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incubator-nuttx/drivers/analog/adc.c

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/****************************************************************************
* drivers/analog/adc.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 <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/fs/fs.h>
#include <nuttx/arch.h>
#include <nuttx/analog/adc.h>
#include <nuttx/analog/ioctl.h>
#include <nuttx/random.h>
#include <nuttx/irq.h>
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int adc_open(FAR struct file *filep);
static int adc_close(FAR struct file *filep);
static ssize_t adc_read(FAR struct file *fielp, FAR char *buffer,
size_t buflen);
static int adc_ioctl(FAR struct file *filep, int cmd, unsigned long arg);
static int adc_reset(FAR struct adc_dev_s *dev);
static int adc_receive(FAR struct adc_dev_s *dev, uint8_t ch,
int32_t data);
static void adc_notify(FAR struct adc_dev_s *dev);
static int adc_poll(FAR struct file *filep, struct pollfd *fds,
bool setup);
static int adc_reset_fifo(FAR struct adc_dev_s *dev);
static int adc_samples_on_read(FAR struct adc_dev_s *dev);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_adc_fops =
{
adc_open, /* open */
adc_close, /* close */
adc_read, /* read */
NULL, /* write */
NULL, /* seek */
adc_ioctl, /* ioctl */
NULL, /* mmap */
NULL, /* truncate */
adc_poll /* poll */
};
static const struct adc_callback_s g_adc_callback =
{
adc_receive, /* au_receive */
adc_reset /* au_reset */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: adc_open
*
* Description:
* This function is called whenever the ADC device is opened.
*
****************************************************************************/
static int adc_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct adc_dev_s *dev = inode->i_private;
uint8_t tmp;
int ret;
/* If the port is the middle of closing, wait until the close is
* finished.
*/
ret = nxmutex_lock(&dev->ad_closelock);
if (ret >= 0)
{
/* 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 = dev->ad_ocount + 1;
if (tmp == 0)
{
/* More than 255 opens; uint8_t overflows to zero */
ret = -EMFILE;
}
else
{
/* Check if this is the first time that the driver has been
* opened.
*/
if (tmp == 1)
{
/* Yes.. perform one time hardware initialization. */
irqstate_t flags = enter_critical_section();
ret = dev->ad_ops->ao_setup(dev);
if (ret == OK)
{
/* Mark the FIFOs empty */
dev->ad_recv.af_head = 0;
dev->ad_recv.af_tail = 0;
/* Clear overrun indicator */
dev->ad_isovr = false;
/* Finally, Enable the ADC RX interrupt */
dev->ad_ops->ao_rxint(dev, true);
}
leave_critical_section(flags);
}
/* Save the new open count on success */
dev->ad_ocount = tmp;
}
nxmutex_unlock(&dev->ad_closelock);
}
return ret;
}
/****************************************************************************
* Name: adc_close
*
* Description:
* This routine is called when the ADC device is closed.
* It waits for the last remaining data to be sent.
*
****************************************************************************/
static int adc_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct adc_dev_s *dev = inode->i_private;
irqstate_t flags;
int ret;
ret = nxmutex_lock(&dev->ad_closelock);
if (ret >= 0)
{
/* Decrement the references to the driver. If the reference count will
* decrement to 0, then uninitialize the driver.
*/
if (dev->ad_ocount > 1)
{
dev->ad_ocount--;
nxmutex_unlock(&dev->ad_closelock);
}
else
{
/* There are no more references to the port */
dev->ad_ocount = 0;
/* Free the IRQ and disable the ADC device */
flags = enter_critical_section(); /* Disable interrupts */
dev->ad_ops->ao_shutdown(dev); /* Disable the ADC */
leave_critical_section(flags);
nxmutex_unlock(&dev->ad_closelock);
}
}
return ret;
}
/****************************************************************************
* Name: adc_read
****************************************************************************/
static ssize_t adc_read(FAR struct file *filep, FAR char *buffer,
size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR struct adc_dev_s *dev = inode->i_private;
size_t nread;
irqstate_t flags;
int ret = 0;
int msglen;
ainfo("buflen: %d\n", (int)buflen);
/* Determine the size of the messages to return.
*
* REVISIT: What if buflen is 8 does that mean 4 messages of size 2? Or
* 2 messages of size 4? What if buflen is 12. Does that mean 3 at size
* 4? Or 4 at size 3? The form of the return data should probably really
* be specified via IOCTL.
*/
if (buflen % 5 == 0)
{
msglen = 5;
}
else if (buflen % 4 == 0)
{
msglen = 4;
}
else if (buflen % 3 == 0)
{
msglen = 3;
}
else if (buflen % 2 == 0)
{
msglen = 2;
}
else if (buflen == 1)
{
msglen = 1;
}
else
{
msglen = 5;
}
if (buflen >= msglen)
{
/* Interrupts must be disabled while accessing the ad_recv FIFO */
flags = enter_critical_section();
while (dev->ad_recv.af_head == dev->ad_recv.af_tail)
{
/* Check if there was an overrun, if set we need to return EIO */
if (dev->ad_isovr)
{
dev->ad_isovr = false;
ret = -EIO;
goto return_with_irqdisabled;
}
/* The receive FIFO is empty -- was non-blocking mode selected? */
if (filep->f_oflags & O_NONBLOCK)
{
ret = -EAGAIN;
goto return_with_irqdisabled;
}
/* Wait for a message to be received */
dev->ad_nrxwaiters++;
ret = nxsem_wait(&dev->ad_recv.af_sem);
dev->ad_nrxwaiters--;
if (ret < 0)
{
goto return_with_irqdisabled;
}
}
/* The ad_recv FIFO is not empty. Copy all buffered data that will fit
* in the user buffer.
*/
nread = 0;
do
{
FAR struct adc_msg_s *msg =
&dev->ad_recv.af_buffer[dev->ad_recv.af_head];
/* Will the next message in the FIFO fit into the user buffer? */
if (nread + msglen > buflen)
{
/* No.. break out of the loop now with nread equal to the
* actual number of bytes transferred.
*/
break;
}
/* Feed ADC data to entropy pool */
add_sensor_randomness(msg->am_data);
/* Copy the message to the user buffer */
if (msglen == 1)
{
/* Only one channel, return MS 8-bits of the sample. */
buffer[nread] = msg->am_data >> 24;
}
else if (msglen == 2)
{
/* Only one channel, return only the MS 16-bits of the sample.
*/
int16_t data16 = msg->am_data >> 16;
memcpy(&buffer[nread], &data16, 2);
}
else if (msglen == 3)
{
int16_t data16;
/* Return the channel and the MS 16-bits of the sample. */
buffer[nread] = msg->am_channel;
data16 = msg->am_data >> 16;
memcpy(&buffer[nread + 1], &data16, 2);
}
else if (msglen == 4)
{
int32_t data24;
#ifdef CONFIG_ENDIAN_BIG
/* In the big endian case, we simply copy the MS three bytes
* which are indices: 0-2.
*/
data24 = msg->am_data;
#else
/* In the little endian case, indices 0-2 correspond to the
* the three LS bytes.
*/
data24 = msg->am_data >> 8;
#endif
/* Return the channel and the most significant 24-bits */
buffer[nread] = msg->am_channel;
memcpy(&buffer[nread + 1], &data24, 3);
}
else
{
/* Return the channel and all four bytes of the sample */
buffer[nread] = msg->am_channel;
memcpy(&buffer[nread + 1], &msg->am_data, 4);
}
nread += msglen;
/* Increment the head of the circular message buffer */
if (++dev->ad_recv.af_head >= CONFIG_ADC_FIFOSIZE)
{
dev->ad_recv.af_head = 0;
}
}
while (dev->ad_recv.af_head != dev->ad_recv.af_tail);
/* All of the messages have been transferred. Return the number of
* bytes that were read.
*/
ret = nread;
return_with_irqdisabled:
leave_critical_section(flags);
}
ainfo("Returning: %d\n", ret);
return ret;
}
/****************************************************************************
* Name: adc_ioctl
****************************************************************************/
static int adc_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct adc_dev_s *dev = inode->i_private;
int ret;
switch (cmd)
{
case ANIOC_RESET_FIFO:
{
ret = adc_reset_fifo(dev);
}
break;
case ANIOC_SAMPLES_ON_READ:
{
ret = adc_samples_on_read(dev);
}
break;
default:
{
/* Those IOCTLs might be used in arch specific section */
ret = dev->ad_ops->ao_ioctl(dev, cmd, arg);
}
break;
}
return ret;
}
/****************************************************************************
* Name: adc_reset
****************************************************************************/
static int adc_reset(FAR struct adc_dev_s *dev)
{
/* Set overrun flag to give read a chance to recover */
dev->ad_isovr = true;
/* No need to notify here. The adc_receive callback will be called next.
* If an ADC overrun occurs then there must be at least one conversion.
*/
return OK;
}
/****************************************************************************
* Name: adc_receive
****************************************************************************/
static int adc_receive(FAR struct adc_dev_s *dev, uint8_t ch, int32_t data)
{
FAR struct adc_fifo_s *fifo = &dev->ad_recv;
int nexttail;
int errcode = -ENOMEM;
/* Check if adding this new message would over-run the drivers ability to
* enqueue read data.
*/
nexttail = fifo->af_tail + 1;
if (nexttail >= CONFIG_ADC_FIFOSIZE)
{
nexttail = 0;
}
/* Refuse the new data if the FIFO is full */
if (nexttail != fifo->af_head)
{
/* Add the new, decoded ADC sample at the tail of the FIFO */
fifo->af_buffer[fifo->af_tail].am_channel = ch;
fifo->af_buffer[fifo->af_tail].am_data = data;
/* Increment the tail of the circular buffer */
fifo->af_tail = nexttail;
adc_notify(dev);
errcode = OK;
}
return errcode;
}
/****************************************************************************
* Name: adc_notify
****************************************************************************/
static void adc_notify(FAR struct adc_dev_s *dev)
{
FAR struct adc_fifo_s *fifo = &dev->ad_recv;
/* If there are threads waiting on poll() for data to become available,
* then wake them up now.
*/
poll_notify(dev->fds, CONFIG_ADC_NPOLLWAITERS, POLLIN);
/* If there are threads waiting for read data, then signal one of them
* that the read data is available.
*/
if (dev->ad_nrxwaiters > 0)
{
nxsem_post(&fifo->af_sem);
}
}
/****************************************************************************
* Name: adc_poll
****************************************************************************/
static int adc_poll(FAR struct file *filep, struct pollfd *fds, bool setup)
{
FAR struct inode *inode = filep->f_inode;
FAR struct adc_dev_s *dev = inode->i_private;
irqstate_t flags;
int ret = 0;
int i;
/* Interrupts must be disabled while accessing the list of poll structures
* and ad_recv FIFO.
*/
flags = enter_critical_section();
if (setup)
{
/* Ignore waits that do not include POLLIN */
if ((fds->events & POLLIN) == 0)
{
ret = -EDEADLK;
goto return_with_irqdisabled;
}
/* This is a request to set up the poll. Find an available
* slot for the poll structure reference
*/
for (i = 0; i < CONFIG_ADC_NPOLLWAITERS; i++)
{
/* Find an available slot */
if (!dev->fds[i])
{
/* Bind the poll structure and this slot */
dev->fds[i] = fds;
fds->priv = &dev->fds[i];
break;
}
}
if (i >= CONFIG_ADC_NPOLLWAITERS)
{
fds->priv = NULL;
ret = -EBUSY;
goto return_with_irqdisabled;
}
/* Should we immediately notify on any of the requested events? */
if (dev->ad_recv.af_head != dev->ad_recv.af_tail)
{
poll_notify(&fds, 1, POLLIN);
}
}
else if (fds->priv)
{
/* This is a request to tear down the poll. */
struct pollfd **slot = (struct pollfd **)fds->priv;
/* Remove all memory of the poll setup */
*slot = NULL;
fds->priv = NULL;
}
return_with_irqdisabled:
leave_critical_section(flags);
return ret;
}
/****************************************************************************
* Name: adc_reset_fifo
****************************************************************************/
static int adc_reset_fifo(FAR struct adc_dev_s *dev)
{
irqstate_t flags;
FAR struct adc_fifo_s *fifo = &dev->ad_recv;
/* Interrupts must be disabled while accessing the ad_recv FIFO */
flags = enter_critical_section();
fifo->af_head = fifo->af_tail;
leave_critical_section(flags);
return OK;
}
/****************************************************************************
* Name: adc_samples_on_read
****************************************************************************/
static int adc_samples_on_read(FAR struct adc_dev_s *dev)
{
irqstate_t flags;
FAR struct adc_fifo_s *fifo = &dev->ad_recv;
int16_t ret;
/* Interrupts must be disabled while accessing the ad_recv FIFO */
flags = enter_critical_section();
ret = fifo->af_tail - fifo->af_head;
leave_critical_section(flags);
if (ret < 0)
{
/* Increment return value by the size of FIFO */
ret += CONFIG_ADC_FIFOSIZE;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: adc_register
****************************************************************************/
int adc_register(FAR const char *path, FAR struct adc_dev_s *dev)
{
int ret;
DEBUGASSERT(path != NULL && dev != NULL);
/* Bind the upper-half callbacks to the lower half ADC driver */
DEBUGASSERT(dev->ad_ops != NULL && dev->ad_ops->ao_bind != NULL);
ret = dev->ad_ops->ao_bind(dev, &g_adc_callback);
if (ret < 0)
{
aerr("ERROR: Failed to bind callbacks: %d\n", ret);
return ret;
}
/* Initialize the ADC device structure */
dev->ad_ocount = 0;
/* Initialize semaphores & mutex */
nxsem_init(&dev->ad_recv.af_sem, 0, 0);
nxmutex_init(&dev->ad_closelock);
/* Reset the ADC hardware */
DEBUGASSERT(dev->ad_ops->ao_reset != NULL);
dev->ad_ops->ao_reset(dev);
/* Register the ADC character driver */
ret = register_driver(path, &g_adc_fops, 0444, dev);
if (ret < 0)
{
nxsem_destroy(&dev->ad_recv.af_sem);
nxmutex_destroy(&dev->ad_closelock);
}
return ret;
}
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