[PATCH v2 0/3] cpufreq: Add imx-cpufreq-dt driver

[Leonard Crestez <leonard.crestez@nxp.com>]

Right now in upstream imx8m cpufreq support just lists a common subset
of OPPs because the higher ones should only be attempted after checking
speed grading in fuses.

Add a small driver which checks speed grading from nvmem cells before
registering cpufreq-dt.

---

By default kconfig builds it as a module even though it's very small.
Couldn't find a way for MODULE_DEVICE_TABLE to match on root node compat
string and there was no other appropriate node so register the
imx-cpufreq-dt platfrom device directly from imx8 soc driver instead. I
checked module is probed by default and rmmod/modprobe again works.

It seems that cpufreq-dt insists on adding the opp and regulator itself
so can't actually call dev_pm_opp_of_add_table and then
dev_pm_opp_disable so implementation was switched to opp-supported-hw.
Maybe I'm confused by API quirks?

The market segment logic was dropped because I couldn't find any good
references in datasheets for why lower or intermediary OPPs should be
disabled on certain market segments. Using opp-supported-hw means that
adding this in the future would require changing flags inside DT instead
of code, that seems undesirable for DT compat reasons.

This could also be extended to mach-imx7d speed grading.

I never noticed anything wrong with going above the fused speed grading
however it's technically unsafe so the cpufreq parts should go in before
DT changes.

Other changes since v1:
 * Turn into a proper module
 * Support imx8mq
Link to v1 (RFC): https://patchwork.kernel.org/patch/10916769/

Leonard Crestez (3):
  cpufreq: Add imx-cpufreq-dt driver
  arm64: dts: imx8mm: Add cpu speed grading and all OPPs
  arm64: dts: imx8mq: Add cpu speed grading and all OPPs

 arch/arm64/boot/dts/freescale/imx8mm.dtsi | 23 +++++-
 arch/arm64/boot/dts/freescale/imx8mq.dtsi | 23 +++++-
 drivers/cpufreq/Kconfig.arm               | 10 +++
 drivers/cpufreq/Makefile                  |  1 +
 drivers/cpufreq/cpufreq-dt-platdev.c      |  3 +
 drivers/cpufreq/imx-cpufreq-dt.c          | 99 +++++++++++++++++++++++
 drivers/soc/imx/soc-imx8.c                |  3 +
 7 files changed, 160 insertions(+), 2 deletions(-)
 create mode 100644 drivers/cpufreq/imx-cpufreq-dt.c

-- 
2.17.1

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