drivers/base/transport_class.c

   1 /*
   2  * transport_class.c - implementation of generic transport classes
   3  *                     using attribute_containers
   4  *
   5  * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
   6  *
   7  * This file is licensed under GPLv2
   8  *
   9  * The basic idea here is to allow any "device controller" (which
  10  * would most often be a Host Bus Adapter to use the services of one
  11  * or more tranport classes for performing transport specific
  12  * services.  Transport specific services are things that the generic
  13  * command layer doesn't want to know about (speed settings, line
  14  * condidtioning, etc), but which the user might be interested in.
  15  * Thus, the HBA's use the routines exported by the transport classes
  16  * to perform these functions.  The transport classes export certain
  17  * values to the user via sysfs using attribute containers.
  18  *
  19  * Note: because not every HBA will care about every transport
  20  * attribute, there's a many to one relationship that goes like this:
  21  *
  22  * transport class<-----attribute container<----class device
  23  *
  24  * Usually the attribute container is per-HBA, but the design doesn't
  25  * mandate that.  Although most of the services will be specific to
  26  * the actual external storage connection used by the HBA, the generic
  27  * transport class is framed entirely in terms of generic devices to
  28  * allow it to be used by any physical HBA in the system.
  29  */
  30 #include <linux/export.h>
  31 #include <linux/attribute_container.h>
  32 #include <linux/transport_class.h>
  33
  34 /**
  35  * transport_class_register - register an initial transport class
  36  *
  37  * @tclass:     a pointer to the transport class structure to be initialised
  38  *
  39  * The transport class contains an embedded class which is used to
  40  * identify it.  The caller should initialise this structure with
  41  * zeros and then generic class must have been initialised with the
  42  * actual transport class unique name.  There's a macro
  43  * DECLARE_TRANSPORT_CLASS() to do this (declared classes still must
  44  * be registered).
  45  *
  46  * Returns 0 on success or error on failure.
  47  */
  48 int transport_class_register(struct transport_class *tclass)
  49 {
  50         return class_register(&tclass->class);
  51 }
  52 EXPORT_SYMBOL_GPL(transport_class_register);
  53
  54 /**
  55  * transport_class_unregister - unregister a previously registered class
  56  *
  57  * @tclass: The transport class to unregister
  58  *
  59  * Must be called prior to deallocating the memory for the transport
  60  * class.
  61  */
  62 void transport_class_unregister(struct transport_class *tclass)
  63 {
  64         class_unregister(&tclass->class);
  65 }
  66 EXPORT_SYMBOL_GPL(transport_class_unregister);
  67
  68 static int anon_transport_dummy_function(struct transport_container *tc,
  69                                          struct device *dev,
  70                                          struct device *cdev)
  71 {
  72         /* do nothing */
  73         return 0;
  74 }
  75
  76 /**
  77  * anon_transport_class_register - register an anonymous class
  78  *
  79  * @atc: The anon transport class to register
  80  *
  81  * The anonymous transport class contains both a transport class and a
  82  * container.  The idea of an anonymous class is that it never
  83  * actually has any device attributes associated with it (and thus
  84  * saves on container storage).  So it can only be used for triggering
  85  * events.  Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to
  86  * initialise the anon transport class storage.
  87  */
  88 int anon_transport_class_register(struct anon_transport_class *atc)
  89 {
  90         int error;
  91         atc->container.class = &atc->tclass.class;
  92         attribute_container_set_no_classdevs(&atc->container);
  93         error = attribute_container_register(&atc->container);
  94         if (error)
  95                 return error;
  96         atc->tclass.setup = anon_transport_dummy_function;
  97         atc->tclass.remove = anon_transport_dummy_function;
  98         return 0;
  99 }
 100 EXPORT_SYMBOL_GPL(anon_transport_class_register);
 101
 102 /**
 103  * anon_transport_class_unregister - unregister an anon class
 104  *
 105  * @atc: Pointer to the anon transport class to unregister
 106  *
 107  * Must be called prior to deallocating the memory for the anon
 108  * transport class.
 109  */
 110 void anon_transport_class_unregister(struct anon_transport_class *atc)
 111 {
 112         if (unlikely(attribute_container_unregister(&atc->container)))
 113                 BUG();
 114 }
 115 EXPORT_SYMBOL_GPL(anon_transport_class_unregister);
 116
 117 static int transport_setup_classdev(struct attribute_container *cont,
 118                                     struct device *dev,
 119                                     struct device *classdev)
 120 {
 121         struct transport_class *tclass = class_to_transport_class(cont->class);
 122         struct transport_container *tcont = attribute_container_to_transport_container(cont);
 123
 124         if (tclass->setup)
 125                 tclass->setup(tcont, dev, classdev);
 126
 127         return 0;
 128 }
 129
 130 /**
 131  * transport_setup_device - declare a new dev for transport class association but don't make it visible yet.
 132  * @dev: the generic device representing the entity being added
 133  *
 134  * Usually, dev represents some component in the HBA system (either
 135  * the HBA itself or a device remote across the HBA bus).  This
 136  * routine is simply a trigger point to see if any set of transport
 137  * classes wishes to associate with the added device.  This allocates
 138  * storage for the class device and initialises it, but does not yet
 139  * add it to the system or add attributes to it (you do this with
 140  * transport_add_device).  If you have no need for a separate setup
 141  * and add operations, use transport_register_device (see
 142  * transport_class.h).
 143  */
 144
 145 void transport_setup_device(struct device *dev)
 146 {
 147         attribute_container_add_device(dev, transport_setup_classdev);
 148 }
 149 EXPORT_SYMBOL_GPL(transport_setup_device);
 150
 151 static int transport_add_class_device(struct attribute_container *cont,
 152                                       struct device *dev,
 153                                       struct device *classdev)
 154 {
 155         int error = attribute_container_add_class_device(classdev);
 156         struct transport_container *tcont =
 157                 attribute_container_to_transport_container(cont);
 158
 159         if (!error && tcont->statistics)
 160                 error = sysfs_create_group(&classdev->kobj, tcont->statistics);
 161
 162         return error;
 163 }
 164
 165
 166 /**
 167  * transport_add_device - declare a new dev for transport class association
 168  *
 169  * @dev: the generic device representing the entity being added
 170  *
 171  * Usually, dev represents some component in the HBA system (either
 172  * the HBA itself or a device remote across the HBA bus).  This
 173  * routine is simply a trigger point used to add the device to the
 174  * system and register attributes for it.
 175  */
 176
 177 void transport_add_device(struct device *dev)
 178 {
 179         attribute_container_device_trigger(dev, transport_add_class_device);
 180 }
 181 EXPORT_SYMBOL_GPL(transport_add_device);
 182
 183 static int transport_configure(struct attribute_container *cont,
 184                                struct device *dev,
 185                                struct device *cdev)
 186 {
 187         struct transport_class *tclass = class_to_transport_class(cont->class);
 188         struct transport_container *tcont = attribute_container_to_transport_container(cont);
 189
 190         if (tclass->configure)
 191                 tclass->configure(tcont, dev, cdev);
 192
 193         return 0;
 194 }
 195
 196 /**
 197  * transport_configure_device - configure an already set up device
 198  *
 199  * @dev: generic device representing device to be configured
 200  *
 201  * The idea of configure is simply to provide a point within the setup
 202  * process to allow the transport class to extract information from a
 203  * device after it has been setup.  This is used in SCSI because we
 204  * have to have a setup device to begin using the HBA, but after we
 205  * send the initial inquiry, we use configure to extract the device
 206  * parameters.  The device need not have been added to be configured.
 207  */
 208 void transport_configure_device(struct device *dev)
 209 {
 210         attribute_container_device_trigger(dev, transport_configure);
 211 }
 212 EXPORT_SYMBOL_GPL(transport_configure_device);
 213
 214 static int transport_remove_classdev(struct attribute_container *cont,
 215                                      struct device *dev,
 216                                      struct device *classdev)
 217 {
 218         struct transport_container *tcont =
 219                 attribute_container_to_transport_container(cont);
 220         struct transport_class *tclass = class_to_transport_class(cont->class);
 221
 222         if (tclass->remove)
 223                 tclass->remove(tcont, dev, classdev);
 224
 225         if (tclass->remove != anon_transport_dummy_function) {
 226                 if (tcont->statistics)
 227                         sysfs_remove_group(&classdev->kobj, tcont->statistics);
 228                 attribute_container_class_device_del(classdev);
 229         }
 230
 231         return 0;
 232 }
 233
 234
 235 /**
 236  * transport_remove_device - remove the visibility of a device
 237  *
 238  * @dev: generic device to remove
 239  *
 240  * This call removes the visibility of the device (to the user from
 241  * sysfs), but does not destroy it.  To eliminate a device entirely
 242  * you must also call transport_destroy_device.  If you don't need to
 243  * do remove and destroy as separate operations, use
 244  * transport_unregister_device() (see transport_class.h) which will
 245  * perform both calls for you.
 246  */
 247 void transport_remove_device(struct device *dev)
 248 {
 249         attribute_container_device_trigger(dev, transport_remove_classdev);
 250 }
 251 EXPORT_SYMBOL_GPL(transport_remove_device);
 252
 253 static void transport_destroy_classdev(struct attribute_container *cont,
 254                                       struct device *dev,
 255                                       struct device *classdev)
 256 {
 257         struct transport_class *tclass = class_to_transport_class(cont->class);
 258
 259         if (tclass->remove != anon_transport_dummy_function)
 260                 put_device(classdev);
 261 }
 262
 263
 264 /**
 265  * transport_destroy_device - destroy a removed device
 266  *
 267  * @dev: device to eliminate from the transport class.
 268  *
 269  * This call triggers the elimination of storage associated with the
 270  * transport classdev.  Note: all it really does is relinquish a
 271  * reference to the classdev.  The memory will not be freed until the
 272  * last reference goes to zero.  Note also that the classdev retains a
 273  * reference count on dev, so dev too will remain for as long as the
 274  * transport class device remains around.
 275  */
 276 void transport_destroy_device(struct device *dev)
 277 {
 278         attribute_container_remove_device(dev, transport_destroy_classdev);
 279 }
 280 EXPORT_SYMBOL_GPL(transport_destroy_device);