• Ian Munsie's avatar
    cxl: Add support for interrupts on the Mellanox CX4 · a2f67d5e
    Ian Munsie authored
    The Mellanox CX4 in cxl mode uses a hybrid interrupt model, where
    interrupts are routed from the networking hardware to the XSL using the
    MSIX table, and from there will be transformed back into an MSIX
    interrupt using the cxl style interrupts (i.e. using IVTE entries and
    ranges to map a PE and AFU interrupt number to an MSIX address).
    We want to hide the implementation details of cxl interrupts as much as
    possible. To this end, we use a special version of the MSI setup &
    teardown routines in the PHB while in cxl mode to allocate the cxl
    interrupts and configure the IVTE entries in the process element.
    This function does not configure the MSIX table - the CX4 card uses a
    custom format in that table and it would not be appropriate to fill that
    out in generic code. The rest of the functionality is similar to the
    "Full MSI-X mode" described in the CAIA, and this could be easily
    extended to support other adapters that use that mode in the future.
    The interrupts will be associated with the default context. If the
    maximum number of interrupts per context has been limited (e.g. by the
    mlx5 driver), it will automatically allocate additional kernel contexts
    to associate extra interrupts as required. These contexts will be
    started using the same WED that was used to start the default context.
    Signed-off-by: 's avatarIan Munsie <imunsie@au1.ibm.com>
    Reviewed-by: 's avatarAndrew Donnellan <andrew.donnellan@au1.ibm.com>
    Signed-off-by: 's avatarMichael Ellerman <mpe@ellerman.id.au>