drivers/staging/vc04_services/interface/vchiq_arm/vchiq_connected.c

   1 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
   2 /* Copyright (c) 2010-2012 Broadcom. All rights reserved. */
   3
   4 #include "vchiq_connected.h"
   5 #include "vchiq_core.h"
   6 #include <linux/module.h>
   7 #include <linux/mutex.h>
   8
   9 #define  MAX_CALLBACKS  10
  10
  11 static   int                        g_connected;
  12 static   int                        g_num_deferred_callbacks;
  13 static   VCHIQ_CONNECTED_CALLBACK_T g_deferred_callback[MAX_CALLBACKS];
  14 static   int                        g_once_init;
  15 static   struct mutex               g_connected_mutex;
  16
  17 /****************************************************************************
  18 *
  19 * Function to initialize our lock.
  20 *
  21 ***************************************************************************/
  22
  23 static void connected_init(void)
  24 {
  25         if (!g_once_init) {
  26                 mutex_init(&g_connected_mutex);
  27                 g_once_init = 1;
  28         }
  29 }
  30
  31 /****************************************************************************
  32 *
  33 * This function is used to defer initialization until the vchiq stack is
  34 * initialized. If the stack is already initialized, then the callback will
  35 * be made immediately, otherwise it will be deferred until
  36 * vchiq_call_connected_callbacks is called.
  37 *
  38 ***************************************************************************/
  39
  40 void vchiq_add_connected_callback(VCHIQ_CONNECTED_CALLBACK_T callback)
  41 {
  42         connected_init();
  43
  44         if (mutex_lock_killable(&g_connected_mutex))
  45                 return;
  46
  47         if (g_connected)
  48                 /* We're already connected. Call the callback immediately. */
  49
  50                 callback();
  51         else {
  52                 if (g_num_deferred_callbacks >= MAX_CALLBACKS)
  53                         vchiq_log_error(vchiq_core_log_level,
  54                                 "There already %d callback registered - "
  55                                 "please increase MAX_CALLBACKS",
  56                                 g_num_deferred_callbacks);
  57                 else {
  58                         g_deferred_callback[g_num_deferred_callbacks] =
  59                                 callback;
  60                         g_num_deferred_callbacks++;
  61                 }
  62         }
  63         mutex_unlock(&g_connected_mutex);
  64 }
  65
  66 /****************************************************************************
  67 *
  68 * This function is called by the vchiq stack once it has been connected to
  69 * the videocore and clients can start to use the stack.
  70 *
  71 ***************************************************************************/
  72
  73 void vchiq_call_connected_callbacks(void)
  74 {
  75         int i;
  76
  77         connected_init();
  78
  79         if (mutex_lock_killable(&g_connected_mutex))
  80                 return;
  81
  82         for (i = 0; i <  g_num_deferred_callbacks; i++)
  83                 g_deferred_callback[i]();
  84
  85         g_num_deferred_callbacks = 0;
  86         g_connected = 1;
  87         mutex_unlock(&g_connected_mutex);
  88 }
  89 EXPORT_SYMBOL(vchiq_add_connected_callback);