add support for clocks on MT7981 SoC

The MediaTek MT7981 SoC is quite similar to its big sibling, the MT7986. Hence most drivers can be reused and not much is missing the get also this SoC working on mainline Linux.

Start with a cleaned-up version of the clock drivers, based on what can also be found in MediaTek's SDK[1].

Upon request of AngeloGioacchino Del Regno this series has been rebased and adapted to be applied on top of the pending series "MediaTek clocks cleanups and improvements"[2]

The complete tree used for testing (with still some to-be-cleaned-up changes, esp. for the Ethernet driver) can be found on Github[3].

[1]: https://git01.mediatek.com/plugins/gitiles/openwrt/feeds/mtk-openwrt-feeds/+/refs/heads/master/target/linux/mediatek/files-5.4/drivers/clk/mediatek/clk-mt7981.c
[2]: https://patchwork.kernel.org/project/linux-clk/list/?series=714057
[3]: https://github.com/dangowrt/linux

Changes since v4:
* add compatible string also for 'mediatek,apmixedsys', 'mediatek,ethsys' as well as 'mediatek,sgmiisys' bindings

Changes since v3:
* fixed typos in commit descriptions

Changes since v2:
* rebase on top of next-20230120 with v4 of AngeloGioacchino's series[2]
* fix titles of dt-bindings commits (this time for real)
* convert clk-mt7981-infracfg to use mtk_clk_simple_probe
* make use of PLL_AO flag in clk-mt7981-apmixed
* convert clk-mt7981-ethsys into platform driver, also using the generic probe function, allow building as module

Changes since v1:
* rebase and adapt on top of [2]
* split-off addition of dt-bindings header, fix filename
* changed commit title as requested

Daniel Golle (3):
dt-bindings: clock: Add compatibles for MT7981
dt-bindings: clock: mediatek: add mt7981 clock IDs
clk: mediatek: add MT7981 clock support

 .../bindings/arm/mediatek/mediatek,ethsys.txt |   1 +
 .../arm/mediatek/mediatek,infracfg.yaml       |   1 +
 .../arm/mediatek/mediatek,sgmiisys.txt        |   2 +
 .../bindings/clock/mediatek,apmixedsys.yaml   |   1 +
 .../bindings/clock/mediatek,topckgen.yaml     |   1 +
 drivers/clk/mediatek/Kconfig                  |  17 +
 drivers/clk/mediatek/Makefile                 |   4 +
 drivers/clk/mediatek/clk-mt7981-apmixed.c     | 102 +++++
 drivers/clk/mediatek/clk-mt7981-eth.c         | 117 +++++
 drivers/clk/mediatek/clk-mt7981-infracfg.c    | 207 +++++++++
 drivers/clk/mediatek/clk-mt7981-topckgen.c    | 422 ++++++++++++++++++
 .../dt-bindings/clock/mediatek,mt7981-clk.h   | 215 +++++++++
 12 files changed, 1090 insertions(+)
 create mode 100644 drivers/clk/mediatek/clk-mt7981-apmixed.c
 create mode 100644 drivers/clk/mediatek/clk-mt7981-eth.c
 create mode 100644 drivers/clk/mediatek/clk-mt7981-infracfg.c
 create mode 100644 drivers/clk/mediatek/clk-mt7981-topckgen.c
 create mode 100644 include/dt-bindings/clock/mediatek,mt7981-clk.h

base-commit: 9fbee811e479aca2f3523787cae1f46553141b40

2.39.1