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![Greg Kroah-Hartman](/assets/img/avatar_default.png)
The uevent() callback in struct bus_type should not be modifying the device that is passed into it, so mark it as a const * and propagate the function signature changes out into all relevant subsystems that use this callback. Acked-by: Rafael J. Wysocki <rafael@kernel.org> Acked-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20230111113018.459199-16-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
419 lines
14 KiB
C
419 lines
14 KiB
C
// 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(const 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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