Re: [PATCH v4 13/13] tools: gpio: implement gpio-watch

[Andy Shevchenko]

On Tue, Dec 24, 2019 at 01:07:09PM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> 
> Add a simple program that allows to test the new LINECHANGED_FD ioctl().

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> ---
>  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@xxxxxxxxxxxx>
> + */
> +
> +#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
> 

-- 
With Best Regards,
Andy Shevchenko