svn commit: r328259 - in head: share/man/man4 sys/arm/broadcom/bcm2835
Poul-Henning Kamp
phk at FreeBSD.org
Mon Jan 22 07:43:56 UTC 2018
Author: phk
Date: Mon Jan 22 07:43:54 2018
New Revision: 328259
URL: https://svnweb.freebsd.org/changeset/base/328259
Log:
Add skeleton manual page for bcm283x_pwm
(Feel free to improve this)
Added:
head/share/man/man4/bcm283x_pwm.4 (contents, props changed)
Modified:
head/share/man/man4/Makefile
head/sys/arm/broadcom/bcm2835/bcm2835_clkman.c
Modified: head/share/man/man4/Makefile
==============================================================================
--- head/share/man/man4/Makefile Mon Jan 22 07:15:24 2018 (r328258)
+++ head/share/man/man4/Makefile Mon Jan 22 07:43:54 2018 (r328259)
@@ -78,6 +78,7 @@ MAN= aac.4 \
axe.4 \
axge.4 \
bce.4 \
+ ${_bcm283x_pwm.4} \
bcma.4 \
bfe.4 \
bge.4 \
@@ -881,6 +882,10 @@ _vmm.4= vmm.4
.if ${MACHINE_CPUARCH} == "mips"
_nvram2env.4= nvram2env.4
+.endif
+
+.if ${MACHINE_ARCH:Marmv[67]*} != "" || ${MACHINE_CPUARCH} == "aarch64"
+_bcm283x_pwm.4= bcm283x_pwm.4
.endif
.if exists(${.CURDIR}/man4.${MACHINE_CPUARCH})
Added: head/share/man/man4/bcm283x_pwm.4
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/share/man/man4/bcm283x_pwm.4 Mon Jan 22 07:43:54 2018 (r328259)
@@ -0,0 +1,97 @@
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+.\"
+.\" Copyright (c) 2017 Poul-Henning Kamp <phk at FreeBSD.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\" notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\" notice, this list of conditions and the following disclaimer in the
+.\" documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd January 22, 2017
+.Dt BCM283X_PWM 4
+.Os
+.Sh NAME
+.Nm bcm283x_pwm
+.Nd bcm283x_pwm - driver for Raspberry Pi 2/3 PWM
+.Sh SYNOPSIS
+.Cd "kldload bcm283x_clkman"
+.Cd "kldload bcm283x_pwm"
+.Sh DESCRIPTION
+The
+.Nm
+driver provides access to the PWM engine on GPIO12 of Rpi 2 and 3 hardware.
+.Pp
+The PWM hardware is controlled via the
+.Xr sysctl 8
+interface:
+.Bd -literal
+dev.pwm.0.mode: 1
+dev.pwm.0.freq: 125000000
+dev.pwm.0.ratio: 2500
+dev.pwm.0.period: 10000
+dev.pwm.0.pwm_freq: 12500
+.Ed
+.Bl -tag -width ".Va dev.pwm.0.mode"
+.It Va dev.pwm.0.mode
+Three modes exist, 0=off, 1=PWM, 2=N/M.
+The N/M mode is a first order delta-sigma mode, which makes a quite
+handy DAC output with a trivial RC lowpass filter.
+.Pp
+.It Va dev.pwm.0.freq
+The input frequency to the PWM hardware in Hz.
+Minmum frequency is 123 kHz, maximum frequency is 125 MHz.
+.It Va dev.pwm.0.period
+The period length in cycles.
+In PWM mode, the output frequency will be
+(
+.Va dev.pwm.0.freq
+/
+.Va dev.pwm.0.period .
+)
+In N/M mode this is the 'M'
+.It Va dev.pwm.0.ratio
+The "on" period in cycles.
+In PWM mode, to get a 25% dutycycle, set this to 25% of
+.Va dev.pwm.0.period .
+In N/M mode this is the 'N'
+.It Va dev.pwm.0.pwm_freq
+The calculated PWM output frequency in PWM mode.
+.El
+.Pp
+.Sh NOTES
+Currently the
+.Nm
+driver ignores the 'status="disabled"' flag in the DTB, assuming that
+if you load the driver, you want it to work.
+.Sh SEE ALSO
+.Xr sysctl 8
+.Sh HISTORY
+The
+.Nm
+driver first appeared in
+.Fx 12.0 .
+.Sh AUTHORS
+.An -nosplit
+The
+.Nm
+driver and this manual page were written by
+.An Poul-Henning Kamp Aq Mt phk at FreeBSD.org .
Modified: head/sys/arm/broadcom/bcm2835/bcm2835_clkman.c
==============================================================================
--- head/sys/arm/broadcom/bcm2835/bcm2835_clkman.c Mon Jan 22 07:15:24 2018 (r328258)
+++ head/sys/arm/broadcom/bcm2835/bcm2835_clkman.c Mon Jan 22 07:43:54 2018 (r328259)
@@ -150,13 +150,13 @@ bcm2835_clkman_set_frequency(device_t dev, uint32_t un
u = 500000000/hz;
if (u < 4) {
device_printf(sc->sc_dev,
- "Frequency too high for unit 0x%x (max: 125MHz)",
+ "Frequency too high for unit 0x%x (max: 125 MHz)",
unit);
return (0);
}
if (u > 0xfff) {
device_printf(sc->sc_dev,
- "Frequency too low for unit 0x%x (min: 123Hz)",
+ "Frequency too low for unit 0x%x (min: 123 kHz)",
unit);
return (0);
}
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