• Serge Semin's avatar
    spi: dw: Add DWC SSI capability · d6bbd119
    Serge Semin authored
    Currently DWC SSI core is supported by means of setting up the
    core-specific update_cr0() callback. It isn't suitable for multiple
    reasons. First of all having exported several methods doing the same thing
    but for different chips makes the code harder to maintain. Secondly the
    spi-dw-core driver exports the methods, then the spi-dw-mmio driver sets
    the private data callback with one of them so to be called by the core
    driver again. That makes the code logic too complicated. Thirdly using
    callbacks for just updating the CR0 register is problematic, since in case
    if the register needed to be updated from different parts of the code,
    we'd have to create another callback (for instance the SPI device-specific
    parameters don't need to be calculated each time the SPI transfer is
    submitted, so it's better to pre-calculate the CR0 data at the SPI-device
    setup stage).
    
    So keeping all the above in mind let's discard the update_cr0() callbacks,
    define a generic and static dw_spi_update_cr0() method and create the
    DW_SPI_CAP_DWC_SSI capability, which when enabled would activate the
    alternative CR0 register layout.
    
    While at it add the comments to the code path of the normal DW APB SSI
    controller setup to make the dw_spi_update_cr0() method looking coherent.
    Signed-off-by: default avatarSerge Semin <Sergey.Semin@baikalelectronics.ru>
    Link: https://lore.kernel.org/r/20201007235511.4935-3-Sergey.Semin@baikalelectronics.ruSigned-off-by: default avatarMark Brown <broonie@kernel.org>
    d6bbd119
spi-dw-mmio.c 9.56 KB