// SPDX-License-Identifier: GPL-2.0
// CAN bus driver for Bosch M_CAN controller
// Copyright (C) 2014 Freescale Semiconductor, Inc.
//      Dong Aisheng <aisheng.dong@nxp.com>
// Copyright (C) 2018-19 Texas Instruments Incorporated - http://www.ti.com/

/* Bosch M_CAN user manual can be obtained from:
 * https://github.com/linux-can/can-doc/tree/master/m_can
 */

#include <linux/bitfield.h>
#include <linux/can/dev.h>
#include <linux/ethtool.h>
#include <linux/hrtimer.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/of.h>
#include <linux/phy/phy.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>

#include "m_can.h"

/* registers definition */
enum m_can_reg {
        M_CAN_CREL      = 0x0,
        M_CAN_ENDN      = 0x4,
        M_CAN_CUST      = 0x8,
        M_CAN_DBTP      = 0xc,
        M_CAN_TEST      = 0x10,
        M_CAN_RWD       = 0x14,
        M_CAN_CCCR      = 0x18,
        M_CAN_NBTP      = 0x1c,
        M_CAN_TSCC      = 0x20,
        M_CAN_TSCV      = 0x24,
        M_CAN_TOCC      = 0x28,
        M_CAN_TOCV      = 0x2c,
        M_CAN_ECR       = 0x40,
        M_CAN_PSR       = 0x44,
        /* TDCR Register only available for version >=3.1.x */
        M_CAN_TDCR      = 0x48,
        M_CAN_IR        = 0x50,
        M_CAN_IE        = 0x54,
        M_CAN_ILS       = 0x58,
        M_CAN_ILE       = 0x5c,
        M_CAN_GFC       = 0x80,
        M_CAN_SIDFC     = 0x84,
        M_CAN_XIDFC     = 0x88,
        M_CAN_XIDAM     = 0x90,
        M_CAN_HPMS      = 0x94,
        M_CAN_NDAT1     = 0x98,
        M_CAN_NDAT2     = 0x9c,
        M_CAN_RXF0C     = 0xa0,
        M_CAN_RXF0S     = 0xa4,
        M_CAN_RXF0A     = 0xa8,
        M_CAN_RXBC      = 0xac,
        M_CAN_RXF1C     = 0xb0,
        M_CAN_RXF1S     = 0xb4,
        M_CAN_RXF1A     = 0xb8,
        M_CAN_RXESC     = 0xbc,
        M_CAN_TXBC      = 0xc0,
        M_CAN_TXFQS     = 0xc4,
        M_CAN_TXESC     = 0xc8,
        M_CAN_TXBRP     = 0xcc,
        M_CAN_TXBAR     = 0xd0,
        M_CAN_TXBCR     = 0xd4,
        M_CAN_TXBTO     = 0xd8,
        M_CAN_TXBCF     = 0xdc,
        M_CAN_TXBTIE    = 0xe0,
        M_CAN_TXBCIE    = 0xe4,
        M_CAN_TXEFC     = 0xf0,
        M_CAN_TXEFS     = 0xf4,
        M_CAN_TXEFA     = 0xf8,
};

/* message ram configuration data length */
#define MRAM_CFG_LEN    8

/* Core Release Register (CREL) */
#define CREL_REL_MASK           GENMASK(31, 28)
#define CREL_STEP_MASK          GENMASK(27, 24)
#define CREL_SUBSTEP_MASK       GENMASK(23, 20)

/* Data Bit Timing & Prescaler Register (DBTP) */
#define DBTP_TDC                BIT(23)
#define DBTP_DBRP_MASK          GENMASK(20, 16)
#define DBTP_DTSEG1_MASK        GENMASK(12, 8)
#define DBTP_DTSEG2_MASK        GENMASK(7, 4)
#define DBTP_DSJW_MASK          GENMASK(3, 0)

/* Transmitter Delay Compensation Register (TDCR) */
#define TDCR_TDCO_MASK          GENMASK(14, 8)
#define TDCR_TDCF_MASK          GENMASK(6, 0)

/* Test Register (TEST) */
#define TEST_LBCK               BIT(4)

/* CC Control Register (CCCR) */
#define CCCR_TXP                BIT(14)
#define CCCR_TEST               BIT(7)
#define CCCR_DAR                BIT(6)
#define CCCR_MON                BIT(5)
#define CCCR_CSR                BIT(4)
#define CCCR_CSA                BIT(3)
#define CCCR_ASM                BIT(2)
#define CCCR_CCE                BIT(1)
#define CCCR_INIT               BIT(0)
/* for version 3.0.x */
#define CCCR_CMR_MASK           GENMASK(11, 10)
#define CCCR_CMR_CANFD          0x1
#define CCCR_CMR_CANFD_BRS      0x2
#define CCCR_CMR_CAN            0x3
#define CCCR_CME_MASK           GENMASK(9, 8)
#define CCCR_CME_CAN            0
#define CCCR_CME_CANFD          0x1
#define CCCR_CME_CANFD_BRS      0x2
/* for version >=3.1.x */
#define CCCR_EFBI               BIT(13)
#define CCCR_PXHD               BIT(12)
#define CCCR_BRSE               BIT(9)
#define CCCR_FDOE               BIT(8)
/* for version >=3.2.x */
#define CCCR_NISO               BIT(15)
/* for version >=3.3.x */
#define CCCR_WMM                BIT(11)
#define CCCR_UTSU               BIT(10)

/* Nominal Bit Timing & Prescaler Register (NBTP) */
#define NBTP_NSJW_MASK          GENMASK(31, 25)
#define NBTP_NBRP_MASK          GENMASK(24, 16)
#define NBTP_NTSEG1_MASK        GENMASK(15, 8)
#define NBTP_NTSEG2_MASK        GENMASK(6, 0)

/* Timestamp Counter Configuration Register (TSCC) */
#define TSCC_TCP_MASK           GENMASK(19, 16)
#define TSCC_TSS_MASK           GENMASK(1, 0)
#define TSCC_TSS_DISABLE        0x0
#define TSCC_TSS_INTERNAL       0x1
#define TSCC_TSS_EXTERNAL       0x2

/* Timestamp Counter Value Register (TSCV) */
#define TSCV_TSC_MASK           GENMASK(15, 0)

/* Error Counter Register (ECR) */
#define ECR_RP                  BIT(15)
#define ECR_REC_MASK            GENMASK(14, 8)
#define ECR_TEC_MASK            GENMASK(7, 0)

/* Protocol Status Register (PSR) */
#define PSR_BO          BIT(7)
#define PSR_EW          BIT(6)
#define PSR_EP          BIT(5)
#define PSR_LEC_MASK    GENMASK(2, 0)
#define PSR_DLEC_MASK   GENMASK(10, 8)

/* Interrupt Register (IR) */
#define IR_ALL_INT      0xffffffff

/* Renamed bits for versions > 3.1.x */
#define IR_ARA          BIT(29)
#define IR_PED          BIT(28)
#define IR_PEA          BIT(27)

/* Bits for version 3.0.x */
#define IR_STE          BIT(31)
#define IR_FOE          BIT(30)
#define IR_ACKE         BIT(29)
#define IR_BE           BIT(28)
#define IR_CRCE         BIT(27)
#define IR_WDI          BIT(26)
#define IR_BO           BIT(25)
#define IR_EW           BIT(24)
#define IR_EP           BIT(23)
#define IR_ELO          BIT(22)
#define IR_BEU          BIT(21)
#define IR_BEC          BIT(20)
#define IR_DRX          BIT(19)
#define IR_TOO          BIT(18)
#define IR_MRAF         BIT(17)
#define IR_TSW          BIT(16)
#define IR_TEFL         BIT(15)
#define IR_TEFF         BIT(14)
#define IR_TEFW         BIT(13)
#define IR_TEFN         BIT(12)
#define IR_TFE          BIT(11)
#define IR_TCF          BIT(10)
#define IR_TC           BIT(9)
#define IR_HPM          BIT(8)
#define IR_RF1L         BIT(7)
#define IR_RF1F         BIT(6)
#define IR_RF1W         BIT(5)
#define IR_RF1N         BIT(4)
#define IR_RF0L         BIT(3)
#define IR_RF0F         BIT(2)
#define IR_RF0W         BIT(1)
#define IR_RF0N         BIT(0)
#define IR_ERR_STATE    (IR_BO | IR_EW | IR_EP)

/* Interrupts for version 3.0.x */
#define IR_ERR_LEC_30X  (IR_STE | IR_FOE | IR_ACKE | IR_BE | IR_CRCE)
#define IR_ERR_BUS_30X  (IR_ERR_LEC_30X | IR_WDI | IR_BEU | IR_BEC | \
                         IR_TOO | IR_MRAF | IR_TSW | IR_TEFL | IR_RF1L | \
                         IR_RF0L)
#define IR_ERR_ALL_30X  (IR_ERR_STATE | IR_ERR_BUS_30X)

/* Interrupts for version >= 3.1.x */
#define IR_ERR_LEC_31X  (IR_PED | IR_PEA)
#define IR_ERR_BUS_31X  (IR_ERR_LEC_31X | IR_WDI | IR_BEU | IR_BEC | \
                         IR_TOO | IR_MRAF | IR_TSW | IR_TEFL | IR_RF1L | \
                         IR_RF0L)
#define IR_ERR_ALL_31X  (IR_ERR_STATE | IR_ERR_BUS_31X)

/* Interrupt Line Select (ILS) */
#define ILS_ALL_INT0    0x0
#define ILS_ALL_INT1    0xFFFFFFFF

/* Interrupt Line Enable (ILE) */
#define ILE_EINT1       BIT(1)
#define ILE_EINT0       BIT(0)

/* Rx FIFO 0/1 Configuration (RXF0C/RXF1C) */
#define RXFC_FWM_MASK   GENMASK(30, 24)
#define RXFC_FS_MASK    GENMASK(22, 16)

/* Rx FIFO 0/1 Status (RXF0S/RXF1S) */
#define RXFS_RFL        BIT(25)
#define RXFS_FF         BIT(24)
#define RXFS_FPI_MASK   GENMASK(21, 16)
#define RXFS_FGI_MASK   GENMASK(13, 8)
#define RXFS_FFL_MASK   GENMASK(6, 0)

/* Rx Buffer / FIFO Element Size Configuration (RXESC) */
#define RXESC_RBDS_MASK         GENMASK(10, 8)
#define RXESC_F1DS_MASK         GENMASK(6, 4)
#define RXESC_F0DS_MASK         GENMASK(2, 0)
#define RXESC_64B               0x7

/* Tx Buffer Configuration (TXBC) */
#define TXBC_TFQS_MASK          GENMASK(29, 24)
#define TXBC_NDTB_MASK          GENMASK(21, 16)

/* Tx FIFO/Queue Status (TXFQS) */
#define TXFQS_TFQF              BIT(21)
#define TXFQS_TFQPI_MASK        GENMASK(20, 16)
#define TXFQS_TFGI_MASK         GENMASK(12, 8)
#define TXFQS_TFFL_MASK         GENMASK(5, 0)

/* Tx Buffer Element Size Configuration (TXESC) */
#define TXESC_TBDS_MASK         GENMASK(2, 0)
#define TXESC_TBDS_64B          0x7

/* Tx Event FIFO Configuration (TXEFC) */
#define TXEFC_EFWM_MASK         GENMASK(29, 24)
#define TXEFC_EFS_MASK          GENMASK(21, 16)

/* Tx Event FIFO Status (TXEFS) */
#define TXEFS_TEFL              BIT(25)
#define TXEFS_EFF               BIT(24)
#define TXEFS_EFGI_MASK         GENMASK(12, 8)
#define TXEFS_EFFL_MASK         GENMASK(5, 0)

/* Tx Event FIFO Acknowledge (TXEFA) */
#define TXEFA_EFAI_MASK         GENMASK(4, 0)

/* Message RAM Configuration (in bytes) */
#define SIDF_ELEMENT_SIZE       4
#define XIDF_ELEMENT_SIZE       8
#define RXF0_ELEMENT_SIZE       72
#define RXF1_ELEMENT_SIZE       72
#define RXB_ELEMENT_SIZE        72
#define TXE_ELEMENT_SIZE        8
#define TXB_ELEMENT_SIZE        72

/* Message RAM Elements */
#define M_CAN_FIFO_ID           0x0
#define M_CAN_FIFO_DLC          0x4
#define M_CAN_FIFO_DATA         0x8

/* Rx Buffer Element */
/* R0 */
#define RX_BUF_ESI              BIT(31)
#define RX_BUF_XTD              BIT(30)
#define RX_BUF_RTR              BIT(29)
/* R1 */
#define RX_BUF_ANMF             BIT(31)
#define RX_BUF_FDF              BIT(21)
#define RX_BUF_BRS              BIT(20)
#define RX_BUF_RXTS_MASK        GENMASK(15, 0)

/* Tx Buffer Element */
/* T0 */
#define TX_BUF_ESI              BIT(31)
#define TX_BUF_XTD              BIT(30)
#define TX_BUF_RTR              BIT(29)
/* T1 */
#define TX_BUF_EFC              BIT(23)
#define TX_BUF_FDF              BIT(21)
#define TX_BUF_BRS              BIT(20)
#define TX_BUF_MM_MASK          GENMASK(31, 24)
#define TX_BUF_DLC_MASK         GENMASK(19, 16)

/* Tx event FIFO Element */
/* E1 */
#define TX_EVENT_MM_MASK        GENMASK(31, 24)
#define TX_EVENT_TXTS_MASK      GENMASK(15, 0)

/* Hrtimer polling interval */
#define HRTIMER_POLL_INTERVAL_MS                1

/* The ID and DLC registers are adjacent in M_CAN FIFO memory,
 * and we can save a (potentially slow) bus round trip by combining
 * reads and writes to them.
 */
struct id_and_dlc {
        u32 id;
        u32 dlc;
};

struct m_can_fifo_element {
        u32 id;
        u32 dlc;
        u8 data[CANFD_MAX_DLEN];
};

static inline u32 m_can_read(struct m_can_classdev *cdev, enum m_can_reg reg)
{
        return cdev->ops->read_reg(cdev, reg);
}

static inline void m_can_write(struct m_can_classdev *cdev, enum m_can_reg reg,
                               u32 val)
{
        cdev->ops->write_reg(cdev, reg, val);
}

static int
m_can_fifo_read(struct m_can_classdev *cdev,
                u32 fgi, unsigned int offset, void *val, size_t val_count)
{
        u32 addr_offset = cdev->mcfg[MRAM_RXF0].off + fgi * RXF0_ELEMENT_SIZE +
                offset;

        if (val_count == 0)
                return 0;

        return cdev->ops->read_fifo(cdev, addr_offset, val, val_count);
}

static int
m_can_fifo_write(struct m_can_classdev *cdev,
                 u32 fpi, unsigned int offset, const void *val, size_t val_count)
{
        u32 addr_offset = cdev->mcfg[MRAM_TXB].off + fpi * TXB_ELEMENT_SIZE +
                offset;

        if (val_count == 0)
                return 0;

        return cdev->ops->write_fifo(cdev, addr_offset, val, val_count);
}

static inline int m_can_fifo_write_no_off(struct m_can_classdev *cdev,
                                          u32 fpi, u32 val)
{
        return cdev->ops->write_fifo(cdev, fpi, &val, 1);
}

static int
m_can_txe_fifo_read(struct m_can_classdev *cdev, u32 fgi, u32 offset, u32 *val)
{
        u32 addr_offset = cdev->mcfg[MRAM_TXE].off + fgi * TXE_ELEMENT_SIZE +
                offset;

        return cdev->ops->read_fifo(cdev, addr_offset, val, 1);
}

static int m_can_cccr_update_bits(struct m_can_classdev *cdev, u32 mask, u32 val)
{
        u32 val_before = m_can_read(cdev, M_CAN_CCCR);
        u32 val_after = (val_before & ~mask) | val;
        size_t tries = 10;

        if (!(mask & CCCR_INIT) && !(val_before & CCCR_INIT)) {
                netdev_err(cdev->net,
                           "refusing to configure device when in normal mode\n");
                return -EBUSY;
        }

        /* The chip should be in standby mode when changing the CCCR register,
         * and some chips set the CSR and CSA bits when in standby. Furthermore,
         * the CSR and CSA bits should be written as zeros, even when they read
         * ones.
         */
        val_after &= ~(CCCR_CSR | CCCR_CSA);

        while (tries--) {
                u32 val_read;

                /* Write the desired value in each try, as setting some bits in
                 * the CCCR register require other bits to be set first. E.g.
                 * setting the NISO bit requires setting the CCE bit first.
                 */
                m_can_write(cdev, M_CAN_CCCR, val_after);

                val_read = m_can_read(cdev, M_CAN_CCCR) & ~(CCCR_CSR | CCCR_CSA);

                if (val_read == val_after)
                        return 0;

                usleep_range(1, 5);
        }

        return -ETIMEDOUT;
}

static int m_can_config_enable(struct m_can_classdev *cdev)
{
        int err;

        /* CCCR_INIT must be set in order to set CCCR_CCE, but access to
         * configuration registers should only be enabled when in standby mode,
         * where CCCR_INIT is always set.
         */
        err = m_can_cccr_update_bits(cdev, CCCR_CCE, CCCR_CCE);
        if (err)
                netdev_err(cdev->net, "failed to enable configuration mode\n");

        return err;
}

static int m_can_config_disable(struct m_can_classdev *cdev)
{
        int err;

        /* Only clear CCCR_CCE, since CCCR_INIT cannot be cleared while in
         * standby mode
         */
        err = m_can_cccr_update_bits(cdev, CCCR_CCE, 0);
        if (err)
                netdev_err(cdev->net, "failed to disable configuration registers\n");

        return err;
}

static void m_can_interrupt_enable(struct m_can_classdev *cdev, u32 interrupts)
{
        if (cdev->active_interrupts == interrupts)
                return;
        m_can_write(cdev, M_CAN_IE, interrupts);
        cdev->active_interrupts = interrupts;
}

static void m_can_coalescing_disable(struct m_can_classdev *cdev)
{
        u32 new_interrupts = cdev->active_interrupts | IR_RF0N | IR_TEFN;

        if (!cdev->net->irq)
                return;

        hrtimer_cancel(&cdev->hrtimer);
        m_can_interrupt_enable(cdev, new_interrupts);
}

static inline void m_can_enable_all_interrupts(struct m_can_classdev *cdev)
{
        if (!cdev->net->irq) {
                netdev_dbg(cdev->net, "Start hrtimer\n");
                hrtimer_start(&cdev->hrtimer,
                              ms_to_ktime(HRTIMER_POLL_INTERVAL_MS),
                              HRTIMER_MODE_REL_PINNED);
        }

        /* Only interrupt line 0 is used in this driver */
        m_can_write(cdev, M_CAN_ILE, ILE_EINT0);
}

static inline void m_can_disable_all_interrupts(struct m_can_classdev *cdev)
{
        m_can_coalescing_disable(cdev);
        m_can_write(cdev, M_CAN_ILE, 0x0);

        if (!cdev->net->irq) {
                netdev_dbg(cdev->net, "Stop hrtimer\n");
                hrtimer_try_to_cancel(&cdev->hrtimer);
        }
}

/* Retrieve internal timestamp counter from TSCV.TSC, and shift it to 32-bit
 * width.
 */
static u32 m_can_get_timestamp(struct m_can_classdev *cdev)
{
        u32 tscv;
        u32 tsc;

        tscv = m_can_read(cdev, M_CAN_TSCV);
        tsc = FIELD_GET(TSCV_TSC_MASK, tscv);

        return (tsc << 16);
}

static void m_can_clean(struct net_device *net)
{
        struct m_can_classdev *cdev = netdev_priv(net);
        unsigned long irqflags;

        if (cdev->tx_ops) {
                for (int i = 0; i != cdev->tx_fifo_size; ++i) {
                        if (!cdev->tx_ops[i].skb)
                                continue;

                        net->stats.tx_errors++;
                        cdev->tx_ops[i].skb = NULL;
                }
        }

        for (int i = 0; i != cdev->can.echo_skb_max; ++i)
                can_free_echo_skb(cdev->net, i, NULL);

        netdev_reset_queue(cdev->net);

        spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
        cdev->tx_fifo_in_flight = 0;
        spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
}

/* For peripherals, pass skb to rx-offload, which will push skb from
 * napi. For non-peripherals, RX is done in napi already, so push
 * directly. timestamp is used to ensure good skb ordering in
 * rx-offload and is ignored for non-peripherals.
 */
static void m_can_receive_skb(struct m_can_classdev *cdev,
                              struct sk_buff *skb,
                              u32 timestamp)
{
        if (cdev->is_peripheral) {
                struct net_device_stats *stats = &cdev->net->stats;
                int err;

                err = can_rx_offload_queue_timestamp(&cdev->offload, skb,
                                                     timestamp);
                if (err)
                        stats->rx_fifo_errors++;
        } else {
                netif_receive_skb(skb);
        }
}

static int m_can_read_fifo(struct net_device *dev, u32 fgi)
{
        struct net_device_stats *stats = &dev->stats;
        struct m_can_classdev *cdev = netdev_priv(dev);
        struct canfd_frame *cf;
        struct sk_buff *skb;
        struct id_and_dlc fifo_header;
        u32 timestamp = 0;
        int err;

        err = m_can_fifo_read(cdev, fgi, M_CAN_FIFO_ID, &fifo_header, 2);
        if (err)
                goto out_fail;

        if (fifo_header.dlc & RX_BUF_FDF)
                skb = alloc_canfd_skb(dev, &cf);
        else
                skb = alloc_can_skb(dev, (struct can_frame **)&cf);
        if (!skb) {
                stats->rx_dropped++;
                return 0;
        }

        if (fifo_header.dlc & RX_BUF_FDF)
                cf->len = can_fd_dlc2len((fifo_header.dlc >> 16) & 0x0F);
        else
                cf->len = can_cc_dlc2len((fifo_header.dlc >> 16) & 0x0F);

        if (fifo_header.id & RX_BUF_XTD)
                cf->can_id = (fifo_header.id & CAN_EFF_MASK) | CAN_EFF_FLAG;
        else
                cf->can_id = (fifo_header.id >> 18) & CAN_SFF_MASK;

        if (fifo_header.id & RX_BUF_ESI) {
                cf->flags |= CANFD_ESI;
                netdev_dbg(dev, "ESI Error\n");
        }

        if (!(fifo_header.dlc & RX_BUF_FDF) && (fifo_header.id & RX_BUF_RTR)) {
                cf->can_id |= CAN_RTR_FLAG;
        } else {
                if (fifo_header.dlc & RX_BUF_BRS)
                        cf->flags |= CANFD_BRS;

                err = m_can_fifo_read(cdev, fgi, M_CAN_FIFO_DATA,
                                      cf->data, DIV_ROUND_UP(cf->len, 4));
                if (err)
                        goto out_free_skb;

                stats->rx_bytes += cf->len;
        }
        stats->rx_packets++;

        timestamp = FIELD_GET(RX_BUF_RXTS_MASK, fifo_header.dlc) << 16;

        m_can_receive_skb(cdev, skb, timestamp);

        return 0;

out_free_skb:
        kfree_skb(skb);
out_fail:
        netdev_err(dev, "FIFO read returned %d\n", err);
        return err;
}

static int m_can_do_rx_poll(struct net_device *dev, int quota)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        u32 pkts = 0;
        u32 rxfs;
        u32 rx_count;
        u32 fgi;
        int ack_fgi = -1;
        int i;
        int err = 0;

        rxfs = m_can_read(cdev, M_CAN_RXF0S);
        if (!(rxfs & RXFS_FFL_MASK)) {
                netdev_dbg(dev, "no messages in fifo0\n");
                return 0;
        }

        rx_count = FIELD_GET(RXFS_FFL_MASK, rxfs);
        fgi = FIELD_GET(RXFS_FGI_MASK, rxfs);

        for (i = 0; i < rx_count && quota > 0; ++i) {
                err = m_can_read_fifo(dev, fgi);
                if (err)
                        break;

                quota--;
                pkts++;
                ack_fgi = fgi;
                fgi = (++fgi >= cdev->mcfg[MRAM_RXF0].num ? 0 : fgi);
        }

        if (ack_fgi != -1)
                m_can_write(cdev, M_CAN_RXF0A, ack_fgi);

        if (err)
                return err;

        return pkts;
}

static int m_can_handle_lost_msg(struct net_device *dev)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        struct sk_buff *skb;
        struct can_frame *frame;
        u32 timestamp = 0;

        netdev_dbg(dev, "msg lost in rxf0\n");

        stats->rx_errors++;
        stats->rx_over_errors++;

        skb = alloc_can_err_skb(dev, &frame);
        if (unlikely(!skb))
                return 0;

        frame->can_id |= CAN_ERR_CRTL;
        frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;

        if (cdev->is_peripheral)
                timestamp = m_can_get_timestamp(cdev);

        m_can_receive_skb(cdev, skb, timestamp);

        return 1;
}

static int m_can_handle_lec_err(struct net_device *dev,
                                enum m_can_lec_type lec_type)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        struct can_frame *cf;
        struct sk_buff *skb;
        u32 timestamp = 0;

        cdev->can.can_stats.bus_error++;

        /* propagate the error condition to the CAN stack */
        skb = alloc_can_err_skb(dev, &cf);

        /* check for 'last error code' which tells us the
         * type of the last error to occur on the CAN bus
         */
        if (likely(skb))
                cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;

        switch (lec_type) {
        case LEC_STUFF_ERROR:
                netdev_dbg(dev, "stuff error\n");
                stats->rx_errors++;
                if (likely(skb))
                        cf->data[2] |= CAN_ERR_PROT_STUFF;
                break;
        case LEC_FORM_ERROR:
                netdev_dbg(dev, "form error\n");
                stats->rx_errors++;
                if (likely(skb))
                        cf->data[2] |= CAN_ERR_PROT_FORM;
                break;
        case LEC_ACK_ERROR:
                netdev_dbg(dev, "ack error\n");
                stats->tx_errors++;
                if (likely(skb))
                        cf->data[3] = CAN_ERR_PROT_LOC_ACK;
                break;
        case LEC_BIT1_ERROR:
                netdev_dbg(dev, "bit1 error\n");
                stats->tx_errors++;
                if (likely(skb))
                        cf->data[2] |= CAN_ERR_PROT_BIT1;
                break;
        case LEC_BIT0_ERROR:
                netdev_dbg(dev, "bit0 error\n");
                stats->tx_errors++;
                if (likely(skb))
                        cf->data[2] |= CAN_ERR_PROT_BIT0;
                break;
        case LEC_CRC_ERROR:
                netdev_dbg(dev, "CRC error\n");
                stats->rx_errors++;
                if (likely(skb))
                        cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ;
                break;
        default:
                break;
        }

        if (unlikely(!skb))
                return 0;

        if (cdev->is_peripheral)
                timestamp = m_can_get_timestamp(cdev);

        m_can_receive_skb(cdev, skb, timestamp);

        return 1;
}

static int __m_can_get_berr_counter(const struct net_device *dev,
                                    struct can_berr_counter *bec)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        unsigned int ecr;

        ecr = m_can_read(cdev, M_CAN_ECR);
        bec->rxerr = FIELD_GET(ECR_REC_MASK, ecr);
        bec->txerr = FIELD_GET(ECR_TEC_MASK, ecr);

        return 0;
}

static int m_can_clk_start(struct m_can_classdev *cdev)
{
        if (cdev->pm_clock_support == 0)
                return 0;

        return pm_runtime_resume_and_get(cdev->dev);
}

static void m_can_clk_stop(struct m_can_classdev *cdev)
{
        if (cdev->pm_clock_support)
                pm_runtime_put_sync(cdev->dev);
}

static int m_can_get_berr_counter(const struct net_device *dev,
                                  struct can_berr_counter *bec)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        int err;

        /* Avoid waking up the controller if the interface is down */
        if (!(dev->flags & IFF_UP))
                return 0;

        err = m_can_clk_start(cdev);
        if (err)
                return err;

        __m_can_get_berr_counter(dev, bec);

        m_can_clk_stop(cdev);

        return 0;
}

static int m_can_handle_state_change(struct net_device *dev,
                                     enum can_state new_state)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        struct can_frame *cf;
        struct sk_buff *skb;
        struct can_berr_counter bec;
        unsigned int ecr;
        u32 timestamp = 0;

        switch (new_state) {
        case CAN_STATE_ERROR_ACTIVE:
                cdev->can.state = CAN_STATE_ERROR_ACTIVE;
                break;
        case CAN_STATE_ERROR_WARNING:
                /* error warning state */
                cdev->can.can_stats.error_warning++;
                cdev->can.state = CAN_STATE_ERROR_WARNING;
                break;
        case CAN_STATE_ERROR_PASSIVE:
                /* error passive state */
                cdev->can.can_stats.error_passive++;
                cdev->can.state = CAN_STATE_ERROR_PASSIVE;
                break;
        case CAN_STATE_BUS_OFF:
                /* bus-off state */
                cdev->can.state = CAN_STATE_BUS_OFF;
                m_can_disable_all_interrupts(cdev);
                cdev->can.can_stats.bus_off++;
                can_bus_off(dev);
                break;
        default:
                break;
        }

        /* propagate the error condition to the CAN stack */
        skb = alloc_can_err_skb(dev, &cf);
        if (unlikely(!skb))
                return 0;

        __m_can_get_berr_counter(dev, &bec);

        switch (new_state) {
        case CAN_STATE_ERROR_ACTIVE:
                cf->can_id |= CAN_ERR_CRTL | CAN_ERR_CNT;
                cf->data[1] = CAN_ERR_CRTL_ACTIVE;
                cf->data[6] = bec.txerr;
                cf->data[7] = bec.rxerr;
                break;
        case CAN_STATE_ERROR_WARNING:
                /* error warning state */
                cf->can_id |= CAN_ERR_CRTL | CAN_ERR_CNT;
                cf->data[1] = (bec.txerr > bec.rxerr) ?
                        CAN_ERR_CRTL_TX_WARNING :
                        CAN_ERR_CRTL_RX_WARNING;
                cf->data[6] = bec.txerr;
                cf->data[7] = bec.rxerr;
                break;
        case CAN_STATE_ERROR_PASSIVE:
                /* error passive state */
                cf->can_id |= CAN_ERR_CRTL | CAN_ERR_CNT;
                ecr = m_can_read(cdev, M_CAN_ECR);
                if (ecr & ECR_RP)
                        cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
                if (bec.txerr > 127)
                        cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE;
                cf->data[6] = bec.txerr;
                cf->data[7] = bec.rxerr;
                break;
        case CAN_STATE_BUS_OFF:
                /* bus-off state */
                cf->can_id |= CAN_ERR_BUSOFF;
                break;
        default:
                break;
        }

        if (cdev->is_peripheral)
                timestamp = m_can_get_timestamp(cdev);

        m_can_receive_skb(cdev, skb, timestamp);

        return 1;
}

static enum can_state
m_can_state_get_by_psr(struct m_can_classdev *cdev)
{
        u32 reg_psr;

        reg_psr = m_can_read(cdev, M_CAN_PSR);

        if (reg_psr & PSR_BO)
                return CAN_STATE_BUS_OFF;
        if (reg_psr & PSR_EP)
                return CAN_STATE_ERROR_PASSIVE;
        if (reg_psr & PSR_EW)
                return CAN_STATE_ERROR_WARNING;

        return CAN_STATE_ERROR_ACTIVE;
}

static int m_can_handle_state_errors(struct net_device *dev)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        enum can_state new_state;

        new_state = m_can_state_get_by_psr(cdev);
        if (new_state == cdev->can.state)
                return 0;

        return m_can_handle_state_change(dev, new_state);
}

static void m_can_handle_other_err(struct net_device *dev, u32 irqstatus)
{
        if (irqstatus & IR_WDI)
                netdev_err(dev, "Message RAM Watchdog event due to missing READY\n");
        if (irqstatus & IR_BEU)
                netdev_err(dev, "Bit Error Uncorrected\n");
        if (irqstatus & IR_BEC)
                netdev_err(dev, "Bit Error Corrected\n");
        if (irqstatus & IR_TOO)
                netdev_err(dev, "Timeout reached\n");
        if (irqstatus & IR_MRAF)
                netdev_err(dev, "Message RAM access failure occurred\n");
}

static inline bool is_lec_err(u8 lec)
{
        return lec != LEC_NO_ERROR && lec != LEC_NO_CHANGE;
}

static inline bool m_can_is_protocol_err(u32 irqstatus)
{
        return irqstatus & IR_ERR_LEC_31X;
}

static int m_can_handle_protocol_error(struct net_device *dev, u32 irqstatus)
{
        struct net_device_stats *stats = &dev->stats;
        struct m_can_classdev *cdev = netdev_priv(dev);
        struct can_frame *cf;
        struct sk_buff *skb;
        u32 timestamp = 0;

        /* propagate the error condition to the CAN stack */
        skb = alloc_can_err_skb(dev, &cf);

        /* update tx error stats since there is protocol error */
        stats->tx_errors++;

        /* update arbitration lost status */
        if (cdev->version >= 31 && (irqstatus & IR_PEA)) {
                netdev_dbg(dev, "Protocol error in Arbitration fail\n");
                cdev->can.can_stats.arbitration_lost++;
                if (skb) {
                        cf->can_id |= CAN_ERR_LOSTARB;
                        cf->data[0] |= CAN_ERR_LOSTARB_UNSPEC;
                }
        }

        if (unlikely(!skb)) {
                netdev_dbg(dev, "allocation of skb failed\n");
                return 0;
        }

        if (cdev->is_peripheral)
                timestamp = m_can_get_timestamp(cdev);

        m_can_receive_skb(cdev, skb, timestamp);

        return 1;
}

static int m_can_handle_bus_errors(struct net_device *dev, u32 irqstatus,
                                   u32 psr)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        int work_done = 0;

        if (irqstatus & IR_RF0L)
                work_done += m_can_handle_lost_msg(dev);

        /* handle lec errors on the bus */
        if (cdev->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) {
                u8 lec = FIELD_GET(PSR_LEC_MASK, psr);
                u8 dlec = FIELD_GET(PSR_DLEC_MASK, psr);

                if (is_lec_err(lec)) {
                        netdev_dbg(dev, "Arbitration phase error detected\n");
                        work_done += m_can_handle_lec_err(dev, lec);
                }

                if (is_lec_err(dlec)) {
                        netdev_dbg(dev, "Data phase error detected\n");
                        work_done += m_can_handle_lec_err(dev, dlec);
                }
        }

        /* handle protocol errors in arbitration phase */
        if ((cdev->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) &&
            m_can_is_protocol_err(irqstatus))
                work_done += m_can_handle_protocol_error(dev, irqstatus);

        /* other unproccessed error interrupts */
        m_can_handle_other_err(dev, irqstatus);

        return work_done;
}

static int m_can_rx_handler(struct net_device *dev, int quota, u32 irqstatus)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        int rx_work_or_err;
        int work_done = 0;

        if (!irqstatus)
                goto end;

        /* Errata workaround for issue "Needless activation of MRAF irq"
         * During frame reception while the MCAN is in Error Passive state
         * and the Receive Error Counter has the value MCAN_ECR.REC = 127,
         * it may happen that MCAN_IR.MRAF is set although there was no
         * Message RAM access failure.
         * If MCAN_IR.MRAF is enabled, an interrupt to the Host CPU is generated
         * The Message RAM Access Failure interrupt routine needs to check
         * whether MCAN_ECR.RP = ’1’ and MCAN_ECR.REC = 127.
         * In this case, reset MCAN_IR.MRAF. No further action is required.
         */
        if (cdev->version <= 31 && irqstatus & IR_MRAF &&
            m_can_read(cdev, M_CAN_ECR) & ECR_RP) {
                struct can_berr_counter bec;

                __m_can_get_berr_counter(dev, &bec);
                if (bec.rxerr == 127) {
                        m_can_write(cdev, M_CAN_IR, IR_MRAF);
                        irqstatus &= ~IR_MRAF;
                }
        }

        if (irqstatus & IR_ERR_STATE)
                work_done += m_can_handle_state_errors(dev);

        if (irqstatus & IR_ERR_BUS_30X)
                work_done += m_can_handle_bus_errors(dev, irqstatus,
                                                     m_can_read(cdev, M_CAN_PSR));

        if (irqstatus & IR_RF0N) {
                rx_work_or_err = m_can_do_rx_poll(dev, (quota - work_done));
                if (rx_work_or_err < 0)
                        return rx_work_or_err;

                work_done += rx_work_or_err;
        }
end:
        return work_done;
}

static int m_can_poll(struct napi_struct *napi, int quota)
{
        struct net_device *dev = napi->dev;
        struct m_can_classdev *cdev = netdev_priv(dev);
        int work_done;
        u32 irqstatus;

        irqstatus = cdev->irqstatus | m_can_read(cdev, M_CAN_IR);

        work_done = m_can_rx_handler(dev, quota, irqstatus);

        /* Don't re-enable interrupts if the driver had a fatal error
         * (e.g., FIFO read failure).
         */
        if (work_done >= 0 && work_done < quota) {
                napi_complete_done(napi, work_done);
                m_can_enable_all_interrupts(cdev);
        }

        return work_done;
}

/* Echo tx skb and update net stats. Peripherals use rx-offload for
 * echo. timestamp is used for peripherals to ensure correct ordering
 * by rx-offload, and is ignored for non-peripherals.
 */
static unsigned int m_can_tx_update_stats(struct m_can_classdev *cdev,
                                          unsigned int msg_mark, u32 timestamp)
{
        struct net_device *dev = cdev->net;
        struct net_device_stats *stats = &dev->stats;
        unsigned int frame_len;

        if (cdev->is_peripheral)
                stats->tx_bytes +=
                        can_rx_offload_get_echo_skb_queue_timestamp(&cdev->offload,
                                                                    msg_mark,
                                                                    timestamp,
                                                                    &frame_len);
        else
                stats->tx_bytes += can_get_echo_skb(dev, msg_mark, &frame_len);

        stats->tx_packets++;

        return frame_len;
}

static void m_can_finish_tx(struct m_can_classdev *cdev, int transmitted,
                            unsigned int transmitted_frame_len)
{
        unsigned long irqflags;

        netdev_completed_queue(cdev->net, transmitted, transmitted_frame_len);

        spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
        if (cdev->tx_fifo_in_flight >= cdev->tx_fifo_size && transmitted > 0)
                netif_wake_queue(cdev->net);
        cdev->tx_fifo_in_flight -= transmitted;
        spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
}

static netdev_tx_t m_can_start_tx(struct m_can_classdev *cdev)
{
        unsigned long irqflags;
        int tx_fifo_in_flight;

        spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
        tx_fifo_in_flight = cdev->tx_fifo_in_flight + 1;
        if (tx_fifo_in_flight >= cdev->tx_fifo_size) {
                netif_stop_queue(cdev->net);
                if (tx_fifo_in_flight > cdev->tx_fifo_size) {
                        netdev_err_once(cdev->net, "hard_xmit called while TX FIFO full\n");
                        spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
                        return NETDEV_TX_BUSY;
                }
        }
        cdev->tx_fifo_in_flight = tx_fifo_in_flight;
        spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);

        return NETDEV_TX_OK;
}

static int m_can_echo_tx_event(struct net_device *dev)
{
        u32 txe_count = 0;
        u32 m_can_txefs;
        u32 fgi = 0;
        int ack_fgi = -1;
        int i = 0;
        int err = 0;
        unsigned int msg_mark;
        int processed = 0;
        unsigned int processed_frame_len = 0;

        struct m_can_classdev *cdev = netdev_priv(dev);

        /* read tx event fifo status */
        m_can_txefs = m_can_read(cdev, M_CAN_TXEFS);

        /* Get Tx Event fifo element count */
        txe_count = FIELD_GET(TXEFS_EFFL_MASK, m_can_txefs);
        fgi = FIELD_GET(TXEFS_EFGI_MASK, m_can_txefs);

        /* Get and process all sent elements */
        for (i = 0; i < txe_count; i++) {
                u32 txe, timestamp = 0;

                /* get message marker, timestamp */
                err = m_can_txe_fifo_read(cdev, fgi, 4, &txe);
                if (err) {
                        netdev_err(dev, "TXE FIFO read returned %d\n", err);
                        break;
                }

                msg_mark = FIELD_GET(TX_EVENT_MM_MASK, txe);
                timestamp = FIELD_GET(TX_EVENT_TXTS_MASK, txe) << 16;

                ack_fgi = fgi;
                fgi = (++fgi >= cdev->mcfg[MRAM_TXE].num ? 0 : fgi);

                /* update stats */
                processed_frame_len += m_can_tx_update_stats(cdev, msg_mark,
                                                             timestamp);

                ++processed;
        }

        if (ack_fgi != -1)
                m_can_write(cdev, M_CAN_TXEFA, FIELD_PREP(TXEFA_EFAI_MASK,
                                                          ack_fgi));

        m_can_finish_tx(cdev, processed, processed_frame_len);

        return err;
}

static void m_can_coalescing_update(struct m_can_classdev *cdev, u32 ir)
{
        u32 new_interrupts = cdev->active_interrupts;
        bool enable_rx_timer = false;
        bool enable_tx_timer = false;

        if (!cdev->net->irq)
                return;

        if (cdev->rx_coalesce_usecs_irq > 0 && (ir & (IR_RF0N | IR_RF0W))) {
                enable_rx_timer = true;
                new_interrupts &= ~IR_RF0N;
        }
        if (cdev->tx_coalesce_usecs_irq > 0 && (ir & (IR_TEFN | IR_TEFW))) {
                enable_tx_timer = true;
                new_interrupts &= ~IR_TEFN;
        }
        if (!enable_rx_timer && !hrtimer_active(&cdev->hrtimer))
                new_interrupts |= IR_RF0N;
        if (!enable_tx_timer && !hrtimer_active(&cdev->hrtimer))
                new_interrupts |= IR_TEFN;

        m_can_interrupt_enable(cdev, new_interrupts);
        if (enable_rx_timer | enable_tx_timer)
                hrtimer_start(&cdev->hrtimer, cdev->irq_timer_wait,
                              HRTIMER_MODE_REL);
}

/* This interrupt handler is called either from the interrupt thread or a
 * hrtimer. This has implications like cancelling a timer won't be possible
 * blocking.
 */
static int m_can_interrupt_handler(struct m_can_classdev *cdev)
{
        struct net_device *dev = cdev->net;
        u32 ir = 0, ir_read;
        int ret;

        if (pm_runtime_suspended(cdev->dev))
                return IRQ_NONE;

        /* The m_can controller signals its interrupt status as a level, but
         * depending in the integration the CPU may interpret the signal as
         * edge-triggered (for example with m_can_pci). For these
         * edge-triggered integrations, we must observe that IR is 0 at least
         * once to be sure that the next interrupt will generate an edge.
         */
        while ((ir_read = m_can_read(cdev, M_CAN_IR)) != 0) {
                ir |= ir_read;

                /* ACK all irqs */
                m_can_write(cdev, M_CAN_IR, ir);

                if (!cdev->irq_edge_triggered)
                        break;
        }

        m_can_coalescing_update(cdev, ir);
        if (!ir)
                return IRQ_NONE;

        if (cdev->ops->clear_interrupts)
                cdev->ops->clear_interrupts(cdev);

        /* schedule NAPI in case of
         * - rx IRQ
         * - state change IRQ
         * - bus error IRQ and bus error reporting
         */
        if (ir & (IR_RF0N | IR_RF0W | IR_ERR_ALL_30X)) {
                cdev->irqstatus = ir;
                if (!cdev->is_peripheral) {
                        m_can_disable_all_interrupts(cdev);
                        napi_schedule(&cdev->napi);
                } else {
                        ret = m_can_rx_handler(dev, NAPI_POLL_WEIGHT, ir);
                        if (ret < 0)
                                return ret;
                }
        }

        if (cdev->version == 30) {
                if (ir & IR_TC) {
                        /* Transmission Complete Interrupt*/
                        u32 timestamp = 0;
                        unsigned int frame_len;

                        if (cdev->is_peripheral)
                                timestamp = m_can_get_timestamp(cdev);
                        frame_len = m_can_tx_update_stats(cdev, 0, timestamp);
                        m_can_finish_tx(cdev, 1, frame_len);
                }
        } else  {
                if (ir & (IR_TEFN | IR_TEFW)) {
                        /* New TX FIFO Element arrived */
                        ret = m_can_echo_tx_event(dev);
                        if (ret != 0)
                                return ret;
                }
        }

        if (cdev->is_peripheral)
                can_rx_offload_threaded_irq_finish(&cdev->offload);

        return IRQ_HANDLED;
}

static irqreturn_t m_can_isr(int irq, void *dev_id)
{
        struct net_device *dev = (struct net_device *)dev_id;
        struct m_can_classdev *cdev = netdev_priv(dev);
        int ret;

        ret =  m_can_interrupt_handler(cdev);
        if (ret < 0) {
                m_can_disable_all_interrupts(cdev);
                return IRQ_HANDLED;
        }

        return ret;
}

static enum hrtimer_restart m_can_coalescing_timer(struct hrtimer *timer)
{
        struct m_can_classdev *cdev = container_of(timer, struct m_can_classdev, hrtimer);

        if (cdev->can.state == CAN_STATE_BUS_OFF ||
            cdev->can.state == CAN_STATE_STOPPED)
                return HRTIMER_NORESTART;

        irq_wake_thread(cdev->net->irq, cdev->net);

        return HRTIMER_NORESTART;
}

static const struct can_bittiming_const m_can_bittiming_const_30X = {
        .name = KBUILD_MODNAME,
        .tseg1_min = 2,         /* Time segment 1 = prop_seg + phase_seg1 */
        .tseg1_max = 64,
        .tseg2_min = 1,         /* Time segment 2 = phase_seg2 */
        .tseg2_max = 16,
        .sjw_max = 16,
        .brp_min = 1,
        .brp_max = 1024,
        .brp_inc = 1,
};

static const struct can_bittiming_const m_can_data_bittiming_const_30X = {
        .name = KBUILD_MODNAME,
        .tseg1_min = 2,         /* Time segment 1 = prop_seg + phase_seg1 */
        .tseg1_max = 16,
        .tseg2_min = 1,         /* Time segment 2 = phase_seg2 */
        .tseg2_max = 8,
        .sjw_max = 4,
        .brp_min = 1,
        .brp_max = 32,
        .brp_inc = 1,
};

static const struct can_bittiming_const m_can_bittiming_const_31X = {
        .name = KBUILD_MODNAME,
        .tseg1_min = 2,         /* Time segment 1 = prop_seg + phase_seg1 */
        .tseg1_max = 256,
        .tseg2_min = 2,         /* Time segment 2 = phase_seg2 */
        .tseg2_max = 128,
        .sjw_max = 128,
        .brp_min = 1,
        .brp_max = 512,
        .brp_inc = 1,
};

static const struct can_bittiming_const m_can_data_bittiming_const_31X = {
        .name = KBUILD_MODNAME,
        .tseg1_min = 1,         /* Time segment 1 = prop_seg + phase_seg1 */
        .tseg1_max = 32,
        .tseg2_min = 1,         /* Time segment 2 = phase_seg2 */
        .tseg2_max = 16,
        .sjw_max = 16,
        .brp_min = 1,
        .brp_max = 32,
        .brp_inc = 1,
};

static int m_can_init_ram(struct m_can_classdev *cdev)
{
        int end, i, start;
        int err = 0;

        /* initialize the entire Message RAM in use to avoid possible
         * ECC/parity checksum errors when reading an uninitialized buffer
         */
        start = cdev->mcfg[MRAM_SIDF].off;
        end = cdev->mcfg[MRAM_TXB].off +
                cdev->mcfg[MRAM_TXB].num * TXB_ELEMENT_SIZE;

        for (i = start; i < end; i += 4) {
                err = m_can_fifo_write_no_off(cdev, i, 0x0);
                if (err)
                        break;
        }

        return err;
}

static int m_can_set_bittiming(struct net_device *dev)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        const struct can_bittiming *bt = &cdev->can.bittiming;
        const struct can_bittiming *dbt = &cdev->can.fd.data_bittiming;
        u16 brp, sjw, tseg1, tseg2;
        u32 reg_btp;

        brp = bt->brp - 1;
        sjw = bt->sjw - 1;
        tseg1 = bt->prop_seg + bt->phase_seg1 - 1;
        tseg2 = bt->phase_seg2 - 1;
        reg_btp = FIELD_PREP(NBTP_NBRP_MASK, brp) |
                  FIELD_PREP(NBTP_NSJW_MASK, sjw) |
                  FIELD_PREP(NBTP_NTSEG1_MASK, tseg1) |
                  FIELD_PREP(NBTP_NTSEG2_MASK, tseg2);
        m_can_write(cdev, M_CAN_NBTP, reg_btp);

        if (cdev->can.ctrlmode & CAN_CTRLMODE_FD) {
                reg_btp = 0;
                brp = dbt->brp - 1;
                sjw = dbt->sjw - 1;
                tseg1 = dbt->prop_seg + dbt->phase_seg1 - 1;
                tseg2 = dbt->phase_seg2 - 1;

                /* TDC is only needed for bitrates beyond 2.5 MBit/s.
                 * This is mentioned in the "Bit Time Requirements for CAN FD"
                 * paper presented at the International CAN Conference 2013
                 */
                if (dbt->bitrate > 2500000) {
                        u32 tdco, ssp;

                        /* Use the same value of secondary sampling point
                         * as the data sampling point
                         */
                        ssp = dbt->sample_point;

                        /* Equation based on Bosch's M_CAN User Manual's
                         * Transmitter Delay Compensation Section
                         */
                        tdco = (cdev->can.clock.freq / 1000) *
                                ssp / dbt->bitrate;

                        /* Max valid TDCO value is 127 */
                        if (tdco > 127) {
                                netdev_warn(dev, "TDCO value of %u is beyond maximum. Using maximum possible value\n",
                                            tdco);
                                tdco = 127;
                        }

                        reg_btp |= DBTP_TDC;
                        m_can_write(cdev, M_CAN_TDCR,
                                    FIELD_PREP(TDCR_TDCO_MASK, tdco));
                }

                reg_btp |= FIELD_PREP(DBTP_DBRP_MASK, brp) |
                        FIELD_PREP(DBTP_DSJW_MASK, sjw) |
                        FIELD_PREP(DBTP_DTSEG1_MASK, tseg1) |
                        FIELD_PREP(DBTP_DTSEG2_MASK, tseg2);

                m_can_write(cdev, M_CAN_DBTP, reg_btp);
        }

        return 0;
}

/* Configure M_CAN chip:
 * - set rx buffer/fifo element size
 * - configure rx fifo
 * - accept non-matching frame into fifo 0
 * - configure tx buffer
 *              - >= v3.1.x: TX FIFO is used
 * - configure mode
 * - setup bittiming
 * - configure timestamp generation
 */
static int m_can_chip_config(struct net_device *dev)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        u32 interrupts = IR_ALL_INT;
        u32 cccr, test;
        int err;

        err = m_can_init_ram(cdev);
        if (err) {
                netdev_err(dev, "Message RAM configuration failed\n");
                return err;
        }

        /* Disable unused interrupts */
        interrupts &= ~(IR_ARA | IR_ELO | IR_DRX | IR_TEFF | IR_TFE | IR_TCF |
                        IR_HPM | IR_RF1F | IR_RF1W | IR_RF1N | IR_RF0F |
                        IR_TSW);

        err = m_can_config_enable(cdev);
        if (err)
                return err;

        /* RX Buffer/FIFO Element Size 64 bytes data field */
        m_can_write(cdev, M_CAN_RXESC,
                    FIELD_PREP(RXESC_RBDS_MASK, RXESC_64B) |
                    FIELD_PREP(RXESC_F1DS_MASK, RXESC_64B) |
                    FIELD_PREP(RXESC_F0DS_MASK, RXESC_64B));

        /* Accept Non-matching Frames Into FIFO 0 */
        m_can_write(cdev, M_CAN_GFC, 0x0);

        if (cdev->version == 30) {
                /* only support one Tx Buffer currently */
                m_can_write(cdev, M_CAN_TXBC, FIELD_PREP(TXBC_NDTB_MASK, 1) |
                            cdev->mcfg[MRAM_TXB].off);
        } else {
                /* TX FIFO is used for newer IP Core versions */
                m_can_write(cdev, M_CAN_TXBC,
                            FIELD_PREP(TXBC_TFQS_MASK,
                                       cdev->mcfg[MRAM_TXB].num) |
                            cdev->mcfg[MRAM_TXB].off);
        }

        /* support 64 bytes payload */
        m_can_write(cdev, M_CAN_TXESC,
                    FIELD_PREP(TXESC_TBDS_MASK, TXESC_TBDS_64B));

        /* TX Event FIFO */
        if (cdev->version == 30) {
                m_can_write(cdev, M_CAN_TXEFC,
                            FIELD_PREP(TXEFC_EFS_MASK, 1) |
                            cdev->mcfg[MRAM_TXE].off);
        } else {
                /* Full TX Event FIFO is used */
                m_can_write(cdev, M_CAN_TXEFC,
                            FIELD_PREP(TXEFC_EFWM_MASK,
                                       cdev->tx_max_coalesced_frames_irq) |
                            FIELD_PREP(TXEFC_EFS_MASK,
                                       cdev->mcfg[MRAM_TXE].num) |
                            cdev->mcfg[MRAM_TXE].off);
        }

        /* rx fifo configuration, blocking mode, fifo size 1 */
        m_can_write(cdev, M_CAN_RXF0C,
                    FIELD_PREP(RXFC_FWM_MASK, cdev->rx_max_coalesced_frames_irq) |
                    FIELD_PREP(RXFC_FS_MASK, cdev->mcfg[MRAM_RXF0].num) |
                    cdev->mcfg[MRAM_RXF0].off);

        m_can_write(cdev, M_CAN_RXF1C,
                    FIELD_PREP(RXFC_FS_MASK, cdev->mcfg[MRAM_RXF1].num) |
                    cdev->mcfg[MRAM_RXF1].off);

        cccr = m_can_read(cdev, M_CAN_CCCR);
        test = m_can_read(cdev, M_CAN_TEST);
        test &= ~TEST_LBCK;
        if (cdev->version == 30) {
                /* Version 3.0.x */

                cccr &= ~(CCCR_TEST | CCCR_MON | CCCR_DAR |
                          FIELD_PREP(CCCR_CMR_MASK, FIELD_MAX(CCCR_CMR_MASK)) |
                          FIELD_PREP(CCCR_CME_MASK, FIELD_MAX(CCCR_CME_MASK)));

                if (cdev->can.ctrlmode & CAN_CTRLMODE_FD)
                        cccr |= FIELD_PREP(CCCR_CME_MASK, CCCR_CME_CANFD_BRS);

        } else {
                /* Version 3.1.x or 3.2.x */
                cccr &= ~(CCCR_TEST | CCCR_MON | CCCR_BRSE | CCCR_FDOE |
                          CCCR_NISO | CCCR_DAR);

                /* Only 3.2.x has NISO Bit implemented */
                if (cdev->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
                        cccr |= CCCR_NISO;

                if (cdev->can.ctrlmode & CAN_CTRLMODE_FD)
                        cccr |= (CCCR_BRSE | CCCR_FDOE);
        }

        /* Loopback Mode */
        if (cdev->can.ctrlmode & CAN_CTRLMODE_LOOPBACK) {
                cccr |= CCCR_TEST | CCCR_MON;
                test |= TEST_LBCK;
        }

        /* Enable Monitoring (all versions) */
        if (cdev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
                cccr |= CCCR_MON;

        /* Disable Auto Retransmission (all versions) */
        if (cdev->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
                cccr |= CCCR_DAR;

        /* Write config */
        m_can_write(cdev, M_CAN_CCCR, cccr);
        m_can_write(cdev, M_CAN_TEST, test);

        /* Enable interrupts */
        if (!(cdev->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)) {
                if (cdev->version == 30)
                        interrupts &= ~(IR_ERR_LEC_30X);
                else
                        interrupts &= ~(IR_ERR_LEC_31X);
        }
        cdev->active_interrupts = 0;
        m_can_interrupt_enable(cdev, interrupts);

        /* route all interrupts to INT0 */
        m_can_write(cdev, M_CAN_ILS, ILS_ALL_INT0);

        /* set bittiming params */
        m_can_set_bittiming(dev);

        /* enable internal timestamp generation, with a prescaler of 16. The
         * prescaler is applied to the nominal bit timing
         */
        m_can_write(cdev, M_CAN_TSCC,
                    FIELD_PREP(TSCC_TCP_MASK, 0xf) |
                    FIELD_PREP(TSCC_TSS_MASK, TSCC_TSS_INTERNAL));

        err = m_can_config_disable(cdev);
        if (err)
                return err;

        if (cdev->ops->init)
                cdev->ops->init(cdev);

        return 0;
}

static int m_can_start(struct net_device *dev)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        int ret;

        /* basic m_can configuration */
        ret = m_can_chip_config(dev);
        if (ret)
                return ret;

        netdev_queue_set_dql_min_limit(netdev_get_tx_queue(cdev->net, 0),
                                       cdev->tx_max_coalesced_frames);

        cdev->can.state = m_can_state_get_by_psr(cdev);

        m_can_enable_all_interrupts(cdev);

        if (cdev->version > 30)
                cdev->tx_fifo_putidx = FIELD_GET(TXFQS_TFQPI_MASK,
                                                 m_can_read(cdev, M_CAN_TXFQS));

        ret = m_can_cccr_update_bits(cdev, CCCR_INIT, 0);
        if (ret)
                netdev_err(dev, "failed to enter normal mode\n");

        return ret;
}

static int m_can_set_mode(struct net_device *dev, enum can_mode mode)
{
        switch (mode) {
        case CAN_MODE_START:
                m_can_clean(dev);
                m_can_start(dev);
                netif_wake_queue(dev);
                break;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

/* Checks core release number of M_CAN
 * returns 0 if an unsupported device is detected
 * else it returns the release and step coded as:
 * return value = 10 * <release> + 1 * <step>
 */
static int m_can_check_core_release(struct m_can_classdev *cdev)
{
        u32 crel_reg;
        u8 rel;
        u8 step;
        int res;

        /* Read Core Release Version and split into version number
         * Example: Version 3.2.1 => rel = 3; step = 2; substep = 1;
         */
        crel_reg = m_can_read(cdev, M_CAN_CREL);
        rel = (u8)FIELD_GET(CREL_REL_MASK, crel_reg);
        step = (u8)FIELD_GET(CREL_STEP_MASK, crel_reg);

        if (rel == 3) {
                /* M_CAN v3.x.y: create return value */
                res = 30 + step;
        } else {
                /* Unsupported M_CAN version */
                res = 0;
        }

        return res;
}

/* Selectable Non ISO support only in version 3.2.x
 * Return 1 if the bit is writable, 0 if it is not, or negative on error.
 */
static int m_can_niso_supported(struct m_can_classdev *cdev)
{
        int ret, niso;

        ret = m_can_config_enable(cdev);
        if (ret)
                return ret;

        /* First try to set the NISO bit. */
        niso = m_can_cccr_update_bits(cdev, CCCR_NISO, CCCR_NISO);

        /* Then clear the it again. */
        ret = m_can_cccr_update_bits(cdev, CCCR_NISO, 0);
        if (ret) {
                netdev_err(cdev->net, "failed to revert the NON-ISO bit in CCCR\n");
                return ret;
        }

        ret = m_can_config_disable(cdev);
        if (ret)
                return ret;

        return niso == 0;
}

static int m_can_dev_setup(struct m_can_classdev *cdev)
{
        struct net_device *dev = cdev->net;
        int m_can_version, err, niso;

        m_can_version = m_can_check_core_release(cdev);
        /* return if unsupported version */
        if (!m_can_version) {
                netdev_err(cdev->net, "Unsupported version number: %2d",
                           m_can_version);
                return -EINVAL;
        }

        /* Write the INIT bit, in case no hardware reset has happened before
         * the probe (for example, it was observed that the Intel Elkhart Lake
         * SoCs do not properly reset the CAN controllers on reboot)
         */
        err = m_can_cccr_update_bits(cdev, CCCR_INIT, CCCR_INIT);
        if (err)
                return err;

        if (!cdev->is_peripheral)
                netif_napi_add(dev, &cdev->napi, m_can_poll);

        /* Shared properties of all M_CAN versions */
        cdev->version = m_can_version;
        cdev->can.do_set_mode = m_can_set_mode;
        cdev->can.do_get_berr_counter = m_can_get_berr_counter;

        /* Set M_CAN supported operations */
        cdev->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
                CAN_CTRLMODE_LISTENONLY |
                CAN_CTRLMODE_BERR_REPORTING |
                CAN_CTRLMODE_FD |
                CAN_CTRLMODE_ONE_SHOT;

        /* Set properties depending on M_CAN version */
        switch (cdev->version) {
        case 30:
                /* CAN_CTRLMODE_FD_NON_ISO is fixed with M_CAN IP v3.0.x */
                err = can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD_NON_ISO);
                if (err)
                        return err;
                cdev->can.bittiming_const = &m_can_bittiming_const_30X;
                cdev->can.fd.data_bittiming_const = &m_can_data_bittiming_const_30X;
                break;
        case 31:
                /* CAN_CTRLMODE_FD_NON_ISO is fixed with M_CAN IP v3.1.x */
                err = can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD_NON_ISO);
                if (err)
                        return err;
                cdev->can.bittiming_const = &m_can_bittiming_const_31X;
                cdev->can.fd.data_bittiming_const = &m_can_data_bittiming_const_31X;
                break;
        case 32:
        case 33:
                /* Support both MCAN version v3.2.x and v3.3.0 */
                cdev->can.bittiming_const = &m_can_bittiming_const_31X;
                cdev->can.fd.data_bittiming_const = &m_can_data_bittiming_const_31X;

                niso = m_can_niso_supported(cdev);
                if (niso < 0)
                        return niso;
                if (niso)
                        cdev->can.ctrlmode_supported |= CAN_CTRLMODE_FD_NON_ISO;
                break;
        default:
                netdev_err(cdev->net, "Unsupported version number: %2d",
                           cdev->version);
                return -EINVAL;
        }

        return 0;
}

static void m_can_stop(struct net_device *dev)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        int ret;

        /* disable all interrupts */
        m_can_disable_all_interrupts(cdev);

        /* Set init mode to disengage from the network */
        ret = m_can_cccr_update_bits(cdev, CCCR_INIT, CCCR_INIT);
        if (ret)
                netdev_err(dev, "failed to enter standby mode: %pe\n",
                           ERR_PTR(ret));

        /* set the state as STOPPED */
        cdev->can.state = CAN_STATE_STOPPED;

        if (cdev->ops->deinit) {
                ret = cdev->ops->deinit(cdev);
                if (ret)
                        netdev_err(dev, "failed to deinitialize: %pe\n",
                                   ERR_PTR(ret));
        }
}

static int m_can_close(struct net_device *dev)
{
        struct m_can_classdev *cdev = netdev_priv(dev);

        netif_stop_queue(dev);

        m_can_stop(dev);
        if (dev->irq)
                free_irq(dev->irq, dev);

        m_can_clean(dev);

        if (cdev->is_peripheral) {
                destroy_workqueue(cdev->tx_wq);
                cdev->tx_wq = NULL;
                can_rx_offload_disable(&cdev->offload);
        } else {
                napi_disable(&cdev->napi);
        }

        close_candev(dev);

        reset_control_assert(cdev->rst);
        m_can_clk_stop(cdev);
        phy_power_off(cdev->transceiver);

        return 0;
}

static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
                                    struct sk_buff *skb)
{
        struct canfd_frame *cf = (struct canfd_frame *)skb->data;
        u8 len_padded = DIV_ROUND_UP(cf->len, 4);
        struct m_can_fifo_element fifo_element;
        struct net_device *dev = cdev->net;
        u32 cccr, fdflags;
        int err;
        u32 putidx;
        unsigned int frame_len = can_skb_get_frame_len(skb);

        /* Generate ID field for TX buffer Element */
        /* Common to all supported M_CAN versions */
        if (cf->can_id & CAN_EFF_FLAG) {
                fifo_element.id = cf->can_id & CAN_EFF_MASK;
                fifo_element.id |= TX_BUF_XTD;
        } else {
                fifo_element.id = ((cf->can_id & CAN_SFF_MASK) << 18);
        }

        if (cf->can_id & CAN_RTR_FLAG)
                fifo_element.id |= TX_BUF_RTR;

        if (cdev->version == 30) {
                netif_stop_queue(dev);

                fifo_element.dlc = can_fd_len2dlc(cf->len) << 16;

                /* Write the frame ID, DLC, and payload to the FIFO element. */
                err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_ID, &fifo_element, 2);
                if (err)
                        goto out_fail;

                err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_DATA,
                                       cf->data, len_padded);
                if (err)
                        goto out_fail;

                if (cdev->can.ctrlmode & CAN_CTRLMODE_FD) {
                        cccr = m_can_read(cdev, M_CAN_CCCR);
                        cccr &= ~CCCR_CMR_MASK;
                        if (can_is_canfd_skb(skb)) {
                                if (cf->flags & CANFD_BRS)
                                        cccr |= FIELD_PREP(CCCR_CMR_MASK,
                                                           CCCR_CMR_CANFD_BRS);
                                else
                                        cccr |= FIELD_PREP(CCCR_CMR_MASK,
                                                           CCCR_CMR_CANFD);
                        } else {
                                cccr |= FIELD_PREP(CCCR_CMR_MASK, CCCR_CMR_CAN);
                        }
                        m_can_write(cdev, M_CAN_CCCR, cccr);
                }
                m_can_write(cdev, M_CAN_TXBTIE, 0x1);

                can_put_echo_skb(skb, dev, 0, frame_len);

                m_can_write(cdev, M_CAN_TXBAR, 0x1);
                /* End of xmit function for version 3.0.x */
        } else {
                /* Transmit routine for version >= v3.1.x */

                /* get put index for frame */
                putidx = cdev->tx_fifo_putidx;

                /* Construct DLC Field, with CAN-FD configuration.
                 * Use the put index of the fifo as the message marker,
                 * used in the TX interrupt for sending the correct echo frame.
                 */

                /* get CAN FD configuration of frame */
                fdflags = 0;
                if (can_is_canfd_skb(skb)) {
                        fdflags |= TX_BUF_FDF;
                        if (cf->flags & CANFD_BRS)
                                fdflags |= TX_BUF_BRS;
                }

                fifo_element.dlc = FIELD_PREP(TX_BUF_MM_MASK, putidx) |
                        FIELD_PREP(TX_BUF_DLC_MASK, can_fd_len2dlc(cf->len)) |
                        fdflags | TX_BUF_EFC;

                memcpy_and_pad(fifo_element.data, CANFD_MAX_DLEN, &cf->data,
                               cf->len, 0);

                err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID,
                                       &fifo_element, 2 + len_padded);
                if (err)
                        goto out_fail;

                /* Push loopback echo.
                 * Will be looped back on TX interrupt based on message marker
                 */
                can_put_echo_skb(skb, dev, putidx, frame_len);

                if (cdev->is_peripheral) {
                        /* Delay enabling TX FIFO element */
                        cdev->tx_peripheral_submit |= BIT(putidx);
                } else {
                        /* Enable TX FIFO element to start transfer  */
                        m_can_write(cdev, M_CAN_TXBAR, BIT(putidx));
                }
                cdev->tx_fifo_putidx = (++cdev->tx_fifo_putidx >= cdev->can.echo_skb_max ?
                                        0 : cdev->tx_fifo_putidx);
        }

        return NETDEV_TX_OK;

out_fail:
        netdev_err(dev, "FIFO write returned %d\n", err);
        m_can_disable_all_interrupts(cdev);
        return NETDEV_TX_BUSY;
}

static void m_can_tx_submit(struct m_can_classdev *cdev)
{
        m_can_write(cdev, M_CAN_TXBAR, cdev->tx_peripheral_submit);
        cdev->tx_peripheral_submit = 0;
}

static void m_can_tx_work_queue(struct work_struct *ws)
{
        struct m_can_tx_op *op = container_of(ws, struct m_can_tx_op, work);
        struct m_can_classdev *cdev = op->cdev;
        struct sk_buff *skb = op->skb;

        op->skb = NULL;
        m_can_tx_handler(cdev, skb);
        if (op->submit)
                m_can_tx_submit(cdev);
}

static void m_can_tx_queue_skb(struct m_can_classdev *cdev, struct sk_buff *skb,
                               bool submit)
{
        cdev->tx_ops[cdev->next_tx_op].skb = skb;
        cdev->tx_ops[cdev->next_tx_op].submit = submit;
        queue_work(cdev->tx_wq, &cdev->tx_ops[cdev->next_tx_op].work);

        ++cdev->next_tx_op;
        if (cdev->next_tx_op >= cdev->tx_fifo_size)
                cdev->next_tx_op = 0;
}

static netdev_tx_t m_can_start_peripheral_xmit(struct m_can_classdev *cdev,
                                               struct sk_buff *skb)
{
        bool submit;

        ++cdev->nr_txs_without_submit;
        if (cdev->nr_txs_without_submit >= cdev->tx_max_coalesced_frames ||
            !netdev_xmit_more()) {
                cdev->nr_txs_without_submit = 0;
                submit = true;
        } else {
                submit = false;
        }
        m_can_tx_queue_skb(cdev, skb, submit);

        return NETDEV_TX_OK;
}

static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
                                    struct net_device *dev)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        unsigned int frame_len;
        netdev_tx_t ret;

        if (can_dev_dropped_skb(dev, skb))
                return NETDEV_TX_OK;

        frame_len = can_skb_get_frame_len(skb);

        if (cdev->can.state == CAN_STATE_BUS_OFF) {
                m_can_clean(cdev->net);
                return NETDEV_TX_OK;
        }

        ret = m_can_start_tx(cdev);
        if (ret != NETDEV_TX_OK)
                return ret;

        netdev_sent_queue(dev, frame_len);

        if (cdev->is_peripheral)
                ret = m_can_start_peripheral_xmit(cdev, skb);
        else
                ret = m_can_tx_handler(cdev, skb);

        if (ret != NETDEV_TX_OK)
                netdev_completed_queue(dev, 1, frame_len);

        return ret;
}

static enum hrtimer_restart m_can_polling_timer(struct hrtimer *timer)
{
        struct m_can_classdev *cdev = container_of(timer, struct
                                                   m_can_classdev, hrtimer);
        int ret;

        if (cdev->can.state == CAN_STATE_BUS_OFF ||
            cdev->can.state == CAN_STATE_STOPPED)
                return HRTIMER_NORESTART;

        ret = m_can_interrupt_handler(cdev);

        /* On error or if napi is scheduled to read, stop the timer */
        if (ret < 0 || napi_is_scheduled(&cdev->napi))
                return HRTIMER_NORESTART;

        hrtimer_forward_now(timer, ms_to_ktime(HRTIMER_POLL_INTERVAL_MS));

        return HRTIMER_RESTART;
}

static int m_can_open(struct net_device *dev)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        int err;

        err = phy_power_on(cdev->transceiver);
        if (err)
                return err;

        err = m_can_clk_start(cdev);
        if (err)
                goto out_phy_power_off;

        err = reset_control_deassert(cdev->rst);
        if (err)
                goto exit_disable_clks;

        /* open the can device */
        err = open_candev(dev);
        if (err) {
                netdev_err(dev, "failed to open can device\n");
                goto out_reset_control_assert;
        }

        if (cdev->is_peripheral)
                can_rx_offload_enable(&cdev->offload);
        else
                napi_enable(&cdev->napi);

        /* register interrupt handler */
        if (cdev->is_peripheral) {
                cdev->tx_wq = alloc_ordered_workqueue("mcan_wq",
                                                      WQ_FREEZABLE | WQ_MEM_RECLAIM);
                if (!cdev->tx_wq) {
                        err = -ENOMEM;
                        goto out_wq_fail;
                }

                for (int i = 0; i != cdev->tx_fifo_size; ++i) {
                        cdev->tx_ops[i].cdev = cdev;
                        INIT_WORK(&cdev->tx_ops[i].work, m_can_tx_work_queue);
                }

                err = request_threaded_irq(dev->irq, NULL, m_can_isr,
                                           IRQF_ONESHOT,
                                           dev->name, dev);
        } else if (dev->irq) {
                err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
                                  dev);
        }

        if (err < 0) {
                netdev_err(dev, "failed to request interrupt\n");
                goto exit_irq_fail;
        }

        /* start the m_can controller */
        err = m_can_start(dev);
        if (err)
                goto exit_start_fail;

        netif_start_queue(dev);

        return 0;

exit_start_fail:
        if (cdev->is_peripheral || dev->irq)
                free_irq(dev->irq, dev);
exit_irq_fail:
        if (cdev->is_peripheral)
                destroy_workqueue(cdev->tx_wq);
out_wq_fail:
        if (cdev->is_peripheral)
                can_rx_offload_disable(&cdev->offload);
        else
                napi_disable(&cdev->napi);
        close_candev(dev);
out_reset_control_assert:
        reset_control_assert(cdev->rst);
exit_disable_clks:
        m_can_clk_stop(cdev);
out_phy_power_off:
        phy_power_off(cdev->transceiver);
        return err;
}

static const struct net_device_ops m_can_netdev_ops = {
        .ndo_open = m_can_open,
        .ndo_stop = m_can_close,
        .ndo_start_xmit = m_can_start_xmit,
};

static int m_can_get_coalesce(struct net_device *dev,
                              struct ethtool_coalesce *ec,
                              struct kernel_ethtool_coalesce *kec,
                              struct netlink_ext_ack *ext_ack)
{
        struct m_can_classdev *cdev = netdev_priv(dev);

        ec->rx_max_coalesced_frames_irq = cdev->rx_max_coalesced_frames_irq;
        ec->rx_coalesce_usecs_irq = cdev->rx_coalesce_usecs_irq;
        ec->tx_max_coalesced_frames = cdev->tx_max_coalesced_frames;
        ec->tx_max_coalesced_frames_irq = cdev->tx_max_coalesced_frames_irq;
        ec->tx_coalesce_usecs_irq = cdev->tx_coalesce_usecs_irq;

        return 0;
}

static int m_can_set_coalesce(struct net_device *dev,
                              struct ethtool_coalesce *ec,
                              struct kernel_ethtool_coalesce *kec,
                              struct netlink_ext_ack *ext_ack)
{
        struct m_can_classdev *cdev = netdev_priv(dev);

        if (cdev->can.state != CAN_STATE_STOPPED) {
                netdev_err(dev, "Device is in use, please shut it down first\n");
                return -EBUSY;
        }

        if (ec->rx_max_coalesced_frames_irq > cdev->mcfg[MRAM_RXF0].num) {
                netdev_err(dev, "rx-frames-irq %u greater than the RX FIFO %u\n",
                           ec->rx_max_coalesced_frames_irq,
                           cdev->mcfg[MRAM_RXF0].num);
                return -EINVAL;
        }
        if ((ec->rx_max_coalesced_frames_irq == 0) != (ec->rx_coalesce_usecs_irq == 0)) {
                netdev_err(dev, "rx-frames-irq and rx-usecs-irq can only be set together\n");
                return -EINVAL;
        }
        if (ec->tx_max_coalesced_frames_irq > cdev->mcfg[MRAM_TXE].num) {
                netdev_err(dev, "tx-frames-irq %u greater than the TX event FIFO %u\n",
                           ec->tx_max_coalesced_frames_irq,
                           cdev->mcfg[MRAM_TXE].num);
                return -EINVAL;
        }
        if (ec->tx_max_coalesced_frames_irq > cdev->mcfg[MRAM_TXB].num) {
                netdev_err(dev, "tx-frames-irq %u greater than the TX FIFO %u\n",
                           ec->tx_max_coalesced_frames_irq,
                           cdev->mcfg[MRAM_TXB].num);
                return -EINVAL;
        }
        if ((ec->tx_max_coalesced_frames_irq == 0) != (ec->tx_coalesce_usecs_irq == 0)) {
                netdev_err(dev, "tx-frames-irq and tx-usecs-irq can only be set together\n");
                return -EINVAL;
        }
        if (ec->tx_max_coalesced_frames > cdev->mcfg[MRAM_TXE].num) {
                netdev_err(dev, "tx-frames %u greater than the TX event FIFO %u\n",
                           ec->tx_max_coalesced_frames,
                           cdev->mcfg[MRAM_TXE].num);
                return -EINVAL;
        }
        if (ec->tx_max_coalesced_frames > cdev->mcfg[MRAM_TXB].num) {
                netdev_err(dev, "tx-frames %u greater than the TX FIFO %u\n",
                           ec->tx_max_coalesced_frames,
                           cdev->mcfg[MRAM_TXB].num);
                return -EINVAL;
        }
        if (ec->rx_coalesce_usecs_irq != 0 && ec->tx_coalesce_usecs_irq != 0 &&
            ec->rx_coalesce_usecs_irq != ec->tx_coalesce_usecs_irq) {
                netdev_err(dev, "rx-usecs-irq %u needs to be equal to tx-usecs-irq %u if both are enabled\n",
                           ec->rx_coalesce_usecs_irq,
                           ec->tx_coalesce_usecs_irq);
                return -EINVAL;
        }

        cdev->rx_max_coalesced_frames_irq = ec->rx_max_coalesced_frames_irq;
        cdev->rx_coalesce_usecs_irq = ec->rx_coalesce_usecs_irq;
        cdev->tx_max_coalesced_frames = ec->tx_max_coalesced_frames;
        cdev->tx_max_coalesced_frames_irq = ec->tx_max_coalesced_frames_irq;
        cdev->tx_coalesce_usecs_irq = ec->tx_coalesce_usecs_irq;

        if (cdev->rx_coalesce_usecs_irq)
                cdev->irq_timer_wait = us_to_ktime(cdev->rx_coalesce_usecs_irq);
        else
                cdev->irq_timer_wait = us_to_ktime(cdev->tx_coalesce_usecs_irq);

        return 0;
}

static void m_can_get_wol(struct net_device *dev, struct ethtool_wolinfo *wol)
{
        struct m_can_classdev *cdev = netdev_priv(dev);

        wol->supported = device_can_wakeup(cdev->dev) ? WAKE_PHY : 0;
        wol->wolopts = device_may_wakeup(cdev->dev) ? WAKE_PHY : 0;
}

static int m_can_set_wol(struct net_device *dev, struct ethtool_wolinfo *wol)
{
        struct m_can_classdev *cdev = netdev_priv(dev);
        bool wol_enable = !!(wol->wolopts & WAKE_PHY);
        int ret;

        if (wol->wolopts & ~WAKE_PHY)
                return -EINVAL;

        if (wol_enable == device_may_wakeup(cdev->dev))
                return 0;

        ret = device_set_wakeup_enable(cdev->dev, wol_enable);
        if (ret) {
                netdev_err(cdev->net, "Failed to set wakeup enable %pE\n",
                           ERR_PTR(ret));
                return ret;
        }

        if (!IS_ERR_OR_NULL(cdev->pinctrl_state_wakeup)) {
                if (wol_enable)
                        ret = pinctrl_select_state(cdev->pinctrl, cdev->pinctrl_state_wakeup);
                else
                        ret = pinctrl_pm_select_default_state(cdev->dev);

                if (ret) {
                        netdev_err(cdev->net, "Failed to select pinctrl state %pE\n",
                                   ERR_PTR(ret));
                        goto err_wakeup_enable;
                }
        }

        return 0;

err_wakeup_enable:
        /* Revert wakeup enable */
        device_set_wakeup_enable(cdev->dev, !wol_enable);

        return ret;
}

static const struct ethtool_ops m_can_ethtool_ops_coalescing = {
        .supported_coalesce_params = ETHTOOL_COALESCE_RX_USECS_IRQ |
                ETHTOOL_COALESCE_RX_MAX_FRAMES_IRQ |
                ETHTOOL_COALESCE_TX_USECS_IRQ |
                ETHTOOL_COALESCE_TX_MAX_FRAMES |
                ETHTOOL_COALESCE_TX_MAX_FRAMES_IRQ,
        .get_ts_info = ethtool_op_get_ts_info,
        .get_coalesce = m_can_get_coalesce,
        .set_coalesce = m_can_set_coalesce,
        .get_wol = m_can_get_wol,
        .set_wol = m_can_set_wol,
};

static const struct ethtool_ops m_can_ethtool_ops = {
        .get_ts_info = ethtool_op_get_ts_info,
        .get_wol = m_can_get_wol,
        .set_wol = m_can_set_wol,
};

static int register_m_can_dev(struct m_can_classdev *cdev)
{
        struct net_device *dev = cdev->net;

        dev->flags |= IFF_ECHO; /* we support local echo */
        dev->netdev_ops = &m_can_netdev_ops;
        if (dev->irq && cdev->is_peripheral)
                dev->ethtool_ops = &m_can_ethtool_ops_coalescing;
        else
                dev->ethtool_ops = &m_can_ethtool_ops;

        return register_candev(dev);
}

int m_can_check_mram_cfg(struct m_can_classdev *cdev, u32 mram_max_size)
{
        u32 total_size;

        total_size = cdev->mcfg[MRAM_TXB].off - cdev->mcfg[MRAM_SIDF].off +
                        cdev->mcfg[MRAM_TXB].num * TXB_ELEMENT_SIZE;
        if (total_size > mram_max_size) {
                netdev_err(cdev->net, "Total size of mram config(%u) exceeds mram(%u)\n",
                           total_size, mram_max_size);
                return -EINVAL;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(m_can_check_mram_cfg);

static void m_can_of_parse_mram(struct m_can_classdev *cdev,
                                const u32 *mram_config_vals)
{
        cdev->mcfg[MRAM_SIDF].off = mram_config_vals[0];
        cdev->mcfg[MRAM_SIDF].num = mram_config_vals[1];
        cdev->mcfg[MRAM_XIDF].off = cdev->mcfg[MRAM_SIDF].off +
                cdev->mcfg[MRAM_SIDF].num * SIDF_ELEMENT_SIZE;
        cdev->mcfg[MRAM_XIDF].num = mram_config_vals[2];
        cdev->mcfg[MRAM_RXF0].off = cdev->mcfg[MRAM_XIDF].off +
                cdev->mcfg[MRAM_XIDF].num * XIDF_ELEMENT_SIZE;
        cdev->mcfg[MRAM_RXF0].num = mram_config_vals[3] &
                FIELD_MAX(RXFC_FS_MASK);
        cdev->mcfg[MRAM_RXF1].off = cdev->mcfg[MRAM_RXF0].off +
                cdev->mcfg[MRAM_RXF0].num * RXF0_ELEMENT_SIZE;
        cdev->mcfg[MRAM_RXF1].num = mram_config_vals[4] &
                FIELD_MAX(RXFC_FS_MASK);
        cdev->mcfg[MRAM_RXB].off = cdev->mcfg[MRAM_RXF1].off +
                cdev->mcfg[MRAM_RXF1].num * RXF1_ELEMENT_SIZE;
        cdev->mcfg[MRAM_RXB].num = mram_config_vals[5];
        cdev->mcfg[MRAM_TXE].off = cdev->mcfg[MRAM_RXB].off +
                cdev->mcfg[MRAM_RXB].num * RXB_ELEMENT_SIZE;
        cdev->mcfg[MRAM_TXE].num = mram_config_vals[6];
        cdev->mcfg[MRAM_TXB].off = cdev->mcfg[MRAM_TXE].off +
                cdev->mcfg[MRAM_TXE].num * TXE_ELEMENT_SIZE;
        cdev->mcfg[MRAM_TXB].num = mram_config_vals[7] &
                FIELD_MAX(TXBC_NDTB_MASK);

        netdev_dbg(cdev->net,
                   "sidf 0x%x %d xidf 0x%x %d rxf0 0x%x %d rxf1 0x%x %d rxb 0x%x %d txe 0x%x %d txb 0x%x %d\n",
                   cdev->mcfg[MRAM_SIDF].off, cdev->mcfg[MRAM_SIDF].num,
                   cdev->mcfg[MRAM_XIDF].off, cdev->mcfg[MRAM_XIDF].num,
                   cdev->mcfg[MRAM_RXF0].off, cdev->mcfg[MRAM_RXF0].num,
                   cdev->mcfg[MRAM_RXF1].off, cdev->mcfg[MRAM_RXF1].num,
                   cdev->mcfg[MRAM_RXB].off, cdev->mcfg[MRAM_RXB].num,
                   cdev->mcfg[MRAM_TXE].off, cdev->mcfg[MRAM_TXE].num,
                   cdev->mcfg[MRAM_TXB].off, cdev->mcfg[MRAM_TXB].num);
}

int m_can_class_get_clocks(struct m_can_classdev *cdev)
{
        int ret = 0;

        cdev->hclk = devm_clk_get(cdev->dev, "hclk");
        cdev->cclk = devm_clk_get(cdev->dev, "cclk");

        if (IS_ERR(cdev->hclk) || IS_ERR(cdev->cclk)) {
                netdev_err(cdev->net, "no clock found\n");
                ret = -ENODEV;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(m_can_class_get_clocks);

static bool m_can_class_wakeup_pinctrl_enabled(struct m_can_classdev *class_dev)
{
        return device_may_wakeup(class_dev->dev) && class_dev->pinctrl_state_wakeup;
}

static int m_can_class_parse_pinctrl(struct m_can_classdev *class_dev)
{
        struct device *dev = class_dev->dev;
        int ret;

        class_dev->pinctrl = devm_pinctrl_get(dev);
        if (IS_ERR(class_dev->pinctrl)) {
                ret = PTR_ERR(class_dev->pinctrl);
                class_dev->pinctrl = NULL;

                if (ret == -ENODEV)
                        return 0;

                return dev_err_probe(dev, ret, "Failed to get pinctrl\n");
        }

        class_dev->pinctrl_state_wakeup =
                pinctrl_lookup_state(class_dev->pinctrl, "wakeup");
        if (IS_ERR(class_dev->pinctrl_state_wakeup)) {
                ret = PTR_ERR(class_dev->pinctrl_state_wakeup);
                class_dev->pinctrl_state_wakeup = NULL;

                if (ret == -ENODEV)
                        return 0;

                return dev_err_probe(dev, ret, "Failed to lookup pinctrl wakeup state\n");
        }

        return 0;
}

struct m_can_classdev *m_can_class_allocate_dev(struct device *dev,
                                                int sizeof_priv)
{
        struct m_can_classdev *class_dev = NULL;
        u32 mram_config_vals[MRAM_CFG_LEN];
        struct net_device *net_dev;
        u32 tx_fifo_size;
        int ret;

        ret = fwnode_property_read_u32_array(dev_fwnode(dev),
                                             "bosch,mram-cfg",
                                             mram_config_vals,
                                             sizeof(mram_config_vals) / 4);
        if (ret) {
                dev_err(dev, "Could not get Message RAM configuration.");
                return ERR_PTR(ret);
        }

        if (dev->of_node && of_property_read_bool(dev->of_node, "wakeup-source"))
                device_set_wakeup_capable(dev, true);

        /* Get TX FIFO size
         * Defines the total amount of echo buffers for loopback
         */
        tx_fifo_size = mram_config_vals[7];

        /* allocate the m_can device */
        net_dev = alloc_candev(sizeof_priv, tx_fifo_size);
        if (!net_dev) {
                dev_err(dev, "Failed to allocate CAN device");
                return ERR_PTR(-ENOMEM);
        }

        class_dev = netdev_priv(net_dev);
        class_dev->net = net_dev;
        class_dev->dev = dev;
        SET_NETDEV_DEV(net_dev, dev);

        m_can_of_parse_mram(class_dev, mram_config_vals);
        spin_lock_init(&class_dev->tx_handling_spinlock);

        ret = m_can_class_parse_pinctrl(class_dev);
        if (ret)
                goto err_free_candev;

        return class_dev;

err_free_candev:
        free_candev(net_dev);
        return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(m_can_class_allocate_dev);

void m_can_class_free_dev(struct net_device *net)
{
        free_candev(net);
}
EXPORT_SYMBOL_GPL(m_can_class_free_dev);

int m_can_class_register(struct m_can_classdev *cdev)
{
        int ret;

        cdev->tx_fifo_size = max(1, min(cdev->mcfg[MRAM_TXB].num,
                                        cdev->mcfg[MRAM_TXE].num));
        if (cdev->is_peripheral) {
                cdev->tx_ops =
                        devm_kzalloc(cdev->dev,
                                     cdev->tx_fifo_size * sizeof(*cdev->tx_ops),
                                     GFP_KERNEL);
                if (!cdev->tx_ops)
                        return -ENOMEM;
        }

        cdev->rst = devm_reset_control_get_optional_shared(cdev->dev, NULL);
        if (IS_ERR(cdev->rst))
                return dev_err_probe(cdev->dev, PTR_ERR(cdev->rst),
                                     "Failed to get reset line\n");

        ret = m_can_clk_start(cdev);
        if (ret)
                return ret;

        ret = reset_control_deassert(cdev->rst);
        if (ret)
                goto clk_disable;

        if (cdev->is_peripheral) {
                ret = can_rx_offload_add_manual(cdev->net, &cdev->offload,
                                                NAPI_POLL_WEIGHT);
                if (ret)
                        goto out_reset_control_assert;
        }

        if (!cdev->net->irq) {
                netdev_dbg(cdev->net, "Polling enabled, initialize hrtimer");
                hrtimer_setup(&cdev->hrtimer, m_can_polling_timer, CLOCK_MONOTONIC,
                              HRTIMER_MODE_REL_PINNED);
        } else {
                hrtimer_setup(&cdev->hrtimer, m_can_coalescing_timer, CLOCK_MONOTONIC,
                              HRTIMER_MODE_REL);
        }

        ret = m_can_dev_setup(cdev);
        if (ret)
                goto rx_offload_del;

        ret = register_m_can_dev(cdev);
        if (ret) {
                netdev_err(cdev->net, "registering %s failed (err=%d)\n",
                           cdev->net->name, ret);
                goto rx_offload_del;
        }

        of_can_transceiver(cdev->net);

        netdev_info(cdev->net, "device registered (irq=%d, version=%d)\n",
                    cdev->net->irq, cdev->version);

        /* Probe finished
         * Assert reset and stop clocks.
         * They will be reactivated once the M_CAN device is opened
         */
        reset_control_assert(cdev->rst);
        m_can_clk_stop(cdev);

        return 0;

rx_offload_del:
        if (cdev->is_peripheral)
                can_rx_offload_del(&cdev->offload);
out_reset_control_assert:
        reset_control_assert(cdev->rst);
clk_disable:
        m_can_clk_stop(cdev);

        return ret;
}
EXPORT_SYMBOL_GPL(m_can_class_register);

void m_can_class_unregister(struct m_can_classdev *cdev)
{
        unregister_candev(cdev->net);
        if (cdev->is_peripheral)
                can_rx_offload_del(&cdev->offload);
}
EXPORT_SYMBOL_GPL(m_can_class_unregister);

int m_can_class_suspend(struct device *dev)
{
        struct m_can_classdev *cdev = dev_get_drvdata(dev);
        struct net_device *ndev = cdev->net;
        int ret = 0;

        if (netif_running(ndev)) {
                netif_stop_queue(ndev);
                netif_device_detach(ndev);

                /* leave the chip running with rx interrupt enabled if it is
                 * used as a wake-up source. Coalescing needs to be reset then,
                 * the timer is cancelled here, interrupts are done in resume.
                 */
                if (cdev->pm_wake_source) {
                        hrtimer_cancel(&cdev->hrtimer);
                        m_can_write(cdev, M_CAN_IE, IR_RF0N);

                        if (cdev->ops->deinit)
                                ret = cdev->ops->deinit(cdev);
                } else {
                        m_can_stop(ndev);
                }

                m_can_clk_stop(cdev);
                cdev->can.state = CAN_STATE_SLEEPING;
        }

        if (!m_can_class_wakeup_pinctrl_enabled(cdev))
                pinctrl_pm_select_sleep_state(dev);

        return ret;
}
EXPORT_SYMBOL_GPL(m_can_class_suspend);

int m_can_class_resume(struct device *dev)
{
        struct m_can_classdev *cdev = dev_get_drvdata(dev);
        struct net_device *ndev = cdev->net;
        int ret = 0;

        if (!m_can_class_wakeup_pinctrl_enabled(cdev))
                pinctrl_pm_select_default_state(dev);

        if (netif_running(ndev)) {
                ret = m_can_clk_start(cdev);
                if (ret)
                        return ret;

                if (cdev->pm_wake_source) {
                        /* Restore active interrupts but disable coalescing as
                         * we may have missed important waterlevel interrupts
                         * between suspend and resume. Timers are already
                         * stopped in suspend. Here we enable all interrupts
                         * again.
                         */
                        cdev->active_interrupts |= IR_RF0N | IR_TEFN;

                        if (cdev->ops->init)
                                ret = cdev->ops->init(cdev);

                        cdev->can.state = m_can_state_get_by_psr(cdev);

                        m_can_write(cdev, M_CAN_IE, cdev->active_interrupts);
                } else {
                        ret  = m_can_start(ndev);
                        if (ret) {
                                m_can_clk_stop(cdev);
                                return ret;
                        }
                }

                netif_device_attach(ndev);
                netif_start_queue(ndev);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(m_can_class_resume);

MODULE_AUTHOR("Dong Aisheng <aisheng.dong@nxp.com>");
MODULE_AUTHOR("Dan Murphy <dmurphy@ti.com>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("CAN bus driver for Bosch M_CAN controller");