tools/leds: Add uledmon program for monitoring userspace LEDs

The uleds driver provides userspace LED devices. This tool is used to
create one of these devices and monitor the changes in brighness for
testing purposes.
Signed-off-by: NDavid Lechner <david@lechnology.com>
Signed-off-by: NJacek Anaszewski <j.anaszewski@samsung.com>

tools/Makefile

@@ -17,6 +17,7 @@ help:
 	@echo '  hv                     - tools used when in Hyper-V clients'
 	@echo '  iio                    - IIO tools'
 	@echo '  kvm_stat               - top-like utility for displaying kvm statistics'
+	@echo '  leds                   - LEDs  tools'
 	@echo '  lguest                 - a minimal 32-bit x86 hypervisor'
 	@echo '  net                    - misc networking tools'
 	@echo '  perf                   - Linux performance measurement and analysis tool'
@@ -56,7 +57,7 @@ acpi: FORCE
 cpupower: FORCE
 	$(call descend,power/$@)
 
-cgroup firewire hv guest spi usb virtio vm net iio gpio objtool: FORCE
+cgroup firewire hv guest spi usb virtio vm net iio gpio objtool leds: FORCE
 	$(call descend,$@)
 
 liblockdep: FORCE
@@ -126,7 +127,7 @@ acpi_clean:
 cpupower_clean:
 	$(call descend,power/cpupower,clean)
 
-cgroup_clean hv_clean firewire_clean lguest_clean spi_clean usb_clean virtio_clean vm_clean net_clean iio_clean gpio_clean objtool_clean:
+cgroup_clean hv_clean firewire_clean lguest_clean spi_clean usb_clean virtio_clean vm_clean net_clean iio_clean gpio_clean objtool_clean leds_clean:
 	$(call descend,$(@:_clean=),clean)
 
 liblockdep_clean:
@@ -164,6 +165,6 @@ clean: acpi_clean cgroup_clean cpupower_clean hv_clean firewire_clean lguest_cle
 		perf_clean selftests_clean turbostat_clean spi_clean usb_clean virtio_clean \
 		vm_clean net_clean iio_clean x86_energy_perf_policy_clean tmon_clean \
 		freefall_clean build_clean libbpf_clean libsubcmd_clean liblockdep_clean \
-		gpio_clean objtool_clean
+		gpio_clean objtool_clean leds_clean
 
 .PHONY: FORCE

tools/leds/.gitignore

+uledmon

tools/leds/Makefile

+# Makefile for LEDs tools
+
+CC = $(CROSS_COMPILE)gcc
+CFLAGS = -Wall -Wextra -g -I../../include/uapi
+
+all: uledmon
+%: %.c
+	$(CC) $(CFLAGS) -o $@ $^
+
+clean:
+	$(RM) uledmon
+
+.PHONY: all clean

tools/leds/uledmon.c

+/*
+ * uledmon.c
+ *
+ * This program creates a new userspace LED class device and monitors it. A
+ * timestamp and brightness value is printed each time the brightness changes.
+ *
+ * Usage: uledmon <device-name>
+ *
+ * <device-name> is the name of the LED class device to be created. Pressing
+ * CTRL+C will exit.
+ */
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <linux/uleds.h>
+
+int main(int argc, char const *argv[])
+{
+	struct uleds_user_dev uleds_dev;
+	int fd, ret;
+	int brightness;
+	struct timespec ts;
+
+	if (argc != 2) {
+		fprintf(stderr, "Requires <device-name> argument\n");
+		return 1;
+	}
+
+	strncpy(uleds_dev.name, argv[1], LED_MAX_NAME_SIZE);
+	uleds_dev.max_brightness = 100;
+
+	fd = open("/dev/uleds", O_RDWR);
+	if (fd == -1) {
+		perror("Failed to open /dev/uleds");
+		return 1;
+	}
+
+	ret = write(fd, &uleds_dev, sizeof(uleds_dev));
+	if (ret == -1) {
+		perror("Failed to write to /dev/uleds");
+		close(fd);
+		return 1;
+	}
+
+	while (1) {
+		ret = read(fd, &brightness, sizeof(brightness));
+		if (ret == -1) {
+			perror("Failed to read from /dev/uleds");
+			close(fd);
+			return 1;
+		}
+		clock_gettime(CLOCK_MONOTONIC, &ts);
+		printf("[%ld.%09ld] %u\n", ts.tv_sec, ts.tv_nsec, brightness);
+	}
+
+	close(fd);
+
+	return 0;
+}