Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) =======================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) Frequently asked questions about the sunxi clock system
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) =======================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) This document contains useful bits of information that people tend to ask
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) about the sunxi clock system, as well as accompanying ASCII art when adequate.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) Q: Why is the main 24MHz oscillator gatable? Wouldn't that break the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9)    system?
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) A: The 24MHz oscillator allows gating to save power. Indeed, if gated
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12)    carelessly the system would stop functioning, but with the right
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13)    steps, one can gate it and keep the system running. Consider this
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14)    simplified suspend example:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16)    While the system is operational, you would see something like::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)       24MHz         32kHz
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)        |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)       PLL1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21)        \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22)         \_ CPU Mux
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)              |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24)            [CPU]
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26)    When you are about to suspend, you switch the CPU Mux to the 32kHz
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27)    oscillator::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29)       24Mhz         32kHz
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)        |              |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31)       PLL1            |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32)                      /
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33)            CPU Mux _/
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)              |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35)            [CPU]
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37)     Finally you can gate the main oscillator::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39)                     32kHz
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40)                       |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41)                       |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42)                      /
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)            CPU Mux _/
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44)              |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45)            [CPU]
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) Q: Were can I learn more about the sunxi clocks?
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) A: The linux-sunxi wiki contains a page documenting the clock registers,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50)    you can find it at
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52)         http://linux-sunxi.org/A10/CCM
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54)    The authoritative source for information at this time is the ccmu driver
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55)    released by Allwinner, you can find it at
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57)         https://github.com/linux-sunxi/linux-sunxi/tree/sunxi-3.0/arch/arm/mach-sun4i/clock/ccmu