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/**
* @brief "Bottom" of native tty uart driver
*
* Copyright (c) 2023 Marko Sagadin
* SPDX-License-Identifier: Apache-2.0
*/
#include "uart_native_tty_bottom.h"
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <termios.h>
#include <unistd.h>
#include <nsi_tracing.h>
#define WARN(...) nsi_print_warning(__VA_ARGS__)
#define ERROR(...) nsi_print_error_and_exit(__VA_ARGS__)
#define ARRAY_SIZE(array) (sizeof(array) / sizeof((array)[0]))
struct baudrate_termios_pair {
int baudrate;
speed_t termios_baudrate;
};
/**
* @brief Lookup table for mapping the baud rate to the macro understood by termios.
*/
static const struct baudrate_termios_pair baudrate_lut[] = {
{1200, B1200}, {1800, B1800}, {2400, B2400}, {4800, B4800},
{9600, B9600}, {19200, B19200}, {38400, B38400}, {57600, B57600},
{115200, B115200}, {230400, B230400}, {460800, B460800}, {500000, B500000},
{576000, B576000}, {921600, B921600}, {1000000, B1000000}, {1152000, B1152000},
{1500000, B1500000}, {2000000, B2000000}, {2500000, B2500000}, {3000000, B3000000},
{3500000, B3500000}, {4000000, B4000000},
};
/**
* @brief Set given termios to defaults appropriate for communicating with serial port devices.
*
* @param ter
*/
static inline void native_tty_termios_defaults_set(struct termios *ter)
{
/* Set terminal in "serial" mode:
* - Not canonical (no line input)
* - No signal generation from Ctr+{C|Z..}
* - No echoing
*/
ter->c_lflag &= ~(ICANON | ISIG | ECHO);
/* No special interpretation of output bytes.
* No conversion of newline to carriage return/line feed.
*/
ter->c_oflag &= ~(OPOST | ONLCR);
/* No software flow control. */
ter->c_iflag &= ~(IXON | IXOFF | IXANY);
/* No blocking, return immediately with what is available. */
ter->c_cc[VMIN] = 0;
ter->c_cc[VTIME] = 0;
/* No special handling of bytes on receive. */
ter->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL);
/* - Enable reading data and ignore control lines */
ter->c_cflag |= CREAD | CLOCAL;
}
/**
* @brief Set the baud rate speed in the termios structure
*
* @param ter
* @param baudrate
*/
static inline void native_tty_baud_speed_set(struct termios *ter, int baudrate)
{
for (int i = 0; i < ARRAY_SIZE(baudrate_lut); i++) {
if (baudrate_lut[i].baudrate == baudrate) {
cfsetospeed(ter, baudrate_lut[i].termios_baudrate);
cfsetispeed(ter, baudrate_lut[i].termios_baudrate);
return;
}
}
ERROR("Could not set baudrate, as %d is not supported.\n", baudrate);
}
/**
* @brief Set parity setting in the termios structure
*
* @param ter
* @param parity
*/
static inline void native_tty_baud_parity_set(struct termios *ter,
enum native_tty_bottom_parity parity)
{
switch (parity) {
case NTB_PARITY_NONE:
ter->c_cflag &= ~PARENB;
break;
case NTB_PARITY_ODD:
ter->c_cflag |= PARENB;
ter->c_cflag |= PARODD;
break;
case NTB_PARITY_EVEN:
ter->c_cflag |= PARENB;
ter->c_cflag &= ~PARODD;
break;
default:
/* Parity options mark and space are not supported on this driver. */
ERROR("Could not set parity.\n");
}
}
/**
* @brief Set the number of stop bits in the termios structure
*
* @param ter
* @param stop_bits
*
*/
static inline void native_tty_stop_bits_set(struct termios *ter,
enum native_tty_bottom_stop_bits stop_bits)
{
switch (stop_bits) {
case NTB_STOP_BITS_1:
ter->c_cflag &= ~CSTOPB;
break;
case NTB_STOP_BITS_2:
ter->c_cflag |= CSTOPB;
break;
default:
/* Anything else is not supported in termios. */
ERROR("Could not set number of data bits.\n");
}
}
/**
* @brief Set the number of data bits in the termios structure
*
* @param ter
* @param data_bits
*
*/
static inline void native_tty_data_bits_set(struct termios *ter,
enum native_tty_bottom_data_bits data_bits)
{
unsigned int data_bits_to_set = CS5;
switch (data_bits) {
case NTB_DATA_BITS_5:
data_bits_to_set = CS5;
break;
case NTB_DATA_BITS_6:
data_bits_to_set = CS6;
break;
case NTB_DATA_BITS_7:
data_bits_to_set = CS7;
break;
case NTB_DATA_BITS_8:
data_bits_to_set = CS8;
break;
default:
/* Anything else is not supported in termios */
ERROR("Could not set number of data bits.\n");
}
/* Clear all bits that set the data size */
ter->c_cflag &= ~CSIZE;
ter->c_cflag |= data_bits_to_set;
}
int native_tty_poll_bottom(int fd)
{
struct pollfd pfd = { .fd = fd, .events = POLLIN };
return poll(&pfd, 1, 0);
}
int native_tty_open_tty_bottom(const char *pathname)
{
int fd = open(pathname, O_RDWR | O_NOCTTY);
if (fd < 0) {
ERROR("Failed to open serial port %s, errno: %i\n", pathname, errno);
}
return fd;
}
int native_tty_configure_bottom(int fd, struct native_tty_bottom_cfg *cfg)
{
int rc, err;
/* Structure used to control properties of a serial port */
struct termios ter;
/* Read current terminal driver settings */
rc = tcgetattr(fd, &ter);
if (rc) {
WARN("Could not read terminal driver settings\n");
return rc;
}
native_tty_termios_defaults_set(&ter);
native_tty_baud_speed_set(&ter, cfg->baudrate);
native_tty_baud_parity_set(&ter, cfg->parity);
native_tty_stop_bits_set(&ter, cfg->stop_bits);
native_tty_data_bits_set(&ter, cfg->data_bits);
cfg->flow_ctrl = NTB_FLOW_CTRL_NONE;
rc = tcsetattr(fd, TCSANOW, &ter);
if (rc) {
err = errno;
WARN("Could not set serial port settings, reason: %s\n", strerror(err));
return err;
}
/* tcsetattr returns success if ANY of the requested changes were successfully carried out,
* not if ALL were. So we need to read back the settings and check if they are equal to the
* requested ones.
*/
struct termios read_ter;
rc = tcgetattr(fd, &read_ter);
if (rc) {
err = errno;
WARN("Could not read serial port settings, reason: %s\n", strerror(err));
return err;
}
if (ter.c_cflag != read_ter.c_cflag || ter.c_iflag != read_ter.c_iflag ||
ter.c_oflag != read_ter.c_oflag || ter.c_lflag != read_ter.c_lflag ||
ter.c_line != read_ter.c_line || ter.c_ispeed != read_ter.c_ispeed ||
ter.c_ospeed != read_ter.c_ospeed || 0 != memcmp(ter.c_cc, read_ter.c_cc, NCCS)) {
WARN("Read serial port settings do not match set ones.\n");
return -1;
}
/* Flush both input and output */
rc = tcflush(fd, TCIOFLUSH);
if (rc) {
WARN("Could not flush serial port\n");
return rc;
}
return 0;
}