can: bxcan: add support for ST bxCAN controller

Add support for the basic extended CAN controller (bxCAN) found in many
low- to middle-end STM32 SoCs. It supports the Basic Extended CAN
protocol versions 2.0A and B with a maximum bit rate of 1 Mbit/s.

The controller supports two channels (CAN1 as primary and CAN2 as
secondary) and the driver can enable either or both of the channels. They
share some of the required logic (e. g. clocks and filters), and that means
you cannot use the secondary CAN without enabling some hardware resources
managed by the primary CAN.

Each channel has 3 transmit mailboxes, 2 receive FIFOs with 3 stages and
28 scalable filter banks.
It also manages 4 dedicated interrupt vectors:
- transmit interrupt
- FIFO 0 receive interrupt
- FIFO 1 receive interrupt
- status change error interrupt

Driver uses all 3 available mailboxes for transmission and FIFO 0 for
reception. Rx filter rules are configured to the minimum. They accept
all messages and assign filter 0 to CAN1 and filter 14 to CAN2 in
identifier mask mode with 32 bits width. It enables and uses transmit,
receive buffers for FIFO 0 and error and status change interrupts.
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/20230328073328.3949796-6-dario.binacchi@amarulasolutions.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

MAINTAINERS

@@ -4431,6 +4431,13 @@ S:	Maintained
 F:	drivers/scsi/BusLogic.*
 F:	drivers/scsi/FlashPoint.*
 
+BXCAN CAN NETWORK DRIVER
+M:	Dario Binacchi <dario.binacchi@amarulasolutions.com>
+L:	linux-can@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/net/can/st,stm32-bxcan.yaml
+F:	drivers/net/can/bxcan.c
+
 C-MEDIA CMI8788 DRIVER
 M:	Clemens Ladisch <clemens@ladisch.de>
 L:	alsa-devel@alsa-project.org (moderated for non-subscribers)

drivers/net/can/Kconfig

@@ -93,6 +93,18 @@ config CAN_AT91
 	  This is a driver for the SoC CAN controller in Atmel's AT91SAM9263
 	  and AT91SAM9X5 processors.
 
+config CAN_BXCAN
+	tristate "STM32 Basic Extended CAN (bxCAN) devices"
+	depends on OF || ARCH_STM32 || COMPILE_TEST
+	depends on HAS_IOMEM
+	select CAN_RX_OFFLOAD
+	help
+	  Say yes here to build support for the STMicroelectronics STM32 basic
+	  extended CAN Controller (bxCAN).
+
+	  This driver can also be built as a module. If so, the module
+	  will be called bxcan.
+
 config CAN_CAN327
 	tristate "Serial / USB serial ELM327 based OBD-II Interfaces (can327)"
 	depends on TTY

drivers/net/can/Makefile

@@ -14,6 +14,7 @@ obj-y				+= usb/
 obj-y				+= softing/
 
 obj-$(CONFIG_CAN_AT91)		+= at91_can.o
+obj-$(CONFIG_CAN_BXCAN)		+= bxcan.o
 obj-$(CONFIG_CAN_CAN327)	+= can327.o
 obj-$(CONFIG_CAN_CC770)		+= cc770/
 obj-$(CONFIG_CAN_C_CAN)		+= c_can/

drivers/net/can/bxcan.c

+// SPDX-License-Identifier: GPL-2.0
+//
+// bxcan.c - STM32 Basic Extended CAN controller driver
+//
+// Copyright (c) 2022 Dario Binacchi <dario.binacchi@amarulasolutions.com>
+//
+// NOTE: The ST documentation uses the terms master/slave instead of
+// primary/secondary.
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitfield.h>
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+#include <linux/can/rx-offload.h>
+#include <linux/clk.h>
+#include <linux/ethtool.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define BXCAN_NAPI_WEIGHT 3
+#define BXCAN_TIMEOUT_US 10000
+
+#define BXCAN_RX_MB_NUM 2
+#define BXCAN_TX_MB_NUM 3
+
+/* Primary control register (MCR) bits */
+#define BXCAN_MCR_RESET BIT(15)
+#define BXCAN_MCR_TTCM BIT(7)
+#define BXCAN_MCR_ABOM BIT(6)
+#define BXCAN_MCR_AWUM BIT(5)
+#define BXCAN_MCR_NART BIT(4)
+#define BXCAN_MCR_RFLM BIT(3)
+#define BXCAN_MCR_TXFP BIT(2)
+#define BXCAN_MCR_SLEEP BIT(1)
+#define BXCAN_MCR_INRQ BIT(0)
+
+/* Primary status register (MSR) bits */
+#define BXCAN_MSR_ERRI BIT(2)
+#define BXCAN_MSR_SLAK BIT(1)
+#define BXCAN_MSR_INAK BIT(0)
+
+/* Transmit status register (TSR) bits */
+#define BXCAN_TSR_RQCP2 BIT(16)
+#define BXCAN_TSR_RQCP1 BIT(8)
+#define BXCAN_TSR_RQCP0 BIT(0)
+
+/* Receive FIFO 0 register (RF0R) bits */
+#define BXCAN_RF0R_RFOM0 BIT(5)
+#define BXCAN_RF0R_FMP0_MASK GENMASK(1, 0)
+
+/* Interrupt enable register (IER) bits */
+#define BXCAN_IER_SLKIE BIT(17)
+#define BXCAN_IER_WKUIE BIT(16)
+#define BXCAN_IER_ERRIE BIT(15)
+#define BXCAN_IER_LECIE BIT(11)
+#define BXCAN_IER_BOFIE BIT(10)
+#define BXCAN_IER_EPVIE BIT(9)
+#define BXCAN_IER_EWGIE BIT(8)
+#define BXCAN_IER_FOVIE1 BIT(6)
+#define BXCAN_IER_FFIE1 BIT(5)
+#define BXCAN_IER_FMPIE1 BIT(4)
+#define BXCAN_IER_FOVIE0 BIT(3)
+#define BXCAN_IER_FFIE0 BIT(2)
+#define BXCAN_IER_FMPIE0 BIT(1)
+#define BXCAN_IER_TMEIE BIT(0)
+
+/* Error status register (ESR) bits */
+#define BXCAN_ESR_REC_MASK GENMASK(31, 24)
+#define BXCAN_ESR_TEC_MASK GENMASK(23, 16)
+#define BXCAN_ESR_LEC_MASK GENMASK(6, 4)
+#define BXCAN_ESR_BOFF BIT(2)
+#define BXCAN_ESR_EPVF BIT(1)
+#define BXCAN_ESR_EWGF BIT(0)
+
+/* Bit timing register (BTR) bits */
+#define BXCAN_BTR_SILM BIT(31)
+#define BXCAN_BTR_LBKM BIT(30)
+#define BXCAN_BTR_SJW_MASK GENMASK(25, 24)
+#define BXCAN_BTR_TS2_MASK GENMASK(22, 20)
+#define BXCAN_BTR_TS1_MASK GENMASK(19, 16)
+#define BXCAN_BTR_BRP_MASK GENMASK(9, 0)
+
+/* TX mailbox identifier register (TIxR, x = 0..2) bits */
+#define BXCAN_TIxR_STID_MASK GENMASK(31, 21)
+#define BXCAN_TIxR_EXID_MASK GENMASK(31, 3)
+#define BXCAN_TIxR_IDE BIT(2)
+#define BXCAN_TIxR_RTR BIT(1)
+#define BXCAN_TIxR_TXRQ BIT(0)
+
+/* TX mailbox data length and time stamp register (TDTxR, x = 0..2 bits */
+#define BXCAN_TDTxR_DLC_MASK GENMASK(3, 0)
+
+/* RX FIFO mailbox identifier register (RIxR, x = 0..1 */
+#define BXCAN_RIxR_STID_MASK GENMASK(31, 21)
+#define BXCAN_RIxR_EXID_MASK GENMASK(31, 3)
+#define BXCAN_RIxR_IDE BIT(2)
+#define BXCAN_RIxR_RTR BIT(1)
+
+/* RX FIFO mailbox data length and timestamp register (RDTxR, x = 0..1) bits */
+#define BXCAN_RDTxR_TIME_MASK GENMASK(31, 16)
+#define BXCAN_RDTxR_DLC_MASK GENMASK(3, 0)
+
+#define BXCAN_FMR_REG 0x00
+#define BXCAN_FM1R_REG 0x04
+#define BXCAN_FS1R_REG 0x0c
+#define BXCAN_FFA1R_REG 0x14
+#define BXCAN_FA1R_REG 0x1c
+#define BXCAN_FiR1_REG(b) (0x40 + (b) * 8)
+#define BXCAN_FiR2_REG(b) (0x44 + (b) * 8)
+
+#define BXCAN_FILTER_ID(primary) (primary ? 0 : 14)
+
+/* Filter primary register (FMR) bits */
+#define BXCAN_FMR_CANSB_MASK GENMASK(13, 8)
+#define BXCAN_FMR_FINIT BIT(0)
+
+enum bxcan_lec_code {
+	BXCAN_LEC_NO_ERROR = 0,
+	BXCAN_LEC_STUFF_ERROR,
+	BXCAN_LEC_FORM_ERROR,
+	BXCAN_LEC_ACK_ERROR,
+	BXCAN_LEC_BIT1_ERROR,
+	BXCAN_LEC_BIT0_ERROR,
+	BXCAN_LEC_CRC_ERROR,
+	BXCAN_LEC_UNUSED
+};
+
+/* Structure of the message buffer */
+struct bxcan_mb {
+	u32 id;			/* can identifier */
+	u32 dlc;		/* data length control and timestamp */
+	u32 data[2];		/* data */
+};
+
+/* Structure of the hardware registers */
+struct bxcan_regs {
+	u32 mcr;			/* 0x00 - primary control */
+	u32 msr;			/* 0x04 - primary status */
+	u32 tsr;			/* 0x08 - transmit status */
+	u32 rf0r;			/* 0x0c - FIFO 0 */
+	u32 rf1r;			/* 0x10 - FIFO 1 */
+	u32 ier;			/* 0x14 - interrupt enable */
+	u32 esr;			/* 0x18 - error status */
+	u32 btr;			/* 0x1c - bit timing*/
+	u32 reserved0[88];		/* 0x20 */
+	struct bxcan_mb tx_mb[BXCAN_TX_MB_NUM];	/* 0x180 - tx mailbox */
+	struct bxcan_mb rx_mb[BXCAN_RX_MB_NUM];	/* 0x1b0 - rx mailbox */
+};
+
+struct bxcan_priv {
+	struct can_priv can;
+	struct can_rx_offload offload;
+	struct device *dev;
+	struct net_device *ndev;
+
+	struct bxcan_regs __iomem *regs;
+	struct regmap *gcan;
+	int tx_irq;
+	int sce_irq;
+	bool primary;
+	struct clk *clk;
+	spinlock_t rmw_lock;	/* lock for read-modify-write operations */
+	unsigned int tx_head;
+	unsigned int tx_tail;
+	u32 timestamp;
+};
+
+static const struct can_bittiming_const bxcan_bittiming_const = {
+	.name = KBUILD_MODNAME,
+	.tseg1_min = 1,
+	.tseg1_max = 16,
+	.tseg2_min = 1,
+	.tseg2_max = 8,
+	.sjw_max = 4,
+	.brp_min = 1,
+	.brp_max = 1024,
+	.brp_inc = 1,
+};
+
+static inline void bxcan_rmw(struct bxcan_priv *priv, void __iomem *addr,
+			     u32 clear, u32 set)
+{
+	unsigned long flags;
+	u32 old, val;
+
+	spin_lock_irqsave(&priv->rmw_lock, flags);
+	old = readl(addr);
+	val = (old & ~clear) | set;
+	if (val != old)
+		writel(val, addr);
+
+	spin_unlock_irqrestore(&priv->rmw_lock, flags);
+}
+
+static void bxcan_disable_filters(struct bxcan_priv *priv, bool primary)
+{
+	unsigned int fid = BXCAN_FILTER_ID(primary);
+	u32 fmask = BIT(fid);
+
+	regmap_update_bits(priv->gcan, BXCAN_FA1R_REG, fmask, 0);
+}
+
+static void bxcan_enable_filters(struct bxcan_priv *priv, bool primary)
+{
+	unsigned int fid = BXCAN_FILTER_ID(primary);
+	u32 fmask = BIT(fid);
+
+	/* Filter settings:
+	 *
+	 * Accept all messages.
+	 * Assign filter 0 to CAN1 and filter 14 to CAN2 in identifier
+	 * mask mode with 32 bits width.
+	 */
+
+	/* Enter filter initialization mode and assing filters to CAN
+	 * controllers.
+	 */
+	regmap_update_bits(priv->gcan, BXCAN_FMR_REG,
+			   BXCAN_FMR_CANSB_MASK | BXCAN_FMR_FINIT,
+			   FIELD_PREP(BXCAN_FMR_CANSB_MASK, 14) |
+			   BXCAN_FMR_FINIT);
+
+	/* Deactivate filter */
+	regmap_update_bits(priv->gcan, BXCAN_FA1R_REG, fmask, 0);
+
+	/* Two 32-bit registers in identifier mask mode */
+	regmap_update_bits(priv->gcan, BXCAN_FM1R_REG, fmask, 0);
+
+	/* Single 32-bit scale configuration */
+	regmap_update_bits(priv->gcan, BXCAN_FS1R_REG, fmask, fmask);
+
+	/* Assign filter to FIFO 0 */
+	regmap_update_bits(priv->gcan, BXCAN_FFA1R_REG, fmask, 0);
+
+	/* Accept all messages */
+	regmap_write(priv->gcan, BXCAN_FiR1_REG(fid), 0);
+	regmap_write(priv->gcan, BXCAN_FiR2_REG(fid), 0);
+
+	/* Activate filter */
+	regmap_update_bits(priv->gcan, BXCAN_FA1R_REG, fmask, fmask);
+
+	/* Exit filter initialization mode */
+	regmap_update_bits(priv->gcan, BXCAN_FMR_REG, BXCAN_FMR_FINIT, 0);
+}
+
+static inline u8 bxcan_get_tx_head(const struct bxcan_priv *priv)
+{
+	return priv->tx_head % BXCAN_TX_MB_NUM;
+}
+
+static inline u8 bxcan_get_tx_tail(const struct bxcan_priv *priv)
+{
+	return priv->tx_tail % BXCAN_TX_MB_NUM;
+}
+
+static inline u8 bxcan_get_tx_free(const struct bxcan_priv *priv)
+{
+	return BXCAN_TX_MB_NUM - (priv->tx_head - priv->tx_tail);
+}
+
+static bool bxcan_tx_busy(const struct bxcan_priv *priv)
+{
+	if (bxcan_get_tx_free(priv) > 0)
+		return false;
+
+	netif_stop_queue(priv->ndev);
+
+	/* Memory barrier before checking tx_free (head and tail) */
+	smp_mb();
+
+	if (bxcan_get_tx_free(priv) == 0) {
+		netdev_dbg(priv->ndev,
+			   "Stopping tx-queue (tx_head=0x%08x, tx_tail=0x%08x, len=%d).\n",
+			   priv->tx_head, priv->tx_tail,
+			   priv->tx_head - priv->tx_tail);
+
+		return true;
+	}
+
+	netif_start_queue(priv->ndev);
+
+	return false;
+}
+
+static int bxcan_chip_softreset(struct bxcan_priv *priv)
+{
+	struct bxcan_regs __iomem *regs = priv->regs;
+	u32 value;
+
+	bxcan_rmw(priv, &regs->mcr, 0, BXCAN_MCR_RESET);
+	return readx_poll_timeout(readl, &regs->msr, value,
+				  value & BXCAN_MSR_SLAK, BXCAN_TIMEOUT_US,
+				  USEC_PER_SEC);
+}
+
+static int bxcan_enter_init_mode(struct bxcan_priv *priv)
+{
+	struct bxcan_regs __iomem *regs = priv->regs;
+	u32 value;
+
+	bxcan_rmw(priv, &regs->mcr, 0, BXCAN_MCR_INRQ);
+	return readx_poll_timeout(readl, &regs->msr, value,
+				  value & BXCAN_MSR_INAK, BXCAN_TIMEOUT_US,
+				  USEC_PER_SEC);
+}
+
+static int bxcan_leave_init_mode(struct bxcan_priv *priv)
+{
+	struct bxcan_regs __iomem *regs = priv->regs;
+	u32 value;
+
+	bxcan_rmw(priv, &regs->mcr, BXCAN_MCR_INRQ, 0);
+	return readx_poll_timeout(readl, &regs->msr, value,
+				  !(value & BXCAN_MSR_INAK), BXCAN_TIMEOUT_US,
+				  USEC_PER_SEC);
+}
+
+static int bxcan_enter_sleep_mode(struct bxcan_priv *priv)
+{
+	struct bxcan_regs __iomem *regs = priv->regs;
+	u32 value;
+
+	bxcan_rmw(priv, &regs->mcr, 0, BXCAN_MCR_SLEEP);
+	return readx_poll_timeout(readl, &regs->msr, value,
+				  value & BXCAN_MSR_SLAK, BXCAN_TIMEOUT_US,
+				  USEC_PER_SEC);
+}
+
+static int bxcan_leave_sleep_mode(struct bxcan_priv *priv)
+{
+	struct bxcan_regs __iomem *regs = priv->regs;
+	u32 value;
+
+	bxcan_rmw(priv, &regs->mcr, BXCAN_MCR_SLEEP, 0);
+	return readx_poll_timeout(readl, &regs->msr, value,
+				  !(value & BXCAN_MSR_SLAK), BXCAN_TIMEOUT_US,
+				  USEC_PER_SEC);
+}
+
+static inline
+struct bxcan_priv *rx_offload_to_priv(struct can_rx_offload *offload)
+{
+	return container_of(offload, struct bxcan_priv, offload);
+}
+
+static struct sk_buff *bxcan_mailbox_read(struct can_rx_offload *offload,
+					  unsigned int mbxno, u32 *timestamp,
+					  bool drop)
+{
+	struct bxcan_priv *priv = rx_offload_to_priv(offload);
+	struct bxcan_regs __iomem *regs = priv->regs;
+	struct bxcan_mb __iomem *mb_regs = &regs->rx_mb[0];
+	struct sk_buff *skb = NULL;
+	struct can_frame *cf;
+	u32 rf0r, id, dlc;
+
+	rf0r = readl(&regs->rf0r);
+	if (unlikely(drop)) {
+		skb = ERR_PTR(-ENOBUFS);
+		goto mark_as_read;
+	}
+
+	if (!(rf0r & BXCAN_RF0R_FMP0_MASK))
+		goto mark_as_read;
+
+	skb = alloc_can_skb(offload->dev, &cf);
+	if (unlikely(!skb)) {
+		skb = ERR_PTR(-ENOMEM);
+		goto mark_as_read;
+	}
+
+	id = readl(&mb_regs->id);
+	if (id & BXCAN_RIxR_IDE)
+		cf->can_id = FIELD_GET(BXCAN_RIxR_EXID_MASK, id) | CAN_EFF_FLAG;
+	else
+		cf->can_id = FIELD_GET(BXCAN_RIxR_STID_MASK, id) & CAN_SFF_MASK;
+
+	dlc = readl(&mb_regs->dlc);
+	priv->timestamp = FIELD_GET(BXCAN_RDTxR_TIME_MASK, dlc);
+	cf->len = can_cc_dlc2len(FIELD_GET(BXCAN_RDTxR_DLC_MASK, dlc));
+
+	if (id & BXCAN_RIxR_RTR) {
+		cf->can_id |= CAN_RTR_FLAG;
+	} else {
+		int i, j;
+
+		for (i = 0, j = 0; i < cf->len; i += 4, j++)
+			*(u32 *)(cf->data + i) = readl(&mb_regs->data[j]);
+	}
+
+ mark_as_read:
+	rf0r |= BXCAN_RF0R_RFOM0;
+	writel(rf0r, &regs->rf0r);
+	return skb;
+}
+
+static irqreturn_t bxcan_rx_isr(int irq, void *dev_id)
+{
+	struct net_device *ndev = dev_id;
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	struct bxcan_regs __iomem *regs = priv->regs;
+	u32 rf0r;
+
+	rf0r = readl(&regs->rf0r);
+	if (!(rf0r & BXCAN_RF0R_FMP0_MASK))
+		return IRQ_NONE;
+
+	can_rx_offload_irq_offload_fifo(&priv->offload);
+	can_rx_offload_irq_finish(&priv->offload);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t bxcan_tx_isr(int irq, void *dev_id)
+{
+	struct net_device *ndev = dev_id;
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	struct bxcan_regs __iomem *regs = priv->regs;
+	struct net_device_stats *stats = &ndev->stats;
+	u32 tsr, rqcp_bit;
+	int idx;
+
+	tsr = readl(&regs->tsr);
+	if (!(tsr & (BXCAN_TSR_RQCP0 | BXCAN_TSR_RQCP1 | BXCAN_TSR_RQCP2)))
+		return IRQ_NONE;
+
+	while (priv->tx_head - priv->tx_tail > 0) {
+		idx = bxcan_get_tx_tail(priv);
+		rqcp_bit = BXCAN_TSR_RQCP0 << (idx << 3);
+		if (!(tsr & rqcp_bit))
+			break;
+
+		stats->tx_packets++;
+		stats->tx_bytes += can_get_echo_skb(ndev, idx, NULL);
+		priv->tx_tail++;
+	}
+
+	writel(tsr, &regs->tsr);
+
+	if (bxcan_get_tx_free(priv)) {
+		/* Make sure that anybody stopping the queue after
+		 * this sees the new tx_ring->tail.
+		 */
+		smp_mb();
+		netif_wake_queue(ndev);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void bxcan_handle_state_change(struct net_device *ndev, u32 esr)
+{
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	enum can_state new_state = priv->can.state;
+	struct can_berr_counter bec;
+	enum can_state rx_state, tx_state;
+	struct sk_buff *skb;
+	struct can_frame *cf;
+
+	/* Early exit if no error flag is set */
+	if (!(esr & (BXCAN_ESR_EWGF | BXCAN_ESR_EPVF | BXCAN_ESR_BOFF)))
+		return;
+
+	bec.txerr = FIELD_GET(BXCAN_ESR_TEC_MASK, esr);
+	bec.rxerr = FIELD_GET(BXCAN_ESR_REC_MASK, esr);
+
+	if (esr & BXCAN_ESR_BOFF)
+		new_state = CAN_STATE_BUS_OFF;
+	else if (esr & BXCAN_ESR_EPVF)
+		new_state = CAN_STATE_ERROR_PASSIVE;
+	else if (esr & BXCAN_ESR_EWGF)
+		new_state = CAN_STATE_ERROR_WARNING;
+
+	/* state hasn't changed */
+	if (unlikely(new_state == priv->can.state))
+		return;
+
+	skb = alloc_can_err_skb(ndev, &cf);
+
+	tx_state = bec.txerr >= bec.rxerr ? new_state : 0;
+	rx_state = bec.txerr <= bec.rxerr ? new_state : 0;
+	can_change_state(ndev, cf, tx_state, rx_state);
+
+	if (new_state == CAN_STATE_BUS_OFF) {
+		can_bus_off(ndev);
+	} else if (skb) {
+		cf->can_id |= CAN_ERR_CNT;
+		cf->data[6] = bec.txerr;
+		cf->data[7] = bec.rxerr;
+	}
+
+	if (skb) {
+		int err;
+
+		err = can_rx_offload_queue_timestamp(&priv->offload, skb,
+						     priv->timestamp);
+		if (err)
+			ndev->stats.rx_fifo_errors++;
+	}
+}
+
+static void bxcan_handle_bus_err(struct net_device *ndev, u32 esr)
+{
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	enum bxcan_lec_code lec_code;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	lec_code = FIELD_GET(BXCAN_ESR_LEC_MASK, esr);
+
+	/* Early exit if no lec update or no error.
+	 * No lec update means that no CAN bus event has been detected
+	 * since CPU wrote BXCAN_LEC_UNUSED value to status reg.
+	 */
+	if (lec_code == BXCAN_LEC_UNUSED || lec_code == BXCAN_LEC_NO_ERROR)
+		return;
+
+	/* Common for all type of bus errors */
+	priv->can.can_stats.bus_error++;
+
+	/* Propagate the error condition to the CAN stack */
+	skb = alloc_can_err_skb(ndev, &cf);
+	if (skb)
+		cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
+
+	switch (lec_code) {
+	case BXCAN_LEC_STUFF_ERROR:
+		netdev_dbg(ndev, "Stuff error\n");
+		ndev->stats.rx_errors++;
+		if (skb)
+			cf->data[2] |= CAN_ERR_PROT_STUFF;
+		break;
+
+	case BXCAN_LEC_FORM_ERROR:
+		netdev_dbg(ndev, "Form error\n");
+		ndev->stats.rx_errors++;
+		if (skb)
+			cf->data[2] |= CAN_ERR_PROT_FORM;
+		break;
+
+	case BXCAN_LEC_ACK_ERROR:
+		netdev_dbg(ndev, "Ack error\n");
+		ndev->stats.tx_errors++;
+		if (skb) {
+			cf->can_id |= CAN_ERR_ACK;
+			cf->data[3] = CAN_ERR_PROT_LOC_ACK;
+		}
+		break;
+
+	case BXCAN_LEC_BIT1_ERROR:
+		netdev_dbg(ndev, "Bit error (recessive)\n");
+		ndev->stats.tx_errors++;
+		if (skb)
+			cf->data[2] |= CAN_ERR_PROT_BIT1;
+		break;
+
+	case BXCAN_LEC_BIT0_ERROR:
+		netdev_dbg(ndev, "Bit error (dominant)\n");
+		ndev->stats.tx_errors++;
+		if (skb)
+			cf->data[2] |= CAN_ERR_PROT_BIT0;
+		break;
+
+	case BXCAN_LEC_CRC_ERROR:
+		netdev_dbg(ndev, "CRC error\n");
+		ndev->stats.rx_errors++;
+		if (skb) {
+			cf->data[2] |= CAN_ERR_PROT_BIT;
+			cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ;
+		}
+		break;
+
+	default:
+		break;
+	}
+
+	if (skb) {
+		int err;
+
+		err = can_rx_offload_queue_timestamp(&priv->offload, skb,
+						     priv->timestamp);
+		if (err)
+			ndev->stats.rx_fifo_errors++;
+	}
+}
+
+static irqreturn_t bxcan_state_change_isr(int irq, void *dev_id)
+{
+	struct net_device *ndev = dev_id;
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	struct bxcan_regs __iomem *regs = priv->regs;
+	u32 msr, esr;
+
+	msr = readl(&regs->msr);
+	if (!(msr & BXCAN_MSR_ERRI))
+		return IRQ_NONE;
+
+	esr = readl(&regs->esr);
+	bxcan_handle_state_change(ndev, esr);
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
+		bxcan_handle_bus_err(ndev, esr);
+
+	msr |= BXCAN_MSR_ERRI;
+	writel(msr, &regs->msr);
+	can_rx_offload_irq_finish(&priv->offload);
+
+	return IRQ_HANDLED;
+}
+
+static int bxcan_chip_start(struct net_device *ndev)
+{
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	struct bxcan_regs __iomem *regs = priv->regs;
+	struct can_bittiming *bt = &priv->can.bittiming;
+	u32 clr, set;
+	int err;
+
+	err = bxcan_chip_softreset(priv);
+	if (err) {
+		netdev_err(ndev, "failed to reset chip, error %pe\n",
+			   ERR_PTR(err));
+		return err;
+	}
+
+	err = bxcan_leave_sleep_mode(priv);
+	if (err) {
+		netdev_err(ndev, "failed to leave sleep mode, error %pe\n",
+			   ERR_PTR(err));
+		goto failed_leave_sleep;
+	}
+
+	err = bxcan_enter_init_mode(priv);
+	if (err) {
+		netdev_err(ndev, "failed to enter init mode, error %pe\n",
+			   ERR_PTR(err));
+		goto failed_enter_init;
+	}
+
+	/* MCR
+	 *
+	 * select request order priority
+	 * enable time triggered mode
+	 * bus-off state left on sw request
+	 * sleep mode left on sw request
+	 * retransmit automatically on error
+	 * do not lock RX FIFO on overrun
+	 */
+	bxcan_rmw(priv, &regs->mcr,
+		  BXCAN_MCR_ABOM | BXCAN_MCR_AWUM | BXCAN_MCR_NART |
+		  BXCAN_MCR_RFLM, BXCAN_MCR_TTCM | BXCAN_MCR_TXFP);
+
+	/* Bit timing register settings */
+	set = FIELD_PREP(BXCAN_BTR_BRP_MASK, bt->brp - 1) |
+		FIELD_PREP(BXCAN_BTR_TS1_MASK, bt->phase_seg1 +
+			   bt->prop_seg - 1) |
+		FIELD_PREP(BXCAN_BTR_TS2_MASK, bt->phase_seg2 - 1) |
+		FIELD_PREP(BXCAN_BTR_SJW_MASK, bt->sjw - 1);
+
+	/* loopback + silent mode put the controller in test mode,
+	 * useful for hot self-test
+	 */
+	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
+		set |= BXCAN_BTR_LBKM;
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		set |= BXCAN_BTR_SILM;
+
+	bxcan_rmw(priv, &regs->btr, BXCAN_BTR_SILM | BXCAN_BTR_LBKM |
+		  BXCAN_BTR_BRP_MASK | BXCAN_BTR_TS1_MASK | BXCAN_BTR_TS2_MASK |
+		  BXCAN_BTR_SJW_MASK, set);
+
+	bxcan_enable_filters(priv, priv->primary);
+
+	/* Clear all internal status */
+	priv->tx_head = 0;
+	priv->tx_tail = 0;
+
+	err = bxcan_leave_init_mode(priv);
+	if (err) {
+		netdev_err(ndev, "failed to leave init mode, error %pe\n",
+			   ERR_PTR(err));
+		goto failed_leave_init;
+	}
+
+	/* Set a `lec` value so that we can check for updates later */
+	bxcan_rmw(priv, &regs->esr, BXCAN_ESR_LEC_MASK,
+		  FIELD_PREP(BXCAN_ESR_LEC_MASK, BXCAN_LEC_UNUSED));
+
+	/* IER
+	 *
+	 * Enable interrupt for:
+	 * bus-off
+	 * passive error
+	 * warning error
+	 * last error code
+	 * RX FIFO pending message
+	 * TX mailbox empty
+	 */
+	clr = BXCAN_IER_WKUIE | BXCAN_IER_SLKIE |  BXCAN_IER_FOVIE1 |
+		BXCAN_IER_FFIE1 | BXCAN_IER_FMPIE1 | BXCAN_IER_FOVIE0 |
+		BXCAN_IER_FFIE0;
+	set = BXCAN_IER_ERRIE | BXCAN_IER_BOFIE | BXCAN_IER_EPVIE |
+		BXCAN_IER_EWGIE | BXCAN_IER_FMPIE0 | BXCAN_IER_TMEIE;
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
+		set |= BXCAN_IER_LECIE;
+	else
+		clr |= BXCAN_IER_LECIE;
+
+	bxcan_rmw(priv, &regs->ier, clr, set);
+
+	priv->can.state = CAN_STATE_ERROR_ACTIVE;
+	return 0;
+
+failed_leave_init:
+failed_enter_init:
+failed_leave_sleep:
+	bxcan_chip_softreset(priv);
+	return err;
+}
+
+static int bxcan_open(struct net_device *ndev)
+{
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	int err;
+
+	err = clk_prepare_enable(priv->clk);
+	if (err) {
+		netdev_err(ndev, "failed to enable clock, error %pe\n",
+			   ERR_PTR(err));
+		return err;
+	}
+
+	err = open_candev(ndev);
+	if (err) {
+		netdev_err(ndev, "open_candev() failed, error %pe\n",
+			   ERR_PTR(err));
+		goto out_disable_clock;
+	}
+
+	can_rx_offload_enable(&priv->offload);
+	err = request_irq(ndev->irq, bxcan_rx_isr, IRQF_SHARED, ndev->name,
+			  ndev);
+	if (err) {
+		netdev_err(ndev, "failed to register rx irq(%d), error %pe\n",
+			   ndev->irq, ERR_PTR(err));
+		goto out_close_candev;
+	}
+
+	err = request_irq(priv->tx_irq, bxcan_tx_isr, IRQF_SHARED, ndev->name,
+			  ndev);
+	if (err) {
+		netdev_err(ndev, "failed to register tx irq(%d), error %pe\n",
+			   priv->tx_irq, ERR_PTR(err));
+		goto out_free_rx_irq;
+	}
+
+	err = request_irq(priv->sce_irq, bxcan_state_change_isr, IRQF_SHARED,
+			  ndev->name, ndev);
+	if (err) {
+		netdev_err(ndev, "failed to register sce irq(%d), error %pe\n",
+			   priv->sce_irq, ERR_PTR(err));
+		goto out_free_tx_irq;
+	}
+
+	err = bxcan_chip_start(ndev);
+	if (err)
+		goto out_free_sce_irq;
+
+	netif_start_queue(ndev);
+	return 0;
+
+out_free_sce_irq:
+	free_irq(priv->sce_irq, ndev);
+out_free_tx_irq:
+	free_irq(priv->tx_irq, ndev);
+out_free_rx_irq:
+	free_irq(ndev->irq, ndev);
+out_close_candev:
+	can_rx_offload_disable(&priv->offload);
+	close_candev(ndev);
+out_disable_clock:
+	clk_disable_unprepare(priv->clk);
+	return err;
+}
+
+static void bxcan_chip_stop(struct net_device *ndev)
+{
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	struct bxcan_regs __iomem *regs = priv->regs;
+
+	/* disable all interrupts */
+	bxcan_rmw(priv, &regs->ier, BXCAN_IER_SLKIE | BXCAN_IER_WKUIE |
+		  BXCAN_IER_ERRIE | BXCAN_IER_LECIE | BXCAN_IER_BOFIE |
+		  BXCAN_IER_EPVIE | BXCAN_IER_EWGIE | BXCAN_IER_FOVIE1 |
+		  BXCAN_IER_FFIE1 | BXCAN_IER_FMPIE1 | BXCAN_IER_FOVIE0 |
+		  BXCAN_IER_FFIE0 | BXCAN_IER_FMPIE0 | BXCAN_IER_TMEIE, 0);
+	bxcan_disable_filters(priv, priv->primary);
+	bxcan_enter_sleep_mode(priv);
+	priv->can.state = CAN_STATE_STOPPED;
+}
+
+static int bxcan_stop(struct net_device *ndev)
+{
+	struct bxcan_priv *priv = netdev_priv(ndev);
+
+	netif_stop_queue(ndev);
+	bxcan_chip_stop(ndev);
+	free_irq(ndev->irq, ndev);
+	free_irq(priv->tx_irq, ndev);
+	free_irq(priv->sce_irq, ndev);
+	can_rx_offload_disable(&priv->offload);
+	close_candev(ndev);
+	clk_disable_unprepare(priv->clk);
+	return 0;
+}
+
+static netdev_tx_t bxcan_start_xmit(struct sk_buff *skb,
+				    struct net_device *ndev)
+{
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	struct can_frame *cf = (struct can_frame *)skb->data;
+	struct bxcan_regs __iomem *regs = priv->regs;
+	struct bxcan_mb __iomem *mb_regs;
+	unsigned int idx;
+	u32 id;
+	int i, j;
+
+	if (can_dropped_invalid_skb(ndev, skb))
+		return NETDEV_TX_OK;
+
+	if (bxcan_tx_busy(priv))
+		return NETDEV_TX_BUSY;
+
+	idx = bxcan_get_tx_head(priv);
+	priv->tx_head++;
+	if (bxcan_get_tx_free(priv) == 0)
+		netif_stop_queue(ndev);
+
+	mb_regs = &regs->tx_mb[idx];
+	if (cf->can_id & CAN_EFF_FLAG)
+		id = FIELD_PREP(BXCAN_TIxR_EXID_MASK, cf->can_id) |
+			BXCAN_TIxR_IDE;
+	else
+		id = FIELD_PREP(BXCAN_TIxR_STID_MASK, cf->can_id);
+
+	if (cf->can_id & CAN_RTR_FLAG) { /* Remote transmission request */
+		id |= BXCAN_TIxR_RTR;
+	} else {
+		for (i = 0, j = 0; i < cf->len; i += 4, j++)
+			writel(*(u32 *)(cf->data + i), &mb_regs->data[j]);
+	}
+
+	writel(FIELD_PREP(BXCAN_TDTxR_DLC_MASK, cf->len), &mb_regs->dlc);
+
+	can_put_echo_skb(skb, ndev, idx, 0);
+
+	/* Start transmission */
+	writel(id | BXCAN_TIxR_TXRQ, &mb_regs->id);
+
+	return NETDEV_TX_OK;
+}
+
+static const struct net_device_ops bxcan_netdev_ops = {
+	.ndo_open = bxcan_open,
+	.ndo_stop = bxcan_stop,
+	.ndo_start_xmit = bxcan_start_xmit,
+	.ndo_change_mtu = can_change_mtu,
+};
+
+static const struct ethtool_ops bxcan_ethtool_ops = {
+	.get_ts_info = ethtool_op_get_ts_info,
+};
+
+static int bxcan_do_set_mode(struct net_device *ndev, enum can_mode mode)
+{
+	int err;
+
+	switch (mode) {
+	case CAN_MODE_START:
+		err = bxcan_chip_start(ndev);
+		if (err)
+			return err;
+
+		netif_wake_queue(ndev);
+		break;
+
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int bxcan_get_berr_counter(const struct net_device *ndev,
+				  struct can_berr_counter *bec)
+{
+	struct bxcan_priv *priv = netdev_priv(ndev);
+	struct bxcan_regs __iomem *regs = priv->regs;
+	u32 esr;
+	int err;
+
+	err = clk_prepare_enable(priv->clk);
+	if (err)
+		return err;
+
+	esr = readl(&regs->esr);
+	bec->txerr = FIELD_GET(BXCAN_ESR_TEC_MASK, esr);
+	bec->rxerr = FIELD_GET(BXCAN_ESR_REC_MASK, esr);
+	clk_disable_unprepare(priv->clk);
+	return 0;
+}
+
+static int bxcan_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	struct net_device *ndev;
+	struct bxcan_priv *priv;
+	struct clk *clk = NULL;
+	void __iomem *regs;
+	struct regmap *gcan;
+	bool primary;
+	int err, rx_irq, tx_irq, sce_irq;
+
+	regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(regs)) {
+		dev_err(dev, "failed to get base address\n");
+		return PTR_ERR(regs);
+	}
+
+	gcan = syscon_regmap_lookup_by_phandle(np, "st,gcan");
+	if (IS_ERR(gcan)) {
+		dev_err(dev, "failed to get shared memory base address\n");
+		return PTR_ERR(gcan);
+	}
+
+	primary = of_property_read_bool(np, "st,can-primary");
+	clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(dev, "failed to get clock\n");
+		return PTR_ERR(clk);
+	}
+
+	rx_irq = platform_get_irq_byname(pdev, "rx0");
+	if (rx_irq < 0) {
+		dev_err(dev, "failed to get rx0 irq\n");
+		return rx_irq;
+	}
+
+	tx_irq = platform_get_irq_byname(pdev, "tx");
+	if (tx_irq < 0) {
+		dev_err(dev, "failed to get tx irq\n");
+		return tx_irq;
+	}
+
+	sce_irq = platform_get_irq_byname(pdev, "sce");
+	if (sce_irq < 0) {
+		dev_err(dev, "failed to get sce irq\n");
+		return sce_irq;
+	}
+
+	ndev = alloc_candev(sizeof(struct bxcan_priv), BXCAN_TX_MB_NUM);
+	if (!ndev) {
+		dev_err(dev, "alloc_candev() failed\n");
+		return -ENOMEM;
+	}
+
+	priv = netdev_priv(ndev);
+	platform_set_drvdata(pdev, ndev);
+	SET_NETDEV_DEV(ndev, dev);
+	ndev->netdev_ops = &bxcan_netdev_ops;
+	ndev->ethtool_ops = &bxcan_ethtool_ops;
+	ndev->irq = rx_irq;
+	ndev->flags |= IFF_ECHO;
+
+	priv->dev = dev;
+	priv->ndev = ndev;
+	priv->regs = regs;
+	priv->gcan = gcan;
+	priv->clk = clk;
+	priv->tx_irq = tx_irq;
+	priv->sce_irq = sce_irq;
+	priv->primary = primary;
+	priv->can.clock.freq = clk_get_rate(clk);
+	spin_lock_init(&priv->rmw_lock);
+	priv->tx_head = 0;
+	priv->tx_tail = 0;
+	priv->can.bittiming_const = &bxcan_bittiming_const;
+	priv->can.do_set_mode = bxcan_do_set_mode;
+	priv->can.do_get_berr_counter = bxcan_get_berr_counter;
+	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
+		CAN_CTRLMODE_LISTENONLY	| CAN_CTRLMODE_BERR_REPORTING;
+
+	priv->offload.mailbox_read = bxcan_mailbox_read;
+	err = can_rx_offload_add_fifo(ndev, &priv->offload, BXCAN_NAPI_WEIGHT);
+	if (err) {
+		dev_err(dev, "failed to add FIFO rx_offload\n");
+		goto out_free_candev;
+	}
+
+	err = register_candev(ndev);
+	if (err) {
+		dev_err(dev, "failed to register netdev\n");
+		goto out_can_rx_offload_del;
+	}
+
+	dev_info(dev, "clk: %d Hz, IRQs: %d, %d, %d\n", priv->can.clock.freq,
+		 tx_irq, rx_irq, sce_irq);
+	return 0;
+
+out_can_rx_offload_del:
+	can_rx_offload_del(&priv->offload);
+out_free_candev:
+	free_candev(ndev);
+	return err;
+}
+
+static int bxcan_remove(struct platform_device *pdev)
+{
+	struct net_device *ndev = platform_get_drvdata(pdev);
+	struct bxcan_priv *priv = netdev_priv(ndev);
+
+	unregister_candev(ndev);
+	clk_disable_unprepare(priv->clk);
+	can_rx_offload_del(&priv->offload);
+	free_candev(ndev);
+	return 0;
+}
+
+static int __maybe_unused bxcan_suspend(struct device *dev)
+{
+	struct net_device *ndev = dev_get_drvdata(dev);
+	struct bxcan_priv *priv = netdev_priv(ndev);
+
+	if (!netif_running(ndev))
+		return 0;
+
+	netif_stop_queue(ndev);
+	netif_device_detach(ndev);
+
+	bxcan_enter_sleep_mode(priv);
+	priv->can.state = CAN_STATE_SLEEPING;
+	clk_disable_unprepare(priv->clk);
+	return 0;
+}
+
+static int __maybe_unused bxcan_resume(struct device *dev)
+{
+	struct net_device *ndev = dev_get_drvdata(dev);
+	struct bxcan_priv *priv = netdev_priv(ndev);
+
+	if (!netif_running(ndev))
+		return 0;
+
+	clk_prepare_enable(priv->clk);
+	bxcan_leave_sleep_mode(priv);
+	priv->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	netif_device_attach(ndev);
+	netif_start_queue(ndev);
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(bxcan_pm_ops, bxcan_suspend, bxcan_resume);
+
+static const struct of_device_id bxcan_of_match[] = {
+	{.compatible = "st,stm32f4-bxcan"},
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, bxcan_of_match);
+
+static struct platform_driver bxcan_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.pm = &bxcan_pm_ops,
+		.of_match_table = bxcan_of_match,
+	},
+	.probe = bxcan_probe,
+	.remove = bxcan_remove,
+};
+
+module_platform_driver(bxcan_driver);
+
+MODULE_AUTHOR("Dario Binacchi <dario.binacchi@amarulasolutions.com>");
+MODULE_DESCRIPTION("STMicroelectronics Basic Extended CAN controller driver");
+MODULE_LICENSE("GPL");