Each MCPWM operator has two Trigger (named T0 and T1), and they can be
routed to GPIO fault signal or timer sync event.Generator can be set up
to perform different action on Trigger event.
This commit add a trigger driver and a test for the driver.
MCPWM group clock pre scale was originally fixed to 2, which is
inconvenient. Set group clock prescale dynamically. Now the maximum
resolution of the MCPWM timer is up to 160MHz(when the prescale set
to 1). And add a resulotion config for MCPWM capture.
The MCPWM carrier is part of the operator and can work independently
without the MCPWM timer being enabled. This commit add the MCPWM
carrier clk source.
