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[net-next,19/39] can: m_can: m_can_chip_config(): enable and configure internal timestamps

Message ID 20210330114559.1114855-20-mkl@pengutronix.de (mailing list archive)
State Accepted
Commit df06fd678260bca919ea894281ec54ce10e45ce6
Delegated to: Netdev Maintainers
Headers show
Series [net-next,01/39] MAINTAINERS: remove Dan Murphy from m_can and tcan4x5x | expand

Checks

Context Check Description
netdev/cover_letter success Pull request
netdev/fixes_present success Link
netdev/patch_count warning Series longer than 15 patches
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 2 maintainers not CCed: wg@grandegger.com rcsekar@samsung.com
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch warning WARNING: Block comments use a trailing */ on a separate line
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/header_inline success Link

Commit Message

Marc Kleine-Budde March 30, 2021, 11:45 a.m. UTC 
From: Torin Cooper-Bennun <torin@maxiluxsystems.com>

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.

Link: https://lore.kernel.org/r/20210308102427.63916-3-torin@maxiluxsystems.com
Signed-off-by: Torin Cooper-Bennun <torin@maxiluxsystems.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/m_can/m_can.c | 5 +++++
 1 file changed, 5 insertions(+)
diff mbox series

Patch

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 9f7cfe91f7ff..7df81e38b043 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1135,6 +1135,7 @@  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)
 {
@@ -1246,6 +1247,10 @@  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)