LCOV - code coverage report
Current view: top level - kernel/power - qos.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 2 131 1.5 %
Date: 2014-02-18 Functions: 1 18 5.6 %
Branches: 0 79 0.0 %

           Branch data     Line data    Source code
       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 requests
       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 requests, notifiers
      18                 :            :  *
      19                 :            :  * User mode requests 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                 :            :  * request is removed and a new qos target is computed.  This way when the
      24                 :            :  * request 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                 :            : /*#define DEBUG*/
      31                 :            : 
      32                 :            : #include <linux/pm_qos.h>
      33                 :            : #include <linux/sched.h>
      34                 :            : #include <linux/spinlock.h>
      35                 :            : #include <linux/slab.h>
      36                 :            : #include <linux/time.h>
      37                 :            : #include <linux/fs.h>
      38                 :            : #include <linux/device.h>
      39                 :            : #include <linux/miscdevice.h>
      40                 :            : #include <linux/string.h>
      41                 :            : #include <linux/platform_device.h>
      42                 :            : #include <linux/init.h>
      43                 :            : #include <linux/kernel.h>
      44                 :            : 
      45                 :            : #include <linux/uaccess.h>
      46                 :            : #include <linux/export.h>
      47                 :            : #include <trace/events/power.h>
      48                 :            : 
      49                 :            : /*
      50                 :            :  * locking rule: all changes to constraints or notifiers lists
      51                 :            :  * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
      52                 :            :  * held, taken with _irqsave.  One lock to rule them all
      53                 :            :  */
      54                 :            : struct pm_qos_object {
      55                 :            :         struct pm_qos_constraints *constraints;
      56                 :            :         struct miscdevice pm_qos_power_miscdev;
      57                 :            :         char *name;
      58                 :            : };
      59                 :            : 
      60                 :            : static DEFINE_SPINLOCK(pm_qos_lock);
      61                 :            : 
      62                 :            : static struct pm_qos_object null_pm_qos;
      63                 :            : 
      64                 :            : static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
      65                 :            : static struct pm_qos_constraints cpu_dma_constraints = {
      66                 :            :         .list = PLIST_HEAD_INIT(cpu_dma_constraints.list),
      67                 :            :         .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
      68                 :            :         .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
      69                 :            :         .type = PM_QOS_MIN,
      70                 :            :         .notifiers = &cpu_dma_lat_notifier,
      71                 :            : };
      72                 :            : static struct pm_qos_object cpu_dma_pm_qos = {
      73                 :            :         .constraints = &cpu_dma_constraints,
      74                 :            :         .name = "cpu_dma_latency",
      75                 :            : };
      76                 :            : 
      77                 :            : static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
      78                 :            : static struct pm_qos_constraints network_lat_constraints = {
      79                 :            :         .list = PLIST_HEAD_INIT(network_lat_constraints.list),
      80                 :            :         .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
      81                 :            :         .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
      82                 :            :         .type = PM_QOS_MIN,
      83                 :            :         .notifiers = &network_lat_notifier,
      84                 :            : };
      85                 :            : static struct pm_qos_object network_lat_pm_qos = {
      86                 :            :         .constraints = &network_lat_constraints,
      87                 :            :         .name = "network_latency",
      88                 :            : };
      89                 :            : 
      90                 :            : 
      91                 :            : static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
      92                 :            : static struct pm_qos_constraints network_tput_constraints = {
      93                 :            :         .list = PLIST_HEAD_INIT(network_tput_constraints.list),
      94                 :            :         .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
      95                 :            :         .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
      96                 :            :         .type = PM_QOS_MAX,
      97                 :            :         .notifiers = &network_throughput_notifier,
      98                 :            : };
      99                 :            : static struct pm_qos_object network_throughput_pm_qos = {
     100                 :            :         .constraints = &network_tput_constraints,
     101                 :            :         .name = "network_throughput",
     102                 :            : };
     103                 :            : 
     104                 :            : 
     105                 :            : static struct pm_qos_object *pm_qos_array[] = {
     106                 :            :         &null_pm_qos,
     107                 :            :         &cpu_dma_pm_qos,
     108                 :            :         &network_lat_pm_qos,
     109                 :            :         &network_throughput_pm_qos
     110                 :            : };
     111                 :            : 
     112                 :            : static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
     113                 :            :                 size_t count, loff_t *f_pos);
     114                 :            : static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
     115                 :            :                 size_t count, loff_t *f_pos);
     116                 :            : static int pm_qos_power_open(struct inode *inode, struct file *filp);
     117                 :            : static int pm_qos_power_release(struct inode *inode, struct file *filp);
     118                 :            : 
     119                 :            : static const struct file_operations pm_qos_power_fops = {
     120                 :            :         .write = pm_qos_power_write,
     121                 :            :         .read = pm_qos_power_read,
     122                 :            :         .open = pm_qos_power_open,
     123                 :            :         .release = pm_qos_power_release,
     124                 :            :         .llseek = noop_llseek,
     125                 :            : };
     126                 :            : 
     127                 :            : /* unlocked internal variant */
     128                 :            : static inline int pm_qos_get_value(struct pm_qos_constraints *c)
     129                 :            : {
     130   [ #  #  #  # ]:          0 :         if (plist_head_empty(&c->list))
                 [ #  # ]
     131                 :          0 :                 return c->default_value;
     132                 :            : 
     133      [ #  #  # ]:          0 :         switch (c->type) {
              [ #  #  # ]
              [ #  #  # ]
     134                 :            :         case PM_QOS_MIN:
     135                 :          0 :                 return plist_first(&c->list)->prio;
     136                 :            : 
     137                 :            :         case PM_QOS_MAX:
     138                 :          0 :                 return plist_last(&c->list)->prio;
     139                 :            : 
     140                 :            :         default:
     141                 :            :                 /* runtime check for not using enum */
     142                 :          0 :                 BUG();
     143                 :            :                 return PM_QOS_DEFAULT_VALUE;
     144                 :            :         }
     145                 :            : }
     146                 :            : 
     147                 :          0 : s32 pm_qos_read_value(struct pm_qos_constraints *c)
     148                 :            : {
     149                 :    5637180 :         return c->target_value;
     150                 :            : }
     151                 :            : 
     152                 :            : static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
     153                 :            : {
     154                 :          0 :         c->target_value = value;
     155                 :            : }
     156                 :            : 
     157                 :            : /**
     158                 :            :  * pm_qos_update_target - manages the constraints list and calls the notifiers
     159                 :            :  *  if needed
     160                 :            :  * @c: constraints data struct
     161                 :            :  * @node: request to add to the list, to update or to remove
     162                 :            :  * @action: action to take on the constraints list
     163                 :            :  * @value: value of the request to add or update
     164                 :            :  *
     165                 :            :  * This function returns 1 if the aggregated constraint value has changed, 0
     166                 :            :  *  otherwise.
     167                 :            :  */
     168                 :          0 : int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
     169                 :            :                          enum pm_qos_req_action action, int value)
     170                 :            : {
     171                 :            :         unsigned long flags;
     172                 :            :         int prev_value, curr_value, new_value;
     173                 :            : 
     174                 :          0 :         spin_lock_irqsave(&pm_qos_lock, flags);
     175                 :            :         prev_value = pm_qos_get_value(c);
     176         [ #  # ]:          0 :         if (value == PM_QOS_DEFAULT_VALUE)
     177                 :          0 :                 new_value = c->default_value;
     178                 :            :         else
     179                 :            :                 new_value = value;
     180                 :            : 
     181   [ #  #  #  # ]:          0 :         switch (action) {
     182                 :            :         case PM_QOS_REMOVE_REQ:
     183                 :          0 :                 plist_del(node, &c->list);
     184                 :          0 :                 break;
     185                 :            :         case PM_QOS_UPDATE_REQ:
     186                 :            :                 /*
     187                 :            :                  * to change the list, we atomically remove, reinit
     188                 :            :                  * with new value and add, then see if the extremal
     189                 :            :                  * changed
     190                 :            :                  */
     191                 :          0 :                 plist_del(node, &c->list);
     192                 :            :         case PM_QOS_ADD_REQ:
     193                 :            :                 plist_node_init(node, new_value);
     194                 :          0 :                 plist_add(node, &c->list);
     195                 :          0 :                 break;
     196                 :            :         default:
     197                 :            :                 /* no action */
     198                 :            :                 ;
     199                 :            :         }
     200                 :            : 
     201                 :            :         curr_value = pm_qos_get_value(c);
     202                 :            :         pm_qos_set_value(c, curr_value);
     203                 :            : 
     204                 :            :         spin_unlock_irqrestore(&pm_qos_lock, flags);
     205                 :            : 
     206                 :            :         trace_pm_qos_update_target(action, prev_value, curr_value);
     207         [ #  # ]:          0 :         if (prev_value != curr_value) {
     208                 :          0 :                 blocking_notifier_call_chain(c->notifiers,
     209                 :            :                                              (unsigned long)curr_value,
     210                 :            :                                              NULL);
     211                 :          0 :                 return 1;
     212                 :            :         } else {
     213                 :            :                 return 0;
     214                 :            :         }
     215                 :            : }
     216                 :            : 
     217                 :            : /**
     218                 :            :  * pm_qos_flags_remove_req - Remove device PM QoS flags request.
     219                 :            :  * @pqf: Device PM QoS flags set to remove the request from.
     220                 :            :  * @req: Request to remove from the set.
     221                 :            :  */
     222                 :            : static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
     223                 :            :                                     struct pm_qos_flags_request *req)
     224                 :            : {
     225                 :            :         s32 val = 0;
     226                 :            : 
     227                 :            :         list_del(&req->node);
     228 [ #  # ][ #  # ]:          0 :         list_for_each_entry(req, &pqf->list, node)
     229                 :          0 :                 val |= req->flags;
     230                 :            : 
     231                 :          0 :         pqf->effective_flags = val;
     232                 :            : }
     233                 :            : 
     234                 :            : /**
     235                 :            :  * pm_qos_update_flags - Update a set of PM QoS flags.
     236                 :            :  * @pqf: Set of flags to update.
     237                 :            :  * @req: Request to add to the set, to modify, or to remove from the set.
     238                 :            :  * @action: Action to take on the set.
     239                 :            :  * @val: Value of the request to add or modify.
     240                 :            :  *
     241                 :            :  * Update the given set of PM QoS flags and call notifiers if the aggregate
     242                 :            :  * value has changed.  Returns 1 if the aggregate constraint value has changed,
     243                 :            :  * 0 otherwise.
     244                 :            :  */
     245                 :          0 : bool pm_qos_update_flags(struct pm_qos_flags *pqf,
     246                 :            :                          struct pm_qos_flags_request *req,
     247                 :            :                          enum pm_qos_req_action action, s32 val)
     248                 :            : {
     249                 :            :         unsigned long irqflags;
     250                 :            :         s32 prev_value, curr_value;
     251                 :            : 
     252                 :          0 :         spin_lock_irqsave(&pm_qos_lock, irqflags);
     253                 :            : 
     254         [ #  # ]:          0 :         prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
     255                 :            : 
     256   [ #  #  #  # ]:          0 :         switch (action) {
     257                 :            :         case PM_QOS_REMOVE_REQ:
     258                 :            :                 pm_qos_flags_remove_req(pqf, req);
     259                 :            :                 break;
     260                 :            :         case PM_QOS_UPDATE_REQ:
     261                 :            :                 pm_qos_flags_remove_req(pqf, req);
     262                 :            :         case PM_QOS_ADD_REQ:
     263                 :          0 :                 req->flags = val;
     264                 :          0 :                 INIT_LIST_HEAD(&req->node);
     265                 :            :                 list_add_tail(&req->node, &pqf->list);
     266                 :          0 :                 pqf->effective_flags |= val;
     267                 :          0 :                 break;
     268                 :            :         default:
     269                 :            :                 /* no action */
     270                 :            :                 ;
     271                 :            :         }
     272                 :            : 
     273         [ #  # ]:          0 :         curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
     274                 :            : 
     275                 :            :         spin_unlock_irqrestore(&pm_qos_lock, irqflags);
     276                 :            : 
     277                 :            :         trace_pm_qos_update_flags(action, prev_value, curr_value);
     278                 :          0 :         return prev_value != curr_value;
     279                 :            : }
     280                 :            : 
     281                 :            : /**
     282                 :            :  * pm_qos_request - returns current system wide qos expectation
     283                 :            :  * @pm_qos_class: identification of which qos value is requested
     284                 :            :  *
     285                 :            :  * This function returns the current target value.
     286                 :            :  */
     287                 :          0 : int pm_qos_request(int pm_qos_class)
     288                 :            : {
     289                 :   11274360 :         return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
     290                 :            : }
     291                 :            : EXPORT_SYMBOL_GPL(pm_qos_request);
     292                 :            : 
     293                 :          0 : int pm_qos_request_active(struct pm_qos_request *req)
     294                 :            : {
     295                 :          0 :         return req->pm_qos_class != 0;
     296                 :            : }
     297                 :            : EXPORT_SYMBOL_GPL(pm_qos_request_active);
     298                 :            : 
     299                 :          0 : static void __pm_qos_update_request(struct pm_qos_request *req,
     300                 :            :                            s32 new_value)
     301                 :            : {
     302                 :          0 :         trace_pm_qos_update_request(req->pm_qos_class, new_value);
     303                 :            : 
     304         [ #  # ]:          0 :         if (new_value != req->node.prio)
     305                 :          0 :                 pm_qos_update_target(
     306                 :          0 :                         pm_qos_array[req->pm_qos_class]->constraints,
     307                 :            :                         &req->node, PM_QOS_UPDATE_REQ, new_value);
     308                 :          0 : }
     309                 :            : 
     310                 :            : /**
     311                 :            :  * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
     312                 :            :  * @work: work struct for the delayed work (timeout)
     313                 :            :  *
     314                 :            :  * This cancels the timeout request by falling back to the default at timeout.
     315                 :            :  */
     316                 :          0 : static void pm_qos_work_fn(struct work_struct *work)
     317                 :            : {
     318                 :          0 :         struct pm_qos_request *req = container_of(to_delayed_work(work),
     319                 :            :                                                   struct pm_qos_request,
     320                 :            :                                                   work);
     321                 :            : 
     322                 :          0 :         __pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
     323                 :          0 : }
     324                 :            : 
     325                 :            : /**
     326                 :            :  * pm_qos_add_request - inserts new qos request into the list
     327                 :            :  * @req: pointer to a preallocated handle
     328                 :            :  * @pm_qos_class: identifies which list of qos request to use
     329                 :            :  * @value: defines the qos request
     330                 :            :  *
     331                 :            :  * This function inserts a new entry in the pm_qos_class list of requested qos
     332                 :            :  * performance characteristics.  It recomputes the aggregate QoS expectations
     333                 :            :  * for the pm_qos_class of parameters and initializes the pm_qos_request
     334                 :            :  * handle.  Caller needs to save this handle for later use in updates and
     335                 :            :  * removal.
     336                 :            :  */
     337                 :            : 
     338                 :          0 : void pm_qos_add_request(struct pm_qos_request *req,
     339                 :            :                         int pm_qos_class, s32 value)
     340                 :            : {
     341         [ #  # ]:          0 :         if (!req) /*guard against callers passing in null */
     342                 :            :                 return;
     343                 :            : 
     344         [ #  # ]:          0 :         if (pm_qos_request_active(req)) {
     345                 :          0 :                 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
     346                 :          0 :                 return;
     347                 :            :         }
     348                 :          0 :         req->pm_qos_class = pm_qos_class;
     349                 :          0 :         INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
     350                 :            :         trace_pm_qos_add_request(pm_qos_class, value);
     351                 :          0 :         pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
     352                 :            :                              &req->node, PM_QOS_ADD_REQ, value);
     353                 :            : }
     354                 :            : EXPORT_SYMBOL_GPL(pm_qos_add_request);
     355                 :            : 
     356                 :            : /**
     357                 :            :  * pm_qos_update_request - modifies an existing qos request
     358                 :            :  * @req : handle to list element holding a pm_qos request to use
     359                 :            :  * @value: defines the qos request
     360                 :            :  *
     361                 :            :  * Updates an existing qos request for the pm_qos_class of parameters along
     362                 :            :  * with updating the target pm_qos_class value.
     363                 :            :  *
     364                 :            :  * Attempts are made to make this code callable on hot code paths.
     365                 :            :  */
     366                 :          0 : void pm_qos_update_request(struct pm_qos_request *req,
     367                 :            :                            s32 new_value)
     368                 :            : {
     369         [ #  # ]:          0 :         if (!req) /*guard against callers passing in null */
     370                 :            :                 return;
     371                 :            : 
     372         [ #  # ]:          0 :         if (!pm_qos_request_active(req)) {
     373                 :          0 :                 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
     374                 :          0 :                 return;
     375                 :            :         }
     376                 :            : 
     377                 :          0 :         cancel_delayed_work_sync(&req->work);
     378                 :          0 :         __pm_qos_update_request(req, new_value);
     379                 :            : }
     380                 :            : EXPORT_SYMBOL_GPL(pm_qos_update_request);
     381                 :            : 
     382                 :            : /**
     383                 :            :  * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
     384                 :            :  * @req : handle to list element holding a pm_qos request to use
     385                 :            :  * @new_value: defines the temporal qos request
     386                 :            :  * @timeout_us: the effective duration of this qos request in usecs.
     387                 :            :  *
     388                 :            :  * After timeout_us, this qos request is cancelled automatically.
     389                 :            :  */
     390                 :          0 : void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
     391                 :            :                                    unsigned long timeout_us)
     392                 :            : {
     393         [ #  # ]:          0 :         if (!req)
     394                 :            :                 return;
     395 [ #  # ][ #  # ]:          0 :         if (WARN(!pm_qos_request_active(req),
     396                 :            :                  "%s called for unknown object.", __func__))
     397                 :            :                 return;
     398                 :            : 
     399                 :          0 :         cancel_delayed_work_sync(&req->work);
     400                 :            : 
     401                 :          0 :         trace_pm_qos_update_request_timeout(req->pm_qos_class,
     402                 :            :                                             new_value, timeout_us);
     403         [ #  # ]:          0 :         if (new_value != req->node.prio)
     404                 :          0 :                 pm_qos_update_target(
     405                 :          0 :                         pm_qos_array[req->pm_qos_class]->constraints,
     406                 :            :                         &req->node, PM_QOS_UPDATE_REQ, new_value);
     407                 :            : 
     408                 :          0 :         schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
     409                 :            : }
     410                 :            : 
     411                 :            : /**
     412                 :            :  * pm_qos_remove_request - modifies an existing qos request
     413                 :            :  * @req: handle to request list element
     414                 :            :  *
     415                 :            :  * Will remove pm qos request from the list of constraints and
     416                 :            :  * recompute the current target value for the pm_qos_class.  Call this
     417                 :            :  * on slow code paths.
     418                 :            :  */
     419                 :          0 : void pm_qos_remove_request(struct pm_qos_request *req)
     420                 :            : {
     421         [ #  # ]:          0 :         if (!req) /*guard against callers passing in null */
     422                 :            :                 return;
     423                 :            :                 /* silent return to keep pcm code cleaner */
     424                 :            : 
     425         [ #  # ]:          0 :         if (!pm_qos_request_active(req)) {
     426                 :          0 :                 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
     427                 :          0 :                 return;
     428                 :            :         }
     429                 :            : 
     430                 :          0 :         cancel_delayed_work_sync(&req->work);
     431                 :            : 
     432                 :          0 :         trace_pm_qos_remove_request(req->pm_qos_class, PM_QOS_DEFAULT_VALUE);
     433                 :          0 :         pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
     434                 :            :                              &req->node, PM_QOS_REMOVE_REQ,
     435                 :            :                              PM_QOS_DEFAULT_VALUE);
     436                 :          0 :         memset(req, 0, sizeof(*req));
     437                 :            : }
     438                 :            : EXPORT_SYMBOL_GPL(pm_qos_remove_request);
     439                 :            : 
     440                 :            : /**
     441                 :            :  * pm_qos_add_notifier - sets notification entry for changes to target value
     442                 :            :  * @pm_qos_class: identifies which qos target changes should be notified.
     443                 :            :  * @notifier: notifier block managed by caller.
     444                 :            :  *
     445                 :            :  * will register the notifier into a notification chain that gets called
     446                 :            :  * upon changes to the pm_qos_class target value.
     447                 :            :  */
     448                 :          0 : int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
     449                 :            : {
     450                 :            :         int retval;
     451                 :            : 
     452                 :          0 :         retval = blocking_notifier_chain_register(
     453                 :          0 :                         pm_qos_array[pm_qos_class]->constraints->notifiers,
     454                 :            :                         notifier);
     455                 :            : 
     456                 :          0 :         return retval;
     457                 :            : }
     458                 :            : EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
     459                 :            : 
     460                 :            : /**
     461                 :            :  * pm_qos_remove_notifier - deletes notification entry from chain.
     462                 :            :  * @pm_qos_class: identifies which qos target changes are notified.
     463                 :            :  * @notifier: notifier block to be removed.
     464                 :            :  *
     465                 :            :  * will remove the notifier from the notification chain that gets called
     466                 :            :  * upon changes to the pm_qos_class target value.
     467                 :            :  */
     468                 :          0 : int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
     469                 :            : {
     470                 :            :         int retval;
     471                 :            : 
     472                 :          0 :         retval = blocking_notifier_chain_unregister(
     473                 :          0 :                         pm_qos_array[pm_qos_class]->constraints->notifiers,
     474                 :            :                         notifier);
     475                 :            : 
     476                 :          0 :         return retval;
     477                 :            : }
     478                 :            : EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
     479                 :            : 
     480                 :            : /* User space interface to PM QoS classes via misc devices */
     481                 :            : static int register_pm_qos_misc(struct pm_qos_object *qos)
     482                 :            : {
     483                 :          0 :         qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
     484                 :          0 :         qos->pm_qos_power_miscdev.name = qos->name;
     485                 :          0 :         qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
     486                 :            : 
     487                 :          0 :         return misc_register(&qos->pm_qos_power_miscdev);
     488                 :            : }
     489                 :            : 
     490                 :            : static int find_pm_qos_object_by_minor(int minor)
     491                 :            : {
     492                 :            :         int pm_qos_class;
     493                 :            : 
     494         [ #  # ]:          0 :         for (pm_qos_class = PM_QOS_CPU_DMA_LATENCY;
     495                 :          0 :                 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
     496         [ #  # ]:          0 :                 if (minor ==
     497                 :          0 :                         pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
     498                 :            :                         return pm_qos_class;
     499                 :            :         }
     500                 :            :         return -1;
     501                 :            : }
     502                 :            : 
     503                 :          0 : static int pm_qos_power_open(struct inode *inode, struct file *filp)
     504                 :            : {
     505                 :            :         long pm_qos_class;
     506                 :            : 
     507                 :          0 :         pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
     508         [ #  # ]:          0 :         if (pm_qos_class >= PM_QOS_CPU_DMA_LATENCY) {
     509                 :            :                 struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
     510         [ #  # ]:          0 :                 if (!req)
     511                 :            :                         return -ENOMEM;
     512                 :            : 
     513                 :          0 :                 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
     514                 :          0 :                 filp->private_data = req;
     515                 :            : 
     516                 :          0 :                 return 0;
     517                 :            :         }
     518                 :            :         return -EPERM;
     519                 :            : }
     520                 :            : 
     521                 :          0 : static int pm_qos_power_release(struct inode *inode, struct file *filp)
     522                 :            : {
     523                 :            :         struct pm_qos_request *req;
     524                 :            : 
     525                 :          0 :         req = filp->private_data;
     526                 :          0 :         pm_qos_remove_request(req);
     527                 :          0 :         kfree(req);
     528                 :            : 
     529                 :          0 :         return 0;
     530                 :            : }
     531                 :            : 
     532                 :            : 
     533                 :          0 : static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
     534                 :            :                 size_t count, loff_t *f_pos)
     535                 :            : {
     536                 :            :         s32 value;
     537                 :            :         unsigned long flags;
     538                 :          0 :         struct pm_qos_request *req = filp->private_data;
     539                 :            : 
     540         [ #  # ]:          0 :         if (!req)
     541                 :            :                 return -EINVAL;
     542         [ #  # ]:          0 :         if (!pm_qos_request_active(req))
     543                 :            :                 return -EINVAL;
     544                 :            : 
     545                 :          0 :         spin_lock_irqsave(&pm_qos_lock, flags);
     546                 :          0 :         value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
     547                 :            :         spin_unlock_irqrestore(&pm_qos_lock, flags);
     548                 :            : 
     549                 :          0 :         return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
     550                 :            : }
     551                 :            : 
     552                 :          0 : static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
     553                 :            :                 size_t count, loff_t *f_pos)
     554                 :            : {
     555                 :            :         s32 value;
     556                 :            :         struct pm_qos_request *req;
     557                 :            : 
     558         [ #  # ]:          0 :         if (count == sizeof(s32)) {
     559         [ #  # ]:          0 :                 if (copy_from_user(&value, buf, sizeof(s32)))
     560                 :            :                         return -EFAULT;
     561                 :            :         } else {
     562                 :            :                 int ret;
     563                 :            : 
     564                 :            :                 ret = kstrtos32_from_user(buf, count, 16, &value);
     565         [ #  # ]:          0 :                 if (ret)
     566                 :            :                         return ret;
     567                 :            :         }
     568                 :            : 
     569                 :          0 :         req = filp->private_data;
     570                 :          0 :         pm_qos_update_request(req, value);
     571                 :            : 
     572                 :          0 :         return count;
     573                 :            : }
     574                 :            : 
     575                 :            : 
     576                 :          0 : static int __init pm_qos_power_init(void)
     577                 :            : {
     578                 :            :         int ret = 0;
     579                 :            :         int i;
     580                 :            : 
     581                 :            :         BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
     582                 :            : 
     583         [ #  # ]:          0 :         for (i = PM_QOS_CPU_DMA_LATENCY; i < PM_QOS_NUM_CLASSES; i++) {
     584                 :          0 :                 ret = register_pm_qos_misc(pm_qos_array[i]);
     585         [ #  # ]:          0 :                 if (ret < 0) {
     586                 :          0 :                         printk(KERN_ERR "pm_qos_param: %s setup failed\n",
     587                 :          0 :                                pm_qos_array[i]->name);
     588                 :          0 :                         return ret;
     589                 :            :                 }
     590                 :            :         }
     591                 :            : 
     592                 :            :         return ret;
     593                 :            : }
     594                 :            : 
     595                 :            : late_initcall(pm_qos_power_init);

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