Hi libsong,
When you have enabled Pin 32 as PWM, you must see bit 0 of register 0x700031fc to be set.
You can use busybox devmem tool to read any register.
Then run following sysfs nodes:
echo 0 > /sys/class/pwm/pwmchip0/export
echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable
This will enable the PWM controller. PWM controller register address is 0x7000a000 so after enabling it, you can see Bit 31 to be set.
Please try above and let me know if PWM is still not working.
Thanks,
Shubhi