• Thomas Petazzoni's avatar
    bus: introduce an Marvell EBU MBus driver · fddddb52
    Thomas Petazzoni authored
    The Marvell EBU SoCs have a configurable physical address space
    layout: the physical ranges of memory used to address PCI(e)
    interfaces, NOR flashes, SRAM and various other types of memory are
    configurable by software, through a mechanism of so-called 'address
    decoding windows'.
    This new driver mvebu-mbus consolidates the existing code to address
    the configuration of these memory ranges, which is spread into
    mach-mvebu, mach-orion5x, mach-mv78xx0, mach-dove and mach-kirkwood.
    Following patches convert each Marvell EBU SoC family to use this
    driver, therefore removing the old code that was configuring the
    address decoding windows.
    It is worth mentioning that the MVEBU_MBUS Kconfig option is
    intentionally added as a blind option. The new driver implements and
    exports the mv_mbus_dram_info() function, which is used by various
    Marvell drivers throughout the tree to get access to window
    configuration parameters that they require. This function is also
    implemented in arch/arm/plat-orion/addr-map.c, which ultimately gets
    removed at the end of this patch series. So, in order to preserve
    bisectability, we want to ensure that *either* this new driver, *or*
    the legacy code in plat-orion/addr-map.c gets compiled in.
    By making MVEBU_MBUS a blind option, we are sure that only a platform
    that does 'select MVEBU_MBUS' will get this new driver compiled
    in. Therefore, throughout the next patches that convert the Marvell
    sub-architectures one after the other to this new driver, we add the
    'select MVEBU_MBUS' and also ensure to remove plat-orion/addr-map.c
    from the build for this specific sub-architecture. This ensures that
    bisectability is preserved.
    Ealier versions of this driver had a DT binding, but since those were
    not yet agreed upon, they were removed. The driver still uses
    of_device_id to find the SoC specific details according to the string
    passed to mvebu_mbus_init(). The plan is to re-introduce a proper DT
    binding as a followup set of patches.
    Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
    Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
    Signed-off-by: default avatarJason Cooper <jason@lakedaemon.net>