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PWMBUS(9)		    Kernel Developer's Manual		       PWMBUS(9)

NAME
     pwmbus, PWMBUS_CHANNEL_CONFIG, PWMBUS_CHANNEL_COUNT, PWMBUS_CHANNEL_ENABLE,
     PWMBUS_CHANNEL_GET_CONFIG, 		       PWMBUS_CHANNEL_GET_FLAGS,
     PWMBUS_CHANNEL_IS_ENABLED, PWMBUS_CHANNEL_SET_FLAGS, PWMBUS_GET_BUS -- PWM-
     BUS methods

SYNOPSIS
     device pwm
     #include <pwmbus_if.h>

     int
     PWMBUS_CHANNEL_CONFIG(device_t bus, u_int channel, u_int period,
	   u_int duty);

     int
     PWMBUS_CHANNEL_COUNT(device_t bus, u_int *nchannel);

     int
     PWMBUS_CHANNEL_ENABLE(device_t bus, u_int channel, bool enable);

     int
     PWMBUS_CHANNEL_GET_CONFIG(device_t bus, u_int channel, u_int *period,
	   u_int *duty);

     int
     PWMBUS_CHANNEL_GET_FLAGS(device_t bus, u_int channel, uint32_t *flags);

     int
     PWMBUS_CHANNEL_IS_ENABLED(device_t bus, u_int channel, bool *enabled);

     int
     PWMBUS_CHANNEL_SET_FLAGS(device_t bus, u_int channel, uint32_t flags);

DESCRIPTION
     The PWMBUS (Pulse-Width Modulation) interface allows  a  device  driver  to
     register  to  a global bus so other devices in the kernel can use them in a
     generic way.

     For all pwmbus methods, the period argument is the duration in  nanoseconds
     of  one  complete	on-off	cycle,	and the duty argument is the duration in
     nanoseconds of the on portion of that cycle.

     Some PWM hardware is organized as a single controller with  multiple  chan-
     nels.   Channel  numbers  count  up  from zero.  When multiple channels are
     present, they sometimes share a common clock or other resources.	In  such
     cases,  changing  the  period  or	duty cycle of any one channel may affect
     other channels within the hardware which share the same resources.  Consult
     the documentation for the underlying PWM hardware device driver for details
     on channels that share resources.

INTERFACE
     PWMBUS_CHANNEL_CONFIG(device_t bus,  u_int  channel,  u_int  period,  u_int
	     duty)
	     Configure	the  period  and  duty	(in nanoseconds) in the PWM con-
	     troller on the bus for the specified channel.  Returns 0 on success
	     or EINVAL if the values are not  supported  by  the  controller  or
	     EBUSY  if	the  PWMBUS  controller  is  in use and does not support
	     changing the value on the fly.

     PWMBUS_CHANNEL_COUNT(device_t bus, u_int *nchannel)
	     Get the number of channels supported by the controller.

     PWMBUS_CHANNEL_ENABLE(device_t bus, u_int channel, bool enable)
	     Enable the PWM channel.

     PWMBUS_CHANNEL_GET_CONFIG(device_t bus, u_int channel, u_int *period, u_int
	     *duty)
	     Get the current configuration of the period and duty for the speci-
	     fied channel.

     PWMBUS_CHANNEL_GET_FLAGS(device_t bus, u_int channel, uint32_t *flags)
	     Get the current flags for the channel.  If the driver or controller
	     does not support this, a default method returns a	flags  value  of
	     zero.

     PWMBUS_CHANNEL_IS_ENABLED(device_t bus, u_int channel, bool *enable)
	     Test whether the PWM channel is enabled.

     PWMBUS_CHANNEL_SET_FLAGS(device_t bus, u_int channel, uint32_t flags)
	     Set  the  flags of the channel (such as inverted polarity).  If the
	     driver or controller does not support  this  a  do-nothing  default
	     method is used.

HISTORY
     The  pwmbus  interface  first appear in FreeBSD 13.0.  The pwmbus interface
     and manual page was written by Emmanuel Vadot <manu@FreeBSD.org>.

FreeBSD ports 15.1		  March 9, 2021 		       PWMBUS(9)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=pwm&sektion=9&manpath=FreeBSD+15.1-RELEASE+and+Ports>

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