/*
 * Copyright (C) 1999 - 2010 Intel Corporation.
 * Copyright (C) 2010 LAPIS SEMICONDUCTOR CO., LTD.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/pci.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/error.h>

#define PCH_CTRL_INIT           BIT(0) /* The INIT bit of CANCONT register. */
#define PCH_CTRL_IE             BIT(1) /* The IE bit of CAN control register */
#define PCH_CTRL_IE_SIE_EIE     (BIT(3) | BIT(2) | BIT(1))
#define PCH_CTRL_CCE            BIT(6)
#define PCH_CTRL_OPT            BIT(7) /* The OPT bit of CANCONT register. */
#define PCH_OPT_SILENT          BIT(3) /* The Silent bit of CANOPT reg. */
#define PCH_OPT_LBACK           BIT(4) /* The LoopBack bit of CANOPT reg. */

#define PCH_CMASK_RX_TX_SET     0x00f3
#define PCH_CMASK_RX_TX_GET     0x0073
#define PCH_CMASK_ALL           0xff
#define PCH_CMASK_NEWDAT        BIT(2)
#define PCH_CMASK_CLRINTPND     BIT(3)
#define PCH_CMASK_CTRL          BIT(4)
#define PCH_CMASK_ARB           BIT(5)
#define PCH_CMASK_MASK          BIT(6)
#define PCH_CMASK_RDWR          BIT(7)
#define PCH_IF_MCONT_NEWDAT     BIT(15)
#define PCH_IF_MCONT_MSGLOST    BIT(14)
#define PCH_IF_MCONT_INTPND     BIT(13)
#define PCH_IF_MCONT_UMASK      BIT(12)
#define PCH_IF_MCONT_TXIE       BIT(11)
#define PCH_IF_MCONT_RXIE       BIT(10)
#define PCH_IF_MCONT_RMTEN      BIT(9)
#define PCH_IF_MCONT_TXRQXT     BIT(8)
#define PCH_IF_MCONT_EOB        BIT(7)
#define PCH_IF_MCONT_DLC        (BIT(0) | BIT(1) | BIT(2) | BIT(3))
#define PCH_MASK2_MDIR_MXTD     (BIT(14) | BIT(15))
#define PCH_ID2_DIR             BIT(13)
#define PCH_ID2_XTD             BIT(14)
#define PCH_ID_MSGVAL           BIT(15)
#define PCH_IF_CREQ_BUSY        BIT(15)

#define PCH_STATUS_INT          0x8000
#define PCH_RP                  0x00008000
#define PCH_REC                 0x00007f00
#define PCH_TEC                 0x000000ff

#define PCH_TX_OK               BIT(3)
#define PCH_RX_OK               BIT(4)
#define PCH_EPASSIV             BIT(5)
#define PCH_EWARN               BIT(6)
#define PCH_BUS_OFF             BIT(7)

/* bit position of certain controller bits. */
#define PCH_BIT_BRP_SHIFT       0
#define PCH_BIT_SJW_SHIFT       6
#define PCH_BIT_TSEG1_SHIFT     8
#define PCH_BIT_TSEG2_SHIFT     12
#define PCH_BIT_BRPE_BRPE_SHIFT 6

#define PCH_MSK_BITT_BRP        0x3f
#define PCH_MSK_BRPE_BRPE       0x3c0
#define PCH_MSK_CTRL_IE_SIE_EIE 0x07
#define PCH_COUNTER_LIMIT       10

#define PCH_CAN_CLK             50000000        /* 50MHz */

/*
 * Define the number of message object.
 * PCH CAN communications are done via Message RAM.
 * The Message RAM consists of 32 message objects.
 */
#define PCH_RX_OBJ_NUM          26
#define PCH_TX_OBJ_NUM          6
#define PCH_RX_OBJ_START        1
#define PCH_RX_OBJ_END          PCH_RX_OBJ_NUM
#define PCH_TX_OBJ_START        (PCH_RX_OBJ_END + 1)
#define PCH_TX_OBJ_END          (PCH_RX_OBJ_NUM + PCH_TX_OBJ_NUM)

#define PCH_FIFO_THRESH         16

/* TxRqst2 show status of MsgObjNo.17~32 */
#define PCH_TREQ2_TX_MASK       (((1 << PCH_TX_OBJ_NUM) - 1) <<\
                                                        (PCH_RX_OBJ_END - 16))

enum pch_ifreg {
        PCH_RX_IFREG,
        PCH_TX_IFREG,
};

enum pch_can_err {
        PCH_STUF_ERR = 1,
        PCH_FORM_ERR,
        PCH_ACK_ERR,
        PCH_BIT1_ERR,
        PCH_BIT0_ERR,
        PCH_CRC_ERR,
        PCH_LEC_ALL,
};

enum pch_can_mode {
        PCH_CAN_ENABLE,
        PCH_CAN_DISABLE,
        PCH_CAN_ALL,
        PCH_CAN_NONE,
        PCH_CAN_STOP,
        PCH_CAN_RUN,
};

struct pch_can_if_regs {
        u32 creq;
        u32 cmask;
        u32 mask1;
        u32 mask2;
        u32 id1;
        u32 id2;
        u32 mcont;
        u32 data[4];
        u32 rsv[13];
};

struct pch_can_regs {
        u32 cont;
        u32 stat;
        u32 errc;
        u32 bitt;
        u32 intr;
        u32 opt;
        u32 brpe;
        u32 reserve;
        struct pch_can_if_regs ifregs[2]; /* [0]=if1  [1]=if2 */
        u32 reserve1[8];
        u32 treq1;
        u32 treq2;
        u32 reserve2[6];
        u32 data1;
        u32 data2;
        u32 reserve3[6];
        u32 canipend1;
        u32 canipend2;
        u32 reserve4[6];
        u32 canmval1;
        u32 canmval2;
        u32 reserve5[37];
        u32 srst;
};

struct pch_can_priv {
        struct can_priv can;
        struct pci_dev *dev;
        u32 tx_enable[PCH_TX_OBJ_END];
        u32 rx_enable[PCH_TX_OBJ_END];
        u32 rx_link[PCH_TX_OBJ_END];
        u32 int_enables;
        struct net_device *ndev;
        struct pch_can_regs __iomem *regs;
        struct napi_struct napi;
        int tx_obj;     /* Point next Tx Obj index */
        int use_msi;
};

static const struct can_bittiming_const pch_can_bittiming_const = {
        .name = KBUILD_MODNAME,
        .tseg1_min = 2,
        .tseg1_max = 16,
        .tseg2_min = 1,
        .tseg2_max = 8,
        .sjw_max = 4,
        .brp_min = 1,
        .brp_max = 1024, /* 6bit + extended 4bit */
        .brp_inc = 1,
};

static const struct pci_device_id pch_pci_tbl[] = {
        {PCI_VENDOR_ID_INTEL, 0x8818, PCI_ANY_ID, PCI_ANY_ID,},
        {0,}
};
MODULE_DEVICE_TABLE(pci, pch_pci_tbl);

static inline void pch_can_bit_set(void __iomem *addr, u32 mask)
{
        iowrite32(ioread32(addr) | mask, addr);
}

static inline void pch_can_bit_clear(void __iomem *addr, u32 mask)
{
        iowrite32(ioread32(addr) & ~mask, addr);
}

static void pch_can_set_run_mode(struct pch_can_priv *priv,
                                 enum pch_can_mode mode)
{
        switch (mode) {
        case PCH_CAN_RUN:
                pch_can_bit_clear(&priv->regs->cont, PCH_CTRL_INIT);
                break;

        case PCH_CAN_STOP:
                pch_can_bit_set(&priv->regs->cont, PCH_CTRL_INIT);
                break;

        default:
                netdev_err(priv->ndev, "%s -> Invalid Mode.\n", __func__);
                break;
        }
}

static void pch_can_set_optmode(struct pch_can_priv *priv)
{
        u32 reg_val = ioread32(&priv->regs->opt);

        if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
                reg_val |= PCH_OPT_SILENT;

        if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
                reg_val |= PCH_OPT_LBACK;

        pch_can_bit_set(&priv->regs->cont, PCH_CTRL_OPT);
        iowrite32(reg_val, &priv->regs->opt);
}

static void pch_can_rw_msg_obj(void __iomem *creq_addr, u32 num)
{
        int counter = PCH_COUNTER_LIMIT;
        u32 ifx_creq;

        iowrite32(num, creq_addr);
        while (counter) {
                ifx_creq = ioread32(creq_addr) & PCH_IF_CREQ_BUSY;
                if (!ifx_creq)
                        break;
                counter--;
                udelay(1);
        }
        if (!counter)
                pr_err("%s:IF1 BUSY Flag is set forever.\n", __func__);
}

static void pch_can_set_int_enables(struct pch_can_priv *priv,
                                    enum pch_can_mode interrupt_no)
{
        switch (interrupt_no) {
        case PCH_CAN_DISABLE:
                pch_can_bit_clear(&priv->regs->cont, PCH_CTRL_IE);
                break;

        case PCH_CAN_ALL:
                pch_can_bit_set(&priv->regs->cont, PCH_CTRL_IE_SIE_EIE);
                break;

        case PCH_CAN_NONE:
                pch_can_bit_clear(&priv->regs->cont, PCH_CTRL_IE_SIE_EIE);
                break;

        default:
                netdev_err(priv->ndev, "Invalid interrupt number.\n");
                break;
        }
}

static void pch_can_set_rxtx(struct pch_can_priv *priv, u32 buff_num,
                             int set, enum pch_ifreg dir)
{
        u32 ie;

        if (dir)
                ie = PCH_IF_MCONT_TXIE;
        else
                ie = PCH_IF_MCONT_RXIE;

        /* Reading the Msg buffer from Message RAM to IF1/2 registers. */
        iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[dir].cmask);
        pch_can_rw_msg_obj(&priv->regs->ifregs[dir].creq, buff_num);

        /* Setting the IF1/2MASK1 register to access MsgVal and RxIE bits */
        iowrite32(PCH_CMASK_RDWR | PCH_CMASK_ARB | PCH_CMASK_CTRL,
                  &priv->regs->ifregs[dir].cmask);

        if (set) {
                /* Setting the MsgVal and RxIE/TxIE bits */
                pch_can_bit_set(&priv->regs->ifregs[dir].mcont, ie);
                pch_can_bit_set(&priv->regs->ifregs[dir].id2, PCH_ID_MSGVAL);
        } else {
                /* Clearing the MsgVal and RxIE/TxIE bits */
                pch_can_bit_clear(&priv->regs->ifregs[dir].mcont, ie);
                pch_can_bit_clear(&priv->regs->ifregs[dir].id2, PCH_ID_MSGVAL);
        }

        pch_can_rw_msg_obj(&priv->regs->ifregs[dir].creq, buff_num);
}

static void pch_can_set_rx_all(struct pch_can_priv *priv, int set)
{
        int i;

        /* Traversing to obtain the object configured as receivers. */
        for (i = PCH_RX_OBJ_START; i <= PCH_RX_OBJ_END; i++)
                pch_can_set_rxtx(priv, i, set, PCH_RX_IFREG);
}

static void pch_can_set_tx_all(struct pch_can_priv *priv, int set)
{
        int i;

        /* Traversing to obtain the object configured as transmit object. */
        for (i = PCH_TX_OBJ_START; i <= PCH_TX_OBJ_END; i++)
                pch_can_set_rxtx(priv, i, set, PCH_TX_IFREG);
}

static u32 pch_can_int_pending(struct pch_can_priv *priv)
{
        return ioread32(&priv->regs->intr) & 0xffff;
}

static void pch_can_clear_if_buffers(struct pch_can_priv *priv)
{
        int i; /* Msg Obj ID (1~32) */

        for (i = PCH_RX_OBJ_START; i <= PCH_TX_OBJ_END; i++) {
                iowrite32(PCH_CMASK_RX_TX_SET, &priv->regs->ifregs[0].cmask);
                iowrite32(0xffff, &priv->regs->ifregs[0].mask1);
                iowrite32(0xffff, &priv->regs->ifregs[0].mask2);
                iowrite32(0x0, &priv->regs->ifregs[0].id1);
                iowrite32(0x0, &priv->regs->ifregs[0].id2);
                iowrite32(0x0, &priv->regs->ifregs[0].mcont);
                iowrite32(0x0, &priv->regs->ifregs[0].data[0]);
                iowrite32(0x0, &priv->regs->ifregs[0].data[1]);
                iowrite32(0x0, &priv->regs->ifregs[0].data[2]);
                iowrite32(0x0, &priv->regs->ifregs[0].data[3]);
                iowrite32(PCH_CMASK_RDWR | PCH_CMASK_MASK |
                          PCH_CMASK_ARB | PCH_CMASK_CTRL,
                          &priv->regs->ifregs[0].cmask);
                pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, i);
        }
}

static void pch_can_config_rx_tx_buffers(struct pch_can_priv *priv)
{
        int i;

        for (i = PCH_RX_OBJ_START; i <= PCH_RX_OBJ_END; i++) {
                iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[0].cmask);
                pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, i);

                iowrite32(0x0, &priv->regs->ifregs[0].id1);
                iowrite32(0x0, &priv->regs->ifregs[0].id2);

                pch_can_bit_set(&priv->regs->ifregs[0].mcont,
                                PCH_IF_MCONT_UMASK);

                /* In case FIFO mode, Last EoB of Rx Obj must be 1 */
                if (i == PCH_RX_OBJ_END)
                        pch_can_bit_set(&priv->regs->ifregs[0].mcont,
                                        PCH_IF_MCONT_EOB);
                else
                        pch_can_bit_clear(&priv->regs->ifregs[0].mcont,
                                          PCH_IF_MCONT_EOB);

                iowrite32(0, &priv->regs->ifregs[0].mask1);
                pch_can_bit_clear(&priv->regs->ifregs[0].mask2,
                                  0x1fff | PCH_MASK2_MDIR_MXTD);

                /* Setting CMASK for writing */
                iowrite32(PCH_CMASK_RDWR | PCH_CMASK_MASK | PCH_CMASK_ARB |
                          PCH_CMASK_CTRL, &priv->regs->ifregs[0].cmask);

                pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, i);
        }

        for (i = PCH_TX_OBJ_START; i <= PCH_TX_OBJ_END; i++) {
                iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[1].cmask);
                pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, i);

                /* Resetting DIR bit for reception */
                iowrite32(0x0, &priv->regs->ifregs[1].id1);
                iowrite32(PCH_ID2_DIR, &priv->regs->ifregs[1].id2);

                /* Setting EOB bit for transmitter */
                iowrite32(PCH_IF_MCONT_EOB | PCH_IF_MCONT_UMASK,
                          &priv->regs->ifregs[1].mcont);

                iowrite32(0, &priv->regs->ifregs[1].mask1);
                pch_can_bit_clear(&priv->regs->ifregs[1].mask2, 0x1fff);

                /* Setting CMASK for writing */
                iowrite32(PCH_CMASK_RDWR | PCH_CMASK_MASK | PCH_CMASK_ARB |
                          PCH_CMASK_CTRL, &priv->regs->ifregs[1].cmask);

                pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, i);
        }
}

static void pch_can_init(struct pch_can_priv *priv)
{
        /* Stopping the Can device. */
        pch_can_set_run_mode(priv, PCH_CAN_STOP);

        /* Clearing all the message object buffers. */
        pch_can_clear_if_buffers(priv);

        /* Configuring the respective message object as either rx/tx object. */
        pch_can_config_rx_tx_buffers(priv);

        /* Enabling the interrupts. */
        pch_can_set_int_enables(priv, PCH_CAN_ALL);
}

static void pch_can_release(struct pch_can_priv *priv)
{
        /* Stooping the CAN device. */
        pch_can_set_run_mode(priv, PCH_CAN_STOP);

        /* Disabling the interrupts. */
        pch_can_set_int_enables(priv, PCH_CAN_NONE);

        /* Disabling all the receive object. */
        pch_can_set_rx_all(priv, 0);

        /* Disabling all the transmit object. */
        pch_can_set_tx_all(priv, 0);
}

/* This function clears interrupt(s) from the CAN device. */
static void pch_can_int_clr(struct pch_can_priv *priv, u32 mask)
{
        /* Clear interrupt for transmit object */
        if ((mask >= PCH_RX_OBJ_START) && (mask <= PCH_RX_OBJ_END)) {
                /* Setting CMASK for clearing the reception interrupts. */
                iowrite32(PCH_CMASK_RDWR | PCH_CMASK_CTRL | PCH_CMASK_ARB,
                          &priv->regs->ifregs[0].cmask);

                /* Clearing the Dir bit. */
                pch_can_bit_clear(&priv->regs->ifregs[0].id2, PCH_ID2_DIR);

                /* Clearing NewDat & IntPnd */
                pch_can_bit_clear(&priv->regs->ifregs[0].mcont,
                                  PCH_IF_MCONT_NEWDAT | PCH_IF_MCONT_INTPND);

                pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, mask);
        } else if ((mask >= PCH_TX_OBJ_START) && (mask <= PCH_TX_OBJ_END)) {
                /*
                 * Setting CMASK for clearing interrupts for frame transmission.
                 */
                iowrite32(PCH_CMASK_RDWR | PCH_CMASK_CTRL | PCH_CMASK_ARB,
                          &priv->regs->ifregs[1].cmask);

                /* Resetting the ID registers. */
                pch_can_bit_set(&priv->regs->ifregs[1].id2,
                               PCH_ID2_DIR | (0x7ff << 2));
                iowrite32(0x0, &priv->regs->ifregs[1].id1);

                /* Claring NewDat, TxRqst & IntPnd */
                pch_can_bit_clear(&priv->regs->ifregs[1].mcont,
                                  PCH_IF_MCONT_NEWDAT | PCH_IF_MCONT_INTPND |
                                  PCH_IF_MCONT_TXRQXT);
                pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, mask);
        }
}

static void pch_can_reset(struct pch_can_priv *priv)
{
        /* write to sw reset register */
        iowrite32(1, &priv->regs->srst);
        iowrite32(0, &priv->regs->srst);
}

static void pch_can_error(struct net_device *ndev, u32 status)
{
        struct sk_buff *skb;
        struct pch_can_priv *priv = netdev_priv(ndev);
        struct can_frame *cf;
        u32 errc, lec;
        struct net_device_stats *stats = &(priv->ndev->stats);
        enum can_state state = priv->can.state;

        skb = alloc_can_err_skb(ndev, &cf);
        if (!skb)
                return;

        if (status & PCH_BUS_OFF) {
                pch_can_set_tx_all(priv, 0);
                pch_can_set_rx_all(priv, 0);
                state = CAN_STATE_BUS_OFF;
                cf->can_id |= CAN_ERR_BUSOFF;
                priv->can.can_stats.bus_off++;
                can_bus_off(ndev);
        }

        errc = ioread32(&priv->regs->errc);
        /* Warning interrupt. */
        if (status & PCH_EWARN) {
                state = CAN_STATE_ERROR_WARNING;
                priv->can.can_stats.error_warning++;
                cf->can_id |= CAN_ERR_CRTL;
                if (((errc & PCH_REC) >> 8) > 96)
                        cf->data[1] |= CAN_ERR_CRTL_RX_WARNING;
                if ((errc & PCH_TEC) > 96)
                        cf->data[1] |= CAN_ERR_CRTL_TX_WARNING;
                netdev_dbg(ndev,
                        "%s -> Error Counter is more than 96.\n", __func__);
        }
        /* Error passive interrupt. */
        if (status & PCH_EPASSIV) {
                priv->can.can_stats.error_passive++;
                state = CAN_STATE_ERROR_PASSIVE;
                cf->can_id |= CAN_ERR_CRTL;
                if (errc & PCH_RP)
                        cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
                if ((errc & PCH_TEC) > 127)
                        cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE;
                netdev_dbg(ndev,
                        "%s -> CAN controller is ERROR PASSIVE .\n", __func__);
        }

        lec = status & PCH_LEC_ALL;
        switch (lec) {
        case PCH_STUF_ERR:
                cf->data[2] |= CAN_ERR_PROT_STUFF;
                priv->can.can_stats.bus_error++;
                stats->rx_errors++;
                break;
        case PCH_FORM_ERR:
                cf->data[2] |= CAN_ERR_PROT_FORM;
                priv->can.can_stats.bus_error++;
                stats->rx_errors++;
                break;
        case PCH_ACK_ERR:
                cf->can_id |= CAN_ERR_ACK;
                priv->can.can_stats.bus_error++;
                stats->rx_errors++;
                break;
        case PCH_BIT1_ERR:
        case PCH_BIT0_ERR:
                cf->data[2] |= CAN_ERR_PROT_BIT;
                priv->can.can_stats.bus_error++;
                stats->rx_errors++;
                break;
        case PCH_CRC_ERR:
                cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ;
                priv->can.can_stats.bus_error++;
                stats->rx_errors++;
                break;
        case PCH_LEC_ALL: /* Written by CPU. No error status */
                break;
        }

        cf->data[6] = errc & PCH_TEC;
        cf->data[7] = (errc & PCH_REC) >> 8;

        priv->can.state = state;
        netif_receive_skb(skb);

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

static irqreturn_t pch_can_interrupt(int irq, void *dev_id)
{
        struct net_device *ndev = (struct net_device *)dev_id;
        struct pch_can_priv *priv = netdev_priv(ndev);

        if (!pch_can_int_pending(priv))
                return IRQ_NONE;

        pch_can_set_int_enables(priv, PCH_CAN_NONE);
        napi_schedule(&priv->napi);
        return IRQ_HANDLED;
}

static void pch_fifo_thresh(struct pch_can_priv *priv, int obj_id)
{
        if (obj_id < PCH_FIFO_THRESH) {
                iowrite32(PCH_CMASK_RDWR | PCH_CMASK_CTRL |
                          PCH_CMASK_ARB, &priv->regs->ifregs[0].cmask);

                /* Clearing the Dir bit. */
                pch_can_bit_clear(&priv->regs->ifregs[0].id2, PCH_ID2_DIR);

                /* Clearing NewDat & IntPnd */
                pch_can_bit_clear(&priv->regs->ifregs[0].mcont,
                                  PCH_IF_MCONT_INTPND);
                pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, obj_id);
        } else if (obj_id > PCH_FIFO_THRESH) {
                pch_can_int_clr(priv, obj_id);
        } else if (obj_id == PCH_FIFO_THRESH) {
                int cnt;
                for (cnt = 0; cnt < PCH_FIFO_THRESH; cnt++)
                        pch_can_int_clr(priv, cnt + 1);
        }
}

static void pch_can_rx_msg_lost(struct net_device *ndev, int obj_id)
{
        struct pch_can_priv *priv = netdev_priv(ndev);
        struct net_device_stats *stats = &(priv->ndev->stats);
        struct sk_buff *skb;
        struct can_frame *cf;

        netdev_dbg(priv->ndev, "Msg Obj is overwritten.\n");
        pch_can_bit_clear(&priv->regs->ifregs[0].mcont,
                          PCH_IF_MCONT_MSGLOST);
        iowrite32(PCH_CMASK_RDWR | PCH_CMASK_CTRL,
                  &priv->regs->ifregs[0].cmask);
        pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, obj_id);

        skb = alloc_can_err_skb(ndev, &cf);
        if (!skb)
                return;

        cf->can_id |= CAN_ERR_CRTL;
        cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
        stats->rx_over_errors++;
        stats->rx_errors++;

        netif_receive_skb(skb);
}

static int pch_can_rx_normal(struct net_device *ndev, u32 obj_num, int quota)
{
        u32 reg;
        canid_t id;
        int rcv_pkts = 0;
        struct sk_buff *skb;
        struct can_frame *cf;
        struct pch_can_priv *priv = netdev_priv(ndev);
        struct net_device_stats *stats = &(priv->ndev->stats);
        int i;
        u32 id2;
        u16 data_reg;

        do {
                /* Reading the message object from the Message RAM */
                iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[0].cmask);
                pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, obj_num);

                /* Reading the MCONT register. */
                reg = ioread32(&priv->regs->ifregs[0].mcont);

                if (reg & PCH_IF_MCONT_EOB)
                        break;

                /* If MsgLost bit set. */
                if (reg & PCH_IF_MCONT_MSGLOST) {
                        pch_can_rx_msg_lost(ndev, obj_num);
                        rcv_pkts++;
                        quota--;
                        obj_num++;
                        continue;
                } else if (!(reg & PCH_IF_MCONT_NEWDAT)) {
                        obj_num++;
                        continue;
                }

                skb = alloc_can_skb(priv->ndev, &cf);
                if (!skb) {
                        netdev_err(ndev, "alloc_can_skb Failed\n");
                        return rcv_pkts;
                }

                /* Get Received data */
                id2 = ioread32(&priv->regs->ifregs[0].id2);
                if (id2 & PCH_ID2_XTD) {
                        id = (ioread32(&priv->regs->ifregs[0].id1) & 0xffff);
                        id |= (((id2) & 0x1fff) << 16);
                        cf->can_id = id | CAN_EFF_FLAG;
                } else {
                        id = (id2 >> 2) & CAN_SFF_MASK;
                        cf->can_id = id;
                }

                if (id2 & PCH_ID2_DIR)
                        cf->can_id |= CAN_RTR_FLAG;

                cf->can_dlc = get_can_dlc((ioread32(&priv->regs->
                                                    ifregs[0].mcont)) & 0xF);

                for (i = 0; i < cf->can_dlc; i += 2) {
                        data_reg = ioread16(&priv->regs->ifregs[0].data[i / 2]);
                        cf->data[i] = data_reg;
                        cf->data[i + 1] = data_reg >> 8;
                }

                netif_receive_skb(skb);
                rcv_pkts++;
                stats->rx_packets++;
                quota--;
                stats->rx_bytes += cf->can_dlc;

                pch_fifo_thresh(priv, obj_num);
                obj_num++;
        } while (quota > 0);

        return rcv_pkts;
}

static void pch_can_tx_complete(struct net_device *ndev, u32 int_stat)
{
        struct pch_can_priv *priv = netdev_priv(ndev);
        struct net_device_stats *stats = &(priv->ndev->stats);
        u32 dlc;

        can_get_echo_skb(ndev, int_stat - PCH_RX_OBJ_END - 1);
        iowrite32(PCH_CMASK_RX_TX_GET | PCH_CMASK_CLRINTPND,
                  &priv->regs->ifregs[1].cmask);
        pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, int_stat);
        dlc = get_can_dlc(ioread32(&priv->regs->ifregs[1].mcont) &
                          PCH_IF_MCONT_DLC);
        stats->tx_bytes += dlc;
        stats->tx_packets++;
        if (int_stat == PCH_TX_OBJ_END)
                netif_wake_queue(ndev);
}

static int pch_can_poll(struct napi_struct *napi, int quota)
{
        struct net_device *ndev = napi->dev;
        struct pch_can_priv *priv = netdev_priv(ndev);
        u32 int_stat;
        u32 reg_stat;
        int quota_save = quota;

        int_stat = pch_can_int_pending(priv);
        if (!int_stat)
                goto end;

        if (int_stat == PCH_STATUS_INT) {
                reg_stat = ioread32(&priv->regs->stat);

                if ((reg_stat & (PCH_BUS_OFF | PCH_LEC_ALL)) &&
                   ((reg_stat & PCH_LEC_ALL) != PCH_LEC_ALL)) {
                        pch_can_error(ndev, reg_stat);
                        quota--;
                }

                if (reg_stat & (PCH_TX_OK | PCH_RX_OK))
                        pch_can_bit_clear(&priv->regs->stat,
                                          reg_stat & (PCH_TX_OK | PCH_RX_OK));

                int_stat = pch_can_int_pending(priv);
        }

        if (quota == 0)
                goto end;

        if ((int_stat >= PCH_RX_OBJ_START) && (int_stat <= PCH_RX_OBJ_END)) {
                quota -= pch_can_rx_normal(ndev, int_stat, quota);
        } else if ((int_stat >= PCH_TX_OBJ_START) &&
                   (int_stat <= PCH_TX_OBJ_END)) {
                /* Handle transmission interrupt */
                pch_can_tx_complete(ndev, int_stat);
        }

end:
        napi_complete(napi);
        pch_can_set_int_enables(priv, PCH_CAN_ALL);

        return quota_save - quota;
}

static int pch_set_bittiming(struct net_device *ndev)
{
        struct pch_can_priv *priv = netdev_priv(ndev);
        const struct can_bittiming *bt = &priv->can.bittiming;
        u32 canbit;
        u32 bepe;

        /* Setting the CCE bit for accessing the Can Timing register. */
        pch_can_bit_set(&priv->regs->cont, PCH_CTRL_CCE);

        canbit = (bt->brp - 1) & PCH_MSK_BITT_BRP;
        canbit |= (bt->sjw - 1) << PCH_BIT_SJW_SHIFT;
        canbit |= (bt->phase_seg1 + bt->prop_seg - 1) << PCH_BIT_TSEG1_SHIFT;
        canbit |= (bt->phase_seg2 - 1) << PCH_BIT_TSEG2_SHIFT;
        bepe = ((bt->brp - 1) & PCH_MSK_BRPE_BRPE) >> PCH_BIT_BRPE_BRPE_SHIFT;
        iowrite32(canbit, &priv->regs->bitt);
        iowrite32(bepe, &priv->regs->brpe);
        pch_can_bit_clear(&priv->regs->cont, PCH_CTRL_CCE);

        return 0;
}

static void pch_can_start(struct net_device *ndev)
{
        struct pch_can_priv *priv = netdev_priv(ndev);

        if (priv->can.state != CAN_STATE_STOPPED)
                pch_can_reset(priv);

        pch_set_bittiming(ndev);
        pch_can_set_optmode(priv);

        pch_can_set_tx_all(priv, 1);
        pch_can_set_rx_all(priv, 1);

        /* Setting the CAN to run mode. */
        pch_can_set_run_mode(priv, PCH_CAN_RUN);

        priv->can.state = CAN_STATE_ERROR_ACTIVE;

        return;
}

static int pch_can_do_set_mode(struct net_device *ndev, enum can_mode mode)
{
        int ret = 0;

        switch (mode) {
        case CAN_MODE_START:
                pch_can_start(ndev);
                netif_wake_queue(ndev);
                break;
        default:
                ret = -EOPNOTSUPP;
                break;
        }

        return ret;
}

static int pch_can_open(struct net_device *ndev)
{
        struct pch_can_priv *priv = netdev_priv(ndev);
        int retval;

        /* Regstering the interrupt. */
        retval = request_irq(priv->dev->irq, pch_can_interrupt, IRQF_SHARED,
                             ndev->name, ndev);
        if (retval) {
                netdev_err(ndev, "request_irq failed.\n");
                goto req_irq_err;
        }

        /* Open common can device */
        retval = open_candev(ndev);
        if (retval) {
                netdev_err(ndev, "open_candev() failed %d\n", retval);
                goto err_open_candev;
        }

        pch_can_init(priv);
        pch_can_start(ndev);
        napi_enable(&priv->napi);
        netif_start_queue(ndev);

        return 0;

err_open_candev:
        free_irq(priv->dev->irq, ndev);
req_irq_err:
        pch_can_release(priv);

        return retval;
}

static int pch_close(struct net_device *ndev)
{
        struct pch_can_priv *priv = netdev_priv(ndev);

        netif_stop_queue(ndev);
        napi_disable(&priv->napi);
        pch_can_release(priv);
        free_irq(priv->dev->irq, ndev);
        close_candev(ndev);
        priv->can.state = CAN_STATE_STOPPED;
        return 0;
}

static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev)
{
        struct pch_can_priv *priv = netdev_priv(ndev);
        struct can_frame *cf = (struct can_frame *)skb->data;
        int tx_obj_no;
        int i;
        u32 id2;

        if (can_dropped_invalid_skb(ndev, skb))
                return NETDEV_TX_OK;

        tx_obj_no = priv->tx_obj;
        if (priv->tx_obj == PCH_TX_OBJ_END) {
                if (ioread32(&priv->regs->treq2) & PCH_TREQ2_TX_MASK)
                        netif_stop_queue(ndev);

                priv->tx_obj = PCH_TX_OBJ_START;
        } else {
                priv->tx_obj++;
        }

        /* Setting the CMASK register. */
        pch_can_bit_set(&priv->regs->ifregs[1].cmask, PCH_CMASK_ALL);

        /* If ID extended is set. */
        if (cf->can_id & CAN_EFF_FLAG) {
                iowrite32(cf->can_id & 0xffff, &priv->regs->ifregs[1].id1);
                id2 = ((cf->can_id >> 16) & 0x1fff) | PCH_ID2_XTD;
        } else {
                iowrite32(0, &priv->regs->ifregs[1].id1);
                id2 = (cf->can_id & CAN_SFF_MASK) << 2;
        }

        id2 |= PCH_ID_MSGVAL;

        /* If remote frame has to be transmitted.. */
        if (!(cf->can_id & CAN_RTR_FLAG))
                id2 |= PCH_ID2_DIR;

        iowrite32(id2, &priv->regs->ifregs[1].id2);

        /* Copy data to register */
        for (i = 0; i < cf->can_dlc; i += 2) {
                iowrite16(cf->data[i] | (cf->data[i + 1] << 8),
                          &priv->regs->ifregs[1].data[i / 2]);
        }

        can_put_echo_skb(skb, ndev, tx_obj_no - PCH_RX_OBJ_END - 1);

        /* Set the size of the data. Update if2_mcont */
        iowrite32(cf->can_dlc | PCH_IF_MCONT_NEWDAT | PCH_IF_MCONT_TXRQXT |
                  PCH_IF_MCONT_TXIE, &priv->regs->ifregs[1].mcont);

        pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, tx_obj_no);

        return NETDEV_TX_OK;
}

static const struct net_device_ops pch_can_netdev_ops = {
        .ndo_open               = pch_can_open,
        .ndo_stop               = pch_close,
        .ndo_start_xmit         = pch_xmit,
        .ndo_change_mtu         = can_change_mtu,
};

static void pch_can_remove(struct pci_dev *pdev)
{
        struct net_device *ndev = pci_get_drvdata(pdev);
        struct pch_can_priv *priv = netdev_priv(ndev);

        unregister_candev(priv->ndev);
        if (priv->use_msi)
                pci_disable_msi(priv->dev);
        pci_release_regions(pdev);
        pci_disable_device(pdev);
        pch_can_reset(priv);
        pci_iounmap(pdev, priv->regs);
        free_candev(priv->ndev);
}

#ifdef CONFIG_PM
static void pch_can_set_int_custom(struct pch_can_priv *priv)
{
        /* Clearing the IE, SIE and EIE bits of Can control register. */
        pch_can_bit_clear(&priv->regs->cont, PCH_CTRL_IE_SIE_EIE);

        /* Appropriately setting them. */
        pch_can_bit_set(&priv->regs->cont,
                        ((priv->int_enables & PCH_MSK_CTRL_IE_SIE_EIE) << 1));
}

/* This function retrieves interrupt enabled for the CAN device. */
static u32 pch_can_get_int_enables(struct pch_can_priv *priv)
{
        /* Obtaining the status of IE, SIE and EIE interrupt bits. */
        return (ioread32(&priv->regs->cont) & PCH_CTRL_IE_SIE_EIE) >> 1;
}

static u32 pch_can_get_rxtx_ir(struct pch_can_priv *priv, u32 buff_num,
                               enum pch_ifreg dir)
{
        u32 ie, enable;

        if (dir)
                ie = PCH_IF_MCONT_RXIE;
        else
                ie = PCH_IF_MCONT_TXIE;

        iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[dir].cmask);
        pch_can_rw_msg_obj(&priv->regs->ifregs[dir].creq, buff_num);

        if (((ioread32(&priv->regs->ifregs[dir].id2)) & PCH_ID_MSGVAL) &&
                        ((ioread32(&priv->regs->ifregs[dir].mcont)) & ie))
                enable = 1;
        else
                enable = 0;

        return enable;
}

static void pch_can_set_rx_buffer_link(struct pch_can_priv *priv,
                                       u32 buffer_num, int set)
{
        iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[0].cmask);
        pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, buffer_num);
        iowrite32(PCH_CMASK_RDWR | PCH_CMASK_CTRL,
                  &priv->regs->ifregs[0].cmask);
        if (set)
                pch_can_bit_clear(&priv->regs->ifregs[0].mcont,
                                  PCH_IF_MCONT_EOB);
        else
                pch_can_bit_set(&priv->regs->ifregs[0].mcont, PCH_IF_MCONT_EOB);

        pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, buffer_num);
}

static u32 pch_can_get_rx_buffer_link(struct pch_can_priv *priv, u32 buffer_num)
{
        u32 link;

        iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[0].cmask);
        pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, buffer_num);

        if (ioread32(&priv->regs->ifregs[0].mcont) & PCH_IF_MCONT_EOB)
                link = 0;
        else
                link = 1;
        return link;
}

static int pch_can_get_buffer_status(struct pch_can_priv *priv)
{
        return (ioread32(&priv->regs->treq1) & 0xffff) |
               (ioread32(&priv->regs->treq2) << 16);
}

static int pch_can_suspend(struct pci_dev *pdev, pm_message_t state)
{
        int i;
        int retval;
        u32 buf_stat;   /* Variable for reading the transmit buffer status. */
        int counter = PCH_COUNTER_LIMIT;

        struct net_device *dev = pci_get_drvdata(pdev);
        struct pch_can_priv *priv = netdev_priv(dev);

        /* Stop the CAN controller */
        pch_can_set_run_mode(priv, PCH_CAN_STOP);

        /* Indicate that we are aboutto/in suspend */
        priv->can.state = CAN_STATE_STOPPED;

        /* Waiting for all transmission to complete. */
        while (counter) {
                buf_stat = pch_can_get_buffer_status(priv);
                if (!buf_stat)
                        break;
                counter--;
                udelay(1);
        }
        if (!counter)
                dev_err(&pdev->dev, "%s -> Transmission time out.\n", __func__);

        /* Save interrupt configuration and then disable them */
        priv->int_enables = pch_can_get_int_enables(priv);
        pch_can_set_int_enables(priv, PCH_CAN_DISABLE);

        /* Save Tx buffer enable state */
        for (i = PCH_TX_OBJ_START; i <= PCH_TX_OBJ_END; i++)
                priv->tx_enable[i - 1] = pch_can_get_rxtx_ir(priv, i,
                                                             PCH_TX_IFREG);

        /* Disable all Transmit buffers */
        pch_can_set_tx_all(priv, 0);

        /* Save Rx buffer enable state */
        for (i = PCH_RX_OBJ_START; i <= PCH_RX_OBJ_END; i++) {
                priv->rx_enable[i - 1] = pch_can_get_rxtx_ir(priv, i,
                                                             PCH_RX_IFREG);
                priv->rx_link[i - 1] = pch_can_get_rx_buffer_link(priv, i);
        }

        /* Disable all Receive buffers */
        pch_can_set_rx_all(priv, 0);
        retval = pci_save_state(pdev);
        if (retval) {
                dev_err(&pdev->dev, "pci_save_state failed.\n");
        } else {
                pci_enable_wake(pdev, PCI_D3hot, 0);
                pci_disable_device(pdev);
                pci_set_power_state(pdev, pci_choose_state(pdev, state));
        }

        return retval;
}

static int pch_can_resume(struct pci_dev *pdev)
{
        int i;
        int retval;
        struct net_device *dev = pci_get_drvdata(pdev);
        struct pch_can_priv *priv = netdev_priv(dev);

        pci_set_power_state(pdev, PCI_D0);
        pci_restore_state(pdev);
        retval = pci_enable_device(pdev);
        if (retval) {
                dev_err(&pdev->dev, "pci_enable_device failed.\n");
                return retval;
        }

        pci_enable_wake(pdev, PCI_D3hot, 0);

        priv->can.state = CAN_STATE_ERROR_ACTIVE;

        /* Disabling all interrupts. */
        pch_can_set_int_enables(priv, PCH_CAN_DISABLE);

        /* Setting the CAN device in Stop Mode. */
        pch_can_set_run_mode(priv, PCH_CAN_STOP);

        /* Configuring the transmit and receive buffers. */
        pch_can_config_rx_tx_buffers(priv);

        /* Restore the CAN state */
        pch_set_bittiming(dev);

        /* Listen/Active */
        pch_can_set_optmode(priv);

        /* Enabling the transmit buffer. */
        for (i = PCH_TX_OBJ_START; i <= PCH_TX_OBJ_END; i++)
                pch_can_set_rxtx(priv, i, priv->tx_enable[i - 1], PCH_TX_IFREG);

        /* Configuring the receive buffer and enabling them. */
        for (i = PCH_RX_OBJ_START; i <= PCH_RX_OBJ_END; i++) {
                /* Restore buffer link */
                pch_can_set_rx_buffer_link(priv, i, priv->rx_link[i - 1]);

                /* Restore buffer enables */
                pch_can_set_rxtx(priv, i, priv->rx_enable[i - 1], PCH_RX_IFREG);
        }

        /* Enable CAN Interrupts */
        pch_can_set_int_custom(priv);

        /* Restore Run Mode */
        pch_can_set_run_mode(priv, PCH_CAN_RUN);

        return retval;
}
#else
#define pch_can_suspend NULL
#define pch_can_resume NULL
#endif

static int pch_can_get_berr_counter(const struct net_device *dev,
                                    struct can_berr_counter *bec)
{
        struct pch_can_priv *priv = netdev_priv(dev);
        u32 errc = ioread32(&priv->regs->errc);

        bec->txerr = errc & PCH_TEC;
        bec->rxerr = (errc & PCH_REC) >> 8;

        return 0;
}

static int pch_can_probe(struct pci_dev *pdev,
                                   const struct pci_device_id *id)
{
        struct net_device *ndev;
        struct pch_can_priv *priv;
        int rc;
        void __iomem *addr;

        rc = pci_enable_device(pdev);
        if (rc) {
                dev_err(&pdev->dev, "Failed pci_enable_device %d\n", rc);
                goto probe_exit_endev;
        }

        rc = pci_request_regions(pdev, KBUILD_MODNAME);
        if (rc) {
                dev_err(&pdev->dev, "Failed pci_request_regions %d\n", rc);
                goto probe_exit_pcireq;
        }

        addr = pci_iomap(pdev, 1, 0);
        if (!addr) {
                rc = -EIO;
                dev_err(&pdev->dev, "Failed pci_iomap\n");
                goto probe_exit_ipmap;
        }

        ndev = alloc_candev(sizeof(struct pch_can_priv), PCH_TX_OBJ_END);
        if (!ndev) {
                rc = -ENOMEM;
                dev_err(&pdev->dev, "Failed alloc_candev\n");
                goto probe_exit_alloc_candev;
        }

        priv = netdev_priv(ndev);
        priv->ndev = ndev;
        priv->regs = addr;
        priv->dev = pdev;
        priv->can.bittiming_const = &pch_can_bittiming_const;
        priv->can.do_set_mode = pch_can_do_set_mode;
        priv->can.do_get_berr_counter = pch_can_get_berr_counter;
        priv->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY |
                                       CAN_CTRLMODE_LOOPBACK;
        priv->tx_obj = PCH_TX_OBJ_START; /* Point head of Tx Obj */

        ndev->irq = pdev->irq;
        ndev->flags |= IFF_ECHO;

        pci_set_drvdata(pdev, ndev);
        SET_NETDEV_DEV(ndev, &pdev->dev);
        ndev->netdev_ops = &pch_can_netdev_ops;
        priv->can.clock.freq = PCH_CAN_CLK; /* Hz */

        netif_napi_add(ndev, &priv->napi, pch_can_poll, PCH_RX_OBJ_END);

        rc = pci_enable_msi(priv->dev);
        if (rc) {
                netdev_err(ndev, "PCH CAN opened without MSI\n");
                priv->use_msi = 0;
        } else {
                netdev_err(ndev, "PCH CAN opened with MSI\n");
                pci_set_master(pdev);
                priv->use_msi = 1;
        }

        rc = register_candev(ndev);
        if (rc) {
                dev_err(&pdev->dev, "Failed register_candev %d\n", rc);
                goto probe_exit_reg_candev;
        }

        return 0;

probe_exit_reg_candev:
        if (priv->use_msi)
                pci_disable_msi(priv->dev);
        free_candev(ndev);
probe_exit_alloc_candev:
        pci_iounmap(pdev, addr);
probe_exit_ipmap:
        pci_release_regions(pdev);
probe_exit_pcireq:
        pci_disable_device(pdev);
probe_exit_endev:
        return rc;
}

static struct pci_driver pch_can_pci_driver = {
        .name = "pch_can",
        .id_table = pch_pci_tbl,
        .probe = pch_can_probe,
        .remove = pch_can_remove,
        .suspend = pch_can_suspend,
        .resume = pch_can_resume,
};

module_pci_driver(pch_can_pci_driver);

MODULE_DESCRIPTION("Intel EG20T PCH CAN(Controller Area Network) Driver");
MODULE_LICENSE("GPL v2");
MODULE_VERSION("0.94");