qos_class;
	}
	return -1;
}

/**
 * pm_qos_requirement - returns current system wide qos expectation
 * @pm_qos_class: identification of which qos value is requested
 *
 * This function returns the current target value in an atomic manner.
 */
int pm_qos_requirement(int pm_qos_class)
{
	return atomic_read(&pm_qos_array[pm_qos_class]->target_value);
}
EXPORT_SYMBOL_GPL(pm_qos_requirement);

/**
 * pm_qos_add_requirement - inserts new qos request into the list
 * @pm_qos_class: identifies which list of qos request to us
 * @name: identifies the request
 * @value: defines the qos request
 *
 * This function inserts a new entry in the pm_qos_class list of requested qos
 * performance characteristics.  It recomputes the aggregate QoS expectations
 * for the pm_qos_class of parameters.
 */
int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value)
{
	struct requirement_list *dep;
	unsigned long flags;

	dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL);
	if (dep) {
		if (value == PM_QOS_DEFAULT_VALUE)
			dep->value = pm_qos_array[pm_qos_class]->default_value;
		else
			dep->value = value;
		dep->name = kstrdup(name, GFP_KERNEL);
		if (!dep->name)
			goto cleanup;

		spin_lock_irqsave(&pm_qos_lock, flags);
		list_add(&dep->list,
			&pm_qos_array[pm_qos_class]->requirements.list);
		spin_unlock_irqrestore(&pm_qos_lock, flags);
		update_target(pm_qos_class);

		return 0;
	}

cleanup:
	kfree(dep);
	return -ENOMEM;
}
EXPORT_SYMBOL_GPL(pm_qos_add_requirement);

/**
 * pm_qos_update_requirement - modifies an existing qos request
 * @pm_qos_class: identifies which list of qos request to us
 * @name: identifies the request
 * @value: defines the qos request
 *
 * Updates an existing qos requirement for the pm_qos_class of parameters along
 * with updating the target pm_qos_class value.
 *
 * If the named request isn't in the list then no change is made.
 */
int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value)
{
	unsigned long flags;
	struct requirement_list *node;
	int pending_update = 0;

	spin_lock_irqsave(&pm_qos_lock, flags);
	list_for_each_entry(node,
		&pm_qos_array[pm_qos_class]->requirements.list, list) {
		if (strcmp(node->name, name) == 0) {
			if (new_value == PM_QOS_DEFAULT_VALUE)
				node->value =
				pm_qos_array[pm_qos_class]->default_value;
			else
				node->value = new_value;
			pending_update = 1;
			break;
		}
	}
	spin_unlock_irqrestore(&pm_qos_lock, flags);
	if (pending_update)
		update_target(pm_qos_class);

	return 0;
}
EXPORT_SYMBOL_GPL(pm_qos_update_requirement);

/**
 * pm_qos_remove_requirement - modifies an existing qos request
 * @pm_qos_class: identifies which list of qos request to us
 * @name: identifies the request
 *
 * Will remove named qos request from pm_qos_class list of parameters and
 * recompute the current target value for the pm_qos_class.
 */
void pm_qos_remove_requirement(int pm_qos_class, char *name)
{
	unsigned long flags;
	struct requirement_list *node;
	int pending_update = 0;

	spin_lock_irqsave(&pm_qos_lock, flags);
	list_for_each_entry(node,
		&pm_qos_array[pm_qos_class]->requirements.list, list) {
		if (strcmp(node->name, name) == 0) {
			kfree(node->name);
			list_del(&node->list);
			kfree(node);
			pending_update = 1;
			break;
		}
	}
	spin_unlock_irqrestore(&pm_qos_lock, flags);
	if (pending_update)
		update_target(pm_qos_class);
}
EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);

/**
 * pm_qos_add_notifier - sets notification entry for changes to target value
 * @pm_qos_class: identifies which qos target changes should be notified.
 * @notifier: notifier block managed by caller.
 *
 * will register the notifier into a notification chain that gets called
 * upon changes to the pm_qos_class target value.
 */
 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
{
	int retval;

	retval = blocking_notifier_chain_register(
			pm_qos_array[pm_qos_class]->notifiers, notifier);

	return retval;
}
EXPORT_SYMBOL_GPL(pm_qos_add_notifier);

/**
 * pm_qos_remove_notifier - deletes notification entry from chain.
 * @pm_qos_class: identifies which qos target changes are notified.
 * @notifier: notifier block to be removed.
 *
 * will remove the notifier from the notification chain that gets called
 * upon changes to the pm_qos_class target value.
 */
int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
{
	int retval;

	retval = blocking_notifier_chain_unregister(
			pm_qos_array[pm_qos_class]->notifiers, notifier);

	return retval;
}
EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);

#define PID_NAME_LEN sizeof("process_1234567890")
static char name[PID_NAME_LEN];

static int pm_qos_power_open(struct inode *inode, struct file *filp)
{
	int ret;
	long pm_qos_class;

	lock_kernel();
	pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
	if (pm_qos_class >= 0) {
		filp->private_data = (void *)pm_qos_class;
		sprintf(name, "process_%d", current->pid);
		ret = pm_qos_add_requirement(pm_qos_class, name,
					PM_QOS_DEFAULT_VALUE);
		if (ret >= 0) {
			unlock_kernel();
			return 0;
		}
	}
	unlock_kernel();

	return -EPERM;
}

static int pm_qos_power_release(struct inode *inode, struct file *filp)
{
	int pm_qos_class;

	pm_qos_class = (long)filp->private_data;
	sprintf(name, "process_%d", current->pid);
	pm_qos_remove_requirement(pm_qos_class, name);

	return 0;
}

static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
		size_t count, loff_t *f_pos)
{
	s32 value;
	int pm_qos_class;

	pm_qos_class = (long)filp->private_data;
	if (count != sizeof(s32))
		return -EINVAL;
	if (copy_from_user(&value, buf, sizeof(s32)))
		return -EFAULT;
	sprintf(name, "process_%d", current->pid);
	pm_qos_update_requirement(pm_qos_class, name, value);

	return  sizeof(s32);
}


static int __init pm_qos_power_init(void)
{
	int ret = 0;

	ret = register_pm_qos_misc(&cpu_dma_pm_qos);
	if (ret < 0) {
		printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
		return ret;
	}
	ret = register_pm_qos_misc(&network_lat_pm_qos);
	if (ret < 0) {
		printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
		return ret;
	}
	ret = register_pm_qos_misc(&network_throughput_pm_qos);
	if (ret < 0)
		printk(KERN_ERR
			"pm_qos_param: network_throughput setup failed\n");

	return ret;
}

late_initcall(pm_qos_power_init);
Commit	Line	Data
d82b3518 MG	1	/*
	2	* This module exposes the interface to kernel space for specifying
	3	* QoS dependencies. It provides infrastructure for registration of:
	4	*
	5	* Dependents on a QoS value : register requirements
	6	* Watchers of QoS value : get notified when target QoS value changes
	7	*
	8	* This QoS design is best effort based. Dependents register their QoS needs.
	9	* Watchers register to keep track of the current QoS needs of the system.
	10	*
	11	* There are 3 basic classes of QoS parameter: latency, timeout, throughput
	12	* each have defined units:
	13	* latency: usec
	14	* timeout: usec <-- currently not used.
	15	* throughput: kbs (kilo byte / sec)
	16	*
	17	* There are lists of pm_qos_objects each one wrapping requirements, notifiers
	18	*
	19	* User mode requirements on a QOS parameter register themselves to the
	20	* subsystem by opening the device node /dev/... and writing there request to
	21	* the node. As long as the process holds a file handle open to the node the
	22	* client continues to be accounted for. Upon file release the usermode
	23	* requirement is removed and a new qos target is computed. This way when the
	24	* requirement that the application has is cleaned up when closes the file
	25	* pointer or exits the pm_qos_object will get an opportunity to clean up.
	26	*
bf1db69f	27	* Mark Gross <[email protected]>
d82b3518 MG	28	*/
	29
	30	#include <linux/pm_qos_params.h>
	31	#include <linux/sched.h>
db26e64d	32	#include <linux/smp_lock.h>
d82b3518 MG	33	#include <linux/spinlock.h>
	34	#include <linux/slab.h>
	35	#include <linux/time.h>
	36	#include <linux/fs.h>
	37	#include <linux/device.h>
	38	#include <linux/miscdevice.h>
	39	#include <linux/string.h>
	40	#include <linux/platform_device.h>
	41	#include <linux/init.h>
	42
	43	#include <linux/uaccess.h>
	44
	45	/*
9d359357	46	* locking rule: all changes to requirements or notifiers lists
d82b3518 MG	47	* or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
	48	* held, taken with _irqsave. One lock to rule them all
	49	*/
	50	struct requirement_list {
	51	struct list_head list;
	52	union {
	53	s32 value;
	54	s32 usec;
	55	s32 kbps;
	56	};
	57	char *name;
	58	};
	59
	60	static s32 max_compare(s32 v1, s32 v2);
	61	static s32 min_compare(s32 v1, s32 v2);
	62
	63	struct pm_qos_object {
	64	struct requirement_list requirements;
	65	struct blocking_notifier_head *notifiers;
	66	struct miscdevice pm_qos_power_miscdev;
	67	char *name;
	68	s32 default_value;
9d359357	69	atomic_t target_value;
d82b3518 MG	70	s32 (*comparitor)(s32, s32);
	71	};
	72
	73	static struct pm_qos_object null_pm_qos;
	74	static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
	75	static struct pm_qos_object cpu_dma_pm_qos = {
	76	.requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)},
	77	.notifiers = &cpu_dma_lat_notifier,
	78	.name = "cpu_dma_latency",
	79	.default_value = 2000 * USEC_PER_SEC,
9d359357	80	.target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
d82b3518 MG	81	.comparitor = min_compare
	82	};
	83
	84	static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
	85	static struct pm_qos_object network_lat_pm_qos = {
	86	.requirements = {LIST_HEAD_INIT(network_lat_pm_qos.requirements.list)},
	87	.notifiers = &network_lat_notifier,
	88	.name = "network_latency",
	89	.default_value = 2000 * USEC_PER_SEC,
9d359357	90	.target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
d82b3518 MG	91	.comparitor = min_compare
	92	};
	93
	94
	95	static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
	96	static struct pm_qos_object network_throughput_pm_qos = {
	97	.requirements =
	98	{LIST_HEAD_INIT(network_throughput_pm_qos.requirements.list)},
	99	.notifiers = &network_throughput_notifier,
	100	.name = "network_throughput",
	101	.default_value = 0,
9d359357	102	.target_value = ATOMIC_INIT(0),
d82b3518 MG	103	.comparitor = max_compare
	104	};
	105
	106
	107	static struct pm_qos_object *pm_qos_array[] = {
	108	&null_pm_qos,
	109	&cpu_dma_pm_qos,
	110	&network_lat_pm_qos,
	111	&network_throughput_pm_qos
	112	};
	113
	114	static DEFINE_SPINLOCK(pm_qos_lock);
	115
	116	static ssize_t pm_qos_power_write(struct file filp, const char __user buf,
	117	size_t count, loff_t *f_pos);
	118	static int pm_qos_power_open(struct inode inode, struct file filp);
	119	static int pm_qos_power_release(struct inode inode, struct file filp);
	120
	121	static const struct file_operations pm_qos_power_fops = {
	122	.write = pm_qos_power_write,
	123	.open = pm_qos_power_open,
	124	.release = pm_qos_power_release,
	125	};
	126
	127	/* static helper functions */
	128	static s32 max_compare(s32 v1, s32 v2)
	129	{
	130	return max(v1, v2);
	131	}
	132
	133	static s32 min_compare(s32 v1, s32 v2)
	134	{
	135	return min(v1, v2);
	136	}
	137
	138
	139	static void update_target(int target)
	140	{
	141	s32 extreme_value;
	142	struct requirement_list *node;
	143	unsigned long flags;
	144	int call_notifier = 0;
	145
	146	spin_lock_irqsave(&pm_qos_lock, flags);
	147	extreme_value = pm_qos_array[target]->default_value;
	148	list_for_each_entry(node,
	149	&pm_qos_array[target]->requirements.list, list) {
	150	extreme_value = pm_qos_array[target]->comparitor(
	151	extreme_value, node->value);
	152	}
9d359357	153	if (atomic_read(&pm_qos_array[target]->target_value) != extreme_value) {
d82b3518	154	call_notifier = 1;
9d359357	155	atomic_set(&pm_qos_array[target]->target_value, extreme_value);
d82b3518	156	pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
9d359357	157	atomic_read(&pm_qos_array[target]->target_value));
d82b3518 MG	158	}
	159	spin_unlock_irqrestore(&pm_qos_lock, flags);
	160
	161	if (call_notifier)
	162	blocking_notifier_call_chain(pm_qos_array[target]->notifiers,
	163	(unsigned long) extreme_value, NULL);
	164	}
	165
	166	static int register_pm_qos_misc(struct pm_qos_object *qos)
	167	{
	168	qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
	169	qos->pm_qos_power_miscdev.name = qos->name;
	170	qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
	171
	172	return misc_register(&qos->pm_qos_power_miscdev);
	173	}
	174
	175	static int find_pm_qos_object_by_minor(int minor)
	176	{
	177	int pm_qos_class;
	178
	179	for (pm_qos_class = 0;
	180	pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
	181	if (minor ==
	182	pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
	183	return pm_qos_class;
	184	}
	185	return -1;
	186	}
	187
	188	/**
	189	* pm_qos_requirement - returns current system wide qos expectation
	190	* @pm_qos_class: identification of which qos value is requested
	191	*
	192	* This function returns the current target value in an atomic manner.
	193	*/
	194	int pm_qos_requirement(int pm_qos_class)
	195	{
9d359357	196	return atomic_read(&pm_qos_array[pm_qos_class]->target_value);
d82b3518 MG	197	}
	198	EXPORT_SYMBOL_GPL(pm_qos_requirement);
	199
	200	/**
	201	* pm_qos_add_requirement - inserts new qos request into the list
	202	* @pm_qos_class: identifies which list of qos request to us
	203	* @name: identifies the request
	204	* @value: defines the qos request
	205	*
	206	* This function inserts a new entry in the pm_qos_class list of requested qos
bf1db69f RH	207	* performance characteristics. It recomputes the aggregate QoS expectations
bf1db69f RH	208	* for the pm_qos_class of parameters.
d82b3518 MG	209	*/
	210	int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value)
	211	{
	212	struct requirement_list *dep;
	213	unsigned long flags;
	214
	215	dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL);
	216	if (dep) {
	217	if (value == PM_QOS_DEFAULT_VALUE)
	218	dep->value = pm_qos_array[pm_qos_class]->default_value;
	219	else
	220	dep->value = value;
	221	dep->name = kstrdup(name, GFP_KERNEL);
	222	if (!dep->name)
	223	goto cleanup;
	224
	225	spin_lock_irqsave(&pm_qos_lock, flags);
	226	list_add(&dep->list,
	227	&pm_qos_array[pm_qos_class]->requirements.list);
	228	spin_unlock_irqrestore(&pm_qos_lock, flags);
	229	update_target(pm_qos_class);
	230
	231	return 0;
	232	}
	233
	234	cleanup:
	235	kfree(dep);
	236	return -ENOMEM;
	237	}
	238	EXPORT_SYMBOL_GPL(pm_qos_add_requirement);
	239
	240	/**
	241	* pm_qos_update_requirement - modifies an existing qos request
	242	* @pm_qos_class: identifies which list of qos request to us
	243	* @name: identifies the request
	244	* @value: defines the qos request
	245	*
bf1db69f	246	* Updates an existing qos requirement for the pm_qos_class of parameters along
d82b3518 MG	247	* with updating the target pm_qos_class value.
d82b3518 MG	248	*
bf1db69f	249	* If the named request isn't in the list then no change is made.
d82b3518 MG	250	*/
	251	int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value)
	252	{
	253	unsigned long flags;
	254	struct requirement_list *node;
	255	int pending_update = 0;
	256
	257	spin_lock_irqsave(&pm_qos_lock, flags);
	258	list_for_each_entry(node,
	259	&pm_qos_array[pm_qos_class]->requirements.list, list) {
	260	if (strcmp(node->name, name) == 0) {
	261	if (new_value == PM_QOS_DEFAULT_VALUE)
	262	node->value =
	263	pm_qos_array[pm_qos_class]->default_value;
	264	else
	265	node->value = new_value;
	266	pending_update = 1;
	267	break;
	268	}
	269	}
	270	spin_unlock_irqrestore(&pm_qos_lock, flags);
	271	if (pending_update)
	272	update_target(pm_qos_class);
	273
	274	return 0;
	275	}
	276	EXPORT_SYMBOL_GPL(pm_qos_update_requirement);
	277
	278	/**
	279	* pm_qos_remove_requirement - modifies an existing qos request
	280	* @pm_qos_class: identifies which list of qos request to us
	281	* @name: identifies the request
	282	*
bf1db69f	283	* Will remove named qos request from pm_qos_class list of parameters and
d82b3518 MG	284	* recompute the current target value for the pm_qos_class.
	285	*/
	286	void pm_qos_remove_requirement(int pm_qos_class, char *name)
	287	{
	288	unsigned long flags;
	289	struct requirement_list *node;
	290	int pending_update = 0;
	291
	292	spin_lock_irqsave(&pm_qos_lock, flags);
	293	list_for_each_entry(node,
	294	&pm_qos_array[pm_qos_class]->requirements.list, list) {
	295	if (strcmp(node->name, name) == 0) {
	296	kfree(node->name);
	297	list_del(&node->list);
	298	kfree(node);
	299	pending_update = 1;
	300	break;
	301	}
	302	}
	303	spin_unlock_irqrestore(&pm_qos_lock, flags);
	304	if (pending_update)
	305	update_target(pm_qos_class);
	306	}
	307	EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
	308
	309	/**
	310	* pm_qos_add_notifier - sets notification entry for changes to target value
	311	* @pm_qos_class: identifies which qos target changes should be notified.
	312	* @notifier: notifier block managed by caller.
	313	*
	314	* will register the notifier into a notification chain that gets called
bf1db69f	315	* upon changes to the pm_qos_class target value.
d82b3518 MG	316	*/
	317	int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
	318	{
	319	int retval;
	320
	321	retval = blocking_notifier_chain_register(
	322	pm_qos_array[pm_qos_class]->notifiers, notifier);
	323
	324	return retval;
	325	}
	326	EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
	327
	328	/**
	329	* pm_qos_remove_notifier - deletes notification entry from chain.
	330	* @pm_qos_class: identifies which qos target changes are notified.
	331	* @notifier: notifier block to be removed.
	332	*
	333	* will remove the notifier from the notification chain that gets called
bf1db69f	334	* upon changes to the pm_qos_class target value.
d82b3518 MG	335	*/
	336	int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
	337	{
	338	int retval;
	339
	340	retval = blocking_notifier_chain_unregister(
	341	pm_qos_array[pm_qos_class]->notifiers, notifier);
	342
	343	return retval;
	344	}
	345	EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
	346
	347	#define PID_NAME_LEN sizeof("process_1234567890")
	348	static char name[PID_NAME_LEN];
	349
	350	static int pm_qos_power_open(struct inode inode, struct file filp)
	351	{
	352	int ret;
	353	long pm_qos_class;
	354
db26e64d	355	lock_kernel();
d82b3518 MG	356	pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
	357	if (pm_qos_class >= 0) {
	358	filp->private_data = (void *)pm_qos_class;
	359	sprintf(name, "process_%d", current->pid);
	360	ret = pm_qos_add_requirement(pm_qos_class, name,
	361	PM_QOS_DEFAULT_VALUE);
db26e64d AB	362	if (ret >= 0) {
db26e64d AB	363	unlock_kernel();
d82b3518	364	return 0;
db26e64d	365	}
d82b3518	366	}
db26e64d	367	unlock_kernel();
d82b3518 MG	368
	369	return -EPERM;
	370	}
	371
	372	static int pm_qos_power_release(struct inode inode, struct file filp)
	373	{
	374	int pm_qos_class;
	375
	376	pm_qos_class = (long)filp->private_data;
	377	sprintf(name, "process_%d", current->pid);
	378	pm_qos_remove_requirement(pm_qos_class, name);
	379
	380	return 0;
	381	}
	382
	383	static ssize_t pm_qos_power_write(struct file filp, const char __user buf,
	384	size_t count, loff_t *f_pos)
	385	{
	386	s32 value;
	387	int pm_qos_class;
	388
	389	pm_qos_class = (long)filp->private_data;
	390	if (count != sizeof(s32))
	391	return -EINVAL;
	392	if (copy_from_user(&value, buf, sizeof(s32)))
	393	return -EFAULT;
	394	sprintf(name, "process_%d", current->pid);
	395	pm_qos_update_requirement(pm_qos_class, name, value);
	396
	397	return sizeof(s32);
	398	}
	399
	400
	401	static int __init pm_qos_power_init(void)
	402	{
	403	int ret = 0;
	404
	405	ret = register_pm_qos_misc(&cpu_dma_pm_qos);
	406	if (ret < 0) {
	407	printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
	408	return ret;
	409	}
	410	ret = register_pm_qos_misc(&network_lat_pm_qos);
	411	if (ret < 0) {
	412	printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
	413	return ret;
	414	}
	415	ret = register_pm_qos_misc(&network_throughput_pm_qos);
	416	if (ret < 0)
	417	printk(KERN_ERR
	418	"pm_qos_param: network_throughput setup failed\n");
	419
	420	return ret;
	421	}
	422
	423	late_initcall(pm_qos_power_init);