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litex: Add PWM driver.

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PWM driver for multiple peripherals supplied in gateware.

Only single channel frequency and duty cycle control is implemented. Pulse counting and multichannel features are not currently feasible.

Additions also include a new board configuration for arty-a7 which enables the PWM driver and example application.
This commit is contained in:
Stuart Ianna 2023-02-01 14:35:51 +11:00 committed by Alan Carvalho de Assis
parent 52eaefcc8e
commit 05c6d7c7b9
10 changed files with 628 additions and 0 deletions
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4
arch/risc-v/src/litex/Kconfig
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@ -102,6 +102,10 @@ config LITEX_SDIO1
select LITEX_SDIO_DMA
depends on LITEX_SDIO
config LITEX_PWM
bool "Enable PWM controller"
default n
if LITEX_SDIO1
config LITEX_IDMODE_FREQ

4
arch/risc-v/src/litex/Make.defs
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@ -43,3 +43,7 @@ endif
ifeq ($(CONFIG_LITEX_ETHMAC),y)
CHIP_CSRCS += litex_emac.c
endif
ifeq ($(CONFIG_LITEX_PWM),y)
CHIP_CSRCS += litex_pwm.c
endif

15
arch/risc-v/src/litex/hardware/litex_memorymap.h
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@ -64,6 +64,21 @@
#define LITEX_GPIO_OFFSET 0x00000020
#define LITEX_GPIO_MAX 8
/* PWM peripheral definitions.
* - LITEX_PWM_BASE is the first 32-bit address which contains a block
* of PWM registers (peripheral). Each block controls a single output
* channel.
* - LITEX_PWM_OFFSET is the number of bytes between each PWM peripheral.
* - LITEX_PWM_MAX is the number of peripherals enabled in gateware.
*
* Each peripheral is referenced by an index in the PWM driver. E.g Index 0
* is the first PWM peripheral at 0xF0009800. Index 1 is at 0xF0009008C.
*/
#define LITEX_PWM_BASE 0xf0009800
#define LITEX_PWM_OFFSET 0x0000000c
#define LITEX_PWM_MAX 4
#define LITEX_ETHMAC_RXBASE 0x80000000
#define LITEX_ETHMAC_TXBASE 0x80001000

357
arch/risc-v/src/litex/litex_pwm.c Normal file
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@ -0,0 +1,357 @@
/****************************************************************************
* arch/risc-v/src/litex/litex_pwm.c
*
* 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 <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <arch/board/board.h>
#include "riscv_internal.h"
#include "litex_pwm.h"
#include "litex_clockconfig.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#ifdef CONFIG_PWM_PULSECOUNT
#error PWM puslecount not supported for Litex.
#endif
#ifdef CONFIG_PWM_MULTICHAN
#error PWM multichannel not supported for Litex.
#endif
/* Control register offsets from peripheral base address */
#define PWM_ENABLE_REG_OFFSET 0 /* Enable register */
#define PWM_WIDTH_REG_OFFSET 4 /* Pulse width control register */
#define PWM_PERIOD_REG_OFFSET 8 /* Period register*/
/* Enable register bit definitions */
#define PWM_ENABLE_SET_BIT 1 /* Bit used to enable/disable PWM */
/* The minimum period required for *sane* operation. This ensures that
* setting the duty cycle actually makes sense. However, it does limit
* the maximum PWM frequency.
*/
#define PWM_MINIMUM_PERIOD 10
/****************************************************************************
* Private Types
****************************************************************************/
struct litex_pwm_s
{
const struct pwm_ops_s *ops; /* PWM operations */
uint32_t base; /* Base address of PWM register */
uint32_t frequency; /* The current frequency */
uint32_t duty; /* The current duty cycle */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* PWM driver methods needed by lower half driver operations */
static int litex_pwm_setup(struct pwm_lowerhalf_s *dev);
static int litex_pwm_shutdown(struct pwm_lowerhalf_s *dev);
static int litex_pwm_start(struct pwm_lowerhalf_s *dev,
const struct pwm_info_s *info);
static int litex_pwm_stop(struct pwm_lowerhalf_s *dev);
static int litex_pwm_ioctl(struct pwm_lowerhalf_s *dev,
int cmd, unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
/* This is the list of lower half PWM driver methods used by the upper half
* driver.
*/
static const struct pwm_ops_s g_litex_pwmops =
{
.setup = litex_pwm_setup,
.shutdown = litex_pwm_shutdown,
.start = litex_pwm_start,
.stop = litex_pwm_stop,
.ioctl = litex_pwm_ioctl,
};
/* Data structure containing the operations and base address for all enabled
* peripherals.
*/
struct litex_pwm_s g_litex_pwm_inst[] =
{ [0 ... LITEX_PWM_MAX]
{
.ops = &g_litex_pwmops,
.base = 0,
.frequency = 0,
.duty = 0
}
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: litex_pwm_setup
*
* Description:
* This method is called when the driver is opened. The lower half driver
* should configure and initialize the device so that it is ready for use.
* It should not, however, output pulses until the start method is called.
*
* Input Parameters:
* dev - A pointer to the lower half instance to operate on.
*
* Returned Value:
* OK on success. A negated error number is returned on failure.
*
****************************************************************************/
static int litex_pwm_setup(struct pwm_lowerhalf_s *dev)
{
struct litex_pwm_s *priv = (struct litex_pwm_s *)dev;
int ret = OK;
DEBUGASSERT(dev);
DEBUGASSERT(priv->base);
/* Just make sure that the device is not going to output anything */
putreg32(0, priv->base + PWM_ENABLE_REG_OFFSET);
return ret;
}
/****************************************************************************
* Name: litex_pwm_shutdown
*
* Description:
* This method is called when the driver is closed. The lower half driver
* stop pulsed output, free any resources, disable the timer hardware, and
* put the system into the lowest possible power usage state
*
* Input Parameters:
* dev - A pointer to the lower half instance to operate on.
*
* Returned Value:
* OK on success. A negated error number is returned on failure.
*
****************************************************************************/
static int litex_pwm_shutdown(struct pwm_lowerhalf_s *dev)
{
struct litex_pwm_s *priv = (struct litex_pwm_s *)dev;
int ret = OK;
DEBUGASSERT(dev);
DEBUGASSERT(priv->base);
/* Disable PWM output */
putreg32(0, priv->base + PWM_ENABLE_REG_OFFSET);
return ret;
}
/****************************************************************************
* Name: litex_pwm_start
*
* Description:
* (Re-)initialize the PWM and start the pulsed output
*
* Input Parameters:
* dev - A pointer to the lower half instance to operate on.
* info - Structure containing the desired PWM characteristics.
*
* Returned Value:
* OK on success. A negated error number is returned on failure.
*
****************************************************************************/
static int litex_pwm_start(struct pwm_lowerhalf_s *dev,
const struct pwm_info_s *info)
{
struct litex_pwm_s *priv = (struct litex_pwm_s *)dev;
int ret = OK;
uint32_t sysclk_freq;
uint32_t period;
uint32_t duty;
bool update_frequency;
bool update_duty;
const uint32_t max_in_duty = 65536;
const uint32_t min_in_duty = 1;
update_frequency = priv->frequency != info->frequency;
update_duty = update_frequency | (priv->duty != info->duty);
DEBUGASSERT(dev);
DEBUGASSERT(priv->base);
if (update_frequency)
{
if (info->frequency == 0)
{
pwmwarn("Cannot set PMW to a frequency of 0Hz\n");
return -EPERM;
}
/* Calculate the period for the required frequency */
sysclk_freq = litex_get_hfclk();
period = sysclk_freq / info->frequency;
if (period < PWM_MINIMUM_PERIOD)
{
pwmwarn("Frequency %luHz too high for sysclk %luHz\n",
info->frequency, sysclk_freq);
return -EPERM;
}
priv->frequency = info->frequency;
putreg32(period, priv->base + PWM_PERIOD_REG_OFFSET);
pwminfo("Update PWM period to %lu\n", period);
}
if (update_duty)
{
/* Map the duty cycle compare to the period */
/* The period may have already been calculated when adjusting the
* frequency. However, if the frequency doesn't change, it will be
* set to an undefined value. Just fetch it each time from hardware.
*/
period = getreg32(priv->base + PWM_PERIOD_REG_OFFSET);
duty = period * (info->duty / (float)(max_in_duty - min_in_duty));
priv->duty = info->duty;
putreg32(duty, priv->base + PWM_WIDTH_REG_OFFSET);
pwminfo("Update PWM duty to %lu\n", duty);
}
putreg32(PWM_ENABLE_SET_BIT, priv->base + PWM_ENABLE_REG_OFFSET);
return ret;
}
/****************************************************************************
* Name: litex_pwm_stop
*
* Description:
* Stop the PWM
*
* Input Parameters:
* dev - A pointer to the lower half instance to operate on.
*
* Returned Value:
* OK on success. A negated error number is returned on failure.
*
****************************************************************************/
static int litex_pwm_stop(struct pwm_lowerhalf_s *dev)
{
struct litex_pwm_s *priv = (struct litex_pwm_s *)dev;
DEBUGASSERT(dev);
DEBUGASSERT(priv->base);
putreg32(0, priv->base + PWM_ENABLE_REG_OFFSET);
return OK;
}
/****************************************************************************
* Name: litex_pwm_ioctl
*
* Description:
* Lower-half logic may support platform-specific ioctl commands.
* Not implemented for Litex.
*
* Input Parameters:
* dev - A pointer to the lower half instance to operate on.
* cmd - IO control command.
* arg - IO control command argument.
*
* Returned Value:
* OK on success. A negated error number is returned on failure.
*
****************************************************************************/
static int litex_pwm_ioctl(struct pwm_lowerhalf_s *dev,
int cmd, unsigned long arg)
{
/* There are no platform-specific ioctl commands */
UNUSED(dev);
UNUSED(cmd);
UNUSED(arg);
return -ENOTTY;
}
/****************************************************************************
* Public Function
****************************************************************************/
/****************************************************************************
* Name: litex_pwminitialize
*
* Description:
* Initialize one PWM channel
*
* Input Parameters:
* pwm - A number identifying the pwm instance.
*
* Returned Value:
* On success, a pointer to the Litex lower half PWM driver is returned.
* NULL is returned on any failure.
*
****************************************************************************/
struct pwm_lowerhalf_s *litex_pwminitialize(int pwm)
{
struct litex_pwm_s *lower = NULL;
if (pwm >= LITEX_PWM_MAX)
{
return NULL;
}
lower = &g_litex_pwm_inst[pwm];
lower->base = LITEX_PWM_BASE + (LITEX_PWM_OFFSET * pwm);
return (struct pwm_lowerhalf_s *)lower;
}

57
arch/risc-v/src/litex/litex_pwm.h Normal file
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@ -0,0 +1,57 @@
/****************************************************************************
* arch/risc-v/src/litex/litex_pwm.h
*
* 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.
*
****************************************************************************/
#ifndef __ARCH_RISCV_LITEX_LITEX_PWM_H
#define __ARCH_RISCV_LITEX_LITEX_PWM_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/timers/pwm.h>
#include "hardware/litex_memorymap.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
/****************************************************************************
* Name: litex_pwminitialize
*
* Description:
* Initialize one timer for use with the upper_level PWM driver.
*
* Input Parameters:
* pwm - A number identifying the pwm instance.
*
* Returned Value:
* On success, a pointer to the Litex lower half PWM driver is returned.
* NULL is returned on any failure.
*
****************************************************************************/
struct pwm_lowerhalf_s *litex_pwminitialize(int pwm);
#endif /* __ARCH_RISCV_LITEX_LITEX_PWM_H */

72
boards/risc-v/litex/arty_a7/configs/pwm/defconfig Normal file
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@ -0,0 +1,72 @@
#
# This file is autogenerated: PLEASE DO NOT EDIT IT.
#
# You can use "make menuconfig" to make any modifications to the installed .config file.
# You can then do "make savedefconfig" to generate a new defconfig file that includes your
# modifications.
#
# CONFIG_DISABLE_PTHREAD is not set
# CONFIG_FS_PROCFS_EXCLUDE_BLOCKS is not set
# CONFIG_FS_PROCFS_EXCLUDE_ENVIRON is not set
# CONFIG_FS_PROCFS_EXCLUDE_MEMDUMP is not set
# CONFIG_FS_PROCFS_EXCLUDE_MEMINFO is not set
# CONFIG_FS_PROCFS_EXCLUDE_MOUNT is not set
# CONFIG_FS_PROCFS_EXCLUDE_MOUNTS is not set
# CONFIG_FS_PROCFS_EXCLUDE_PROCESS is not set
# CONFIG_FS_PROCFS_EXCLUDE_UPTIME is not set
# CONFIG_FS_PROCFS_EXCLUDE_USAGE is not set
# CONFIG_FS_PROCFS_EXCLUDE_VERSION is not set
# CONFIG_NSH_DISABLEBG is not set
# CONFIG_NSH_DISABLE_LOSMART is not set
# CONFIG_NSH_DISABLE_UNAME is not set
# CONFIG_STANDARD_SERIAL is not set
CONFIG_ARCH="risc-v"
CONFIG_ARCH_BOARD="arty_a7"
CONFIG_ARCH_BOARD_ARTY_A7=y
CONFIG_ARCH_CHIP="litex"
CONFIG_ARCH_CHIP_LITEX=y
CONFIG_ARCH_INTERRUPTSTACK=8192
CONFIG_ARCH_RISCV=y
CONFIG_ARCH_STACKDUMP=y
CONFIG_BINFMT_DISABLE=y
CONFIG_BOARD_LOOPSPERMSEC=10000
CONFIG_BUILTIN=y
CONFIG_DEBUG_FULLOPT=y
CONFIG_DEBUG_SYMBOLS=y
CONFIG_DEFAULT_SMALL=y
CONFIG_DEV_ZERO=y
CONFIG_EXAMPLES_HELLO=y
CONFIG_EXAMPLES_HELLO_STACKSIZE=8192
CONFIG_EXAMPLES_PWM=y
CONFIG_FS_PROCFS=y
CONFIG_IDLETHREAD_STACKSIZE=8192
CONFIG_INIT_ENTRYPOINT="nsh_main"
CONFIG_INIT_STACKSIZE=8192
CONFIG_INTELHEX_BINARY=y
CONFIG_LIBC_PERROR_STDOUT=y
CONFIG_LIBC_STRERROR=y
CONFIG_LITEX_PWM=y
CONFIG_NFILE_DESCRIPTORS_PER_BLOCK=6
CONFIG_NSH_ARCHINIT=y
CONFIG_NSH_BUILTIN_APPS=y
CONFIG_NSH_FILEIOSIZE=64
CONFIG_NSH_STRERROR=y
CONFIG_POSIX_SPAWN_DEFAULT_STACKSIZE=8192
CONFIG_PTHREAD_STACK_DEFAULT=8192
CONFIG_PWM=y
CONFIG_RAM_SIZE=268435456
CONFIG_RAM_START=0x40000000
CONFIG_RAW_BINARY=y
CONFIG_RR_INTERVAL=200
CONFIG_SCHED_WAITPID=y
CONFIG_STACK_COLORATION=y
CONFIG_START_DAY=20
CONFIG_START_MONTH=3
CONFIG_START_YEAR=2020
CONFIG_STDIO_DISABLE_BUFFERING=y
CONFIG_SYSTEM_NSH=y
CONFIG_TASK_NAME_SIZE=12
CONFIG_TESTING_GETPRIME=y
CONFIG_UART0_RXBUFSIZE=128
CONFIG_UART0_SERIAL_CONSOLE=y
CONFIG_UART0_TXBUFSIZE=128

4
boards/risc-v/litex/arty_a7/src/Makefile
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@ -34,4 +34,8 @@ ifeq ($(CONFIG_FS_AUTOMOUNTER),y)
CSRCS += litex_automount.c
endif
ifeq ($(CONFIG_LITEX_PWM),y)
CSRCS += litex_pwm.c
endif
include $(TOPDIR)/boards/Board.mk

17
boards/risc-v/litex/arty_a7/src/arty_a7.h
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@ -144,4 +144,21 @@ void litex_automount_event(int slotno, bool inserted);
bool litex_cardinserted(int slotno);
#endif
/****************************************************************************
* Name: litex_pwm_setup
*
* Description:
* Initialise all PWM channels enabled in gateware and map them to
* /dev/pwmX. Where X is the PMW channel number. From 0 ... LITEX_PWM_MAX.
*
* Returned Value:
* OK is returned on success.
* -ENODEV is return on the first PWM device initialise failure.
*
****************************************************************************/
#ifdef CONFIG_LITEX_PWM
int litex_pwm_setup(void);
#endif
#endif /* __BOARDS_RISCV_LITEX_ARTY_A7_SRC_ARTY_A7_H */

9
boards/risc-v/litex/arty_a7/src/litex_bringup.c
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@ -102,5 +102,14 @@ int litex_bringup(void)
#endif /* CONFIG_LITEX_SDIO */
#ifdef CONFIG_LITEX_PWM
ret = litex_pwm_setup();
if (ret != OK)
{
syslog(LOG_ERR, "ERROR: Failed to setup PWM driver \n");
}
#endif /* CONFIG_LITEX_PWM */
return ret;
}

89
boards/risc-v/litex/arty_a7/src/litex_pwm.c Normal file
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@ -0,0 +1,89 @@
/****************************************************************************
* boards/risc-v/litex/arty_a7/src/litex_pwm.c
*
* 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 <errno.h>
#include <debug.h>
#include <stddef.h>
#include <stdio.h>
#include <nuttx/timers/pwm.h>
#include <arch/board/board.h>
#include "litex_pwm.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: litex_pwm_setup
*
* Description:
* Initialise all PWM channels enabled in gateware and map them to
* /dev/pwmX. Where X is the PMW channel number. From 0 ... LITEX_PWM_MAX.
*
* Returned Value:
* OK is returned on success.
* -ENODEV is return on the first PWM device initialise failure.
*
****************************************************************************/
int litex_pwm_setup(void)
{
struct pwm_lowerhalf_s *pwm = NULL;
int ret = OK;
int channel;
char devpath[12] =
{
0
};
for (channel = 0; channel < LITEX_PWM_MAX; channel++)
{
pwm = litex_pwminitialize(channel);
if (!pwm)
{
pwmerr("Failed fetching PWM channel %d lower half\n", channel);
return -ENODEV;
}
/* Register the PWM driver at "/dev/pwmX" */
snprintf(devpath, 12, "/dev/pwm%d", channel);
ret = pwm_register(devpath, pwm);
if (ret < 0)
{
pwmerr("pwm_register channel %d failed: %d\n", channel, ret);
return ret;
}
}
return ret;
}