/**************************************************************************** * drivers/timers/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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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 mutex_t lock; /* 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 */ NULL, /* seek */ pwm_ioctl, /* ioctl */ NULL /* poll */ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS , NULL /* unlink */ #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: %" PRId32 "\n", msg, info->frequency); #ifdef CONFIG_PWM_MULTICHAN for (i = 0; i < CONFIG_PWM_NCHANNELS; i++) { pwminfo(" channel: %d duty: %08" PRIx32 "\n", info->channels[i].channel, info->channels[i].duty); } #else pwminfo(" duty: %08" PRIx32 "\n", info->duty); #endif #ifdef CONFIG_PWM_PULSECOUNT pwminfo(" count: %" PRIx32 "\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 = nxmutex_lock(&upper->lock); 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_lock; } /* 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_lock; } } /* Save the new open count on success */ upper->crefs = tmp; ret = OK; errout_with_lock: nxmutex_unlock(&upper->lock); 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 = nxmutex_lock(&upper->lock); 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\n"); lower->ops->shutdown(lower); } ret = OK; nxmutex_unlock(&upper->lock); 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. */ ret = nxsem_wait_uninterruptible(&upper->waitsem); if (ret < 0) { upper->started = false; upper->waiting = false; } } } 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 = nxmutex_lock(&upper->lock); 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; } nxmutex_unlock(&upper->lock); 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()). */ nxmutex_init(&upper->lock); #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_set_protocol(&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() method 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 */