can: can327: CAN/ldisc driver for ELM327 based OBD-II adapters

This is the can327 driver. It does a surprisingly good job at turning
ELM327 based OBD-II interfaces into cheap CAN interfaces for simple
homebrew projects.

Please see the included documentation for details and limitations:
Documentation/networking/device_drivers/can/can327.rst

Link: https://lore.kernel.org/all/20220618195031.10975-1-max@enpas.orgSigned-off-by: Max Staudt <max@enpas.org>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
[mkl: minor coding style improvements]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Documentation/networking/device_drivers/can/index.rst

@@ -10,6 +10,7 @@ Contents:
 .. toctree::
    :maxdepth: 2
 
+   can327
    ctu/ctucanfd-driver
    freescale/flexcan
 

MAINTAINERS

@@ -7315,6 +7315,13 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 F:	drivers/net/ethernet/ibm/ehea/
 
+ELM327 CAN NETWORK DRIVER
+M:	Max Staudt <max@enpas.org>
+L:	linux-can@vger.kernel.org
+S:	Maintained
+F:	Documentation/networking/device_drivers/can/can327.rst
+F:	drivers/net/can/can327.c
+
 EM28XX VIDEO4LINUX DRIVER
 M:	Mauro Carvalho Chehab <mchehab@kernel.org>
 L:	linux-media@vger.kernel.org

drivers/net/can/Kconfig

@@ -113,6 +113,24 @@ config CAN_AT91
 	  This is a driver for the SoC CAN controller in Atmel's AT91SAM9263
 	  and AT91SAM9X5 processors.
 
+config CAN_CAN327
+	tristate "Serial / USB serial ELM327 based OBD-II Interfaces (can327)"
+	depends on TTY
+	select CAN_RX_OFFLOAD
+	help
+	  CAN driver for several 'low cost' OBD-II interfaces based on the
+	  ELM327 OBD-II interpreter chip.
+
+	  This is a best effort driver - the ELM327 interface was never
+	  designed to be used as a standalone CAN interface. However, it can
+	  still be used for simple request-response protocols (such as OBD II),
+	  and to monitor broadcast messages on a bus (such as in a vehicle).
+
+	  Please refer to the documentation for information on how to use it:
+	  Documentation/networking/device_drivers/can/can327.rst
+
+	  If this driver is built as a module, it will be called can327.
+
 config CAN_FLEXCAN
 	tristate "Support for Freescale FLEXCAN based chips"
 	depends on OF || COLDFIRE || COMPILE_TEST

drivers/net/can/Makefile

@@ -14,6 +14,7 @@ obj-y				+= usb/
 obj-y				+= softing/
 
 obj-$(CONFIG_CAN_AT91)		+= at91_can.o
+obj-$(CONFIG_CAN_CAN327)	+= can327.o
 obj-$(CONFIG_CAN_CC770)		+= cc770/
 obj-$(CONFIG_CAN_C_CAN)		+= c_can/
 obj-$(CONFIG_CAN_CTUCANFD)	+= ctucanfd/