tools: gpio: implement gpio-watch

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>

diff --git a/tools/gpio/.gitignore b/tools/gpio/.gitignore
index a94c0e8..eab36c6 100644 (file)
--- 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 4141f35..67c7b7f 100644 (file)
--- 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 6080de5..842287e 100644 (file)
--- 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 (file)
index 0000000..5cea24f
--- /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;
+}