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.\" $FreeBSD$ 24.\" 25.Dd March 9, 2021 26.Dt PWMBUS 9 27.Os 28.Sh NAME 29.Nm pwmbus , 30.Nm PWMBUS_CHANNEL_CONFIG , 31.Nm PWMBUS_CHANNEL_COUNT , 32.Nm PWMBUS_CHANNEL_ENABLE , 33.Nm PWMBUS_CHANNEL_GET_CONFIG , 34.Nm PWMBUS_CHANNEL_GET_FLAGS , 35.Nm PWMBUS_CHANNEL_IS_ENABLED , 36.Nm PWMBUS_CHANNEL_SET_FLAGS , 37.Nm PWMBUS_GET_BUS 38.Nd PWMBUS methods 39.Sh SYNOPSIS 40.Cd "device pwm" 41.In "pwmbus_if.h" 42.Ft int 43.Fn PWMBUS_CHANNEL_CONFIG "device_t bus" "u_int channel" "u_int period" "u_int duty" 44.Ft int 45.Fn PWMBUS_CHANNEL_COUNT "device_t bus" "u_int *nchannel" 46.Ft int 47.Fn PWMBUS_CHANNEL_ENABLE "device_t bus" "u_int channel" "bool enable" 48.Ft int 49.Fn PWMBUS_CHANNEL_GET_CONFIG "device_t bus" "u_int channel" "u_int *period" "u_int *duty" 50.Ft int 51.Fn PWMBUS_CHANNEL_GET_FLAGS "device_t bus" "u_int channel" "uint32_t *flags" 52.Ft int 53.Fn PWMBUS_CHANNEL_IS_ENABLED "device_t bus" "u_int channel" "bool *enabled" 54.Ft int 55.Fn PWMBUS_CHANNEL_SET_FLAGS "device_t bus" "u_int channel" "uint32_t flags" 56.Sh DESCRIPTION 57The PWMBUS (Pulse-Width Modulation) interface allows a device driver to 58register to a global bus so other devices in the kernel can use them in a 59generic way. 60.Pp 61For all 62.Nm 63methods, the 64.Va period 65argument is the duration in nanoseconds of one complete on-off cycle, and the 66.Va duty 67argument is the duration in nanoseconds of the on portion of that cycle. 68.Pp 69Some PWM hardware is organized as a single controller with multiple channels. 70Channel numbers count up from zero. 71When multiple channels are present, they sometimes share a common clock or 72other resources. 73In such cases, changing the period or duty cycle of any one channel may affect 74other channels within the hardware which share the same resources. 75Consult the documentation for the underlying PWM hardware device driver for 76details on channels that share resources. 77.Sh INTERFACE 78.Bl -tag -width indent 79.It Fn PWMBUS_CHANNEL_CONFIG "device_t bus" "u_int channel" "u_int period" "u_int duty" 80Configure the period and duty (in nanoseconds) in the PWM controller on the bus 81for the specified channel. 82Returns 0 on success or 83.Er EINVAL 84if the values are not supported by the controller or 85.Er EBUSY 86if the PWMBUS controller is in use and does not support changing the value on 87the fly. 88.It Fn PWMBUS_CHANNEL_COUNT "device_t bus" "u_int *nchannel" 89Get the number of channels supported by the controller. 90.It Fn PWMBUS_CHANNEL_ENABLE "device_t bus" "u_int channel" "bool enable" 91Enable the PWM channel. 92.It Fn PWMBUS_CHANNEL_GET_CONFIG "device_t bus" "u_int channel" "u_int *period" "u_int *duty" 93Get the current configuration of the period and duty for the specified channel. 94.It Fn PWMBUS_CHANNEL_GET_FLAGS "device_t bus" "u_int channel" "uint32_t *flags" 95Get the current flags for the channel. 96If the driver or controller 97does not support this, a default method returns a flags value of zero. 98.It Fn PWMBUS_CHANNEL_IS_ENABLED "device_t bus" "u_int channel" "bool *enable" 99Test whether the PWM channel is enabled. 100.It Fn PWMBUS_CHANNEL_SET_FLAGS "device_t bus" "u_int channel" "uint32_t flags" 101Set the flags of the channel (such as inverted polarity). 102If the driver or controller does not support this a do-nothing default method 103is used. 104.El 105.Sh HISTORY 106The 107.Nm pwmbus 108interface first appear in 109.Fx 13.0 . 110The 111.Nm pwmbus 112interface and manual page was written by 113.An Emmanuel Vadot Aq Mt manu@FreeBSD.org . 114