diff options
| -rw-r--r-- | Documentation/driver-api/infrastructure.rst | 6 | ||||
| -rw-r--r-- | MAINTAINERS | 2 | ||||
| -rw-r--r-- | drivers/base/Makefile | 2 | ||||
| -rw-r--r-- | drivers/base/base.h | 1 | ||||
| -rw-r--r-- | drivers/base/faux.c | 232 | ||||
| -rw-r--r-- | drivers/base/init.c | 1 | ||||
| -rw-r--r-- | include/linux/device/faux.h | 69 | ||||
| -rw-r--r-- | rust/bindings/bindings_helper.h | 1 | ||||
| -rw-r--r-- | rust/kernel/faux.rs | 67 | ||||
| -rw-r--r-- | rust/kernel/lib.rs | 1 | ||||
| -rw-r--r-- | samples/rust/Kconfig | 10 | ||||
| -rw-r--r-- | samples/rust/Makefile | 1 | ||||
| -rw-r--r-- | samples/rust/rust_driver_faux.rs | 29 |
13 files changed, 421 insertions, 1 deletions
diff --git a/Documentation/driver-api/infrastructure.rst b/Documentation/driver-api/infrastructure.rst index 3d52dfdfa9fd..35e36fee4238 100644 --- a/Documentation/driver-api/infrastructure.rst +++ b/Documentation/driver-api/infrastructure.rst @@ -41,6 +41,12 @@ Device Drivers Base .. kernel-doc:: drivers/base/class.c :export: +.. kernel-doc:: include/linux/device/faux.h + :internal: + +.. kernel-doc:: drivers/base/faux.c + :export: + .. kernel-doc:: drivers/base/node.c :internal: diff --git a/MAINTAINERS b/MAINTAINERS index f9228f9b7d53..efee40ea589f 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -7108,8 +7108,10 @@ F: rust/kernel/device.rs F: rust/kernel/device_id.rs F: rust/kernel/devres.rs F: rust/kernel/driver.rs +F: rust/kernel/faux.rs F: rust/kernel/platform.rs F: samples/rust/rust_driver_platform.rs +F: samples/rust/rust_driver_faux.rs DRIVERS FOR OMAP ADAPTIVE VOLTAGE SCALING (AVS) M: Nishanth Menon <nm@ti.com> diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 7fb21768ca36..8074a10183dc 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -6,7 +6,7 @@ obj-y := component.o core.o bus.o dd.o syscore.o \ cpu.o firmware.o init.o map.o devres.o \ attribute_container.o transport_class.o \ topology.o container.o property.o cacheinfo.o \ - swnode.o + swnode.o faux.o obj-$(CONFIG_AUXILIARY_BUS) += auxiliary.o obj-$(CONFIG_DEVTMPFS) += devtmpfs.o obj-y += power/ diff --git a/drivers/base/base.h b/drivers/base/base.h index 8cf04a557bdb..0042e4774b0c 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -137,6 +137,7 @@ int hypervisor_init(void); static inline int hypervisor_init(void) { return 0; } #endif int platform_bus_init(void); +int faux_bus_init(void); void cpu_dev_init(void); void container_dev_init(void); #ifdef CONFIG_AUXILIARY_BUS diff --git a/drivers/base/faux.c b/drivers/base/faux.c new file mode 100644 index 000000000000..531e9d789ee0 --- /dev/null +++ b/drivers/base/faux.c @@ -0,0 +1,232 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2025 Greg Kroah-Hartman <gregkh@linuxfoundation.org> + * Copyright (c) 2025 The Linux Foundation + * + * A "simple" faux bus that allows devices to be created and added + * automatically to it. This is to be used whenever you need to create a + * device that is not associated with any "real" system resources, and do + * not want to have to deal with a bus/driver binding logic. It is + * intended to be very simple, with only a create and a destroy function + * available. + */ +#include <linux/err.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/string.h> +#include <linux/container_of.h> +#include <linux/device/faux.h> +#include "base.h" + +/* + * Internal wrapper structure so we can hold a pointer to the + * faux_device_ops for this device. + */ +struct faux_object { + struct faux_device faux_dev; + const struct faux_device_ops *faux_ops; +}; +#define to_faux_object(dev) container_of_const(dev, struct faux_object, faux_dev.dev) + +static struct device faux_bus_root = { + .init_name = "faux", +}; + +static int faux_match(struct device *dev, const struct device_driver *drv) +{ + /* Match always succeeds, we only have one driver */ + return 1; +} + +static int faux_probe(struct device *dev) +{ + struct faux_object *faux_obj = to_faux_object(dev); + struct faux_device *faux_dev = &faux_obj->faux_dev; + const struct faux_device_ops *faux_ops = faux_obj->faux_ops; + int ret = 0; + + if (faux_ops && faux_ops->probe) + ret = faux_ops->probe(faux_dev); + + return ret; +} + +static void faux_remove(struct device *dev) +{ + struct faux_object *faux_obj = to_faux_object(dev); + struct faux_device *faux_dev = &faux_obj->faux_dev; + const struct faux_device_ops *faux_ops = faux_obj->faux_ops; + + if (faux_ops && faux_ops->remove) + faux_ops->remove(faux_dev); +} + +static const struct bus_type faux_bus_type = { + .name = "faux", + .match = faux_match, + .probe = faux_probe, + .remove = faux_remove, +}; + +static struct device_driver faux_driver = { + .name = "faux_driver", + .bus = &faux_bus_type, + .probe_type = PROBE_FORCE_SYNCHRONOUS, +}; + +static void faux_device_release(struct device *dev) +{ + struct faux_object *faux_obj = to_faux_object(dev); + + kfree(faux_obj); +} + +/** + * faux_device_create_with_groups - Create and register with the driver + * core a faux device and populate the device with an initial + * set of sysfs attributes. + * @name: The name of the device we are adding, must be unique for + * all faux devices. + * @parent: Pointer to a potential parent struct device. If set to + * NULL, the device will be created in the "root" of the faux + * device tree in sysfs. + * @faux_ops: struct faux_device_ops that the new device will call back + * into, can be NULL. + * @groups: The set of sysfs attributes that will be created for this + * device when it is registered with the driver core. + * + * Create a new faux device and register it in the driver core properly. + * If present, callbacks in @faux_ops will be called with the device that + * for the caller to do something with at the proper time given the + * device's lifecycle. + * + * Note, when this function is called, the functions specified in struct + * faux_ops can be called before the function returns, so be prepared for + * everything to be properly initialized before that point in time. + * + * Return: + * * NULL if an error happened with creating the device + * * pointer to a valid struct faux_device that is registered with sysfs + */ +struct faux_device *faux_device_create_with_groups(const char *name, + struct device *parent, + const struct faux_device_ops *faux_ops, + const struct attribute_group **groups) +{ + struct faux_object *faux_obj; + struct faux_device *faux_dev; + struct device *dev; + int ret; + + faux_obj = kzalloc(sizeof(*faux_obj), GFP_KERNEL); + if (!faux_obj) + return NULL; + + /* Save off the callbacks so we can use them in the future */ + faux_obj->faux_ops = faux_ops; + + /* Initialize the device portion and register it with the driver core */ + faux_dev = &faux_obj->faux_dev; + dev = &faux_dev->dev; + + device_initialize(dev); + dev->release = faux_device_release; + if (parent) + dev->parent = parent; + else + dev->parent = &faux_bus_root; + dev->bus = &faux_bus_type; + dev->groups = groups; + dev_set_name(dev, "%s", name); + + ret = device_add(dev); + if (ret) { + pr_err("%s: device_add for faux device '%s' failed with %d\n", + __func__, name, ret); + put_device(dev); + return NULL; + } + + return faux_dev; +} +EXPORT_SYMBOL_GPL(faux_device_create_with_groups); + +/** + * faux_device_create - create and register with the driver core a faux device + * @name: The name of the device we are adding, must be unique for all + * faux devices. + * @parent: Pointer to a potential parent struct device. If set to + * NULL, the device will be created in the "root" of the faux + * device tree in sysfs. + * @faux_ops: struct faux_device_ops that the new device will call back + * into, can be NULL. + * + * Create a new faux device and register it in the driver core properly. + * If present, callbacks in @faux_ops will be called with the device that + * for the caller to do something with at the proper time given the + * device's lifecycle. + * + * Note, when this function is called, the functions specified in struct + * faux_ops can be called before the function returns, so be prepared for + * everything to be properly initialized before that point in time. + * + * Return: + * * NULL if an error happened with creating the device + * * pointer to a valid struct faux_device that is registered with sysfs + */ +struct faux_device *faux_device_create(const char *name, + struct device *parent, + const struct faux_device_ops *faux_ops) +{ + return faux_device_create_with_groups(name, parent, faux_ops, NULL); +} +EXPORT_SYMBOL_GPL(faux_device_create); + +/** + * faux_device_destroy - destroy a faux device + * @faux_dev: faux device to destroy + * + * Unregisters and cleans up a device that was created with a call to + * faux_device_create() + */ +void faux_device_destroy(struct faux_device *faux_dev) +{ + struct device *dev = &faux_dev->dev; + + if (!faux_dev) + return; + + device_del(dev); + + /* The final put_device() will clean up the memory we allocated for this device. */ + put_device(dev); +} +EXPORT_SYMBOL_GPL(faux_device_destroy); + +int __init faux_bus_init(void) +{ + int ret; + + ret = device_register(&faux_bus_root); + if (ret) { + put_device(&faux_bus_root); + return ret; + } + + ret = bus_register(&faux_bus_type); + if (ret) + goto error_bus; + + ret = driver_register(&faux_driver); + if (ret) + goto error_driver; + + return ret; + +error_driver: + bus_unregister(&faux_bus_type); + +error_bus: + device_unregister(&faux_bus_root); + return ret; +} diff --git a/drivers/base/init.c b/drivers/base/init.c index c4954835128c..9d2b06d65dfc 100644 --- a/drivers/base/init.c +++ b/drivers/base/init.c @@ -32,6 +32,7 @@ void __init driver_init(void) /* These are also core pieces, but must come after the * core core pieces. */ + faux_bus_init(); of_core_init(); platform_bus_init(); auxiliary_bus_init(); diff --git a/include/linux/device/faux.h b/include/linux/device/faux.h new file mode 100644 index 000000000000..9f43c0e46aa4 --- /dev/null +++ b/include/linux/device/faux.h @@ -0,0 +1,69 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2025 Greg Kroah-Hartman <gregkh@linuxfoundation.org> + * Copyright (c) 2025 The Linux Foundation + * + * A "simple" faux bus that allows devices to be created and added + * automatically to it. This is to be used whenever you need to create a + * device that is not associated with any "real" system resources, and do + * not want to have to deal with a bus/driver binding logic. It is + * intended to be very simple, with only a create and a destroy function + * available. + */ +#ifndef _FAUX_DEVICE_H_ +#define _FAUX_DEVICE_H_ + +#include <linux/container_of.h> +#include <linux/device.h> + +/** + * struct faux_device - a "faux" device + * @dev: internal struct device of the object + * + * A simple faux device that can be created/destroyed. To be used when a + * driver only needs to have a device to "hang" something off. This can be + * used for downloading firmware or other basic tasks. Use this instead of + * a struct platform_device if the device has no resources assigned to + * it at all. + */ +struct faux_device { + struct device dev; +}; +#define to_faux_device(x) container_of_const((x), struct faux_device, dev) + +/** + * struct faux_device_ops - a set of callbacks for a struct faux_device + * @probe: called when a faux device is probed by the driver core + * before the device is fully bound to the internal faux bus + * code. If probe succeeds, return 0, otherwise return a + * negative error number to stop the probe sequence from + * succeeding. + * @remove: called when a faux device is removed from the system + * + * Both @probe and @remove are optional, if not needed, set to NULL. + */ +struct faux_device_ops { + int (*probe)(struct faux_device *faux_dev); + void (*remove)(struct faux_device *faux_dev); +}; + +struct faux_device *faux_device_create(const char *name, + struct device *parent, + const struct faux_device_ops *faux_ops); +struct faux_device *faux_device_create_with_groups(const char *name, + struct device *parent, + const struct faux_device_ops *faux_ops, + const struct attribute_group **groups); +void faux_device_destroy(struct faux_device *faux_dev); + +static inline void *faux_device_get_drvdata(const struct faux_device *faux_dev) +{ + return dev_get_drvdata(&faux_dev->dev); +} + +static inline void faux_device_set_drvdata(struct faux_device *faux_dev, void *data) +{ + dev_set_drvdata(&faux_dev->dev, data); +} + +#endif /* _FAUX_DEVICE_H_ */ diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 55354e4dec14..f46cf3bb7069 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -11,6 +11,7 @@ #include <linux/blk_types.h> #include <linux/blkdev.h> #include <linux/cred.h> +#include <linux/device/faux.h> #include <linux/errname.h> #include <linux/ethtool.h> #include <linux/file.h> diff --git a/rust/kernel/faux.rs b/rust/kernel/faux.rs new file mode 100644 index 000000000000..5acc0c02d451 --- /dev/null +++ b/rust/kernel/faux.rs @@ -0,0 +1,67 @@ +// SPDX-License-Identifier: GPL-2.0-only + +//! Abstractions for the faux bus. +//! +//! This module provides bindings for working with faux devices in kernel modules. +//! +//! C header: [`include/linux/device/faux.h`] + +use crate::{bindings, device, error::code::*, prelude::*}; +use core::ptr::{addr_of_mut, null, null_mut, NonNull}; + +/// The registration of a faux device. +/// +/// This type represents the registration of a [`struct faux_device`]. When an instance of this type +/// is dropped, its respective faux device will be unregistered from the system. +/// +/// # Invariants +/// +/// `self.0` always holds a valid pointer to an initialized and registered [`struct faux_device`]. +/// +/// [`struct faux_device`]: srctree/include/linux/device/faux.h +#[repr(transparent)] +pub struct Registration(NonNull<bindings::faux_device>); + +impl Registration { + /// Create and register a new faux device with the given name. + pub fn new(name: &CStr) -> Result<Self> { + // SAFETY: + // - `name` is copied by this function into its own storage + // - `faux_ops` is safe to leave NULL according to the C API + let dev = unsafe { bindings::faux_device_create(name.as_char_ptr(), null_mut(), null()) }; + + // The above function will return either a valid device, or NULL on failure + // INVARIANT: The device will remain registered until faux_device_destroy() is called, which + // happens in our Drop implementation. + Ok(Self(NonNull::new(dev).ok_or(ENODEV)?)) + } + + fn as_raw(&self) -> *mut bindings::faux_device { + self.0.as_ptr() + } +} + +impl AsRef<device::Device> for Registration { + fn as_ref(&self) -> &device::Device { + // SAFETY: The underlying `device` in `faux_device` is guaranteed by the C API to be + // a valid initialized `device`. + unsafe { device::Device::as_ref(addr_of_mut!((*self.as_raw()).dev)) } + } +} + +impl Drop for Registration { + fn drop(&mut self) { + // SAFETY: `self.0` is a valid registered faux_device via our type invariants. + unsafe { bindings::faux_device_destroy(self.as_raw()) } + } +} + +// SAFETY: The faux device API is thread-safe as guaranteed by the device core, as long as +// faux_device_destroy() is guaranteed to only be called once - which is guaranteed by our type not +// having Copy/Clone. +unsafe impl Send for Registration {} + +// SAFETY: The faux device API is thread-safe as guaranteed by the device core, as long as +// faux_device_destroy() is guaranteed to only be called once - which is guaranteed by our type not +// having Copy/Clone. +unsafe impl Sync for Registration {} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 496ed32b0911..398242f92a96 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -46,6 +46,7 @@ pub mod device_id; pub mod devres; pub mod driver; pub mod error; +pub mod faux; #[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)] pub mod firmware; pub mod fs; diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig index 918dbead2c0b..3b6eae84b297 100644 --- a/samples/rust/Kconfig +++ b/samples/rust/Kconfig @@ -61,6 +61,16 @@ config SAMPLE_RUST_DRIVER_PLATFORM If unsure, say N. +config SAMPLE_RUST_DRIVER_FAUX + tristate "Faux Driver" + help + This option builds the Rust Faux driver sample. + + To compile this as a module, choose M here: + the module will be called rust_driver_faux. + + If unsure, say N. + config SAMPLE_RUST_HOSTPROGS bool "Host programs" help diff --git a/samples/rust/Makefile b/samples/rust/Makefile index 5a8ab0df0567..0dbc6d90f1ef 100644 --- a/samples/rust/Makefile +++ b/samples/rust/Makefile @@ -6,6 +6,7 @@ obj-$(CONFIG_SAMPLE_RUST_MISC_DEVICE) += rust_misc_device.o obj-$(CONFIG_SAMPLE_RUST_PRINT) += rust_print.o obj-$(CONFIG_SAMPLE_RUST_DRIVER_PCI) += rust_driver_pci.o obj-$(CONFIG_SAMPLE_RUST_DRIVER_PLATFORM) += rust_driver_platform.o +obj-$(CONFIG_SAMPLE_RUST_DRIVER_FAUX) += rust_driver_faux.o rust_print-y := rust_print_main.o rust_print_events.o diff --git a/samples/rust/rust_driver_faux.rs b/samples/rust/rust_driver_faux.rs new file mode 100644 index 000000000000..048c6cb98b29 --- /dev/null +++ b/samples/rust/rust_driver_faux.rs @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0-only + +//! Rust faux device sample. + +use kernel::{c_str, faux, prelude::*, Module}; + +module! { + type: SampleModule, + name: "rust_faux_driver", + author: "Lyude Paul", + description: "Rust faux device sample", + license: "GPL", +} + +struct SampleModule { + _reg: faux::Registration, +} + +impl Module for SampleModule { + fn init(_module: &'static ThisModule) -> Result<Self> { + pr_info!("Initialising Rust Faux Device Sample\n"); + + let reg = faux::Registration::new(c_str!("rust-faux-sample-device"))?; + + dev_info!(reg.as_ref(), "Hello from faux device!\n"); + + Ok(Self { _reg: reg }) + } +} |