linux/Documentation/ABI/testing/sysfs-bus-platform
Barry Song 4a60406d35 driver core: platform: expose numa_node to users in sysfs
Some platform devices like ARM SMMU are memory-mapped and populated by ACPI/IORT.
In this case, NUMA topology of those platform devices are exported by firmware as
well. Software might care about the numa_node of those devices in order to achieve
NUMA locality.
This patch will show the numa_node for this kind of devices in sysfs. For those
platform devices without numa, numa_node won't be visible.

Cc: Prime Zeng <prime.zeng@hisilicon.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Link: https://lore.kernel.org/r/20200619030045.81956-1-song.bao.hua@hisilicon.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-10 14:14:37 +02:00

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What: /sys/bus/platform/devices/.../driver_override
Date: April 2014
Contact: Kim Phillips <kim.phillips@freescale.com>
Description:
This file allows the driver for a device to be specified which
will override standard OF, ACPI, ID table, and name matching.
When specified, only a driver with a name matching the value
written to driver_override will have an opportunity to bind
to the device. The override is specified by writing a string
to the driver_override file (echo vfio-platform > \
driver_override) and may be cleared with an empty string
(echo > driver_override). This returns the device to standard
matching rules binding. Writing to driver_override does not
automatically unbind the device from its current driver or make
any attempt to automatically load the specified driver. If no
driver with a matching name is currently loaded in the kernel,
the device will not bind to any driver. This also allows
devices to opt-out of driver binding using a driver_override
name such as "none". Only a single driver may be specified in
the override, there is no support for parsing delimiters.
What: /sys/bus/platform/devices/.../numa_node
Date: June 2020
Contact: Barry Song <song.bao.hua@hisilicon.com>
Description:
This file contains the NUMA node to which the platform device
is attached. It won't be visible if the node is unknown. The
value comes from an ACPI _PXM method or a similar firmware
source. Initial users for this file would be devices like
arm smmu which are populated by arm64 acpi_iort.