From: Nikita Shubin <nikita.shubin@maquefel.me>
Date: Thu, 6 Mar 2025 11:41:15 +0000 (+0300)
Subject: add gpio-watch to monitor config events
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;p=tools%2Fqemu-gpio-tools.git

add gpio-watch to monitor config events

Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
---

diff --git a/Makefile b/Makefile
index 23c552e..614301e 100644
--- a/Makefile
+++ b/Makefile
@@ -16,7 +16,8 @@ INCLUDE += -Isrc/
 all: \
 	lsgpio \
 	gpio-event-mon \
-	gpio-hammer
+	gpio-hammer \
+	gpio-watch
 
 .PHONY: debug
 debug: CFLAGS+= -O0 -DDEBUG -ggdb -g3 -Wno-unused-variable
@@ -56,6 +57,12 @@ gpio-hammer: gpio-hammer.o gpio-utils.o
 gpio-hammer.o: src/gpio-hammer.c
 	$(CC) $(CFLAGS) -c src/gpio-hammer.c $(INCLUDE)
 
+gpio-watch: gpio-watch.o gpio-utils.o
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+
+gpio-watch.o: src/gpio-watch.c
+	$(CC) $(CFLAGS) -c src/gpio-watch.c $(INCLUDE)
+
 gpio-utils.o: src/gpio-utils.c
 	$(CC) $(CFLAGS) -c src/gpio-utils.c $(INCLUDE)
 
diff --git a/src/gpio-watch.c b/src/gpio-watch.c
new file mode 100644
index 0000000..0945040
--- /dev/null
+++ b/src/gpio-watch.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * gpio-watch - monitor unrequested lines for property changes using the
+ *              character device
+ *
+ * Copyright (C) 2019 BayLibre SAS
+ * Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
+ */
+
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <linux/gpio.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+int main(int argc, char **argv)
+{
+	unsigned long val = GPIO_V2_GET_LINEINFO_WATCH_IOCTL;
+	struct gpio_v2_line_info_changed chg;
+	struct gpio_v2_line_info req;
+	struct sockaddr_un addr;
+	struct pollfd pfd;
+	int fd, i, j, ret;
+	char *event, *end;
+	ssize_t rd;
+
+	if (argc < 3)
+		goto err_usage;
+
+	fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	memset(&addr, 0, sizeof(addr));
+
+	addr.sun_family = AF_UNIX;
+    strncpy(addr.sun_path, argv[1], sizeof(addr.sun_path) - 1);
+
+	ret = connect(fd, (const struct sockaddr *) &addr, sizeof(addr));
+	if (ret == -1) {
+		perror("unable to open gpiochip");
+		return EXIT_FAILURE;
+	}
+
+	for (i = 0, j = 2; i < argc - 2; i++, j++) {
+		memset(&req, 0, sizeof(req));
+
+		req.offset = strtoul(argv[j], &end, 0);
+		if (*end != '\0')
+			goto err_usage;
+
+		ret = write(fd, &val, sizeof(val));
+		if (ret <= 0) {
+			perror("unable to write ioctl() magick");
+			return EXIT_FAILURE;
+		}
+
+		ret = write(fd, &req, sizeof(req));
+		if (ret <= 0) {
+			perror("unable to write line watch request");
+			return EXIT_FAILURE;
+		}
+
+		ret = recv(fd, &req, sizeof(req), MSG_WAITALL);
+		if (ret != sizeof(req)) {
+			perror("unable to read line watch response");
+			return EXIT_FAILURE;
+		}
+	}
+
+	pfd.fd = fd;
+	pfd.events = POLLIN | POLLPRI;
+
+	for (;;) {
+		ret = poll(&pfd, 1, 5000);
+		if (ret < 0) {
+			perror("error polling the linechanged fd");
+			return EXIT_FAILURE;
+		} else if (ret > 0) {
+			memset(&chg, 0, sizeof(chg));
+			rd = read(pfd.fd, &chg, sizeof(chg));
+			if (rd < 0 || rd != sizeof(chg)) {
+				if (rd != sizeof(chg))
+					errno = EIO;
+
+				perror("error reading line change event");
+				return EXIT_FAILURE;
+			}
+
+			switch (chg.event_type) {
+			case GPIO_V2_LINE_CHANGED_REQUESTED:
+				event = "requested";
+				break;
+			case GPIO_V2_LINE_CHANGED_RELEASED:
+				event = "released";
+				break;
+			case GPIO_V2_LINE_CHANGED_CONFIG:
+				event = "config changed";
+				break;
+			default:
+				fprintf(stderr,
+					"invalid event type received from the kernel\n");
+				return EXIT_FAILURE;
+			}
+
+			printf("line %u: %s at %" PRIu64 "\n",
+			       chg.info.offset, event, (uint64_t)chg.timestamp_ns);
+		}
+	}
+
+	return 0;
+
+err_usage:
+	printf("%s: <gpiochip> <line0> <line1> ...\n", argv[0]);
+	return EXIT_FAILURE;
+}