Hi Marc,
nice cleanup!
On 09.01.21 18:40, Marc Kleine-Budde wrote:
This patch moves all CAN frame length related code of the CAN device
infrastructure into a separate file.
diff --git a/drivers/net/can/dev/length.c b/drivers/net/can/dev/length.c
new file mode 100644
index 000000000000..540d40dc0bc2
--- /dev/null
+++ b/drivers/net/can/dev/length.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
+ * Copyright (C) 2006 Andrey Volkov, Varma Electronics
+ * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>
+ */
See comment below ...
+
+#include <linux/can/dev.h>
+
+/* CAN DLC to real data length conversion helpers */
+
+static const u8 dlc2len[] = {0, 1, 2, 3, 4, 5, 6, 7,
+ 8, 12, 16, 20, 24, 32, 48, 64};
+
+/* get data length from raw data length code (DLC) */
+u8 can_fd_dlc2len(u8 dlc)
+{
+ return dlc2len[dlc & 0x0F];
+}
+EXPORT_SYMBOL_GPL(can_fd_dlc2len);
+
+static const u8 len2dlc[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, /* 0 - 8 */
+ 9, 9, 9, 9, /* 9 - 12 */
+ 10, 10, 10, 10, /* 13 - 16 */
+ 11, 11, 11, 11, /* 17 - 20 */
+ 12, 12, 12, 12, /* 21 - 24 */
+ 13, 13, 13, 13, 13, 13, 13, 13, /* 25 - 32 */
+ 14, 14, 14, 14, 14, 14, 14, 14, /* 33 - 40 */
+ 14, 14, 14, 14, 14, 14, 14, 14, /* 41 - 48 */
+ 15, 15, 15, 15, 15, 15, 15, 15, /* 49 - 56 */
+ 15, 15, 15, 15, 15, 15, 15, 15}; /* 57 - 64 */
+
+/* map the sanitized data length to an appropriate data length code */
+u8 can_fd_len2dlc(u8 len)
+{
+ if (unlikely(len > 64))
+ return 0xF;
+
+ return len2dlc[len];
+}
+EXPORT_SYMBOL_GPL(can_fd_len2dlc);
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 054c3bed190b..d75fba1d030a 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -18,6 +18,7 @@
#include <linux/can/bittiming.h>
#include <linux/can/error.h>
#include <linux/can/led.h>
+#include <linux/can/length.h>
#include <linux/can/netlink.h>
#include <linux/can/skb.h>
#include <linux/netdevice.h>
@@ -83,15 +84,6 @@ struct can_priv {
(..)
diff --git a/include/linux/can/length.h b/include/linux/can/length.h
new file mode 100644
index 000000000000..fabd93bcde3e
--- /dev/null
+++ b/include/linux/can/length.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2006 Andrey Volkov <avolkov@xxxxxxxxxxxx>
+ * Varma Electronics Oy
+ * Copyright (C) 2008 Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>
The CAN FD and len8_dlc length stuff was completely contributed by myself.
So if this code is now moved to a separate file the former Copyrights
should be replaced with
Copyright (C) 2020 Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
;-)
Best,
Oliver
+ */
+
+#ifndef _CAN_LENGTH_H
+#define _CAN_LENGTH_H
+
+/*
+ * 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.
+ *
+ * To be used in the CAN netdriver receive path to ensure conformance with
+ * ISO 11898-1 Chapter 8.4.2.3 (DLC field)
+ */
+#define can_cc_dlc2len(dlc) (min_t(u8, (dlc), CAN_MAX_DLEN))
+
+/* helper to get the data length code (DLC) for Classical CAN raw DLC access */
+static inline u8 can_get_cc_dlc(const struct can_frame *cf, const u32 ctrlmode)
+{
+ /* return len8_dlc as dlc value only if all conditions apply */
+ if ((ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC) &&
+ (cf->len == CAN_MAX_DLEN) &&
+ (cf->len8_dlc > CAN_MAX_DLEN && cf->len8_dlc <= CAN_MAX_RAW_DLC))
+ return cf->len8_dlc;
+
+ /* return the payload length as dlc value */
+ return cf->len;
+}
+
+/* helper to set len and len8_dlc value for Classical CAN raw DLC access */
+static inline void can_frame_set_cc_len(struct can_frame *cf, const u8 dlc,
+ const u32 ctrlmode)
+{
+ /* the caller already ensured that dlc is a value from 0 .. 15 */
+ if (ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC && dlc > CAN_MAX_DLEN)
+ cf->len8_dlc = dlc;
+
+ /* limit the payload length 'len' to CAN_MAX_DLEN */
+ cf->len = can_cc_dlc2len(dlc);
+}
+
+/* get data length from raw data length code (DLC) */
+u8 can_fd_dlc2len(u8 dlc);
+
+/* map the sanitized data length to an appropriate data length code */
+u8 can_fd_len2dlc(u8 len);
+
+#endif /* !_CAN_LENGTH_H */
