kernel/linux.git/include/linux/can, branch v5.15.72

can: dev: provide optional GPIO based termination support

2021-08-19T13:07:03+00:00

For CAN buses to work, a termination resistor has to be present at both ends of the bus. This resistor is usually 120 Ohms, other values may be required for special bus topologies. This patch adds support for a generic GPIO based CAN termination. The resistor value has to be specified via device tree, and it can only be attached to or detached from the bus. By default the termination is not active. Link: https://lore.kernel.org/r/20210818071232.20585-4-o.rempel@pengutronix.de Signed-off-by: Oleksij Rempel Signed-off-by: Marc Kleine-Budde

can: flexcan: add platform data header

2021-07-25T09:36:29+00:00

Add platform data header for flexcan. Link: https://lore.kernel.org/r/20210702094841.327679-1-angelo@kernel-space.org Signed-off-by: Angelo Dureghello Signed-off-by: Marc Kleine-Budde

can: bittiming: fix documentation for struct can_tdc

2021-07-25T09:36:25+00:00

This patch fixes a typo in the documentation for struct can_tdc::tdcv. The number "0" refers to automatic mode not the letter "O". Further two grammar errors in the documentation for struct can_tdc are fixed. First grammar error: add a missing third person 's'. Second grammar error: replace "such as" by "such that". The intent is to give a condition, not an example. Fixes: 289ea9e4ae59 ("can: add new CAN FD bittiming parameters: Transmitter Delay Compensation (TDC)") Link: https://lore.kernel.org/r/20210616095922.2430415-1-mkl@pengutronix.de Link: https://lore.kernel.org/r/20210616124057.60723-1-mailhol.vincent@wanadoo.fr Co-developed-by: Vincent Mailhol Signed-off-by: Vincent Mailhol Acked-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde

can: rx-offload: can_rx_offload_threaded_irq_finish(): add new function to be called from threaded interrupt

2021-07-25T09:36:25+00:00

After reading all CAN frames from the controller in the IRQ handler and storing them into a skb_queue, the driver calls napi_schedule(). In the napi poll function the skb from the skb_queue are then pushed into the networking stack. However if napi_schedule() is called from a threaded IRQ handler this triggers the following error: | NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!! To avoid this, create a new rx-offload function (can_rx_offload_threaded_irq_finish()) with a call to local_bh_disable()/local_bh_enable() around the napi_schedule() call. Convert all drivers that call can_rx_offload_irq_finish() from threaded IRQ context to can_rx_offload_threaded_irq_finish(). Link: https://lore.kernel.org/r/20210724204745.736053-4-mkl@pengutronix.de Suggested-by: Daniel Glöckner Tested-by: Oleksij Rempel Signed-off-by: Marc Kleine-Budde

can: rx-offload: can_rx_offload_irq_finish(): directly call napi_schedule()

2021-07-25T09:36:25+00:00

Instead of calling can_rx_offload_schedule() call napi_schedule() directly. As this was the last use of can_rx_offload_schedule() remove this helper function. Link: https://lore.kernel.org/r/20210724204745.736053-3-mkl@pengutronix.de Tested-by: Oleksij Rempel Signed-off-by: Marc Kleine-Budde

can: rx-offload: add skb queue for use during ISR

2021-07-25T09:36:25+00:00

Adding a skb to the skb_queue in rx-offload requires to take a lock. This commit avoids this by adding an unlocked skb queue that is appended at the end of the ISR. Having one lock at the end of the ISR should be OK as the HW is empty, not about to overflow. Link: https://lore.kernel.org/r/20210724204745.736053-2-mkl@pengutronix.de Tested-by: Oleksij Rempel Co-developed-by: Kurt Van Dijck Signed-off-by: Kurt Van Dijck Signed-off-by: Marc Kleine-Budde

can: bittiming: add CAN_KBPS, CAN_MBPS and CAN_MHZ macros

2021-03-30T09:14:45+00:00

Add three macro to simplify the readability of big bit timing numbers: - CAN_KBPS: kilobits per second (one thousand) - CAN_MBPS: megabits per second (one million) - CAN_MHZ: megahertz per second (one million) Example: u32 bitrate_max = 8 * CAN_MBPS; struct can_clock clock = {.freq = 80 * CAN_MHZ}; instead of: u32 bitrate_max = 8000000; struct can_clock clock = {.freq = 80000000}; Apply the new macro to driver/net/can/dev/bittiming.c. Link: https://lore.kernel.org/r/20210306054040.76483-1-mailhol.vincent@wanadoo.fr Signed-off-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde

can: bittiming: add calculation for CAN FD Transmitter Delay Compensation (TDC)

2021-03-30T09:14:45+00:00

The logic for the tdco calculation is to just reuse the normal sample point: tdco = sp. Because the sample point is expressed in tenth of percent and the tdco is expressed in time quanta, a conversion is needed. At the end, ssp = tdcv + tdco = tdcv + sp. Another popular method is to set tdco to the middle of the bit: tdc->tdco = can_bit_time(dbt) / 2 During benchmark tests, we could not find a clear advantages for one of the two methods. The tdco calculation is triggered each time the data_bittiming is changed so that users relying on automated calculation can use the netlink interface the exact same way without need of new parameters. For example, a command such as: ip link set canX type can bitrate 500000 dbitrate 4000000 fd on would trigger the calculation. The user using CONFIG_CAN_CALC_BITTIMING who does not want automated calculation needs to manually set tdco to zero. For example with: ip link set canX type can tdco 0 bitrate 500000 dbitrate 4000000 fd on (if the tdco parameter is provided in a previous command, it will be overwritten). If tdcv is set to zero (default), it is automatically calculated by the transiver for each frame. As such, there is no code in the kernel to calculate it. tdcf has no automated calculation functions because we could not figure out a formula for this parameter. Link: https://lore.kernel.org/r/20210224002008.4158-6-mailhol.vincent@wanadoo.fr Signed-off-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde

can: dev: reorder struct can_priv members for better packing

2021-03-30T09:14:44+00:00

Save eight bytes of holes on x86-64 architectures by reordering struct can_priv members. Before: $ pahole -C can_priv drivers/net/can/dev/dev.o struct can_priv { struct net_device * dev; /* 0 8 */ struct can_device_stats can_stats; /* 8 24 */ struct can_bittiming bittiming; /* 32 32 */ /* --- cacheline 1 boundary (64 bytes) --- */ struct can_bittiming data_bittiming; /* 64 32 */ const struct can_bittiming_const * bittiming_const; /* 96 8 */ const struct can_bittiming_const * data_bittiming_const; /* 104 8 */ struct can_tdc tdc; /* 112 12 */ /* XXX 4 bytes hole, try to pack */ /* --- cacheline 2 boundary (128 bytes) --- */ const struct can_tdc_const * tdc_const; /* 128 8 */ const u16 * termination_const; /* 136 8 */ unsigned int termination_const_cnt; /* 144 4 */ u16 termination; /* 148 2 */ /* XXX 2 bytes hole, try to pack */ const u32 * bitrate_const; /* 152 8 */ unsigned int bitrate_const_cnt; /* 160 4 */ /* XXX 4 bytes hole, try to pack */ const u32 * data_bitrate_const; /* 168 8 */ unsigned int data_bitrate_const_cnt; /* 176 4 */ u32 bitrate_max; /* 180 4 */ struct can_clock clock; /* 184 4 */ enum can_state state; /* 188 4 */ /* --- cacheline 3 boundary (192 bytes) --- */ u32 ctrlmode; /* 192 4 */ u32 ctrlmode_supported; /* 196 4 */ u32 ctrlmode_static; /* 200 4 */ int restart_ms; /* 204 4 */ struct delayed_work restart_work; /* 208 168 */ /* XXX last struct has 4 bytes of padding */ /* --- cacheline 5 boundary (320 bytes) was 56 bytes ago --- */ int (*do_set_bittiming)(struct net_device *); /* 376 8 */ /* --- cacheline 6 boundary (384 bytes) --- */ int (*do_set_data_bittiming)(struct net_device *); /* 384 8 */ int (*do_set_mode)(struct net_device *, enum can_mode); /* 392 8 */ int (*do_set_termination)(struct net_device *, u16); /* 400 8 */ int (*do_get_state)(const struct net_device *, enum can_state *); /* 408 8 */ int (*do_get_berr_counter)(const struct net_device *, struct can_berr_counter *); /* 416 8 */ unsigned int echo_skb_max; /* 424 4 */ /* XXX 4 bytes hole, try to pack */ struct sk_buff * * echo_skb; /* 432 8 */ /* size: 440, cachelines: 7, members: 31 */ /* sum members: 426, holes: 4, sum holes: 14 */ /* paddings: 1, sum paddings: 4 */ /* last cacheline: 56 bytes */ }; After: $ pahole -C can_priv drivers/net/can/dev/dev.o struct can_priv { struct net_device * dev; /* 0 8 */ struct can_device_stats can_stats; /* 8 24 */ const struct can_bittiming_const * bittiming_const; /* 32 8 */ const struct can_bittiming_const * data_bittiming_const; /* 40 8 */ struct can_bittiming bittiming; /* 48 32 */ /* --- cacheline 1 boundary (64 bytes) was 16 bytes ago --- */ struct can_bittiming data_bittiming; /* 80 32 */ const struct can_tdc_const * tdc_const; /* 112 8 */ struct can_tdc tdc; /* 120 12 */ /* --- cacheline 2 boundary (128 bytes) was 4 bytes ago --- */ unsigned int bitrate_const_cnt; /* 132 4 */ const u32 * bitrate_const; /* 136 8 */ const u32 * data_bitrate_const; /* 144 8 */ unsigned int data_bitrate_const_cnt; /* 152 4 */ u32 bitrate_max; /* 156 4 */ struct can_clock clock; /* 160 4 */ unsigned int termination_const_cnt; /* 164 4 */ const u16 * termination_const; /* 168 8 */ u16 termination; /* 176 2 */ /* XXX 2 bytes hole, try to pack */ enum can_state state; /* 180 4 */ u32 ctrlmode; /* 184 4 */ u32 ctrlmode_supported; /* 188 4 */ /* --- cacheline 3 boundary (192 bytes) --- */ u32 ctrlmode_static; /* 192 4 */ int restart_ms; /* 196 4 */ struct delayed_work restart_work; /* 200 168 */ /* XXX last struct has 4 bytes of padding */ /* --- cacheline 5 boundary (320 bytes) was 48 bytes ago --- */ int (*do_set_bittiming)(struct net_device *); /* 368 8 */ int (*do_set_data_bittiming)(struct net_device *); /* 376 8 */ /* --- cacheline 6 boundary (384 bytes) --- */ int (*do_set_mode)(struct net_device *, enum can_mode); /* 384 8 */ int (*do_set_termination)(struct net_device *, u16); /* 392 8 */ int (*do_get_state)(const struct net_device *, enum can_state *); /* 400 8 */ int (*do_get_berr_counter)(const struct net_device *, struct can_berr_counter *); /* 408 8 */ unsigned int echo_skb_max; /* 416 4 */ /* XXX 4 bytes hole, try to pack */ struct sk_buff * * echo_skb; /* 424 8 */ /* size: 432, cachelines: 7, members: 31 */ /* sum members: 426, holes: 2, sum holes: 6 */ /* paddings: 1, sum paddings: 4 */ /* last cacheline: 48 bytes */ }; Link: https://lore.kernel.org/r/20210224002008.4158-3-mailhol.vincent@wanadoo.fr Signed-off-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde

can: add new CAN FD bittiming parameters: Transmitter Delay Compensation (TDC)

2021-03-30T09:14:44+00:00

At high bit rates, the propagation delay from the TX pin to the RX pin of the transceiver causes measurement errors: the sample point on the RX pin might occur on the previous bit. This issue is addressed in ISO 11898-1 section 11.3.3 "Transmitter delay compensation" (TDC). This patch adds two new structures: can_tdc and can_tdc_const in order to implement this TDC. The structures are then added to can_priv. A controller supports TDC if an only if can_priv::tdc_const is not NULL. TDC is active if and only if: - fd flag is on - can_priv::tdc.tdco is not zero. It is the driver responsibility to check those two conditions are met. No new controller modes are introduced (i.e. no CAN_CTRL_MODE_TDC) in order not to be redundant with above logic. The names of the parameters are chosen to match existing CAN controllers specification. References: - Bosch C_CAN FD8: https://www.bosch-semiconductors.com/media/ip_modules/pdf_2/c_can_fd8/users_manual_c_can_fd8_r210_1.pdf - Microchip CAN FD Controller Module: http://ww1.microchip.com/downloads/en/DeviceDoc/MCP251XXFD-CAN-FD-Controller-Module-Family-Reference-Manual-20005678B.pdf - SAM E701/S70/V70/V71 Family: https://www.mouser.com/datasheet/2/268/60001527A-1284321.pdf Link: https://lore.kernel.org/r/20210224002008.4158-2-mailhol.vincent@wanadoo.fr Signed-off-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde