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cpufreq: qcom-hw: Implement CPRh aware OSM programming

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On new SoCs (SDM845 onwards) the Operating State Manager (OSM) is
being programmed in the bootloader and write-protected by the
hypervisor, leaving to the OS read-only access to some of its
registers (in order to read the Lookup Tables and also some
status registers) and write access to the p-state register, for
for the OS to request a specific performance state to trigger a
DVFS switch on the CPU through the OSM hardware.

On old SoCs though (MSM8998, SDM630/660 and variants), the
bootloader will *not* initialize the OSM (and the CPRh, as it
is a requirement for it) before booting the OS, making any
request to trigger a performance state change ineffective, as
the hardware doesn't have any Lookup Table, nor is storing any
parameter to trigger a DVFS switch. In this case, basically all
of the OSM registers are *not* write protected for the OS, even
though some are - but write access is granted through SCM calls.

This commit introduces support for OSM programming, which has to
be done on these old SoCs that were distributed (almost?) always
with a bootloader that does not do any CPRh nor OSM init before
booting the kernel.
In order to program the OSM on these SoCs, it is necessary to
fullfill a "special" requirement: the Core Power Reduction
Hardened (CPRh) hardware block must be initialized, as the OSM
is "talking" to it in order to perform the Voltage part of DVFS;
here, we are calling initialization of this through Linux generic
power domains, specifically by requesting a genpd attach from the
qcom-cpufreq-hw driver, which will give back voltages associated
to each CPU frequency that has been declared in the OPPs, scaled
and interpolated with the previous one, and will also give us
parameters for the Array Power Mux (APM) and mem-acc, in order
for this driver to be then able to generate the Lookup Tables
that will be finally programmed to the OSM hardware.

After writing the parameters to the OSM and enabling it, all the
programming work will never happen anymore until a OS reboot, so
all of the allocations and "the rest" will be disposed-of: this
is done mainly to leave the code that was referred only to the
new SoCs intact, as to also emphasize on the fact that the OSM
HW is, in the end, the exact same; apart some register offsets
that are slightly different, the entire logic is the same.

This also adds the parameters to support CPU scaling on SDM630
and MSM8998.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
[Fixup for 5.18 by Jami]
This commit is contained in:
AngeloGioacchino Del Regno 2021-06-17 22:42:25 +02:00 • committed by Jami Kettunen
parent cec8ad3aa2
commit a1bb9aa9f0
1 changed files with 1057 additions and 21 deletions
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drivers/cpufreq/qcom-cpufreq-hw.c
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