• Ray Jui's avatar
    PCI: iproc: Add iProc PCIe MSI support · 3bc2b234
    Ray Jui authored
    Add PCIe MSI support for both PAXB and PAXC interfaces on all iProc-based
    platforms.
    
    The iProc PCIe MSI support deploys an event queue-based implementation.
    Each event queue is serviced by a GIC interrupt and can support up to 64
    MSI vectors.  Host memory is allocated for the event queues, and each event
    queue consists of 64 word-sized entries.  MSI data is written to the lower
    16-bit of each entry, whereas the upper 16-bit of the entry is reserved for
    the controller for internal processing.
    
    Each event queue is tracked by a head pointer and tail pointer.  Head
    pointer indicates the next entry in the event queue to be processed by
    the driver and is updated by the driver after processing is done.
    The controller uses the tail pointer as the next MSI data insertion
    point.  The controller ensures MSI data is flushed to host memory before
    updating the tail pointer and then triggering the interrupt.
    
    MSI IRQ affinity is supported by evenly distributing the interrupts to each
    CPU core.  MSI vector is moved from one GIC interrupt to another in order
    to steer to the target CPU.
    
    Therefore, the actual number of supported MSI vectors is:
    
      M * 64 / N
    
    where M denotes the number of GIC interrupts (event queues), and N denotes
    the number of CPU cores.
    
    This iProc event queue-based MSI support should not be used with newer
    platforms with integrated MSI support in the GIC (e.g., giv2m or
    gicv3-its).
    
    [bhelgaas: fold in Kconfig fixes from Arnd Bergmann <arnd@arndb.de>]
    Signed-off-by: default avatarRay Jui <rjui@broadcom.com>
    Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
    Reviewed-by: default avatarAnup Patel <anup.patel@broadcom.com>
    Reviewed-by: default avatarVikram Prakash <vikramp@broadcom.com>
    Reviewed-by: default avatarScott Branden <sbranden@broadcom.com>
    Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
    3bc2b234
pcie-iproc-msi.c 17.5 KB