cifs: clean up check_rfc1002_header
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / pm_qos_params.c
blob37f05d0f07939e696eb8657fbd80ce08bab7ef15
1 /*
2 * This module exposes the interface to kernel space for specifying
3 * QoS dependencies. It provides infrastructure for registration of:
5 * Dependents on a QoS value : register requests
6 * Watchers of QoS value : get notified when target QoS value changes
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.
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)
17 * There are lists of pm_qos_objects each one wrapping requests, notifiers
19 * User mode requests 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 * request is removed and a new qos target is computed. This way when the
24 * request 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.
27 * Mark Gross <mgross@linux.intel.com>
30 /*#define DEBUG*/
32 #include <linux/pm_qos_params.h>
33 #include <linux/sched.h>
34 #include <linux/spinlock.h>
35 #include <linux/slab.h>
36 #include <linux/time.h>
37 #include <linux/fs.h>
38 #include <linux/device.h>
39 #include <linux/miscdevice.h>
40 #include <linux/string.h>
41 #include <linux/platform_device.h>
42 #include <linux/init.h>
43 #include <linux/kernel.h>
45 #include <linux/uaccess.h>
48 * locking rule: all changes to requests or notifiers lists
49 * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
50 * held, taken with _irqsave. One lock to rule them all
52 enum pm_qos_type {
53 PM_QOS_MAX, /* return the largest value */
54 PM_QOS_MIN /* return the smallest value */
58 * Note: The lockless read path depends on the CPU accessing
59 * target_value atomically. Atomic access is only guaranteed on all CPU
60 * types linux supports for 32 bit quantites
62 struct pm_qos_object {
63 struct plist_head requests;
64 struct blocking_notifier_head *notifiers;
65 struct miscdevice pm_qos_power_miscdev;
66 char *name;
67 s32 target_value; /* Do not change to 64 bit */
68 s32 default_value;
69 enum pm_qos_type type;
72 static DEFINE_SPINLOCK(pm_qos_lock);
74 static struct pm_qos_object null_pm_qos;
75 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
76 static struct pm_qos_object cpu_dma_pm_qos = {
77 .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests),
78 .notifiers = &cpu_dma_lat_notifier,
79 .name = "cpu_dma_latency",
80 .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
81 .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
82 .type = PM_QOS_MIN,
85 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
86 static struct pm_qos_object network_lat_pm_qos = {
87 .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests),
88 .notifiers = &network_lat_notifier,
89 .name = "network_latency",
90 .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
91 .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
92 .type = PM_QOS_MIN
96 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
97 static struct pm_qos_object network_throughput_pm_qos = {
98 .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests),
99 .notifiers = &network_throughput_notifier,
100 .name = "network_throughput",
101 .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
102 .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
103 .type = PM_QOS_MAX,
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
114 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
115 size_t count, loff_t *f_pos);
116 static ssize_t pm_qos_power_read(struct file *filp, 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);
121 static const struct file_operations pm_qos_power_fops = {
122 .write = pm_qos_power_write,
123 .read = pm_qos_power_read,
124 .open = pm_qos_power_open,
125 .release = pm_qos_power_release,
126 .llseek = noop_llseek,
129 /* unlocked internal variant */
130 static inline int pm_qos_get_value(struct pm_qos_object *o)
132 if (plist_head_empty(&o->requests))
133 return o->default_value;
135 switch (o->type) {
136 case PM_QOS_MIN:
137 return plist_first(&o->requests)->prio;
139 case PM_QOS_MAX:
140 return plist_last(&o->requests)->prio;
142 default:
143 /* runtime check for not using enum */
144 BUG();
148 static inline s32 pm_qos_read_value(struct pm_qos_object *o)
150 return o->target_value;
153 static inline void pm_qos_set_value(struct pm_qos_object *o, s32 value)
155 o->target_value = value;
158 static void update_target(struct pm_qos_object *o, struct plist_node *node,
159 int del, int value)
161 unsigned long flags;
162 int prev_value, curr_value;
164 spin_lock_irqsave(&pm_qos_lock, flags);
165 prev_value = pm_qos_get_value(o);
166 /* PM_QOS_DEFAULT_VALUE is a signal that the value is unchanged */
167 if (value != PM_QOS_DEFAULT_VALUE) {
169 * to change the list, we atomically remove, reinit
170 * with new value and add, then see if the extremal
171 * changed
173 plist_del(node, &o->requests);
174 plist_node_init(node, value);
175 plist_add(node, &o->requests);
176 } else if (del) {
177 plist_del(node, &o->requests);
178 } else {
179 plist_add(node, &o->requests);
181 curr_value = pm_qos_get_value(o);
182 pm_qos_set_value(o, curr_value);
183 spin_unlock_irqrestore(&pm_qos_lock, flags);
185 if (prev_value != curr_value)
186 blocking_notifier_call_chain(o->notifiers,
187 (unsigned long)curr_value,
188 NULL);
191 static int register_pm_qos_misc(struct pm_qos_object *qos)
193 qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
194 qos->pm_qos_power_miscdev.name = qos->name;
195 qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
197 return misc_register(&qos->pm_qos_power_miscdev);
200 static int find_pm_qos_object_by_minor(int minor)
202 int pm_qos_class;
204 for (pm_qos_class = 0;
205 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
206 if (minor ==
207 pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
208 return pm_qos_class;
210 return -1;
214 * pm_qos_request - returns current system wide qos expectation
215 * @pm_qos_class: identification of which qos value is requested
217 * This function returns the current target value.
219 int pm_qos_request(int pm_qos_class)
221 return pm_qos_read_value(pm_qos_array[pm_qos_class]);
223 EXPORT_SYMBOL_GPL(pm_qos_request);
225 int pm_qos_request_active(struct pm_qos_request_list *req)
227 return req->pm_qos_class != 0;
229 EXPORT_SYMBOL_GPL(pm_qos_request_active);
232 * pm_qos_add_request - inserts new qos request into the list
233 * @dep: pointer to a preallocated handle
234 * @pm_qos_class: identifies which list of qos request to use
235 * @value: defines the qos request
237 * This function inserts a new entry in the pm_qos_class list of requested qos
238 * performance characteristics. It recomputes the aggregate QoS expectations
239 * for the pm_qos_class of parameters and initializes the pm_qos_request_list
240 * handle. Caller needs to save this handle for later use in updates and
241 * removal.
244 void pm_qos_add_request(struct pm_qos_request_list *dep,
245 int pm_qos_class, s32 value)
247 struct pm_qos_object *o = pm_qos_array[pm_qos_class];
248 int new_value;
250 if (pm_qos_request_active(dep)) {
251 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
252 return;
254 if (value == PM_QOS_DEFAULT_VALUE)
255 new_value = o->default_value;
256 else
257 new_value = value;
258 plist_node_init(&dep->list, new_value);
259 dep->pm_qos_class = pm_qos_class;
260 update_target(o, &dep->list, 0, PM_QOS_DEFAULT_VALUE);
262 EXPORT_SYMBOL_GPL(pm_qos_add_request);
265 * pm_qos_update_request - modifies an existing qos request
266 * @pm_qos_req : handle to list element holding a pm_qos request to use
267 * @value: defines the qos request
269 * Updates an existing qos request for the pm_qos_class of parameters along
270 * with updating the target pm_qos_class value.
272 * Attempts are made to make this code callable on hot code paths.
274 void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
275 s32 new_value)
277 s32 temp;
278 struct pm_qos_object *o;
280 if (!pm_qos_req) /*guard against callers passing in null */
281 return;
283 if (!pm_qos_request_active(pm_qos_req)) {
284 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
285 return;
288 o = pm_qos_array[pm_qos_req->pm_qos_class];
290 if (new_value == PM_QOS_DEFAULT_VALUE)
291 temp = o->default_value;
292 else
293 temp = new_value;
295 if (temp != pm_qos_req->list.prio)
296 update_target(o, &pm_qos_req->list, 0, temp);
298 EXPORT_SYMBOL_GPL(pm_qos_update_request);
301 * pm_qos_remove_request - modifies an existing qos request
302 * @pm_qos_req: handle to request list element
304 * Will remove pm qos request from the list of requests and
305 * recompute the current target value for the pm_qos_class. Call this
306 * on slow code paths.
308 void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req)
310 struct pm_qos_object *o;
312 if (pm_qos_req == NULL)
313 return;
314 /* silent return to keep pcm code cleaner */
316 if (!pm_qos_request_active(pm_qos_req)) {
317 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
318 return;
321 o = pm_qos_array[pm_qos_req->pm_qos_class];
322 update_target(o, &pm_qos_req->list, 1, PM_QOS_DEFAULT_VALUE);
323 memset(pm_qos_req, 0, sizeof(*pm_qos_req));
325 EXPORT_SYMBOL_GPL(pm_qos_remove_request);
328 * pm_qos_add_notifier - sets notification entry for changes to target value
329 * @pm_qos_class: identifies which qos target changes should be notified.
330 * @notifier: notifier block managed by caller.
332 * will register the notifier into a notification chain that gets called
333 * upon changes to the pm_qos_class target value.
335 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
337 int retval;
339 retval = blocking_notifier_chain_register(
340 pm_qos_array[pm_qos_class]->notifiers, notifier);
342 return retval;
344 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
347 * pm_qos_remove_notifier - deletes notification entry from chain.
348 * @pm_qos_class: identifies which qos target changes are notified.
349 * @notifier: notifier block to be removed.
351 * will remove the notifier from the notification chain that gets called
352 * upon changes to the pm_qos_class target value.
354 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
356 int retval;
358 retval = blocking_notifier_chain_unregister(
359 pm_qos_array[pm_qos_class]->notifiers, notifier);
361 return retval;
363 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
365 static int pm_qos_power_open(struct inode *inode, struct file *filp)
367 long pm_qos_class;
369 pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
370 if (pm_qos_class >= 0) {
371 struct pm_qos_request_list *req = kzalloc(sizeof(*req), GFP_KERNEL);
372 if (!req)
373 return -ENOMEM;
375 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
376 filp->private_data = req;
378 if (filp->private_data)
379 return 0;
381 return -EPERM;
384 static int pm_qos_power_release(struct inode *inode, struct file *filp)
386 struct pm_qos_request_list *req;
388 req = filp->private_data;
389 pm_qos_remove_request(req);
390 kfree(req);
392 return 0;
396 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
397 size_t count, loff_t *f_pos)
399 s32 value;
400 unsigned long flags;
401 struct pm_qos_object *o;
402 struct pm_qos_request_list *pm_qos_req = filp->private_data;
404 if (!pm_qos_req)
405 return -EINVAL;
406 if (!pm_qos_request_active(pm_qos_req))
407 return -EINVAL;
409 o = pm_qos_array[pm_qos_req->pm_qos_class];
410 spin_lock_irqsave(&pm_qos_lock, flags);
411 value = pm_qos_get_value(o);
412 spin_unlock_irqrestore(&pm_qos_lock, flags);
414 return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
417 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
418 size_t count, loff_t *f_pos)
420 s32 value;
421 struct pm_qos_request_list *pm_qos_req;
423 if (count == sizeof(s32)) {
424 if (copy_from_user(&value, buf, sizeof(s32)))
425 return -EFAULT;
426 } else if (count <= 11) { /* ASCII perhaps? */
427 char ascii_value[11];
428 unsigned long int ulval;
429 int ret;
431 if (copy_from_user(ascii_value, buf, count))
432 return -EFAULT;
434 if (count > 10) {
435 if (ascii_value[10] == '\n')
436 ascii_value[10] = '\0';
437 else
438 return -EINVAL;
439 } else {
440 ascii_value[count] = '\0';
442 ret = strict_strtoul(ascii_value, 16, &ulval);
443 if (ret) {
444 pr_debug("%s, 0x%lx, 0x%x\n", ascii_value, ulval, ret);
445 return -EINVAL;
447 value = (s32)lower_32_bits(ulval);
448 } else {
449 return -EINVAL;
452 pm_qos_req = filp->private_data;
453 pm_qos_update_request(pm_qos_req, value);
455 return count;
459 static int __init pm_qos_power_init(void)
461 int ret = 0;
463 ret = register_pm_qos_misc(&cpu_dma_pm_qos);
464 if (ret < 0) {
465 printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
466 return ret;
468 ret = register_pm_qos_misc(&network_lat_pm_qos);
469 if (ret < 0) {
470 printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
471 return ret;
473 ret = register_pm_qos_misc(&network_throughput_pm_qos);
474 if (ret < 0)
475 printk(KERN_ERR
476 "pm_qos_param: network_throughput setup failed\n");
478 return ret;
481 late_initcall(pm_qos_power_init);