in newer kernels 5.4.x, the device tree structure is quite different and the nodes lsio_pwm0-7 are completely missing.
Porting them from previous 4.14.x seems to be quite tricky.
Do you have any sample implementation working for iMX8QM?
I also need a solution for this. There's a bunch of imx8qm-ss-*.dtsi files but no imx8qm-ss-pwm.dtsi, so the PWMs are not usable, and directly reusing the PWM definitions from the 4.14 kernels isn't possible because the clock definitions have also changed.
Here's a link to the PWM nodes from kernel 4.14: fsl-imx8qm-device.dtsi\freescale\dts\boot\arm64\arch - linux-imx - i.MX Linux kernel
in kernel 4.14, pwm are available starting from here
The name was just pwmX, but were actually referring to LSIO area.
Please let me know if you need further details.