Commit 2e4986cf authored Feb 27, 2025 by Jason Gunthorpe

fwctl: Add basic structure for a class subsystem with a cdev

Create the class, character device and functions for a fwctl driver to
un/register to the subsystem.

A typical fwctl driver has a sysfs presence like:

$ ls -l /dev/fwctl/fwctl0
crw------- 1 root root 250, 0 Apr 25 19:16 /dev/fwctl/fwctl0

$ ls /sys/class/fwctl/fwctl0
dev  device  power  subsystem  uevent

$ ls /sys/class/fwctl/fwctl0/device/infiniband/
ibp0s10f0

$ ls /sys/class/infiniband/ibp0s10f0/device/fwctl/
fwctl0/

$ ls /sys/devices/pci0000:00/0000:00:0a.0/fwctl/fwctl0
dev  device  power  subsystem  uevent

Which allows userspace to link all the multi-subsystem driver components
together and learn the subsystem specific names for the device's
components.

Link: https://patch.msgid.link/r/1-v5-642aa0c94070+4447f-fwctl_jgg@nvidia.com


Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Tested-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

parent 2014c95a

MAINTAINERS

+9 −0

Original line number	Diff line number	Diff line
		@@ -9557,6 +9557,15 @@ F: kernel/futex/*
		F: tools/perf/bench/futex*
		F: tools/testing/selftests/futex/

		FWCTL SUBSYSTEM
		M: Dave Jiang <dave.jiang@intel.com>
		M: Jason Gunthorpe <jgg@nvidia.com>
		M: Saeed Mahameed <saeedm@nvidia.com>
		R: Jonathan Cameron <Jonathan.Cameron@huawei.com>
		S: Maintained
		F: drivers/fwctl/
		F: include/linux/fwctl.h

		GALAXYCORE GC0308 CAMERA SENSOR DRIVER
		M: Sebastian Reichel <sre@kernel.org>
		L: linux-media@vger.kernel.org

drivers/Kconfig

+2 −0

Original line number	Diff line number	Diff line
		@@ -21,6 +21,8 @@ source "drivers/connector/Kconfig"

		source "drivers/firmware/Kconfig"

		source "drivers/fwctl/Kconfig"

		source "drivers/gnss/Kconfig"

		source "drivers/mtd/Kconfig"

drivers/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -135,6 +135,7 @@ obj-y += ufs/
		obj-$(CONFIG_MEMSTICK) += memstick/
		obj-$(CONFIG_INFINIBAND) += infiniband/
		obj-y += firmware/
		obj-$(CONFIG_FWCTL) += fwctl/
		obj-$(CONFIG_CRYPTO) += crypto/
		obj-$(CONFIG_SUPERH) += sh/
		obj-y += clocksource/

drivers/fwctl/Kconfig

0 → 100644

+9 −0

Original line number	Diff line number	Diff line
		# SPDX-License-Identifier: GPL-2.0-only
		menuconfig FWCTL
		tristate "fwctl device firmware access framework"
		help
		fwctl provides a userspace API for restricted access to communicate
		with on-device firmware. The communication channel is intended to
		support a wide range of lockdown compatible device behaviors including
		manipulating device FLASH, debugging, and other activities that don't
		fit neatly into an existing subsystem.

drivers/fwctl/Makefile

0 → 100644

+4 −0

Original line number	Diff line number	Diff line
		# SPDX-License-Identifier: GPL-2.0
		obj-$(CONFIG_FWCTL) += fwctl.o

		fwctl-y += main.o