can: use frame len instead of can_dlc

RIOT implementation of CAN bus relies on SocketCAN model.
Since commit c398e56 (can: add optional DLC element to Classical CAN
frame structure), '__u8 can_dlc' attribute of struct can_frame is
considered as deprecated in SocketCAN and kept for legacy support.
Attribute '__u8 len' should be used instead.

	union {
		/* CAN frame payload length in byte (0 .. CAN_MAX_DLEN)
		 * was previously named can_dlc so we need to carry that
		 * name for legacy support
		 */
		__u8 len;
		__u8 can_dlc; /* deprecated */
	};

Moreover, CAN FD frame structure does not support legacy attribute
'can_dlc', making 'len' mandatory for incoming CAN FD support in RIOT.

	struct canfd_frame {
		canid_t can_id;  /* 32 bit CAN_ID + EFF/RTR/ERR flags */
		__u8    len;     /* frame payload length in byte */
		__u8    flags;   /* additional flags for CAN FD */
		__u8    __res0;  /* reserved / padding */
		__u8    __res1;  /* reserved / padding */
		__u8    data[CANFD_MAX_DLEN]
__attribute__((aligned(8)));
	};

Signed-off-by: Gilles DOFFE <gilles.doffe@rtone.fr>

cpu/esp32/periph/can.c

@@ -240,7 +240,7 @@ static int _esp_can_send(candev_t *candev, const struct can_frame *frame)
     /* prepare the frame as expected by ESP32 */
     twai_hal_frame_t esp_frame = { };
 
-    esp_frame.dlc = frame->can_dlc;
+    esp_frame.dlc = frame->len;
     esp_frame.rtr = (frame->can_id & CAN_RTR_FLAG);
     esp_frame.frame_format = (frame->can_id & CAN_EFF_FLAG);
 
@@ -825,7 +825,7 @@ static void IRAM_ATTR _esp_can_intr_handler(void *arg)
                 }
                 frame.can_id |= esp_frame.rtr ? CAN_RTR_FLAG : 0;
                 frame.can_id |= esp_frame.frame_format ? CAN_EFF_FLAG : 0;
-                frame.can_dlc = esp_frame.dlc;
+                frame.len = esp_frame.dlc;
 
                 /* apply acceptance filters only if they are set */
                 unsigned f_id = 0;

cpu/native/periph/can.c

@@ -217,7 +217,7 @@ static int _send(candev_t *candev, const struct can_frame *frame)
 
     nbytes = real_write(dev->sock, frame, sizeof(struct can_frame));
 
-    if (nbytes < frame->can_dlc) {
+    if (nbytes < frame->len) {
         real_printf("CAN write op failed, nbytes=%i\n", nbytes);
         return -1;
     }

cpu/stm32/periph/can.c

@@ -412,14 +412,14 @@ static int _send(candev_t *candev, const struct can_frame *frame)
     else {
         can->sTxMailBox[mailbox].TIR = (frame->can_id & CAN_SFF_MASK) << CAN_TIxR_SFF_SHIFT;
     }
-    can->sTxMailBox[mailbox].TDTR = frame->can_dlc & CAN_TDT0R_DLC;
+    can->sTxMailBox[mailbox].TDTR = frame->len & CAN_TDT0R_DLC;
 
     can->sTxMailBox[mailbox].TDLR = 0;
     can->sTxMailBox[mailbox].TDHR = 0;
-    for (int j = 0; j < 4 && frame->can_dlc > j; j++) {
+    for (int j = 0; j < 4 && frame->len > j; j++) {
         can->sTxMailBox[mailbox].TDLR |= (uint32_t)(frame->data[j] << (8 * j));
     }
-    for (int j = 4; j < 8 && frame->can_dlc > j; j++) {
+    for (int j = 4; j < 8 && frame->len > j; j++) {
         can->sTxMailBox[mailbox].TDHR |= (uint32_t)(frame->data[j] << (8 * (j - 4)));
     }
 
@@ -470,7 +470,7 @@ static int read_frame(can_t *dev, struct can_frame *frame, int mailbox)
     }
 
     /* Get DLC */
-    frame->can_dlc = can->sFIFOMailBox[mailbox].RDTR & CAN_RDT0R_DLC;
+    frame->len = can->sFIFOMailBox[mailbox].RDTR & CAN_RDT0R_DLC;
 
     /* Get Data */
     for (int j = 0; j < 4; j++) {

drivers/mcp2515/mcp2515.c

@@ -40,7 +40,7 @@
 #define MCP2515_TX_CTRL(mailbox) ((MCP2515_TXB0CTRL) + ((mailbox) << 4))
 #define MCP2515_RX_CTRL(mailbox) ((MCP2515_RXB0CTRL) + ((mailbox) << 4))
 
-/* length of the fixed part of a can message: 4 bytes can_id + 1 byte can_dlc */
+/* length of the fixed part of a can message: 4 bytes can_id + 1 byte len */
 #define CAN_FIXED_LEN 5
 
 /* oscillator startup time
@@ -165,13 +165,13 @@ int mcp2515_send(candev_mcp2515_t *dev, const struct can_frame *frame,
 
     struct can_frame framebuf;
 
-    if (frame->can_dlc > CAN_MAX_DLEN) {
+    if (frame->len > CAN_MAX_DLEN) {
         return -1;
     }
 
     framebuf.can_id = frame->can_id;
-    framebuf.can_dlc = frame->can_dlc;
+    framebuf.len = frame->len;
-    for (int i = 0; i < framebuf.can_dlc; i++) {
+    for (int i = 0; i < framebuf.len; i++) {
         framebuf.data[i] = frame->data[i];
     }
 
@@ -192,14 +192,14 @@ int mcp2515_send(candev_mcp2515_t *dev, const struct can_frame *frame,
         _fill_standard_id(framebuf.can_id, outbuf);
     }
 
-    outbuf[4] = framebuf.can_dlc;
+    outbuf[4] = framebuf.len;
-    memcpy(&outbuf[CAN_FIXED_LEN], framebuf.data, framebuf.can_dlc);
+    memcpy(&outbuf[CAN_FIXED_LEN], framebuf.data, framebuf.len);
 
     /* set mailbox priority */
     mcp2515_spi_write(dev, MCP2515_TX_CTRL(mailbox), &prio, 1);
 
     mcp2515_spi_write_txbuf(dev, mailbox, outbuf,
-                            CAN_FIXED_LEN + framebuf.can_dlc);
+                            CAN_FIXED_LEN + framebuf.len);
     _mcp2515_enable_irq(dev, MCP2515_CANINTE_TX0IE << mailbox);
     mcp2515_spi_rts(dev, mailbox);
 
@@ -228,8 +228,8 @@ int mcp2515_receive(candev_mcp2515_t *dev, struct can_frame *frame, int mailbox)
                         (((uint32_t)inbuf[1] & 0xE0) >> 5);
     }
 
-    frame->can_dlc = inbuf[4];
+    frame->len = inbuf[4];
-    memcpy(frame->data, inbuf + 5, frame->can_dlc);
+    memcpy(frame->data, inbuf + 5, frame->len);
     return mailbox;
 }
 

sys/can/isotp/isotp.c

@@ -197,7 +197,7 @@ static int _isotp_rcv_fc(struct isotp *isotp, struct can_frame *frame, int ae)
 
     ztimer_remove(ZTIMER_USEC, &isotp->tx_timer);
 
-    if (frame->can_dlc < ae + FC_CONTENT_SZ) {
+    if (frame->len < ae + FC_CONTENT_SZ) {
         /* Invalid length */
         isotp->tx.state = ISOTP_IDLE;
         return 1;
@@ -260,7 +260,7 @@ static int _isotp_rcv_sf(struct isotp *isotp, struct can_frame *frame, int ae)
     isotp->rx.state = ISOTP_IDLE;
 
     int len = (frame->data[ae] & 0x0F);
-    if (len > frame->can_dlc - (SF_PCI_SZ + ae)) {
+    if (len > frame->len - (SF_PCI_SZ + ae)) {
         return 1;
     }
 
@@ -307,7 +307,7 @@ static int _isotp_rcv_ff(struct isotp *isotp, struct can_frame *frame, int ae)
     isotp->rx.snip = snip;
 
     isotp->rx.idx = 0;
-    for (int i = ae + FF_PCI_SZ; i < frame->can_dlc; i++) {
+    for (int i = ae + FF_PCI_SZ; i < frame->len; i++) {
         ((uint8_t *)isotp->rx.snip->data)[isotp->rx.idx++] = frame->data[i];
     }
 
@@ -352,7 +352,7 @@ static int _isotp_rcv_cf(struct isotp *isotp, struct can_frame *frame, int ae)
     isotp->rx.sn++;
     isotp->rx.sn %= 16;
 
-    for (int i = ae + N_PCI_SZ; i < frame->can_dlc; i++) {
+    for (int i = ae + N_PCI_SZ; i < frame->len; i++) {
         ((uint8_t *)isotp->rx.snip->data)[isotp->rx.idx++] = frame->data[i];
         if (isotp->rx.idx >= isotp->rx.snip->size) {
             break;
@@ -393,7 +393,7 @@ static int _isotp_rcv(struct isotp *isotp, struct can_frame *frame)
 
     if (IS_ACTIVE(ENABLE_DEBUG)) {
         DEBUG("_isotp_rcv: id=%" PRIx32 " data=", frame->can_id);
-        for (int i = 0; i < frame->can_dlc; i++) {
+        for (int i = 0; i < frame->len; i++) {
             DEBUG("%02hhx", frame->data[i]);
         }
         DEBUG("\n");
@@ -431,10 +431,10 @@ static int _isotp_send_fc(struct isotp *isotp, int ae, uint8_t status)
 
     if (isotp->opt.flags & CAN_ISOTP_TX_PADDING) {
         memset(fc.data, isotp->opt.txpad_content, CAN_MAX_DLEN);
-        fc.can_dlc = CAN_MAX_DLEN;
+        fc.len = CAN_MAX_DLEN;
     }
     else {
-        fc.can_dlc = ae + FC_CONTENT_SZ;
+        fc.len = ae + FC_CONTENT_SZ;
     }
 
     fc.data[ae] = N_PCI_FC | status;
@@ -449,7 +449,7 @@ static int _isotp_send_fc(struct isotp *isotp, int ae, uint8_t status)
 
     if (IS_ACTIVE(ENABLE_DEBUG)) {
         DEBUG("_isotp_send_fc: id=%" PRIx32 " data=", fc.can_id);
-        for (int i = 0; i < fc.can_dlc; i++) {
+        for (int i = 0; i < fc.len; i++) {
             DEBUG("%02hhx", fc.data[i]);
         }
         DEBUG("\n");
@@ -472,7 +472,7 @@ static void _isotp_create_ff(struct isotp *isotp, struct can_frame *frame, int a
 {
 
     frame->can_id = isotp->opt.tx_id;
-    frame->can_dlc = CAN_MAX_DLEN;
+    frame->len = CAN_MAX_DLEN;
 
     if (ae) {
         frame->data[0] = isotp->opt.ext_address;
@@ -495,15 +495,15 @@ static void _isotp_fill_dataframe(struct isotp *isotp, struct can_frame *frame,
     size_t num_bytes = MIN(space, isotp->tx.snip->size - isotp->tx.idx);
 
     frame->can_id = isotp->opt.tx_id;
-    frame->can_dlc = num_bytes + pci_len;
+    frame->len = num_bytes + pci_len;
 
     DEBUG("_isotp_fill_dataframe: num_bytes=%" PRIuSIZE ", pci_len=%" PRIuSIZE "\n",
           num_bytes, pci_len);
 
     if (num_bytes < space) {
         if (isotp->opt.flags & CAN_ISOTP_TX_PADDING) {
-            frame->can_dlc = CAN_MAX_DLEN;
+            frame->len = CAN_MAX_DLEN;
-            memset(frame->data, isotp->opt.txpad_content, frame->can_dlc);
+            memset(frame->data, isotp->opt.txpad_content, frame->len);
         }
     }
 

sys/shell/cmds/conn_can.c

@@ -67,8 +67,8 @@ static int _send(int argc, char **argv)
         return 1;
     }
     frame.can_id = strtoul(argv[2], NULL, 16);
-    frame.can_dlc = argc - 3;
+    frame.len = argc - 3;
-    for (int i = 0; i < frame.can_dlc; i++) {
+    for (int i = 0; i < frame.len; i++) {
         frame.data[i] = strtoul(argv[3 + i], NULL, 16);
     }
     conn_can_raw_create(&conn, NULL, 0, ifnum, 0);
@@ -133,8 +133,8 @@ static int _dump(int argc, char **argv)
            == sizeof(struct can_frame))) {
         printf("%-8s(%d) %8" PRIX32 "  [%x] ",
                raw_can_get_name_by_ifnum(ifnum), ifnum,
-               frame.can_id, frame.can_dlc);
+               frame.can_id, frame.len);
-        for (int i = 0; i < frame.can_dlc; i++) {
+        for (int i = 0; i < frame.len; i++) {
             printf(" %02X", frame.data[i]);
         }
         printf("\n");

tests/drivers/candev/main.c

@@ -69,7 +69,7 @@ static int _send(int argc, char **argv)
 
     struct can_frame frame = {
         .can_id = 1,
-        .can_dlc = 3,
+        .len = 3,
         .data[0] = 0xAB,
         .data[1] = 0xCD,
         .data[2] = 0xEF,
@@ -83,7 +83,7 @@ static int _send(int argc, char **argv)
         for (int i = 1; i < argc; i++) {
             frame.data[i - 1] = atoi(argv[i]);
         }
-        frame.can_dlc = argc - 1;
+        frame.len = argc - 1;
     }
 
     ret = candev->driver->send(candev, &frame);
@@ -115,12 +115,12 @@ static int _receive(int argc, char **argv)
         puts("Reading from Rxbuf...");
         isrpipe_read(&rxbuf, (uint8_t *)&(frame.can_id), sizeof(frame.can_id));
         frame.can_id &= 0x1FFFFFFF; /* clear invalid bits */
-        isrpipe_read(&rxbuf, (uint8_t *)&(frame.can_dlc), 1);
+        isrpipe_read(&rxbuf, (uint8_t *)&(frame.len), 1);
-        printf("id: %" PRIx32 " dlc: %" PRIx8, frame.can_id, frame.can_dlc);
+        printf("id: %" PRIx32 " dlc: %" PRIx8, frame.can_id, frame.len);
-        if (frame.can_dlc > 0) {
+        if (frame.len > 0) {
             printf(" data: ");
-            isrpipe_read(&rxbuf, frame.data, frame.can_dlc); /* data */
+            isrpipe_read(&rxbuf, frame.data, frame.len); /* data */
-            for (int i = 0; i < frame.can_dlc; i++) {
+            for (int i = 0; i < frame.len; i++) {
                 printf("0x%X ", frame.data[i]);
             }
         }
@@ -240,16 +240,16 @@ static void _can_event_callback(candev_t *dev, candev_event_t event, void *arg)
         frame = (struct can_frame *)arg;
 
         DEBUG("            id: %" PRIx32 " dlc: %u data: ", frame->can_id & 0x1FFFFFFF,
-              frame->can_dlc);
+              frame->len);
-        for (uint8_t i = 0; i < frame->can_dlc; i++) {
+        for (uint8_t i = 0; i < frame->len; i++) {
             DEBUG("0x%X ", frame->data[i]);
         }
         DEBUG_PUTS("");
 
         /* Store in buffer until user requests the data */
         isrpipe_write(&rxbuf, (uint8_t *)&(frame->can_id), sizeof(frame->can_id));
-        isrpipe_write_one(&rxbuf, frame->can_dlc);
+        isrpipe_write_one(&rxbuf, frame->len);
-        isrpipe_write(&rxbuf, frame->data, frame->can_dlc);
+        isrpipe_write(&rxbuf, frame->data, frame->len);
 
         break;
     case CANDEV_EVENT_RX_ERROR:

tests/sys/conn_can/main.c

@@ -145,22 +145,22 @@ static int _send(int argc, char **argv, bool rtr)
 
     if (rtr) {
         frame.can_id = CAN_RTR_FLAG | strtoul(argv[3], NULL, 16);
-        frame.can_dlc = strtoul(argv[4], NULL, 10);
+        frame.len = strtoul(argv[4], NULL, 10);
     } else {
         frame.can_id = strtoul(argv[3], NULL, 16);
-        frame.can_dlc = argc - 4;
+        frame.len = argc - 4;
     }
-    if (frame.can_dlc > 8) {
+    if (frame.len > 8) {
         puts("Invalid length");
         return 1;
     }
 
     if (rtr) {
-        for (int i = 0; i < frame.can_dlc; i++) {
+        for (int i = 0; i < frame.len; i++) {
             frame.data[i] = 0x0;
         }
     } else {
-        for (int i = 0; i < frame.can_dlc; i++) {
+        for (int i = 0; i < frame.len; i++) {
             frame.data[i] = strtol(argv[4 + i], NULL, 16);
         }
     }
@@ -614,8 +614,8 @@ static void *_receive_thread(void *args)
                        thread_nb,
                        raw_can_get_name_by_ifnum(conn[thread_nb].ifnum),
                        frame.can_id,
-                       frame.can_dlc);
+                       frame.len);
-                for (int i = 0; i < frame.can_dlc; i++) {
+                for (int i = 0; i < frame.len; i++) {
                     printf(" %02X", frame.data[i]);
                 }
                 printf("\n");