LED driver for Linux /sys/class/leds (#14981)

New driver for controlling system LEDs offered via /sys/class/leds.
Currently it handles led0, led1 etc. type of entries, which are
present on e.g. Raspberry Pi's.

Makefile.common

@@ -2416,7 +2416,8 @@ ifeq ($(HAVE_STATIC_AUDIO_FILTERS), 1)
 endif
 
 ifeq ($(HAVE_RPILED), 1)
-   OBJ += led/drivers/led_rpi.o
+   OBJ += led/drivers/led_rpi.o \
+          led/drivers/led_sys_linux.o
 endif
 
 ifneq ($(findstring Win32,$(OS)),)

griffin/griffin.c

@@ -904,6 +904,7 @@ LEDS
 
 #if defined(HAVE_RPILED)
 #include "../led/drivers/led_rpi.c"
+#include "../led/drivers/led_sys_linux.c"
 #endif
 
 #if defined(_WIN32) && !defined(_XBOX) && !defined(__WINRT__)

led/drivers/led_sys_linux.c

@@ -0,0 +1,114 @@
+/*  RetroArch - A frontend for libretro.
+ *
+ *  RetroArch is free software: you can redistribute it and/or modify it under the terms
+ *  of the GNU General Public License as published by the Free Software Found-
+ *  ation, either version 3 of the License, or (at your option) any later version.
+ *
+ *  RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ *  PURPOSE.  See the GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with RetroArch.
+ *  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <compat/strl.h>
+
+#include "../led_driver.h"
+#include "../led_defines.h"
+
+#include "../../configuration.h"
+
+typedef struct
+{
+   int setup[MAX_LEDS];
+   int map[MAX_LEDS];
+} sysled_t;
+
+/* TODO/FIXME - static globals */
+static sysled_t sys_curins;
+static sysled_t *sys_cur = &sys_curins;
+
+static void sys_led_init(void)
+{
+   int i;
+   settings_t *settings = config_get_ptr();
+
+   if (!settings)
+      return;
+
+   for (i = 0; i < MAX_LEDS; i++)
+   {
+      sys_cur->setup[i] = 0;
+      sys_cur->map[i]   = settings->uints.led_map[i];
+   }
+}
+
+static void sys_led_free(void)
+{
+   int i;
+
+   for (i = 0; i < MAX_LEDS; i++)
+   {
+      sys_cur->setup[i] = 0;
+      sys_cur->map[i]   = 0;
+   }
+}
+
+static int set_sysled(int sysled, int value)
+{
+   FILE *fp;
+   char buf[256];
+   snprintf(buf, sizeof(buf), "/sys/class/leds/led%d/brightness", sysled);
+
+   /* Failed to set LED? */
+   if (!(fp = fopen(buf, "w")))
+      return -1;
+
+   /* Simplified: max_brightness could be taken into account */
+   /* Pi Zero may have reversed brightness? */
+   fprintf(fp, "%d\n", value ? 1 : 0);
+   fclose(fp);
+   return 1;
+}
+
+static int setup_sysled(int sysled)
+{
+   FILE *fp;
+   char buf[256];
+   snprintf(buf, sizeof(buf), "/sys/class/leds/led%d/trigger", sysled);
+   
+   if (!(fp = fopen(buf, "w")))
+      return -1;
+
+   /* TODO: read actual trigger in [] and restore on exit */
+   fprintf(fp, "none");
+   fclose(fp);
+   return 1;
+}
+
+static void sys_led_set(int led, int state)
+{
+   int sysled = 0;
+
+   /* Invalid LED? */
+   if((led < 0) || (led >= MAX_LEDS))
+      return;
+
+   sysled = sys_cur->map[led];
+   if(sysled < 0)
+      return;
+
+   if(sys_cur->setup[led] == 0)
+      sys_cur->setup[led] = setup_sysled(sysled);
+   if(sys_cur->setup[led] > 0)
+      set_sysled(sysled, state);
+}
+
+const led_driver_t sys_led_driver = {
+   sys_led_init,
+   sys_led_free,
+   sys_led_set,
+   "sysled"
+};

led/led_driver.c

@@ -47,6 +47,8 @@ void led_driver_init(const char *led_driver)
 #ifdef HAVE_RPILED
    if (string_is_equal("rpi", drivername))
       current_led_driver  = &rpi_led_driver;
+   if (string_is_equal("sysled", drivername))
+      current_led_driver  = &sys_led_driver;
 #endif
 
 #if (defined(_WIN32) && !defined(_XBOX) && !defined(__WINRT__)) || defined(HAVE_X11)
@@ -54,6 +56,7 @@ void led_driver_init(const char *led_driver)
       current_led_driver  = &keyboard_led_driver;
 #endif
 
+
    if (current_led_driver)
       (*current_led_driver->init)();
 

led/led_driver.h

@@ -44,6 +44,7 @@ void led_driver_set_led(int led, int value);
 extern const led_driver_t overlay_led_driver;
 extern const led_driver_t rpi_led_driver;
 extern const led_driver_t keyboard_led_driver;
+extern const led_driver_t sys_led_driver;
 
 RETRO_END_DECLS