• Ira Weiny's avatar
    cxl/port: Read CDAT table · c9700604
    Ira Weiny authored
    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.comSigned-off-by: default avatarDan Williams <dan.j.williams@intel.com>
    c9700604
pci.c 15.2 KB