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 transport_container *tc, 68 struct device *dev, 69 struct class_device *cdev) 70 { 71 /* do nothing */ 72 return 0; 73 } 74 75 /** 76 * anon_transport_class_register - register an anonymous class 77 * 78 * @atc: The anon transport class to register 79 * 80 * The anonymous transport class contains both a transport class and a 81 * container. The idea of an anonymous class is that it never 82 * actually has any device attributes associated with it (and thus 83 * saves on container storage). So it can only be used for triggering 84 * events. Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to 85 * initialise the anon transport class storage. 86 */ 87 int anon_transport_class_register(struct anon_transport_class *atc) 88 { 89 int error; 90 atc->container.class = &atc->tclass.class; 91 attribute_container_set_no_classdevs(&atc->container); 92 error = attribute_container_register(&atc->container); 93 if (error) 94 return error; 95 atc->tclass.setup = anon_transport_dummy_function; 96 atc->tclass.remove = anon_transport_dummy_function; 97 return 0; 98 } 99 EXPORT_SYMBOL_GPL(anon_transport_class_register); 100 101 /** 102 * anon_transport_class_unregister - unregister an anon class 103 * 104 * @atc: Pointer to the anon transport class to unregister 105 * 106 * Must be called prior to deallocating the memory for the anon 107 * transport class. 108 */ 109 void anon_transport_class_unregister(struct anon_transport_class *atc) 110 { 111 attribute_container_unregister(&atc->container); 112 } 113 EXPORT_SYMBOL_GPL(anon_transport_class_unregister); 114 115 static int transport_setup_classdev(struct attribute_container *cont, 116 struct device *dev, 117 struct class_device *classdev) 118 { 119 struct transport_class *tclass = class_to_transport_class(cont->class); 120 struct transport_container *tcont = attribute_container_to_transport_container(cont); 121 122 if (tclass->setup) 123 tclass->setup(tcont, dev, classdev); 124 125 return 0; 126 } 127 128 /** 129 * transport_setup_device - declare a new dev for transport class association 130 * but don't make it visible yet. 131 * 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 class_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 class_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 class_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 class_device *classdev) 256 { 257 struct transport_class *tclass = class_to_transport_class(cont->class); 258 259 if (tclass->remove != anon_transport_dummy_function) 260 class_device_put(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); 281