Add iMX8MQ support

[gonzo]

Summary

This patch adds basic support for for iMX8:

• CCM driver and clocks implementations for iMX8
• GPC driver for iMX8
• clock tree for iMX8MQ
• clocks support and new compat strings (if required) for existing iMX6 UART, I2C, and GPIO drivers
• Enables aarch64-compatible drivers form iMX6 to arm64 GENERIC kernel config
• dtb/imx8 kernel module with DTBs for Nitrogen8M and iMX8MQ EVK

Test Plan

This patch was tested only for basic functionality:

• Booted on Nitrogen8M board with NFS root
• Booted on iMX8MQ EVK board with NFS root
• watchdog tested with watchdogd -t 33 -e /usr/bin/false --debug
• I2C tested by scanning the bus and checking that there is device
• GPIO wasn't tested

Also verified that both GENERIC and IMX6 kernel configs still build
and boot with this patch applied.

[manu]

Added a few nits but otherwise it's looks great, thanks for working on this !

sys/arm/freescale/imx/imx_wdog.c

170 ↗

(On Diff #73120)

I guess this could be commited separatly.

sys/arm64/conf/GENERIC

116

How different are the IMX8 SoCs ?
Maybe we just need SOC_FREESCALE_IMX8 as I guess all the drivers are more or less the same and only a few clocks/device will be present or not.

sys/arm64/freescale/imx/clk/imx_clk_sscg_pll.c

152

This can be move above the divr1 = ... line I suppose.

sys/arm64/freescale/imx/imx7gpc.c

6

Do you want the "all rights reserved" mention ?

10

Where does that comes from ?

sys/arm64/freescale/imx/imx8mq_ccm.c

57

It's unfortunately GPLv2 licenced ...
What we did for rockchip is that we redefined those value.
I agree that this file cannot be licenced as it's just name/id representation but ...

62

Does the dummy clocks represent some unimplemented clocks or is it needed because the parent idx is 2 bits ?

sys/arm64/freescale/imx/imx_ccm_clk.h

6

Same comment as above for this mention.

sys/modules/dtb/imx8/Makefile

3

s/imx6/imx8/

[gonzo]

sys/arm64/conf/GENERIC

116

Yes, looks like the difference is mostly in set of blocks in the SoC, but overall they're conceptually the same: https://www.nxp.com/docs/en/supporting-information/IMX8LAYERCMPR.pdf

sys/arm64/freescale/imx/imx7gpc.c

10

I started by using arm/freescale/imx/imx_gpt.c but ended up completely rewriting it, so will remove it.

sys/arm64/freescale/imx/imx8mq_ccm.c

62

The latter I think. There is dummy clock id in the header file: IMX8MQ_CLK_DUMMY

[gonzo]

Address manu@ comments