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author | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2011-12-16 16:17:34 +0000 |
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committer | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2011-12-16 16:17:34 +0000 |
commit | c41819ee0fa00a0741388d2b02edb370a1360a30 (patch) | |
tree | 300bc4957f4a2559432a2f6ae680ee6ccd8f3c7c /nuttx/drivers/pwm.c | |
parent | b081b723a309bbe18fbbb0f25dbf86c33c2df891 (diff) | |
download | px4-nuttx-c41819ee0fa00a0741388d2b02edb370a1360a30.tar.gz px4-nuttx-c41819ee0fa00a0741388d2b02edb370a1360a30.tar.bz2 px4-nuttx-c41819ee0fa00a0741388d2b02edb370a1360a30.zip |
Add generic, upper-half PWM driver
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4191 42af7a65-404d-4744-a932-0658087f49c3
Diffstat (limited to 'nuttx/drivers/pwm.c')
-rw-r--r-- | nuttx/drivers/pwm.c | 422 |
1 files changed, 422 insertions, 0 deletions
diff --git a/nuttx/drivers/pwm.c b/nuttx/drivers/pwm.c new file mode 100644 index 000000000..c870adfe4 --- /dev/null +++ b/nuttx/drivers/pwm.c @@ -0,0 +1,422 @@ +/**************************************************************************** + * drivers/pwm.c + * + * Copyright (C) 2011 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. + * + ****************************************************************************/ + +/**************************************************************************** + * Compilation Switches + ****************************************************************************/ + +/**************************************************************************** + * 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/fs.h> +#include <nuttx/arch.h> +#include <nuttx/pwm.h> + +#include <arch/irq.h> + +#ifdef CONFIG_PWM + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Type Definitions + ****************************************************************************/ + +/* This structure describes the state of the upper half drivere */ + +struct pwm_upperhalf_s +{ + uint8_t crefs; /* The number of times the device has been opened */ + bool started; /* True: pulsed output is being generated */ + sem_t sem; /* Supports mutual exclusion */ + struct pwm_info_s info; /* Pulsed output characteristics */ + FAR struct pwm_lowerhalf_s *dev; /* lower-half state */ +}; + +/**************************************************************************** + * Private Function Prototypes + ****************************************************************************/ + +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_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_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; + + /* Get exclusive access to the device structures */ + + ret = sem_wait(&upper->sem); + if (ret < 0) + { + ret = -errno; + 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. */ + + 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: + sem_post(&upper->sem); + +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; + + /* Get exclusive access to the device structures */ + + ret = sem_wait(&upper->sem); + if (ret < 0) + { + ret = -errno; + 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 */ + + lower->ops->shutdown(lower); + } + ret = OK; + +//errout_with_sem: + sem_post(&upper->sem); + +errout: + return ret; +} + +/************************************************************************************ + * Name: pwm_read + * + * Description: + * A dummy read method. This is provided only to satsify 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 satsify the VFS layer. + * + ************************************************************************************/ + +static ssize_t pwm_write(FAR struct file *filep, FAR const char *buffer, size_t buflen) +{ + return 0; +} + +/************************************************************************************ + * 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 = OK; + + /* 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); + memcpy(&upper->info, info, sizeof(struct pwm_info_s)); + if (upper->started) + { + ret = lower->ops->start(lower, &upper->info); + } + } + 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 recevie the + * characteristics of the pulsed output. + */ + + case PWMIOC_GETCHARACTERISTICS: + { + FAR struct pwm_info_s *info = (FAR struct pwm_info_s*)((uintptr_t)arg); + memcpy(info, &upper->info, sizeof(struct pwm_info_s)); + } + break; + + /* PWMIOC_START - Start the pulsed output. The PWMIOC_SETCHARACTERISTICS + * command must have previously been sent. + * + * ioctl argument: None + */ + + case PWMIOC_START: + { + if (!upper->started) + { + ret = lower->ops->start(lower, &upper->info); + upper->started = true; + } + } + break; + + /* PWMIOC_STOP - Stop the pulsed output. + * + * ioctl argument: None + */ + + case PWMIOC_STOP: + { + if (upper->started) + { + ret = lower->ops->stop(lower); + upper->started = false; + } + } + break; + + /* PWMIOC_GETPULSECOUNT - Return the number of pulses generated. + * + * ioctl argument: A pointer to a pwm_count_t variable that will be used to + * receive the pulse count + */ + + case PWMIOC_GETPULSECOUNT: + { + FAR pwm_count_t *count = (FAR pwm_count_t *)((uintptr_t)arg); + ret = lower->ops->pulsecount(lower, count); + } + break; + + /* Any unrecognized IOCTL commands might be platform-specific ioctl commands */ + + default: + { + ret = lower->ops->ioctl(lower, cmd, arg); + } + break; + } + 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 registers 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 *)zalloc(sizeof(struct pwm_upperhalf_s)); + if (!upper) + { + return -ENOMEM; + } + + /* Initialize the PWM device structure (it was already zeroed by zalloc()) */ + + sem_init(&upper->sem, 0, 1); + upper->dev = dev; + + /* Register the PWM device */ + + vdbg("Registering %s\n", path); + return register_driver(path, &g_pwmops, 0666, dev); +} + +#endif /* CONFIG_PWM */ |