• Chen-Yu Tsai's avatar
    clk: sunxi-ng: Add driver for A83T CCU · 05359be1
    Chen-Yu Tsai authored
    The A83T clock control unit is a hybrid of some new style clock designs
    from the A80, and old style layout from the other Allwinner SoCs.
    
    Like the A80, the SoC does not have a low speed 32.768 kHz oscillator.
    Unlike the A80, there is no clock input either. The only low speed clock
    available is the internal oscillator which runs at around 16 MHz,
    divided by 512, yielding a low speed clock around 31.250 kHz.
    
    Also, the MMC2 module clock supports switching to a "new timing" mode.
    This mode divides the clock output by half, and disables the CCU based
    clock delays. The MMC controller must be configure to the same mode,
    and then use its internal clock delays.
    
    This driver does not support runtime switching of the timing modes.
    Instead, the new timing mode is enforced at probe time. Consumers can
    check which mode is active by trying to get the current phase delay
    of the MMC2 phase clocks, which will return -ENOTSUPP if the new
    timing mode is active.
    Signed-off-by: default avatarChen-Yu Tsai <wens@csie.org>
    Signed-off-by: default avatarMaxime Ripard <maxime.ripard@free-electrons.com>
    05359be1
sun8i-a83t-ccu.h 3.18 KB