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Diffstat (limited to 'drivers/base/transport_class.c')
| -rw-r--r-- | drivers/base/transport_class.c | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/drivers/base/transport_class.c b/drivers/base/transport_class.c new file mode 100644 index 000000000..5ed86ded6 --- /dev/null +++ b/drivers/base/transport_class.c @@ -0,0 +1,279 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * transport_class.c - implementation of generic transport classes + * using attribute_containers + * + * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com> + * + * The basic idea here is to allow any "device controller" (which + * would most often be a Host Bus Adapter to use the services of one + * or more tranport classes for performing transport specific + * services. Transport specific services are things that the generic + * command layer doesn't want to know about (speed settings, line + * condidtioning, etc), but which the user might be interested in. + * Thus, the HBA's use the routines exported by the transport classes + * to perform these functions. The transport classes export certain + * values to the user via sysfs using attribute containers. + * + * Note: because not every HBA will care about every transport + * attribute, there's a many to one relationship that goes like this: + * + * transport class<-----attribute container<----class device + * + * Usually the attribute container is per-HBA, but the design doesn't + * mandate that. Although most of the services will be specific to + * the actual external storage connection used by the HBA, the generic + * transport class is framed entirely in terms of generic devices to + * allow it to be used by any physical HBA in the system. + */ +#include <linux/export.h> +#include <linux/attribute_container.h> +#include <linux/transport_class.h> + +/** + * transport_class_register - register an initial transport class + * + * @tclass: a pointer to the transport class structure to be initialised + * + * The transport class contains an embedded class which is used to + * identify it. The caller should initialise this structure with + * zeros and then generic class must have been initialised with the + * actual transport class unique name. There's a macro + * DECLARE_TRANSPORT_CLASS() to do this (declared classes still must + * be registered). + * + * Returns 0 on success or error on failure. + */ +int transport_class_register(struct transport_class *tclass) +{ + return class_register(&tclass->class); +} +EXPORT_SYMBOL_GPL(transport_class_register); + +/** + * transport_class_unregister - unregister a previously registered class + * + * @tclass: The transport class to unregister + * + * Must be called prior to deallocating the memory for the transport + * class. + */ +void transport_class_unregister(struct transport_class *tclass) +{ + class_unregister(&tclass->class); +} +EXPORT_SYMBOL_GPL(transport_class_unregister); + +static int anon_transport_dummy_function(struct transport_container *tc, + struct device *dev, + struct device *cdev) +{ + /* do nothing */ + return 0; +} + +/** + * anon_transport_class_register - register an anonymous class + * + * @atc: The anon transport class to register + * + * The anonymous transport class contains both a transport class and a + * container. The idea of an anonymous class is that it never + * actually has any device attributes associated with it (and thus + * saves on container storage). So it can only be used for triggering + * events. Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to + * initialise the anon transport class storage. + */ +int anon_transport_class_register(struct anon_transport_class *atc) +{ + int error; + atc->container.class = &atc->tclass.class; + attribute_container_set_no_classdevs(&atc->container); + error = attribute_container_register(&atc->container); + if (error) + return error; + atc->tclass.setup = anon_transport_dummy_function; + atc->tclass.remove = anon_transport_dummy_function; + return 0; +} +EXPORT_SYMBOL_GPL(anon_transport_class_register); + +/** + * anon_transport_class_unregister - unregister an anon class + * + * @atc: Pointer to the anon transport class to unregister + * + * Must be called prior to deallocating the memory for the anon + * transport class. + */ +void anon_transport_class_unregister(struct anon_transport_class *atc) +{ + if (unlikely(attribute_container_unregister(&atc->container))) + BUG(); +} +EXPORT_SYMBOL_GPL(anon_transport_class_unregister); + +static int transport_setup_classdev(struct attribute_container *cont, + struct device *dev, + struct device *classdev) +{ + struct transport_class *tclass = class_to_transport_class(cont->class); + struct transport_container *tcont = attribute_container_to_transport_container(cont); + + if (tclass->setup) + tclass->setup(tcont, dev, classdev); + + return 0; +} + +/** + * transport_setup_device - declare a new dev for transport class association but don't make it visible yet. + * @dev: the generic device representing the entity being added + * + * Usually, dev represents some component in the HBA system (either + * the HBA itself or a device remote across the HBA bus). This + * routine is simply a trigger point to see if any set of transport + * classes wishes to associate with the added device. This allocates + * storage for the class device and initialises it, but does not yet + * add it to the system or add attributes to it (you do this with + * transport_add_device). If you have no need for a separate setup + * and add operations, use transport_register_device (see + * transport_class.h). + */ + +void transport_setup_device(struct device *dev) +{ + attribute_container_add_device(dev, transport_setup_classdev); +} +EXPORT_SYMBOL_GPL(transport_setup_device); + +static int transport_add_class_device(struct attribute_container *cont, + struct device *dev, + struct device *classdev) +{ + int error = attribute_container_add_class_device(classdev); + struct transport_container *tcont = + attribute_container_to_transport_container(cont); + + if (!error && tcont->statistics) + error = sysfs_create_group(&classdev->kobj, tcont->statistics); + + return error; +} + + +/** + * transport_add_device - declare a new dev for transport class association + * + * @dev: the generic device representing the entity being added + * + * Usually, dev represents some component in the HBA system (either + * the HBA itself or a device remote across the HBA bus). This + * routine is simply a trigger point used to add the device to the + * system and register attributes for it. + */ + +void transport_add_device(struct device *dev) +{ + attribute_container_device_trigger(dev, transport_add_class_device); +} +EXPORT_SYMBOL_GPL(transport_add_device); + +static int transport_configure(struct attribute_container *cont, + struct device *dev, + struct device *cdev) +{ + struct transport_class *tclass = class_to_transport_class(cont->class); + struct transport_container *tcont = attribute_container_to_transport_container(cont); + + if (tclass->configure) + tclass->configure(tcont, dev, cdev); + + return 0; +} + +/** + * transport_configure_device - configure an already set up device + * + * @dev: generic device representing device to be configured + * + * The idea of configure is simply to provide a point within the setup + * process to allow the transport class to extract information from a + * device after it has been setup. This is used in SCSI because we + * have to have a setup device to begin using the HBA, but after we + * send the initial inquiry, we use configure to extract the device + * parameters. The device need not have been added to be configured. + */ +void transport_configure_device(struct device *dev) +{ + attribute_container_device_trigger(dev, transport_configure); +} +EXPORT_SYMBOL_GPL(transport_configure_device); + +static int transport_remove_classdev(struct attribute_container *cont, + struct device *dev, + struct device *classdev) +{ + struct transport_container *tcont = + attribute_container_to_transport_container(cont); + struct transport_class *tclass = class_to_transport_class(cont->class); + + if (tclass->remove) + tclass->remove(tcont, dev, classdev); + + if (tclass->remove != anon_transport_dummy_function) { + if (tcont->statistics) + sysfs_remove_group(&classdev->kobj, tcont->statistics); + attribute_container_class_device_del(classdev); + } + + return 0; +} + + +/** + * transport_remove_device - remove the visibility of a device + * + * @dev: generic device to remove + * + * This call removes the visibility of the device (to the user from + * sysfs), but does not destroy it. To eliminate a device entirely + * you must also call transport_destroy_device. If you don't need to + * do remove and destroy as separate operations, use + * transport_unregister_device() (see transport_class.h) which will + * perform both calls for you. + */ +void transport_remove_device(struct device *dev) +{ + attribute_container_device_trigger(dev, transport_remove_classdev); +} +EXPORT_SYMBOL_GPL(transport_remove_device); + +static void transport_destroy_classdev(struct attribute_container *cont, + struct device *dev, + struct device *classdev) +{ + struct transport_class *tclass = class_to_transport_class(cont->class); + + if (tclass->remove != anon_transport_dummy_function) + put_device(classdev); +} + + +/** + * transport_destroy_device - destroy a removed device + * + * @dev: device to eliminate from the transport class. + * + * This call triggers the elimination of storage associated with the + * transport classdev. Note: all it really does is relinquish a + * reference to the classdev. The memory will not be freed until the + * last reference goes to zero. Note also that the classdev retains a + * reference count on dev, so dev too will remain for as long as the + * transport class device remains around. + */ +void transport_destroy_device(struct device *dev) +{ + attribute_container_remove_device(dev, transport_destroy_classdev); +} +EXPORT_SYMBOL_GPL(transport_destroy_device); |