1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * transport_class.c - implementation of generic transport classes 4 * using attribute_containers 5 * 6 * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com> 7 * 8 * The basic idea here is to allow any "device controller" (which 9 * would most often be a Host Bus Adapter to use the services of one 10 * or more tranport classes for performing transport specific 11 * services. Transport specific services are things that the generic 12 * command layer doesn't want to know about (speed settings, line 13 * condidtioning, etc), but which the user might be interested in. 14 * Thus, the HBA's use the routines exported by the transport classes 15 * to perform these functions. The transport classes export certain 16 * values to the user via sysfs using attribute containers. 17 * 18 * Note: because not every HBA will care about every transport 19 * attribute, there's a many to one relationship that goes like this: 20 * 21 * transport class<-----attribute container<----class device 22 * 23 * Usually the attribute container is per-HBA, but the design doesn't 24 * mandate that. Although most of the services will be specific to 25 * the actual external storage connection used by the HBA, the generic 26 * transport class is framed entirely in terms of generic devices to 27 * allow it to be used by any physical HBA in the system. 28 */ 29 #include <linux/export.h> 30 #include <linux/attribute_container.h> 31 #include <linux/transport_class.h> 32 33 static int transport_remove_classdev(struct attribute_container *cont, 34 struct device *dev, 35 struct device *classdev); 36 37 /** 38 * transport_class_register - register an initial transport class 39 * 40 * @tclass: a pointer to the transport class structure to be initialised 41 * 42 * The transport class contains an embedded class which is used to 43 * identify it. The caller should initialise this structure with 44 * zeros and then generic class must have been initialised with the 45 * actual transport class unique name. There's a macro 46 * DECLARE_TRANSPORT_CLASS() to do this (declared classes still must 47 * be registered). 48 * 49 * Returns 0 on success or error on failure. 50 */ 51 int transport_class_register(struct transport_class *tclass) 52 { 53 return class_register(&tclass->class); 54 } 55 EXPORT_SYMBOL_GPL(transport_class_register); 56 57 /** 58 * transport_class_unregister - unregister a previously registered class 59 * 60 * @tclass: The transport class to unregister 61 * 62 * Must be called prior to deallocating the memory for the transport 63 * class. 64 */ 65 void transport_class_unregister(struct transport_class *tclass) 66 { 67 class_unregister(&tclass->class); 68 } 69 EXPORT_SYMBOL_GPL(transport_class_unregister); 70 71 static int anon_transport_dummy_function(struct transport_container *tc, 72 struct device *dev, 73 struct device *cdev) 74 { 75 /* do nothing */ 76 return 0; 77 } 78 79 /** 80 * anon_transport_class_register - register an anonymous class 81 * 82 * @atc: The anon transport class to register 83 * 84 * The anonymous transport class contains both a transport class and a 85 * container. The idea of an anonymous class is that it never 86 * actually has any device attributes associated with it (and thus 87 * saves on container storage). So it can only be used for triggering 88 * events. Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to 89 * initialise the anon transport class storage. 90 */ 91 int anon_transport_class_register(struct anon_transport_class *atc) 92 { 93 int error; 94 atc->container.class = &atc->tclass.class; 95 attribute_container_set_no_classdevs(&atc->container); 96 error = attribute_container_register(&atc->container); 97 if (error) 98 return error; 99 atc->tclass.setup = anon_transport_dummy_function; 100 atc->tclass.remove = anon_transport_dummy_function; 101 return 0; 102 } 103 EXPORT_SYMBOL_GPL(anon_transport_class_register); 104 105 /** 106 * anon_transport_class_unregister - unregister an anon class 107 * 108 * @atc: Pointer to the anon transport class to unregister 109 * 110 * Must be called prior to deallocating the memory for the anon 111 * transport class. 112 */ 113 void anon_transport_class_unregister(struct anon_transport_class *atc) 114 { 115 if (unlikely(attribute_container_unregister(&atc->container))) 116 BUG(); 117 } 118 EXPORT_SYMBOL_GPL(anon_transport_class_unregister); 119 120 static int transport_setup_classdev(struct attribute_container *cont, 121 struct device *dev, 122 struct device *classdev) 123 { 124 struct transport_class *tclass = class_to_transport_class(cont->class); 125 struct transport_container *tcont = attribute_container_to_transport_container(cont); 126 127 if (tclass->setup) 128 tclass->setup(tcont, dev, classdev); 129 130 return 0; 131 } 132 133 /** 134 * transport_setup_device - declare a new dev for transport class association but don't make it visible yet. 135 * @dev: the generic device representing the entity being added 136 * 137 * Usually, dev represents some component in the HBA system (either 138 * the HBA itself or a device remote across the HBA bus). This 139 * routine is simply a trigger point to see if any set of transport 140 * classes wishes to associate with the added device. This allocates 141 * storage for the class device and initialises it, but does not yet 142 * add it to the system or add attributes to it (you do this with 143 * transport_add_device). If you have no need for a separate setup 144 * and add operations, use transport_register_device (see 145 * transport_class.h). 146 */ 147 148 void transport_setup_device(struct device *dev) 149 { 150 attribute_container_add_device(dev, transport_setup_classdev); 151 } 152 EXPORT_SYMBOL_GPL(transport_setup_device); 153 154 static int transport_add_class_device(struct attribute_container *cont, 155 struct device *dev, 156 struct device *classdev) 157 { 158 struct transport_class *tclass = class_to_transport_class(cont->class); 159 int error = attribute_container_add_class_device(classdev); 160 struct transport_container *tcont = 161 attribute_container_to_transport_container(cont); 162 163 if (error) 164 goto err_remove; 165 166 if (tcont->statistics) { 167 error = sysfs_create_group(&classdev->kobj, tcont->statistics); 168 if (error) 169 goto err_del; 170 } 171 172 return 0; 173 174 err_del: 175 attribute_container_class_device_del(classdev); 176 err_remove: 177 if (tclass->remove) 178 tclass->remove(tcont, dev, classdev); 179 180 return error; 181 } 182 183 184 /** 185 * transport_add_device - declare a new dev for transport class association 186 * 187 * @dev: the generic device representing the entity being added 188 * 189 * Usually, dev represents some component in the HBA system (either 190 * the HBA itself or a device remote across the HBA bus). This 191 * routine is simply a trigger point used to add the device to the 192 * system and register attributes for it. 193 */ 194 int transport_add_device(struct device *dev) 195 { 196 return attribute_container_device_trigger_safe(dev, 197 transport_add_class_device, 198 transport_remove_classdev); 199 } 200 EXPORT_SYMBOL_GPL(transport_add_device); 201 202 static int transport_configure(struct attribute_container *cont, 203 struct device *dev, 204 struct device *cdev) 205 { 206 struct transport_class *tclass = class_to_transport_class(cont->class); 207 struct transport_container *tcont = attribute_container_to_transport_container(cont); 208 209 if (tclass->configure) 210 tclass->configure(tcont, dev, cdev); 211 212 return 0; 213 } 214 215 /** 216 * transport_configure_device - configure an already set up device 217 * 218 * @dev: generic device representing device to be configured 219 * 220 * The idea of configure is simply to provide a point within the setup 221 * process to allow the transport class to extract information from a 222 * device after it has been setup. This is used in SCSI because we 223 * have to have a setup device to begin using the HBA, but after we 224 * send the initial inquiry, we use configure to extract the device 225 * parameters. The device need not have been added to be configured. 226 */ 227 void transport_configure_device(struct device *dev) 228 { 229 attribute_container_device_trigger(dev, transport_configure); 230 } 231 EXPORT_SYMBOL_GPL(transport_configure_device); 232 233 static int transport_remove_classdev(struct attribute_container *cont, 234 struct device *dev, 235 struct device *classdev) 236 { 237 struct transport_container *tcont = 238 attribute_container_to_transport_container(cont); 239 struct transport_class *tclass = class_to_transport_class(cont->class); 240 241 if (tclass->remove) 242 tclass->remove(tcont, dev, classdev); 243 244 if (tclass->remove != anon_transport_dummy_function) { 245 if (tcont->statistics) 246 sysfs_remove_group(&classdev->kobj, tcont->statistics); 247 attribute_container_class_device_del(classdev); 248 } 249 250 return 0; 251 } 252 253 254 /** 255 * transport_remove_device - remove the visibility of a device 256 * 257 * @dev: generic device to remove 258 * 259 * This call removes the visibility of the device (to the user from 260 * sysfs), but does not destroy it. To eliminate a device entirely 261 * you must also call transport_destroy_device. If you don't need to 262 * do remove and destroy as separate operations, use 263 * transport_unregister_device() (see transport_class.h) which will 264 * perform both calls for you. 265 */ 266 void transport_remove_device(struct device *dev) 267 { 268 attribute_container_device_trigger(dev, transport_remove_classdev); 269 } 270 EXPORT_SYMBOL_GPL(transport_remove_device); 271 272 static void transport_destroy_classdev(struct attribute_container *cont, 273 struct device *dev, 274 struct device *classdev) 275 { 276 struct transport_class *tclass = class_to_transport_class(cont->class); 277 278 if (tclass->remove != anon_transport_dummy_function) 279 put_device(classdev); 280 } 281 282 283 /** 284 * transport_destroy_device - destroy a removed device 285 * 286 * @dev: device to eliminate from the transport class. 287 * 288 * This call triggers the elimination of storage associated with the 289 * transport classdev. Note: all it really does is relinquish a 290 * reference to the classdev. The memory will not be freed until the 291 * last reference goes to zero. Note also that the classdev retains a 292 * reference count on dev, so dev too will remain for as long as the 293 * transport class device remains around. 294 */ 295 void transport_destroy_device(struct device *dev) 296 { 297 attribute_container_remove_device(dev, transport_destroy_classdev); 298 } 299 EXPORT_SYMBOL_GPL(transport_destroy_device); 300