[PATCH v2 2/3] can: m_can: m_can_chip_config(): enable and configure internal timestamps
From: Torin Cooper-Bennun <hidden>
Date: 2021-03-08 10:29:58
Subsystem:
can network drivers, mcan device driver, the rest · Maintainers:
Marc Kleine-Budde, Vincent Mailhol, Markus Schneider-Pargmann, Linus Torvalds
This is a prerequisite for transitioning the m_can driver to rx-offload, which works best with TX and RX timestamps. The timestamps provided by M_CAN are 16-bit, timed according to the nominal bit timing, and may be prescaled by a multiplier up to 16. We choose the highest prescalar so that the timestamp wraps every 2^20 bit times, or 209 ms at a bus speed of 5 Mbit/s. Timestamps will have a precision of 16 bit times. Signed-off-by: Torin Cooper-Bennun <redacted> --- drivers/net/can/m_can/m_can.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index ce1fef95d34b..e61b7e186d80 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c@@ -1138,6 +1138,7 @@ static int m_can_set_bittiming(struct net_device *dev) * - >= v3.1.x: TX FIFO is used * - configure mode * - setup bittiming + * - configure timestamp generation */ static void m_can_chip_config(struct net_device *dev) {
@@ -1249,6 +1250,10 @@ static void m_can_chip_config(struct net_device *dev) /* set bittiming params */ m_can_set_bittiming(dev); + /* enable internal timestamp generation, with a prescalar of 16. The + * prescalar is applied to the nominal bit timing */ + m_can_write(cdev, M_CAN_TSCC, FIELD_PREP(TSCC_TCP_MASK, 0xf)); + m_can_config_endisable(cdev, false); if (cdev->ops->init)
--
2.30.1