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    arm64: dts: qcom: sdm845: Add I2C, SPI, and UART9 nodes · 897cf34e
    Douglas Anderson 提交于
    This adds nodes to SDM845-dtsi for all the I2C ports, all the SPI
    ports, and UART9.  Note that I2C / SPI / UART are a bit strange on
    sdm845 because each "serial engine" has 4 pins associated with it and
    depending on which firmware has been loaded into the serial engine
    (loaded by the BIOS) the serial engine can behave like an I2C port, a
    SPI port, or a UART.  As per the landed bindings that means that we
    need to create one node for each possible mode that the port could be
    in.  With 16 serial engines that means 16 x 3 = 48 nodes.
    
    We get away with only creating 33 nodes for now because it seems very
    likely that SDM845-based boards will actually all use the same UART
    (UART 9) for debug purposes.  While another UART could be used for
    something like Bluetooth communication we can cross that path when we
    come to it.  Some documentation that I saw implied that using a UART
    for "high speed" communications actually needs yet another different
    serial engine firmware anyway.
    
    Note that quick measurements adding all these nodes adds <10k of extra
    space per dtb that they're included with.  If this becomes a problem
    we may need to think of a different way to structure this so that
    boards only get the nodes they need (or figure out how to get dtc to
    strip 'disabled' nodes).  For now it seems OK.
    
    These nodes were programmatically generated with a fairly dumb python
    script.  See http://crosreview.com/1091631 for the source.
    
    NOTE: at the moment SPI chip select doesn't appear to work in my tests
    with the latest posted SPI driver.  All testing of SPI with this patch
    has been done by hacking SPI to GPIO chip select.
    Signed-off-by: NDouglas Anderson <dianders@chromium.org>
    Reviewed-by: NBjorn Andersson <bjorn.andersson@linaro.org>
    Signed-off-by: NAndy Gross <andy.gross@linaro.org>
    897cf34e
sdm845.dtsi 23.8 KB