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 #define DCA_VERSION "1.4"
  32
  33 MODULE_VERSION(DCA_VERSION);
  34 MODULE_LICENSE("GPL");
  35 MODULE_AUTHOR("Intel Corporation");
  36
  37 static DEFINE_SPINLOCK(dca_lock);
  38
  39 static LIST_HEAD(dca_providers);
  40
  41 static struct dca_provider *dca_find_provider_by_dev(struct device *dev)
  42 {
  43         struct dca_provider *dca, *ret = NULL;
  44
  45         list_for_each_entry(dca, &dca_providers, node) {
  46                 if ((!dev) || (dca->ops->dev_managed(dca, dev))) {
  47                         ret = dca;
  48                         break;
  49                 }
  50         }
  51
  52         return ret;
  53 }
  54
  55 /**
  56  * dca_add_requester - add a dca client to the list
  57  * @dev - the device that wants dca service
  58  */
  59 int dca_add_requester(struct device *dev)
  60 {
  61         struct dca_provider *dca;
  62         int err, slot = -ENODEV;
  63
  64         if (!dev)
  65                 return -EFAULT;
  66
  67         spin_lock(&dca_lock);
  68
  69         /* check if the requester has not been added already */
  70         dca = dca_find_provider_by_dev(dev);
  71         if (dca) {
  72                 spin_unlock(&dca_lock);
  73                 return -EEXIST;
  74         }
  75
  76         list_for_each_entry(dca, &dca_providers, node) {
  77                 slot = dca->ops->add_requester(dca, dev);
  78                 if (slot >= 0)
  79                         break;
  80         }
  81         if (slot < 0) {
  82                 spin_unlock(&dca_lock);
  83                 return slot;
  84         }
  85
  86         err = dca_sysfs_add_req(dca, dev, slot);
  87         if (err) {
  88                 dca->ops->remove_requester(dca, dev);
  89                 spin_unlock(&dca_lock);
  90                 return err;
  91         }
  92
  93         spin_unlock(&dca_lock);
  94         return 0;
  95 }
  96 EXPORT_SYMBOL_GPL(dca_add_requester);
  97
  98 /**
  99  * dca_remove_requester - remove a dca client from the list
 100  * @dev - the device that wants dca service
 101  */
 102 int dca_remove_requester(struct device *dev)
 103 {
 104         struct dca_provider *dca;
 105         int slot;
 106
 107         if (!dev)
 108                 return -EFAULT;
 109
 110         spin_lock(&dca_lock);
 111         dca = dca_find_provider_by_dev(dev);
 112         if (!dca) {
 113                 spin_unlock(&dca_lock);
 114                 return -ENODEV;
 115         }
 116         slot = dca->ops->remove_requester(dca, dev);
 117         if (slot < 0) {
 118                 spin_unlock(&dca_lock);
 119                 return slot;
 120         }
 121
 122         dca_sysfs_remove_req(dca, slot);
 123
 124         spin_unlock(&dca_lock);
 125         return 0;
 126 }
 127 EXPORT_SYMBOL_GPL(dca_remove_requester);
 128
 129 /**
 130  * dca_common_get_tag - return the dca tag (serves both new and old api)
 131  * @dev - the device that wants dca service
 132  * @cpu - the cpuid as returned by get_cpu()
 133  */
 134 u8 dca_common_get_tag(struct device *dev, int cpu)
 135 {
 136         struct dca_provider *dca;
 137         u8 tag;
 138
 139         spin_lock(&dca_lock);
 140
 141         dca = dca_find_provider_by_dev(dev);
 142         if (!dca) {
 143                 spin_unlock(&dca_lock);
 144                 return -ENODEV;
 145         }
 146         tag = dca->ops->get_tag(dca, dev, cpu);
 147
 148         spin_unlock(&dca_lock);
 149         return tag;
 150 }
 151
 152 /**
 153  * dca3_get_tag - return the dca tag to the requester device
 154  *                for the given cpu (new api)
 155  * @dev - the device that wants dca service
 156  * @cpu - the cpuid as returned by get_cpu()
 157  */
 158 u8 dca3_get_tag(struct device *dev, int cpu)
 159 {
 160         if (!dev)
 161                 return -EFAULT;
 162
 163         return dca_common_get_tag(dev, cpu);
 164 }
 165 EXPORT_SYMBOL_GPL(dca3_get_tag);
 166
 167 /**
 168  * dca_get_tag - return the dca tag for the given cpu (old api)
 169  * @cpu - the cpuid as returned by get_cpu()
 170  */
 171 u8 dca_get_tag(int cpu)
 172 {
 173         struct device *dev = NULL;
 174
 175         return dca_common_get_tag(dev, cpu);
 176 }
 177 EXPORT_SYMBOL_GPL(dca_get_tag);
 178
 179 /**
 180  * alloc_dca_provider - get data struct for describing a dca provider
 181  * @ops - pointer to struct of dca operation function pointers
 182  * @priv_size - size of extra mem to be added for provider's needs
 183  */
 184 struct dca_provider *alloc_dca_provider(struct dca_ops *ops, int priv_size)
 185 {
 186         struct dca_provider *dca;
 187         int alloc_size;
 188
 189         alloc_size = (sizeof(*dca) + priv_size);
 190         dca = kzalloc(alloc_size, GFP_KERNEL);
 191         if (!dca)
 192                 return NULL;
 193         dca->ops = ops;
 194
 195         return dca;
 196 }
 197 EXPORT_SYMBOL_GPL(alloc_dca_provider);
 198
 199 /**
 200  * free_dca_provider - release the dca provider data struct
 201  * @ops - pointer to struct of dca operation function pointers
 202  * @priv_size - size of extra mem to be added for provider's needs
 203  */
 204 void free_dca_provider(struct dca_provider *dca)
 205 {
 206         kfree(dca);
 207 }
 208 EXPORT_SYMBOL_GPL(free_dca_provider);
 209
 210 static BLOCKING_NOTIFIER_HEAD(dca_provider_chain);
 211
 212 /**
 213  * register_dca_provider - register a dca provider
 214  * @dca - struct created by alloc_dca_provider()
 215  * @dev - device providing dca services
 216  */
 217 int register_dca_provider(struct dca_provider *dca, struct device *dev)
 218 {
 219         int err;
 220
 221         err = dca_sysfs_add_provider(dca, dev);
 222         if (err)
 223                 return err;
 224         list_add(&dca->node, &dca_providers);
 225         blocking_notifier_call_chain(&dca_provider_chain,
 226                                      DCA_PROVIDER_ADD, NULL);
 227         return 0;
 228 }
 229 EXPORT_SYMBOL_GPL(register_dca_provider);
 230
 231 /**
 232  * unregister_dca_provider - remove a dca provider
 233  * @dca - struct created by alloc_dca_provider()
 234  */
 235 void unregister_dca_provider(struct dca_provider *dca)
 236 {
 237         blocking_notifier_call_chain(&dca_provider_chain,
 238                                      DCA_PROVIDER_REMOVE, NULL);
 239         list_del(&dca->node);
 240         dca_sysfs_remove_provider(dca);
 241 }
 242 EXPORT_SYMBOL_GPL(unregister_dca_provider);
 243
 244 /**
 245  * dca_register_notify - register a client's notifier callback
 246  */
 247 void dca_register_notify(struct notifier_block *nb)
 248 {
 249         blocking_notifier_chain_register(&dca_provider_chain, nb);
 250 }
 251 EXPORT_SYMBOL_GPL(dca_register_notify);
 252
 253 /**
 254  * dca_unregister_notify - remove a client's notifier callback
 255  */
 256 void dca_unregister_notify(struct notifier_block *nb)
 257 {
 258         blocking_notifier_chain_unregister(&dca_provider_chain, nb);
 259 }
 260 EXPORT_SYMBOL_GPL(dca_unregister_notify);
 261
 262 static int __init dca_init(void)
 263 {
 264         printk(KERN_ERR "dca service started, version %s\n", DCA_VERSION);
 265         return dca_sysfs_init();
 266 }
 267
 268 static void __exit dca_exit(void)
 269 {
 270         dca_sysfs_exit();
 271 }
 272
 273 module_init(dca_init);
 274 module_exit(dca_exit);
 275