Merge tag 'linux-can-next-for-5.14-20210527' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next

Marc Kleine-Budde says:

====================
can-next 2021-05-27

The first 2 patches are by Geert Uytterhoeven and convert the rcan_can
and rcan_canfd device tree bindings to yaml.

The next 2 patches are by Oliver Hartkopp and me and update the CAN
uapi headers.

zuoqilin's patch removes an unnecessary variable from the CAN proc
code.

Patrick Menschel contributes 3 patches for CAN ISOTP to enhance the
error messages.

Jiapeng Chong's patch removes two dead stores from the softing driver.

The next 4 patches are by me and silence several warnings found by
clang compiler.

Jimmy Assarsson's patches for the kvaser_usb driver add support for
the Kvaser hydra devices.

Dario Binacchi provides 2 patches for the c_can driver, first removing
an unused variable, then adding basic ethtool support to query driver
and ring parameter info.

The last 4 patches are by Torin Cooper-Bennun and clean up the m_can
driver.

* tag 'linux-can-next-for-5.14-20210527' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next: (21 commits)
  can: m_can: fix whitespace in a few comments
  can: m_can: make TXESC, RXESC config more explicit
  can: m_can: clean up CCCR reg defs, order by revs
  can: m_can: use bits.h macros for all regmasks
  can: c_can: add ethtool support
  can: c_can: remove unused variable struct c_can_priv::rxmasked
  can: kvaser_usb: Add new Kvaser hydra devices
  can: kvaser_usb: Rename define USB_HYBRID_{,PRO_}CANLIN_PRODUCT_ID
  can: at91_can: silence clang warning
  can: mcp251xfd: silence clang warning
  can: mcp251x: mcp251x_can_probe(): silence clang warning
  can: hi311x: hi3110_can_probe(): silence clang warning
  can: softing: Remove redundant variable ptr
  can: isotp: Add error message if txqueuelen is too small
  can: isotp: add symbolic error message to isotp_module_init()
  can: isotp: change error format from decimal to symbolic error names
  can: proc: remove unnecessary variables
  can: uapi: introduce CANFD_FDF flag for mixed content in struct canfd_frame
  can: uapi: update CAN-FD frame description
  dt-bindings: can: rcar_canfd: Convert to json-schema
  ...
====================

Link: https://lore.kernel.org/r/20210527084532.1384031-1-mkl@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/include/uapi/linux/can.h b/include/uapi/linux/can.h
index c7535352fef6..90801ada2bbe 100644
--- a/include/uapi/linux/can.h
+++ b/include/uapi/linux/can.h
@@ -123,8 +123,8 @@ struct can_frame {
 /*
  * defined bits for canfd_frame.flags
  *
- * The use of struct canfd_frame implies the Extended Data Length (EDL) bit to
- * be set in the CAN frame bitstream on the wire. The EDL bit switch turns
+ * The use of struct canfd_frame implies the FD Frame (FDF) bit to
+ * be set in the CAN frame bitstream on the wire. The FDF bit switch turns
  * the CAN controllers bitstream processor into the CAN FD mode which creates
  * two new options within the CAN FD frame specification:
  *
@@ -135,9 +135,18 @@ struct can_frame {
  * controller only the CANFD_BRS bit is relevant for real CAN controllers when
  * building a CAN FD frame for transmission. Setting the CANFD_ESI bit can make
  * sense for virtual CAN interfaces to test applications with echoed frames.
+ *
+ * The struct can_frame and struct canfd_frame intentionally share the same
+ * layout to be able to write CAN frame content into a CAN FD frame structure.
+ * When this is done the former differentiation via CAN_MTU / CANFD_MTU gets
+ * lost. CANFD_FDF allows programmers to mark CAN FD frames in the case of
+ * using struct canfd_frame for mixed CAN / CAN FD content (dual use).
+ * N.B. the Kernel APIs do NOT provide mixed CAN / CAN FD content inside of
+ * struct canfd_frame therefore the CANFD_FDF flag is disregarded by Linux.
  */
 #define CANFD_BRS 0x01 /* bit rate switch (second bitrate for payload data) */
 #define CANFD_ESI 0x02 /* error state indicator of the transmitting node */
+#define CANFD_FDF 0x04 /* mark CAN FD for dual use of struct canfd_frame */
 
 /**
  * struct canfd_frame - CAN flexible data rate frame structure