diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7088c51..a4e8484 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -33,6 +33,7 @@ set(PROGRAMS_CANLIB
     cansequence
     log2asc
     log2long
+    slcanpty
 )
 
 set(PROGRAMS_J1939
@@ -58,7 +59,6 @@ set(PROGRAMS
     isotptun
     slcan_attach
     slcand
-    slcanpty
 )
 
 add_executable(can-calc-bit-timing
diff --git a/Makefile b/Makefile
index 970a4cb..529343d 100644
--- a/Makefile
+++ b/Makefile
@@ -46,6 +46,7 @@ MAKEFLAGS := -k
 CFLAGS := -O2 -Wall -Wno-parentheses
 
 CPPFLAGS += \
+	-I. \
 	-Iinclude \
 	-DAF_CAN=PF_CAN \
 	-DPF_CAN=29 \
@@ -119,6 +120,7 @@ canplayer.o:	lib.h
 cansend.o:	lib.h
 log2asc.o:	lib.h
 log2long.o:	lib.h
+slcanpty.o:	lib.h
 j1939acd.o:	libj1939.h
 j1939cat.o:	libj1939.h
 j1939spy.o:	libj1939.h
@@ -135,6 +137,7 @@ cansend:	cansend.o	lib.o
 cansequence:	cansequence.o	lib.o
 log2asc:	log2asc.o	lib.o
 log2long:	log2long.o	lib.o
+slcanpty:	slcanpty.o	lib.o
 j1939acd:	j1939acd.o	libj1939.o
 j1939cat:	j1939cat.o	libj1939.o
 j1939spy:	j1939spy.o	libj1939.o
diff --git a/canbusload.c b/canbusload.c
index e4dfc02..47b62fd 100644
--- a/canbusload.c
+++ b/canbusload.c
@@ -61,6 +61,7 @@
 #include <linux/can.h>
 #include <linux/can/raw.h>
 
+#include "lib.h"
 #include "terminal.h"
 #include "canframelen.h"
 
@@ -310,9 +311,7 @@ int main(int argc, char **argv)
 			return 1;
 		}
 
-#ifdef DEBUG
-		printf("open %d '%s'.\n", i, ptr);
-#endif
+		pr_debug("open %d '%s'.\n", i, ptr);
 
 		s[i] = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 		if (s[i] < 0) {
@@ -358,10 +357,8 @@ int main(int argc, char **argv)
 		if (nbytes > max_bitrate_len)
 			max_bitrate_len = nbytes; /* for nice printing */
 
+		pr_debug("using interface name '%s'.\n", ifr.ifr_name);
 
-#ifdef DEBUG
-		printf("using interface name '%s'.\n", ifr.ifr_name);
-#endif
 		/* try to switch the socket into CAN FD mode */
 		const int canfd_on = 1;
 		setsockopt(s[i], SOL_CAN_RAW, CAN_RAW_FD_FRAMES, &canfd_on, sizeof(canfd_on));
diff --git a/candump.c b/candump.c
index 680166f..ff646e7 100644
--- a/candump.c
+++ b/candump.c
@@ -63,6 +63,7 @@
 
 #include <linux/can.h>
 #include <linux/can/raw.h>
+#include <linux/net_tstamp.h>
 
 #include "terminal.h"
 #include "lib.h"
@@ -72,10 +73,6 @@
 #define SO_TIMESTAMPING 37
 #endif
 
-/* from #include <linux/net_tstamp.h> - since Linux 2.6.30 */
-#define SOF_TIMESTAMPING_SOFTWARE (1 << 4)
-#define SOF_TIMESTAMPING_RX_SOFTWARE (1 << 3)
-#define SOF_TIMESTAMPING_RAW_HARDWARE (1 << 6)
 #define TIMESTAMPSZ 50 /* string 'absolute with date' requires max 49 bytes */
 
 #define MAXSOCK 16    /* max. number of CAN interfaces given on the cmdline */
@@ -108,6 +105,7 @@ struct if_info { /* bundled information per open socket */
 };
 static struct if_info sock_info[MAXSOCK];
 
+static char *progname;
 static char devname[MAXIFNAMES][IFNAMSIZ+1];
 static int dindex[MAXIFNAMES];
 static int max_devname_len; /* to prevent frazzled device name output */
@@ -121,11 +119,11 @@ extern int optind, opterr, optopt;
 
 static volatile int running = 1;
 
-static void print_usage(char *prg)
+static void print_usage(void)
 {
-	fprintf(stderr, "%s - dump CAN bus traffic.\n", prg);
-	fprintf(stderr, "\nUsage: %s [options] <CAN interface>+\n", prg);
-	fprintf(stderr, "  (use CTRL-C to terminate %s)\n\n", prg);
+	fprintf(stderr, "%s - dump CAN bus traffic.\n", progname);
+	fprintf(stderr, "\nUsage: %s [options] <CAN interface>+\n", progname);
+	fprintf(stderr, "  (use CTRL-C to terminate %s)\n\n", progname);
 	fprintf(stderr, "Options:\n");
 	fprintf(stderr, "         -t <type>   (timestamp: (a)bsolute/(d)elta/(z)ero/(A)bsolute w date)\n");
 	fprintf(stderr, "         -H          (read hardware timestamps instead of system timestamps)\n");
@@ -159,12 +157,12 @@ static void print_usage(char *prg)
 	fprintf(stderr, "Without any given filter all data frames are received ('0:0' default filter).\n");
 	fprintf(stderr, "\nUse interface name '%s' to receive from all CAN interfaces.\n", ANYDEV);
 	fprintf(stderr, "\nExamples:\n");
-	fprintf(stderr, "%s -c -c -ta can0,123:7FF,400:700,#000000FF can2,400~7F0 can3 can8\n\n", prg);
-	fprintf(stderr, "%s -l any,0~0,#FFFFFFFF\n         (log only error frames but no(!) data frames)\n", prg);
-	fprintf(stderr, "%s -l any,0:0,#FFFFFFFF\n         (log error frames and also all data frames)\n", prg);
-	fprintf(stderr, "%s vcan2,12345678:DFFFFFFF\n         (match only for extended CAN ID 12345678)\n", prg);
-	fprintf(stderr, "%s vcan2,123:7FF\n         (matches CAN ID 123 - including EFF and RTR frames)\n", prg);
-	fprintf(stderr, "%s vcan2,123:C00007FF\n         (matches CAN ID 123 - only SFF and non-RTR frames)\n", prg);
+	fprintf(stderr, "%s -c -c -ta can0,123:7FF,400:700,#000000FF can2,400~7F0 can3 can8\n\n", progname);
+	fprintf(stderr, "%s -l any,0~0,#FFFFFFFF\n         (log only error frames but no(!) data frames)\n", progname);
+	fprintf(stderr, "%s -l any,0:0,#FFFFFFFF\n         (log error frames and also all data frames)\n", progname);
+	fprintf(stderr, "%s vcan2,12345678:DFFFFFFF\n         (match only for extended CAN ID 12345678)\n", progname);
+	fprintf(stderr, "%s vcan2,123:7FF\n         (matches CAN ID 123 - including EFF and RTR frames)\n", progname);
+	fprintf(stderr, "%s vcan2,123:C00007FF\n         (matches CAN ID 123 - only SFF and non-RTR frames)\n", progname);
 	fprintf(stderr, "\n");
 }
 
@@ -216,9 +214,7 @@ static int idx2dindex(int ifidx, int socket)
 
 	strcpy(devname[i], ifr.ifr_name);
 
-#ifdef DEBUG
-	printf("new index %d (%s)\n", i, devname[i]);
-#endif
+	pr_debug("new index %d (%s)\n", i, devname[i]);
 
 	return i;
 }
@@ -327,6 +323,8 @@ int main(int argc, char **argv)
 	last_tv.tv_sec = 0;
 	last_tv.tv_usec = 0;
 
+	progname = basename(argv[0]);
+
 	while ((opt = getopt(argc, argv, "t:HciaSs:lDdxLf:n:r:he8T:?")) != -1) {
 		switch (opt) {
 		case 't':
@@ -335,7 +333,7 @@ int main(int argc, char **argv)
 			if ((timestamp != 'a') && (timestamp != 'A') &&
 			    (timestamp != 'd') && (timestamp != 'z')) {
 				fprintf(stderr, "%s: unknown timestamp mode '%c' - ignored\n",
-					basename(argv[0]), optarg[0]);
+					progname, optarg[0]);
 				timestamp = 0;
 			}
 			if ((logtimestamp != 'a') && (logtimestamp != 'z')) {
@@ -374,7 +372,7 @@ int main(int argc, char **argv)
 		case 's':
 			silent = atoi(optarg);
 			if (silent > SILENT_ON) {
-				print_usage(basename(argv[0]));
+				print_usage();
 				exit(1);
 			}
 			break;
@@ -407,7 +405,7 @@ int main(int argc, char **argv)
 		case 'n':
 			count = atoi(optarg);
 			if (count < 1) {
-				print_usage(basename(argv[0]));
+				print_usage();
 				exit(1);
 			}
 			break;
@@ -415,7 +413,7 @@ int main(int argc, char **argv)
 		case 'r':
 			rcvbuf_size = atoi(optarg);
 			if (rcvbuf_size < 1) {
-				print_usage(basename(argv[0]));
+				print_usage();
 				exit(1);
 			}
 			break;
@@ -424,19 +422,19 @@ int main(int argc, char **argv)
 			errno = 0;
 			timeout_ms = strtol(optarg, NULL, 0);
 			if (errno != 0) {
-				print_usage(basename(argv[0]));
+				print_usage();
 				exit(1);
 			}
 			break;
 		default:
-			print_usage(basename(argv[0]));
+			print_usage();
 			exit(1);
 			break;
 		}
 	}
 
 	if (optind == argc) {
-		print_usage(basename(argv[0]));
+		print_usage();
 		exit(0);
 	}
 
@@ -477,9 +475,7 @@ int main(int argc, char **argv)
 		ptr = argv[optind+i];
 		nptr = strchr(ptr, ',');
 
-#ifdef DEBUG
-		printf("open %d '%s'.\n", i, ptr);
-#endif
+		pr_debug("open %d '%s'.\n", i, ptr);
 
 		obj->s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 		if (obj->s < 0) {
@@ -513,9 +509,7 @@ int main(int argc, char **argv)
 		memset(&ifr.ifr_name, 0, sizeof(ifr.ifr_name));
 		strncpy(ifr.ifr_name, ptr, nbytes);
 
-#ifdef DEBUG
-		printf("using interface name '%s'.\n", ifr.ifr_name);
-#endif
+		pr_debug("using interface name '%s'.\n", ifr.ifr_name);
 
 		if (strcmp(ANYDEV, ifr.ifr_name) != 0) {
 			if (ioctl(obj->s, SIOCGIFINDEX, &ifr) < 0) {
@@ -605,9 +599,7 @@ int main(int argc, char **argv)
 			/* try SO_RCVBUFFORCE first, if we run with CAP_NET_ADMIN */
 			if (setsockopt(obj->s, SOL_SOCKET, SO_RCVBUFFORCE,
 				       &rcvbuf_size, sizeof(rcvbuf_size)) < 0) {
-#ifdef DEBUG
-				printf("SO_RCVBUFFORCE failed so try SO_RCVBUF ...\n");
-#endif
+				pr_debug("SO_RCVBUFFORCE failed so try SO_RCVBUF ...\n");
 				if (setsockopt(obj->s, SOL_SOCKET, SO_RCVBUF,
 					       &rcvbuf_size, sizeof(rcvbuf_size)) < 0) {
 					perror("setsockopt SO_RCVBUF");
diff --git a/canlogserver.c b/canlogserver.c
index 6425ca4..51d548f 100644
--- a/canlogserver.c
+++ b/canlogserver.c
@@ -145,9 +145,7 @@ int idx2dindex(int ifidx, int socket)
 
 	strcpy(devname[i], ifr.ifr_name);
 
-#ifdef DEBUG
-	printf("new index %d (%s)\n", i, devname[i]);
-#endif
+	pr_debug("new index %d (%s)\n", i, devname[i]);
 
 	return i;
 }
@@ -310,11 +308,9 @@ int main(int argc, char **argv)
 
 	for (i=0; i<currmax; i++) {
 
-#ifdef DEBUG
-		printf("open %d '%s' m%08X v%08X i%d e%d.\n",
-		       i, argv[optind+i], mask[i], value[i],
-		       inv_filter[i], err_mask[i]);
-#endif
+		pr_debug("open %d '%s' m%08X v%08X i%d e%d.\n",
+		      i, argv[optind+i], mask[i], value[i],
+		      inv_filter[i], err_mask[i]);
 
 		if ((s[i] = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0) {
 			perror("socket");
diff --git a/include/linux/can/error.h b/include/linux/can/error.h
index 3463328..acc1ac3 100644
--- a/include/linux/can/error.h
+++ b/include/linux/can/error.h
@@ -57,6 +57,8 @@
 #define CAN_ERR_BUSOFF       0x00000040U /* bus off */
 #define CAN_ERR_BUSERROR     0x00000080U /* bus error (may flood!) */
 #define CAN_ERR_RESTARTED    0x00000100U /* controller restarted */
+#define CAN_ERR_CNT          0x00000200U /* TX error counter / data[6] */
+					 /* RX error counter / data[7] */
 
 /* arbitration lost in bit ... / data[0] */
 #define CAN_ERR_LOSTARB_UNSPEC   0x00 /* unspecified */
@@ -120,6 +122,22 @@
 #define CAN_ERR_TRX_CANL_SHORT_TO_GND  0x70 /* 0111 0000 */
 #define CAN_ERR_TRX_CANL_SHORT_TO_CANH 0x80 /* 1000 0000 */
 
-/* controller specific additional information / data[5..7] */
+/* data[5] is reserved (do not use) */
+
+/* TX error counter / data[6] */
+/* RX error counter / data[7] */
+
+/* CAN state thresholds
+ *
+ * Error counter	Error state
+ * -----------------------------------
+ * 0 -  95		Error-active
+ * 96 - 127		Error-warning
+ * 128 - 255		Error-passive
+ * 256 and greater	Bus-off
+ */
+#define CAN_ERROR_WARNING_THRESHOLD 96
+#define CAN_ERROR_PASSIVE_THRESHOLD 128
+#define CAN_BUS_OFF_THRESHOLD 256
 
 #endif /* _UAPI_CAN_ERROR_H */
diff --git a/lib.c b/lib.c
index 72afd79..ebad278 100644
--- a/lib.c
+++ b/lib.c
@@ -680,7 +680,7 @@ void snprintf_can_error_frame(char *buf, size_t len, const struct canfd_frame *c
 		}
 	}
 
-	if (cf->data[6] || cf->data[7]) {
+	if (cf->can_id & CAN_ERR_CNT || cf->data[6] || cf->data[7]) {
 		n += snprintf(buf + n, len - n, "%s", sep);
 		n += snprintf(buf + n, len - n, "error-counter-tx-rx{{%d}{%d}}",
 			      cf->data[6], cf->data[7]);
diff --git a/lib.h b/lib.h
index a4d3ce5..6cc58a2 100644
--- a/lib.h
+++ b/lib.h
@@ -47,6 +47,13 @@
 
 #include <stdio.h>
 
+#ifdef DEBUG
+#define pr_debug(fmt, args...) printf(fmt, ##args)
+#else
+__attribute__((format (printf, 1, 2)))
+static inline int pr_debug(const char* fmt, ...) {return 0;}
+#endif
+
 /* buffer sizes for CAN frame string representations */
 
 #define CL_ID (sizeof("12345678##1"))
diff --git a/mcp251xfd/mcp251xfd-dev-coredump.c b/mcp251xfd/mcp251xfd-dev-coredump.c
index 5874d24..680c734 100644
--- a/mcp251xfd/mcp251xfd-dev-coredump.c
+++ b/mcp251xfd/mcp251xfd-dev-coredump.c
@@ -17,18 +17,10 @@
 
 #include <linux/kernel.h>
 
+#include "lib.h"
 #include "mcp251xfd.h"
 #include "mcp251xfd-dump-userspace.h"
 
-#define pr_err(fmt, args...)    fprintf(stderr, fmt, ##args)
-#define pr_no(fmt, args...)     while (0) { fprintf(stdout, fmt, ##args); }
-
-#ifdef DEBUG
-#define pr_debug(fmt, args...) pr_err(fmt, ##args)
-#else
-#define pr_debug(fmt, args...) pr_no(fmt, ##args)
-#endif
-
 
 struct mcp251xfd_dump_iter {
 	const void *start;
diff --git a/slcanpty.c b/slcanpty.c
index e6f1efe..fa97cd6 100644
--- a/slcanpty.c
+++ b/slcanpty.c
@@ -43,27 +43,12 @@
 #include <linux/can/raw.h>
 #include <linux/sockios.h>
 
+#include "lib.h"
+
 /* maximum rx buffer len: extended CAN frame with timestamp */
 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
 #define DEVICE_NAME_PTMX "/dev/ptmx"
 
-#define DEBUG
-
-static int asc2nibble(char c)
-{
-
-	if ((c >= '0') && (c <= '9'))
-		return c - '0';
-
-	if ((c >= 'A') && (c <= 'F'))
-		return c - 'A' + 10;
-
-	if ((c >= 'a') && (c <= 'f'))
-		return c - 'a' + 10;
-
-	return 16; /* error */
-}
-
 /* read data from pty, send CAN frames to CAN socket and answer commands */
 int pty2can(int pty, int socket, struct can_filter *fi,
 	    int *is_open, int *tstamp)
@@ -119,14 +104,12 @@ rx_restart:
 	cmd = buf[0];
 	buf[nbytes] = 0;
 
-#ifdef DEBUG
 	for (tmp = 0; tmp < nbytes; tmp++)
 		if (buf[tmp] == '\r')
-			putchar('@');
+			pr_debug("@");
 		else
-			putchar(buf[tmp]);
-	printf("\n");
-#endif
+			pr_debug("%c", buf[tmp]);
+	pr_debug("\n");
 
 	/* check for filter configuration commands */
 	if (cmd == 'm' || cmd == 'M') {