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