Skip to content
Commit c9700604 authored by Ira Weiny's avatar Ira Weiny Committed by Dan Williams
Browse files

cxl/port: Read CDAT table

The per-device CDAT data provides performance data that is relevant for
mapping which CXL devices can participate in which CXL ranges by QTG
(QoS Throttling Group) (per ECN: CXL 2.0 CEDT CFMWS & QTG_DSM) [1]. The
QTG association specified in the ECN is advisory. Until the
cxl_acpi driver grows support for invoking the QTG _DSM method the CDAT
data is only of interest to userspace that may need it for debug
purposes.

Search the DOE mailboxes available, query CDAT data, cache the data and
make it available via a sysfs binary attribute per endpoint at:

/sys/bus/cxl/devices/endpointX/CDAT

...similar to other ACPI-structured table data in
/sys/firmware/ACPI/tables. The CDAT is relative to 'struct cxl_port'
objects since switches in addition to endpoints can host a CDAT
instance. Switch CDAT support is not implemented.

This does not support table updates at runtime. It will always provide
whatever was there when first cached. It is also the case that table
updates are not expected outside of explicit DPA address map affecting
commands like Set Partition with the immediate flag set. Given that the
driver does not support Set Partition with the immediate flag set there
is no current need for update support.

Link: https://www.computeexpresslink.org/spec-landing

 [1]
Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Co-developed-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: default avatarIra Weiny <ira.weiny@intel.com>
[djbw: drop in-kernel parsing infra for now, and other minor fixups]
Reviewed-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20220719205249.566684-7-ira.weiny@intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 9d6794fe
Loading
Loading
Loading
Loading
0% Loading or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment