ardupilot/libraries/AP_HAL_PX4/UARTDriver.cpp
Andrew Tridgell 2340bb6220 PX4: use a minimum transmit buffer for UARTs of 512 bytes
this avoids writes stalling on the GPS port. We can't afford this
memory on APM2, but we can on PX4, and it means that while the GPS is
blocking at startup it doesn't cause any scheduler slips
2013-08-30 13:01:33 +10:00

479 lines
12 KiB
C++

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
#include <AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_PX4
#include "UARTDriver.h"
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <drivers/drv_hrt.h>
#include <assert.h>
using namespace PX4;
extern const AP_HAL::HAL& hal;
PX4UARTDriver::PX4UARTDriver(const char *devpath, const char *perf_name) :
_devpath(devpath),
_perf_uart(perf_alloc(PC_ELAPSED, perf_name))
{}
extern const AP_HAL::HAL& hal;
/*
this UART driver maps to a serial device in /dev
*/
void PX4UARTDriver::begin(uint32_t b, uint16_t rxS, uint16_t txS)
{
if (!_initialised) {
uint8_t retries = 0;
while (retries < 5) {
_fd = open(_devpath, O_RDWR);
if (_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++;
}
if (_fd == -1) {
fprintf(stdout, "Failed to open UART device %s - %s\n",
_devpath, strerror(errno));
return;
}
if (retries != 0) {
fprintf(stdout, "WARNING: took %u retries to open UART %s\n",
(unsigned)retries, _devpath);
return;
}
if (rxS == 0) {
rxS = 128;
}
// on PX4 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 < 512) {
txS = 512;
}
}
_initialised = false;
while (_in_timer) hal.scheduler->delay(1);
if (b != 0) {
// set the baud rate
struct termios t;
tcgetattr(_fd, &t);
cfsetspeed(&t, b);
// disable LF -> CR/LF
t.c_oflag &= ~ONLCR;
tcsetattr(_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;
}
}
void PX4UARTDriver::begin(uint32_t b)
{
begin(b, 0, 0);
}
void PX4UARTDriver::end() {}
void PX4UARTDriver::flush() {}
bool PX4UARTDriver::is_initialized() { return true; }
void PX4UARTDriver::set_blocking_writes(bool blocking)
{
_nonblocking_writes = !blocking;
}
bool PX4UARTDriver::tx_pending() { return false; }
/* PX4 implementations of BetterStream virtual methods */
void PX4UARTDriver::print_P(const prog_char_t *pstr) {
print(pstr);
}
void PX4UARTDriver::println_P(const prog_char_t *pstr) {
println(pstr);
}
void PX4UARTDriver::printf(const char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
_vprintf(fmt, ap);
va_end(ap);
}
void PX4UARTDriver::_printf_P(const prog_char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
_vprintf(fmt, ap);
va_end(ap);
}
void PX4UARTDriver::vprintf(const char *fmt, va_list ap) {
_vprintf(fmt, ap);
}
void PX4UARTDriver::vprintf_P(const prog_char *fmt, va_list ap) {
_vprintf(fmt, ap);
}
void PX4UARTDriver::_internal_vprintf(const char *fmt, va_list ap)
{
if (hal.scheduler->in_timerprocess()) {
// not allowed from timers
return;
}
char *buf = NULL;
int n = avsprintf(&buf, fmt, ap);
if (n > 0) {
write((const uint8_t *)buf, n);
}
if (buf != NULL) {
free(buf);
}
}
// handle %S -> %s
void PX4UARTDriver::_vprintf(const char *fmt, va_list ap)
{
if (hal.scheduler->in_timerprocess()) {
// not allowed from timers
return;
}
// we don't use vdprintf() as it goes directly to the file descriptor
if (strstr(fmt, "%S")) {
char *fmt2 = strdup(fmt);
if (fmt2 != NULL) {
for (uint16_t i=0; fmt2[i]; i++) {
if (fmt2[i] == '%' && fmt2[i+1] == 'S') {
fmt2[i+1] = 's';
}
}
_internal_vprintf(fmt2, ap);
free(fmt2);
}
} else {
_internal_vprintf(fmt, ap);
}
}
/*
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
/*
return number of bytes available to be read from the buffer
*/
int16_t PX4UARTDriver::available()
{
if (!_initialised) {
return 0;
}
uint16_t _tail;
return BUF_AVAILABLE(_readbuf);
}
/*
return number of bytes that can be added to the write buffer
*/
int16_t PX4UARTDriver::txspace()
{
if (!_initialised) {
return 0;
}
uint16_t _head;
return BUF_SPACE(_writebuf);
}
/*
read one byte from the read buffer
*/
int16_t PX4UARTDriver::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;
}
/*
write one byte to the buffer
*/
size_t PX4UARTDriver::write(uint8_t c)
{
if (!_initialised) {
return 0;
}
if (hal.scheduler->in_timerprocess()) {
// not allowed from timers
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 PX4UARTDriver::write(const uint8_t *buffer, size_t size)
{
if (!_initialised) {
return 0;
}
if (hal.scheduler->in_timerprocess()) {
// not allowed from timers
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 PX4UARTDriver::_write_fd(const uint8_t *buf, uint16_t n)
{
int ret = 0;
// the FIONWRITE check is to cope with broken O_NONBLOCK behaviour
// in NuttX on ttyACM0
int nwrite = 0;
if (ioctl(_fd, FIONWRITE, (unsigned long)&nwrite) == 0) {
if (nwrite > n) {
nwrite = n;
}
if (nwrite > 0) {
ret = ::write(_fd, buf, nwrite);
}
}
if (ret > 0) {
BUF_ADVANCEHEAD(_writebuf, ret);
_last_write_time = hrt_absolute_time();
return ret;
}
if (hrt_absolute_time() - _last_write_time > 2000) {
#if 0
// this trick is disabled for now, as it sometimes blocks on
// re-opening the ttyACM0 port, which would cause a crash
if (hrt_absolute_time() - _last_write_time > 2000000) {
// we haven't done a successful write for 2 seconds - try
// reopening the port
_initialised = false;
::close(_fd);
_fd = ::open(_devpath, O_RDWR);
if (_fd == -1) {
fprintf(stdout, "Failed to reopen UART device %s - %s\n",
_devpath, strerror(errno));
// leave it uninitialised
return n;
}
_last_write_time = hrt_absolute_time();
_initialised = true;
}
#else
_last_write_time = hrt_absolute_time();
#endif
// we haven't done a successful write for 2ms, which means the
// port is running at less than 500 bytes/sec. Start
// discarding bytes, even if this is a blocking port. This
// prevents the ttyACM0 port blocking startup if the endpoint
// is not connected
BUF_ADVANCEHEAD(_writebuf, n);
return n;
}
return ret;
}
/*
try reading n bytes, handling an unresponsive port
*/
int PX4UARTDriver::_read_fd(uint8_t *buf, uint16_t n)
{
int ret = 0;
// the FIONREAD check is to cope with broken O_NONBLOCK behaviour
// in NuttX on ttyACM0
int nread = 0;
if (ioctl(_fd, FIONREAD, (unsigned long)&nread) == 0) {
if (nread > n) {
nread = n;
}
if (nread > 0) {
ret = ::read(_fd, buf, nread);
}
}
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 PX4UARTDriver::_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) {
perf_begin(_perf_uart);
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);
}
}
perf_end(_perf_uart);
}
// try to fill the read buffer
uint16_t _head;
n = BUF_SPACE(_readbuf);
if (n > 0) {
perf_begin(_perf_uart);
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);
}
}
perf_end(_perf_uart);
}
_in_timer = false;
}
#endif // CONFIG_HAL_BOARD