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incubator-nuttx/drivers/sensors/qencoder.c

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/****************************************************************************
* drivers/sensors/qencoder.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 <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/arch.h>
#include <nuttx/semaphore.h>
#include <nuttx/sensors/qencoder.h>
#include <arch/irq.h>
#ifdef CONFIG_SENSORS_QENCODER
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Debug ********************************************************************/
/****************************************************************************
* Private Type Definitions
****************************************************************************/
/* This structure describes the state of the upper half driver */
struct qe_upperhalf_s
{
uint8_t crefs; /* The number of times the device has been opened */
sem_t exclsem; /* Supports mutual exclusion */
FAR struct qe_lowerhalf_s *lower; /* lower-half state */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int qe_open(FAR struct file *filep);
static int qe_close(FAR struct file *filep);
static ssize_t qe_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t qe_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int qe_ioctl(FAR struct file *filep, int cmd, unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_qeops =
{
qe_open, /* open */
qe_close, /* close */
qe_read, /* read */
qe_write, /* write */
NULL, /* seek */
qe_ioctl, /* ioctl */
NULL /* poll */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: qe_open
*
* Description:
* This function is called whenever the QEncoder device is opened.
*
****************************************************************************/
static int qe_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct qe_upperhalf_s *upper = inode->i_private;
uint8_t tmp;
int ret;
sninfo("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 is 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 qe_lowerhalf_s *lower = upper->lower;
/* Yes.. perform one time hardware initialization. */
DEBUGASSERT(lower->ops->setup != NULL);
sninfo("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: qe_close
*
* Description:
* This function is called when the QEncoder device is closed.
*
****************************************************************************/
static int qe_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct qe_upperhalf_s *upper = inode->i_private;
int ret;
sninfo("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 qe_lowerhalf_s *lower = upper->lower;
/* There are no more references to the port */
upper->crefs = 0;
/* Disable the QEncoder device */
DEBUGASSERT(lower->ops->shutdown != NULL);
sninfo("calling shutdown\n");
lower->ops->shutdown(lower);
}
nxsem_post(&upper->exclsem);
ret = OK;
errout:
return ret;
}
/****************************************************************************
* Name: qe_read
*
* Description:
* A dummy read method. This is provided only to satisfy the VFS layer.
*
****************************************************************************/
static ssize_t qe_read(FAR struct file *filep,
FAR char *buffer,
size_t buflen)
{
/* Return zero -- usually meaning end-of-file */
return 0;
}
/****************************************************************************
* Name: qe_write
*
* Description:
* A dummy write method. This is provided only to satisfy the VFS layer.
*
****************************************************************************/
static ssize_t qe_write(FAR struct file *filep,
FAR const char *buffer,
size_t buflen)
{
/* Return a failure */
return -EPERM;
}
/****************************************************************************
* Name: qe_ioctl
*
* Description:
* The standard ioctl method.
* This is where ALL of the QEncoder work is done.
*
****************************************************************************/
static int qe_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct qe_upperhalf_s *upper;
FAR struct qe_lowerhalf_s *lower;
int ret;
sninfo("cmd: %d arg: %ld\n", cmd, arg);
upper = inode->i_private;
DEBUGASSERT(upper != NULL);
lower = upper->lower;
DEBUGASSERT(lower != NULL);
/* Get exclusive access to the device structures */
ret = nxsem_wait(&upper->exclsem);
if (ret < 0)
{
return ret;
}
/* Handle built-in ioctl commands */
switch (cmd)
{
/* QEIOC_POSITION - Get the current position from the encoder.
* Argument: int32_t pointer to the location to return the position.
*/
case QEIOC_POSITION:
{
FAR int32_t *ptr = (FAR int32_t *)((uintptr_t)arg);
DEBUGASSERT(lower->ops->position != NULL && ptr);
ret = lower->ops->position(lower, ptr);
}
break;
/* QEIOC_RESET - Reset the position to zero.
* Argument: None
*/
case QEIOC_RESET:
{
DEBUGASSERT(lower->ops->reset != NULL);
ret = lower->ops->reset(lower);
}
break;
/* QEIOC_SETPOSMAX - Set the maximum encoder position.
* Argument: uint32
*/
case QEIOC_SETPOSMAX:
{
uint32_t maxpos = (uint32_t)arg;
if (lower->ops->setposmax != NULL)
{
ret = lower->ops->setposmax(lower, maxpos);
}
else
{
ret = -ENOTTY;
}
}
break;
/* Any unrecognized IOCTL commands might be platform-specific ioctl
* commands
*/
default:
{
sninfo("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: qe_register
*
* Description:
* Register the Quadrature Encoder lower half device as 'devpath'
*
* Input Parameters:
* devpath - The full path to the driver to register. E.g., "/dev/qe0"
* lower - An instance of the lower half interface
*
* Returned Value:
* Zero (OK) on success; a negated errno value on failure. The following
* possible error values may be returned (most are returned by
* register_driver()):
*
* EINVAL - 'path' is invalid for this operation
* EEXIST - An inode already exists at 'path'
* ENOMEM - Failed to allocate in-memory resources for the operation
*
****************************************************************************/
int qe_register(FAR const char *devpath, FAR struct qe_lowerhalf_s *lower)
{
FAR struct qe_upperhalf_s *upper;
/* Allocate the upper-half data structure */
upper = (FAR struct qe_upperhalf_s *)
kmm_zalloc(sizeof(struct qe_upperhalf_s));
if (!upper)
{
snerr("ERROR: Allocation failed\n");
return -ENOMEM;
}
/* Initialize the QEncoder device structure
* (it was already zeroed by kmm_zalloc())
*/
nxsem_init(&upper->exclsem, 0, 1);
upper->lower = lower;
/* Register the QEncoder device */
sninfo("Registering %s\n", devpath);
return register_driver(devpath, &g_qeops, 0666, upper);
}
#endif /* CONFIG_SENSORS_QENCODER */
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