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/spinlock.h>
  33 #include <linux/slab.h>
  34 #include <linux/time.h>
  35 #include <linux/fs.h>
  36 #include <linux/device.h>
  37 #include <linux/miscdevice.h>
  38 #include <linux/string.h>
  39 #include <linux/platform_device.h>
  40 #include <linux/init.h>
  41
  42 #include <linux/uaccess.h>
  43
  44 /*
  45  * locking rule: all changes to target_value or requirements or notifiers lists
  46  * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
  47  * held, taken with _irqsave.  One lock to rule them all
  48  */
  49 struct requirement_list {
  50         struct list_head list;
  51         union {
  52                 s32 value;
  53                 s32 usec;
  54                 s32 kbps;
  55         };
  56         char *name;
  57 };
  58
  59 static s32 max_compare(s32 v1, s32 v2);
  60 static s32 min_compare(s32 v1, s32 v2);
  61
  62 struct pm_qos_object {
  63         struct requirement_list requirements;
  64         struct blocking_notifier_head *notifiers;
  65         struct miscdevice pm_qos_power_miscdev;
  66         char *name;
  67         s32 default_value;
  68         s32 target_value;
  69         s32 (*comparitor)(s32, s32);
  70 };
  71
  72 static struct pm_qos_object null_pm_qos;
  73 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
  74 static struct pm_qos_object cpu_dma_pm_qos = {
  75         .requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)},
  76         .notifiers = &cpu_dma_lat_notifier,
  77         .name = "cpu_dma_latency",
  78         .default_value = 2000 * USEC_PER_SEC,
  79         .target_value = 2000 * USEC_PER_SEC,
  80         .comparitor = min_compare
  81 };
  82
  83 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
  84 static struct pm_qos_object network_lat_pm_qos = {
  85         .requirements = {LIST_HEAD_INIT(network_lat_pm_qos.requirements.list)},
  86         .notifiers = &network_lat_notifier,
  87         .name = "network_latency",
  88         .default_value = 2000 * USEC_PER_SEC,
  89         .target_value = 2000 * USEC_PER_SEC,
  90         .comparitor = min_compare
  91 };
  92
  93
  94 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
  95 static struct pm_qos_object network_throughput_pm_qos = {
  96         .requirements =
  97                 {LIST_HEAD_INIT(network_throughput_pm_qos.requirements.list)},
  98         .notifiers = &network_throughput_notifier,
  99         .name = "network_throughput",
 100         .default_value = 0,
 101         .target_value = 0,
 102         .comparitor = max_compare
 103 };
 104
 105
 106 static struct pm_qos_object *pm_qos_array[] = {
 107         &null_pm_qos,
 108         &cpu_dma_pm_qos,
 109         &network_lat_pm_qos,
 110         &network_throughput_pm_qos
 111 };
 112
 113 static DEFINE_SPINLOCK(pm_qos_lock);
 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 target)
 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[target]->default_value;
 147         list_for_each_entry(node,
 148                         &pm_qos_array[target]->requirements.list, list) {
 149                 extreme_value = pm_qos_array[target]->comparitor(
 150                                 extreme_value, node->value);
 151         }
 152         if (pm_qos_array[target]->target_value != extreme_value) {
 153                 call_notifier = 1;
 154                 pm_qos_array[target]->target_value = extreme_value;
 155                 pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
 156                         pm_qos_array[target]->target_value);
 157         }
 158         spin_unlock_irqrestore(&pm_qos_lock, flags);
 159
 160         if (call_notifier)
 161                 blocking_notifier_call_chain(pm_qos_array[target]->notifiers,
 162                         (unsigned long) extreme_value, NULL);
 163 }
 164
 165 static int register_pm_qos_misc(struct pm_qos_object *qos)
 166 {
 167         qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
 168         qos->pm_qos_power_miscdev.name = qos->name;
 169         qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
 170
 171         return misc_register(&qos->pm_qos_power_miscdev);
 172 }
 173
 174 static int find_pm_qos_object_by_minor(int minor)
 175 {
 176         int pm_qos_class;
 177
 178         for (pm_qos_class = 0;
 179                 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
 180                 if (minor ==
 181                         pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
 182                         return pm_qos_class;
 183         }
 184         return -1;
 185 }
 186
 187 /**
 188  * pm_qos_requirement - returns current system wide qos expectation
 189  * @pm_qos_class: identification of which qos value is requested
 190  *
 191  * This function returns the current target value in an atomic manner.
 192  */
 193 int pm_qos_requirement(int pm_qos_class)
 194 {
 195         int ret_val;
 196         unsigned long flags;
 197
 198         spin_lock_irqsave(&pm_qos_lock, flags);
 199         ret_val = pm_qos_array[pm_qos_class]->target_value;
 200         spin_unlock_irqrestore(&pm_qos_lock, flags);
 201
 202         return ret_val;
 203 }
 204 EXPORT_SYMBOL_GPL(pm_qos_requirement);
 205
 206 /**
 207  * pm_qos_add_requirement - inserts new qos request into the list
 208  * @pm_qos_class: identifies which list of qos request to us
 209  * @name: identifies the request
 210  * @value: defines the qos request
 211  *
 212  * This function inserts a new entry in the pm_qos_class list of requested qos
 213  * performance charactoistics.  It recomputes the agregate QoS expectations for
 214  * the pm_qos_class of parrameters.
 215  */
 216 int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value)
 217 {
 218         struct requirement_list *dep;
 219         unsigned long flags;
 220
 221         dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL);
 222         if (dep) {
 223                 if (value == PM_QOS_DEFAULT_VALUE)
 224                         dep->value = pm_qos_array[pm_qos_class]->default_value;
 225                 else
 226                         dep->value = value;
 227                 dep->name = kstrdup(name, GFP_KERNEL);
 228                 if (!dep->name)
 229                         goto cleanup;
 230
 231                 spin_lock_irqsave(&pm_qos_lock, flags);
 232                 list_add(&dep->list,
 233                         &pm_qos_array[pm_qos_class]->requirements.list);
 234                 spin_unlock_irqrestore(&pm_qos_lock, flags);
 235                 update_target(pm_qos_class);
 236
 237                 return 0;
 238         }
 239
 240 cleanup:
 241         kfree(dep);
 242         return -ENOMEM;
 243 }
 244 EXPORT_SYMBOL_GPL(pm_qos_add_requirement);
 245
 246 /**
 247  * pm_qos_update_requirement - modifies an existing qos request
 248  * @pm_qos_class: identifies which list of qos request to us
 249  * @name: identifies the request
 250  * @value: defines the qos request
 251  *
 252  * Updates an existing qos requierement for the pm_qos_class of parameters along
 253  * with updating the target pm_qos_class value.
 254  *
 255  * If the named request isn't in the lest then no change is made.
 256  */
 257 int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value)
 258 {
 259         unsigned long flags;
 260         struct requirement_list *node;
 261         int pending_update = 0;
 262
 263         spin_lock_irqsave(&pm_qos_lock, flags);
 264         list_for_each_entry(node,
 265                 &pm_qos_array[pm_qos_class]->requirements.list, list) {
 266                 if (strcmp(node->name, name) == 0) {
 267                         if (new_value == PM_QOS_DEFAULT_VALUE)
 268                                 node->value =
 269                                 pm_qos_array[pm_qos_class]->default_value;
 270                         else
 271                                 node->value = new_value;
 272                         pending_update = 1;
 273                         break;
 274                 }
 275         }
 276         spin_unlock_irqrestore(&pm_qos_lock, flags);
 277         if (pending_update)
 278                 update_target(pm_qos_class);
 279
 280         return 0;
 281 }
 282 EXPORT_SYMBOL_GPL(pm_qos_update_requirement);
 283
 284 /**
 285  * pm_qos_remove_requirement - modifies an existing qos request
 286  * @pm_qos_class: identifies which list of qos request to us
 287  * @name: identifies the request
 288  *
 289  * Will remove named qos request from pm_qos_class list of parrameters and
 290  * recompute the current target value for the pm_qos_class.
 291  */
 292 void pm_qos_remove_requirement(int pm_qos_class, char *name)
 293 {
 294         unsigned long flags;
 295         struct requirement_list *node;
 296         int pending_update = 0;
 297
 298         spin_lock_irqsave(&pm_qos_lock, flags);
 299         list_for_each_entry(node,
 300                 &pm_qos_array[pm_qos_class]->requirements.list, list) {
 301                 if (strcmp(node->name, name) == 0) {
 302                         kfree(node->name);
 303                         list_del(&node->list);
 304                         kfree(node);
 305                         pending_update = 1;
 306                         break;
 307                 }
 308         }
 309         spin_unlock_irqrestore(&pm_qos_lock, flags);
 310         if (pending_update)
 311                 update_target(pm_qos_class);
 312 }
 313 EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
 314
 315 /**
 316  * pm_qos_add_notifier - sets notification entry for changes to target value
 317  * @pm_qos_class: identifies which qos target changes should be notified.
 318  * @notifier: notifier block managed by caller.
 319  *
 320  * will register the notifier into a notification chain that gets called
 321  * uppon changes to the pm_qos_class target value.
 322  */
 323  int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
 324 {
 325         int retval;
 326
 327         retval = blocking_notifier_chain_register(
 328                         pm_qos_array[pm_qos_class]->notifiers, notifier);
 329
 330         return retval;
 331 }
 332 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
 333
 334 /**
 335  * pm_qos_remove_notifier - deletes notification entry from chain.
 336  * @pm_qos_class: identifies which qos target changes are notified.
 337  * @notifier: notifier block to be removed.
 338  *
 339  * will remove the notifier from the notification chain that gets called
 340  * uppon changes to the pm_qos_class target value.
 341  */
 342 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
 343 {
 344         int retval;
 345
 346         retval = blocking_notifier_chain_unregister(
 347                         pm_qos_array[pm_qos_class]->notifiers, notifier);
 348
 349         return retval;
 350 }
 351 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
 352
 353 #define PID_NAME_LEN sizeof("process_1234567890")
 354 static char name[PID_NAME_LEN];
 355
 356 static int pm_qos_power_open(struct inode *inode, struct file *filp)
 357 {
 358         int ret;
 359         long pm_qos_class;
 360
 361         pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
 362         if (pm_qos_class >= 0) {
 363                 filp->private_data = (void *)pm_qos_class;
 364                 sprintf(name, "process_%d", current->pid);
 365                 ret = pm_qos_add_requirement(pm_qos_class, name,
 366                                         PM_QOS_DEFAULT_VALUE);
 367                 if (ret >= 0)
 368                         return 0;
 369         }
 370
 371         return -EPERM;
 372 }
 373
 374 static int pm_qos_power_release(struct inode *inode, struct file *filp)
 375 {
 376         int pm_qos_class;
 377
 378         pm_qos_class = (long)filp->private_data;
 379         sprintf(name, "process_%d", current->pid);
 380         pm_qos_remove_requirement(pm_qos_class, name);
 381
 382         return 0;
 383 }
 384
 385 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 386                 size_t count, loff_t *f_pos)
 387 {
 388         s32 value;
 389         int pm_qos_class;
 390
 391         pm_qos_class = (long)filp->private_data;
 392         if (count != sizeof(s32))
 393                 return -EINVAL;
 394         if (copy_from_user(&value, buf, sizeof(s32)))
 395                 return -EFAULT;
 396         sprintf(name, "process_%d", current->pid);
 397         pm_qos_update_requirement(pm_qos_class, name, value);
 398
 399         return  sizeof(s32);
 400 }
 401
 402
 403 static int __init pm_qos_power_init(void)
 404 {
 405         int ret = 0;
 406
 407         ret = register_pm_qos_misc(&cpu_dma_pm_qos);
 408         if (ret < 0) {
 409                 printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
 410                 return ret;
 411         }
 412         ret = register_pm_qos_misc(&network_lat_pm_qos);
 413         if (ret < 0) {
 414                 printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
 415                 return ret;
 416         }
 417         ret = register_pm_qos_misc(&network_throughput_pm_qos);
 418         if (ret < 0)
 419                 printk(KERN_ERR
 420                         "pm_qos_param: network_throughput setup failed\n");
 421
 422         return ret;
 423 }
 424
 425 late_initcall(pm_qos_power_init);