Add LED

README.md

@@ -3,7 +3,7 @@ A collection of tools and utility apps for the PINE64 PinePhone.
 
 ## Components
 ### backlight
-Get / Set backlight brightness.
+Get / Set display backlight brightness.
 
 ```
 $ pptk-backlight get
@@ -11,6 +11,19 @@ $ pptk-backlight get
 $ pptk-backlight set 6
 ```
 
+### led
+Get / Set LED light level for the RGB indicator and the white flash light.
+
+```
+# Get red RGB indicator brightness
+$ pptk-led get red
+255
+# Turn RED indicator OFF
+$ pptk-led set red 0
+# Turn FLASH light ON
+$ pptk-led set flash 255
+```
+
 ## Build & Install
 ```
 $ meson build

meson.build

@@ -1,3 +1,5 @@
 project('PinePhone Toolkit', 'c')
 executable('pptk-backlight', ['src/backlight.c'],
   install: true, install_mode: ['rwsr-xr-x', 0, 0])
+executable('pptk-led', ['src/led.c'],
+  install: true, install_mode: ['rwsr-xr-x', 0, 0])

src/led.c

@@ -0,0 +1,96 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static char *argv0 = "./led";
+static char *led_file_template = "/sys/class/leds/%s:%s/brightness";
+
+void print_usage()
+{
+    printf("usage: %s COMMAND COLOR [VALUE]\n", argv0);
+    printf("  COMMAND = {get, set}\n");
+    printf("    get ... prints LED level\n");
+    printf("    set ... sets LED level to VALUE\n");
+    printf("  COLOR = {red, green, blue, flash}\n");
+    printf("    red   ... red:indicator LED\n");
+    printf("    green ... green:indicator LED\n");
+    printf("    blue  ... blue:indicator LED\n");
+    printf("    flash ... white:flash LED\n");
+    printf("  VALUE = [0..255] ... light level\n");
+}
+
+void print_usage_and_fail()
+{
+    print_usage();
+    exit(EXIT_FAILURE);
+}
+
+void command_get(char *filepath)
+{
+    FILE *fp = fopen(filepath, "r");
+    if (fp == NULL) {
+        fprintf(stderr, "Cannot open file '%s' for reading.\n", filepath);
+        exit(EXIT_FAILURE);
+    }
+    int buffer_length = 255;
+    char buffer[buffer_length];
+    while (fgets(buffer, buffer_length, fp)) {
+        printf("%s", buffer);
+    }
+    fclose(fp);
+}
+
+void command_set(char *filepath, int value)
+{
+    if (setuid(0)) {
+        fprintf(stderr, "Cannot set root permissions via setuid(0).\n");
+        exit(EXIT_FAILURE);
+    }
+
+    FILE *fp = fopen(filepath, "w+");
+    if (fp == NULL) {
+        fprintf(stderr, "Cannot open file '%s' for writing.\n", filepath);
+        exit(EXIT_FAILURE);
+    }
+    fprintf(fp, "%d\n", value);
+    fclose(fp);
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc < 1) {
+        print_usage_and_fail();
+    }
+    argv0 = argv[0];
+    if (argc < 3) {
+        print_usage_and_fail();
+    }
+    char *command = argv[1];
+    char *led = argv[2];
+    if (strcmp(led, "red") != 0
+        && strcmp(led, "blue") != 0
+        && strcmp(led, "green") != 0
+        && strcmp(led, "flash")) {
+        print_usage_and_fail();
+    }
+    char *type = "indicator";
+    if (strcmp(led, "flash") == 0) {
+        led = "white";
+        type = "flash";
+    }
+    char filename[255];
+    sprintf(filename, led_file_template, led, type);
+    if ((strcmp(command, "get") == 0) && (argc == 3)) {
+        command_get(filename);
+    } else if ((strcmp(command, "set") == 0) && (argc == 4)) {
+        int value = atoi(argv[3]);
+        if (value < 0 || value > 255) {
+            print_usage_and_fail();
+        }
+        command_set(filename, value);
+    } else {
+        print_usage_and_fail();
+    }
+    exit(EXIT_SUCCESS);
+}