In iMX6 datasheet chapter 51 PWM
Digital sample values can be loaded into the pulse-width modulator as 16-bit words. The
endianess can be changed using the BCTR and HCTR bits of the control register. A 4-
word (16-bit) FIFO minimizes interrupt overhead. A maskable interrupt is generated
when the number of data words fall below the water level set by the FWM field in the
Give please an example how to request this interrupt in linux 3.10.53.