Merge tag 'linux-can-next-for-5.17-20220108' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next

Marc Kleine-Budde says:

====================
pull-request: can-next 2022-01-08

this is a pull request of 22 patches for net-next/master.

The first patch is by Tom Rix and fixes an uninitialized variable in
the janz-ican3 driver (introduced in linux-can-next-for-5.17-20220105).

The next 13 patches are by my and target the mcp251xfd driver. First
several cleanup patches, then the driver is prepared for the upcoming
ethtool ring parameter and IRQ coalescing support, which is added in a
later pull request.

The remaining 8 patches are by Dario Binacchi and me and enhance the
flexcan driver. The driver is moved into a sub directory. An ethtool
private flag is added to optionally disable CAN RTR frame reception,
to make use of more RX buffers. The resulting RX buffer configuration
can be read by ethtool ring parameter support. Finally documentation
for the ethtool private flag is added to the
Documentation/networking/device_drivers/can directory.
====================

Signed-off-by: David S. Miller <[email protected]>

Author: davem330

Documentation/networking/device_drivers/can/freescale/flexcan.rst

@@ -0,0 +1,54 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+=============================
+Flexcan CAN Controller driver
+=============================
+
+Authors: Marc Kleine-Budde <[email protected]>,
+Dario Binacchi <[email protected]>
+
+On/off RTR frames reception
+===========================
+
+For most flexcan IP cores the driver supports 2 RX modes:
+
+- FIFO
+- mailbox
+
+The older flexcan cores (integrated into the i.MX25, i.MX28, i.MX35
+and i.MX53 SOCs) only receive RTR frames if the controller is
+configured for RX-FIFO mode.
+
+The RX FIFO mode uses a hardware FIFO with a depth of 6 CAN frames,
+while the mailbox mode uses a software FIFO with a depth of up to 62
+CAN frames. With the help of the bigger buffer, the mailbox mode
+performs better under high system load situations.
+
+As reception of RTR frames is part of the CAN standard, all flexcan
+cores come up in a mode where RTR reception is possible.
+
+With the "rx-rtr" private flag the ability to receive RTR frames can
+be waived at the expense of losing the ability to receive RTR
+messages. This trade off is beneficial in certain use cases.
+
+"rx-rtr" on
+  Receive RTR frames. (default)
+
+  The CAN controller can and will receive RTR frames.
+
+  On some IP cores the controller cannot receive RTR frames in the
+  more performant "RX mailbox" mode and will use "RX FIFO" mode
+  instead.
+
+"rx-rtr" off
+
+  Waive ability to receive RTR frames. (not supported on all IP cores)
+
+  This mode activates the "RX mailbox mode" for better performance, on
+  some IP cores RTR frames cannot be received anymore.
+
+The setting can only be changed if the interface is down::
+
+    ip link set dev can0 down
+    ethtool --set-priv-flags can0 rx-rtr {off|on}
+    ip link set dev can0 up

Documentation/networking/device_drivers/can/index.rst

@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+
+Controller Area Network (CAN) Device Drivers
+============================================
+
+Device drivers for CAN devices.
+
+Contents:
+
+.. toctree::
+   :maxdepth: 2
+
+   freescale/flexcan
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`

Documentation/networking/device_drivers/index.rst

@@ -11,6 +11,7 @@ Contents:
    appletalk/index
    atm/index
    cable/index
+   can/index
    cellular/index
    ethernet/index
    fddi/index

drivers/net/can/Makefile

@@ -16,7 +16,7 @@ obj-y				+= softing/
 obj-$(CONFIG_CAN_AT91)		+= at91_can.o
 obj-$(CONFIG_CAN_CC770)		+= cc770/
 obj-$(CONFIG_CAN_C_CAN)		+= c_can/
-obj-$(CONFIG_CAN_FLEXCAN)	+= flexcan.o
+obj-$(CONFIG_CAN_FLEXCAN)	+= flexcan/
 obj-$(CONFIG_CAN_GRCAN)		+= grcan.o
 obj-$(CONFIG_CAN_IFI_CANFD)	+= ifi_canfd/
 obj-$(CONFIG_CAN_JANZ_ICAN3)	+= janz-ican3.o

drivers/net/can/flexcan/Makefile

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_CAN_FLEXCAN) += flexcan.o
+
+flexcan-objs :=
+flexcan-objs += flexcan-core.o
+flexcan-objs += flexcan-ethtool.o