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UART PTY: Add exit wait on readers #14

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UART PTY: Add exit wait on readers #14

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62 changes: 56 additions & 6 deletions src/HW_models/NHW_UART_backend_pty.c
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,13 @@
*/

#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <time.h>
#include <sys/ioctl.h>

int tcdrain(int fd);

#include "bs_types.h"
#include "bs_tracing.h"
#include "bs_oswrap.h"
Expand All @@ -47,6 +54,7 @@ struct upty_st_t {
bool auto_attach;
char *attach_cmd;
bool respect_RTS;
bool wait_for_readers;

int out_fd; /* File descriptor used for output */
int in_fd; /* File descriptor used for input */
Expand Down Expand Up @@ -206,18 +214,51 @@ static void nhw_upty_timer_triggered(void) {

NSI_HW_EVENT(Timer_UPTY, nhw_upty_timer_triggered, 900); /* Let's let as many timers as possible evaluate before this one */

static void nhw_upty_wait_for_fionread_empty(int fd) {
int bytes_left = 0;
const struct timespec sleep_time = { .tv_sec = 0, .tv_nsec = 1000000 }; // 1ms

while (1) {
if (ioctl(fd, FIONREAD, &bytes_left) != 0) {
return;
}

if (bytes_left == 0) {
return;
}

(void)nanosleep(&sleep_time, NULL);
}
}

static void nhw_upty_cleanup(void) {
for (int i = 0; i < NHW_UARTE_TOTAL_INST; i++) {
struct upty_st_t *u_el = &upty_st[i];

if (u_el->in_fd != -1) {
close(u_el->in_fd);
u_el->in_fd = -1;
}
if (u_el->out_fd != -1) {
if (u_el->wait_for_readers) {
(void)tcdrain(u_el->out_fd);

char *slave_name = ptsname(u_el->out_fd);
if (slave_name != NULL) {
int slave_fd = open(slave_name, O_RDWR | O_NOCTTY);
if (slave_fd != -1) {
nhw_upty_wait_for_fionread_empty(slave_fd);
close(slave_fd);
}
}
}

close(u_el->out_fd);
if (u_el->in_fd == u_el->out_fd) {
u_el->in_fd = -1;
}
u_el->out_fd = -1;
}
if (u_el->in_fd != -1) {
close(u_el->in_fd);
u_el->in_fd = -1;
}
}
}

Expand All @@ -234,15 +275,17 @@ static void parse_poll_period(char *argv, int offset) {
}

static void nhw_upty_backend_register_cmdline(void) {
#define OPT_PER_UART 4
#define OPT_PER_UART 5
static bs_args_struct_t args[OPT_PER_UART*NHW_UARTE_TOTAL_INST + 1 /* End marker */];
static char descr_connect[] = "Connect this UART to a pseudoterminal";
static char descr_auto[] = "Automatically attach to the UART terminal (implies uartx_pty)";
static char descr_cmd[] = "Command used to automatically attach to the terminal (implies "
"uartx_pty_attach), by default: '" DEFAULT_CMD "'";
static char descr_ignoreRTS[] = "Hold feeding data from the PTY if RTS is high (note: "
"If HW flow control is disabled the UART never lowers RTS)";
#define OPTION_LEN (4 + 2 + 15 + 1)
static char descr_wait_readers[] = "At exit, wait for this UART's PTY slave FIONREAD counter "
"to reach 0 before closing";
#define OPTION_LEN (4 + 2 + 21 + 1)
static char options[NHW_UARTE_TOTAL_INST][OPT_PER_UART][OPTION_LEN];
static char opt_cmd[]= "cmd";

Expand All @@ -251,6 +294,7 @@ static void nhw_upty_backend_register_cmdline(void) {
snprintf(options[i][1], OPTION_LEN, "uart%i_pty_attach", i);
snprintf(options[i][2], OPTION_LEN, "uart%i_pty_attach_cmd", i);
snprintf(options[i][3], OPTION_LEN, "uart%i_pty_respect_RTS", i);
snprintf(options[i][4], OPTION_LEN, "uart%i_pty_wait_for_readers", i);

args[OPT_PER_UART*i].option = options[i][0];
args[OPT_PER_UART*i].is_switch = true;
Expand All @@ -275,6 +319,12 @@ static void nhw_upty_backend_register_cmdline(void) {
args[OPT_PER_UART*i + 3].type = 'b';
args[OPT_PER_UART*i + 3].dest = &upty_st[i].respect_RTS;
args[OPT_PER_UART*i + 3].descript = descr_ignoreRTS;

args[OPT_PER_UART*i + 4].option = options[i][4];
args[OPT_PER_UART*i + 4].is_switch = true;
args[OPT_PER_UART*i + 4].type = 'b';
args[OPT_PER_UART*i + 4].dest = &upty_st[i].wait_for_readers;
args[OPT_PER_UART*i + 4].descript = descr_wait_readers;
}

bs_add_extra_dynargs(args);
Expand Down