[PATCH v6 7/7] tools: gpio: implement gpio-watch

Bartosz Golaszewski
2020-01-24T17:27:35Z

Add a simple program that allows to test the new LINECHANGED_FD ioctl().

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
tools/gpio/.gitignore | 1 +
tools/gpio/Build | 1 +
tools/gpio/Makefile | 11 ++++-
tools/gpio/gpio-watch.c | 99 +++++++++++++++++++++++++++++++++++++++++
4 files changed, 111 insertions(+), 1 deletion(-)
create mode 100644 tools/gpio/gpio-watch.c

diff --git a/tools/gpio/.gitignore b/tools/gpio/.gitignore
index a94c0e83b209..eab36c6d7751 100644
--- a/tools/gpio/.gitignore
+++ b/tools/gpio/.gitignore
@@ -1,4 +1,5 @@
gpio-event-mon
gpio-hammer
+gpio-watch
lsgpio
include/linux/gpio.h
diff --git a/tools/gpio/Build b/tools/gpio/Build
index 4141f35837db..67c7b7f6a717 100644
--- a/tools/gpio/Build
+++ b/tools/gpio/Build
@@ -2,3 +2,4 @@ gpio-utils-y += gpio-utils.o
lsgpio-y += lsgpio.o gpio-utils.o
gpio-hammer-y += gpio-hammer.o gpio-utils.o
gpio-event-mon-y += gpio-event-mon.o gpio-utils.o
+gpio-watch-y += gpio-watch.o
diff --git a/tools/gpio/Makefile b/tools/gpio/Makefile
index 6080de58861f..842287e42c83 100644
--- a/tools/gpio/Makefile
+++ b/tools/gpio/Makefile
@@ -18,7 +18,7 @@ MAKEFLAGS += -r

override CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include

-ALL_TARGETS := lsgpio gpio-hammer gpio-event-mon
+ALL_TARGETS := lsgpio gpio-hammer gpio-event-mon gpio-watch
ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))

all: $(ALL_PROGRAMS)
@@ -66,6 +66,15 @@ $(GPIO_EVENT_MON_IN): prepare FORCE $(OUTPUT)gpio-utils-in.o
$(OUTPUT)gpio-event-mon: $(GPIO_EVENT_MON_IN)
$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@

+#
+# gpio-watch
+#
+GPIO_WATCH_IN := $(OUTPUT)gpio-watch-in.o
+$(GPIO_WATCH_IN): prepare FORCE
+ $(Q)$(MAKE) $(build)=gpio-watch
+$(OUTPUT)gpio-watch: $(GPIO_WATCH_IN)
+ $(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
+
clean:
rm -f $(ALL_PROGRAMS)
rm -f $(OUTPUT)include/linux/gpio.h
diff --git a/tools/gpio/gpio-watch.c b/tools/gpio/gpio-watch.c
new file mode 100644
index 000000000000..5cea24fddfa7
--- /dev/null
+++ b/tools/gpio/gpio-watch.c
@@ -0,0 +1,99 @@
+// 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 <linux/gpio.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+int main(int argc, char **argv)
+{
+ struct gpioline_info_changed chg;
+ struct gpioline_info req;
+ struct pollfd pfd;
+ int fd, i, j, ret;
+ char *event, *end;
+ ssize_t rd;
+
+ if (argc < 3)
+ goto err_usage;
+
+ fd = open(argv[1], O_RDWR | O_CLOEXEC);
+ if (fd < 0) {
+ perror("unable to open gpiochip");
+ return EXIT_FAILURE;
+ }
+
+ for (i = 0, j = 2; i < argc - 2; i++, j++) {
+ memset(&req, 0, sizeof(req));
+
+ req.line_offset = strtoul(argv[j], &end, 0);
+ if (*end != '\0')
+ goto err_usage;
+
+ ret = ioctl(fd, GPIO_GET_LINEINFO_WATCH_IOCTL, &req);
+ if (ret) {
+ perror("unable to set up line watch");
+ 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 GPIOLINE_CHANGED_REQUESTED:
+ event = "requested";
+ break;
+ case GPIOLINE_CHANGED_RELEASED:
+ event = "released";
+ break;
+ case GPIOLINE_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 %llu\n",
+ chg.info.line_offset, event, chg.timestamp);
+ }
+ }
+
+ return 0;
+
+err_usage:
+ printf("%s: <gpiochip> <line0> <line1> ...\n", argv[0]);
+ return EXIT_FAILURE;
+}
--
2.23.0