[RFC PATCH v4 0/5] can: bxcan: add support for ST bxCAN controller

* [RFC PATCH v4 0/5] can: bxcan: add support for ST bxCAN controller
@ 2022-09-25 17:52 ` Dario Binacchi
  0 siblings, 0 replies; 16+ messages in thread
From: Dario Binacchi @ 2022-09-25 17:52 UTC (permalink / raw)
  To: linux-kernel
  Cc: Rob Herring, Krzysztof Kozlowski, Marc Kleine-Budde,
	Vincent Mailhol, michael, Amarula patchwork, Alexandre Torgue,
	Dario Binacchi, Christophe Roullier, David S. Miller,
	Eric Dumazet, Jakub Kicinski, Krzysztof Kozlowski, Lee Jones,
	Mathieu Poirier, Maxime Coquelin, Paolo Abeni, Patrice Chotard,
	Rob Herring, Wolfgang Grandegger, devicetree, linux-arm-kernel,
	linux-can, linux-stm32, netdev

The series adds support for the basic extended CAN controller (bxCAN)
found in many low- to middle-end STM32 SoCs.

The driver design (one core module and one driver module) was inspired
by other ST drivers (e. g. drivers/iio/adc/stm32-adc.c,
drivers/iio/adc/stm32-adc-core.c) where device instances share resources.
The shared resources functions are implemented in the core module, the
device driver in a separate module.

The driver has been tested on the stm32f469i-discovery board with a
kernel version 5.19.0-rc2 in loopback + silent mode:

ip link set can0 type can bitrate 125000 loopback on listen-only on
ip link set up can0
candump can0 -L &
cansend can0 300#AC.AB.AD.AE.75.49.AD.D1

For uboot and kernel compilation, as well as for rootfs creation I used
buildroot:

make stm32f469_disco_sd_defconfig
make

but I had to patch can-utils and busybox as can-utils and iproute are
not compiled for MMU-less microcotrollers. In the case of can-utils,
replacing the calls to fork() with vfork(), I was able to compile the
package with working candump and cansend applications, while in the
case of iproute, I ran into more than one problem and finally I decided
to extend busybox's ip link command for CAN-type devices. I'm still
wondering if it was really necessary, but this way I was able to test
the driver.

Changes in v4:
- Remove "st,stm32f4-bxcan-core" compatible. In this way the can nodes
 (compatible "st,stm32f4-bxcan") are no longer children of a parent
  node with compatible "st,stm32f4-bxcan-core".
- Add the "st,gcan" property (global can memory) to can nodes which
  references a "syscon" node containing the shared clock and memory
  addresses.
- Replace the node can@40006400 (compatible "st,stm32f4-bxcan-core")
  with the gcan@40006600 node ("sysnode" compatible). The gcan node
  contains clocks and memory addresses shared by the two can nodes
  of which it's no longer the parent.
- Add to can nodes the "st,gcan" property (global can memory) which
  references the gcan@40006600 node ("sysnode compatibble).
- Add "dt-bindings: arm: stm32: add compatible for syscon gcan node" patch.
- Drop the core driver. Thus bxcan-drv.c has been renamed to bxcan.c and
  moved to the drivers/net/can folder. The drivers/net/can/bxcan directory
  has therefore been removed.
- Use the regmap_*() functions to access the shared memory registers.
- Use spinlock to protect bxcan_rmw().
- Use 1 space, instead of tabs, in the macros definition.
- Drop clock ref-counting.
- Drop unused code.
- Drop the _SHIFT macros and use FIELD_GET()/FIELD_PREP() directly.
- Add BXCAN_ prefix to lec error codes.
- Add the macro BXCAN_RX_MB_NUM.
- Enable time triggered mode and use can_rx_offload().
- Use readx_poll_timeout() in function with timeouts.
- Loop from tail to head in bxcan_tx_isr().
- Check bits of tsr register instead of pkts variable in bxcan_tx_isr().
- Don't return from bxcan_handle_state_change() if skb/cf are NULL.
- Enable/disable the generation of the bus error interrupt depending
  on can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING.
- Don't return from bxcan_handle_bus_err() if skb is NULL.
- Drop statistics updating from bxcan_handle_bus_err().
- Add an empty line in front of 'return IRQ_HANDLED;'
- Rename bxcan_start() to bxcan_chip_start().
- Rename bxcan_stop() to bxcan_chip_stop().
- Disable all IRQs in bxcan_chip_stop().
- Rename bxcan_close() to bxcan_ndo_stop().
- Use writel instead of bxcan_rmw() to update the dlc register.

Changes in v3:
- Remove 'Dario Binacchi <dariobin@libero.it>' SOB.
- Add description to the parent of the two child nodes.
- Move "patterProperties:" after "properties: in top level before "required".
- Add "clocks" to the "required:" list of the child nodes.
- Remove 'Dario Binacchi <dariobin@libero.it>' SOB.
- Add "clocks" to can@0 node.
- Remove 'Dario Binacchi <dariobin@libero.it>' SOB.
- Remove a blank line.
- Remove 'Dario Binacchi <dariobin@libero.it>' SOB.
- Fix the documentation file path in the MAINTAINERS entry.
- Do not increment the "stats->rx_bytes" if the frame is remote.
- Remove pr_debug() call from bxcan_rmw().

Changes in v2:
- Change the file name into 'st,stm32-bxcan-core.yaml'.
- Rename compatibles:
  - st,stm32-bxcan-core -> st,stm32f4-bxcan-core
  - st,stm32-bxcan -> st,stm32f4-bxcan
- Rename master property to st,can-master.
- Remove the status property from the example.
- Put the node child properties as required.
- Remove a blank line.
- Fix sparse errors.
- Create a MAINTAINERS entry.
- Remove the print of the registers address.
- Remove the volatile keyword from bxcan_rmw().
- Use tx ring algorithm to manage tx mailboxes.
- Use can_{get|put}_echo_skb().
- Update DT properties.

Dario Binacchi (5):
  dt-bindings: arm: stm32: add compatible for syscon gcan node
  dt-bindings: net: can: add STM32 bxcan DT bindings
  ARM: dts: stm32: add CAN support on stm32f429
  ARM: dts: stm32: add pin map for CAN controller on stm32f4
  can: bxcan: add support for ST bxCAN controller

 .../bindings/arm/stm32/st,stm32-syscon.yaml   |    2 +
 .../bindings/net/can/st,stm32-bxcan.yaml      |   83 ++
 MAINTAINERS                                   |    7 +
 arch/arm/boot/dts/stm32f4-pinctrl.dtsi        |   30 +
 arch/arm/boot/dts/stm32f429.dtsi              |   29 +
 drivers/net/can/Kconfig                       |   12 +
 drivers/net/can/Makefile                      |    1 +
 drivers/net/can/bxcan.c                       | 1110 +++++++++++++++++
 8 files changed, 1274 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/can/st,stm32-bxcan.yaml
 create mode 100644 drivers/net/can/bxcan.c

-- 
2.32.0

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