• Tony Lindgren's avatar
    clk: ti: Add support for FAPLL on dm816x · 163152cb
    Tony Lindgren authored
    On dm816x the clocks are sourced from a FAPLL (Flying Adder PLL)
    that does not seem to be used on the other omap variants.
    
    There are four instances of the FAPLL on dm816x that each have three
    to seven child synthesizers.
    
    I've set up the FAPLL as a single fapll.c driver. Later on we could
    potentially have the PLL code generic. To do that, we would have to
    consider the following:
    
    1. Setting the PLL to bypass mode also sets the child synthesizers
       into bypass mode. As the bypass rate can also be generated by
       the PLL in regular mode, there's no way for the child synthesizers
       to detect the bypass mode based on the parent clock rate.
    
    2. The PLL registers control the power for each of the child
       syntheriser.
    
    Note that the clocks are currently still missing the set_rate
    implementation so things are still running based on the bootloader
    values. That's OK for now as most of the outputs have dividers and
    those can be set using the existing TI component clock code.
    
    I have verified that the extclk rates are correct for a few clocks,
    so adding the set_rate support should be fairly trivial later on.
    
    This code is partially based on the TI81XX-LINUX-PSP-04.04.00.02
    patches published at:
    
    http://downloads.ti.com/dsps/dsps_public_sw/psp/LinuxPSP/TI81XX_04_04/04_04_00_02/index_FDS.html
    
    Cc: Brian Hutchinson <b.hutchman@gmail.com>
    Cc: Paul Walmsley <paul@pwsan.com>
    Cc: Tero Kristo <t-kristo@ti.com>
    Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
    Signed-off-by: default avatarMichael Turquette <mturquette@linaro.org>
    163152cb
fapll.txt 1.04 KB