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
  30 #include <linux/pm_qos_params.h>
  31 #include <linux/sched.h>
  32 #include <linux/smp_lock.h>
  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 /*
  46  * locking rule: all changes to requirements or notifiers lists
  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;
  69         atomic_t target_value;
  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,
  80         .target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
  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,
  90         .target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
  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,
 102         .target_value = ATOMIC_INIT(0),
 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         }
 153         if (atomic_read(&pm_qos_array[target]->target_value) != extreme_value) {
 154                 call_notifier = 1;
 155                 atomic_set(&pm_qos_array[target]->target_value, extreme_value);
 156                 pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
 157                         atomic_read(&pm_qos_array[target]->target_value));
 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 {
 196         return atomic_read(&pm_qos_array[pm_qos_class]->target_value);
 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
 207  * performance characteristics.  It recomputes the aggregate QoS expectations
 208  * for the pm_qos_class of parameters.
 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  *
 246  * Updates an existing qos requirement for the pm_qos_class of parameters along
 247  * with updating the target pm_qos_class value.
 248  *
 249  * If the named request isn't in the list then no change is made.
 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  *
 283  * Will remove named qos request from pm_qos_class list of parameters and
 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
 315  * upon changes to the pm_qos_class target value.
 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
 334  * upon changes to the pm_qos_class target value.
 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
 355         lock_kernel();
 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);
 362                 if (ret >= 0) {
 363                         unlock_kernel();
 364                         return 0;
 365                 }
 366         }
 367         unlock_kernel();
 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);