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ardupilot/libraries/AP_HAL_Linux/UARTDriver.cpp

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#include <AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
#include "UARTDriver.h"
#include <stdio.h>
#include <errno.h>
#include <termios.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <poll.h>
#include <assert.h>
#include <sys/ioctl.h>
extern const AP_HAL::HAL& hal;
using namespace Linux;
LinuxUARTDriver::LinuxUARTDriver(bool default_console) :
device_path(NULL),
_rd_fd(-1),
_wr_fd(-1)
{
if (default_console) {
_rd_fd = 0;
_wr_fd = 1;
_console = true;
}
}
/*
set the tty device to use for this UART
*/
void LinuxUARTDriver::set_device_path(const char *path)
{
device_path = path;
}
/*
open the tty
*/
void LinuxUARTDriver::begin(uint32_t b)
{
begin(b, 0, 0);
}
void LinuxUARTDriver::begin(uint32_t b, uint16_t rxS, uint16_t txS)
{
if (device_path == NULL && _console) {
_rd_fd = 0;
_wr_fd = 1;
rxS = 512;
txS = 512;
fcntl(_rd_fd, F_SETFL, fcntl(_rd_fd, F_GETFL, 0) | O_NONBLOCK);
fcntl(_wr_fd, F_SETFL, fcntl(_wr_fd, F_GETFL, 0) | O_NONBLOCK);
} else if (!_initialised) {
if (device_path == NULL) {
return;
}
uint8_t retries = 0;
while (retries < 5) {
_rd_fd = open(device_path, O_RDWR);
if (_rd_fd != -1) {
break;
}
// sleep a bit and retry. There seems to be a NuttX bug
// that can cause ttyACM0 to not be available immediately,
// but a small delay can fix it
hal.scheduler->delay(100);
retries++;
}
_wr_fd = _rd_fd;
if (_rd_fd == -1) {
fprintf(stdout, "Failed to open UART device %s - %s\n",
device_path, strerror(errno));
return;
}
if (retries != 0) {
fprintf(stdout, "WARNING: took %u retries to open UART %s\n",
(unsigned)retries, device_path);
return;
}
// always run the file descriptor non-blocking, and deal with
// blocking IO in the higher level calls
fcntl(_rd_fd, F_SETFL, fcntl(_rd_fd, F_GETFL, 0) | O_NONBLOCK);
if (rxS < 1024) {
rxS = 1024;
}
// we have enough memory to have a larger transmit buffer for
// all ports. This means we don't get delays while waiting to
// write GPS config packets
if (txS < 1024) {
txS = 1024;
}
}
_initialised = false;
while (_in_timer) hal.scheduler->delay(1);
if (b != 0 && _rd_fd == _wr_fd) {
// set the baud rate
struct termios t;
tcgetattr(_rd_fd, &t);
cfsetspeed(&t, b);
// disable LF -> CR/LF
t.c_oflag &= ~ONLCR;
tcsetattr(_rd_fd, TCSANOW, &t);
}
/*
allocate the read buffer
*/
if (rxS != 0 && rxS != _readbuf_size) {
_readbuf_size = rxS;
if (_readbuf != NULL) {
free(_readbuf);
}
_readbuf = (uint8_t *)malloc(_readbuf_size);
_readbuf_head = 0;
_readbuf_tail = 0;
}
/*
allocate the write buffer
*/
if (txS != 0 && txS != _writebuf_size) {
_writebuf_size = txS;
if (_writebuf != NULL) {
free(_writebuf);
}
_writebuf = (uint8_t *)malloc(_writebuf_size+16);
_writebuf_head = 0;
_writebuf_tail = 0;
}
if (_writebuf_size != 0 && _readbuf_size != 0) {
_initialised = true;
}
}
/*
shutdown a UART
*/
void LinuxUARTDriver::end()
{
_initialised = false;
while (_in_timer) hal.scheduler->delay(1);
if (_rd_fd == _wr_fd && _rd_fd != -1) {
close(_rd_fd);
}
_rd_fd = -1;
_wr_fd = -1;
if (_readbuf) {
free(_readbuf);
_readbuf = NULL;
}
if (_writebuf) {
free(_writebuf);
_writebuf = NULL;
}
_readbuf_size = _writebuf_size = 0;
_writebuf_head = 0;
_writebuf_tail = 0;
_readbuf_head = 0;
_readbuf_tail = 0;
}
void LinuxUARTDriver::flush()
{
// we are not doing any buffering, so flush is a no-op
}
/*
return true if the UART is initialised
*/
bool LinuxUARTDriver::is_initialized()
{
return _initialised;
}
/*
enable or disable blocking writes
*/
void LinuxUARTDriver::set_blocking_writes(bool blocking)
{
_nonblocking_writes = !blocking;
}
/*
buffer handling macros
*/
#define BUF_AVAILABLE(buf) ((buf##_head > (_tail=buf##_tail))? (buf##_size - buf##_head) + _tail: _tail - buf##_head)
#define BUF_SPACE(buf) (((_head=buf##_head) > buf##_tail)?(_head - buf##_tail) - 1:((buf##_size - buf##_tail) + _head) - 1)
#define BUF_EMPTY(buf) (buf##_head == buf##_tail)
#define BUF_ADVANCETAIL(buf, n) buf##_tail = (buf##_tail + n) % buf##_size
#define BUF_ADVANCEHEAD(buf, n) buf##_head = (buf##_head + n) % buf##_size
/*
do we have any bytes pending transmission?
*/
bool LinuxUARTDriver::tx_pending()
{
return !BUF_EMPTY(_writebuf);
}
/*
return the number of bytes available to be read
*/
int16_t LinuxUARTDriver::available()
{
if (!_initialised) {
return 0;
}
uint16_t _tail;
return BUF_AVAILABLE(_readbuf);
}
/*
how many bytes are available in the output buffer?
*/
int16_t LinuxUARTDriver::txspace()
{
if (!_initialised) {
return 0;
}
uint16_t _head;
return BUF_SPACE(_writebuf);
}
int16_t LinuxUARTDriver::read()
{
uint8_t c;
if (!_initialised || _readbuf == NULL) {
return -1;
}
if (BUF_EMPTY(_readbuf)) {
return -1;
}
c = _readbuf[_readbuf_head];
BUF_ADVANCEHEAD(_readbuf, 1);
return c;
}
/* Linux implementations of Print virtual methods */
size_t LinuxUARTDriver::write(uint8_t c)
{
if (!_initialised) {
return 0;
}
uint16_t _head;
while (BUF_SPACE(_writebuf) == 0) {
if (_nonblocking_writes) {
return 0;
}
hal.scheduler->delay(1);
}
_writebuf[_writebuf_tail] = c;
BUF_ADVANCETAIL(_writebuf, 1);
return 1;
}
/*
write size bytes to the write buffer
*/
size_t LinuxUARTDriver::write(const uint8_t *buffer, size_t size)
{
if (!_initialised) {
return 0;
}
if (!_nonblocking_writes) {
/*
use the per-byte delay loop in write() above for blocking writes
*/
size_t ret = 0;
while (size--) {
if (write(*buffer++) != 1) break;
ret++;
}
return ret;
}
uint16_t _head, space;
space = BUF_SPACE(_writebuf);
if (space == 0) {
return 0;
}
if (size > space) {
size = space;
}
if (_writebuf_tail < _head) {
// perform as single memcpy
assert(_writebuf_tail+size <= _writebuf_size);
memcpy(&_writebuf[_writebuf_tail], buffer, size);
BUF_ADVANCETAIL(_writebuf, size);
return size;
}
// perform as two memcpy calls
uint16_t n = _writebuf_size - _writebuf_tail;
if (n > size) n = size;
assert(_writebuf_tail+n <= _writebuf_size);
memcpy(&_writebuf[_writebuf_tail], buffer, n);
BUF_ADVANCETAIL(_writebuf, n);
buffer += n;
n = size - n;
if (n > 0) {
assert(_writebuf_tail+n <= _writebuf_size);
memcpy(&_writebuf[_writebuf_tail], buffer, n);
BUF_ADVANCETAIL(_writebuf, n);
}
return size;
}
/*
try writing n bytes, handling an unresponsive port
*/
int LinuxUARTDriver::_write_fd(const uint8_t *buf, uint16_t n)
{
int ret = 0;
struct pollfd fds;
fds.fd = _wr_fd;
fds.events = POLLOUT;
fds.revents = 0;
if (poll(&fds, 1, 0) == 1) {
ret = ::write(_wr_fd, buf, n);
}
if (ret > 0) {
BUF_ADVANCEHEAD(_writebuf, ret);
return ret;
}
return ret;
}
/*
try reading n bytes, handling an unresponsive port
*/
int LinuxUARTDriver::_read_fd(uint8_t *buf, uint16_t n)
{
int ret;
ret = ::read(_rd_fd, buf, n);
if (ret > 0) {
BUF_ADVANCETAIL(_readbuf, ret);
}
return ret;
}
/*
push any pending bytes to/from the serial port. This is called at
1kHz in the timer thread. Doing it this way reduces the system call
overhead in the main task enormously.
*/
void LinuxUARTDriver::_timer_tick(void)
{
uint16_t n;
if (!_initialised) return;
_in_timer = true;
// write any pending bytes
uint16_t _tail;
n = BUF_AVAILABLE(_writebuf);
if (n > 0) {
if (_tail > _writebuf_head) {
// do as a single write
_write_fd(&_writebuf[_writebuf_head], n);
} else {
// split into two writes
uint16_t n1 = _writebuf_size - _writebuf_head;
int ret = _write_fd(&_writebuf[_writebuf_head], n1);
if (ret == n1 && n != n1) {
_write_fd(&_writebuf[_writebuf_head], n - n1);
}
}
}
// try to fill the read buffer
uint16_t _head;
n = BUF_SPACE(_readbuf);
if (n > 0) {
if (_readbuf_tail < _head) {
// one read will do
assert(_readbuf_tail+n <= _readbuf_size);
_read_fd(&_readbuf[_readbuf_tail], n);
} else {
uint16_t n1 = _readbuf_size - _readbuf_tail;
assert(_readbuf_tail+n1 <= _readbuf_size);
int ret = _read_fd(&_readbuf[_readbuf_tail], n1);
if (ret == n1 && n != n1) {
assert(_readbuf_tail+(n-n1) <= _readbuf_size);
_read_fd(&_readbuf[_readbuf_tail], n - n1);
}
}
}
_in_timer = false;
}
#endif // CONFIG_HAL_BOARD
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