From ce18e41400d0df18c881391d48f1bd90c00d0336 Mon Sep 17 00:00:00 2001
From: Henrik Brix Andersen <hebad@vestas.com>
Date: Fri, 8 Apr 2022 10:23:49 +0200
Subject: [PATCH] drivers: can: mcux: flexcan: only initialize the FlexCAN IP
 once

Only initialize the FlexCAN IP core once since initialzing it has the
side effect of resetting the IP core and thus clearing previous settings
such as RX filters.

Fixes: #44680

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
---
 drivers/can/can_mcux_flexcan.c | 69 +++++++++++++++++++++-------------
 1 file changed, 42 insertions(+), 27 deletions(-)

diff --git a/drivers/can/can_mcux_flexcan.c b/drivers/can/can_mcux_flexcan.c
index 23fe4916105..2df8116b17d 100644
--- a/drivers/can/can_mcux_flexcan.c
+++ b/drivers/can/can_mcux_flexcan.c
@@ -183,17 +183,11 @@ static int mcux_flexcan_set_timing(const struct device *dev,
 
 static int mcux_flexcan_set_mode(const struct device *dev, enum can_mode mode)
 {
-	struct mcux_flexcan_data *data = dev->data;
 	const struct mcux_flexcan_config *config = dev->config;
-	flexcan_config_t flexcan_config;
-	uint32_t clock_freq;
+	uint32_t ctrl1;
+	uint32_t mcr;
 	int err;
 
-	err = mcux_flexcan_get_core_clock(dev, &clock_freq);
-	if (err != 0) {
-		return -EIO;
-	}
-
 	if (config->phy != NULL) {
 		err = can_transceiver_enable(config->phy);
 		if (err != 0) {
@@ -202,31 +196,33 @@ static int mcux_flexcan_set_mode(const struct device *dev, enum can_mode mode)
 		}
 	}
 
-	FLEXCAN_GetDefaultConfig(&flexcan_config);
-	flexcan_config.maxMbNum = FSL_FEATURE_FLEXCAN_HAS_MESSAGE_BUFFER_MAX_NUMBERn(0);
-	flexcan_config.clkSrc = config->clk_source;
-	flexcan_config.baudRate = clock_freq /
-	      (1U + data->timing.prop_seg + data->timing.phase_seg1 +
-	       data->timing.phase_seg2) / data->timing.prescaler;
-	flexcan_config.enableIndividMask = true;
+	FLEXCAN_EnterFreezeMode(config->base);
 
-	flexcan_config.timingConfig.rJumpwidth = data->timing.sjw - 1U;
-	flexcan_config.timingConfig.propSeg = data->timing.prop_seg - 1U;
-	flexcan_config.timingConfig.phaseSeg1 = data->timing.phase_seg1 - 1U;
-	flexcan_config.timingConfig.phaseSeg2 = data->timing.phase_seg2 - 1U;
+	ctrl1 = config->base->CTRL1;
+	mcr = config->base->MCR;
 
 	if (mode == CAN_LOOPBACK_MODE || mode == CAN_SILENT_LOOPBACK_MODE) {
-		flexcan_config.enableLoopBack = true;
+		/* Enable loopback and self-reception */
+		ctrl1 |= CAN_CTRL1_LPB_MASK;
+		mcr &= ~(CAN_MCR_SRXDIS_MASK);
 	} else {
-		/* Disable self-reception unless loopback is requested */
-		flexcan_config.disableSelfReception = true;
+		/* Disable loopback and self-reception */
+		ctrl1 &= ~(CAN_CTRL1_LPB_MASK);
+		mcr |= CAN_MCR_SRXDIS_MASK;
 	}
 
 	if (mode == CAN_SILENT_MODE || mode == CAN_SILENT_LOOPBACK_MODE) {
-		flexcan_config.enableListenOnlyMode = true;
+		/* Enable listen-only mode */
+		ctrl1 |= CAN_CTRL1_LOM_MASK;
+	} else {
+		/* Disable listen-only mode */
+		ctrl1 &= ~(CAN_CTRL1_LOM_MASK);
 	}
 
-	FLEXCAN_Init(config->base, &flexcan_config, clock_freq);
+	config->base->CTRL1 = ctrl1;
+	config->base->MCR = mcr;
+
+	FLEXCAN_ExitFreezeMode(config->base);
 
 	return 0;
 }
@@ -691,6 +687,8 @@ static int mcux_flexcan_init(const struct device *dev)
 {
 	const struct mcux_flexcan_config *config = dev->config;
 	struct mcux_flexcan_data *data = dev->data;
+	flexcan_config_t flexcan_config;
+	uint32_t clock_freq;
 	int err;
 	int i;
 
@@ -743,13 +741,30 @@ static int mcux_flexcan_init(const struct device *dev)
 	}
 #endif
 
-	err = mcux_flexcan_set_mode(dev, CAN_NORMAL_MODE);
-	if (err) {
-		return err;
+	err = mcux_flexcan_get_core_clock(dev, &clock_freq);
+	if (err != 0) {
+		return -EIO;
 	}
 
 	data->dev = dev;
 
+	FLEXCAN_GetDefaultConfig(&flexcan_config);
+	flexcan_config.maxMbNum = FSL_FEATURE_FLEXCAN_HAS_MESSAGE_BUFFER_MAX_NUMBERn(0);
+	flexcan_config.clkSrc = config->clk_source;
+	flexcan_config.baudRate = clock_freq /
+	      (1U + data->timing.prop_seg + data->timing.phase_seg1 +
+	       data->timing.phase_seg2) / data->timing.prescaler;
+	flexcan_config.enableIndividMask = true;
+	flexcan_config.enableLoopBack = false;
+	flexcan_config.disableSelfReception = true;
+	flexcan_config.enableListenOnlyMode = false;
+
+	flexcan_config.timingConfig.rJumpwidth = data->timing.sjw - 1U;
+	flexcan_config.timingConfig.propSeg = data->timing.prop_seg - 1U;
+	flexcan_config.timingConfig.phaseSeg1 = data->timing.phase_seg1 - 1U;
+	flexcan_config.timingConfig.phaseSeg2 = data->timing.phase_seg2 - 1U;
+
+	FLEXCAN_Init(config->base, &flexcan_config, clock_freq);
 	FLEXCAN_TransferCreateHandle(config->base, &data->handle,
 				     mcux_flexcan_transfer_callback, data);