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authorVincent Mailhol <mailhol.vincent@wanadoo.fr>2021-01-11 17:19:25 +0300
committerMarc Kleine-Budde <mkl@pengutronix.de>2021-01-14 10:43:42 +0300
commit85d99c3e2a13d542445342a1383a686dadeaac3d (patch)
tree42706b247155123be6686f480f3ceb23315ce647 /include/linux/can
parent99b7beb0431a4b9728023e9169ed15af678d2c7f (diff)
downloadlinux-85d99c3e2a13d542445342a1383a686dadeaac3d.tar.xz
can: length: can_skb_get_frame_len(): introduce function to get data length of frame in data link layer
This patch adds the function can_skb_get_frame_len() which returns the length of a CAN frame on the data link layer, including Start-of-frame, Identifier, various other bits, the actual data, the CRC, the End-of-frame, the Inter frame spacing. Co-developed-by: Arunachalam Santhanam <arunachalam.santhanam@in.bosch.com> Signed-off-by: Arunachalam Santhanam <arunachalam.santhanam@in.bosch.com> Co-developed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Co-developed-by: Marc Kleine-Budde <mkl@pengutronix.de> Link: https://lore.kernel.org/r/20210111141930.693847-11-mkl@pengutronix.de Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'include/linux/can')
-rw-r--r--include/linux/can/length.h120
1 files changed, 120 insertions, 0 deletions
diff --git a/include/linux/can/length.h b/include/linux/can/length.h
index b2313b2a0b02..6995092b774e 100644
--- a/include/linux/can/length.h
+++ b/include/linux/can/length.h
@@ -1,11 +1,128 @@
/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (C) 2020 Oliver Hartkopp <socketcan@hartkopp.net>
+ * Copyright (C) 2020 Marc Kleine-Budde <kernel@pengutronix.de>
*/
#ifndef _CAN_LENGTH_H
#define _CAN_LENGTH_H
/*
+ * Size of a Classical CAN Standard Frame
+ *
+ * Name of Field Bits
+ * ---------------------------------------------------------
+ * Start-of-frame 1
+ * Identifier 11
+ * Remote transmission request (RTR) 1
+ * Identifier extension bit (IDE) 1
+ * Reserved bit (r0) 1
+ * Data length code (DLC) 4
+ * Data field 0...64
+ * CRC 15
+ * CRC delimiter 1
+ * ACK slot 1
+ * ACK delimiter 1
+ * End-of-frame (EOF) 7
+ * Inter frame spacing 3
+ *
+ * rounded up and ignoring bitstuffing
+ */
+#define CAN_FRAME_OVERHEAD_SFF DIV_ROUND_UP(47, 8)
+
+/*
+ * Size of a Classical CAN Extended Frame
+ *
+ * Name of Field Bits
+ * ---------------------------------------------------------
+ * Start-of-frame 1
+ * Identifier A 11
+ * Substitute remote request (SRR) 1
+ * Identifier extension bit (IDE) 1
+ * Identifier B 18
+ * Remote transmission request (RTR) 1
+ * Reserved bits (r1, r0) 2
+ * Data length code (DLC) 4
+ * Data field 0...64
+ * CRC 15
+ * CRC delimiter 1
+ * ACK slot 1
+ * ACK delimiter 1
+ * End-of-frame (EOF) 7
+ * Inter frame spacing 3
+ *
+ * rounded up and ignoring bitstuffing
+ */
+#define CAN_FRAME_OVERHEAD_EFF DIV_ROUND_UP(67, 8)
+
+/*
+ * Size of a CAN-FD Standard Frame
+ *
+ * Name of Field Bits
+ * ---------------------------------------------------------
+ * Start-of-frame 1
+ * Identifier 11
+ * Reserved bit (r1) 1
+ * Identifier extension bit (IDE) 1
+ * Flexible data rate format (FDF) 1
+ * Reserved bit (r0) 1
+ * Bit Rate Switch (BRS) 1
+ * Error Status Indicator (ESI) 1
+ * Data length code (DLC) 4
+ * Data field 0...512
+ * Stuff Bit Count (SBC) 0...16: 4 20...64:5
+ * CRC 0...16: 17 20...64:21
+ * CRC delimiter (CD) 1
+ * ACK slot (AS) 1
+ * ACK delimiter (AD) 1
+ * End-of-frame (EOF) 7
+ * Inter frame spacing 3
+ *
+ * assuming CRC21, rounded up and ignoring bitstuffing
+ */
+#define CANFD_FRAME_OVERHEAD_SFF DIV_ROUND_UP(61, 8)
+
+/*
+ * Size of a CAN-FD Extended Frame
+ *
+ * Name of Field Bits
+ * ---------------------------------------------------------
+ * Start-of-frame 1
+ * Identifier A 11
+ * Substitute remote request (SRR) 1
+ * Identifier extension bit (IDE) 1
+ * Identifier B 18
+ * Reserved bit (r1) 1
+ * Flexible data rate format (FDF) 1
+ * Reserved bit (r0) 1
+ * Bit Rate Switch (BRS) 1
+ * Error Status Indicator (ESI) 1
+ * Data length code (DLC) 4
+ * Data field 0...512
+ * Stuff Bit Count (SBC) 0...16: 4 20...64:5
+ * CRC 0...16: 17 20...64:21
+ * CRC delimiter (CD) 1
+ * ACK slot (AS) 1
+ * ACK delimiter (AD) 1
+ * End-of-frame (EOF) 7
+ * Inter frame spacing 3
+ *
+ * assuming CRC21, rounded up and ignoring bitstuffing
+ */
+#define CANFD_FRAME_OVERHEAD_EFF DIV_ROUND_UP(80, 8)
+
+/*
+ * Maximum size of a Classical CAN frame
+ * (rounded up and ignoring bitstuffing)
+ */
+#define CAN_FRAME_LEN_MAX (CAN_FRAME_OVERHEAD_EFF + CAN_MAX_DLEN)
+
+/*
+ * Maximum size of a CAN-FD frame
+ * (rounded up and ignoring bitstuffing)
+ */
+#define CANFD_FRAME_LEN_MAX (CANFD_FRAME_OVERHEAD_EFF + CANFD_MAX_DLEN)
+
+/*
* can_cc_dlc2len(value) - convert a given data length code (dlc) of a
* Classical CAN frame into a valid data length of max. 8 bytes.
*
@@ -45,6 +162,9 @@ u8 can_fd_dlc2len(u8 dlc);
/* map the sanitized data length to an appropriate data length code */
u8 can_fd_len2dlc(u8 len);
+/* calculate the CAN Frame length in bytes of a given skb */
+unsigned int can_skb_get_frame_len(const struct sk_buff *skb);
+
/* map the data length to an appropriate data link layer length */
static inline u8 canfd_sanitize_len(u8 len)
{