[libgpiod][PATCH] tools: gpiomon: add timeout option

[Gabriel Matni <gabriel.matni@xxxxxxxx>]

From: Gabriel Matni <gabriel.matni@xxxxxxxx>

Add a timeout option which allows gpiomon to gracefully exit upon expiry.
This is handy for scripting as it allows developers to implement an action
when no trigger has been detected for a given period of time.

Signed-off-by: Gabriel Matni <gabriel.matni@xxxxxxxx>
---
diff --git a/tools/gpiomon.c b/tools/gpiomon.c
index cc08f17dd2b4..7ef35fa69b1d 100644
--- a/tools/gpiomon.c
+++ b/tools/gpiomon.c
@@ -30,6 +30,7 @@ struct config {
 	const char *fmt;
 	enum gpiod_line_clock event_clock;
 	int timestamp_fmt;
+	unsigned int timeout;
 };
 
 static void print_help(void)
@@ -68,9 +69,12 @@ static void print_help(void)
 	printf("  -s, --strict\t\tabort if requested line names are not unique\n");
 	printf("      --unquoted\tdon't quote line or consumer names\n");
 	printf("      --utc\t\tformat event timestamps as UTC (default for 'realtime')\n");
+	printf("  -t, --timeout <timeout>\n");
+	printf("\t\t\tpoll timeout, format similar to debounce-period\n");
 	printf("  -v, --version\t\toutput version information and exit\n");
 	print_chip_help();
 	print_period_help();
+	print_timeout_help();
 	printf("\n");
 	printf("Format specifiers:\n");
 	printf("  %%o   GPIO line offset\n");
@@ -109,7 +113,7 @@ static int parse_event_clock_or_die(const char *option)
 
 static int parse_config(int argc, char **argv, struct config *cfg)
 {
-	static const char *const shortopts = "+b:c:C:e:E:hF:ln:p:qshv";
+	static const char *const shortopts = "+b:c:C:e:E:hF:ln:p:qst:hv";
 
 	const struct option longopts[] = {
 		{ "active-low",	no_argument,	NULL,		'l' },
@@ -128,6 +132,7 @@ static int parse_config(int argc, char **argv, struct config *cfg)
 		{ "quiet",	no_argument,	NULL,		'q' },
 		{ "silent",	no_argument,	NULL,		'q' },
 		{ "strict",	no_argument,	NULL,		's' },
+		{ "timeout",	required_argument,	NULL,		't' },
 		{ "unquoted",	no_argument,	NULL,		'Q' },
 		{ "utc",	no_argument,	&cfg->timestamp_fmt,	1 },
 		{ "version",	no_argument,	NULL,		'v' },
@@ -139,6 +144,7 @@ static int parse_config(int argc, char **argv, struct config *cfg)
 	memset(cfg, 0, sizeof(*cfg));
 	cfg->edges = GPIOD_LINE_EDGE_BOTH;
 	cfg->consumer = "gpiomon";
+	cfg->timeout = -1;
 
 	for (;;) {
 		optc = getopt_long(argc, argv, shortopts, longopts, &opti);
@@ -188,6 +194,9 @@ static int parse_config(int argc, char **argv, struct config *cfg)
 		case 's':
 			cfg->strict = true;
 			break;
+		case 't':
+			cfg->timeout = parse_period_or_die(optarg) / 1000;
+			break;
 		case 'h':
 			print_help();
 			exit(EXIT_SUCCESS);
@@ -442,11 +451,16 @@ int main(int argc, char **argv)
 		print_banner(argc, argv);
 
 	for (;;) {
+		int ret;
 		fflush(stdout);
 
-		if (poll(pollfds, resolver->num_chips, -1) < 0)
+		ret = poll(pollfds, resolver->num_chips, cfg.timeout);
+		if (ret < 0)
 			die_perror("error polling for events");
 
+		if (ret == 0)
+			goto done;
+
 		for (i = 0; i < resolver->num_chips; i++) {
 			if (pollfds[i].revents == 0)
 				continue;
diff --git a/tools/tools-common.c b/tools/tools-common.c
index a0080fcdae1f..12c350aa8a48 100644
--- a/tools/tools-common.c
+++ b/tools/tools-common.c
@@ -188,6 +188,13 @@ void print_period_help(void)
 	printf("    Supported units are 's', 'ms', and 'us'.\n");
 }
 
+void print_timeout_help(void)
+{
+	printf("\nTimeout:\n");
+	printf("    Timeout is taken as milliseconds unless a unit is specified. e.g. 1s.\n");
+	printf("    Supported units are 's', 'ms'.\n");
+}
+
 #define TIME_BUFFER_SIZE 20
 
 /*
diff --git a/tools/tools-common.h b/tools/tools-common.h
index 434e5ba5d271..2ee8f51b3c7c 100644
--- a/tools/tools-common.h
+++ b/tools/tools-common.h
@@ -92,6 +92,7 @@ unsigned int parse_uint_or_die(const char *option);
 void print_bias_help(void);
 void print_chip_help(void);
 void print_period_help(void);
+void print_timeout_help(void);
 void print_event_time(uint64_t evtime, int format);
 void print_line_attributes(struct gpiod_line_info *info, bool unquoted_strings);
 void print_line_id(struct line_resolver *resolver, int chip_num,