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 brings command line support to six TDC parameters which
were recently added to the kernel's CAN netlink interface in order to
implement TDC:
- IFLA_CAN_TDCV: Transmitter Delay Compensation Value
- IFLA_CAN_TDCO: Transmitter Delay Compensation Offset
- IFLA_CAN_TDCF: Transmitter Delay Compensation Filter window
- IFLA_CAN_TDCV_MAX_CONST: Transmitter Delay Compensation Value
maximum value
- IFLA_CAN_TDCO_MAX_CONST: Transmitter Delay Compensation Offset
maximum value
- IFLA_CAN_TDCF_MAX_CONST: Transmitter Delay Compensation Filter
window maximum value
Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
---
include/uapi/linux/can/netlink.h | 6 ++++
ip/iplink_can.c | 58 ++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+)
diff --git a/include/uapi/linux/can/netlink.h b/include/uapi/linux/can/netlink.h
index 00c763df..b85d5248 100644
--- a/include/uapi/linux/can/netlink.h
+++ b/include/uapi/linux/can/netlink.h
@@ -134,6 +134,12 @@ enum {
IFLA_CAN_BITRATE_CONST,
IFLA_CAN_DATA_BITRATE_CONST,
IFLA_CAN_BITRATE_MAX,
+ IFLA_CAN_TDCV,
+ IFLA_CAN_TDCO,
+ IFLA_CAN_TDCF,
+ IFLA_CAN_TDCV_MAX_CONST,
+ IFLA_CAN_TDCO_MAX_CONST,
+ IFLA_CAN_TDCF_MAX_CONST,
__IFLA_CAN_MAX
};
diff --git a/ip/iplink_can.c b/ip/iplink_can.c
index 6a26f3ff..ebe46024 100644
--- a/ip/iplink_can.c
+++ b/ip/iplink_can.c
@@ -28,6 +28,7 @@ static void print_usage(FILE *f)
"\n"
"\t[ dbitrate BITRATE [ dsample-point SAMPLE-POINT] ] |\n"
"\t[ dtq TQ dprop-seg PROP_SEG dphase-seg1 PHASE-SEG1\n \t dphase-seg2 PHASE-SEG2 [ dsjw SJW ] ]\n"
+ "\t[ tdcv TDCV tdco TDCO tdcf TDCF ]\n"
"\n"
"\t[ loopback { on | off } ]\n"
"\t[ listen-only { on | off } ]\n"
@@ -52,6 +53,9 @@ static void print_usage(FILE *f)
"\t PHASE-SEG2 := { 1..8 }\n"
"\t SJW := { 1..4 }\n"
"\t RESTART-MS := { 0 | NUMBER }\n"
+ "\t TDCV := { NUMBER }\n"
+ "\t TDCO := { NUMBER }\n"
+ "\t TDCF := { NUMBER }\n"
);
}
@@ -116,6 +120,7 @@ static int can_parse_opt(struct link_util *lu, int argc, char **argv,
{
struct can_bittiming bt = {}, dbt = {};
struct can_ctrlmode cm = {0, 0};
+ __u32 tdcv = -1, tdco = -1, tdcf = -1;
while (argc > 0) {
if (matches(*argv, "bitrate") == 0) {
@@ -181,6 +186,18 @@ static int can_parse_opt(struct link_util *lu, int argc, char **argv,
NEXT_ARG();
if (get_u32(&dbt.sjw, *argv, 0))
invarg("invalid \"dsjw\" value\n", *argv);
+ } else if (matches(*argv, "tdcv") == 0) {
+ NEXT_ARG();
+ if (get_u32(&tdcv, *argv, 0))
+ invarg("invalid \"tdcv\" value\n", *argv);
+ } else if (matches(*argv, "tdco") == 0) {
+ NEXT_ARG();
+ if (get_u32(&tdco, *argv, 0))
+ invarg("invalid \"tdco\" value\n", *argv);
+ } else if (matches(*argv, "tdcf") == 0) {
+ NEXT_ARG();
+ if (get_u32(&tdcf, *argv, 0))
+ invarg("invalid \"tdcf\" value\n", *argv);
} else if (matches(*argv, "loopback") == 0) {
NEXT_ARG();
set_ctrlmode("loopback", *argv, &cm,
@@ -253,6 +270,12 @@ static int can_parse_opt(struct link_util *lu, int argc, char **argv,
addattr_l(n, 1024, IFLA_CAN_DATA_BITTIMING, &dbt, sizeof(dbt));
if (cm.mask)
addattr_l(n, 1024, IFLA_CAN_CTRLMODE, &cm, sizeof(cm));
+ if (tdcv != -1)
+ addattr32(n, 1024, IFLA_CAN_TDCV, tdcv);
+ if (tdco != -1)
+ addattr32(n, 1024, IFLA_CAN_TDCO, tdco);
+ if (tdcf != -1)
+ addattr32(n, 1024, IFLA_CAN_TDCF, tdcf);
return 0;
}
@@ -523,6 +546,41 @@ static void can_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
}
}
+ if (tb[IFLA_CAN_TDCV] && tb[IFLA_CAN_TDCO] && tb[IFLA_CAN_TDCF]) {
+ __u32 *tdcv = RTA_DATA(tb[IFLA_CAN_TDCV]);
+ __u32 *tdco = RTA_DATA(tb[IFLA_CAN_TDCO]);
+ __u32 *tdcf = RTA_DATA(tb[IFLA_CAN_TDCF]);
+
+ if (is_json_context()) {
+ open_json_object("tdc");
+ print_int(PRINT_JSON, "tdcv", NULL, *tdcv);
+ print_int(PRINT_JSON, "tdco", NULL, *tdco);
+ print_int(PRINT_JSON, "tdcf", NULL, *tdcf);
+ close_json_object();
+ } else {
+ fprintf(f, "\n tdcv %d tdco %d tdcf %d",
+ *tdcv, *tdco, *tdcf);
+ }
+ }
+
+ if (tb[IFLA_CAN_TDCV_MAX_CONST] && tb[IFLA_CAN_TDCO_MAX_CONST] &&
+ tb[IFLA_CAN_TDCF_MAX_CONST]) {
+ __u32 *tdcv_max = RTA_DATA(tb[IFLA_CAN_TDCV_MAX_CONST]);
+ __u32 *tdco_max = RTA_DATA(tb[IFLA_CAN_TDCO_MAX_CONST]);
+ __u32 *tdcf_max = RTA_DATA(tb[IFLA_CAN_TDCF_MAX_CONST]);
+
+ if (is_json_context()) {
+ open_json_object("tdc_const");
+ print_int(PRINT_JSON, "tdcv_max", NULL, *tdcv_max);
+ print_int(PRINT_JSON, "tdco_max", NULL, *tdco_max);
+ print_int(PRINT_JSON, "tdcf_max", NULL, *tdcf_max);
+ close_json_object();
+ } else {
+ fprintf(f, "\n tdcv_max %d tdco_max %d tdcf_max %d",
+ *tdcv_max, *tdco_max, *tdcf_max);
+ }
+ }
+
if (tb[IFLA_CAN_TERMINATION_CONST] && tb[IFLA_CAN_TERMINATION]) {
__u16 *trm = RTA_DATA(tb[IFLA_CAN_TERMINATION]);
__u16 *trm_const = RTA_DATA(tb[IFLA_CAN_TERMINATION_CONST]);
--
2.26.2
