• Thomas Petazzoni's avatar
    PCI: Introduce PCI bridge emulated config space common logic · 23a5fba4
    Thomas Petazzoni authored and Lorenzo Pieralisi's avatar Lorenzo Pieralisi committed
    
    
    Some PCI host controllers do not expose a configuration space for the
    root port PCI bridge. Due to this, the Marvell Armada 370/38x/XP PCI
    controller driver (pci-mvebu) emulates a root port PCI bridge
    configuration space, and uses that to (among other things) dynamically
    create the memory windows that correspond to the PCI MEM and I/O
    regions.
    
    Since we now need to add a very similar logic for the Marvell Armada
    37xx PCI controller driver (pci-aardvark), instead of duplicating the
    code, we create in this commit a common logic called pci-bridge-emul.
    
    The idea of this logic is to emulate a root port PCI bridge
    configuration space by providing configuration space read/write
    operations, and faking behind the scenes the configuration space of a
    PCI bridge. A PCI host controller driver simply has to call
    pci_bridge_emul_conf_read() and pci_bridge_emul_conf_write() to
    read/write the configuration space of the bridge.
    
    By default, the PCI bridge configuration space is simply emulated by a
    chunk of memory, but the PCI host controller can override the behavior
    of the read and write operations on a per-register basis to do
    additional actions if needed. We take care of complying with the
    behavior of the PCI configuration space registers in terms of bits
    that are read-write, read-only, reserved and write-1-to-clear.
    Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@bootlin.com>
    Signed-off-by: Lorenzo Pieralisi's avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
    Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
    Reviewed-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
    23a5fba4