• Chris Metcalf's avatar
    arch/tile: introduce GXIO IORPC framework for tilegx · 37b82b5d
    Chris Metcalf authored
    The GXIO I/O RPC subsystem handles exporting I/O hardware resources to
    Linux and to applications running under Linux.
    
    For instance, memory which is made available for I/O DMA must be mapped
    by an I/O TLB; that means that such memory must be locked down by Linux,
    so that it is not swapped or otherwise reused, as long as those I/O
    TLB entries are active. Similarly, configuring direct hardware access
    introduces new validation requirements. If a user application registers
    memory, Linux must ensure that the supplied virtual addresses are valid,
    and turn them into client physical addresses. Similarly, when Linux then
    supplies those client physical addresses to the Tilera hypervisor, it
    must in turn validate those before turning them into the real physical
    addresses which are required by the hardware.
    
    To the extent that these sorts of activities were required on previous
    TILE architecture processors, they were implemented in a device-specific
    fashion. This meant that every I/O device had its own Tilera hypervisor
    driver, its own Linux driver, and in some cases its own user-level
    library support. There was a large amount of more-or-less functionally
    identical code in different places, particularly in the different Linux
    drivers. For TILE-Gx, this support has been generalized into a common
    framework, known as the I/O RPC framework or just IORPC.
    
    The two "gxio" directories (one for headers, one for sources) start
    with just a few files in each with this infrastructure commit, but
    after adding support for the on-board I/O shims for networking, PCI,
    USB, crypto, compression, I2CS, etc., there end up being about 20 files
    in each directory.
    
    More information on the IORPC framework is in the <hv/iorpc.h> header,
    included in this commit.
    Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
    37b82b5d
Makefile 2.32 KB