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- /****************************************************************************
- * drivers/pwm/pwm.c
- *
- * Copyright (C) 2011-2013, 2016-2017 Gregory Nutt. All rights reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * 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.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "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
- * COPYRIGHT OWNER OR CONTRIBUTORS 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.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <sys/types.h>
- #include <stdint.h>
- #include <stdbool.h>
- #include <stdlib.h>
- #include <unistd.h>
- #include <string.h>
- #include <semaphore.h>
- #include <fcntl.h>
- #include <assert.h>
- #include <errno.h>
- #include <debug.h>
- #include <nuttx/arch.h>
- #include <nuttx/kmalloc.h>
- #include <nuttx/semaphore.h>
- #include <nuttx/fs/fs.h>
- #include <nuttx/drivers/pwm.h>
- #include <nuttx/irq.h>
- #ifdef CONFIG_PWM
- /****************************************************************************
- * Private Type Definitions
- ****************************************************************************/
- /* This structure describes the state of the upper half driver */
- struct pwm_upperhalf_s
- {
- uint8_t crefs; /* The number of times the device has been opened */
- volatile bool started; /* True: pulsed output is being generated */
- #ifdef CONFIG_PWM_PULSECOUNT
- volatile bool waiting; /* True: Caller is waiting for the pulse count to expire */
- #endif
- sem_t exclsem; /* Supports mutual exclusion */
- #ifdef CONFIG_PWM_PULSECOUNT
- sem_t waitsem; /* Used to wait for the pulse count to expire */
- #endif
- struct pwm_info_s info; /* Pulsed output characteristics */
- FAR struct pwm_lowerhalf_s *dev; /* lower-half state */
- };
- /****************************************************************************
- * Private Function Prototypes
- ****************************************************************************/
- static void pwm_dump(FAR const char *msg,
- FAR const struct pwm_info_s *info,
- bool started);
- static int pwm_open(FAR struct file *filep);
- static int pwm_close(FAR struct file *filep);
- static ssize_t pwm_read(FAR struct file *filep, FAR char *buffer,
- size_t buflen);
- static ssize_t pwm_write(FAR struct file *filep, FAR const char *buffer,
- size_t buflen);
- static int pwm_start(FAR struct pwm_upperhalf_s *upper,
- unsigned int oflags);
- static int pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg);
- /****************************************************************************
- * Private Data
- ****************************************************************************/
- static const struct file_operations g_pwmops =
- {
- pwm_open, /* open */
- pwm_close, /* close */
- pwm_read, /* read */
- pwm_write, /* write */
- 0, /* seek */
- pwm_ioctl /* ioctl */
- #ifndef CONFIG_DISABLE_POLL
- , 0 /* poll */
- #endif
- };
- /****************************************************************************
- * Private Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: pwm_dump
- ****************************************************************************/
- static void pwm_dump(FAR const char *msg, FAR const struct pwm_info_s *info,
- bool started)
- {
- #ifdef CONFIG_PWM_MULTICHAN
- int i;
- #endif
- pwminfo("%s: frequency: %d", msg, info->frequency);
- #ifdef CONFIG_PWM_MULTICHAN
- for (i = 0; i < CONFIG_PWM_NCHANNELS; i++)
- {
- pwminfo(" channel: %d duty: %08x",
- info->channels[i].channel, info->channels[i].duty);
- }
- #else
- pwminfo(" duty: %08x", info->duty);
- #endif
- #ifdef CONFIG_PWM_PULSECOUNT
- pwminfo(" count: %d\n", info->count);
- #endif
- pwminfo(" started: %d\n", started);
- }
- /****************************************************************************
- * Name: pwm_open
- *
- * Description:
- * This function is called whenever the PWM device is opened.
- *
- ****************************************************************************/
- static int pwm_open(FAR struct file *filep)
- {
- FAR struct inode *inode = filep->f_inode;
- FAR struct pwm_upperhalf_s *upper = inode->i_private;
- uint8_t tmp;
- int ret;
- pwminfo("crefs: %d\n", upper->crefs);
- /* Get exclusive access to the device structures */
- ret = nxsem_wait(&upper->exclsem);
- if (ret < 0)
- {
- goto errout;
- }
- /* Increment the count of references to the device. If this the first
- * time that the driver has been opened for this device, then initialize
- * the device.
- */
- tmp = upper->crefs + 1;
- if (tmp == 0)
- {
- /* More than 255 opens; uint8_t overflows to zero */
- ret = -EMFILE;
- goto errout_with_sem;
- }
- /* Check if this is the first time that the driver has been opened. */
- if (tmp == 1)
- {
- FAR struct pwm_lowerhalf_s *lower = upper->dev;
- /* Yes.. perform one time hardware initialization. */
- DEBUGASSERT(lower->ops->setup != NULL);
- pwminfo("calling setup\n");
- ret = lower->ops->setup(lower);
- if (ret < 0)
- {
- goto errout_with_sem;
- }
- }
- /* Save the new open count on success */
- upper->crefs = tmp;
- ret = OK;
- errout_with_sem:
- nxsem_post(&upper->exclsem);
- errout:
- return ret;
- }
- /****************************************************************************
- * Name: pwm_close
- *
- * Description:
- * This function is called when the PWM device is closed.
- *
- ****************************************************************************/
- static int pwm_close(FAR struct file *filep)
- {
- FAR struct inode *inode = filep->f_inode;
- FAR struct pwm_upperhalf_s *upper = inode->i_private;
- int ret;
- pwminfo("crefs: %d\n", upper->crefs);
- /* Get exclusive access to the device structures */
- ret = nxsem_wait(&upper->exclsem);
- if (ret < 0)
- {
- goto errout;
- }
- /* Decrement the references to the driver. If the reference count will
- * decrement to 0, then uninitialize the driver.
- */
- if (upper->crefs > 1)
- {
- upper->crefs--;
- }
- else
- {
- FAR struct pwm_lowerhalf_s *lower = upper->dev;
- /* There are no more references to the port */
- upper->crefs = 0;
- /* Disable the PWM device */
- DEBUGASSERT(lower->ops->shutdown != NULL);
- pwminfo("calling shutdown: %d\n");
- lower->ops->shutdown(lower);
- }
- ret = OK;
- nxsem_post(&upper->exclsem);
- errout:
- return ret;
- }
- /****************************************************************************
- * Name: pwm_read
- *
- * Description:
- * A dummy read method. This is provided only to satisfy the VFS layer.
- *
- ****************************************************************************/
- static ssize_t pwm_read(FAR struct file *filep, FAR char *buffer,
- size_t buflen)
- {
- /* Return zero -- usually meaning end-of-file */
- return 0;
- }
- /****************************************************************************
- * Name: pwm_write
- *
- * Description:
- * A dummy write method. This is provided only to satisfy the VFS layer.
- *
- ****************************************************************************/
- static ssize_t pwm_write(FAR struct file *filep, FAR const char *buffer,
- size_t buflen)
- {
- return 0;
- }
- /****************************************************************************
- * Name: pwm_start
- *
- * Description:
- * Handle the PWMIOC_START ioctl command
- *
- ****************************************************************************/
- #ifdef CONFIG_PWM_PULSECOUNT
- static int pwm_start(FAR struct pwm_upperhalf_s *upper, unsigned int oflags)
- {
- FAR struct pwm_lowerhalf_s *lower;
- irqstate_t flags;
- int ret = OK;
- DEBUGASSERT(upper != NULL);
- lower = upper->dev;
- DEBUGASSERT(lower != NULL && lower->ops->start != NULL);
- /* Verify that the PWM is not already running */
- if (!upper->started)
- {
- /* Disable interrupts to avoid race conditions */
- flags = enter_critical_section();
- /* Indicate that if will be waiting for the pulse count to complete.
- * Note that we will only wait if a non-zero pulse count is specified
- * and if the PWM driver was opened in normal, blocking mode. Also
- * assume for now that the pulse train will be successfully started.
- *
- * We do these things before starting the PWM to avoid race conditions.
- */
- upper->waiting = (upper->info.count > 0) && ((oflags & O_NONBLOCK) == 0);
- upper->started = true;
- /* Invoke the bottom half method to start the pulse train */
- ret = lower->ops->start(lower, &upper->info, upper);
- /* A return value of zero means that the pulse train was started
- * successfully.
- */
- if (ret == OK)
- {
- /* Should we wait for the pulse output to complete? Loop in
- * in case the wakeup form nxsem_wait() is a false alarm.
- */
- while (upper->waiting)
- {
- /* Wait until we are awakened by pwm_expired(). When
- * pwm_expired is called, it will post the waitsem and
- * clear the waiting flag.
- */
- int tmp = nxsem_wait(&upper->waitsem);
- DEBUGASSERT(tmp == OK || tmp == -EINTR);
- }
- }
- else
- {
- /* Looks like we won't be waiting after all */
- pwminfo("start failed: %d\n", ret);
- upper->started = false;
- upper->waiting = false;
- }
- leave_critical_section(flags);
- }
- return ret;
- }
- #else
- static int pwm_start(FAR struct pwm_upperhalf_s *upper, unsigned int oflags)
- {
- FAR struct pwm_lowerhalf_s *lower;
- int ret = OK;
- DEBUGASSERT(upper != NULL);
- lower = upper->dev;
- DEBUGASSERT(lower != NULL && lower->ops->start != NULL);
- /* Verify that the PWM is not already running */
- if (!upper->started)
- {
- /* Invoke the bottom half method to start the pulse train */
- ret = lower->ops->start(lower, &upper->info);
- /* A return value of zero means that the pulse train was started
- * successfully.
- */
- if (ret == OK)
- {
- /* Indicate that the pulse train has started */
- upper->started = true;
- }
- }
- return ret;
- }
- #endif
- /****************************************************************************
- * Name: pwm_ioctl
- *
- * Description:
- * The standard ioctl method. This is where ALL of the PWM work is done.
- *
- ****************************************************************************/
- static int pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
- {
- FAR struct inode *inode = filep->f_inode;
- FAR struct pwm_upperhalf_s *upper = inode->i_private;
- FAR struct pwm_lowerhalf_s *lower = upper->dev;
- int ret;
- pwminfo("cmd: %d arg: %ld\n", cmd, arg);
- /* Get exclusive access to the device structures */
- ret = nxsem_wait(&upper->exclsem);
- if (ret < 0)
- {
- return ret;
- }
- /* Handle built-in ioctl commands */
- switch (cmd)
- {
- /* PWMIOC_SETCHARACTERISTICS - Set the characteristics of the next pulsed
- * output. This command will neither start nor stop the pulsed output.
- * It will either setup the configuration that will be used when the
- * output is started; or it will change the characteristics of the pulsed
- * output on the fly if the timer is already started.
- *
- * ioctl argument: A read-only reference to struct pwm_info_s that provides
- * the characteristics of the pulsed output.
- */
- case PWMIOC_SETCHARACTERISTICS:
- {
- FAR const struct pwm_info_s *info = (FAR const struct pwm_info_s *)((uintptr_t)arg);
- DEBUGASSERT(info != NULL && lower->ops->start != NULL);
- pwm_dump("PWMIOC_SETCHARACTERISTICS", info, upper->started);
- /* Save the pulse train characteristics */
- memcpy(&upper->info, info, sizeof(struct pwm_info_s));
- /* If PWM is already running, then re-start it with the new characteristics */
- if (upper->started)
- {
- #ifdef CONFIG_PWM_PULSECOUNT
- ret = lower->ops->start(lower, &upper->info, upper);
- #else
- ret = lower->ops->start(lower, &upper->info);
- #endif
- }
- }
- break;
- /* PWMIOC_GETCHARACTERISTICS - Get the currently selected characteristics of
- * the pulsed output (independent of whether the output is start or stopped).
- *
- * ioctl argument: A reference to struct pwm_info_s to receive the
- * characteristics of the pulsed output.
- */
- case PWMIOC_GETCHARACTERISTICS:
- {
- FAR struct pwm_info_s *info = (FAR struct pwm_info_s *)((uintptr_t)arg);
- DEBUGASSERT(info != NULL);
- memcpy(info, &upper->info, sizeof(struct pwm_info_s));
- pwm_dump("PWMIOC_GETCHARACTERISTICS", info, upper->started);
- }
- break;
- /* PWMIOC_START - Start the pulsed output. The PWMIOC_SETCHARACTERISTICS
- * command must have previously been sent.
- *
- * ioctl argument: None
- */
- case PWMIOC_START:
- {
- pwm_dump("PWMIOC_START", &upper->info, upper->started);
- DEBUGASSERT(lower->ops->start != NULL);
- /* Start the pulse train */
- ret = pwm_start(upper, filep->f_oflags);
- }
- break;
- /* PWMIOC_STOP - Stop the pulsed output.
- *
- * ioctl argument: None
- */
- case PWMIOC_STOP:
- {
- pwminfo("PWMIOC_STOP: started: %d\n", upper->started);
- DEBUGASSERT(lower->ops->stop != NULL);
- if (upper->started)
- {
- ret = lower->ops->stop(lower);
- upper->started = false;
- #ifdef CONFIG_PWM_PULSECOUNT
- if (upper->waiting)
- {
- upper->waiting = false;
- }
- #endif
- }
- }
- break;
- /* Any unrecognized IOCTL commands might be platform-specific ioctl commands */
- default:
- {
- pwminfo("Forwarding unrecognized cmd: %d arg: %ld\n", cmd, arg);
- DEBUGASSERT(lower->ops->ioctl != NULL);
- ret = lower->ops->ioctl(lower, cmd, arg);
- }
- break;
- }
- nxsem_post(&upper->exclsem);
- return ret;
- }
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: pwm_register
- *
- * Description:
- * This function binds an instance of a "lower half" timer driver with the
- * "upper half" PWM device and registers that device so that can be used
- * by application code.
- *
- * When this function is called, the "lower half" driver should be in the
- * reset state (as if the shutdown() method had already been called).
- *
- * Input Parameters:
- * path - The full path to the driver to be registered in the NuttX pseudo-
- * filesystem. The recommended convention is to name all PWM drivers
- * as "/dev/pwm0", "/dev/pwm1", etc. where the driver path differs only
- * in the "minor" number at the end of the device name.
- * dev - A pointer to an instance of lower half timer driver. This instance
- * is bound to the PWM driver and must persists as long as the driver
- * persists.
- *
- * Returned Value:
- * Zero on success; a negated errno value on failure.
- *
- ****************************************************************************/
- int pwm_register(FAR const char *path, FAR struct pwm_lowerhalf_s *dev)
- {
- FAR struct pwm_upperhalf_s *upper;
- /* Allocate the upper-half data structure */
- upper = (FAR struct pwm_upperhalf_s *)kmm_zalloc(sizeof(struct pwm_upperhalf_s));
- if (!upper)
- {
- pwmerr("Allocation failed\n");
- return -ENOMEM;
- }
- /* Initialize the PWM device structure (it was already zeroed by kmm_zalloc()) */
- nxsem_init(&upper->exclsem, 0, 1);
- #ifdef CONFIG_PWM_PULSECOUNT
- nxsem_init(&upper->waitsem, 0, 0);
- /* The wait semaphore is used for signaling and, hence, should not have priority
- * inheritance enabled.
- */
- nxsem_setprotocol(&upper->waitsem, SEM_PRIO_NONE);
- #endif
- upper->dev = dev;
- /* Register the PWM device */
- pwminfo("Registering %s\n", path);
- return register_driver(path, &g_pwmops, 0666, upper);
- }
- /****************************************************************************
- * Name: pwm_expired
- *
- * Description:
- * If CONFIG_PWM_PULSECOUNT is defined and the pulse count was configured
- * to a non-zero value, then the "upper half" driver will wait for the
- * pulse count to expire. The sequence of expected events is as follows:
- *
- * 1. The upper half driver calls the start method, providing the lower
- * half driver with the pulse train characteristics. If a fixed
- * number of pulses is required, the 'count' value will be nonzero.
- * 2. The lower half driver's start() methoc must verify that it can
- * support the request pulse train (frequency, duty, AND pulse count).
- * If it cannot, it should return an error. If the pulse count is
- * non-zero, it should set up the hardware for that number of pulses
- * and return success. NOTE: That is CONFIG_PWM_PULSECOUNT is
- * defined, the start() method receives an additional parameter
- * that must be used in this callback.
- * 3. When the start() method returns success, the upper half driver
- * will "sleep" until the pwm_expired method is called.
- * 4. When the lower half detects that the pulse count has expired
- * (probably through an interrupt), it must call the pwm_expired
- * interface using the handle that was previously passed to the
- * start() method
- *
- * Input Parameters:
- * handle - This is the handle that was provided to the lower-half
- * start() method.
- *
- * Returned Value:
- * None
- *
- * Assumptions:
- * This function may be called from an interrupt handler.
- *
- ****************************************************************************/
- #ifdef CONFIG_PWM_PULSECOUNT
- void pwm_expired(FAR void *handle)
- {
- FAR struct pwm_upperhalf_s *upper = (FAR struct pwm_upperhalf_s *)handle;
- pwminfo("started: %d waiting: %d\n", upper->started, upper->waiting);
- /* Make sure that the PWM is started */
- if (upper->started)
- {
- /* Is there a thread waiting for the pulse train to complete? */
- if (upper->waiting)
- {
- /* Yes.. clear the waiting flag and awakened the waiting thread */
- upper->waiting = false;
- nxsem_post(&upper->waitsem);
- }
- /* The PWM is now stopped */
- upper->started = false;
- }
- }
- #endif
- #endif /* CONFIG_PWM */
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