drivers/dca/dca-core.c

   1 /*
   2  * Copyright(c) 2007 Intel Corporation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the Free
   6  * Software Foundation; either version 2 of the License, or (at your option)
   7  * any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc., 59
  16  * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17  *
  18  * The full GNU General Public License is included in this distribution in the
  19  * file called COPYING.
  20  */
  21
  22 /*
  23  * This driver supports an interface for DCA clients and providers to meet.
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/notifier.h>
  28 #include <linux/device.h>
  29 #include <linux/dca.h>
  30
  31 MODULE_LICENSE("GPL");
  32
  33 /* For now we're assuming a single, global, DCA provider for the system. */
  34
  35 static DEFINE_SPINLOCK(dca_lock);
  36
  37 static struct dca_provider *global_dca = NULL;
  38
  39 /**
  40  * dca_add_requester - add a dca client to the list
  41  * @dev - the device that wants dca service
  42  */
  43 int dca_add_requester(struct device *dev)
  44 {
  45         int err, slot;
  46
  47         if (!global_dca)
  48                 return -ENODEV;
  49
  50         spin_lock(&dca_lock);
  51         slot = global_dca->ops->add_requester(global_dca, dev);
  52         spin_unlock(&dca_lock);
  53         if (slot < 0)
  54                 return slot;
  55
  56         err = dca_sysfs_add_req(global_dca, dev, slot);
  57         if (err) {
  58                 spin_lock(&dca_lock);
  59                 global_dca->ops->remove_requester(global_dca, dev);
  60                 spin_unlock(&dca_lock);
  61                 return err;
  62         }
  63
  64         return 0;
  65 }
  66 EXPORT_SYMBOL_GPL(dca_add_requester);
  67
  68 /**
  69  * dca_remove_requester - remove a dca client from the list
  70  * @dev - the device that wants dca service
  71  */
  72 int dca_remove_requester(struct device *dev)
  73 {
  74         int slot;
  75         if (!global_dca)
  76                 return -ENODEV;
  77
  78         spin_lock(&dca_lock);
  79         slot = global_dca->ops->remove_requester(global_dca, dev);
  80         spin_unlock(&dca_lock);
  81         if (slot < 0)
  82                 return slot;
  83
  84         dca_sysfs_remove_req(global_dca, slot);
  85         return 0;
  86 }
  87 EXPORT_SYMBOL_GPL(dca_remove_requester);
  88
  89 /**
  90  * dca_get_tag - return the dca tag for the given cpu
  91  * @cpu - the cpuid as returned by get_cpu()
  92  */
  93 u8 dca_get_tag(int cpu)
  94 {
  95         if (!global_dca)
  96                 return -ENODEV;
  97         return global_dca->ops->get_tag(global_dca, cpu);
  98 }
  99 EXPORT_SYMBOL_GPL(dca_get_tag);
 100
 101 /**
 102  * alloc_dca_provider - get data struct for describing a dca provider
 103  * @ops - pointer to struct of dca operation function pointers
 104  * @priv_size - size of extra mem to be added for provider's needs
 105  */
 106 struct dca_provider *alloc_dca_provider(struct dca_ops *ops, int priv_size)
 107 {
 108         struct dca_provider *dca;
 109         int alloc_size;
 110
 111         alloc_size = (sizeof(*dca) + priv_size);
 112         dca = kzalloc(alloc_size, GFP_KERNEL);
 113         if (!dca)
 114                 return NULL;
 115         dca->ops = ops;
 116
 117         return dca;
 118 }
 119 EXPORT_SYMBOL_GPL(alloc_dca_provider);
 120
 121 /**
 122  * free_dca_provider - release the dca provider data struct
 123  * @ops - pointer to struct of dca operation function pointers
 124  * @priv_size - size of extra mem to be added for provider's needs
 125  */
 126 void free_dca_provider(struct dca_provider *dca)
 127 {
 128         kfree(dca);
 129 }
 130 EXPORT_SYMBOL_GPL(free_dca_provider);
 131
 132 static BLOCKING_NOTIFIER_HEAD(dca_provider_chain);
 133
 134 /**
 135  * register_dca_provider - register a dca provider
 136  * @dca - struct created by alloc_dca_provider()
 137  * @dev - device providing dca services
 138  */
 139 int register_dca_provider(struct dca_provider *dca, struct device *dev)
 140 {
 141         int err;
 142
 143         if (global_dca)
 144                 return -EEXIST;
 145         err = dca_sysfs_add_provider(dca, dev);
 146         if (err)
 147                 return err;
 148         global_dca = dca;
 149         blocking_notifier_call_chain(&dca_provider_chain,
 150                                      DCA_PROVIDER_ADD, NULL);
 151         return 0;
 152 }
 153 EXPORT_SYMBOL_GPL(register_dca_provider);
 154
 155 /**
 156  * unregister_dca_provider - remove a dca provider
 157  * @dca - struct created by alloc_dca_provider()
 158  */
 159 void unregister_dca_provider(struct dca_provider *dca)
 160 {
 161         if (!global_dca)
 162                 return;
 163         blocking_notifier_call_chain(&dca_provider_chain,
 164                                      DCA_PROVIDER_REMOVE, NULL);
 165         global_dca = NULL;
 166         dca_sysfs_remove_provider(dca);
 167 }
 168 EXPORT_SYMBOL_GPL(unregister_dca_provider);
 169
 170 /**
 171  * dca_register_notify - register a client's notifier callback
 172  */
 173 void dca_register_notify(struct notifier_block *nb)
 174 {
 175         blocking_notifier_chain_register(&dca_provider_chain, nb);
 176 }
 177 EXPORT_SYMBOL_GPL(dca_register_notify);
 178
 179 /**
 180  * dca_unregister_notify - remove a client's notifier callback
 181  */
 182 void dca_unregister_notify(struct notifier_block *nb)
 183 {
 184         blocking_notifier_chain_unregister(&dca_provider_chain, nb);
 185 }
 186 EXPORT_SYMBOL_GPL(dca_unregister_notify);
 187
 188 static int __init dca_init(void)
 189 {
 190         return dca_sysfs_init();
 191 }
 192
 193 static void __exit dca_exit(void)
 194 {
 195         dca_sysfs_exit();
 196 }
 197
 198 module_init(dca_init);
 199 module_exit(dca_exit);
 200