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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);