| 1 | |
| 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 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__
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| 9 |
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| 10 | #include <linux/device.h>
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| 11 | #include <linux/init.h>
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| 12 | #include <linux/slab.h>
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| 13 | #include <linux/module.h>
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| 14 | #include <linux/pm_domain.h>
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| 15 | #include <linux/pm_runtime.h>
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| 16 | #include <linux/string.h>
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| 17 | #include <linux/auxiliary_bus.h>
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| 18 | #include "base.h"
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| 19 |
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| 20 | |
| 21 | * DOC: PURPOSE
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| 22 | *
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| 23 | * In some subsystems, the functionality of the core device (PCI/ACPI/other) is
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| 24 | * too complex for a single device to be managed by a monolithic driver (e.g.
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| 25 | * Sound Open Firmware), multiple devices might implement a common intersection
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| 26 | * of functionality (e.g. NICs + RDMA), or a driver may want to export an
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| 27 | * interface for another subsystem to drive (e.g. SIOV Physical Function export
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| 28 | * Virtual Function management). A split of the functionality into child-
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| 29 | * devices representing sub-domains of functionality makes it possible to
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| 30 | * compartmentalize, layer, and distribute domain-specific concerns via a Linux
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| 31 | * device-driver model.
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| 32 | *
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| 33 | * An example for this kind of requirement is the audio subsystem where a
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| 34 | * single IP is handling multiple entities such as HDMI, Soundwire, local
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| 35 | * devices such as mics/speakers etc. The split for the core's functionality
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| 36 | * can be arbitrary or be defined by the DSP firmware topology and include
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| 37 | * hooks for test/debug. This allows for the audio core device to be minimal
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| 38 | * and focused on hardware-specific control and communication.
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| 39 | *
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| 40 | * Each auxiliary_device represents a part of its parent functionality. The
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| 41 | * generic behavior can be extended and specialized as needed by encapsulating
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| 42 | * an auxiliary_device within other domain-specific structures and the use of
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| 43 | * .ops callbacks. Devices on the auxiliary bus do not share any structures and
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| 44 | * the use of a communication channel with the parent is domain-specific.
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| 45 | *
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| 46 | * Note that ops are intended as a way to augment instance behavior within a
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| 47 | * class of auxiliary devices, it is not the mechanism for exporting common
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| 48 | * infrastructure from the parent. Consider EXPORT_SYMBOL_NS() to convey
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| 49 | * infrastructure from the parent module to the auxiliary module(s).
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| 50 |
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| 51 |
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| 52 | |
| 53 | * DOC: USAGE
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| 54 | *
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| 55 | * The auxiliary bus is to be used when a driver and one or more kernel
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| 56 | * modules, who share a common header file with the driver, need a mechanism to
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| 57 | * connect and provide access to a shared object allocated by the
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| 58 | * auxiliary_device's registering driver. The registering driver for the
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| 59 | * auxiliary_device(s) and the kernel module(s) registering auxiliary_drivers
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| 60 | * can be from the same subsystem, or from multiple subsystems.
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| 61 | *
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| 62 | * The emphasis here is on a common generic interface that keeps subsystem
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| 63 | * customization out of the bus infrastructure.
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| 64 | *
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| 65 | * One example is a PCI network device that is RDMA-capable and exports a child
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| 66 | * device to be driven by an auxiliary_driver in the RDMA subsystem. The PCI
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| 67 | * driver allocates and registers an auxiliary_device for each physical
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| 68 | * function on the NIC. The RDMA driver registers an auxiliary_driver that
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| 69 | * claims each of these auxiliary_devices. This conveys data/ops published by
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| 70 | * the parent PCI device/driver to the RDMA auxiliary_driver.
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| 71 | *
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| 72 | * Another use case is for the PCI device to be split out into multiple sub
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| 73 | * functions. For each sub function an auxiliary_device is created. A PCI sub
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| 74 | * function driver binds to such devices that creates its own one or more class
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| 75 | * devices. A PCI sub function auxiliary device is likely to be contained in a
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| 76 | * struct with additional attributes such as user defined sub function number
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| 77 | * and optional attributes such as resources and a link to the parent device.
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| 78 | * These attributes could be used by systemd/udev; and hence should be
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| 79 | * initialized before a driver binds to an auxiliary_device.
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| 80 | *
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| 81 | * A key requirement for utilizing the auxiliary bus is that there is no
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| 82 | * dependency on a physical bus, device, register accesses or regmap support.
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| 83 | * These individual devices split from the core cannot live on the platform bus
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| 84 | * as they are not physical devices that are controlled by DT/ACPI. The same
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| 85 | * argument applies for not using MFD in this scenario as MFD relies on
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| 86 | * individual function devices being physical devices.
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| 87 |
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| 88 |
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| 89 | |
| 90 | * DOC: EXAMPLE
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| 91 | *
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| 92 | * Auxiliary devices are created and registered by a subsystem-level core
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| 93 | * device that needs to break up its functionality into smaller fragments. One
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| 94 | * way to extend the scope of an auxiliary_device is to encapsulate it within a
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| 95 | * domain-specific structure defined by the parent device. This structure
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| 96 | * contains the auxiliary_device and any associated shared data/callbacks
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| 97 | * needed to establish the connection with the parent.
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| 98 | *
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| 99 | * An example is:
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| 100 | *
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| 101 | * .. code-block:: c
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| 102 | *
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| 103 | * struct foo {
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| 104 | * struct auxiliary_device auxdev;
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| 105 | * void (*connect)(struct auxiliary_device *auxdev);
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| 106 | * void (*disconnect)(struct auxiliary_device *auxdev);
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| 107 | * void *data;
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| 108 | * };
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| 109 | *
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| 110 | * The parent device then registers the auxiliary_device by calling
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| 111 | * auxiliary_device_init(), and then auxiliary_device_add(), with the pointer
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| 112 | * to the auxdev member of the above structure. The parent provides a name for
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| 113 | * the auxiliary_device that, combined with the parent's KBUILD_MODNAME,
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| 114 | * creates a match_name that is be used for matching and binding with a driver.
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| 115 | *
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| 116 | * Whenever an auxiliary_driver is registered, based on the match_name, the
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| 117 | * auxiliary_driver's probe() is invoked for the matching devices. The
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| 118 | * auxiliary_driver can also be encapsulated inside custom drivers that make
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| 119 | * the core device's functionality extensible by adding additional
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| 120 | * domain-specific ops as follows:
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| 121 | *
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| 122 | * .. code-block:: c
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| 123 | *
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| 124 | * struct my_ops {
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| 125 | * void (*send)(struct auxiliary_device *auxdev);
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| 126 | * void (*receive)(struct auxiliary_device *auxdev);
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| 127 | * };
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| 128 | *
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| 129 | *
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| 130 | * struct my_driver {
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| 131 | * struct auxiliary_driver auxiliary_drv;
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| 132 | * const struct my_ops ops;
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| 133 | * };
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| 134 | *
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| 135 | * An example of this type of usage is:
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| 136 | *
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| 137 | * .. code-block:: c
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| 138 | *
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| 139 | * const struct auxiliary_device_id my_auxiliary_id_table[] = {
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| 140 | * { .name = "foo_mod.foo_dev" },
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| 141 | * { },
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| 142 | * };
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| 143 | *
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| 144 | * const struct my_ops my_custom_ops = {
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| 145 | * .send = my_tx,
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| 146 | * .receive = my_rx,
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| 147 | * };
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| 148 | *
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| 149 | * const struct my_driver my_drv = {
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| 150 | * .auxiliary_drv = {
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| 151 | * .name = "myauxiliarydrv",
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| 152 | * .id_table = my_auxiliary_id_table,
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| 153 | * .probe = my_probe,
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| 154 | * .remove = my_remove,
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| 155 | * .shutdown = my_shutdown,
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| 156 | * },
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| 157 | * .ops = my_custom_ops,
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| 158 | * };
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| 159 | *
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| 160 | * Please note that such custom ops approach is valid, but it is hard to implement
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| 161 | * it right without global locks per-device to protect from auxiliary_drv removal
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| 162 | * during call to that ops. In addition, this implementation lacks proper module
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| 163 | * dependency, which causes to load/unload races between auxiliary parent and devices
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| 164 | * modules.
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| 165 | *
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| 166 | * The most easiest way to provide these ops reliably without needing to
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| 167 | * have a lock is to EXPORT_SYMBOL*() them and rely on already existing
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| 168 | * modules infrastructure for validity and correct dependencies chains.
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| 169 |
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| 170 |
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| 171 | static const struct auxiliary_device_id *auxiliary_match_id(const struct auxiliary_device_id *id,
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| 172 | const struct auxiliary_device *auxdev)
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| 173 | {
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| 174 | const char *auxdev_name = dev_name(&auxdev->dev);
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| 175 | const char *p = strrchr(auxdev_name, '.');
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| 176 | int match_size;
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| 177 |
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| 178 | if (!p)
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| 179 | return NULL;
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| 180 | match_size = p - auxdev_name;
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| 181 |
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| 182 | for (; id->name[0]; id++) {
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| 183 |
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| 184 | if (strlen(id->name) == match_size &&
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| 185 | !strncmp(auxdev_name, id->name, match_size))
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| 186 | return id;
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| 187 | }
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| 188 | return NULL;
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| 189 | }
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| 190 |
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| 191 | static int auxiliary_match(struct device *dev, const struct device_driver *drv)
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| 192 | {
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| 193 | struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
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| 194 | const struct auxiliary_driver *auxdrv = to_auxiliary_drv(drv);
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| 195 |
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| 196 | return !!auxiliary_match_id(auxdrv->id_table, auxdev);
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| 197 | }
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| 198 |
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| 199 | static int auxiliary_uevent(const struct device *dev, struct kobj_uevent_env *env)
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| 200 | {
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| 201 | const char *name, *p;
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| 202 |
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| 203 | name = dev_name(dev);
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| 204 | p = strrchr(name, '.');
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| 205 |
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| 206 | return add_uevent_var(env, "MODALIAS=%s%.*s", AUXILIARY_MODULE_PREFIX,
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| 207 | (int)(p - name), name);
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| 208 | }
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| 209 |
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| 210 | static int auxiliary_bus_probe(struct device *dev)
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| 211 | {
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| 212 | const struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
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| 213 | struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
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| 214 | int ret;
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| 215 |
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| 216 | ret = dev_pm_domain_attach(dev, PD_FLAG_ATTACH_POWER_ON |
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| 217 | PD_FLAG_DETACH_POWER_OFF);
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| 218 | if (ret) {
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| 219 | dev_warn(dev, "Failed to attach to PM Domain : %d\n", ret);
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| 220 | return ret;
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| 221 | }
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| 222 |
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| 223 | return auxdrv->probe(auxdev, auxiliary_match_id(auxdrv->id_table, auxdev));
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| 224 | }
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| 225 |
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| 226 | static void auxiliary_bus_remove(struct device *dev)
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| 227 | {
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| 228 | const struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
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| 229 | struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
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| 230 |
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| 231 | if (auxdrv->remove)
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| 232 | auxdrv->remove(auxdev);
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| 233 | }
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| 234 |
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| 235 | static void auxiliary_bus_shutdown(struct device *dev)
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| 236 | {
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| 237 | const struct auxiliary_driver *auxdrv = NULL;
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| 238 | struct auxiliary_device *auxdev;
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| 239 |
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| 240 | if (dev->driver) {
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| 241 | auxdrv = to_auxiliary_drv(dev->driver);
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| 242 | auxdev = to_auxiliary_dev(dev);
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| 243 | }
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| 244 |
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| 245 | if (auxdrv && auxdrv->shutdown)
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| 246 | auxdrv->shutdown(auxdev);
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| 247 | }
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| 248 |
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| 249 | static const struct bus_type auxiliary_bus_type = {
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| 250 | .name = "auxiliary",
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| 251 | .probe = auxiliary_bus_probe,
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| 252 | .remove = auxiliary_bus_remove,
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| 253 | .shutdown = auxiliary_bus_shutdown,
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| 254 | .match = auxiliary_match,
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| 255 | .uevent = auxiliary_uevent,
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| 256 | };
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| 257 |
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| 258 | |
| 259 | * auxiliary_device_init - check auxiliary_device and initialize
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| 260 | * @auxdev: auxiliary device struct
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| 261 | *
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| 262 | * This is the second step in the three-step process to register an
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| 263 | * auxiliary_device.
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| 264 | *
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| 265 | * When this function returns an error code, then the device_initialize will
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| 266 | * *not* have been performed, and the caller will be responsible to free any
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| 267 | * memory allocated for the auxiliary_device in the error path directly.
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| 268 | *
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| 269 | * It returns 0 on success. On success, the device_initialize has been
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| 270 | * performed. After this point any error unwinding will need to include a call
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| 271 | * to auxiliary_device_uninit(). In this post-initialize error scenario, a call
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| 272 | * to the device's .release callback will be triggered, and all memory clean-up
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| 273 | * is expected to be handled there.
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| 274 |
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| 275 | int auxiliary_device_init(struct auxiliary_device *auxdev)
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| 276 | {
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| 277 | struct device *dev = &auxdev->dev;
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| 278 |
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| 279 | if (!dev->parent) {
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| 280 | pr_err("auxiliary_device has a NULL dev->parent\n");
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| 281 | return -EINVAL;
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| 282 | }
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| 283 |
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| 284 | if (!auxdev->name) {
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| 285 | pr_err("auxiliary_device has a NULL name\n");
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| 286 | return -EINVAL;
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| 287 | }
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| 288 |
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| 289 | dev->bus = &auxiliary_bus_type;
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| 290 | device_initialize(&auxdev->dev);
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| 291 | mutex_init(&auxdev->sysfs.lock);
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| 292 | return 0;
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| 293 | }
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| 294 | EXPORT_SYMBOL_GPL(auxiliary_device_init);
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| 295 |
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| 296 | |
| 297 | * __auxiliary_device_add - add an auxiliary bus device
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| 298 | * @auxdev: auxiliary bus device to add to the bus
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| 299 | * @modname: name of the parent device's driver module
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| 300 | *
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| 301 | * This is the third step in the three-step process to register an
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| 302 | * auxiliary_device.
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| 303 | *
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| 304 | * This function must be called after a successful call to
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| 305 | * auxiliary_device_init(), which will perform the device_initialize. This
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| 306 | * means that if this returns an error code, then a call to
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| 307 | * auxiliary_device_uninit() must be performed so that the .release callback
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| 308 | * will be triggered to free the memory associated with the auxiliary_device.
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| 309 | *
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| 310 | * The expectation is that users will call the "auxiliary_device_add" macro so
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| 311 | * that the caller's KBUILD_MODNAME is automatically inserted for the modname
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| 312 | * parameter. Only if a user requires a custom name would this version be
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| 313 | * called directly.
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| 314 |
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| 315 | int __auxiliary_device_add(struct auxiliary_device *auxdev, const char *modname)
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| 316 | {
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| 317 | struct device *dev = &auxdev->dev;
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| 318 | int ret;
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| 319 |
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| 320 | if (!modname) {
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| 321 | dev_err(dev, "auxiliary device modname is NULL\n");
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| 322 | return -EINVAL;
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| 323 | }
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| 324 |
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| 325 | ret = dev_set_name(dev, "%s.%s.%d", modname, auxdev->name, auxdev->id);
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| 326 | if (ret) {
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| 327 | dev_err(dev, "auxiliary device dev_set_name failed: %d\n", ret);
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| 328 | return ret;
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| 329 | }
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| 330 |
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| 331 | ret = device_add(dev);
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| 332 | if (ret)
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| 333 | dev_err(dev, "adding auxiliary device failed!: %d\n", ret);
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| 334 |
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| 335 | return ret;
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| 336 | }
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| 337 | EXPORT_SYMBOL_GPL(__auxiliary_device_add);
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| 338 |
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| 339 | |
| 340 | * __auxiliary_driver_register - register a driver for auxiliary bus devices
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| 341 | * @auxdrv: auxiliary_driver structure
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| 342 | * @owner: owning module/driver
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| 343 | * @modname: KBUILD_MODNAME for parent driver
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| 344 | *
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| 345 | * The expectation is that users will call the "auxiliary_driver_register"
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| 346 | * macro so that the caller's KBUILD_MODNAME is automatically inserted for the
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| 347 | * modname parameter. Only if a user requires a custom name would this version
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| 348 | * be called directly.
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| 349 |
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| 350 | int __auxiliary_driver_register(struct auxiliary_driver *auxdrv,
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| 351 | struct module *owner, const char *modname)
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| 352 | {
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| 353 | int ret;
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| 354 |
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| 355 | if (WARN_ON(!auxdrv->probe) || WARN_ON(!auxdrv->id_table))
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| 356 | return -EINVAL;
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| 357 |
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| 358 | if (auxdrv->name)
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| 359 | auxdrv->driver.name = kasprintf(GFP_KERNEL, "%s.%s", modname,
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| 360 | auxdrv->name);
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| 361 | else
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| 362 | auxdrv->driver.name = kasprintf(GFP_KERNEL, "%s", modname);
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| 363 | if (!auxdrv->driver.name)
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| 364 | return -ENOMEM;
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| 365 |
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| 366 | auxdrv->driver.owner = owner;
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| 367 | auxdrv->driver.bus = &auxiliary_bus_type;
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| 368 | auxdrv->driver.mod_name = modname;
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| 369 |
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| 370 | ret = driver_register(&auxdrv->driver);
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| 371 | if (ret)
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| 372 | kfree(auxdrv->driver.name);
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| 373 |
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| 374 | return ret;
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| 375 | }
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| 376 | EXPORT_SYMBOL_GPL(__auxiliary_driver_register);
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| 377 |
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| 378 | |
| 379 | * auxiliary_driver_unregister - unregister a driver
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| 380 | * @auxdrv: auxiliary_driver structure
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| 381 |
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| 382 | void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv)
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| 383 | {
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| 384 | driver_unregister(&auxdrv->driver);
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| 385 | kfree(auxdrv->driver.name);
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| 386 | }
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| 387 | EXPORT_SYMBOL_GPL(auxiliary_driver_unregister);
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| 388 |
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| 389 | static void auxiliary_device_release(struct device *dev)
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| 390 | {
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| 391 | struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
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| 392 |
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| 393 | of_node_put(dev->of_node);
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| 394 | kfree(auxdev);
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| 395 | }
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| 396 |
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| 397 | |
| 398 | * auxiliary_device_create - create a device on the auxiliary bus
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| 399 | * @dev: parent device
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| 400 | * @modname: module name used to create the auxiliary driver name.
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| 401 | * @devname: auxiliary bus device name
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| 402 | * @platform_data: auxiliary bus device platform data
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| 403 | * @id: auxiliary bus device id
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| 404 | *
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| 405 | * Helper to create an auxiliary bus device.
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| 406 | * The device created matches driver 'modname.devname' on the auxiliary bus.
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| 407 |
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| 408 | struct auxiliary_device *auxiliary_device_create(struct device *dev,
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| 409 | const char *modname,
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| 410 | const char *devname,
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| 411 | void *platform_data,
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| 412 | int id)
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| 413 | {
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| 414 | struct auxiliary_device *auxdev;
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| 415 | int ret;
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| 416 |
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| 417 | auxdev = kzalloc_obj(*auxdev);
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| 418 | if (!auxdev)
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| 419 | return NULL;
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| 420 |
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| 421 | auxdev->id = id;
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| 422 | auxdev->name = devname;
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| 423 | auxdev->dev.parent = dev;
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| 424 | auxdev->dev.platform_data = platform_data;
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| 425 | auxdev->dev.release = auxiliary_device_release;
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| 426 | device_set_of_node_from_dev(&auxdev->dev, dev);
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| 427 |
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| 428 | ret = auxiliary_device_init(auxdev);
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| 429 | if (ret) {
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| 430 | of_node_put(auxdev->dev.of_node);
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| 431 | kfree(auxdev);
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| 432 | return NULL;
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| 433 | }
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| 434 |
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| 435 | ret = __auxiliary_device_add(auxdev, modname);
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| 436 | if (ret) {
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| 437 | |
| 438 | * It may look odd but auxdev should not be freed here.
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| 439 | * auxiliary_device_uninit() calls device_put() which call
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| 440 | * the device release function, freeing auxdev.
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| 441 |
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| 442 | auxiliary_device_uninit(auxdev);
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| 443 | return NULL;
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| 444 | }
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| 445 |
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| 446 | return auxdev;
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| 447 | }
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| 448 | EXPORT_SYMBOL_GPL(auxiliary_device_create);
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| 449 |
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| 450 | |
| 451 | * auxiliary_device_destroy - remove an auxiliary device
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| 452 | * @auxdev: pointer to the auxdev to be removed
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| 453 | *
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| 454 | * Helper to remove an auxiliary device created with
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| 455 | * auxiliary_device_create()
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| 456 |
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| 457 | void auxiliary_device_destroy(void *auxdev)
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| 458 | {
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| 459 | struct auxiliary_device *_auxdev = auxdev;
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| 460 |
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| 461 | auxiliary_device_delete(_auxdev);
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| 462 | auxiliary_device_uninit(_auxdev);
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| 463 | }
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| 464 | EXPORT_SYMBOL_GPL(auxiliary_device_destroy);
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| 465 |
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| 466 | |
| 467 | * __devm_auxiliary_device_create - create a managed device on the auxiliary bus
|
| 468 | * @dev: parent device
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| 469 | * @modname: module name used to create the auxiliary driver name.
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| 470 | * @devname: auxiliary bus device name
|
| 471 | * @platform_data: auxiliary bus device platform data
|
| 472 | * @id: auxiliary bus device id
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| 473 | *
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| 474 | * Device managed helper to create an auxiliary bus device.
|
| 475 | * The device created matches driver 'modname.devname' on the auxiliary bus.
|
| 476 |
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| 477 | struct auxiliary_device *__devm_auxiliary_device_create(struct device *dev,
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| 478 | const char *modname,
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| 479 | const char *devname,
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| 480 | void *platform_data,
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| 481 | int id)
|
| 482 | {
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| 483 | struct auxiliary_device *auxdev;
|
| 484 | int ret;
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| 485 |
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| 486 | auxdev = auxiliary_device_create(dev, modname, devname, platform_data, id);
|
| 487 | if (!auxdev)
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| 488 | return NULL;
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| 489 |
|
| 490 | ret = devm_add_action_or_reset(dev, auxiliary_device_destroy,
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| 491 | auxdev);
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| 492 | if (ret)
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| 493 | return NULL;
|
| 494 |
|
| 495 | return auxdev;
|
| 496 | }
|
| 497 | EXPORT_SYMBOL_GPL(__devm_auxiliary_device_create);
|
| 498 |
|
| 499 | |
| 500 | * dev_is_auxiliary - check if the device is an auxiliary one
|
| 501 | * @dev: device to check
|
| 502 |
|
| 503 | bool dev_is_auxiliary(struct device *dev)
|
| 504 | {
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| 505 | return dev->bus == &auxiliary_bus_type;
|
| 506 | }
|
| 507 | EXPORT_SYMBOL_GPL(dev_is_auxiliary);
|
| 508 |
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| 509 | void __init auxiliary_bus_init(void)
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| 510 | {
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| 511 | WARN_ON(bus_register(&auxiliary_bus_type));
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| 512 | }
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