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tools: gpio: implement gpio-watch

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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>
This commit is contained in:
Bartosz Golaszewski 2019-11-27 10:17:54 +01:00
parent 51c1064e82
commit 33f0c47b8f
4 changed files with 111 additions and 1 deletions
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1
tools/gpio/.gitignore vendored
View File

@ -1,4 +1,5 @@
gpio-event-mon
gpio-hammer
gpio-watch
lsgpio
include/linux/gpio.h

1
tools/gpio/Build
View File

@ -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

11
tools/gpio/Makefile
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@ -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

99
tools/gpio/gpio-watch.c Normal file
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@ -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;
}