// SPDX-License-Identifier: GPL-2.0-only
/* CAN bus driver for Holt HI3110 CAN Controller with SPI Interface
 *
 * Copyright(C) Timesys Corporation 2016
 *
 * Based on Microchip 251x CAN Controller (mcp251x) Linux kernel driver
 * Copyright 2009 Christian Pellegrin EVOL S.r.l.
 * Copyright 2007 Raymarine UK, Ltd. All Rights Reserved.
 * Copyright 2006 Arcom Control Systems Ltd.
 *
 * Based on CAN bus driver for the CCAN controller written by
 * - Sascha Hauer, Marc Kleine-Budde, Pengutronix
 * - Simon Kallweit, intefo AG
 * Copyright 2007
 */

#include <linux/can/core.h>
#include <linux/can/dev.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/ethtool.h>
#include <linux/freezer.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/uaccess.h>

#define HI3110_MASTER_RESET 0x56
#define HI3110_READ_CTRL0 0xD2
#define HI3110_READ_CTRL1 0xD4
#define HI3110_READ_STATF 0xE2
#define HI3110_WRITE_CTRL0 0x14
#define HI3110_WRITE_CTRL1 0x16
#define HI3110_WRITE_INTE 0x1C
#define HI3110_WRITE_BTR0 0x18
#define HI3110_WRITE_BTR1 0x1A
#define HI3110_READ_BTR0 0xD6
#define HI3110_READ_BTR1 0xD8
#define HI3110_READ_INTF 0xDE
#define HI3110_READ_ERR 0xDC
#define HI3110_READ_FIFO_WOTIME 0x48
#define HI3110_WRITE_FIFO 0x12
#define HI3110_READ_MESSTAT 0xDA
#define HI3110_READ_REC 0xEA
#define HI3110_READ_TEC 0xEC

#define HI3110_CTRL0_MODE_MASK (7 << 5)
#define HI3110_CTRL0_NORMAL_MODE (0 << 5)
#define HI3110_CTRL0_LOOPBACK_MODE (1 << 5)
#define HI3110_CTRL0_MONITOR_MODE (2 << 5)
#define HI3110_CTRL0_SLEEP_MODE (3 << 5)
#define HI3110_CTRL0_INIT_MODE (4 << 5)

#define HI3110_CTRL1_TXEN BIT(7)

#define HI3110_INT_RXTMP BIT(7)
#define HI3110_INT_RXFIFO BIT(6)
#define HI3110_INT_TXCPLT BIT(5)
#define HI3110_INT_BUSERR BIT(4)
#define HI3110_INT_MCHG BIT(3)
#define HI3110_INT_WAKEUP BIT(2)
#define HI3110_INT_F1MESS BIT(1)
#define HI3110_INT_F0MESS BIT(0)

#define HI3110_ERR_BUSOFF BIT(7)
#define HI3110_ERR_TXERRP BIT(6)
#define HI3110_ERR_RXERRP BIT(5)
#define HI3110_ERR_BITERR BIT(4)
#define HI3110_ERR_FRMERR BIT(3)
#define HI3110_ERR_CRCERR BIT(2)
#define HI3110_ERR_ACKERR BIT(1)
#define HI3110_ERR_STUFERR BIT(0)
#define HI3110_ERR_PROTOCOL_MASK (0x1F)
#define HI3110_ERR_PASSIVE_MASK (0x60)

#define HI3110_STAT_RXFMTY BIT(1)
#define HI3110_STAT_BUSOFF BIT(2)
#define HI3110_STAT_ERRP BIT(3)
#define HI3110_STAT_ERRW BIT(4)
#define HI3110_STAT_TXMTY BIT(7)

#define HI3110_BTR0_SJW_SHIFT 6
#define HI3110_BTR0_BRP_SHIFT 0

#define HI3110_BTR1_SAMP_3PERBIT (1 << 7)
#define HI3110_BTR1_SAMP_1PERBIT (0 << 7)
#define HI3110_BTR1_TSEG2_SHIFT 4
#define HI3110_BTR1_TSEG1_SHIFT 0

#define HI3110_FIFO_WOTIME_TAG_OFF 0
#define HI3110_FIFO_WOTIME_ID_OFF 1
#define HI3110_FIFO_WOTIME_DLC_OFF 5
#define HI3110_FIFO_WOTIME_DAT_OFF 6

#define HI3110_FIFO_WOTIME_TAG_IDE BIT(7)
#define HI3110_FIFO_WOTIME_ID_RTR BIT(0)

#define HI3110_FIFO_TAG_OFF 0
#define HI3110_FIFO_ID_OFF 1
#define HI3110_FIFO_STD_DLC_OFF 3
#define HI3110_FIFO_STD_DATA_OFF 4
#define HI3110_FIFO_EXT_DLC_OFF 5
#define HI3110_FIFO_EXT_DATA_OFF 6

#define HI3110_CAN_MAX_DATA_LEN 8
#define HI3110_RX_BUF_LEN 15
#define HI3110_TX_STD_BUF_LEN 12
#define HI3110_TX_EXT_BUF_LEN 14
#define HI3110_CAN_FRAME_MAX_BITS 128
#define HI3110_EFF_FLAGS 0x18 /* IDE + SRR */

#define HI3110_TX_ECHO_SKB_MAX 1

#define HI3110_OST_DELAY_MS (10)

#define DEVICE_NAME "hi3110"

static const struct can_bittiming_const hi3110_bittiming_const = {
        .name = DEVICE_NAME,
        .tseg1_min = 2,
        .tseg1_max = 16,
        .tseg2_min = 2,
        .tseg2_max = 8,
        .sjw_max = 4,
        .brp_min = 1,
        .brp_max = 64,
        .brp_inc = 1,
};

enum hi3110_model {
        CAN_HI3110_HI3110 = 0x3110,
};

struct hi3110_priv {
        struct can_priv can;
        struct net_device *net;
        struct spi_device *spi;
        enum hi3110_model model;

        struct mutex hi3110_lock; /* SPI device lock */

        u8 *spi_tx_buf;
        u8 *spi_rx_buf;

        struct sk_buff *tx_skb;

        struct workqueue_struct *wq;
        struct work_struct tx_work;
        struct work_struct restart_work;

        int force_quit;
        int after_suspend;
#define HI3110_AFTER_SUSPEND_UP 1
#define HI3110_AFTER_SUSPEND_DOWN 2
#define HI3110_AFTER_SUSPEND_POWER 4
#define HI3110_AFTER_SUSPEND_RESTART 8
        int restart_tx;
        bool tx_busy;

        struct regulator *power;
        struct regulator *transceiver;
        struct clk *clk;
};

static void hi3110_clean(struct net_device *net)
{
        struct hi3110_priv *priv = netdev_priv(net);

        if (priv->tx_skb || priv->tx_busy)
                net->stats.tx_errors++;
        dev_kfree_skb(priv->tx_skb);
        if (priv->tx_busy)
                can_free_echo_skb(priv->net, 0, NULL);
        priv->tx_skb = NULL;
        priv->tx_busy = false;
}

/* Note about handling of error return of hi3110_spi_trans: accessing
 * registers via SPI is not really different conceptually than using
 * normal I/O assembler instructions, although it's much more
 * complicated from a practical POV. So it's not advisable to always
 * check the return value of this function. Imagine that every
 * read{b,l}, write{b,l} and friends would be bracketed in "if ( < 0)
 * error();", it would be a great mess (well there are some situation
 * when exception handling C++ like could be useful after all). So we
 * just check that transfers are OK at the beginning of our
 * conversation with the chip and to avoid doing really nasty things
 * (like injecting bogus packets in the network stack).
 */
static int hi3110_spi_trans(struct spi_device *spi, int len)
{
        struct hi3110_priv *priv = spi_get_drvdata(spi);
        struct spi_transfer t = {
                .tx_buf = priv->spi_tx_buf,
                .rx_buf = priv->spi_rx_buf,
                .len = len,
                .cs_change = 0,
        };
        struct spi_message m;
        int ret;

        spi_message_init(&m);
        spi_message_add_tail(&t, &m);

        ret = spi_sync(spi, &m);

        if (ret)
                dev_err(&spi->dev, "spi transfer failed: ret = %d\n", ret);
        return ret;
}

static int hi3110_cmd(struct spi_device *spi, u8 command)
{
        struct hi3110_priv *priv = spi_get_drvdata(spi);

        priv->spi_tx_buf[0] = command;
        dev_dbg(&spi->dev, "hi3110_cmd: %02X\n", command);

        return hi3110_spi_trans(spi, 1);
}

static u8 hi3110_read(struct spi_device *spi, u8 command)
{
        struct hi3110_priv *priv = spi_get_drvdata(spi);
        u8 val = 0;

        priv->spi_tx_buf[0] = command;
        hi3110_spi_trans(spi, 2);
        val = priv->spi_rx_buf[1];

        return val;
}

static void hi3110_write(struct spi_device *spi, u8 reg, u8 val)
{
        struct hi3110_priv *priv = spi_get_drvdata(spi);

        priv->spi_tx_buf[0] = reg;
        priv->spi_tx_buf[1] = val;
        hi3110_spi_trans(spi, 2);
}

static void hi3110_hw_tx_frame(struct spi_device *spi, u8 *buf, int len)
{
        struct hi3110_priv *priv = spi_get_drvdata(spi);

        priv->spi_tx_buf[0] = HI3110_WRITE_FIFO;
        memcpy(priv->spi_tx_buf + 1, buf, len);
        hi3110_spi_trans(spi, len + 1);
}

static void hi3110_hw_tx(struct spi_device *spi, struct can_frame *frame)
{
        u8 buf[HI3110_TX_EXT_BUF_LEN];

        buf[HI3110_FIFO_TAG_OFF] = 0;

        if (frame->can_id & CAN_EFF_FLAG) {
                /* Extended frame */
                buf[HI3110_FIFO_ID_OFF] = (frame->can_id & CAN_EFF_MASK) >> 21;
                buf[HI3110_FIFO_ID_OFF + 1] =
                        (((frame->can_id & CAN_EFF_MASK) >> 13) & 0xe0) |
                        HI3110_EFF_FLAGS |
                        (((frame->can_id & CAN_EFF_MASK) >> 15) & 0x07);
                buf[HI3110_FIFO_ID_OFF + 2] =
                        (frame->can_id & CAN_EFF_MASK) >> 7;
                buf[HI3110_FIFO_ID_OFF + 3] =
                        ((frame->can_id & CAN_EFF_MASK) << 1) |
                        ((frame->can_id & CAN_RTR_FLAG) ? 1 : 0);

                buf[HI3110_FIFO_EXT_DLC_OFF] = frame->len;

                memcpy(buf + HI3110_FIFO_EXT_DATA_OFF,
                       frame->data, frame->len);

                hi3110_hw_tx_frame(spi, buf, HI3110_TX_EXT_BUF_LEN -
                                   (HI3110_CAN_MAX_DATA_LEN - frame->len));
        } else {
                /* Standard frame */
                buf[HI3110_FIFO_ID_OFF] =   (frame->can_id & CAN_SFF_MASK) >> 3;
                buf[HI3110_FIFO_ID_OFF + 1] =
                        ((frame->can_id & CAN_SFF_MASK) << 5) |
                        ((frame->can_id & CAN_RTR_FLAG) ? (1 << 4) : 0);

                buf[HI3110_FIFO_STD_DLC_OFF] = frame->len;

                memcpy(buf + HI3110_FIFO_STD_DATA_OFF,
                       frame->data, frame->len);

                hi3110_hw_tx_frame(spi, buf, HI3110_TX_STD_BUF_LEN -
                                   (HI3110_CAN_MAX_DATA_LEN - frame->len));
        }
}

static void hi3110_hw_rx_frame(struct spi_device *spi, u8 *buf)
{
        struct hi3110_priv *priv = spi_get_drvdata(spi);

        priv->spi_tx_buf[0] = HI3110_READ_FIFO_WOTIME;
        hi3110_spi_trans(spi, HI3110_RX_BUF_LEN);
        memcpy(buf, priv->spi_rx_buf + 1, HI3110_RX_BUF_LEN - 1);
}

static void hi3110_hw_rx(struct spi_device *spi)
{
        struct hi3110_priv *priv = spi_get_drvdata(spi);
        struct sk_buff *skb;
        struct can_frame *frame;
        u8 buf[HI3110_RX_BUF_LEN - 1];

        skb = alloc_can_skb(priv->net, &frame);
        if (!skb) {
                priv->net->stats.rx_dropped++;
                return;
        }

        hi3110_hw_rx_frame(spi, buf);
        if (buf[HI3110_FIFO_WOTIME_TAG_OFF] & HI3110_FIFO_WOTIME_TAG_IDE) {
                /* IDE is recessive (1), indicating extended 29-bit frame */
                frame->can_id = CAN_EFF_FLAG;
                frame->can_id |=
                        (buf[HI3110_FIFO_WOTIME_ID_OFF] << 21) |
                        (((buf[HI3110_FIFO_WOTIME_ID_OFF + 1] & 0xE0) >> 5) << 18) |
                        ((buf[HI3110_FIFO_WOTIME_ID_OFF + 1] & 0x07) << 15) |
                        (buf[HI3110_FIFO_WOTIME_ID_OFF + 2] << 7) |
                        (buf[HI3110_FIFO_WOTIME_ID_OFF + 3] >> 1);
        } else {
                /* IDE is dominant (0), frame indicating standard 11-bit */
                frame->can_id =
                        (buf[HI3110_FIFO_WOTIME_ID_OFF] << 3) |
                        ((buf[HI3110_FIFO_WOTIME_ID_OFF + 1] & 0xE0) >> 5);
        }

        /* Data length */
        frame->len = can_cc_dlc2len(buf[HI3110_FIFO_WOTIME_DLC_OFF] & 0x0F);

        if (buf[HI3110_FIFO_WOTIME_ID_OFF + 3] & HI3110_FIFO_WOTIME_ID_RTR) {
                frame->can_id |= CAN_RTR_FLAG;
        } else {
                memcpy(frame->data, buf + HI3110_FIFO_WOTIME_DAT_OFF,
                       frame->len);

                priv->net->stats.rx_bytes += frame->len;
        }
        priv->net->stats.rx_packets++;

        netif_rx(skb);
}

static void hi3110_hw_sleep(struct spi_device *spi)
{
        hi3110_write(spi, HI3110_WRITE_CTRL0, HI3110_CTRL0_SLEEP_MODE);
}

static netdev_tx_t hi3110_hard_start_xmit(struct sk_buff *skb,
                                          struct net_device *net)
{
        struct hi3110_priv *priv = netdev_priv(net);
        struct spi_device *spi = priv->spi;

        if (priv->tx_skb || priv->tx_busy) {
                dev_err(&spi->dev, "hard_xmit called while tx busy\n");
                return NETDEV_TX_BUSY;
        }

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

        netif_stop_queue(net);
        priv->tx_skb = skb;
        queue_work(priv->wq, &priv->tx_work);

        return NETDEV_TX_OK;
}

static int hi3110_do_set_mode(struct net_device *net, enum can_mode mode)
{
        struct hi3110_priv *priv = netdev_priv(net);

        switch (mode) {
        case CAN_MODE_START:
                hi3110_clean(net);
                /* We have to delay work since SPI I/O may sleep */
                priv->can.state = CAN_STATE_ERROR_ACTIVE;
                priv->restart_tx = 1;
                if (priv->can.restart_ms == 0)
                        priv->after_suspend = HI3110_AFTER_SUSPEND_RESTART;
                queue_work(priv->wq, &priv->restart_work);
                break;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int hi3110_get_berr_counter(const struct net_device *net,
                                   struct can_berr_counter *bec)
{
        struct hi3110_priv *priv = netdev_priv(net);
        struct spi_device *spi = priv->spi;

        mutex_lock(&priv->hi3110_lock);
        bec->txerr = hi3110_read(spi, HI3110_READ_TEC);
        bec->rxerr = hi3110_read(spi, HI3110_READ_REC);
        mutex_unlock(&priv->hi3110_lock);

        return 0;
}

static int hi3110_set_normal_mode(struct spi_device *spi)
{
        struct hi3110_priv *priv = spi_get_drvdata(spi);
        u8 reg = 0;

        hi3110_write(spi, HI3110_WRITE_INTE, HI3110_INT_BUSERR |
                     HI3110_INT_RXFIFO | HI3110_INT_TXCPLT);

        /* Enable TX */
        hi3110_write(spi, HI3110_WRITE_CTRL1, HI3110_CTRL1_TXEN);

        if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
                reg = HI3110_CTRL0_LOOPBACK_MODE;
        else if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
                reg = HI3110_CTRL0_MONITOR_MODE;
        else
                reg = HI3110_CTRL0_NORMAL_MODE;

        hi3110_write(spi, HI3110_WRITE_CTRL0, reg);

        /* Wait for the device to enter the mode */
        mdelay(HI3110_OST_DELAY_MS);
        reg = hi3110_read(spi, HI3110_READ_CTRL0);
        if ((reg & HI3110_CTRL0_MODE_MASK) != reg)
                return -EBUSY;

        priv->can.state = CAN_STATE_ERROR_ACTIVE;
        return 0;
}

static int hi3110_do_set_bittiming(struct net_device *net)
{
        struct hi3110_priv *priv = netdev_priv(net);
        struct can_bittiming *bt = &priv->can.bittiming;
        struct spi_device *spi = priv->spi;

        hi3110_write(spi, HI3110_WRITE_BTR0,
                     ((bt->sjw - 1) << HI3110_BTR0_SJW_SHIFT) |
                     ((bt->brp - 1) << HI3110_BTR0_BRP_SHIFT));

        hi3110_write(spi, HI3110_WRITE_BTR1,
                     (priv->can.ctrlmode &
                      CAN_CTRLMODE_3_SAMPLES ?
                      HI3110_BTR1_SAMP_3PERBIT : HI3110_BTR1_SAMP_1PERBIT) |
                     ((bt->phase_seg1 + bt->prop_seg - 1)
                      << HI3110_BTR1_TSEG1_SHIFT) |
                     ((bt->phase_seg2 - 1) << HI3110_BTR1_TSEG2_SHIFT));

        dev_dbg(&spi->dev, "BT: 0x%02x 0x%02x\n",
                hi3110_read(spi, HI3110_READ_BTR0),
                hi3110_read(spi, HI3110_READ_BTR1));

        return 0;
}

static int hi3110_setup(struct net_device *net)
{
        hi3110_do_set_bittiming(net);
        return 0;
}

static int hi3110_hw_reset(struct spi_device *spi)
{
        u8 reg;
        int ret;

        /* Wait for oscillator startup timer after power up */
        mdelay(HI3110_OST_DELAY_MS);

        ret = hi3110_cmd(spi, HI3110_MASTER_RESET);
        if (ret)
                return ret;

        /* Wait for oscillator startup timer after reset */
        mdelay(HI3110_OST_DELAY_MS);

        reg = hi3110_read(spi, HI3110_READ_CTRL0);
        if ((reg & HI3110_CTRL0_MODE_MASK) != HI3110_CTRL0_INIT_MODE)
                return -ENODEV;

        /* As per the datasheet it appears the error flags are
         * not cleared on reset. Explicitly clear them by performing a read
         */
        hi3110_read(spi, HI3110_READ_ERR);

        return 0;
}

static int hi3110_hw_probe(struct spi_device *spi)
{
        u8 statf;

        hi3110_hw_reset(spi);

        /* Confirm correct operation by checking against reset values
         * in datasheet
         */
        statf = hi3110_read(spi, HI3110_READ_STATF);

        dev_dbg(&spi->dev, "statf: %02X\n", statf);

        if (statf != 0x82)
                return -ENODEV;

        return 0;
}

static int hi3110_power_enable(struct regulator *reg, int enable)
{
        if (IS_ERR_OR_NULL(reg))
                return 0;

        if (enable)
                return regulator_enable(reg);
        else
                return regulator_disable(reg);
}

static int hi3110_stop(struct net_device *net)
{
        struct hi3110_priv *priv = netdev_priv(net);
        struct spi_device *spi = priv->spi;

        close_candev(net);

        priv->force_quit = 1;
        free_irq(spi->irq, priv);

        mutex_lock(&priv->hi3110_lock);

        /* Disable transmit, interrupts and clear flags */
        hi3110_write(spi, HI3110_WRITE_CTRL1, 0x0);
        hi3110_write(spi, HI3110_WRITE_INTE, 0x0);
        hi3110_read(spi, HI3110_READ_INTF);

        hi3110_clean(net);

        hi3110_hw_sleep(spi);

        hi3110_power_enable(priv->transceiver, 0);

        priv->can.state = CAN_STATE_STOPPED;

        mutex_unlock(&priv->hi3110_lock);

        return 0;
}

static void hi3110_tx_work_handler(struct work_struct *ws)
{
        struct hi3110_priv *priv = container_of(ws, struct hi3110_priv,
                                                tx_work);
        struct spi_device *spi = priv->spi;
        struct net_device *net = priv->net;
        struct can_frame *frame;

        mutex_lock(&priv->hi3110_lock);
        if (priv->tx_skb) {
                if (priv->can.state == CAN_STATE_BUS_OFF) {
                        hi3110_clean(net);
                } else {
                        frame = (struct can_frame *)priv->tx_skb->data;
                        hi3110_hw_tx(spi, frame);
                        priv->tx_busy = true;
                        can_put_echo_skb(priv->tx_skb, net, 0, 0);
                        priv->tx_skb = NULL;
                }
        }
        mutex_unlock(&priv->hi3110_lock);
}

static void hi3110_restart_work_handler(struct work_struct *ws)
{
        struct hi3110_priv *priv = container_of(ws, struct hi3110_priv,
                                                restart_work);
        struct spi_device *spi = priv->spi;
        struct net_device *net = priv->net;

        mutex_lock(&priv->hi3110_lock);
        if (priv->after_suspend) {
                hi3110_hw_reset(spi);
                hi3110_setup(net);
                if (priv->after_suspend & HI3110_AFTER_SUSPEND_RESTART) {
                        hi3110_set_normal_mode(spi);
                } else if (priv->after_suspend & HI3110_AFTER_SUSPEND_UP) {
                        netif_device_attach(net);
                        hi3110_clean(net);
                        hi3110_set_normal_mode(spi);
                        netif_wake_queue(net);
                } else {
                        hi3110_hw_sleep(spi);
                }
                priv->after_suspend = 0;
                priv->force_quit = 0;
        }

        if (priv->restart_tx) {
                priv->restart_tx = 0;
                hi3110_hw_reset(spi);
                hi3110_setup(net);
                hi3110_clean(net);
                hi3110_set_normal_mode(spi);
                netif_wake_queue(net);
        }
        mutex_unlock(&priv->hi3110_lock);
}

static irqreturn_t hi3110_can_ist(int irq, void *dev_id)
{
        struct hi3110_priv *priv = dev_id;
        struct spi_device *spi = priv->spi;
        struct net_device *net = priv->net;

        mutex_lock(&priv->hi3110_lock);

        while (!priv->force_quit) {
                enum can_state new_state;
                u8 intf, eflag, statf;

                while (!(HI3110_STAT_RXFMTY &
                         (statf = hi3110_read(spi, HI3110_READ_STATF)))) {
                        hi3110_hw_rx(spi);
                }

                intf = hi3110_read(spi, HI3110_READ_INTF);
                eflag = hi3110_read(spi, HI3110_READ_ERR);
                /* Update can state */
                if (eflag & HI3110_ERR_BUSOFF)
                        new_state = CAN_STATE_BUS_OFF;
                else if (eflag & HI3110_ERR_PASSIVE_MASK)
                        new_state = CAN_STATE_ERROR_PASSIVE;
                else if (statf & HI3110_STAT_ERRW)
                        new_state = CAN_STATE_ERROR_WARNING;
                else
                        new_state = CAN_STATE_ERROR_ACTIVE;

                if (new_state != priv->can.state) {
                        struct can_frame *cf;
                        struct sk_buff *skb;
                        enum can_state rx_state, tx_state;
                        u8 rxerr, txerr;

                        skb = alloc_can_err_skb(net, &cf);

                        txerr = hi3110_read(spi, HI3110_READ_TEC);
                        rxerr = hi3110_read(spi, HI3110_READ_REC);
                        tx_state = txerr >= rxerr ? new_state : 0;
                        rx_state = txerr <= rxerr ? new_state : 0;
                        can_change_state(net, cf, tx_state, rx_state);

                        if (new_state == CAN_STATE_BUS_OFF) {
                                if (skb)
                                        netif_rx(skb);
                                can_bus_off(net);
                                if (priv->can.restart_ms == 0) {
                                        priv->force_quit = 1;
                                        hi3110_hw_sleep(spi);
                                        break;
                                }
                        } else if (skb) {
                                cf->can_id |= CAN_ERR_CNT;
                                cf->data[6] = txerr;
                                cf->data[7] = rxerr;
                                netif_rx(skb);
                        }
                }

                /* Update bus errors */
                if ((intf & HI3110_INT_BUSERR) &&
                    (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)) {
                        struct can_frame *cf;
                        struct sk_buff *skb;

                        /* Check for protocol errors */
                        if (eflag & HI3110_ERR_PROTOCOL_MASK) {
                                skb = alloc_can_err_skb(net, &cf);
                                if (skb)
                                        cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;

                                priv->can.can_stats.bus_error++;
                                if (eflag & HI3110_ERR_BITERR) {
                                        priv->net->stats.tx_errors++;
                                        if (skb)
                                                cf->data[2] |= CAN_ERR_PROT_BIT;
                                } else if (eflag & HI3110_ERR_FRMERR) {
                                        priv->net->stats.rx_errors++;
                                        if (skb)
                                                cf->data[2] |= CAN_ERR_PROT_FORM;
                                } else if (eflag & HI3110_ERR_STUFERR) {
                                        priv->net->stats.rx_errors++;
                                        if (skb)
                                                cf->data[2] |= CAN_ERR_PROT_STUFF;
                                } else if (eflag & HI3110_ERR_CRCERR) {
                                        priv->net->stats.rx_errors++;
                                        if (skb)
                                                cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
                                } else if (eflag & HI3110_ERR_ACKERR) {
                                        priv->net->stats.tx_errors++;
                                        if (skb)
                                                cf->data[3] |= CAN_ERR_PROT_LOC_ACK;
                                }

                                netdev_dbg(priv->net, "Bus Error\n");
                                if (skb) {
                                        cf->data[6] = hi3110_read(spi, HI3110_READ_TEC);
                                        cf->data[7] = hi3110_read(spi, HI3110_READ_REC);
                                        netif_rx(skb);
                                }
                        }
                }

                if (priv->tx_busy && statf & HI3110_STAT_TXMTY) {
                        net->stats.tx_packets++;
                        net->stats.tx_bytes += can_get_echo_skb(net, 0, NULL);
                        priv->tx_busy = false;
                        netif_wake_queue(net);
                }

                if (intf == 0)
                        break;
        }
        mutex_unlock(&priv->hi3110_lock);
        return IRQ_HANDLED;
}

static int hi3110_open(struct net_device *net)
{
        struct hi3110_priv *priv = netdev_priv(net);
        struct spi_device *spi = priv->spi;
        unsigned long flags = IRQF_ONESHOT | IRQF_TRIGGER_HIGH;
        int ret;

        ret = open_candev(net);
        if (ret)
                return ret;

        mutex_lock(&priv->hi3110_lock);
        ret = hi3110_power_enable(priv->transceiver, 1);
        if (ret)
                goto out_close_candev;

        priv->force_quit = 0;
        priv->tx_skb = NULL;
        priv->tx_busy = false;

        ret = request_threaded_irq(spi->irq, NULL, hi3110_can_ist,
                                   flags, DEVICE_NAME, priv);
        if (ret) {
                dev_err(&spi->dev, "failed to acquire irq %d\n", spi->irq);
                goto out_close;
        }

        ret = hi3110_hw_reset(spi);
        if (ret)
                goto out_free_irq;

        ret = hi3110_setup(net);
        if (ret)
                goto out_free_irq;

        ret = hi3110_set_normal_mode(spi);
        if (ret)
                goto out_free_irq;

        netif_wake_queue(net);
        mutex_unlock(&priv->hi3110_lock);

        return 0;

 out_free_irq:
        free_irq(spi->irq, priv);
        hi3110_hw_sleep(spi);
 out_close:
        hi3110_power_enable(priv->transceiver, 0);
 out_close_candev:
        close_candev(net);
        mutex_unlock(&priv->hi3110_lock);
        return ret;
}

static const struct net_device_ops hi3110_netdev_ops = {
        .ndo_open = hi3110_open,
        .ndo_stop = hi3110_stop,
        .ndo_start_xmit = hi3110_hard_start_xmit,
};

static const struct ethtool_ops hi3110_ethtool_ops = {
        .get_ts_info = ethtool_op_get_ts_info,
};

static const struct of_device_id hi3110_of_match[] = {
        {
                .compatible     = "holt,hi3110",
                .data           = (void *)CAN_HI3110_HI3110,
        },
        { }
};
MODULE_DEVICE_TABLE(of, hi3110_of_match);

static const struct spi_device_id hi3110_id_table[] = {
        {
                .name           = "hi3110",
                .driver_data    = (kernel_ulong_t)CAN_HI3110_HI3110,
        },
        { }
};
MODULE_DEVICE_TABLE(spi, hi3110_id_table);

static int hi3110_can_probe(struct spi_device *spi)
{
        struct device *dev = &spi->dev;
        struct net_device *net;
        struct hi3110_priv *priv;
        struct clk *clk;
        u32 freq;
        int ret;

        clk = devm_clk_get_optional(&spi->dev, NULL);
        if (IS_ERR(clk))
                return dev_err_probe(dev, PTR_ERR(clk), "no CAN clock source defined\n");

        if (clk) {
                freq = clk_get_rate(clk);
        } else {
                ret = device_property_read_u32(dev, "clock-frequency", &freq);
                if (ret)
                        return dev_err_probe(dev, ret, "Failed to get clock-frequency!\n");
        }

        /* Sanity check */
        if (freq > 40000000)
                return -ERANGE;

        /* Allocate can/net device */
        net = alloc_candev(sizeof(struct hi3110_priv), HI3110_TX_ECHO_SKB_MAX);
        if (!net)
                return -ENOMEM;

        ret = clk_prepare_enable(clk);
        if (ret)
                goto out_free;

        net->netdev_ops = &hi3110_netdev_ops;
        net->ethtool_ops = &hi3110_ethtool_ops;
        net->flags |= IFF_ECHO;

        priv = netdev_priv(net);
        priv->can.bittiming_const = &hi3110_bittiming_const;
        priv->can.do_set_mode = hi3110_do_set_mode;
        priv->can.do_get_berr_counter = hi3110_get_berr_counter;
        priv->can.clock.freq = freq / 2;
        priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES |
                CAN_CTRLMODE_LOOPBACK |
                CAN_CTRLMODE_LISTENONLY |
                CAN_CTRLMODE_BERR_REPORTING;

        priv->model = (enum hi3110_model)(uintptr_t)spi_get_device_match_data(spi);
        priv->net = net;
        priv->clk = clk;

        spi_set_drvdata(spi, priv);

        /* Configure the SPI bus */
        spi->bits_per_word = 8;
        ret = spi_setup(spi);
        if (ret)
                goto out_clk;

        priv->power = devm_regulator_get_optional(&spi->dev, "vdd");
        priv->transceiver = devm_regulator_get_optional(&spi->dev, "xceiver");
        if ((PTR_ERR(priv->power) == -EPROBE_DEFER) ||
            (PTR_ERR(priv->transceiver) == -EPROBE_DEFER)) {
                ret = -EPROBE_DEFER;
                goto out_clk;
        }

        ret = hi3110_power_enable(priv->power, 1);
        if (ret)
                goto out_clk;

        priv->wq = alloc_workqueue("hi3110_wq",
                                   WQ_FREEZABLE | WQ_MEM_RECLAIM | WQ_PERCPU,
                                   0);
        if (!priv->wq) {
                ret = -ENOMEM;
                goto out_clk;
        }
        INIT_WORK(&priv->tx_work, hi3110_tx_work_handler);
        INIT_WORK(&priv->restart_work, hi3110_restart_work_handler);

        priv->spi = spi;
        mutex_init(&priv->hi3110_lock);

        priv->spi_tx_buf = devm_kzalloc(&spi->dev, HI3110_RX_BUF_LEN,
                                        GFP_KERNEL);
        if (!priv->spi_tx_buf) {
                ret = -ENOMEM;
                goto error_probe;
        }
        priv->spi_rx_buf = devm_kzalloc(&spi->dev, HI3110_RX_BUF_LEN,
                                        GFP_KERNEL);

        if (!priv->spi_rx_buf) {
                ret = -ENOMEM;
                goto error_probe;
        }

        SET_NETDEV_DEV(net, &spi->dev);

        ret = hi3110_hw_probe(spi);
        if (ret) {
                dev_err_probe(dev, ret, "Cannot initialize %x. Wrong wiring?\n", priv->model);
                goto error_probe;
        }
        hi3110_hw_sleep(spi);

        ret = register_candev(net);
        if (ret)
                goto error_probe;

        netdev_info(net, "%x successfully initialized.\n", priv->model);

        return 0;

 error_probe:
        destroy_workqueue(priv->wq);
        priv->wq = NULL;
        hi3110_power_enable(priv->power, 0);

 out_clk:
        clk_disable_unprepare(clk);

 out_free:
        free_candev(net);

        return dev_err_probe(dev, ret, "Probe failed\n");
}

static void hi3110_can_remove(struct spi_device *spi)
{
        struct hi3110_priv *priv = spi_get_drvdata(spi);
        struct net_device *net = priv->net;

        unregister_candev(net);

        hi3110_power_enable(priv->power, 0);

        destroy_workqueue(priv->wq);
        priv->wq = NULL;

        clk_disable_unprepare(priv->clk);

        free_candev(net);
}

static int __maybe_unused hi3110_can_suspend(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct hi3110_priv *priv = spi_get_drvdata(spi);
        struct net_device *net = priv->net;

        priv->force_quit = 1;
        disable_irq(spi->irq);

        /* Note: at this point neither IST nor workqueues are running.
         * open/stop cannot be called anyway so locking is not needed
         */
        if (netif_running(net)) {
                netif_device_detach(net);

                hi3110_hw_sleep(spi);
                hi3110_power_enable(priv->transceiver, 0);
                priv->after_suspend = HI3110_AFTER_SUSPEND_UP;
        } else {
                priv->after_suspend = HI3110_AFTER_SUSPEND_DOWN;
        }

        if (!IS_ERR_OR_NULL(priv->power)) {
                regulator_disable(priv->power);
                priv->after_suspend |= HI3110_AFTER_SUSPEND_POWER;
        }

        return 0;
}

static int __maybe_unused hi3110_can_resume(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct hi3110_priv *priv = spi_get_drvdata(spi);

        if (priv->after_suspend & HI3110_AFTER_SUSPEND_POWER)
                hi3110_power_enable(priv->power, 1);

        if (priv->after_suspend & HI3110_AFTER_SUSPEND_UP) {
                hi3110_power_enable(priv->transceiver, 1);
                queue_work(priv->wq, &priv->restart_work);
        } else {
                priv->after_suspend = 0;
        }

        priv->force_quit = 0;
        enable_irq(spi->irq);
        return 0;
}

static SIMPLE_DEV_PM_OPS(hi3110_can_pm_ops, hi3110_can_suspend, hi3110_can_resume);

static struct spi_driver hi3110_can_driver = {
        .driver = {
                .name = DEVICE_NAME,
                .of_match_table = hi3110_of_match,
                .pm = &hi3110_can_pm_ops,
        },
        .id_table = hi3110_id_table,
        .probe = hi3110_can_probe,
        .remove = hi3110_can_remove,
};

module_spi_driver(hi3110_can_driver);

MODULE_AUTHOR("Akshay Bhat <akshay.bhat@timesys.com>");
MODULE_AUTHOR("Casey Fitzpatrick <casey.fitzpatrick@timesys.com>");
MODULE_DESCRIPTION("Holt HI-3110 CAN driver");
MODULE_LICENSE("GPL v2");