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 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 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 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 int error = attribute_container_add_class_device(classdev); 155 struct transport_container *tcont = 156 attribute_container_to_transport_container(cont); 157 158 if (!error && tcont->statistics) 159 error = sysfs_create_group(&classdev->kobj, tcont->statistics); 160 161 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 void transport_add_device(struct device *dev) 177 { 178 attribute_container_device_trigger(dev, transport_add_class_device); 179 } 180 EXPORT_SYMBOL_GPL(transport_add_device); 181 182 static int transport_configure(struct attribute_container *cont, 183 struct device *dev, 184 struct device *cdev) 185 { 186 struct transport_class *tclass = class_to_transport_class(cont->class); 187 struct transport_container *tcont = attribute_container_to_transport_container(cont); 188 189 if (tclass->configure) 190 tclass->configure(tcont, dev, cdev); 191 192 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 void transport_configure_device(struct device *dev) 208 { 209 attribute_container_device_trigger(dev, transport_configure); 210 } 211 EXPORT_SYMBOL_GPL(transport_configure_device); 212 213 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 struct transport_class *tclass = class_to_transport_class(cont->class); 220 221 if (tclass->remove) 222 tclass->remove(tcont, dev, classdev); 223 224 if (tclass->remove != anon_transport_dummy_function) { 225 if (tcont->statistics) 226 sysfs_remove_group(&classdev->kobj, tcont->statistics); 227 attribute_container_class_device_del(classdev); 228 } 229 230 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 void transport_remove_device(struct device *dev) 247 { 248 attribute_container_device_trigger(dev, transport_remove_classdev); 249 } 250 EXPORT_SYMBOL_GPL(transport_remove_device); 251 252 static void transport_destroy_classdev(struct attribute_container *cont, 253 struct device *dev, 254 struct device *classdev) 255 { 256 struct transport_class *tclass = class_to_transport_class(cont->class); 257 258 if (tclass->remove != anon_transport_dummy_function) 259 put_device(classdev); 260 } 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 void transport_destroy_device(struct device *dev) 276 { 277 attribute_container_remove_device(dev, transport_destroy_classdev); 278 } 279 EXPORT_SYMBOL_GPL(transport_destroy_device); 280