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419 lines
14 KiB
419 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright (c) 2019-2020 Intel Corporation |
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* |
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* Please see Documentation/driver-api/auxiliary_bus.rst for more information. |
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*/ |
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#define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ |
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#include <linux/device.h> |
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#include <linux/init.h> |
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#include <linux/slab.h> |
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#include <linux/module.h> |
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#include <linux/pm_domain.h> |
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#include <linux/pm_runtime.h> |
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#include <linux/string.h> |
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#include <linux/auxiliary_bus.h> |
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#include "base.h" |
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/** |
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* DOC: PURPOSE |
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* |
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* In some subsystems, the functionality of the core device (PCI/ACPI/other) is |
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* too complex for a single device to be managed by a monolithic driver (e.g. |
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* Sound Open Firmware), multiple devices might implement a common intersection |
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* of functionality (e.g. NICs + RDMA), or a driver may want to export an |
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* interface for another subsystem to drive (e.g. SIOV Physical Function export |
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* Virtual Function management). A split of the functionality into child- |
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* devices representing sub-domains of functionality makes it possible to |
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* compartmentalize, layer, and distribute domain-specific concerns via a Linux |
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* device-driver model. |
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* |
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* An example for this kind of requirement is the audio subsystem where a |
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* single IP is handling multiple entities such as HDMI, Soundwire, local |
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* devices such as mics/speakers etc. The split for the core's functionality |
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* can be arbitrary or be defined by the DSP firmware topology and include |
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* hooks for test/debug. This allows for the audio core device to be minimal |
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* and focused on hardware-specific control and communication. |
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* |
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* Each auxiliary_device represents a part of its parent functionality. The |
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* generic behavior can be extended and specialized as needed by encapsulating |
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* an auxiliary_device within other domain-specific structures and the use of |
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* .ops callbacks. Devices on the auxiliary bus do not share any structures and |
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* the use of a communication channel with the parent is domain-specific. |
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* |
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* Note that ops are intended as a way to augment instance behavior within a |
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* class of auxiliary devices, it is not the mechanism for exporting common |
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* infrastructure from the parent. Consider EXPORT_SYMBOL_NS() to convey |
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* infrastructure from the parent module to the auxiliary module(s). |
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*/ |
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/** |
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* DOC: USAGE |
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* |
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* The auxiliary bus is to be used when a driver and one or more kernel |
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* modules, who share a common header file with the driver, need a mechanism to |
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* connect and provide access to a shared object allocated by the |
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* auxiliary_device's registering driver. The registering driver for the |
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* auxiliary_device(s) and the kernel module(s) registering auxiliary_drivers |
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* can be from the same subsystem, or from multiple subsystems. |
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* |
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* The emphasis here is on a common generic interface that keeps subsystem |
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* customization out of the bus infrastructure. |
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* |
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* One example is a PCI network device that is RDMA-capable and exports a child |
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* device to be driven by an auxiliary_driver in the RDMA subsystem. The PCI |
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* driver allocates and registers an auxiliary_device for each physical |
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* function on the NIC. The RDMA driver registers an auxiliary_driver that |
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* claims each of these auxiliary_devices. This conveys data/ops published by |
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* the parent PCI device/driver to the RDMA auxiliary_driver. |
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* |
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* Another use case is for the PCI device to be split out into multiple sub |
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* functions. For each sub function an auxiliary_device is created. A PCI sub |
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* function driver binds to such devices that creates its own one or more class |
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* devices. A PCI sub function auxiliary device is likely to be contained in a |
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* struct with additional attributes such as user defined sub function number |
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* and optional attributes such as resources and a link to the parent device. |
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* These attributes could be used by systemd/udev; and hence should be |
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* initialized before a driver binds to an auxiliary_device. |
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* |
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* A key requirement for utilizing the auxiliary bus is that there is no |
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* dependency on a physical bus, device, register accesses or regmap support. |
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* These individual devices split from the core cannot live on the platform bus |
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* as they are not physical devices that are controlled by DT/ACPI. The same |
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* argument applies for not using MFD in this scenario as MFD relies on |
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* individual function devices being physical devices. |
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*/ |
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/** |
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* DOC: EXAMPLE |
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* |
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* Auxiliary devices are created and registered by a subsystem-level core |
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* device that needs to break up its functionality into smaller fragments. One |
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* way to extend the scope of an auxiliary_device is to encapsulate it within a |
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* domain- pecific structure defined by the parent device. This structure |
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* contains the auxiliary_device and any associated shared data/callbacks |
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* needed to establish the connection with the parent. |
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* |
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* An example is: |
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* |
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* .. code-block:: c |
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* |
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* struct foo { |
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* struct auxiliary_device auxdev; |
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* void (*connect)(struct auxiliary_device *auxdev); |
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* void (*disconnect)(struct auxiliary_device *auxdev); |
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* void *data; |
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* }; |
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* |
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* The parent device then registers the auxiliary_device by calling |
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* auxiliary_device_init(), and then auxiliary_device_add(), with the pointer |
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* to the auxdev member of the above structure. The parent provides a name for |
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* the auxiliary_device that, combined with the parent's KBUILD_MODNAME, |
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* creates a match_name that is be used for matching and binding with a driver. |
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* |
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* Whenever an auxiliary_driver is registered, based on the match_name, the |
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* auxiliary_driver's probe() is invoked for the matching devices. The |
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* auxiliary_driver can also be encapsulated inside custom drivers that make |
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* the core device's functionality extensible by adding additional |
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* domain-specific ops as follows: |
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* |
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* .. code-block:: c |
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* |
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* struct my_ops { |
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* void (*send)(struct auxiliary_device *auxdev); |
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* void (*receive)(struct auxiliary_device *auxdev); |
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* }; |
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* |
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* |
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* struct my_driver { |
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* struct auxiliary_driver auxiliary_drv; |
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* const struct my_ops ops; |
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* }; |
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* |
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* An example of this type of usage is: |
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* |
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* .. code-block:: c |
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* |
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* const struct auxiliary_device_id my_auxiliary_id_table[] = { |
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* { .name = "foo_mod.foo_dev" }, |
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* { }, |
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* }; |
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* |
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* const struct my_ops my_custom_ops = { |
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* .send = my_tx, |
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* .receive = my_rx, |
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* }; |
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* |
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* const struct my_driver my_drv = { |
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* .auxiliary_drv = { |
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* .name = "myauxiliarydrv", |
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* .id_table = my_auxiliary_id_table, |
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* .probe = my_probe, |
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* .remove = my_remove, |
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* .shutdown = my_shutdown, |
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* }, |
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* .ops = my_custom_ops, |
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* }; |
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*/ |
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static const struct auxiliary_device_id *auxiliary_match_id(const struct auxiliary_device_id *id, |
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const struct auxiliary_device *auxdev) |
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{ |
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for (; id->name[0]; id++) { |
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const char *p = strrchr(dev_name(&auxdev->dev), '.'); |
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int match_size; |
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if (!p) |
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continue; |
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match_size = p - dev_name(&auxdev->dev); |
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/* use dev_name(&auxdev->dev) prefix before last '.' char to match to */ |
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if (strlen(id->name) == match_size && |
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!strncmp(dev_name(&auxdev->dev), id->name, match_size)) |
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return id; |
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} |
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return NULL; |
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} |
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static int auxiliary_match(struct device *dev, struct device_driver *drv) |
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{ |
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struct auxiliary_device *auxdev = to_auxiliary_dev(dev); |
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struct auxiliary_driver *auxdrv = to_auxiliary_drv(drv); |
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return !!auxiliary_match_id(auxdrv->id_table, auxdev); |
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} |
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static int auxiliary_uevent(struct device *dev, struct kobj_uevent_env *env) |
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{ |
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const char *name, *p; |
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name = dev_name(dev); |
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p = strrchr(name, '.'); |
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return add_uevent_var(env, "MODALIAS=%s%.*s", AUXILIARY_MODULE_PREFIX, |
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(int)(p - name), name); |
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} |
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static const struct dev_pm_ops auxiliary_dev_pm_ops = { |
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SET_RUNTIME_PM_OPS(pm_generic_runtime_suspend, pm_generic_runtime_resume, NULL) |
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SET_SYSTEM_SLEEP_PM_OPS(pm_generic_suspend, pm_generic_resume) |
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}; |
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static int auxiliary_bus_probe(struct device *dev) |
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{ |
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struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver); |
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struct auxiliary_device *auxdev = to_auxiliary_dev(dev); |
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int ret; |
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ret = dev_pm_domain_attach(dev, true); |
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if (ret) { |
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dev_warn(dev, "Failed to attach to PM Domain : %d\n", ret); |
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return ret; |
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} |
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ret = auxdrv->probe(auxdev, auxiliary_match_id(auxdrv->id_table, auxdev)); |
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if (ret) |
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dev_pm_domain_detach(dev, true); |
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return ret; |
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} |
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static void auxiliary_bus_remove(struct device *dev) |
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{ |
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struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver); |
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struct auxiliary_device *auxdev = to_auxiliary_dev(dev); |
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if (auxdrv->remove) |
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auxdrv->remove(auxdev); |
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dev_pm_domain_detach(dev, true); |
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} |
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static void auxiliary_bus_shutdown(struct device *dev) |
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{ |
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struct auxiliary_driver *auxdrv = NULL; |
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struct auxiliary_device *auxdev; |
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if (dev->driver) { |
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auxdrv = to_auxiliary_drv(dev->driver); |
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auxdev = to_auxiliary_dev(dev); |
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} |
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if (auxdrv && auxdrv->shutdown) |
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auxdrv->shutdown(auxdev); |
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} |
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static struct bus_type auxiliary_bus_type = { |
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.name = "auxiliary", |
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.probe = auxiliary_bus_probe, |
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.remove = auxiliary_bus_remove, |
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.shutdown = auxiliary_bus_shutdown, |
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.match = auxiliary_match, |
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.uevent = auxiliary_uevent, |
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.pm = &auxiliary_dev_pm_ops, |
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}; |
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/** |
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* auxiliary_device_init - check auxiliary_device and initialize |
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* @auxdev: auxiliary device struct |
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* |
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* This is the second step in the three-step process to register an |
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* auxiliary_device. |
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* |
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* When this function returns an error code, then the device_initialize will |
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* *not* have been performed, and the caller will be responsible to free any |
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* memory allocated for the auxiliary_device in the error path directly. |
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* |
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* It returns 0 on success. On success, the device_initialize has been |
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* performed. After this point any error unwinding will need to include a call |
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* to auxiliary_device_uninit(). In this post-initialize error scenario, a call |
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* to the device's .release callback will be triggered, and all memory clean-up |
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* is expected to be handled there. |
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*/ |
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int auxiliary_device_init(struct auxiliary_device *auxdev) |
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{ |
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struct device *dev = &auxdev->dev; |
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if (!dev->parent) { |
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pr_err("auxiliary_device has a NULL dev->parent\n"); |
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return -EINVAL; |
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} |
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if (!auxdev->name) { |
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pr_err("auxiliary_device has a NULL name\n"); |
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return -EINVAL; |
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} |
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dev->bus = &auxiliary_bus_type; |
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device_initialize(&auxdev->dev); |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(auxiliary_device_init); |
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/** |
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* __auxiliary_device_add - add an auxiliary bus device |
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* @auxdev: auxiliary bus device to add to the bus |
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* @modname: name of the parent device's driver module |
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* |
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* This is the third step in the three-step process to register an |
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* auxiliary_device. |
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* |
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* This function must be called after a successful call to |
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* auxiliary_device_init(), which will perform the device_initialize. This |
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* means that if this returns an error code, then a call to |
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* auxiliary_device_uninit() must be performed so that the .release callback |
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* will be triggered to free the memory associated with the auxiliary_device. |
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* |
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* The expectation is that users will call the "auxiliary_device_add" macro so |
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* that the caller's KBUILD_MODNAME is automatically inserted for the modname |
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* parameter. Only if a user requires a custom name would this version be |
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* called directly. |
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*/ |
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int __auxiliary_device_add(struct auxiliary_device *auxdev, const char *modname) |
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{ |
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struct device *dev = &auxdev->dev; |
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int ret; |
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if (!modname) { |
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dev_err(dev, "auxiliary device modname is NULL\n"); |
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return -EINVAL; |
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} |
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ret = dev_set_name(dev, "%s.%s.%d", modname, auxdev->name, auxdev->id); |
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if (ret) { |
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dev_err(dev, "auxiliary device dev_set_name failed: %d\n", ret); |
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return ret; |
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} |
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ret = device_add(dev); |
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if (ret) |
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dev_err(dev, "adding auxiliary device failed!: %d\n", ret); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(__auxiliary_device_add); |
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/** |
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* auxiliary_find_device - auxiliary device iterator for locating a particular device. |
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* @start: Device to begin with |
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* @data: Data to pass to match function |
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* @match: Callback function to check device |
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* |
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* This function returns a reference to a device that is 'found' |
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* for later use, as determined by the @match callback. |
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* |
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* The reference returned should be released with put_device(). |
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* |
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* The callback should return 0 if the device doesn't match and non-zero |
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* if it does. If the callback returns non-zero, this function will |
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* return to the caller and not iterate over any more devices. |
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*/ |
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struct auxiliary_device *auxiliary_find_device(struct device *start, |
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const void *data, |
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int (*match)(struct device *dev, const void *data)) |
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{ |
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struct device *dev; |
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dev = bus_find_device(&auxiliary_bus_type, start, data, match); |
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if (!dev) |
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return NULL; |
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return to_auxiliary_dev(dev); |
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} |
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EXPORT_SYMBOL_GPL(auxiliary_find_device); |
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/** |
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* __auxiliary_driver_register - register a driver for auxiliary bus devices |
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* @auxdrv: auxiliary_driver structure |
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* @owner: owning module/driver |
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* @modname: KBUILD_MODNAME for parent driver |
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* |
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* The expectation is that users will call the "auxiliary_driver_register" |
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* macro so that the caller's KBUILD_MODNAME is automatically inserted for the |
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* modname parameter. Only if a user requires a custom name would this version |
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* be called directly. |
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*/ |
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int __auxiliary_driver_register(struct auxiliary_driver *auxdrv, |
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struct module *owner, const char *modname) |
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{ |
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int ret; |
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if (WARN_ON(!auxdrv->probe) || WARN_ON(!auxdrv->id_table)) |
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return -EINVAL; |
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if (auxdrv->name) |
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auxdrv->driver.name = kasprintf(GFP_KERNEL, "%s.%s", modname, |
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auxdrv->name); |
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else |
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auxdrv->driver.name = kasprintf(GFP_KERNEL, "%s", modname); |
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if (!auxdrv->driver.name) |
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return -ENOMEM; |
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auxdrv->driver.owner = owner; |
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auxdrv->driver.bus = &auxiliary_bus_type; |
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auxdrv->driver.mod_name = modname; |
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ret = driver_register(&auxdrv->driver); |
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if (ret) |
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kfree(auxdrv->driver.name); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(__auxiliary_driver_register); |
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/** |
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* auxiliary_driver_unregister - unregister a driver |
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* @auxdrv: auxiliary_driver structure |
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*/ |
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void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv) |
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{ |
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driver_unregister(&auxdrv->driver); |
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kfree(auxdrv->driver.name); |
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} |
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EXPORT_SYMBOL_GPL(auxiliary_driver_unregister); |
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void __init auxiliary_bus_init(void) |
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{ |
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WARN_ON(bus_register(&auxiliary_bus_type)); |
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}
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