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 target_value or 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         s32 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 = 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 = 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 = 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 (pm_qos_array[target]->target_value != extreme_value) {
 154                 call_notifier = 1;
 155                 pm_qos_array[target]->target_value = extreme_value;
 156                 pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
 157                         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         int ret_val;
 197         unsigned long flags;
 198
 199         spin_lock_irqsave(&pm_qos_lock, flags);
 200         ret_val = pm_qos_array[pm_qos_class]->target_value;
 201         spin_unlock_irqrestore(&pm_qos_lock, flags);
 202
 203         return ret_val;
 204 }
 205 EXPORT_SYMBOL_GPL(pm_qos_requirement);
 206
 207 /**
 208  * pm_qos_add_requirement - inserts new qos request into the list
 209  * @pm_qos_class: identifies which list of qos request to us
 210  * @name: identifies the request
 211  * @value: defines the qos request
 212  *
 213  * This function inserts a new entry in the pm_qos_class list of requested qos
 214  * performance characteristics.  It recomputes the aggregate QoS expectations
 215  * for the pm_qos_class of parameters.
 216  */
 217 int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value)
 218 {
 219         struct requirement_list *dep;
 220         unsigned long flags;
 221
 222         dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL);
 223         if (dep) {
 224                 if (value == PM_QOS_DEFAULT_VALUE)
 225                         dep->value = pm_qos_array[pm_qos_class]->default_value;
 226                 else
 227                         dep->value = value;
 228                 dep->name = kstrdup(name, GFP_KERNEL);
 229                 if (!dep->name)
 230                         goto cleanup;
 231
 232                 spin_lock_irqsave(&pm_qos_lock, flags);
 233                 list_add(&dep->list,
 234                         &pm_qos_array[pm_qos_class]->requirements.list);
 235                 spin_unlock_irqrestore(&pm_qos_lock, flags);
 236                 update_target(pm_qos_class);
 237
 238                 return 0;
 239         }
 240
 241 cleanup:
 242         kfree(dep);
 243         return -ENOMEM;
 244 }
 245 EXPORT_SYMBOL_GPL(pm_qos_add_requirement);
 246
 247 /**
 248  * pm_qos_update_requirement - modifies an existing qos request
 249  * @pm_qos_class: identifies which list of qos request to us
 250  * @name: identifies the request
 251  * @value: defines the qos request
 252  *
 253  * Updates an existing qos requirement for the pm_qos_class of parameters along
 254  * with updating the target pm_qos_class value.
 255  *
 256  * If the named request isn't in the list then no change is made.
 257  */
 258 int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value)
 259 {
 260         unsigned long flags;
 261         struct requirement_list *node;
 262         int pending_update = 0;
 263
 264         spin_lock_irqsave(&pm_qos_lock, flags);
 265         list_for_each_entry(node,
 266                 &pm_qos_array[pm_qos_class]->requirements.list, list) {
 267                 if (strcmp(node->name, name) == 0) {
 268                         if (new_value == PM_QOS_DEFAULT_VALUE)
 269                                 node->value =
 270                                 pm_qos_array[pm_qos_class]->default_value;
 271                         else
 272                                 node->value = new_value;
 273                         pending_update = 1;
 274                         break;
 275                 }
 276         }
 277         spin_unlock_irqrestore(&pm_qos_lock, flags);
 278         if (pending_update)
 279                 update_target(pm_qos_class);
 280
 281         return 0;
 282 }
 283 EXPORT_SYMBOL_GPL(pm_qos_update_requirement);
 284
 285 /**
 286  * pm_qos_remove_requirement - modifies an existing qos request
 287  * @pm_qos_class: identifies which list of qos request to us
 288  * @name: identifies the request
 289  *
 290  * Will remove named qos request from pm_qos_class list of parameters and
 291  * recompute the current target value for the pm_qos_class.
 292  */
 293 void pm_qos_remove_requirement(int pm_qos_class, char *name)
 294 {
 295         unsigned long flags;
 296         struct requirement_list *node;
 297         int pending_update = 0;
 298
 299         spin_lock_irqsave(&pm_qos_lock, flags);
 300         list_for_each_entry(node,
 301                 &pm_qos_array[pm_qos_class]->requirements.list, list) {
 302                 if (strcmp(node->name, name) == 0) {
 303                         kfree(node->name);
 304                         list_del(&node->list);
 305                         kfree(node);
 306                         pending_update = 1;
 307                         break;
 308                 }
 309         }
 310         spin_unlock_irqrestore(&pm_qos_lock, flags);
 311         if (pending_update)
 312                 update_target(pm_qos_class);
 313 }
 314 EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
 315
 316 /**
 317  * pm_qos_add_notifier - sets notification entry for changes to target value
 318  * @pm_qos_class: identifies which qos target changes should be notified.
 319  * @notifier: notifier block managed by caller.
 320  *
 321  * will register the notifier into a notification chain that gets called
 322  * upon changes to the pm_qos_class target value.
 323  */
 324  int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
 325 {
 326         int retval;
 327
 328         retval = blocking_notifier_chain_register(
 329                         pm_qos_array[pm_qos_class]->notifiers, notifier);
 330
 331         return retval;
 332 }
 333 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
 334
 335 /**
 336  * pm_qos_remove_notifier - deletes notification entry from chain.
 337  * @pm_qos_class: identifies which qos target changes are notified.
 338  * @notifier: notifier block to be removed.
 339  *
 340  * will remove the notifier from the notification chain that gets called
 341  * upon changes to the pm_qos_class target value.
 342  */
 343 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
 344 {
 345         int retval;
 346
 347         retval = blocking_notifier_chain_unregister(
 348                         pm_qos_array[pm_qos_class]->notifiers, notifier);
 349
 350         return retval;
 351 }
 352 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
 353
 354 #define PID_NAME_LEN sizeof("process_1234567890")
 355 static char name[PID_NAME_LEN];
 356
 357 static int pm_qos_power_open(struct inode *inode, struct file *filp)
 358 {
 359         int ret;
 360         long pm_qos_class;
 361
 362         lock_kernel();
 363         pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
 364         if (pm_qos_class >= 0) {
 365                 filp->private_data = (void *)pm_qos_class;
 366                 sprintf(name, "process_%d", current->pid);
 367                 ret = pm_qos_add_requirement(pm_qos_class, name,
 368                                         PM_QOS_DEFAULT_VALUE);
 369                 if (ret >= 0) {
 370                         unlock_kernel();
 371                         return 0;
 372                 }
 373         }
 374         unlock_kernel();
 375
 376         return -EPERM;
 377 }
 378
 379 static int pm_qos_power_release(struct inode *inode, struct file *filp)
 380 {
 381         int pm_qos_class;
 382
 383         pm_qos_class = (long)filp->private_data;
 384         sprintf(name, "process_%d", current->pid);
 385         pm_qos_remove_requirement(pm_qos_class, name);
 386
 387         return 0;
 388 }
 389
 390 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 391                 size_t count, loff_t *f_pos)
 392 {
 393         s32 value;
 394         int pm_qos_class;
 395
 396         pm_qos_class = (long)filp->private_data;
 397         if (count != sizeof(s32))
 398                 return -EINVAL;
 399         if (copy_from_user(&value, buf, sizeof(s32)))
 400                 return -EFAULT;
 401         sprintf(name, "process_%d", current->pid);
 402         pm_qos_update_requirement(pm_qos_class, name, value);
 403
 404         return  sizeof(s32);
 405 }
 406
 407
 408 static int __init pm_qos_power_init(void)
 409 {
 410         int ret = 0;
 411
 412         ret = register_pm_qos_misc(&cpu_dma_pm_qos);
 413         if (ret < 0) {
 414                 printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
 415                 return ret;
 416         }
 417         ret = register_pm_qos_misc(&network_lat_pm_qos);
 418         if (ret < 0) {
 419                 printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
 420                 return ret;
 421         }
 422         ret = register_pm_qos_misc(&network_throughput_pm_qos);
 423         if (ret < 0)
 424                 printk(KERN_ERR
 425                         "pm_qos_param: network_throughput setup failed\n");
 426
 427         return ret;
 428 }
 429
 430 late_initcall(pm_qos_power_init);