[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/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 target_value or 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;
	s32 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 = 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 = 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 = 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 (pm_qos_array[target]->target_value != extreme_value) {
		call_notifier = 1;
		pm_qos_array[target]->target_value = extreme_value;
		pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
			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)
{
	int ret_val;
	unsigned long flags;

	spin_lock_irqsave(&pm_qos_lock, flags);
	ret_val = pm_qos_array[pm_qos_class]->target_value;
	spin_unlock_irqrestore(&pm_qos_lock, flags);

	return ret_val;
}
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 charactoistics.  It recomputes the agregate QoS expectations for
 * the pm_qos_class of parrameters.
 */
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 requierement for the pm_qos_class of parameters along
 * with updating the target pm_qos_class value.
 *
 * If the named request isn't in the lest 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 parrameters 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
 * uppon 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
 * uppon 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;

	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)
			return 0;
	}

	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	*
	27	* mark gross [email protected]
	28	*/
	29
	30	#include <linux/pm_qos_params.h>
	31	#include <linux/sched.h>
	32	#include <linux/spinlock.h>
	33	#include <linux/slab.h>
	34	#include <linux/time.h>
	35	#include <linux/fs.h>
	36	#include <linux/device.h>
	37	#include <linux/miscdevice.h>
	38	#include <linux/string.h>
	39	#include <linux/platform_device.h>
	40	#include <linux/init.h>
	41
	42	#include <linux/uaccess.h>
	43
	44	/*
	45	* locking rule: all changes to target_value or requirements or notifiers lists
	46	* or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
	47	* held, taken with _irqsave. One lock to rule them all
	48	*/
	49	struct requirement_list {
	50	struct list_head list;
	51	union {
	52	s32 value;
	53	s32 usec;
	54	s32 kbps;
	55	};
	56	char *name;
	57	};
	58
	59	static s32 max_compare(s32 v1, s32 v2);
	60	static s32 min_compare(s32 v1, s32 v2);
	61
	62	struct pm_qos_object {
	63	struct requirement_list requirements;
	64	struct blocking_notifier_head *notifiers;
65	struct miscdevice pm_qos_power_miscdev;
66	char *name;
67	s32 default_value;
68	s32 target_value;
69	s32 (*comparitor)(s32, s32);
70	};
71
72	static struct pm_qos_object null_pm_qos;
73	static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
74	static struct pm_qos_object cpu_dma_pm_qos = {
75	.requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)},
76	.notifiers = &cpu_dma_lat_notifier,
77	.name = "cpu_dma_latency",
78	.default_value = 2000 * USEC_PER_SEC,
79	.target_value = 2000 * USEC_PER_SEC,
80	.comparitor = min_compare
81	};
82
83	static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
84	static struct pm_qos_object network_lat_pm_qos = {
85	.requirements = {LIST_HEAD_INIT(network_lat_pm_qos.requirements.list)},
86	.notifiers = &network_lat_notifier,
87	.name = "network_latency",
88	.default_value = 2000 * USEC_PER_SEC,
89	.target_value = 2000 * USEC_PER_SEC,
90	.comparitor = min_compare
91	};
92
93
94	static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
95	static struct pm_qos_object network_throughput_pm_qos = {
96	.requirements =
97	{LIST_HEAD_INIT(network_throughput_pm_qos.requirements.list)},
98	.notifiers = &network_throughput_notifier,
99	.name = "network_throughput",
100	.default_value = 0,
101	.target_value = 0,
102	.comparitor = max_compare
103	};
104
105
106	static struct pm_qos_object *pm_qos_array[] = {
107	&null_pm_qos,
108	&cpu_dma_pm_qos,
109	&network_lat_pm_qos,
110	&network_throughput_pm_qos
111	};
112
113	static DEFINE_SPINLOCK(pm_qos_lock);
114
115	static ssize_t pm_qos_power_write(struct file filp, const char __user buf,
116	size_t count, loff_t *f_pos);
117	static int pm_qos_power_open(struct inode inode, struct file filp);
118	static int pm_qos_power_release(struct inode inode, struct file filp);
119
120	static const struct file_operations pm_qos_power_fops = {
121	.write = pm_qos_power_write,
122	.open = pm_qos_power_open,
123	.release = pm_qos_power_release,
124	};
125
126	/* static helper functions */
127	static s32 max_compare(s32 v1, s32 v2)
128	{
129	return max(v1, v2);
130	}
131
132	static s32 min_compare(s32 v1, s32 v2)
133	{
134	return min(v1, v2);
135	}
136
137
138	static void update_target(int target)
139	{
140	s32 extreme_value;
141	struct requirement_list *node;
142	unsigned long flags;
143	int call_notifier = 0;
144
145	spin_lock_irqsave(&pm_qos_lock, flags);
146	extreme_value = pm_qos_array[target]->default_value;
147	list_for_each_entry(node,
148	&pm_qos_array[target]->requirements.list, list) {
149	extreme_value = pm_qos_array[target]->comparitor(
150	extreme_value, node->value);
151	}
152	if (pm_qos_array[target]->target_value != extreme_value) {
153	call_notifier = 1;
154	pm_qos_array[target]->target_value = extreme_value;
155	pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
156	pm_qos_array[target]->target_value);
157	}
158	spin_unlock_irqrestore(&pm_qos_lock, flags);
159
160	if (call_notifier)
161	blocking_notifier_call_chain(pm_qos_array[target]->notifiers,
162	(unsigned long) extreme_value, NULL);
163	}
164
165	static int register_pm_qos_misc(struct pm_qos_object *qos)
166	{
167	qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
168	qos->pm_qos_power_miscdev.name = qos->name;
169	qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
170
171	return misc_register(&qos->pm_qos_power_miscdev);
172	}
173
174	static int find_pm_qos_object_by_minor(int minor)
175	{
176	int pm_qos_class;
177
178	for (pm_qos_class = 0;
179	pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
180	if (minor ==
181	pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
182	return pm_qos_class;
183	}
184	return -1;
185	}
186
187	/**
188	* pm_qos_requirement - returns current system wide qos expectation
189	* @pm_qos_class: identification of which qos value is requested
190	*
191	* This function returns the current target value in an atomic manner.
192	*/
193	int pm_qos_requirement(int pm_qos_class)
194	{
195	int ret_val;
196	unsigned long flags;
197
198	spin_lock_irqsave(&pm_qos_lock, flags);
199	ret_val = pm_qos_array[pm_qos_class]->target_value;
200	spin_unlock_irqrestore(&pm_qos_lock, flags);
201
202	return ret_val;
203	}
204	EXPORT_SYMBOL_GPL(pm_qos_requirement);
205
206	/**
207	* pm_qos_add_requirement - inserts new qos request into the list
208	* @pm_qos_class: identifies which list of qos request to us
209	* @name: identifies the request
210	* @value: defines the qos request
211	*
212	* This function inserts a new entry in the pm_qos_class list of requested qos
213	* performance charactoistics. It recomputes the agregate QoS expectations for
214	* the pm_qos_class of parrameters.
215	*/
216	int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value)
217	{
218	struct requirement_list *dep;
219	unsigned long flags;
220
221	dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL);
222	if (dep) {
223	if (value == PM_QOS_DEFAULT_VALUE)
224	dep->value = pm_qos_array[pm_qos_class]->default_value;
225	else
226	dep->value = value;
227	dep->name = kstrdup(name, GFP_KERNEL);
228	if (!dep->name)
229	goto cleanup;
230
231	spin_lock_irqsave(&pm_qos_lock, flags);
232	list_add(&dep->list,
233	&pm_qos_array[pm_qos_class]->requirements.list);
234	spin_unlock_irqrestore(&pm_qos_lock, flags);
235	update_target(pm_qos_class);
236
237	return 0;
238	}
239
240	cleanup:
241	kfree(dep);
242	return -ENOMEM;
243	}
244	EXPORT_SYMBOL_GPL(pm_qos_add_requirement);
245
246	/**
247	* pm_qos_update_requirement - modifies an existing qos request
248	* @pm_qos_class: identifies which list of qos request to us
249	* @name: identifies the request
250	* @value: defines the qos request
251	*
252	* Updates an existing qos requierement for the pm_qos_class of parameters along
253	* with updating the target pm_qos_class value.
254	*
255	* If the named request isn't in the lest then no change is made.
256	*/
257	int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value)
258	{
259	unsigned long flags;
260	struct requirement_list *node;
261	int pending_update = 0;
262
263	spin_lock_irqsave(&pm_qos_lock, flags);
264	list_for_each_entry(node,
265	&pm_qos_array[pm_qos_class]->requirements.list, list) {
266	if (strcmp(node->name, name) == 0) {
267	if (new_value == PM_QOS_DEFAULT_VALUE)
268	node->value =
269	pm_qos_array[pm_qos_class]->default_value;
270	else
271	node->value = new_value;
272	pending_update = 1;
273	break;
274	}
275	}
276	spin_unlock_irqrestore(&pm_qos_lock, flags);
277	if (pending_update)
278	update_target(pm_qos_class);
279
280	return 0;
281	}
282	EXPORT_SYMBOL_GPL(pm_qos_update_requirement);
283
284	/**
285	* pm_qos_remove_requirement - modifies an existing qos request
286	* @pm_qos_class: identifies which list of qos request to us
287	* @name: identifies the request
288	*
289	* Will remove named qos request from pm_qos_class list of parrameters and
290	* recompute the current target value for the pm_qos_class.
291	*/
292	void pm_qos_remove_requirement(int pm_qos_class, char *name)
293	{
294	unsigned long flags;
295	struct requirement_list *node;
296	int pending_update = 0;
297
298	spin_lock_irqsave(&pm_qos_lock, flags);
299	list_for_each_entry(node,
300	&pm_qos_array[pm_qos_class]->requirements.list, list) {
301	if (strcmp(node->name, name) == 0) {
302	kfree(node->name);
303	list_del(&node->list);
304	kfree(node);
305	pending_update = 1;
306	break;
307	}
308	}
309	spin_unlock_irqrestore(&pm_qos_lock, flags);
310	if (pending_update)
311	update_target(pm_qos_class);
312	}
313	EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
314
315	/**
316	* pm_qos_add_notifier - sets notification entry for changes to target value
317	* @pm_qos_class: identifies which qos target changes should be notified.
318	* @notifier: notifier block managed by caller.
319	*
320	* will register the notifier into a notification chain that gets called
321	* uppon changes to the pm_qos_class target value.
322	*/
323	int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
324	{
325	int retval;
326
327	retval = blocking_notifier_chain_register(
328	pm_qos_array[pm_qos_class]->notifiers, notifier);
329
330	return retval;
331	}
332	EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
333
334	/**
335	* pm_qos_remove_notifier - deletes notification entry from chain.
336	* @pm_qos_class: identifies which qos target changes are notified.
337	* @notifier: notifier block to be removed.
338	*
339	* will remove the notifier from the notification chain that gets called
340	* uppon changes to the pm_qos_class target value.
341	*/
342	int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
343	{
344	int retval;
345
346	retval = blocking_notifier_chain_unregister(
347	pm_qos_array[pm_qos_class]->notifiers, notifier);
348
349	return retval;
350	}
351	EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
352
353	#define PID_NAME_LEN sizeof("process_1234567890")
354	static char name[PID_NAME_LEN];
355
356	static int pm_qos_power_open(struct inode inode, struct file filp)
357	{
358	int ret;
359	long pm_qos_class;
360
361	pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
362	if (pm_qos_class >= 0) {
363	filp->private_data = (void *)pm_qos_class;
364	sprintf(name, "process_%d", current->pid);
365	ret = pm_qos_add_requirement(pm_qos_class, name,
366	PM_QOS_DEFAULT_VALUE);
367	if (ret >= 0)
368	return 0;
369	}
370
371	return -EPERM;
372	}
373
374	static int pm_qos_power_release(struct inode inode, struct file filp)
375	{
376	int pm_qos_class;
377
378	pm_qos_class = (long)filp->private_data;
379	sprintf(name, "process_%d", current->pid);
380	pm_qos_remove_requirement(pm_qos_class, name);
381
382	return 0;
383	}
384
385	static ssize_t pm_qos_power_write(struct file filp, const char __user buf,
386	size_t count, loff_t *f_pos)
387	{
388	s32 value;
389	int pm_qos_class;
390
391	pm_qos_class = (long)filp->private_data;
392	if (count != sizeof(s32))
393	return -EINVAL;
394	if (copy_from_user(&value, buf, sizeof(s32)))
395	return -EFAULT;
396	sprintf(name, "process_%d", current->pid);
397	pm_qos_update_requirement(pm_qos_class, name, value);
398
399	return sizeof(s32);
400	}
401
402
403	static int __init pm_qos_power_init(void)
404	{
405	int ret = 0;
406
407	ret = register_pm_qos_misc(&cpu_dma_pm_qos);
408	if (ret < 0) {
409	printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
410	return ret;
411	}
412	ret = register_pm_qos_misc(&network_lat_pm_qos);
413	if (ret < 0) {
414	printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
415	return ret;
416	}
417	ret = register_pm_qos_misc(&network_throughput_pm_qos);
418	if (ret < 0)
419	printk(KERN_ERR
420	"pm_qos_param: network_throughput setup failed\n");
421
422	return ret;
423	}
424
425	late_initcall(pm_qos_power_init);