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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 : : /** 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 : 3 : int transport_class_register(struct transport_class *tclass) 48 : : { 49 : 3 : 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 : 0 : void transport_class_unregister(struct transport_class *tclass) 62 : : { 63 : 0 : class_unregister(&tclass->class); 64 : 0 : } 65 : : EXPORT_SYMBOL_GPL(transport_class_unregister); 66 : : 67 : 0 : static int anon_transport_dummy_function(struct transport_container *tc, 68 : : struct device *dev, 69 : : struct device *cdev) 70 : : { 71 : : /* do nothing */ 72 : 0 : 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 : 0 : int anon_transport_class_register(struct anon_transport_class *atc) 88 : : { 89 : : int error; 90 : 0 : atc->container.class = &atc->tclass.class; 91 : : attribute_container_set_no_classdevs(&atc->container); 92 : 0 : error = attribute_container_register(&atc->container); 93 : 0 : if (error) 94 : : return error; 95 : 0 : atc->tclass.setup = anon_transport_dummy_function; 96 : 0 : atc->tclass.remove = anon_transport_dummy_function; 97 : 0 : 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 : 0 : void anon_transport_class_unregister(struct anon_transport_class *atc) 110 : : { 111 : 0 : if (unlikely(attribute_container_unregister(&atc->container))) 112 : 0 : BUG(); 113 : 0 : } 114 : : EXPORT_SYMBOL_GPL(anon_transport_class_unregister); 115 : : 116 : 0 : static int transport_setup_classdev(struct attribute_container *cont, 117 : : struct device *dev, 118 : : struct device *classdev) 119 : : { 120 : 0 : struct transport_class *tclass = class_to_transport_class(cont->class); 121 : : struct transport_container *tcont = attribute_container_to_transport_container(cont); 122 : : 123 : 0 : if (tclass->setup) 124 : 0 : tclass->setup(tcont, dev, classdev); 125 : : 126 : 0 : 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 : 0 : void transport_setup_device(struct device *dev) 145 : : { 146 : 0 : attribute_container_add_device(dev, transport_setup_classdev); 147 : 0 : } 148 : : EXPORT_SYMBOL_GPL(transport_setup_device); 149 : : 150 : 0 : static int transport_add_class_device(struct attribute_container *cont, 151 : : struct device *dev, 152 : : struct device *classdev) 153 : : { 154 : 0 : int error = attribute_container_add_class_device(classdev); 155 : : struct transport_container *tcont = 156 : : attribute_container_to_transport_container(cont); 157 : : 158 : 0 : if (!error && tcont->statistics) 159 : 0 : error = sysfs_create_group(&classdev->kobj, tcont->statistics); 160 : : 161 : 0 : return error; 162 : : } 163 : : 164 : : 165 : : /** 166 : : * transport_add_device - declare a new dev for transport class association 167 : : * 168 : : * @dev: the generic device representing the entity being added 169 : : * 170 : : * Usually, dev represents some component in the HBA system (either 171 : : * the HBA itself or a device remote across the HBA bus). This 172 : : * routine is simply a trigger point used to add the device to the 173 : : * system and register attributes for it. 174 : : */ 175 : : 176 : 0 : void transport_add_device(struct device *dev) 177 : : { 178 : 0 : attribute_container_device_trigger(dev, transport_add_class_device); 179 : 0 : } 180 : : EXPORT_SYMBOL_GPL(transport_add_device); 181 : : 182 : 0 : static int transport_configure(struct attribute_container *cont, 183 : : struct device *dev, 184 : : struct device *cdev) 185 : : { 186 : 0 : struct transport_class *tclass = class_to_transport_class(cont->class); 187 : : struct transport_container *tcont = attribute_container_to_transport_container(cont); 188 : : 189 : 0 : if (tclass->configure) 190 : 0 : tclass->configure(tcont, dev, cdev); 191 : : 192 : 0 : return 0; 193 : : } 194 : : 195 : : /** 196 : : * transport_configure_device - configure an already set up device 197 : : * 198 : : * @dev: generic device representing device to be configured 199 : : * 200 : : * The idea of configure is simply to provide a point within the setup 201 : : * process to allow the transport class to extract information from a 202 : : * device after it has been setup. This is used in SCSI because we 203 : : * have to have a setup device to begin using the HBA, but after we 204 : : * send the initial inquiry, we use configure to extract the device 205 : : * parameters. The device need not have been added to be configured. 206 : : */ 207 : 0 : void transport_configure_device(struct device *dev) 208 : : { 209 : 0 : attribute_container_device_trigger(dev, transport_configure); 210 : 0 : } 211 : : EXPORT_SYMBOL_GPL(transport_configure_device); 212 : : 213 : 0 : static int transport_remove_classdev(struct attribute_container *cont, 214 : : struct device *dev, 215 : : struct device *classdev) 216 : : { 217 : : struct transport_container *tcont = 218 : : attribute_container_to_transport_container(cont); 219 : 0 : struct transport_class *tclass = class_to_transport_class(cont->class); 220 : : 221 : 0 : if (tclass->remove) 222 : 0 : tclass->remove(tcont, dev, classdev); 223 : : 224 : 0 : if (tclass->remove != anon_transport_dummy_function) { 225 : 0 : if (tcont->statistics) 226 : 0 : sysfs_remove_group(&classdev->kobj, tcont->statistics); 227 : 0 : attribute_container_class_device_del(classdev); 228 : : } 229 : : 230 : 0 : return 0; 231 : : } 232 : : 233 : : 234 : : /** 235 : : * transport_remove_device - remove the visibility of a device 236 : : * 237 : : * @dev: generic device to remove 238 : : * 239 : : * This call removes the visibility of the device (to the user from 240 : : * sysfs), but does not destroy it. To eliminate a device entirely 241 : : * you must also call transport_destroy_device. If you don't need to 242 : : * do remove and destroy as separate operations, use 243 : : * transport_unregister_device() (see transport_class.h) which will 244 : : * perform both calls for you. 245 : : */ 246 : 0 : void transport_remove_device(struct device *dev) 247 : : { 248 : 0 : attribute_container_device_trigger(dev, transport_remove_classdev); 249 : 0 : } 250 : : EXPORT_SYMBOL_GPL(transport_remove_device); 251 : : 252 : 0 : static void transport_destroy_classdev(struct attribute_container *cont, 253 : : struct device *dev, 254 : : struct device *classdev) 255 : : { 256 : 0 : struct transport_class *tclass = class_to_transport_class(cont->class); 257 : : 258 : 0 : if (tclass->remove != anon_transport_dummy_function) 259 : 0 : put_device(classdev); 260 : 0 : } 261 : : 262 : : 263 : : /** 264 : : * transport_destroy_device - destroy a removed device 265 : : * 266 : : * @dev: device to eliminate from the transport class. 267 : : * 268 : : * This call triggers the elimination of storage associated with the 269 : : * transport classdev. Note: all it really does is relinquish a 270 : : * reference to the classdev. The memory will not be freed until the 271 : : * last reference goes to zero. Note also that the classdev retains a 272 : : * reference count on dev, so dev too will remain for as long as the 273 : : * transport class device remains around. 274 : : */ 275 : 0 : void transport_destroy_device(struct device *dev) 276 : : { 277 : 0 : attribute_container_remove_device(dev, transport_destroy_classdev); 278 : 0 : } 279 : : EXPORT_SYMBOL_GPL(transport_destroy_device);