| 1 |
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| 2 | |
| 3 | * Copyright (c) 2019-2020 Intel Corporation
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| 4 | *
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| 5 | * Please see Documentation/driver-api/auxiliary_bus.rst for more information.
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| 6 |
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| 7 |
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| 8 | #ifndef _AUXILIARY_BUS_H_
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| 9 | #define _AUXILIARY_BUS_H_
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| 10 |
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| 11 | #include <linux/device.h>
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| 12 | #include <linux/device-id/auxiliary.h>
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| 13 |
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| 14 | |
| 15 | * DOC: DEVICE_LIFESPAN
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| 16 | *
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| 17 | * The registering driver is the entity that allocates memory for the
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| 18 | * auxiliary_device and registers it on the auxiliary bus. It is important to
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| 19 | * note that, as opposed to the platform bus, the registering driver is wholly
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| 20 | * responsible for the management of the memory used for the device object.
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| 21 | *
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| 22 | * To be clear the memory for the auxiliary_device is freed in the release()
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| 23 | * callback defined by the registering driver. The registering driver should
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| 24 | * only call auxiliary_device_delete() and then auxiliary_device_uninit() when
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| 25 | * it is done with the device. The release() function is then automatically
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| 26 | * called if and when other code releases their reference to the devices.
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| 27 | *
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| 28 | * A parent object, defined in the shared header file, contains the
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| 29 | * auxiliary_device. It also contains a pointer to the shared object(s), which
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| 30 | * also is defined in the shared header. Both the parent object and the shared
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| 31 | * object(s) are allocated by the registering driver. This layout allows the
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| 32 | * auxiliary_driver's registering module to perform a container_of() call to go
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| 33 | * from the pointer to the auxiliary_device, that is passed during the call to
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| 34 | * the auxiliary_driver's probe function, up to the parent object, and then
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| 35 | * have access to the shared object(s).
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| 36 | *
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| 37 | * The memory for the shared object(s) must have a lifespan equal to, or
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| 38 | * greater than, the lifespan of the memory for the auxiliary_device. The
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| 39 | * auxiliary_driver should only consider that the shared object is valid as
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| 40 | * long as the auxiliary_device is still registered on the auxiliary bus. It
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| 41 | * is up to the registering driver to manage (e.g. free or keep available) the
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| 42 | * memory for the shared object beyond the life of the auxiliary_device.
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| 43 | *
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| 44 | * The registering driver must unregister all auxiliary devices before its own
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| 45 | * driver.remove() is completed. An easy way to ensure this is to use the
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| 46 | * devm_add_action_or_reset() call to register a function against the parent
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| 47 | * device which unregisters the auxiliary device object(s).
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| 48 | *
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| 49 | * Finally, any operations which operate on the auxiliary devices must continue
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| 50 | * to function (if only to return an error) after the registering driver
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| 51 | * unregisters the auxiliary device.
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| 52 |
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| 53 |
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| 54 | |
| 55 | * struct auxiliary_device - auxiliary device object.
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| 56 | * @dev: Device,
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| 57 | * The release and parent fields of the device structure must be filled
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| 58 | * in
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| 59 | * @name: Match name found by the auxiliary device driver,
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| 60 | * @id: unique identitier if multiple devices of the same name are exported,
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| 61 | * @sysfs: embedded struct which hold all sysfs related fields,
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| 62 | * @sysfs.irqs: irqs xarray contains irq indices which are used by the device,
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| 63 | * @sysfs.lock: Synchronize irq sysfs creation,
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| 64 | * @sysfs.irq_dir_exists: whether "irqs" directory exists,
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| 65 | * @registration_data_rust: private data owned by the registering (parent)
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| 66 | * driver; valid for as long as the device is
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| 67 | * registered with the driver core,
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| 68 | *
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| 69 | * An auxiliary_device represents a part of its parent device's functionality.
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| 70 | * It is given a name that, combined with the registering drivers
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| 71 | * KBUILD_MODNAME, creates a match_name that is used for driver binding, and an
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| 72 | * id that combined with the match_name provide a unique name to register with
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| 73 | * the bus subsystem. For example, a driver registering an auxiliary device is
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| 74 | * named 'foo_mod.ko' and the subdevice is named 'foo_dev'. The match name is
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| 75 | * therefore 'foo_mod.foo_dev'.
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| 76 | *
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| 77 | * Registering an auxiliary_device is a three-step process.
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| 78 | *
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| 79 | * First, a 'struct auxiliary_device' needs to be defined or allocated for each
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| 80 | * sub-device desired. The name, id, dev.release, and dev.parent fields of
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| 81 | * this structure must be filled in as follows.
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| 82 | *
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| 83 | * The 'name' field is to be given a name that is recognized by the auxiliary
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| 84 | * driver. If two auxiliary_devices with the same match_name, eg
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| 85 | * "foo_mod.foo_dev", are registered onto the bus, they must have unique id
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| 86 | * values (e.g. "x" and "y") so that the registered devices names are
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| 87 | * "foo_mod.foo_dev.x" and "foo_mod.foo_dev.y". If match_name + id are not
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| 88 | * unique, then the device_add fails and generates an error message.
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| 89 | *
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| 90 | * The auxiliary_device.dev.type.release or auxiliary_device.dev.release must
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| 91 | * be populated with a non-NULL pointer to successfully register the
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| 92 | * auxiliary_device. This release call is where resources associated with the
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| 93 | * auxiliary device must be free'ed. Because once the device is placed on the
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| 94 | * bus the parent driver can not tell what other code may have a reference to
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| 95 | * this data.
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| 96 | *
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| 97 | * The auxiliary_device.dev.parent should be set. Typically to the registering
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| 98 | * drivers device.
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| 99 | *
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| 100 | * Second, call auxiliary_device_init(), which checks several aspects of the
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| 101 | * auxiliary_device struct and performs a device_initialize(). After this step
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| 102 | * completes, any error state must have a call to auxiliary_device_uninit() in
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| 103 | * its resolution path.
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| 104 | *
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| 105 | * The third and final step in registering an auxiliary_device is to perform a
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| 106 | * call to auxiliary_device_add(), which sets the name of the device and adds
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| 107 | * the device to the bus.
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| 108 | *
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| 109 | * .. code-block:: c
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| 110 | *
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| 111 | * #define MY_DEVICE_NAME "foo_dev"
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| 112 | *
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| 113 | * ...
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| 114 | *
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| 115 | * struct auxiliary_device *my_aux_dev = my_aux_dev_alloc(xxx);
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| 116 | *
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| 117 | * // Step 1:
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| 118 | * my_aux_dev->name = MY_DEVICE_NAME;
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| 119 | * my_aux_dev->id = my_unique_id_alloc(xxx);
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| 120 | * my_aux_dev->dev.release = my_aux_dev_release;
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| 121 | * my_aux_dev->dev.parent = my_dev;
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| 122 | *
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| 123 | * // Step 2:
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| 124 | * if (auxiliary_device_init(my_aux_dev))
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| 125 | * goto fail;
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| 126 | *
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| 127 | * // Step 3:
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| 128 | * if (auxiliary_device_add(my_aux_dev)) {
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| 129 | * auxiliary_device_uninit(my_aux_dev);
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| 130 | * goto fail;
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| 131 | * }
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| 132 | *
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| 133 | * ...
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| 134 | *
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| 135 | *
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| 136 | * Unregistering an auxiliary_device is a two-step process to mirror the
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| 137 | * register process. First call auxiliary_device_delete(), then call
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| 138 | * auxiliary_device_uninit().
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| 139 | *
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| 140 | * .. code-block:: c
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| 141 | *
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| 142 | * auxiliary_device_delete(my_dev->my_aux_dev);
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| 143 | * auxiliary_device_uninit(my_dev->my_aux_dev);
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| 144 |
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| 145 | struct auxiliary_device {
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| 146 | struct device dev;
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| 147 | const char *name;
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| 148 | u32 id;
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| 149 | struct {
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| 150 | struct xarray irqs;
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| 151 | struct mutex lock;
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| 152 | bool irq_dir_exists;
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| 153 | } sysfs;
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| 154 | void *registration_data_rust;
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| 155 | };
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| 156 |
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| 157 | |
| 158 | * struct auxiliary_driver - Definition of an auxiliary bus driver
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| 159 | * @probe: Called when a matching device is added to the bus.
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| 160 | * @remove: Called when device is removed from the bus.
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| 161 | * @shutdown: Called at shut-down time to quiesce the device.
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| 162 | * @suspend: Called to put the device to sleep mode. Usually to a power state.
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| 163 | * @resume: Called to bring a device from sleep mode.
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| 164 | * @name: Driver name.
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| 165 | * @driver: Core driver structure.
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| 166 | * @id_table: Table of devices this driver should match on the bus.
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| 167 | *
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| 168 | * Auxiliary drivers follow the standard driver model convention, where
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| 169 | * discovery/enumeration is handled by the core, and drivers provide probe()
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| 170 | * and remove() methods. They support power management and shutdown
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| 171 | * notifications using the standard conventions.
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| 172 | *
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| 173 | * Auxiliary drivers register themselves with the bus by calling
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| 174 | * auxiliary_driver_register(). The id_table contains the match_names of
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| 175 | * auxiliary devices that a driver can bind with.
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| 176 | *
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| 177 | * .. code-block:: c
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| 178 | *
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| 179 | * static const struct auxiliary_device_id my_auxiliary_id_table[] = {
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| 180 | * { .name = "foo_mod.foo_dev" },
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| 181 | * {},
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| 182 | * };
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| 183 | *
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| 184 | * MODULE_DEVICE_TABLE(auxiliary, my_auxiliary_id_table);
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| 185 | *
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| 186 | * struct auxiliary_driver my_drv = {
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| 187 | * .name = "myauxiliarydrv",
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| 188 | * .id_table = my_auxiliary_id_table,
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| 189 | * .probe = my_drv_probe,
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| 190 | * .remove = my_drv_remove
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| 191 | * };
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| 192 |
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| 193 | struct auxiliary_driver {
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| 194 | int (*probe)(struct auxiliary_device *auxdev, const struct auxiliary_device_id *id);
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| 195 | void (*remove)(struct auxiliary_device *auxdev);
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| 196 | void (*shutdown)(struct auxiliary_device *auxdev);
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| 197 | int (*suspend)(struct auxiliary_device *auxdev, pm_message_t state);
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| 198 | int (*resume)(struct auxiliary_device *auxdev);
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| 199 | const char *name;
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| 200 | struct device_driver driver;
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| 201 | const struct auxiliary_device_id *id_table;
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| 202 | };
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| 203 |
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| 204 | static inline void *auxiliary_get_drvdata(struct auxiliary_device *auxdev)
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| 205 | {
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| 206 | return dev_get_drvdata(&auxdev->dev);
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| 207 | }
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| 208 |
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| 209 | static inline void auxiliary_set_drvdata(struct auxiliary_device *auxdev, void *data)
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| 210 | {
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| 211 | dev_set_drvdata(&auxdev->dev, data);
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| 212 | }
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| 213 |
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| 214 | static inline struct auxiliary_device *to_auxiliary_dev(struct device *dev)
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| 215 | {
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| 216 | return container_of(dev, struct auxiliary_device, dev);
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| 217 | }
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| 218 |
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| 219 | static inline const struct auxiliary_driver *to_auxiliary_drv(const struct device_driver *drv)
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| 220 | {
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| 221 | return container_of(drv, struct auxiliary_driver, driver);
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| 222 | }
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| 223 |
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| 224 | int auxiliary_device_init(struct auxiliary_device *auxdev);
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| 225 | int __auxiliary_device_add(struct auxiliary_device *auxdev, const char *modname);
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| 226 | #define auxiliary_device_add(auxdev) __auxiliary_device_add(auxdev, KBUILD_MODNAME)
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| 227 |
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| 228 | #ifdef CONFIG_SYSFS
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| 229 | int auxiliary_device_sysfs_irq_add(struct auxiliary_device *auxdev, int irq);
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| 230 | void auxiliary_device_sysfs_irq_remove(struct auxiliary_device *auxdev,
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| 231 | int irq);
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| 232 | #else
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| 233 | static inline int
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| 234 | auxiliary_device_sysfs_irq_add(struct auxiliary_device *auxdev, int irq)
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| 235 | {
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| 236 | return 0;
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| 237 | }
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| 238 |
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| 239 | static inline void
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| 240 | auxiliary_device_sysfs_irq_remove(struct auxiliary_device *auxdev, int irq) {}
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| 241 | #endif
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| 242 |
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| 243 | static inline void auxiliary_device_uninit(struct auxiliary_device *auxdev)
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| 244 | {
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| 245 | mutex_destroy(&auxdev->sysfs.lock);
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| 246 | put_device(&auxdev->dev);
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| 247 | }
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| 248 |
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| 249 | static inline void auxiliary_device_delete(struct auxiliary_device *auxdev)
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| 250 | {
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| 251 | device_del(&auxdev->dev);
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| 252 | }
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| 253 |
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| 254 | int __auxiliary_driver_register(struct auxiliary_driver *auxdrv, struct module *owner,
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| 255 | const char *modname);
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| 256 | #define auxiliary_driver_register(auxdrv) \
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| 257 | __auxiliary_driver_register(auxdrv, THIS_MODULE, KBUILD_MODNAME)
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| 258 |
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| 259 | void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv);
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| 260 |
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| 261 | struct auxiliary_device *auxiliary_device_create(struct device *dev,
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| 262 | const char *modname,
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| 263 | const char *devname,
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| 264 | void *platform_data,
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| 265 | int id);
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| 266 | void auxiliary_device_destroy(void *auxdev);
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| 267 |
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| 268 | struct auxiliary_device *__devm_auxiliary_device_create(struct device *dev,
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| 269 | const char *modname,
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| 270 | const char *devname,
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| 271 | void *platform_data,
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| 272 | int id);
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| 273 |
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| 274 | #define devm_auxiliary_device_create(dev, devname, platform_data) \
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| 275 | __devm_auxiliary_device_create(dev, KBUILD_MODNAME, devname, \
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| 276 | platform_data, 0)
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| 277 |
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| 278 | bool dev_is_auxiliary(struct device *dev);
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| 279 |
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| 280 | |
| 281 | * module_auxiliary_driver() - Helper macro for registering an auxiliary driver
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| 282 | * @__auxiliary_driver: auxiliary driver struct
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| 283 | *
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| 284 | * Helper macro for auxiliary drivers which do not do anything special in
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| 285 | * module init/exit. This eliminates a lot of boilerplate. Each module may only
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| 286 | * use this macro once, and calling it replaces module_init() and module_exit()
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| 287 | *
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| 288 | * .. code-block:: c
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| 289 | *
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| 290 | * module_auxiliary_driver(my_drv);
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| 291 |
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| 292 | #define module_auxiliary_driver(__auxiliary_driver) \
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| 293 | module_driver(__auxiliary_driver, auxiliary_driver_register, auxiliary_driver_unregister)
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| 294 |
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| 295 | #endif
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