Re: [PATCH v2 11/11] tools: gpio: implement gpio-watch

From: Bartosz Golaszewski
Date: Thu Dec 05 2019 - 04:48:55 EST

czw., 5 gru 2019 o 10:44 Kent Gibson <warthog618@xxxxxxxxx> napisaÅ(a):
>
> On Wed, Dec 04, 2019 at 04:59:41PM +0100, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> >
> > Add a simple program that allows to test the new LINECHANGED_FD ioctl().
> >
>
> A minor nit - the ioctl has since been changed to LINEINFO_WATCH.

Will fix, thanks.

>
> Do you have anything else to test the ioctls?
> Either way, I'll try to find some time to add some to my gpiod library.
>

The time I can spend on this is limited, so I decided to go with the
kernel API first with a simple user-space test in the kernel source.
Once we agree upon it, I'll add support for this to libgpiod. The
user-space part would then probably be merged after v5.6-rc1 is tagged
and it leaves us 7 weeks to fix any bugs.

This is what I plan on doing with your series too. I hope to merge it
next week and then we can fix any potential bugs and do a libgpiod
release simultaneous with linux v5.5.

Bart

> Kent.
>
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> > ---
> > tools/gpio/.gitignore | 1 +
> > tools/gpio/Build | 1 +
> > tools/gpio/Makefile | 11 +++-
> > tools/gpio/gpio-watch.c | 112 ++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 124 insertions(+), 1 deletion(-)
> > create mode 100644 tools/gpio/gpio-watch.c
> >
> > diff --git a/tools/gpio/.gitignore b/tools/gpio/.gitignore
> > index a94c0e83b209..fffd32969d62 100644
> > --- a/tools/gpio/.gitignore
> > +++ b/tools/gpio/.gitignore
> > @@ -1,4 +1,5 @@
> > gpio-event-mon
> > gpio-hammer
> > lsgpio
> > +gpio-watch
> > 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..69aee43655ae
> > --- /dev/null
> > +++ b/tools/gpio/gpio-watch.c
> > @@ -0,0 +1,112 @@
> > +// 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>
> > +
> > +static bool isnumber(const char *str)
> > +{
> > + size_t sz = strlen(str);
> > + int i;
> > +
> > + for (i = 0; i < sz; i++) {
> > + if (!isdigit(str[i]))
> > + return false;
> > + }
> > +
> > + return true;
> > +}
> > +
> > +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;
> > + 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++) {
> > + if (!isnumber(argv[j]))
> > + goto err_usage;
> > +
> > + memset(&req, 0, sizeof(req));
> > + req.line_offset = atoi(argv[j]);
> > +
> > + 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
> >