From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> 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: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20201119084921.2621-1-socketcan@xxxxxxxxxxxx Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> --- include/uapi/linux/can/gw.h | 4 +- net/can/gw.c | 78 +++++++++++++++++++++++++++++++++---- 2 files changed, 72 insertions(+), 10 deletions(-) diff --git a/include/uapi/linux/can/gw.h b/include/uapi/linux/can/gw.h index c2190bbe21d8..e4f0957554f3 100644 --- a/include/uapi/linux/can/gw.h +++ b/include/uapi/linux/can/gw.h @@ -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 */ diff --git a/net/can/gw.c b/net/can/gw.c index de5e8859ec9b..8598d9da0e5f 100644 --- a/net/can/gw.c +++ b/net/can/gw.c @@ -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; -- 2.29.2
