linux-stable.git/drivers/net/can/dev, branch v6.6

can: rx-offload: add can_rx_offload_get_echo_skb_queue_tail()

2023-07-28T07:45:25+00:00

Add can_rx_offload_get_echo_skb_queue_tail(). This function addds the
echo skb at the end of rx-offload the queue. This is intended for
devices without timestamp support.

Link: https://lore.kernel.org/all/20230718-gs_usb-rx-offload-v2-2-716e542d14d5@pengutronix.de
Signed-off-by: Marc Kleine-Budde

can: rx-offload: rename rx_offload_get_echo_skb() -> can_rx_offload_get_echo_skb_queue_timestamp()

2023-07-28T07:45:24+00:00

Rename the rx_offload_get_echo_skb() function to
can_rx_offload_get_echo_skb_queue_timestamp(), since it inserts the
echo skb into the rx-offload queue sorted by timestamp.

This is a preparation for adding
can_rx_offload_get_echo_skb_queue_tail(), which adds the echo skb to
the end of the queue. This is intended for devices that do not support
timestamps.

Link: https://lore.kernel.org/all/20230718-gs_usb-rx-offload-v2-1-716e542d14d5@pengutronix.de
Signed-off-by: Marc Kleine-Budde

can: length: refactor frame lengths definition to add size in bits

2023-06-22T07:43:40+00:00

Introduce a method to calculate the exact size in bits of a CAN(-FD)
frame with or without dynamic bitstuffing.

These are all the possible combinations taken into account:

  - Classical CAN or CAN-FD
  - Standard or Extended frame format
  - CAN-FD CRC17 or CRC21
  - Include or not intermission

Instead of doing several individual macro definitions, declare the
can_frame_bits() function-like macro. To this extent, do a full
refactoring of the length definitions.

In addition add the can_frame_bytes(). This function-like macro
replaces the existing macro:

  - CAN_FRAME_OVERHEAD_SFF: can_frame_bytes(false, false, 0)
  - CAN_FRAME_OVERHEAD_EFF: can_frame_bytes(false, true, 0)
  - CANFD_FRAME_OVERHEAD_SFF: can_frame_bytes(true, false, 0)
  - CANFD_FRAME_OVERHEAD_EFF: can_frame_bytes(true, true, 0)

Function-like macros were chosen over inline functions because they
can be used to initialize const struct fields.

The different maximum frame lengths (maximum data length, including
intermission) are as follow:

   Frame type				bits	bytes
  -------------------------------------------------------
   Classic CAN SFF no bitstuffing	111	14
   Classic CAN EFF no bitstuffing	131	17
   Classic CAN SFF bitstuffing		135	17
   Classic CAN EFF bitstuffing		160	20
   CAN-FD SFF no bitstuffing		579	73
   CAN-FD EFF no bitstuffing		598	75
   CAN-FD SFF bitstuffing		712	89
   CAN-FD EFF bitstuffing		736	92

The macro CAN_FRAME_LEN_MAX and CANFD_FRAME_LEN_MAX are kept as an
alias to, respectively, can_frame_bytes(false, true, CAN_MAX_DLEN) and
can_frame_bytes(true, true, CANFD_MAX_DLEN).

In addition to the above:

 - Use ISO 11898-1:2015 definitions for the names of the CAN frame
   fields.
 - Include linux/bits.h for use of BITS_PER_BYTE.
 - Include linux/math.h for use of mult_frac() and
   DIV_ROUND_UP(). N.B: the use of DIV_ROUND_UP() is not new to this
   patch, but the include was previously omitted.
 - Add copyright 2023 for myself.

Suggested-by: Thomas Kopp 
Signed-off-by: Vincent Mailhol 
Reviewed-by: Thomas Kopp 
Link: https://lore.kernel.org/all/20230611025728.450837-4-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde

can: rx-offload: fix coding style

2023-06-22T07:42:28+00:00

This patch aligns code to match open parenthesis.

Link: https://lore.kernel.org/all/20230620131130.240180-2-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde

can: dev: fix missing CAN XL support in can_put_echo_skb()

2023-05-15T20:24:46+00:00

can_put_echo_skb() checks for the enabled IFF_ECHO flag and the
correct ETH_P type of the given skbuff. When implementing the CAN XL
support the new check for ETH_P_CANXL has been forgotten.

Fixes: fb08cba12b52 ("can: canxl: update CAN infrastructure for CAN XL frames")
Signed-off-by: Oliver Hartkopp 
Link: https://lore.kernel.org/all/20230506184515.39241-1-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde

can: bittiming: can_validate_bitrate(): report error via netlink

2023-02-06T12:57:27+00:00

Report an error to user space via netlink if the requested bit rate is
not supported by the device.

Link: https://lore.kernel.org/all/20230202110854.2318594-18-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde

can: bittiming: can_calc_bittiming(): convert from netdev_err() to NL_SET_ERR_MSG_FMT()

2023-02-06T12:57:27+00:00

Replace the netdev_err() by NL_SET_ERR_MSG_FMT() to better inform the
user about the problem. While there, use %u to print unsigned values
and improve error message a bit.

In case of an error, return -EINVAL instead of -EDOM, this corresponds
better to the actual meaning of the error value.

Link: https://lore.kernel.org/all/20230202110854.2318594-17-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde

can: bittiming: can_calc_bittiming(): clean up SJW handling

2023-02-06T12:57:27+00:00

In the current code, if the user configures a bitrate, a default SJW
value of 1 is used. If the user configures both a bitrate and a SJW
value, can_calc_bittiming() silently limits the SJW value to SJW max
and TSEG2.

We came to the conclusion that if the user provided an invalid SJW
value, it's best to bail out and inform the user [1].

[1] https://lore.kernel.org/all/CAMZ6RqKqhmTgUZiwe5uqUjBDnhhC2iOjZ791+Y845btJYwVDKg@mail.gmail.com

Further the ISO 11898-1:2015 standard mandates that "SJW shall be less
than or equal to the minimum of these two items: Phase_Seg1 and
Phase_Seg2." [2] The current code is missing that check.

[2] https://lore.kernel.org/all/BL3PR11MB64844E3FC13C55433CDD0B3DFB449@BL3PR11MB6484.namprd11.prod.outlook.com

The previous patches introduced
1) can_sjw_set_default() - sets a default value for SJW if unset
2) can_sjw_check() - implements a SJW check against SJW max, Phase
   Seg1 and Phase Seg2. In the error case this function reports the error
   to user space via netlink.

Replace both the open-coded SJW default setting and the open-coded and
insufficient checks of SJW with the helper functions
can_sjw_set_default() and can_sjw_check().

Link: https://lore.kernel.org/all/20230202110854.2318594-16-mkl@pengutronix.de
Link: https://lore.kernel.org/all/CAMZ6RqKqhmTgUZiwe5uqUjBDnhhC2iOjZ791+Y845btJYwVDKg@mail.gmail.com
Link: https://lore.kernel.org/all/BL3PR11MB64844E3FC13C55433CDD0B3DFB449@BL3PR11MB6484.namprd11.prod.outlook.com
Suggested-by: Thomas Kopp 
Suggested-by: Vincent Mailhol 
Signed-off-by: Marc Kleine-Budde

can: bittiming: can_sjw_set_default(): use Phase Seg2 / 2 as default for SJW

2023-02-06T12:57:27+00:00

"The (Re-)Synchronization Jump Width (SJW) defines how far a
 resynchronization may move the Sample Point inside the limits defined
 by the Phase Buffer Segments to compensate for edge phase errors." [1]

In other words, this means that the SJW parameter controls the
tolerance of the CAN controller to frequency errors compared to other
CAN controllers.

If the user space does not provide an SJW parameter, the kernel
chooses a default value of 1. This has proven to be a good default
value for classic CAN controllers, but no longer for modern CAN-FD
controllers.

In the past there were CAN controllers like the sja1000 with a rather
limited range of bit timing parameters. For the standard bit rates
this results in the following bit timing parameters:

| Bit timing parameters for sja1000 with 8.000000 MHz ref clock
|                     _----+--------------=> tseg1: 1 …   16
|                    /    /     _---------=> tseg2: 1 …    8
|                   |    |     /    _-----=> sjw:   1 …    4
|                   |    |    |    /    _-=> brp:   1 …   64 (inc: 1)
|                   |    |    |   |    /
|  nominal          |    |    |   |   |     real  Bitrt    nom   real   SampP
|  Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP  Bitrate  Error  SampP  SampP   Error  BTR0 BTR1
|  1000000    125   2    3    2   1   1  1000000   0.0%  75.0%  75.0%   0.0%   0x00 0x14
|   800000    125   3    4    2   1   1   800000   0.0%  80.0%  80.0%   0.0%   0x00 0x16
|   666666    125   4    4    3   1   1   666666   0.0%  80.0%  75.0%   6.2%   0x00 0x27
|   500000    125   6    7    2   1   1   500000   0.0%  87.5%  87.5%   0.0%   0x00 0x1c
|   250000    250   6    7    2   1   2   250000   0.0%  87.5%  87.5%   0.0%   0x01 0x1c
|   125000    500   6    7    2   1   4   125000   0.0%  87.5%  87.5%   0.0%   0x03 0x1c
|   100000    625   6    7    2   1   5   100000   0.0%  87.5%  87.5%   0.0%   0x04 0x1c
|    83333    750   6    7    2   1   6    83333   0.0%  87.5%  87.5%   0.0%   0x05 0x1c
|    50000   1250   6    7    2   1  10    50000   0.0%  87.5%  87.5%   0.0%   0x09 0x1c
|    33333   1875   6    7    2   1  15    33333   0.0%  87.5%  87.5%   0.0%   0x0e 0x1c
|    20000   3125   6    7    2   1  25    20000   0.0%  87.5%  87.5%   0.0%   0x18 0x1c
|    10000   6250   6    7    2   1  50    10000   0.0%  87.5%  87.5%   0.0%   0x31 0x1c

The attentive reader will notice that the SJW is 1 in most cases,
while the Seg2 phase is 2. Both values are given in TQ units, which in
turn is a duration in nanoseconds.

For example the 500 kbit/s configuration:

|  nominal                                  real  Bitrt    nom   real   SampP
|  Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP  Bitrate  Error  SampP  SampP   Error  BTR0 BTR1
|   500000    125   6    7    2   1   1   500000   0.0%  87.5%  87.5%   0.0%   0x00 0x1c

the TQ is 125ns, the Phase Seg2 is "2" (== 250ns), the SJW is "1" (==
125 ns).

Looking at a more modern CAN controller like a mcp2518fd, it has wider
bit timing registers.

| Bit timing parameters for mcp251xfd with 40.000000 MHz ref clock
|                     _----+--------------=> tseg1: 2 …  256
|                    /    /     _---------=> tseg2: 1 …  128
|                   |    |     /    _-----=> sjw:   1 …  128
|                   |    |    |    /    _-=> brp:   1 …  256 (inc: 1)
|                   |    |    |   |    /
|  nominal          |    |    |   |   |     real  Bitrt    nom   real   SampP
|  Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP  Bitrate  Error  SampP  SampP   Error      NBTCFG
|   500000     25  34   35   10   1   1   500000   0.0%  87.5%  87.5%   0.0%   0x00440900

The TQ is 25ns, the Phase Seg 2 is "10" (== 250ns), the SJW is "1" (==
25ns).

Since the kernel chooses a default SJW of 1 regardless of the TQ, this
leads to a much smaller SJW and thus much smaller tolerances to
frequency errors.

To maintain the same oscillator tolerances on controllers with wide
bit timing registers, select a default SJW value of Phase Seg2 / 2
unless Phase Seg 1 is less. This results in the following bit timing
parameters:

| Bit timing parameters for mcp251xfd with 40.000000 MHz ref clock
|                     _----+--------------=> tseg1: 2 …  256
|                    /    /     _---------=> tseg2: 1 …  128
|                   |    |     /    _-----=> sjw:   1 …  128
|                   |    |    |    /    _-=> brp:   1 …  256 (inc: 1)
|                   |    |    |   |    /
|  nominal          |    |    |   |   |     real  Bitrt    nom   real   SampP
|  Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP  Bitrate  Error  SampP  SampP   Error      NBTCFG
|   500000     25  34   35   10   5   1   500000   0.0%  87.5%  87.5%   0.0%   0x00440904

The TQ is 25ns, the Phase Seg 2 is "10" (== 250ns), the SJW is "5" (==
125ns). Which is the same as on the sja1000 controller.

[1] http://web.archive.org/http://www.oertel-halle.de/files/cia99paper.pdf

Link: https://lore.kernel.org/all/20230202110854.2318594-15-mkl@pengutronix.de
Cc: Mark Bath 
Signed-off-by: Marc Kleine-Budde

can: bittiming: can_sjw_check(): check that SJW is not longer than either Phase Buffer Segment

2023-02-06T12:57:27+00:00

According to "The Configuration of the CAN Bit Timing" [1] the SJW
"may not be longer than either Phase Buffer Segment".

Check SJW against length of both Phase buffers. In case the SJW is
greater, report an error via netlink to user space and bail out.

[1] http://web.archive.org/http://www.oertel-halle.de/files/cia99paper.pdf

Link: https://lore.kernel.org/all/20230202110854.2318594-14-mkl@pengutronix.de
Suggested-by: Vincent Mailhol 
Signed-off-by: Marc Kleine-Budde