Toggle keyboard backlight using OpenRGB on Lenovo Legion 7

idlekbd3.c

/* Author: Howard Chu <hyc@symas.com> 2023-05-20
 *
 * monitor keyboard activity and toggle keyboard backlight
 * for Lenovo Legion 7 gen6.
 */
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <poll.h>
#include <signal.h>

#include <sys/socket.h>
#include <netinet/in.h>

#include <sys/ioctl.h>
#include <linux/kd.h>

#define DEFPORT	6742

#define NET_PACKET_ID_RGBCONTROLLER_UPDATEZONELEDS	1051	/* OpenRGB NetworkProtocol.h */
#define ZONECOLORS	143

static char dummybuf[8192];

unsigned short port = DEFPORT;
struct sockaddr_in sa;

int kbdfd;
int oldkbmode;

/** @brief How many milliseconds before turning off kbd light */
#ifndef IDLE_MSEC
#define IDLE_MSEC	7000
#endif

typedef struct header {
	char magic[4];
	unsigned int dev_idx;
	unsigned int id;
	unsigned int size;
} header;

typedef struct msgdata {
	unsigned int size2;
	unsigned int zone;
	unsigned short num;
	unsigned short color[ZONECOLORS*2];
} msgdata;

typedef struct msgpkt {
	header hdr;
	msgdata dat;
} msgpkt;

static void die(int x)
{
	ioctl(kbdfd, KDSKBMODE, oldkbmode);
	exit(1);
}

int main(int argc, char *argv[])
{
	struct pollfd pfd;
	int rc, blfd, scfd;
	int brt, timeout, prev = -1;
	int maxbrt;
	char bm[2] = "0\n";
	msgpkt msg = {{{'O','R','G','B'},0,NET_PACKET_ID_RGBCONTROLLER_UPDATEZONELEDS, sizeof(msgdata)},
		{sizeof(msgdata),0,ZONECOLORS}};

	/* Get max brightness */
	scfd = open("/sys/class/backlight/amdgpu_bl1/max_brightness", O_RDONLY);
	read(scfd, dummybuf, sizeof(dummybuf));
	maxbrt = atoi(dummybuf);
	close(scfd);

	scfd = open("/sys/class/backlight/amdgpu_bl1/brightness", O_RDONLY);

	/* Connect to OpenRGB SDK */
	blfd = socket(PF_INET, SOCK_STREAM, 0);
	sa.sin_family = AF_INET;
	sa.sin_port = htons(port);
	sa.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
	if (connect(blfd, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
		perror("connect");
		exit(1);
	}

/*	pfd.fd = open("/dev/input/by-path/platform-i8042-serio-0-event-kbd", O_RDONLY); */
	pfd.fd = open("/dev/tty0", O_RDONLY);
	kbdfd = pfd.fd;
	pfd.events = POLLIN;

	ioctl(kbdfd, KDGKBMODE, &oldkbmode);

	signal(SIGINT, die);

	ioctl(kbdfd, KDSKBMODE, K_RAW);

	timeout = IDLE_MSEC;
	while (1) {
		rc = poll(&pfd, 1, timeout);
		/* Kbd colors range from 0 to 255.
		 * Screen brightness ranges from 0 to 255.
		 * Consider making the keyboard brightness
		 * depend on the screen brightness.
		 *
		 * Assume 255 means working in a bright room.
		 * In that case, leave the kbd light off.
		 * Otherwise, use screen brightness as kbd brightness.
		 */
		if (rc) {
			/* got keyboard input, flush it all and
			 * wait for the next event. Also check
			 * the screen brightness and set the kbd
			 * backlight accordingly.
			 */
			read(pfd.fd, dummybuf, sizeof(dummybuf));
			timeout = IDLE_MSEC;
			read(scfd, dummybuf, sizeof(dummybuf));
			lseek(scfd, 0, SEEK_SET);
			brt = atoi(dummybuf);
			if (brt == maxbrt) {
				brt = 0;
			}
		} else {
			/* soft fade out */
			brt >>= 1;
			timeout = brt ? 100 : -1;
			/* once we've gotten a timeout, turn off
			 * kbd backlight and wait forever for
			 * the next keypress
			 */
		}
		if (brt == prev)
			continue;
		{int i;
			unsigned short *c = msg.dat.color;
			for (i=0; i<ZONECOLORS; i++) {
				*c++ = brt<<8;
				*c++ = brt;
			}
		}
		write(blfd, &msg, sizeof(msg));
		prev = brt;
	}
}