kernel/linux.git/drivers/net/can/dev/dev.c, branch linux-6.9.y

can: dev: add can_state_get_by_berr_counter() to return the CAN state based on the current error counters

2023-10-05T19:44:48+00:00

Some CAN controllers do not have a register that contains the current CAN state, but only a register that contains the error counters. Introduce a new function can_state_get_by_berr_counter() that returns the current TX and RX state depending on the provided CAN bit error counters. Link: https://lore.kernel.org/all/20231005-at91_can-rx_offload-v2-1-9987d53600e0@pengutronix.de Signed-off-by: Marc Kleine-Budde

can: dev: can_restart(): move debug message and stats after successful restart

2023-10-05T19:33:41+00:00

Move the debug message "restarted" and the CAN restart stats_after_ the successful restart of the CAN device, because the restart may fail. While there update the error message from printing the error number to printing symbolic error names. Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-4-91b5c1fd922c@pengutronix.de Reviewed-by: Vincent Mailhol [mkl: mention stats in subject and description, too] Signed-off-by: Marc Kleine-Budde

can: dev: can_restart(): reverse logic to remove need for goto

2023-10-05T19:32:45+00:00

Reverse the logic in the if statement and eliminate the need for a goto to simplify code readability. Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-3-91b5c1fd922c@pengutronix.de Reviewed-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde

can: dev: can_restart(): fix race condition between controller restart and netif_carrier_on()

2023-10-05T19:32:26+00:00

This race condition was discovered while updating the at91_can driver to use can_bus_off(). The following scenario describes how the converted at91_can driver would behave. When a CAN device goes into BUS-OFF state, the driver usually stops/resets the CAN device and calls can_bus_off(). This function sets the netif carrier to off, and (if configured by user space) schedules a delayed work that calls can_restart() to restart the CAN device. The can_restart() function first checks if the carrier is off and triggers an error message if the carrier is OK. Then it calls the driver's do_set_mode() function to restart the device, then it sets the netif carrier to on. There is a race window between these two calls. The at91 CAN controller (observed on the sama5d3, a single core 32 bit ARM CPU) has a hardware limitation. If the device goes into bus-off while sending a CAN frame, there is no way to abort the sending of this frame. After the controller is enabled again, another attempt is made to send it. If the bus is still faulty, the device immediately goes back to the bus-off state. The driver calls can_bus_off(), the netif carrier is switched off and another can_restart is scheduled. This occurs within the race window before the original can_restart() handler marks the netif carrier as OK. This would cause the 2nd can_restart() to be called with an OK netif carrier, resulting in an error message. The flow of the 1st can_restart() looks like this: can_restart() // bail out if netif_carrier is OK netif_carrier_ok(dev) priv->do_set_mode(dev, CAN_MODE_START) // enable CAN controller // sama5d3 restarts sending old message // CAN devices goes into BUS_OFF, triggers IRQ // IRQ handler start at91_irq() at91_irq_err_line() can_bus_off() netif_carrier_off() schedule_delayed_work() // IRQ handler end netif_carrier_on() The 2nd can_restart() will be called with an OK netif carrier and the error message will be printed. To close the race window, first set the netif carrier to on, then restart the controller. In case the restart fails with an error code, roll back the netif carrier to off. Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface") Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-2-91b5c1fd922c@pengutronix.de Reviewed-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde

can: dev: can_restart(): don't crash kernel if carrier is OK

2023-10-05T19:32:12+00:00

During testing, I triggered a can_restart() with the netif carrier being OK [1]. The BUG_ON, which checks if the carrier is OK, results in a fatal kernel crash. This is neither helpful for debugging nor for a production system. [1] The root cause is a race condition in can_restart() which will be fixed in the next patch. Do not crash the kernel, issue an error message instead, and continue restarting the CAN device anyway. Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface") Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-1-91b5c1fd922c@pengutronix.de Reviewed-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde

can: dev: register_candev(): bail out if both fixed bit rates and bit timing constants are provided

2023-02-06T12:57:26+00:00

The CAN driver framework supports either fixed bit rates or bit timing constants. Bail out during driver registration if both are given. Link: https://lore.kernel.org/all/20230202110854.2318594-7-mkl@pengutronix.de Signed-off-by: Marc Kleine-Budde

can: dev: register_candev(): ensure that bittiming const are valid

2023-02-06T12:57:26+00:00

Implement the function can_bittiming_const_valid() to check the validity of the specified bit timing constant. Call this function from register_candev() to check the bit timing constants during the registration of the CAN interface. Link: https://lore.kernel.org/all/20230202110854.2318594-6-mkl@pengutronix.de Signed-off-by: Marc Kleine-Budde

can: dev: add generic function can_eth_ioctl_hwts()

2022-07-28T09:44:30+00:00

Tools based on libpcap (such as tcpdump) expect the SIOCSHWTSTAMP ioctl call to be supported. This is also specified in the kernel doc [1]. The purpose of this ioctl is to toggle the hardware timestamps. Currently, CAN devices which support hardware timestamping have those always activated. can_eth_ioctl_hwts() is a dumb function that will always succeed when requested to set tx_type to HWTSTAMP_TX_ON or rx_filter to HWTSTAMP_FILTER_ALL. [1] Kernel doc: Timestamping, section 3.1 "Hardware Timestamping Implementation: Device Drivers" Link: https://docs.kernel.org/networking/timestamping.html#hardware-timestamping-implementation-device-drivers Signed-off-by: Vincent Mailhol Link: https://lore.kernel.org/all/20220727101641.198847-9-mailhol.vincent@wanadoo.fr Signed-off-by: Marc Kleine-Budde

can: dev: add generic function can_ethtool_op_get_ts_info_hwts()

2022-07-28T09:44:30+00:00

Add function can_ethtool_op_get_ts_info_hwts(). This function will be used by CAN devices with hardware TX/RX timestamping support to implement ethtool_ops::get_ts_info. This function does not offer support to activate/deactivate hardware timestamps at device level nor support the filter options (which is currently the case for all CAN devices with hardware timestamping support). The fact that hardware timestamp can not be deactivated at hardware level does not impact the userland. As long as the user do not set SO_TIMESTAMPING using a setsockopt() or ioctl(), the kernel will not emit TX timestamps (RX timestamps will still be reproted as it is the case currently). Drivers which need more fine grained control remains free to implement their own function, but we foresee that the generic function introduced here will be sufficient for the majority. Signed-off-by: Vincent Mailhol Link: https://lore.kernel.org/all/20220727101641.198847-8-mailhol.vincent@wanadoo.fr Signed-off-by: Marc Kleine-Budde

can: Kconfig: turn menu "CAN Device Drivers" into a menuconfig using CAN_DEV

2022-06-11T15:11:01+00:00

In the next patches, the software/virtual drivers (slcan, v(x)can) will depend on drivers/net/can/dev/skb.o. This patch changes the scope of the can-dev module to include the above mentioned drivers. To do so, we reuse the menu "CAN Device Drivers" and turn it into a configmenu using the config symbol CAN_DEV (which we released in previous patch). Also, add a description to this new CAN_DEV menuconfig. The symbol CAN_DEV now only triggers the build of skb.o. For this reasons, all the macros from linux/module.h are deported from drivers/net/can/dev/dev.c to drivers/net/can/dev/skb.c. Finally, drivers/net/can/dev/Makefile is adjusted accordingly. Link: https://lore.kernel.org/all/20220610143009.323579-3-mailhol.vincent@wanadoo.fr Suggested-by: Oliver Hartkopp Signed-off-by: Vincent Mailhol Acked-by: Max Staudt Tested-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde