Those reset values have been extracted from a Raspberry Pi 3 model B
v1.2, using the 2020-08-20 version of raspios. The dump was done using
the debugfs interface of the CPRMAN driver in Linux (under
'/sys/kernel/debug/clk'). Each exposed clock tree stage (PLLs, channels
and muxes) can be observed by reading the 'regdump' file (e.g.
'plla/regdump').
Those values are set by the Raspberry Pi firmware at boot time (Linux
expects them to be set when it boots up).
Some stages are not exposed by the Linux driver (e.g. the PLL B). For
those, the reset values are unknown and left to 0 which implies a
disabled output.
Once booted in QEMU, the final clock tree is very similar to the one
visible on real hardware. The differences come from some unimplemented
devices for which the driver simply disable the corresponding clock.
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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