[NFS] Set CONFIG_KEYS when CONFIG_NFS_USE_KERNEL_DNS is set
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / pm_qos_params.c
blob996a4dec5f968406aae7ef9b79240768da1ffddb
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>
44 #include <linux/uaccess.h>
47 * locking rule: all changes to requests or notifiers lists
48 * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
49 * held, taken with _irqsave. One lock to rule them all
51 enum pm_qos_type {
52 PM_QOS_MAX, /* return the largest value */
53 PM_QOS_MIN /* return the smallest value */
56 struct pm_qos_object {
57 struct plist_head requests;
58 struct blocking_notifier_head *notifiers;
59 struct miscdevice pm_qos_power_miscdev;
60 char *name;
61 s32 default_value;
62 enum pm_qos_type type;
65 static DEFINE_SPINLOCK(pm_qos_lock);
67 static struct pm_qos_object null_pm_qos;
68 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
69 static struct pm_qos_object cpu_dma_pm_qos = {
70 .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests, pm_qos_lock),
71 .notifiers = &cpu_dma_lat_notifier,
72 .name = "cpu_dma_latency",
73 .default_value = 2000 * USEC_PER_SEC,
74 .type = PM_QOS_MIN,
77 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
78 static struct pm_qos_object network_lat_pm_qos = {
79 .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests, pm_qos_lock),
80 .notifiers = &network_lat_notifier,
81 .name = "network_latency",
82 .default_value = 2000 * USEC_PER_SEC,
83 .type = PM_QOS_MIN
87 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
88 static struct pm_qos_object network_throughput_pm_qos = {
89 .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock),
90 .notifiers = &network_throughput_notifier,
91 .name = "network_throughput",
92 .default_value = 0,
93 .type = PM_QOS_MAX,
97 static struct pm_qos_object *pm_qos_array[] = {
98 &null_pm_qos,
99 &cpu_dma_pm_qos,
100 &network_lat_pm_qos,
101 &network_throughput_pm_qos
104 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
105 size_t count, loff_t *f_pos);
106 static int pm_qos_power_open(struct inode *inode, struct file *filp);
107 static int pm_qos_power_release(struct inode *inode, struct file *filp);
109 static const struct file_operations pm_qos_power_fops = {
110 .write = pm_qos_power_write,
111 .open = pm_qos_power_open,
112 .release = pm_qos_power_release,
115 /* unlocked internal variant */
116 static inline int pm_qos_get_value(struct pm_qos_object *o)
118 if (plist_head_empty(&o->requests))
119 return o->default_value;
121 switch (o->type) {
122 case PM_QOS_MIN:
123 return plist_last(&o->requests)->prio;
125 case PM_QOS_MAX:
126 return plist_first(&o->requests)->prio;
128 default:
129 /* runtime check for not using enum */
130 BUG();
134 static void update_target(struct pm_qos_object *o, struct plist_node *node,
135 int del, int value)
137 unsigned long flags;
138 int prev_value, curr_value;
140 spin_lock_irqsave(&pm_qos_lock, flags);
141 prev_value = pm_qos_get_value(o);
142 /* PM_QOS_DEFAULT_VALUE is a signal that the value is unchanged */
143 if (value != PM_QOS_DEFAULT_VALUE) {
145 * to change the list, we atomically remove, reinit
146 * with new value and add, then see if the extremal
147 * changed
149 plist_del(node, &o->requests);
150 plist_node_init(node, value);
151 plist_add(node, &o->requests);
152 } else if (del) {
153 plist_del(node, &o->requests);
154 } else {
155 plist_add(node, &o->requests);
157 curr_value = pm_qos_get_value(o);
158 spin_unlock_irqrestore(&pm_qos_lock, flags);
160 if (prev_value != curr_value)
161 blocking_notifier_call_chain(o->notifiers,
162 (unsigned long)curr_value,
163 NULL);
166 static int register_pm_qos_misc(struct pm_qos_object *qos)
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;
172 return misc_register(&qos->pm_qos_power_miscdev);
175 static int find_pm_qos_object_by_minor(int minor)
177 int pm_qos_class;
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;
185 return -1;
189 * pm_qos_request - returns current system wide qos expectation
190 * @pm_qos_class: identification of which qos value is requested
192 * This function returns the current target value in an atomic manner.
194 int pm_qos_request(int pm_qos_class)
196 unsigned long flags;
197 int value;
199 spin_lock_irqsave(&pm_qos_lock, flags);
200 value = pm_qos_get_value(pm_qos_array[pm_qos_class]);
201 spin_unlock_irqrestore(&pm_qos_lock, flags);
203 return value;
205 EXPORT_SYMBOL_GPL(pm_qos_request);
207 int pm_qos_request_active(struct pm_qos_request_list *req)
209 return req->pm_qos_class != 0;
211 EXPORT_SYMBOL_GPL(pm_qos_request_active);
214 * pm_qos_add_request - inserts new qos request into the list
215 * @pm_qos_class: identifies which list of qos request to us
216 * @value: defines the qos request
218 * This function inserts a new entry in the pm_qos_class list of requested qos
219 * performance characteristics. It recomputes the aggregate QoS expectations
220 * for the pm_qos_class of parameters, and returns the pm_qos_request list
221 * element as a handle for use in updating and removal. Call needs to save
222 * this handle for later use.
224 void pm_qos_add_request(struct pm_qos_request_list *dep,
225 int pm_qos_class, s32 value)
227 struct pm_qos_object *o = pm_qos_array[pm_qos_class];
228 int new_value;
230 if (pm_qos_request_active(dep)) {
231 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
232 return;
234 if (value == PM_QOS_DEFAULT_VALUE)
235 new_value = o->default_value;
236 else
237 new_value = value;
238 plist_node_init(&dep->list, new_value);
239 dep->pm_qos_class = pm_qos_class;
240 update_target(o, &dep->list, 0, PM_QOS_DEFAULT_VALUE);
242 EXPORT_SYMBOL_GPL(pm_qos_add_request);
245 * pm_qos_update_request - modifies an existing qos request
246 * @pm_qos_req : handle to list element holding a pm_qos request to use
247 * @value: defines the qos request
249 * Updates an existing qos request for the pm_qos_class of parameters along
250 * with updating the target pm_qos_class value.
252 * Attempts are made to make this code callable on hot code paths.
254 void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
255 s32 new_value)
257 s32 temp;
258 struct pm_qos_object *o;
260 if (!pm_qos_req) /*guard against callers passing in null */
261 return;
263 if (!pm_qos_request_active(pm_qos_req)) {
264 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
265 return;
268 o = pm_qos_array[pm_qos_req->pm_qos_class];
270 if (new_value == PM_QOS_DEFAULT_VALUE)
271 temp = o->default_value;
272 else
273 temp = new_value;
275 if (temp != pm_qos_req->list.prio)
276 update_target(o, &pm_qos_req->list, 0, temp);
278 EXPORT_SYMBOL_GPL(pm_qos_update_request);
281 * pm_qos_remove_request - modifies an existing qos request
282 * @pm_qos_req: handle to request list element
284 * Will remove pm qos request from the list of requests and
285 * recompute the current target value for the pm_qos_class. Call this
286 * on slow code paths.
288 void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req)
290 struct pm_qos_object *o;
292 if (pm_qos_req == NULL)
293 return;
294 /* silent return to keep pcm code cleaner */
296 if (!pm_qos_request_active(pm_qos_req)) {
297 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
298 return;
301 o = pm_qos_array[pm_qos_req->pm_qos_class];
302 update_target(o, &pm_qos_req->list, 1, PM_QOS_DEFAULT_VALUE);
303 memset(pm_qos_req, 0, sizeof(*pm_qos_req));
305 EXPORT_SYMBOL_GPL(pm_qos_remove_request);
308 * pm_qos_add_notifier - sets notification entry for changes to target value
309 * @pm_qos_class: identifies which qos target changes should be notified.
310 * @notifier: notifier block managed by caller.
312 * will register the notifier into a notification chain that gets called
313 * upon changes to the pm_qos_class target value.
315 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
317 int retval;
319 retval = blocking_notifier_chain_register(
320 pm_qos_array[pm_qos_class]->notifiers, notifier);
322 return retval;
324 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
327 * pm_qos_remove_notifier - deletes notification entry from chain.
328 * @pm_qos_class: identifies which qos target changes are notified.
329 * @notifier: notifier block to be removed.
331 * will remove the notifier from the notification chain that gets called
332 * upon changes to the pm_qos_class target value.
334 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
336 int retval;
338 retval = blocking_notifier_chain_unregister(
339 pm_qos_array[pm_qos_class]->notifiers, notifier);
341 return retval;
343 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
345 static int pm_qos_power_open(struct inode *inode, struct file *filp)
347 long pm_qos_class;
349 pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
350 if (pm_qos_class >= 0) {
351 struct pm_qos_request_list *req = kzalloc(GFP_KERNEL, sizeof(*req));
352 if (!req)
353 return -ENOMEM;
355 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
356 filp->private_data = req;
358 if (filp->private_data)
359 return 0;
361 return -EPERM;
364 static int pm_qos_power_release(struct inode *inode, struct file *filp)
366 struct pm_qos_request_list *req;
368 req = filp->private_data;
369 pm_qos_remove_request(req);
370 kfree(req);
372 return 0;
376 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
377 size_t count, loff_t *f_pos)
379 s32 value;
380 int x;
381 char ascii_value[11];
382 struct pm_qos_request_list *pm_qos_req;
384 if (count == sizeof(s32)) {
385 if (copy_from_user(&value, buf, sizeof(s32)))
386 return -EFAULT;
387 } else if (count == 11) { /* len('0x12345678/0') */
388 if (copy_from_user(ascii_value, buf, 11))
389 return -EFAULT;
390 x = sscanf(ascii_value, "%x", &value);
391 if (x != 1)
392 return -EINVAL;
393 pr_debug(KERN_ERR "%s, %d, 0x%x\n", ascii_value, x, value);
394 } else
395 return -EINVAL;
397 pm_qos_req = (struct pm_qos_request_list *)filp->private_data;
398 pm_qos_update_request(pm_qos_req, value);
400 return count;
404 static int __init pm_qos_power_init(void)
406 int ret = 0;
408 ret = register_pm_qos_misc(&cpu_dma_pm_qos);
409 if (ret < 0) {
410 printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
411 return ret;
413 ret = register_pm_qos_misc(&network_lat_pm_qos);
414 if (ret < 0) {
415 printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
416 return ret;
418 ret = register_pm_qos_misc(&network_throughput_pm_qos);
419 if (ret < 0)
420 printk(KERN_ERR
421 "pm_qos_param: network_throughput setup failed\n");
423 return ret;
426 late_initcall(pm_qos_power_init);