1.\" Copyright (c) 2018 Emmanuel Vadot <manu@freebsd.org> 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright 9.\" notice, this list of conditions and the following disclaimer in the 10.\" documentation and/or other materials provided with the distribution. 11.\" 12.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 13.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 14.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 15.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 16.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 17.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 18.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 19.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 20.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 21.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 22.\" 23.Dd March 9, 2021 24.Dt PWMBUS 9 25.Os 26.Sh NAME 27.Nm pwmbus , 28.Nm PWMBUS_CHANNEL_CONFIG , 29.Nm PWMBUS_CHANNEL_COUNT , 30.Nm PWMBUS_CHANNEL_ENABLE , 31.Nm PWMBUS_CHANNEL_GET_CONFIG , 32.Nm PWMBUS_CHANNEL_GET_FLAGS , 33.Nm PWMBUS_CHANNEL_IS_ENABLED , 34.Nm PWMBUS_CHANNEL_SET_FLAGS , 35.Nm PWMBUS_GET_BUS 36.Nd PWMBUS methods 37.Sh SYNOPSIS 38.Cd "device pwm" 39.In "pwmbus_if.h" 40.Ft int 41.Fn PWMBUS_CHANNEL_CONFIG "device_t bus" "u_int channel" "u_int period" "u_int duty" 42.Ft int 43.Fn PWMBUS_CHANNEL_COUNT "device_t bus" "u_int *nchannel" 44.Ft int 45.Fn PWMBUS_CHANNEL_ENABLE "device_t bus" "u_int channel" "bool enable" 46.Ft int 47.Fn PWMBUS_CHANNEL_GET_CONFIG "device_t bus" "u_int channel" "u_int *period" "u_int *duty" 48.Ft int 49.Fn PWMBUS_CHANNEL_GET_FLAGS "device_t bus" "u_int channel" "uint32_t *flags" 50.Ft int 51.Fn PWMBUS_CHANNEL_IS_ENABLED "device_t bus" "u_int channel" "bool *enabled" 52.Ft int 53.Fn PWMBUS_CHANNEL_SET_FLAGS "device_t bus" "u_int channel" "uint32_t flags" 54.Sh DESCRIPTION 55The PWMBUS (Pulse-Width Modulation) interface allows a device driver to 56register to a global bus so other devices in the kernel can use them in a 57generic way. 58.Pp 59For all 60.Nm 61methods, the 62.Va period 63argument is the duration in nanoseconds of one complete on-off cycle, and the 64.Va duty 65argument is the duration in nanoseconds of the on portion of that cycle. 66.Pp 67Some PWM hardware is organized as a single controller with multiple channels. 68Channel numbers count up from zero. 69When multiple channels are present, they sometimes share a common clock or 70other resources. 71In such cases, changing the period or duty cycle of any one channel may affect 72other channels within the hardware which share the same resources. 73Consult the documentation for the underlying PWM hardware device driver for 74details on channels that share resources. 75.Sh INTERFACE 76.Bl -tag -width indent 77.It Fn PWMBUS_CHANNEL_CONFIG "device_t bus" "u_int channel" "u_int period" "u_int duty" 78Configure the period and duty (in nanoseconds) in the PWM controller on the bus 79for the specified channel. 80Returns 0 on success or 81.Er EINVAL 82if the values are not supported by the controller or 83.Er EBUSY 84if the PWMBUS controller is in use and does not support changing the value on 85the fly. 86.It Fn PWMBUS_CHANNEL_COUNT "device_t bus" "u_int *nchannel" 87Get the number of channels supported by the controller. 88.It Fn PWMBUS_CHANNEL_ENABLE "device_t bus" "u_int channel" "bool enable" 89Enable the PWM channel. 90.It Fn PWMBUS_CHANNEL_GET_CONFIG "device_t bus" "u_int channel" "u_int *period" "u_int *duty" 91Get the current configuration of the period and duty for the specified channel. 92.It Fn PWMBUS_CHANNEL_GET_FLAGS "device_t bus" "u_int channel" "uint32_t *flags" 93Get the current flags for the channel. 94If the driver or controller 95does not support this, a default method returns a flags value of zero. 96.It Fn PWMBUS_CHANNEL_IS_ENABLED "device_t bus" "u_int channel" "bool *enable" 97Test whether the PWM channel is enabled. 98.It Fn PWMBUS_CHANNEL_SET_FLAGS "device_t bus" "u_int channel" "uint32_t flags" 99Set the flags of the channel (such as inverted polarity). 100If the driver or controller does not support this a do-nothing default method 101is used. 102.El 103.Sh HISTORY 104The 105.Nm pwmbus 106interface first appear in 107.Fx 13.0 . 108The 109.Nm pwmbus 110interface and manual page was written by 111.An Emmanuel Vadot Aq Mt manu@FreeBSD.org . 112