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Source at commit b05a5adf03613de371c77c3235f7d970d7cd0c71 created 13 years 1 month ago. By Lars-Peter Clausen, NAND: Optimize reading the eec data for the JZ4740 (evil hack) | |
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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 requests |
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 requests, notifiers |
18 | * |
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. |
26 | * |
27 | * Mark Gross <mgross@linux.intel.com> |
28 | */ |
29 | |
30 | /*#define DEBUG*/ |
31 | |
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 | |
44 | #include <linux/uaccess.h> |
45 | |
46 | /* |
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 |
50 | */ |
51 | enum pm_qos_type { |
52 | PM_QOS_MAX, /* return the largest value */ |
53 | PM_QOS_MIN /* return the smallest value */ |
54 | }; |
55 | |
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; |
63 | }; |
64 | |
65 | static DEFINE_SPINLOCK(pm_qos_lock); |
66 | |
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, |
75 | }; |
76 | |
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 |
84 | }; |
85 | |
86 | |
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, |
94 | }; |
95 | |
96 | |
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 |
102 | }; |
103 | |
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 ssize_t pm_qos_power_read(struct file *filp, char __user *buf, |
107 | size_t count, loff_t *f_pos); |
108 | static int pm_qos_power_open(struct inode *inode, struct file *filp); |
109 | static int pm_qos_power_release(struct inode *inode, struct file *filp); |
110 | |
111 | static const struct file_operations pm_qos_power_fops = { |
112 | .write = pm_qos_power_write, |
113 | .read = pm_qos_power_read, |
114 | .open = pm_qos_power_open, |
115 | .release = pm_qos_power_release, |
116 | .llseek = noop_llseek, |
117 | }; |
118 | |
119 | /* unlocked internal variant */ |
120 | static inline int pm_qos_get_value(struct pm_qos_object *o) |
121 | { |
122 | if (plist_head_empty(&o->requests)) |
123 | return o->default_value; |
124 | |
125 | switch (o->type) { |
126 | case PM_QOS_MIN: |
127 | return plist_first(&o->requests)->prio; |
128 | |
129 | case PM_QOS_MAX: |
130 | return plist_last(&o->requests)->prio; |
131 | |
132 | default: |
133 | /* runtime check for not using enum */ |
134 | BUG(); |
135 | } |
136 | } |
137 | |
138 | static void update_target(struct pm_qos_object *o, struct plist_node *node, |
139 | int del, int value) |
140 | { |
141 | unsigned long flags; |
142 | int prev_value, curr_value; |
143 | |
144 | spin_lock_irqsave(&pm_qos_lock, flags); |
145 | prev_value = pm_qos_get_value(o); |
146 | /* PM_QOS_DEFAULT_VALUE is a signal that the value is unchanged */ |
147 | if (value != PM_QOS_DEFAULT_VALUE) { |
148 | /* |
149 | * to change the list, we atomically remove, reinit |
150 | * with new value and add, then see if the extremal |
151 | * changed |
152 | */ |
153 | plist_del(node, &o->requests); |
154 | plist_node_init(node, value); |
155 | plist_add(node, &o->requests); |
156 | } else if (del) { |
157 | plist_del(node, &o->requests); |
158 | } else { |
159 | plist_add(node, &o->requests); |
160 | } |
161 | curr_value = pm_qos_get_value(o); |
162 | spin_unlock_irqrestore(&pm_qos_lock, flags); |
163 | |
164 | if (prev_value != curr_value) |
165 | blocking_notifier_call_chain(o->notifiers, |
166 | (unsigned long)curr_value, |
167 | NULL); |
168 | } |
169 | |
170 | static int register_pm_qos_misc(struct pm_qos_object *qos) |
171 | { |
172 | qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR; |
173 | qos->pm_qos_power_miscdev.name = qos->name; |
174 | qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops; |
175 | |
176 | return misc_register(&qos->pm_qos_power_miscdev); |
177 | } |
178 | |
179 | static int find_pm_qos_object_by_minor(int minor) |
180 | { |
181 | int pm_qos_class; |
182 | |
183 | for (pm_qos_class = 0; |
184 | pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) { |
185 | if (minor == |
186 | pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor) |
187 | return pm_qos_class; |
188 | } |
189 | return -1; |
190 | } |
191 | |
192 | /** |
193 | * pm_qos_request - returns current system wide qos expectation |
194 | * @pm_qos_class: identification of which qos value is requested |
195 | * |
196 | * This function returns the current target value in an atomic manner. |
197 | */ |
198 | int pm_qos_request(int pm_qos_class) |
199 | { |
200 | unsigned long flags; |
201 | int value; |
202 | |
203 | spin_lock_irqsave(&pm_qos_lock, flags); |
204 | value = pm_qos_get_value(pm_qos_array[pm_qos_class]); |
205 | spin_unlock_irqrestore(&pm_qos_lock, flags); |
206 | |
207 | return value; |
208 | } |
209 | EXPORT_SYMBOL_GPL(pm_qos_request); |
210 | |
211 | int pm_qos_request_active(struct pm_qos_request_list *req) |
212 | { |
213 | return req->pm_qos_class != 0; |
214 | } |
215 | EXPORT_SYMBOL_GPL(pm_qos_request_active); |
216 | |
217 | /** |
218 | * pm_qos_add_request - inserts new qos request into the list |
219 | * @dep: pointer to a preallocated handle |
220 | * @pm_qos_class: identifies which list of qos request to use |
221 | * @value: defines the qos request |
222 | * |
223 | * This function inserts a new entry in the pm_qos_class list of requested qos |
224 | * performance characteristics. It recomputes the aggregate QoS expectations |
225 | * for the pm_qos_class of parameters and initializes the pm_qos_request_list |
226 | * handle. Caller needs to save this handle for later use in updates and |
227 | * removal. |
228 | */ |
229 | |
230 | void pm_qos_add_request(struct pm_qos_request_list *dep, |
231 | int pm_qos_class, s32 value) |
232 | { |
233 | struct pm_qos_object *o = pm_qos_array[pm_qos_class]; |
234 | int new_value; |
235 | |
236 | if (pm_qos_request_active(dep)) { |
237 | WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n"); |
238 | return; |
239 | } |
240 | if (value == PM_QOS_DEFAULT_VALUE) |
241 | new_value = o->default_value; |
242 | else |
243 | new_value = value; |
244 | plist_node_init(&dep->list, new_value); |
245 | dep->pm_qos_class = pm_qos_class; |
246 | update_target(o, &dep->list, 0, PM_QOS_DEFAULT_VALUE); |
247 | } |
248 | EXPORT_SYMBOL_GPL(pm_qos_add_request); |
249 | |
250 | /** |
251 | * pm_qos_update_request - modifies an existing qos request |
252 | * @pm_qos_req : handle to list element holding a pm_qos request to use |
253 | * @value: defines the qos request |
254 | * |
255 | * Updates an existing qos request for the pm_qos_class of parameters along |
256 | * with updating the target pm_qos_class value. |
257 | * |
258 | * Attempts are made to make this code callable on hot code paths. |
259 | */ |
260 | void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req, |
261 | s32 new_value) |
262 | { |
263 | s32 temp; |
264 | struct pm_qos_object *o; |
265 | |
266 | if (!pm_qos_req) /*guard against callers passing in null */ |
267 | return; |
268 | |
269 | if (!pm_qos_request_active(pm_qos_req)) { |
270 | WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n"); |
271 | return; |
272 | } |
273 | |
274 | o = pm_qos_array[pm_qos_req->pm_qos_class]; |
275 | |
276 | if (new_value == PM_QOS_DEFAULT_VALUE) |
277 | temp = o->default_value; |
278 | else |
279 | temp = new_value; |
280 | |
281 | if (temp != pm_qos_req->list.prio) |
282 | update_target(o, &pm_qos_req->list, 0, temp); |
283 | } |
284 | EXPORT_SYMBOL_GPL(pm_qos_update_request); |
285 | |
286 | /** |
287 | * pm_qos_remove_request - modifies an existing qos request |
288 | * @pm_qos_req: handle to request list element |
289 | * |
290 | * Will remove pm qos request from the list of requests and |
291 | * recompute the current target value for the pm_qos_class. Call this |
292 | * on slow code paths. |
293 | */ |
294 | void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req) |
295 | { |
296 | struct pm_qos_object *o; |
297 | |
298 | if (pm_qos_req == NULL) |
299 | return; |
300 | /* silent return to keep pcm code cleaner */ |
301 | |
302 | if (!pm_qos_request_active(pm_qos_req)) { |
303 | WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n"); |
304 | return; |
305 | } |
306 | |
307 | o = pm_qos_array[pm_qos_req->pm_qos_class]; |
308 | update_target(o, &pm_qos_req->list, 1, PM_QOS_DEFAULT_VALUE); |
309 | memset(pm_qos_req, 0, sizeof(*pm_qos_req)); |
310 | } |
311 | EXPORT_SYMBOL_GPL(pm_qos_remove_request); |
312 | |
313 | /** |
314 | * pm_qos_add_notifier - sets notification entry for changes to target value |
315 | * @pm_qos_class: identifies which qos target changes should be notified. |
316 | * @notifier: notifier block managed by caller. |
317 | * |
318 | * will register the notifier into a notification chain that gets called |
319 | * upon changes to the pm_qos_class target value. |
320 | */ |
321 | int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier) |
322 | { |
323 | int retval; |
324 | |
325 | retval = blocking_notifier_chain_register( |
326 | pm_qos_array[pm_qos_class]->notifiers, notifier); |
327 | |
328 | return retval; |
329 | } |
330 | EXPORT_SYMBOL_GPL(pm_qos_add_notifier); |
331 | |
332 | /** |
333 | * pm_qos_remove_notifier - deletes notification entry from chain. |
334 | * @pm_qos_class: identifies which qos target changes are notified. |
335 | * @notifier: notifier block to be removed. |
336 | * |
337 | * will remove the notifier from the notification chain that gets called |
338 | * upon changes to the pm_qos_class target value. |
339 | */ |
340 | int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier) |
341 | { |
342 | int retval; |
343 | |
344 | retval = blocking_notifier_chain_unregister( |
345 | pm_qos_array[pm_qos_class]->notifiers, notifier); |
346 | |
347 | return retval; |
348 | } |
349 | EXPORT_SYMBOL_GPL(pm_qos_remove_notifier); |
350 | |
351 | static int pm_qos_power_open(struct inode *inode, struct file *filp) |
352 | { |
353 | long pm_qos_class; |
354 | |
355 | pm_qos_class = find_pm_qos_object_by_minor(iminor(inode)); |
356 | if (pm_qos_class >= 0) { |
357 | struct pm_qos_request_list *req = kzalloc(sizeof(*req), GFP_KERNEL); |
358 | if (!req) |
359 | return -ENOMEM; |
360 | |
361 | pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE); |
362 | filp->private_data = req; |
363 | |
364 | if (filp->private_data) |
365 | return 0; |
366 | } |
367 | return -EPERM; |
368 | } |
369 | |
370 | static int pm_qos_power_release(struct inode *inode, struct file *filp) |
371 | { |
372 | struct pm_qos_request_list *req; |
373 | |
374 | req = filp->private_data; |
375 | pm_qos_remove_request(req); |
376 | kfree(req); |
377 | |
378 | return 0; |
379 | } |
380 | |
381 | |
382 | static ssize_t pm_qos_power_read(struct file *filp, char __user *buf, |
383 | size_t count, loff_t *f_pos) |
384 | { |
385 | s32 value; |
386 | unsigned long flags; |
387 | struct pm_qos_object *o; |
388 | struct pm_qos_request_list *pm_qos_req = filp->private_data;; |
389 | |
390 | if (!pm_qos_req) |
391 | return -EINVAL; |
392 | if (!pm_qos_request_active(pm_qos_req)) |
393 | return -EINVAL; |
394 | |
395 | o = pm_qos_array[pm_qos_req->pm_qos_class]; |
396 | spin_lock_irqsave(&pm_qos_lock, flags); |
397 | value = pm_qos_get_value(o); |
398 | spin_unlock_irqrestore(&pm_qos_lock, flags); |
399 | |
400 | return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32)); |
401 | } |
402 | |
403 | static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, |
404 | size_t count, loff_t *f_pos) |
405 | { |
406 | s32 value; |
407 | int x; |
408 | char ascii_value[11]; |
409 | struct pm_qos_request_list *pm_qos_req; |
410 | |
411 | if (count == sizeof(s32)) { |
412 | if (copy_from_user(&value, buf, sizeof(s32))) |
413 | return -EFAULT; |
414 | } else if (count == 11) { /* len('0x12345678/0') */ |
415 | if (copy_from_user(ascii_value, buf, 11)) |
416 | return -EFAULT; |
417 | if (strlen(ascii_value) != 10) |
418 | return -EINVAL; |
419 | x = sscanf(ascii_value, "%x", &value); |
420 | if (x != 1) |
421 | return -EINVAL; |
422 | pr_debug("%s, %d, 0x%x\n", ascii_value, x, value); |
423 | } else |
424 | return -EINVAL; |
425 | |
426 | pm_qos_req = filp->private_data; |
427 | pm_qos_update_request(pm_qos_req, value); |
428 | |
429 | return count; |
430 | } |
431 | |
432 | |
433 | static int __init pm_qos_power_init(void) |
434 | { |
435 | int ret = 0; |
436 | |
437 | ret = register_pm_qos_misc(&cpu_dma_pm_qos); |
438 | if (ret < 0) { |
439 | printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n"); |
440 | return ret; |
441 | } |
442 | ret = register_pm_qos_misc(&network_lat_pm_qos); |
443 | if (ret < 0) { |
444 | printk(KERN_ERR "pm_qos_param: network_latency setup failed\n"); |
445 | return ret; |
446 | } |
447 | ret = register_pm_qos_misc(&network_throughput_pm_qos); |
448 | if (ret < 0) |
449 | printk(KERN_ERR |
450 | "pm_qos_param: network_throughput setup failed\n"); |
451 | |
452 | return ret; |
453 | } |
454 | |
455 | late_initcall(pm_qos_power_init); |
456 |
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