[PATCH] tools/leds: Add led_hw_brightness_mon program

[PATCH] tools/leds: Add led_hw_brightness_mon program

[Jacek Anaszewski]

LED subsystem supports POLLPRI on "brightness_hw_changed" sysfs file
of LED class devices. This tool demonstrates how to use the feature.

Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Pavel Machek <pavel@ucw.cz>
---
 tools/leds/Makefile                |  4 +-
 tools/leds/led_hw_brightness_mon.c | 84 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 2 deletions(-)
 create mode 100644 tools/leds/led_hw_brightness_mon.c

diff --git a/tools/leds/Makefile b/tools/leds/Makefile
index c03a79e..078b666 100644
--- a/tools/leds/Makefile
+++ b/tools/leds/Makefile
@@ -3,11 +3,11 @@
 CC = $(CROSS_COMPILE)gcc
 CFLAGS = -Wall -Wextra -g -I../../include/uapi
 
-all: uledmon
+all: uledmon led_hw_brightness_mon
 %: %.c
 	$(CC) $(CFLAGS) -o $@ $^
 
 clean:
-	$(RM) uledmon
+	$(RM) uledmon led_hw_brightness_mon
 
 .PHONY: all clean
diff --git a/tools/leds/led_hw_brightness_mon.c b/tools/leds/led_hw_brightness_mon.c
new file mode 100644
index 0000000..1a97064
--- /dev/null
+++ b/tools/leds/led_hw_brightness_mon.c
@@ -0,0 +1,84 @@
+/*
+ * led_hw_brightness_mon.c
+ *
+ * This program monitors LED brightness level changes having its origin
+ * in hardware/firmware, i.e. outside of kernel control.
+ * A timestamp and brightness value is printed each time the brightness changes.
+ *
+ * Usage: led_notify_mon <device-name>
+ *
+ * <device-name> is the name of the LED class device to be monitored. Pressing
+ * CTRL+C will exit.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <linux/uleds.h>
+
+int main(int argc, char const *argv[])
+{
+	int fd, ret;
+	char brightness_file_path[LED_MAX_NAME_SIZE + 11];
+	struct pollfd pollfd;
+	struct timespec ts;
+	char buf[11];
+
+	if (argc != 2) {
+		fprintf(stderr, "Requires <device-name> argument\n");
+		return 1;
+	}
+
+	snprintf(brightness_file_path, LED_MAX_NAME_SIZE,
+		 "/sys/class/leds/%s/brightness_hw_changed", argv[1]);
+
+	fd = open(brightness_file_path, O_RDONLY);
+	if (fd == -1) {
+		printf("Failed to open %s file\n", brightness_file_path);
+		return 1;
+	}
+
+	/*
+	 * read may fail if no hw brightness change has occurred so far,
+	 * but it is required to avoid spurious poll notifications in
+	 * the opposite case.
+	 */
+	read(fd, buf, sizeof(buf));
+
+	pollfd.fd = fd;
+	pollfd.events = POLLPRI;
+
+	while (1) {
+		ret = poll(&pollfd, 1, -1);
+		if (ret == -1) {
+			printf("Failed to poll %s file (%d)\n",
+				brightness_file_path, ret);
+			ret = 1;
+			break;
+		}
+
+		clock_gettime(CLOCK_MONOTONIC, &ts);
+
+		ret = read(fd, buf, sizeof(buf));
+		if (ret < 0)
+			break;
+
+		ret = lseek(pollfd.fd, 0, SEEK_SET);
+		if (ret < 0) {
+			printf("lseek failed (%d)\n", ret);
+			break;
+		}
+
+		printf("[%ld.%09ld] %d\n", ts.tv_sec, ts.tv_nsec, atoi(buf));
+	}
+
+	close(fd);
+
+	return ret;
+}
-- 
2.1.4

Re: [PATCH] tools/leds: Add led_hw_brightness_mon program

[Hans de Goede]

Hi,

On 01/29/2017 12:52 PM, Jacek Anaszewski wrote:
> LED subsystem supports POLLPRI on "brightness_hw_changed" sysfs file
> of LED class devices. This tool demonstrates how to use the feature.
>
> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Pavel Machek <pavel@ucw.cz>

Looks good to me:

Acked-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans



> ---
>  tools/leds/Makefile                |  4 +-
>  tools/leds/led_hw_brightness_mon.c | 84 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 86 insertions(+), 2 deletions(-)
>  create mode 100644 tools/leds/led_hw_brightness_mon.c
>
> diff --git a/tools/leds/Makefile b/tools/leds/Makefile
> index c03a79e..078b666 100644
> --- a/tools/leds/Makefile
> +++ b/tools/leds/Makefile
> @@ -3,11 +3,11 @@
>  CC = $(CROSS_COMPILE)gcc
>  CFLAGS = -Wall -Wextra -g -I../../include/uapi
>
> -all: uledmon
> +all: uledmon led_hw_brightness_mon
>  %: %.c
>  	$(CC) $(CFLAGS) -o $@ $^
>
>  clean:
> -	$(RM) uledmon
> +	$(RM) uledmon led_hw_brightness_mon
>
>  .PHONY: all clean
> diff --git a/tools/leds/led_hw_brightness_mon.c b/tools/leds/led_hw_brightness_mon.c
> new file mode 100644
> index 0000000..1a97064
> --- /dev/null
> +++ b/tools/leds/led_hw_brightness_mon.c
> @@ -0,0 +1,84 @@
> +/*
> + * led_hw_brightness_mon.c
> + *
> + * This program monitors LED brightness level changes having its origin
> + * in hardware/firmware, i.e. outside of kernel control.
> + * A timestamp and brightness value is printed each time the brightness changes.
> + *
> + * Usage: led_notify_mon <device-name>
> + *
> + * <device-name> is the name of the LED class device to be monitored. Pressing
> + * CTRL+C will exit.
> + */
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <poll.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <time.h>
> +#include <unistd.h>
> +
> +#include <linux/uleds.h>
> +
> +int main(int argc, char const *argv[])
> +{
> +	int fd, ret;
> +	char brightness_file_path[LED_MAX_NAME_SIZE + 11];
> +	struct pollfd pollfd;
> +	struct timespec ts;
> +	char buf[11];
> +
> +	if (argc != 2) {
> +		fprintf(stderr, "Requires <device-name> argument\n");
> +		return 1;
> +	}
> +
> +	snprintf(brightness_file_path, LED_MAX_NAME_SIZE,
> +		 "/sys/class/leds/%s/brightness_hw_changed", argv[1]);
> +
> +	fd = open(brightness_file_path, O_RDONLY);
> +	if (fd == -1) {
> +		printf("Failed to open %s file\n", brightness_file_path);
> +		return 1;
> +	}
> +
> +	/*
> +	 * read may fail if no hw brightness change has occurred so far,
> +	 * but it is required to avoid spurious poll notifications in
> +	 * the opposite case.
> +	 */
> +	read(fd, buf, sizeof(buf));
> +
> +	pollfd.fd = fd;
> +	pollfd.events = POLLPRI;
> +
> +	while (1) {
> +		ret = poll(&pollfd, 1, -1);
> +		if (ret == -1) {
> +			printf("Failed to poll %s file (%d)\n",
> +				brightness_file_path, ret);
> +			ret = 1;
> +			break;
> +		}
> +
> +		clock_gettime(CLOCK_MONOTONIC, &ts);
> +
> +		ret = read(fd, buf, sizeof(buf));
> +		if (ret < 0)
> +			break;
> +
> +		ret = lseek(pollfd.fd, 0, SEEK_SET);
> +		if (ret < 0) {
> +			printf("lseek failed (%d)\n", ret);
> +			break;
> +		}
> +
> +		printf("[%ld.%09ld] %d\n", ts.tv_sec, ts.tv_nsec, atoi(buf));
> +	}
> +
> +	close(fd);
> +
> +	return ret;
> +}
>

Re: [PATCH] tools/leds: Add led_hw_brightness_mon program

[Pavel Machek]

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On Sun 2017-01-29 12:52:31, Jacek Anaszewski wrote:
> LED subsystem supports POLLPRI on "brightness_hw_changed" sysfs file
> of LED class devices. This tool demonstrates how to use the feature.
> 
> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
> Cc: Hans de Goede <hdegoede@redhat.com>

I'd name it something shorter. We have "uledmon" so
"led_hw_brightness_mon" is little out of place.

Acked-by: Pavel Machek <pavel@ucw.cz>

							Pavel
							
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH] tools/leds: Add led_hw_brightness_mon program

[Jacek Anaszewski]

On 01/29/2017 05:56 PM, Pavel Machek wrote:
> On Sun 2017-01-29 12:52:31, Jacek Anaszewski wrote:
>> LED subsystem supports POLLPRI on "brightness_hw_changed" sysfs file
>> of LED class devices. This tool demonstrates how to use the feature.
>>
>> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
>> Cc: Hans de Goede <hdegoede@redhat.com>
> 
> I'd name it something shorter. We have "uledmon" so
> "led_hw_brightness_mon" is little out of place.
> 
> Acked-by: Pavel Machek <pavel@ucw.cz>

I had the same doubts, but didn't finally manage to devise
something more concise. Feel free to propose better name.
For now I'm applying the patch as is. Thanks.

-- 
Best regards,
Jacek Anaszewski