sys/can: model in kconfig

[aabadie]

Contribution description

To get the same modules loaded with and without TEST_KCONFIG, I had to fix a few dependencies with the gnrc_pktbuf shell command and STM32 periph_can.

Since conn_can has a dependency to gnrc_pkt, some modules are defined in the can Kconfig file. They should be removed once GNRC is fully migrated to Kconfig (some files already exists but seem to use an absolete strategy).

Testing procedure

• Green CI

Issues/PRs references

Tick one item in #16875

[riot-ci]

Murdock results

✔️ PASSED

048cc4e sys/can: remove unused module can_raw

Success	Failures	Total	Runtime
6933	0	6933	16m:54s

Artifacts

• Documentation preview

[MrKevinWeiss]

Since conn_can has a dependency to gnrc_pkt,

Is that actually what we want? It would seem this is only due to

int conn_can_isotp_recv(conn_can_isotp_t *conn, void *buf, size_t size, uint32_t timeout)
{
    assert(conn != NULL);
    assert(buf != NULL);

    int ret = 0;
    gnrc_pktsnip_t *snip;

    if (!conn->bound) {
        return -ENOTCONN;
    }

gnrc_pktsnip_t, maybe we can better isolate it? I feel like these low level things should be as isolated as possible and will help with the overall dependency modeling.

[MrKevinWeiss]

unless this gnrc_pkt is a completely self contained utility...

[aabadie]

Is that actually what we want? It would seem this is only due to

Not only, there's also

RIOT/sys/include/can/isotp.h

Lines 92 to 99 in e690ef4

	struct tpcon {
	unsigned idx; /**< current index in @p buf */
	uint8_t state; /**< the protocol state */
	uint8_t bs; /**< block size */
	uint8_t sn; /**< current sequence number */
	int tx_handle; /**< handle of the last sent frame */
	gnrc_pktsnip_t *snip; /**< allocated snip containing data buffer */
	};

[aabadie]

unless this gnrc_pkt is a completely self contained utility

It is used in many places. In the CAN code, the static implementation of gnrc_pktbuf is used and in other places the malloc implementation of gnrc_pktbuf is used. This PR only covers the static implementation and the dependency resolution is done in the CAN Kconfig file (with a TODO comment to tell to move it to gnrc once it's adapted to Kconfig)

[aabadie]

no longer needed