tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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>
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tools/gpio/.gitignore
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tools/gpio/.gitignore
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tools/gpio/Build
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tools/gpio/Build
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tools/gpio/Makefile
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tools/gpio/Makefile
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override CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include
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ALL_TARGETS := lsgpio gpio-hammer gpio-event-mon
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ALL_TARGETS := lsgpio gpio-hammer gpio-event-mon gpio-watch
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ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))
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all: $(ALL_PROGRAMS)
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$(GPIO_EVENT_MON_IN): prepare FORCE $(OUTPUT)gpio-utils-in.o
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$(Q)$(MAKE) $(build)=gpio-event-mon
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$(OUTPUT)gpio-event-mon: $(GPIO_EVENT_MON_IN)
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$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
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#
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# gpio-watch
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#
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GPIO_WATCH_IN := $(OUTPUT)gpio-watch-in.o
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$(GPIO_WATCH_IN): prepare FORCE
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$(Q)$(MAKE) $(build)=gpio-watch
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$(OUTPUT)gpio-watch: $(GPIO_WATCH_IN)
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$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
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clean:
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tools/gpio/gpio-watch.c
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tools/gpio/gpio-watch.c
···
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* gpio-watch - monitor unrequested lines for property changes using the
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* character device
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*
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* Copyright (C) 2019 BayLibre SAS
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* Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
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*/
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#include <ctype.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <linux/gpio.h>
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#include <poll.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <unistd.h>
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int main(int argc, char **argv)
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{
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struct gpioline_info_changed chg;
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struct gpioline_info req;
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struct pollfd pfd;
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int fd, i, j, ret;
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char *event, *end;
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ssize_t rd;
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if (argc < 3)
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goto err_usage;
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fd = open(argv[1], O_RDWR | O_CLOEXEC);
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if (fd < 0) {
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perror("unable to open gpiochip");
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return EXIT_FAILURE;
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}
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for (i = 0, j = 2; i < argc - 2; i++, j++) {
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memset(&req, 0, sizeof(req));
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req.line_offset = strtoul(argv[j], &end, 0);
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if (*end != '\0')
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goto err_usage;
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ret = ioctl(fd, GPIO_GET_LINEINFO_WATCH_IOCTL, &req);
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if (ret) {
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perror("unable to set up line watch");
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return EXIT_FAILURE;
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}
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}
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pfd.fd = fd;
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pfd.events = POLLIN | POLLPRI;
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for (;;) {
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ret = poll(&pfd, 1, 5000);
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if (ret < 0) {
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perror("error polling the linechanged fd");
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return EXIT_FAILURE;
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} else if (ret > 0) {
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memset(&chg, 0, sizeof(chg));
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rd = read(pfd.fd, &chg, sizeof(chg));
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if (rd < 0 || rd != sizeof(chg)) {
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if (rd != sizeof(chg))
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errno = EIO;
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perror("error reading line change event");
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return EXIT_FAILURE;
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}
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switch (chg.event_type) {
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case GPIOLINE_CHANGED_REQUESTED:
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event = "requested";
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break;
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case GPIOLINE_CHANGED_RELEASED:
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event = "released";
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break;
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case GPIOLINE_CHANGED_CONFIG:
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event = "config changed";
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break;
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default:
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fprintf(stderr,
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"invalid event type received from the kernel\n");
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return EXIT_FAILURE;
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}
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printf("line %u: %s at %llu\n",
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chg.info.line_offset, event, chg.timestamp);
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}
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}
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return 0;
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err_usage:
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printf("%s: <gpiochip> <line0> <line1> ...\n", argv[0]);
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return EXIT_FAILURE;
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}