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can: flexcan: add Transceiver Delay Compensation support

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The CAN-FD protocol allows the transmission and reception of data at a
higher bit rate than the nominal rate used in the arbitration phase when
the message's BRS bit is set.

The TDC mechanism is effective only during the data phase of FD frames
having BRS bit set. It has no effect either on non-FD frames, or on FD
frames transmitted at normal bit rate.

Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Link: https://lore.kernel.org/r/20190712075926.7357-7-qiangqing.zhang@nxp.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Joakim Zhang 2019-07-12 08:02:56 +00:00 committed by Marc Kleine-Budde
parent 0542920c3f
commit ef5f631208
1 changed files with 19 additions and 2 deletions
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21
drivers/net/can/flexcan.c
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@ -156,6 +156,10 @@
#define FLEXCAN_FDCTRL_MBDSR_12 0x1
#define FLEXCAN_FDCTRL_MBDSR_32 0x2
#define FLEXCAN_FDCTRL_MBDSR_64 0x3
#define FLEXCAN_FDCTRL_TDCEN BIT(15)
#define FLEXCAN_FDCTRL_TDCFAIL BIT(14)
#define FLEXCAN_FDCTRL_TDCOFF GENMASK(12, 8)
#define FLEXCAN_FDCTRL_TDCVAL GENMASK(5, 0)
/* FLEXCAN FD Bit Timing register (FDCBT) bits */
#define FLEXCAN_FDCBT_FPRESDIV_MASK GENMASK(29, 20)
@ -1220,11 +1224,24 @@ static void flexcan_set_bittiming_cbt(const struct net_device *dev)
/* FDCTRL */
reg_fdctrl = priv->read(&regs->fdctrl);
reg_fdctrl &= ~FLEXCAN_FDCTRL_FDRATE;
reg_fdctrl &= ~(FLEXCAN_FDCTRL_FDRATE |
FIELD_PREP(FLEXCAN_FDCTRL_TDCOFF, 0x1f));
if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
reg_fdctrl |= FLEXCAN_FDCTRL_FDRATE;
if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK) {
/* TDC must be disabled for Loop Back mode */
reg_fdctrl &= ~FLEXCAN_FDCTRL_TDCEN;
} else {
reg_fdctrl |= FLEXCAN_FDCTRL_TDCEN |
FIELD_PREP(FLEXCAN_FDCTRL_TDCOFF,
((dbt->phase_seg1 - 1) +
dbt->prop_seg + 2) *
((dbt->brp - 1 ) + 1));
}
}
netdev_dbg(dev, "writing fdctrl=0x%08x\n", reg_fdctrl);
priv->write(reg_fdctrl, &regs->fdctrl);