Name
pwm_request_from_chip — 
     request a PWM device relative to a PWM chip
 
Arguments
- chip
- 
     PWM chip
     
- index
- 
     per-chip index of the PWM to request
     
- label
- 
     a literal description string of this PWM
     
Returns
   A pointer to the PWM device at the given index of the given PWM
   chip. A negative error code is returned if the index is not valid for the
   specified PWM chip or if the PWM device cannot be requested.