tools/gpio: add the gpio-event-mon tool

The gpio-event-mon is used from userspace as an example of how
to monitor GPIO line events. It will latch on to a certain
GPIO line on a certain gpiochip and print timestamped events
as they arrive.

Example output:
$ gpio-event-mon -n gpiochip2 -o 0 -r -f
Monitoring line 0 on gpiochip2
Initial line value: 1
GPIO EVENT 946685798487609863: falling edge
GPIO EVENT 946685798732482910: rising edge
GPIO EVENT 946685799115997314: falling edge
GPIO EVENT 946685799381469726: rising edge

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/tools/gpio/Makefile b/tools/gpio/Makefile
index aea2394..619314f 100644 (file)
--- a/tools/gpio/Makefile
+++ b/tools/gpio/Makefile
@@ -1,13 +1,14 @@
 CC = $(CROSS_COMPILE)gcc
 CFLAGS += -O2 -Wall -g -D_GNU_SOURCE
 
-all: lsgpio gpio-hammer
+all: lsgpio gpio-hammer gpio-event-mon
 
 lsgpio: lsgpio.o gpio-utils.o
 gpio-hammer: gpio-hammer.o gpio-utils.o
+gpio-event-mon: gpio-event-mon.o gpio-utils.o
 
 %.o: %.c gpio-utils.h
 
 .PHONY: clean
 clean:
-       rm -f *.o lsgpio gpio-hammer
+       rm -f *.o lsgpio gpio-hammer gpio-event-mon

diff --git a/tools/gpio/gpio-event-mon.c b/tools/gpio/gpio-event-mon.c
new file mode 100644 (file)
index 0000000..448ed96
--- /dev/null
+++ b/tools/gpio/gpio-event-mon.c
@@ -0,0 +1,192 @@
+/*
+ * gpio-hammer - example swiss army knife to shake GPIO lines on a system
+ *
+ * Copyright (C) 2016 Linus Walleij
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * Usage:
+ *     gpio-event-mon -n <device-name> -o <offset>
+ */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <dirent.h>
+#include <errno.h>
+#include <string.h>
+#include <poll.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <inttypes.h>
+#include <sys/ioctl.h>
+#include <linux/gpio.h>
+
+int monitor_device(const char *device_name,
+                  unsigned int line,
+                  u_int32_t handleflags,
+                  u_int32_t eventflags,
+                  unsigned int loops)
+{
+       struct gpioevent_request req;
+       struct gpiohandle_data data;
+       char *chrdev_name;
+       int fd;
+       int ret;
+       int i = 0;
+
+       ret = asprintf(&chrdev_name, "/dev/%s", device_name);
+       if (ret < 0)
+               return -ENOMEM;
+
+       fd = open(chrdev_name, 0);
+       if (fd == -1) {
+               ret = -errno;
+               fprintf(stderr, "Failed to open %s\n", chrdev_name);
+               goto exit_close_error;
+       }
+
+       req.lineoffset = line;
+       req.handleflags = handleflags;
+       req.eventflags = eventflags;
+       strcpy(req.consumer_label, "gpio-event-mon");
+
+       ret = ioctl(fd, GPIO_GET_LINEEVENT_IOCTL, &req);
+       if (ret == -1) {
+               ret = -errno;
+               fprintf(stderr, "Failed to issue GET EVENT "
+                       "IOCTL (%d)\n",
+                       ret);
+               goto exit_close_error;
+       }
+
+       /* Read initial states */
+       ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
+       if (ret == -1) {
+               ret = -errno;
+               fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE "
+                       "VALUES IOCTL (%d)\n",
+                       ret);
+               goto exit_close_error;
+       }
+
+       fprintf(stdout, "Monitoring line %d on %s\n", line, device_name);
+       fprintf(stdout, "Initial line value: %d\n", data.values[0]);
+
+       while (1) {
+               struct gpioevent_data event;
+
+               ret = read(req.fd, &event, sizeof(event));
+               if (ret == -1) {
+                       if (errno == -EAGAIN) {
+                               fprintf(stderr, "nothing available\n");
+                               continue;
+                       } else {
+                               ret = -errno;
+                               fprintf(stderr, "Failed to read event (%d)\n",
+                                       ret);
+                               break;
+                       }
+               }
+
+               if (ret != sizeof(event)) {
+                       fprintf(stderr, "Reading event failed\n");
+                       ret = -EIO;
+                       break;
+               }
+               fprintf(stdout, "GPIO EVENT %" PRIu64 ": ", event.timestamp);
+               switch (event.id) {
+               case GPIOEVENT_EVENT_RISING_EDGE:
+                       fprintf(stdout, "rising edge");
+                       break;
+               case GPIOEVENT_EVENT_FALLING_EDGE:
+                       fprintf(stdout, "falling edge");
+                       break;
+               default:
+                       fprintf(stdout, "unknown event");
+               }
+               fprintf(stdout, "\n");
+
+               i++;
+               if (i == loops)
+                       break;
+       }
+
+exit_close_error:
+       if (close(fd) == -1)
+               perror("Failed to close GPIO character device file");
+       free(chrdev_name);
+       return ret;
+}
+
+void print_usage(void)
+{
+       fprintf(stderr, "Usage: gpio-event-mon [options]...\n"
+               "Listen to events on GPIO lines, 0->1 1->0\n"
+               "  -n <name>  Listen on GPIOs on a named device (must be stated)\n"
+               "  -o <n>     Offset to monitor\n"
+               "  -d         Set line as open drain\n"
+               "  -s         Set line as open source\n"
+               "  -r         Listen for rising edges\n"
+               "  -f         Listen for falling edges\n"
+               " [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"
+               "  -?         This helptext\n"
+               "\n"
+               "Example:\n"
+               "gpio-event-mon -n gpiochip0 -o 4 -r -f\n"
+       );
+}
+
+int main(int argc, char **argv)
+{
+       const char *device_name = NULL;
+       unsigned int line = -1;
+       unsigned int loops = 0;
+       u_int32_t handleflags = GPIOHANDLE_REQUEST_INPUT;
+       u_int32_t eventflags = 0;
+       int c;
+
+       while ((c = getopt(argc, argv, "c:n:o:dsrf?")) != -1) {
+               switch (c) {
+               case 'c':
+                       loops = strtoul(optarg, NULL, 10);
+                       break;
+               case 'n':
+                       device_name = optarg;
+                       break;
+               case 'o':
+                       line = strtoul(optarg, NULL, 10);
+                       break;
+               case 'd':
+                       handleflags |= GPIOHANDLE_REQUEST_OPEN_DRAIN;
+                       break;
+               case 's':
+                       handleflags |= GPIOHANDLE_REQUEST_OPEN_SOURCE;
+                       break;
+               case 'r':
+                       eventflags |= GPIOEVENT_REQUEST_RISING_EDGE;
+                       break;
+               case 'f':
+                       eventflags |= GPIOEVENT_REQUEST_FALLING_EDGE;
+                       break;
+               case '?':
+                       print_usage();
+                       return -1;
+               }
+       }
+
+       if (!device_name || line == -1) {
+               print_usage();
+               return -1;
+       }
+       if (!eventflags) {
+               printf("No flags specified, listening on both rising and "
+                      "falling edges\n");
+               eventflags = GPIOEVENT_REQUEST_BOTH_EDGES;
+       }
+       return monitor_device(device_name, line, handleflags,
+                             eventflags, loops);
+}