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 void anon_transport_class_register(struct anon_transport_class *atc) 92 { 93 atc->container.class = &atc->tclass.class; 94 attribute_container_set_no_classdevs(&atc->container); 95 attribute_container_register(&atc->container); 96 atc->tclass.setup = anon_transport_dummy_function; 97 atc->tclass.remove = anon_transport_dummy_function; 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 if (unlikely(attribute_container_unregister(&atc->container))) 112 BUG(); 113 } 114 EXPORT_SYMBOL_GPL(anon_transport_class_unregister); 115 116 static int transport_setup_classdev(struct attribute_container *cont, 117 struct device *dev, 118 struct device *classdev) 119 { 120 struct transport_class *tclass = class_to_transport_class(cont->class); 121 struct transport_container *tcont = attribute_container_to_transport_container(cont); 122 123 if (tclass->setup) 124 tclass->setup(tcont, dev, classdev); 125 126 return 0; 127 } 128 129 /** 130 * transport_setup_device - declare a new dev for transport class association but don't make it visible yet. 131 * @dev: the generic device representing the entity being added 132 * 133 * Usually, dev represents some component in the HBA system (either 134 * the HBA itself or a device remote across the HBA bus). This 135 * routine is simply a trigger point to see if any set of transport 136 * classes wishes to associate with the added device. This allocates 137 * storage for the class device and initialises it, but does not yet 138 * add it to the system or add attributes to it (you do this with 139 * transport_add_device). If you have no need for a separate setup 140 * and add operations, use transport_register_device (see 141 * transport_class.h). 142 */ 143 144 void transport_setup_device(struct device *dev) 145 { 146 attribute_container_add_device(dev, transport_setup_classdev); 147 } 148 EXPORT_SYMBOL_GPL(transport_setup_device); 149 150 static int transport_add_class_device(struct attribute_container *cont, 151 struct device *dev, 152 struct device *classdev) 153 { 154 struct transport_class *tclass = class_to_transport_class(cont->class); 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) 160 goto err_remove; 161 162 if (tcont->statistics) { 163 error = sysfs_create_group(&classdev->kobj, tcont->statistics); 164 if (error) 165 goto err_del; 166 } 167 168 if (tcont->encryption) { 169 error = sysfs_create_group(&classdev->kobj, tcont->encryption); 170 if (error) 171 goto err_del; 172 } 173 174 return 0; 175 176 err_del: 177 attribute_container_class_device_del(classdev); 178 err_remove: 179 if (tclass->remove) 180 tclass->remove(tcont, dev, classdev); 181 182 return error; 183 } 184 185 186 /** 187 * transport_add_device - declare a new dev for transport class association 188 * 189 * @dev: the generic device representing the entity being added 190 * 191 * Usually, dev represents some component in the HBA system (either 192 * the HBA itself or a device remote across the HBA bus). This 193 * routine is simply a trigger point used to add the device to the 194 * system and register attributes for it. 195 */ 196 int transport_add_device(struct device *dev) 197 { 198 return attribute_container_device_trigger_safe(dev, 199 transport_add_class_device, 200 transport_remove_classdev); 201 } 202 EXPORT_SYMBOL_GPL(transport_add_device); 203 204 static int transport_configure(struct attribute_container *cont, 205 struct device *dev, 206 struct device *cdev) 207 { 208 struct transport_class *tclass = class_to_transport_class(cont->class); 209 struct transport_container *tcont = attribute_container_to_transport_container(cont); 210 211 if (tclass->configure) 212 tclass->configure(tcont, dev, cdev); 213 214 return 0; 215 } 216 217 /** 218 * transport_configure_device - configure an already set up device 219 * 220 * @dev: generic device representing device to be configured 221 * 222 * The idea of configure is simply to provide a point within the setup 223 * process to allow the transport class to extract information from a 224 * device after it has been setup. This is used in SCSI because we 225 * have to have a setup device to begin using the HBA, but after we 226 * send the initial inquiry, we use configure to extract the device 227 * parameters. The device need not have been added to be configured. 228 */ 229 void transport_configure_device(struct device *dev) 230 { 231 attribute_container_device_trigger(dev, transport_configure); 232 } 233 EXPORT_SYMBOL_GPL(transport_configure_device); 234 235 static int transport_remove_classdev(struct attribute_container *cont, 236 struct device *dev, 237 struct device *classdev) 238 { 239 struct transport_container *tcont = 240 attribute_container_to_transport_container(cont); 241 struct transport_class *tclass = class_to_transport_class(cont->class); 242 243 if (tclass->remove) 244 tclass->remove(tcont, dev, classdev); 245 246 if (tclass->remove != anon_transport_dummy_function) { 247 if (tcont->statistics) 248 sysfs_remove_group(&classdev->kobj, tcont->statistics); 249 if (tcont->encryption) 250 sysfs_remove_group(&classdev->kobj, tcont->encryption); 251 attribute_container_class_device_del(classdev); 252 } 253 254 return 0; 255 } 256 257 258 /** 259 * transport_remove_device - remove the visibility of a device 260 * 261 * @dev: generic device to remove 262 * 263 * This call removes the visibility of the device (to the user from 264 * sysfs), but does not destroy it. To eliminate a device entirely 265 * you must also call transport_destroy_device. If you don't need to 266 * do remove and destroy as separate operations, use 267 * transport_unregister_device() (see transport_class.h) which will 268 * perform both calls for you. 269 */ 270 void transport_remove_device(struct device *dev) 271 { 272 attribute_container_device_trigger(dev, transport_remove_classdev); 273 } 274 EXPORT_SYMBOL_GPL(transport_remove_device); 275 276 static void transport_destroy_classdev(struct attribute_container *cont, 277 struct device *dev, 278 struct device *classdev) 279 { 280 struct transport_class *tclass = class_to_transport_class(cont->class); 281 282 if (tclass->remove != anon_transport_dummy_function) 283 put_device(classdev); 284 } 285 286 287 /** 288 * transport_destroy_device - destroy a removed device 289 * 290 * @dev: device to eliminate from the transport class. 291 * 292 * This call triggers the elimination of storage associated with the 293 * transport classdev. Note: all it really does is relinquish a 294 * reference to the classdev. The memory will not be freed until the 295 * last reference goes to zero. Note also that the classdev retains a 296 * reference count on dev, so dev too will remain for as long as the 297 * transport class device remains around. 298 */ 299 void transport_destroy_device(struct device *dev) 300 { 301 attribute_container_remove_device(dev, transport_destroy_classdev); 302 } 303 EXPORT_SYMBOL_GPL(transport_destroy_device); 304