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boards/raspberrypi-4b: Bring up PWM devices

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Brings up PWM interfaces for the RPi4B when enabled.

Signed-off-by: Matteo Golin <matteo.golin@gmail.com>
This commit is contained in:
Matteo Golin 2026-07-08 16:17:27 -04:00 • committed by Xiang Xiao
parent 232d254275
commit 1971ddd081
6 changed files with 187 additions and 1 deletions
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9
boards/arm64/bcm2711/raspberrypi-4b/Kconfig
View file

@ -68,4 +68,13 @@ config RPI4B_BMP280
---help---
Registers the driver for the BMP280 sensor on I2C1 for experimenting.
config RPI4B_AUDIOJACK
bool "Enable audio over jack"
default n
depends on AUDIO_TONE
depends on BCM2711_PWM1
---help---
Enables PWM-based audio over the on-board audio jack. Device registered
as /dev/tone1.
endif # ARCH_BOARD_RASPBERRYPI_4B

6
boards/arm64/bcm2711/raspberrypi-4b/src/CMakeLists.txt
View file

@ -29,11 +29,15 @@ if(CONFIG_DEV_GPIO)
endif()
if(CONFIG_RPI4B_SDMMC)
list(APPEND rpi4b_sdmmc.c)
list(APPEND SRCS rpi4b_sdmmc.c)
endif()
if(CONFIG_BCM2711_I2C_DRIVER)
list(APPEND SRCS bcm2711_i2cdev.c)
endif()
if(CONFIG_BCM2711_PWM)
list(APPEND SRCS rpi4b_pwm.c)
endif()
target_sources(board PRIVATE ${SRCS})

4
boards/arm64/bcm2711/raspberrypi-4b/src/Makefile
View file

@ -38,6 +38,10 @@ ifeq ($(CONFIG_BCM2711_I2C_DRIVER),y)
CSRCS += bcm2711_i2cdev.c
endif
ifeq ($(CONFIG_BCM2711_PWM),y)
CSRCS += rpi4b_pwm.c
endif
include $(TOPDIR)/boards/Board.mk
.PHONY: distclean

13
boards/arm64/bcm2711/raspberrypi-4b/src/rpi4b.h
View file

@ -57,6 +57,19 @@ int rpi4b_bringup(void);
int rpi4b_sdmmc_initialize(void);
#endif
/****************************************************************************
* Name: rpi4b_pwm_initialize
*
* Description:
* Initialize PWM interfaces on the RPi4B.
* Also initializes PWM-audio driver if that was selected
*
****************************************************************************/
#if defined(CONFIG_BCM2711_PWM)
int rpi4b_pwm_initialize(void);
#endif
#if defined(CONFIG_DEV_GPIO)
int bcm2711_dev_gpio_init(void);
#endif /* defined(CONFIG_DEV_GPIO) */

4
boards/arm64/bcm2711/raspberrypi-4b/src/rpi4b_bringup.c
View file

@ -160,6 +160,10 @@ int rpi4b_bringup(void)
}
#endif
#ifdef CONFIG_BCM2711_PWM
ret = rpi4b_pwm_initialize();
#endif
#ifdef CONFIG_RPI4B_BMP280
struct i2c_master_s *i2c1 = bcm2711_i2cbus_initialize(1);
if (i2c1 == NULL)

152
boards/arm64/bcm2711/raspberrypi-4b/src/rpi4b_pwm.c Normal file
View file

@ -0,0 +1,152 @@
/****************************************************************************
* boards/arm64/bcm2711/raspberrypi-4b/src/rpi4b_pwm.c
*
* Contributed by: Matteo Golin <linguini@apache.org>
*
* SPDX-License-Identifer: Apache-2.0
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/debug.h>
#include <syslog.h>
#include <errno.h>
#include <nuttx/timers/pwm.h>
#include <nuttx/timers/oneshot.h>
#ifdef CONFIG_RPI4B_AUDIOJACK
#include <nuttx/audio/tone.h>
#endif
#include "bcm2711_pwm.h"
#include "bcm2711_oneshot.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: rpi4b_pwm_initialize
*
* Description:
* Initialize PWM interfaces on the RPi4B.
* Also initializes PWM-audio driver if that was selected
*
****************************************************************************/
int rpi4b_pwm_initialize(void)
{
int ret = 0;
int err = 0;
#ifdef CONFIG_BCM2711_PWM0
struct pwm_lowerhalf_s *pwm0;
#endif
#ifdef CONFIG_BCM2711_PWM1
struct pwm_lowerhalf_s *pwm1;
#endif
#ifdef CONFIG_RPI4B_AUDIOJACK
struct oneshot_lowerhalf_s *oneshot;
#endif
#ifdef CONFIG_BCM2711_PWM0
pwm0 = bcm2711_pwminitialize(0);
if (pwm0 == NULL)
{
syslog(LOG_ERR, "Couldn't initialize PWM0.");
err = -EAGAIN;
ret = err;
}
/* Only try to register if initialization was successful */
if (err == 0)
{
err = pwm_register("/dev/pwm0", pwm0);
if (err < 0)
{
syslog(LOG_ERR, "Couldn't register PWM0: %d\n", err);
ret = err;
}
}
#endif /* CONFIG_BCM2711_PWM0 */
#ifdef CONFIG_BCM2711_PWM1
pwm1 = bcm2711_pwminitialize(1);
if (pwm1 == NULL)
{
syslog(LOG_ERR, "Couldn't initialize PWM1.");
err = -EAGAIN;
ret = err;
}
/* Only try to register if initialization was successful */
if (err == 0)
{
err = pwm_register("/dev/pwm1", pwm1);
if (err < 0)
{
syslog(LOG_ERR, "Couldn't register PWM1: %d\n", err);
ret = err;
}
}
#endif /* CONFIG_BCM2711_PWM1 */
#ifdef CONFIG_RPI4B_AUDIOJACK
/* Don't try to register audio device with NULL lower-half */
if (pwm1 == NULL)
{
audwarn("PWM1 not setup, skipping tone registration.");
return ret;
}
/* Get a oneshot timer driver. We allocate timer 0 for this. I pick a
* random resolution of 10us since I know the BCM2711 timer driver can do
* 1us of resolution and ignores this parameter otherwise.
*/
oneshot = oneshot_initialize(0, 10);
if (oneshot == NULL)
{
syslog(LOG_ERR, "Couldn't initialize one-shot timer channel 0.");
return -EAGAIN;
}
/* NOTE: The PWM interface supports two channels. We register the audio
* device on the first one.
*/
audinfo("Registering /dev/tone1 using PWM1 channel 1.");
err = tone_register("/dev/tone1", pwm1, 1, oneshot);
if (err != 0)
{
syslog(LOG_ERR, "Couldn't register PWM audio tone driver: %d\n", err);
ret = err;
}
#endif /* CONFIG_RPI4B_AUDIOJACK */
return ret;
}