Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 | * |
Richard Hughes | bf1db69 | 2008-08-05 13:01:35 -0700 | [diff] [blame] | 27 | * Mark Gross <mgross@linux.intel.com> |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 28 | */ |
| 29 | |
| 30 | #include <linux/pm_qos_params.h> |
| 31 | #include <linux/sched.h> |
Arnd Bergmann | db26e64 | 2008-05-20 19:16:33 +0200 | [diff] [blame] | 32 | #include <linux/smp_lock.h> |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 | /* |
John Kacur | 9d35935 | 2008-09-02 14:36:13 -0700 | [diff] [blame] | 46 | * locking rule: all changes to requirements or notifiers lists |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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; |
John Kacur | 9d35935 | 2008-09-02 14:36:13 -0700 | [diff] [blame] | 69 | atomic_t target_value; |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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, |
John Kacur | 9d35935 | 2008-09-02 14:36:13 -0700 | [diff] [blame] | 80 | .target_value = ATOMIC_INIT(2000 * USEC_PER_SEC), |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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, |
John Kacur | 9d35935 | 2008-09-02 14:36:13 -0700 | [diff] [blame] | 90 | .target_value = ATOMIC_INIT(2000 * USEC_PER_SEC), |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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, |
John Kacur | 9d35935 | 2008-09-02 14:36:13 -0700 | [diff] [blame] | 102 | .target_value = ATOMIC_INIT(0), |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 | } |
John Kacur | 9d35935 | 2008-09-02 14:36:13 -0700 | [diff] [blame] | 153 | if (atomic_read(&pm_qos_array[target]->target_value) != extreme_value) { |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 154 | call_notifier = 1; |
John Kacur | 9d35935 | 2008-09-02 14:36:13 -0700 | [diff] [blame] | 155 | atomic_set(&pm_qos_array[target]->target_value, extreme_value); |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 156 | pr_debug(KERN_ERR "new target for qos %d is %d\n", target, |
John Kacur | 9d35935 | 2008-09-02 14:36:13 -0700 | [diff] [blame] | 157 | atomic_read(&pm_qos_array[target]->target_value)); |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 | { |
John Kacur | 9d35935 | 2008-09-02 14:36:13 -0700 | [diff] [blame] | 196 | return atomic_read(&pm_qos_array[pm_qos_class]->target_value); |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 |
Richard Hughes | bf1db69 | 2008-08-05 13:01:35 -0700 | [diff] [blame] | 207 | * performance characteristics. It recomputes the aggregate QoS expectations |
| 208 | * for the pm_qos_class of parameters. |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 | * |
Richard Hughes | bf1db69 | 2008-08-05 13:01:35 -0700 | [diff] [blame] | 246 | * Updates an existing qos requirement for the pm_qos_class of parameters along |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 247 | * with updating the target pm_qos_class value. |
| 248 | * |
Richard Hughes | bf1db69 | 2008-08-05 13:01:35 -0700 | [diff] [blame] | 249 | * If the named request isn't in the list then no change is made. |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 | * |
Richard Hughes | bf1db69 | 2008-08-05 13:01:35 -0700 | [diff] [blame] | 283 | * Will remove named qos request from pm_qos_class list of parameters and |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 |
Richard Hughes | bf1db69 | 2008-08-05 13:01:35 -0700 | [diff] [blame] | 315 | * upon changes to the pm_qos_class target value. |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 |
Richard Hughes | bf1db69 | 2008-08-05 13:01:35 -0700 | [diff] [blame] | 334 | * upon changes to the pm_qos_class target value. |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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 | |
Arnd Bergmann | db26e64 | 2008-05-20 19:16:33 +0200 | [diff] [blame] | 355 | lock_kernel(); |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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); |
Arnd Bergmann | db26e64 | 2008-05-20 19:16:33 +0200 | [diff] [blame] | 362 | if (ret >= 0) { |
| 363 | unlock_kernel(); |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 364 | return 0; |
Arnd Bergmann | db26e64 | 2008-05-20 19:16:33 +0200 | [diff] [blame] | 365 | } |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 366 | } |
Arnd Bergmann | db26e64 | 2008-05-20 19:16:33 +0200 | [diff] [blame] | 367 | unlock_kernel(); |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 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); |