kernel/pm_qos_params.c

   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 <mgross@linux.intel.com>
  28  *
  29  * Copyright (c) 2009, Code Aurora Forum. All rights reserved.
  30  */
  31
  32 #include <linux/pm_qos_params.h>
  33 #include <linux/sched.h>
  34 #include <linux/smp_lock.h>
  35 #include <linux/spinlock.h>
  36 #include <linux/slab.h>
  37 #include <linux/time.h>
  38 #include <linux/fs.h>
  39 #include <linux/device.h>
  40 #include <linux/miscdevice.h>
  41 #include <linux/string.h>
  42 #include <linux/platform_device.h>
  43 #include <linux/init.h>
  44
  45 #include <linux/uaccess.h>
  46
  47 /*
  48  * locking rule: all changes to requirements 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
  51  */
  52 static s32 max_compare(s32 v1, s32 v2);
  53 static s32 min_compare(s32 v1, s32 v2);
  54
  55 struct pm_qos_power_user {
  56         int pm_qos_class;
  57         char name[sizeof("user_01234567")];
  58 };
  59
  60 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
  61 static struct pm_qos_object cpu_dma_pm_qos = {
  62         .requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)},
  63         .notifiers = &cpu_dma_lat_notifier,
  64         .name = "cpu_dma_latency",
  65         .default_value = 2000 * USEC_PER_SEC,
  66         .target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
  67         .comparitor = min_compare
  68 };
  69
  70 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
  71 static struct pm_qos_object network_lat_pm_qos = {
  72         .requirements = {LIST_HEAD_INIT(network_lat_pm_qos.requirements.list)},
  73         .notifiers = &network_lat_notifier,
  74         .name = "network_latency",
  75         .default_value = 2000 * USEC_PER_SEC,
  76         .target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
  77         .comparitor = min_compare
  78 };
  79
  80
  81 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
  82 static struct pm_qos_object network_throughput_pm_qos = {
  83         .requirements =
  84                 {LIST_HEAD_INIT(network_throughput_pm_qos.requirements.list)},
  85         .notifiers = &network_throughput_notifier,
  86         .name = "network_throughput",
  87         .default_value = 0,
  88         .target_value = ATOMIC_INIT(0),
  89         .comparitor = max_compare
  90 };
  91
  92 static BLOCKING_NOTIFIER_HEAD(system_bus_freq_notifier);
  93 static struct pm_qos_object system_bus_freq_pm_qos = {
  94         .requirements =
  95                 {LIST_HEAD_INIT(system_bus_freq_pm_qos.requirements.list)},
  96         .notifiers = &system_bus_freq_notifier,
  97         .name = "system_bus_freq",
  98         .default_value = 0,
  99         .target_value = ATOMIC_INIT(0),
 100         .comparitor = max_compare
 101 };
 102
 103
 104 static struct pm_qos_object *pm_qos_array[PM_QOS_NUM_CLASSES] = {
 105         [PM_QOS_RESERVED] = NULL,
 106         [PM_QOS_CPU_DMA_LATENCY] = &cpu_dma_pm_qos,
 107         [PM_QOS_NETWORK_LATENCY] = &network_lat_pm_qos,
 108         [PM_QOS_NETWORK_THROUGHPUT] = &network_throughput_pm_qos,
 109         [PM_QOS_SYSTEM_BUS_FREQ] = &system_bus_freq_pm_qos,
 110 };
 111
 112 static DEFINE_SPINLOCK(pm_qos_lock);
 113 static atomic_t pm_qos_user_id = ATOMIC_INIT(0);
 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 pm_qos_class)
 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[pm_qos_class]->default_value;
 147         list_for_each_entry(node,
 148                         &pm_qos_array[pm_qos_class]->requirements.list, list) {
 149                 extreme_value = pm_qos_array[pm_qos_class]->comparitor(
 150                                 extreme_value, node->value);
 151         }
 152         if (atomic_read(&pm_qos_array[pm_qos_class]->target_value) !=
 153                 extreme_value) {
 154                 call_notifier = 1;
 155                 atomic_set(&pm_qos_array[pm_qos_class]->target_value,
 156                         extreme_value);
 157                 pr_debug(KERN_ERR "new target for qos %d is %d\n",
 158                         pm_qos_class, atomic_read(
 159                                 &pm_qos_array[pm_qos_class]->target_value));
 160         }
 161         spin_unlock_irqrestore(&pm_qos_lock, flags);
 162
 163         if (call_notifier)
 164                 blocking_notifier_call_chain(
 165                         pm_qos_array[pm_qos_class]->notifiers,
 166                         (unsigned long) extreme_value, NULL);
 167 }
 168
 169 static int register_pm_qos_misc(struct pm_qos_object *qos)
 170 {
 171         qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
 172         qos->pm_qos_power_miscdev.name = qos->name;
 173         qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
 174
 175         return misc_register(&qos->pm_qos_power_miscdev);
 176 }
 177
 178 static int find_pm_qos_object_by_minor(int minor)
 179 {
 180         int pm_qos_class;
 181
 182         for (pm_qos_class = 0;
 183                 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
 184                 if (!pm_qos_array[pm_qos_class])
 185                         continue;
 186                 if (minor ==
 187                         pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
 188                         return pm_qos_class;
 189         }
 190         return -1;
 191 }
 192
 193 /**
 194  * pm_qos_requirement - returns current system wide qos expectation
 195  * @pm_qos_class: identification of which qos value is requested
 196  *
 197  * This function returns the current target value in an atomic manner.
 198  */
 199 int pm_qos_requirement(int pm_qos_class)
 200 {
 201         return atomic_read(&pm_qos_array[pm_qos_class]->target_value);
 202 }
 203 EXPORT_SYMBOL_GPL(pm_qos_requirement);
 204
 205 /**
 206  * pm_qos_add_requirement - inserts new qos request into the list
 207  * @pm_qos_class: identifies which list of qos request to us
 208  * @name: identifies the request
 209  * @value: defines the qos request
 210  *
 211  * This function inserts a new entry in the pm_qos_class list of requested qos
 212  * performance characteristics.  It recomputes the aggregate QoS expectations
 213  * for the pm_qos_class of parameters.
 214  */
 215 int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value)
 216 {
 217         struct requirement_list *dep;
 218         unsigned long flags;
 219
 220         dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL);
 221         if (dep) {
 222                 if (value == PM_QOS_DEFAULT_VALUE)
 223                         dep->value = pm_qos_array[pm_qos_class]->default_value;
 224                 else
 225                         dep->value = value;
 226                 dep->name = kstrdup(name, GFP_KERNEL);
 227                 if (!dep->name)
 228                         goto cleanup;
 229
 230                 spin_lock_irqsave(&pm_qos_lock, flags);
 231                 list_add(&dep->list,
 232                         &pm_qos_array[pm_qos_class]->requirements.list);
 233                 spin_unlock_irqrestore(&pm_qos_lock, flags);
 234                 update_target(pm_qos_class);
 235
 236                 return 0;
 237         }
 238
 239 cleanup:
 240         kfree(dep);
 241         return -ENOMEM;
 242 }
 243 EXPORT_SYMBOL_GPL(pm_qos_add_requirement);
 244
 245 /**
 246  * pm_qos_update_requirement - modifies an existing qos request
 247  * @pm_qos_class: identifies which list of qos request to us
 248  * @name: identifies the request
 249  * @value: defines the qos request
 250  *
 251  * Updates an existing qos requirement for the pm_qos_class of parameters along
 252  * with updating the target pm_qos_class value.
 253  *
 254  * If the named request isn't in the list then no change is made.
 255  */
 256 int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value)
 257 {
 258         unsigned long flags;
 259         struct requirement_list *node;
 260         int pending_update = 0;
 261
 262         spin_lock_irqsave(&pm_qos_lock, flags);
 263         list_for_each_entry(node,
 264                 &pm_qos_array[pm_qos_class]->requirements.list, list) {
 265                 if (strcmp(node->name, name) == 0) {
 266                         if (new_value == PM_QOS_DEFAULT_VALUE)
 267                                 node->value =
 268                                 pm_qos_array[pm_qos_class]->default_value;
 269                         else
 270                                 node->value = new_value;
 271                         pending_update = 1;
 272                         break;
 273                 }
 274         }
 275         spin_unlock_irqrestore(&pm_qos_lock, flags);
 276         if (pending_update)
 277                 update_target(pm_qos_class);
 278
 279         return 0;
 280 }
 281 EXPORT_SYMBOL_GPL(pm_qos_update_requirement);
 282
 283 /**
 284  * pm_qos_remove_requirement - modifies an existing qos request
 285  * @pm_qos_class: identifies which list of qos request to us
 286  * @name: identifies the request
 287  *
 288  * Will remove named qos request from pm_qos_class list of parameters and
 289  * recompute the current target value for the pm_qos_class.
 290  */
 291 void pm_qos_remove_requirement(int pm_qos_class, char *name)
 292 {
 293         unsigned long flags;
 294         struct requirement_list *node;
 295         int pending_update = 0;
 296
 297         spin_lock_irqsave(&pm_qos_lock, flags);
 298         list_for_each_entry(node,
 299                 &pm_qos_array[pm_qos_class]->requirements.list, list) {
 300                 if (strcmp(node->name, name) == 0) {
 301                         kfree(node->name);
 302                         list_del(&node->list);
 303                         kfree(node);
 304                         pending_update = 1;
 305                         break;
 306                 }
 307         }
 308         spin_unlock_irqrestore(&pm_qos_lock, flags);
 309         if (pending_update)
 310                 update_target(pm_qos_class);
 311 }
 312 EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
 313
 314 /**
 315  * pm_qos_add_notifier - sets notification entry for changes to target value
 316  * @pm_qos_class: identifies which qos target changes should be notified.
 317  * @notifier: notifier block managed by caller.
 318  *
 319  * will register the notifier into a notification chain that gets called
 320  * upon changes to the pm_qos_class target value.
 321  */
 322 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
 323 {
 324         int retval;
 325
 326         retval = blocking_notifier_chain_register(
 327                         pm_qos_array[pm_qos_class]->notifiers, notifier);
 328
 329         return retval;
 330 }
 331 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
 332
 333 /**
 334  * pm_qos_remove_notifier - deletes notification entry from chain.
 335  * @pm_qos_class: identifies which qos target changes are notified.
 336  * @notifier: notifier block to be removed.
 337  *
 338  * will remove the notifier from the notification chain that gets called
 339  * upon changes to the pm_qos_class target value.
 340  */
 341 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
 342 {
 343         int retval;
 344
 345         retval = blocking_notifier_chain_unregister(
 346                         pm_qos_array[pm_qos_class]->notifiers, notifier);
 347
 348         return retval;
 349 }
 350 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
 351
 352
 353 static int pm_qos_power_open(struct inode *inode, struct file *filp)
 354 {
 355         int ret;
 356         int pm_qos_class;
 357         struct pm_qos_power_user *usr;
 358
 359         usr = kzalloc(sizeof(struct pm_qos_power_user), GFP_KERNEL);
 360         if (!usr)
 361                 return -ENOMEM;
 362
 363         lock_kernel();
 364         pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
 365         if (pm_qos_class < 0) {
 366                 unlock_kernel();
 367                 kfree(usr);
 368                 return -EPERM;
 369         }
 370
 371         usr->pm_qos_class = pm_qos_class;
 372         snprintf(usr->name, sizeof(usr->name),
 373                 "user_%08x", (unsigned)atomic_inc_return(&pm_qos_user_id));
 374
 375         ret = pm_qos_add_requirement(usr->pm_qos_class, usr->name,
 376                         PM_QOS_DEFAULT_VALUE);
 377         unlock_kernel();
 378
 379         if (ret < 0) {
 380                 kfree(usr);
 381                 return ret;
 382         }
 383
 384         filp->private_data = usr;
 385         return 0;
 386 }
 387
 388 static int pm_qos_power_release(struct inode *inode, struct file *filp)
 389 {
 390         struct pm_qos_power_user *usr;
 391
 392         usr = (struct pm_qos_power_user *)filp->private_data;
 393         pm_qos_remove_requirement(usr->pm_qos_class, usr->name);
 394
 395         filp->private_data = NULL;
 396         kfree(usr);
 397         return 0;
 398 }
 399
 400 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 401                 size_t count, loff_t *f_pos)
 402 {
 403         struct pm_qos_power_user *usr;
 404         s32 value;
 405
 406         usr = (struct pm_qos_power_user *)filp->private_data;
 407
 408         if (count != sizeof(s32))
 409                 return -EINVAL;
 410
 411         if (get_user(value, (s32 *)buf))
 412                 return -EFAULT;
 413
 414         pm_qos_update_requirement(usr->pm_qos_class, usr->name, value);
 415         return  sizeof(s32);
 416 }
 417
 418
 419 static int __init pm_qos_power_init(void)
 420 {
 421         int ret = 0;
 422
 423         ret = register_pm_qos_misc(&cpu_dma_pm_qos);
 424         if (ret < 0) {
 425                 printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
 426                 return ret;
 427         }
 428         ret = register_pm_qos_misc(&network_lat_pm_qos);
 429         if (ret < 0) {
 430                 printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
 431                 return ret;
 432         }
 433         ret = register_pm_qos_misc(&network_throughput_pm_qos);
 434         if (ret < 0) {
 435                 printk(KERN_ERR
 436                         "pm_qos_param: network_throughput setup failed\n");
 437                 return ret;
 438         }
 439         ret = register_pm_qos_misc(&system_bus_freq_pm_qos);
 440         if (ret < 0)
 441                 printk(KERN_ERR
 442                         "pm_qos_param: system_bus_freq setup failed\n");
 443
 444         return ret;
 445 }
 446
 447 late_initcall(pm_qos_power_init);