Commit 94c23097 authored by Oliver Hartkopp's avatar Oliver Hartkopp Committed by Marc Kleine-Budde
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can: gw: support modification of Classical CAN DLCs 



Add support for data length code modifications for Classical CAN.

The netlink configuration interface always allowed to pass any value
that fits into a byte, therefore only the modification process had to be
extended to handle the raw DLC represenation of Classical CAN frames.

When a DLC value from 0 .. F is provided for Classical CAN frame
modifications the 'len' value is modified as-is with the exception that
potentially existing 9 .. F DLC values in the len8_dlc element are moved
to the 'len' element for the modification operation by mod_retrieve_ccdlc().

After the modification the Classical CAN frame DLC information is brought
back into the correct format by mod_store_ccdlc() which is filling 'len'
and 'len8_dlc' accordingly.

Signed-off-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/r/20201119084921.2621-1-socketcan@hartkopp.net


Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 396b3ced

include/uapi/linux/can/gw.h

+2 −2
Original line number Diff line number Diff line
@@ -98,8 +98,8 @@ enum { 


/* CAN frame elements that are affected by curr. 3 CAN frame modifications */

#define CGW_MOD_ID	0x01

#define CGW_MOD_DLC	0x02		/* contains the data length in bytes */

#define CGW_MOD_LEN	CGW_MOD_DLC	/* CAN FD length representation */

#define CGW_MOD_DLC	0x02		/* Classical CAN data length code */

#define CGW_MOD_LEN	CGW_MOD_DLC	/* CAN FD (plain) data length */

#define CGW_MOD_DATA	0x04

#define CGW_MOD_FLAGS	0x08		/* CAN FD flags */

net/can/gw.c

+70 −8
Original line number Diff line number Diff line
@@ -199,6 +199,68 @@ static void mod_set_fddata(struct canfd_frame *cf, struct cf_mod *mod) 
	memcpy(cf->data, mod->modframe.set.data, CANFD_MAX_DLEN);

}



/* retrieve valid CC DLC value and store it into 'len' */

static void mod_retrieve_ccdlc(struct canfd_frame *cf)

{

	struct can_frame *ccf = (struct can_frame *)cf;



	/* len8_dlc is only valid if len == CAN_MAX_DLEN */

	if (ccf->len != CAN_MAX_DLEN)

		return;



	/* do we have a valid len8_dlc value from 9 .. 15 ? */

	if (ccf->len8_dlc > CAN_MAX_DLEN && ccf->len8_dlc <= CAN_MAX_RAW_DLC)

		ccf->len = ccf->len8_dlc;

}



/* convert valid CC DLC value in 'len' into struct can_frame elements */

static void mod_store_ccdlc(struct canfd_frame *cf)

{

	struct can_frame *ccf = (struct can_frame *)cf;



	/* clear potential leftovers */

	ccf->len8_dlc = 0;



	/* plain data length 0 .. 8 - that was easy */

	if (ccf->len <= CAN_MAX_DLEN)

		return;



	/* potentially broken values are catched in can_can_gw_rcv() */

	if (ccf->len > CAN_MAX_RAW_DLC)

		return;



	/* we have a valid dlc value from 9 .. 15 in ccf->len */

	ccf->len8_dlc = ccf->len;

	ccf->len = CAN_MAX_DLEN;

}



static void mod_and_ccdlc(struct canfd_frame *cf, struct cf_mod *mod)

{

	mod_retrieve_ccdlc(cf);

	mod_and_len(cf, mod);

	mod_store_ccdlc(cf);

}



static void mod_or_ccdlc(struct canfd_frame *cf, struct cf_mod *mod)

{

	mod_retrieve_ccdlc(cf);

	mod_or_len(cf, mod);

	mod_store_ccdlc(cf);

}



static void mod_xor_ccdlc(struct canfd_frame *cf, struct cf_mod *mod)

{

	mod_retrieve_ccdlc(cf);

	mod_xor_len(cf, mod);

	mod_store_ccdlc(cf);

}



static void mod_set_ccdlc(struct canfd_frame *cf, struct cf_mod *mod)

{

	mod_set_len(cf, mod);

	mod_store_ccdlc(cf);

}



static void canframecpy(struct canfd_frame *dst, struct can_frame *src)

{

	/* Copy the struct members separately to ensure that no uninitialized
@@ -842,8 +904,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod, 
			if (mb.modtype & CGW_MOD_ID)

				mod->modfunc[modidx++] = mod_and_id;



			if (mb.modtype & CGW_MOD_LEN)

				mod->modfunc[modidx++] = mod_and_len;

			if (mb.modtype & CGW_MOD_DLC)

				mod->modfunc[modidx++] = mod_and_ccdlc;



			if (mb.modtype & CGW_MOD_DATA)

				mod->modfunc[modidx++] = mod_and_data;
@@ -858,8 +920,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod, 
			if (mb.modtype & CGW_MOD_ID)

				mod->modfunc[modidx++] = mod_or_id;



			if (mb.modtype & CGW_MOD_LEN)

				mod->modfunc[modidx++] = mod_or_len;

			if (mb.modtype & CGW_MOD_DLC)

				mod->modfunc[modidx++] = mod_or_ccdlc;



			if (mb.modtype & CGW_MOD_DATA)

				mod->modfunc[modidx++] = mod_or_data;
@@ -874,8 +936,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod, 
			if (mb.modtype & CGW_MOD_ID)

				mod->modfunc[modidx++] = mod_xor_id;



			if (mb.modtype & CGW_MOD_LEN)

				mod->modfunc[modidx++] = mod_xor_len;

			if (mb.modtype & CGW_MOD_DLC)

				mod->modfunc[modidx++] = mod_xor_ccdlc;



			if (mb.modtype & CGW_MOD_DATA)

				mod->modfunc[modidx++] = mod_xor_data;
@@ -890,8 +952,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod, 
			if (mb.modtype & CGW_MOD_ID)

				mod->modfunc[modidx++] = mod_set_id;



			if (mb.modtype & CGW_MOD_LEN)

				mod->modfunc[modidx++] = mod_set_len;

			if (mb.modtype & CGW_MOD_DLC)

				mod->modfunc[modidx++] = mod_set_ccdlc;



			if (mb.modtype & CGW_MOD_DATA)

				mod->modfunc[modidx++] = mod_set_data;