// SPDX-License-Identifier: GPL-2.0-only
/*
 * Core driver for the CC770 and AN82527 CAN controllers
 *
 * Copyright (C) 2009, 2011 Wolfgang Grandegger <wg@grandegger.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/skbuff.h>
#include <linux/delay.h>

#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/error.h>
#include <linux/can/platform/cc770.h>

#include "cc770.h"

MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION(KBUILD_MODNAME "CAN netdevice driver");

/*
 * The CC770 is a CAN controller from Bosch, which is 100% compatible
 * with the AN82527 from Intel, but with "bugs" being fixed and some
 * additional functionality, mainly:
 *
 * 1. RX and TX error counters are readable.
 * 2. Support of silent (listen-only) mode.
 * 3. Message object 15 can receive all types of frames, also RTR and EFF.
 *
 * Details are available from Bosch's "CC770_Product_Info_2007-01.pdf",
 * which explains in detail the compatibility between the CC770 and the
 * 82527. This driver use the additional functionality 3. on real CC770
 * devices. Unfortunately, the CC770 does still not store the message
 * identifier of received remote transmission request frames and
 * therefore it's set to 0.
 *
 * The message objects 1..14 can be used for TX and RX while the message
 * objects 15 is optimized for RX. It has a shadow register for reliable
 * data reception under heavy bus load. Therefore it makes sense to use
 * this message object for the needed use case. The frame type (EFF/SFF)
 * for the message object 15 can be defined via kernel module parameter
 * "msgobj15_eff". If not equal 0, it will receive 29-bit EFF frames,
 * otherwise 11 bit SFF messages.
 */
static int msgobj15_eff;
module_param(msgobj15_eff, int, 0444);
MODULE_PARM_DESC(msgobj15_eff, "Extended 29-bit frames for message object 15 "
                 "(default: 11-bit standard frames)");

static int i82527_compat;
module_param(i82527_compat, int, 0444);
MODULE_PARM_DESC(i82527_compat, "Strict Intel 82527 compatibility mode "
                 "without using additional functions");

/*
 * This driver uses the last 5 message objects 11..15. The definitions
 * and structure below allows to configure and assign them to the real
 * message object.
 */
static unsigned char cc770_obj_flags[CC770_OBJ_MAX] = {
        [CC770_OBJ_RX0] = CC770_OBJ_FLAG_RX,
        [CC770_OBJ_RX1] = CC770_OBJ_FLAG_RX | CC770_OBJ_FLAG_EFF,
        [CC770_OBJ_RX_RTR0] = CC770_OBJ_FLAG_RX | CC770_OBJ_FLAG_RTR,
        [CC770_OBJ_RX_RTR1] = CC770_OBJ_FLAG_RX | CC770_OBJ_FLAG_RTR |
                              CC770_OBJ_FLAG_EFF,
        [CC770_OBJ_TX] = 0,
};

static const struct can_bittiming_const cc770_bittiming_const = {
        .name = KBUILD_MODNAME,
        .tseg1_min = 1,
        .tseg1_max = 16,
        .tseg2_min = 1,
        .tseg2_max = 8,
        .sjw_max = 4,
        .brp_min = 1,
        .brp_max = 64,
        .brp_inc = 1,
};

static inline int intid2obj(unsigned int intid)
{
        if (intid == 2)
                return 0;
        else
                return MSGOBJ_LAST + 2 - intid;
}

static void enable_all_objs(const struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);
        u8 msgcfg;
        unsigned char obj_flags;
        unsigned int o, mo;

        for (o = 0; o < ARRAY_SIZE(priv->obj_flags); o++) {
                obj_flags = priv->obj_flags[o];
                mo = obj2msgobj(o);

                if (obj_flags & CC770_OBJ_FLAG_RX) {
                        /*
                         * We don't need extra objects for RTR and EFF if
                         * the additional CC770 functions are enabled.
                         */
                        if (priv->control_normal_mode & CTRL_EAF) {
                                if (o > 0)
                                        continue;
                                netdev_dbg(dev, "Message object %d for "
                                           "RX data, RTR, SFF and EFF\n", mo);
                        } else {
                                netdev_dbg(dev,
                                           "Message object %d for RX %s %s\n",
                                           mo, obj_flags & CC770_OBJ_FLAG_RTR ?
                                           "RTR" : "data",
                                           obj_flags & CC770_OBJ_FLAG_EFF ?
                                           "EFF" : "SFF");
                        }

                        if (obj_flags & CC770_OBJ_FLAG_EFF)
                                msgcfg = MSGCFG_XTD;
                        else
                                msgcfg = 0;
                        if (obj_flags & CC770_OBJ_FLAG_RTR)
                                msgcfg |= MSGCFG_DIR;

                        cc770_write_reg(priv, msgobj[mo].config, msgcfg);
                        cc770_write_reg(priv, msgobj[mo].ctrl0,
                                        MSGVAL_SET | TXIE_RES |
                                        RXIE_SET | INTPND_RES);

                        if (obj_flags & CC770_OBJ_FLAG_RTR)
                                cc770_write_reg(priv, msgobj[mo].ctrl1,
                                                NEWDAT_RES | CPUUPD_SET |
                                                TXRQST_RES | RMTPND_RES);
                        else
                                cc770_write_reg(priv, msgobj[mo].ctrl1,
                                                NEWDAT_RES | MSGLST_RES |
                                                TXRQST_RES | RMTPND_RES);
                } else {
                        netdev_dbg(dev, "Message object %d for "
                                   "TX data, RTR, SFF and EFF\n", mo);

                        cc770_write_reg(priv, msgobj[mo].ctrl1,
                                        RMTPND_RES | TXRQST_RES |
                                        CPUUPD_RES | NEWDAT_RES);
                        cc770_write_reg(priv, msgobj[mo].ctrl0,
                                        MSGVAL_RES | TXIE_RES |
                                        RXIE_RES | INTPND_RES);
                }
        }
}

static void disable_all_objs(const struct cc770_priv *priv)
{
        int o, mo;

        for (o = 0; o <  ARRAY_SIZE(priv->obj_flags); o++) {
                mo = obj2msgobj(o);

                if (priv->obj_flags[o] & CC770_OBJ_FLAG_RX) {
                        if (o > 0 && priv->control_normal_mode & CTRL_EAF)
                                continue;

                        cc770_write_reg(priv, msgobj[mo].ctrl1,
                                        NEWDAT_RES | MSGLST_RES |
                                        TXRQST_RES | RMTPND_RES);
                        cc770_write_reg(priv, msgobj[mo].ctrl0,
                                        MSGVAL_RES | TXIE_RES |
                                        RXIE_RES | INTPND_RES);
                } else {
                        /* Clear message object for send */
                        cc770_write_reg(priv, msgobj[mo].ctrl1,
                                        RMTPND_RES | TXRQST_RES |
                                        CPUUPD_RES | NEWDAT_RES);
                        cc770_write_reg(priv, msgobj[mo].ctrl0,
                                        MSGVAL_RES | TXIE_RES |
                                        RXIE_RES | INTPND_RES);
                }
        }
}

static void set_reset_mode(struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);

        /* Enable configuration and puts chip in bus-off, disable interrupts */
        cc770_write_reg(priv, control, CTRL_CCE | CTRL_INI);

        priv->can.state = CAN_STATE_STOPPED;

        /* Clear interrupts */
        cc770_read_reg(priv, interrupt);

        /* Clear status register */
        cc770_write_reg(priv, status, 0);

        /* Disable all used message objects */
        disable_all_objs(priv);
}

static void set_normal_mode(struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);

        /* Clear interrupts */
        cc770_read_reg(priv, interrupt);

        /* Clear status register and pre-set last error code */
        cc770_write_reg(priv, status, STAT_LEC_MASK);

        /* Enable all used message objects*/
        enable_all_objs(dev);

        /*
         * Clear bus-off, interrupts only for errors,
         * not for status change
         */
        cc770_write_reg(priv, control, priv->control_normal_mode);

        priv->can.state = CAN_STATE_ERROR_ACTIVE;
}

static void chipset_init(struct cc770_priv *priv)
{
        int mo, id, data;

        /* Enable configuration and put chip in bus-off, disable interrupts */
        cc770_write_reg(priv, control, (CTRL_CCE | CTRL_INI));

        /* Set CLKOUT divider and slew rates */
        cc770_write_reg(priv, clkout, priv->clkout);

        /* Configure CPU interface / CLKOUT enable */
        cc770_write_reg(priv, cpu_interface, priv->cpu_interface);

        /* Set bus configuration  */
        cc770_write_reg(priv, bus_config, priv->bus_config);

        /* Clear interrupts */
        cc770_read_reg(priv, interrupt);

        /* Clear status register */
        cc770_write_reg(priv, status, 0);

        /* Clear and invalidate message objects */
        for (mo = MSGOBJ_FIRST; mo <= MSGOBJ_LAST; mo++) {
                cc770_write_reg(priv, msgobj[mo].ctrl0,
                                INTPND_UNC | RXIE_RES |
                                TXIE_RES | MSGVAL_RES);
                cc770_write_reg(priv, msgobj[mo].ctrl0,
                                INTPND_RES | RXIE_RES |
                                TXIE_RES | MSGVAL_RES);
                cc770_write_reg(priv, msgobj[mo].ctrl1,
                                NEWDAT_RES | MSGLST_RES |
                                TXRQST_RES | RMTPND_RES);
                for (data = 0; data < 8; data++)
                        cc770_write_reg(priv, msgobj[mo].data[data], 0);
                for (id = 0; id < 4; id++)
                        cc770_write_reg(priv, msgobj[mo].id[id], 0);
                cc770_write_reg(priv, msgobj[mo].config, 0);
        }

        /* Set all global ID masks to "don't care" */
        cc770_write_reg(priv, global_mask_std[0], 0);
        cc770_write_reg(priv, global_mask_std[1], 0);
        cc770_write_reg(priv, global_mask_ext[0], 0);
        cc770_write_reg(priv, global_mask_ext[1], 0);
        cc770_write_reg(priv, global_mask_ext[2], 0);
        cc770_write_reg(priv, global_mask_ext[3], 0);

}

static int cc770_probe_chip(struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);

        /* Enable configuration, put chip in bus-off, disable ints */
        cc770_write_reg(priv, control, CTRL_CCE | CTRL_EAF | CTRL_INI);
        /* Configure cpu interface / CLKOUT disable */
        cc770_write_reg(priv, cpu_interface, priv->cpu_interface);

        /*
         * Check if hardware reset is still inactive or maybe there
         * is no chip in this address space
         */
        if (cc770_read_reg(priv, cpu_interface) & CPUIF_RST) {
                netdev_info(dev, "probing @0x%p failed (reset)\n",
                            priv->reg_base);
                return -ENODEV;
        }

        /* Write and read back test pattern (some arbitrary values) */
        cc770_write_reg(priv, msgobj[1].data[1], 0x25);
        cc770_write_reg(priv, msgobj[2].data[3], 0x52);
        cc770_write_reg(priv, msgobj[10].data[6], 0xc3);
        if ((cc770_read_reg(priv, msgobj[1].data[1]) != 0x25) ||
            (cc770_read_reg(priv, msgobj[2].data[3]) != 0x52) ||
            (cc770_read_reg(priv, msgobj[10].data[6]) != 0xc3)) {
                netdev_info(dev, "probing @0x%p failed (pattern)\n",
                            priv->reg_base);
                return -ENODEV;
        }

        /* Check if this chip is a CC770 supporting additional functions */
        if (cc770_read_reg(priv, control) & CTRL_EAF)
                priv->control_normal_mode |= CTRL_EAF;

        return 0;
}

static void cc770_start(struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);

        /* leave reset mode */
        if (priv->can.state != CAN_STATE_STOPPED)
                set_reset_mode(dev);

        /* leave reset mode */
        set_normal_mode(dev);
}

static int cc770_set_mode(struct net_device *dev, enum can_mode mode)
{
        switch (mode) {
        case CAN_MODE_START:
                cc770_start(dev);
                netif_wake_queue(dev);
                break;

        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int cc770_set_bittiming(struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);
        struct can_bittiming *bt = &priv->can.bittiming;
        u8 btr0, btr1;

        btr0 = ((bt->brp - 1) & 0x3f) | (((bt->sjw - 1) & 0x3) << 6);
        btr1 = ((bt->prop_seg + bt->phase_seg1 - 1) & 0xf) |
                (((bt->phase_seg2 - 1) & 0x7) << 4);
        if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
                btr1 |= 0x80;

        netdev_info(dev, "setting BTR0=0x%02x BTR1=0x%02x\n", btr0, btr1);

        cc770_write_reg(priv, bit_timing_0, btr0);
        cc770_write_reg(priv, bit_timing_1, btr1);

        return 0;
}

static int cc770_get_berr_counter(const struct net_device *dev,
                                  struct can_berr_counter *bec)
{
        struct cc770_priv *priv = netdev_priv(dev);

        bec->txerr = cc770_read_reg(priv, tx_error_counter);
        bec->rxerr = cc770_read_reg(priv, rx_error_counter);

        return 0;
}

static void cc770_tx(struct net_device *dev, int mo)
{
        struct cc770_priv *priv = netdev_priv(dev);
        struct can_frame *cf = (struct can_frame *)priv->tx_skb->data;
        u8 dlc, rtr;
        u32 id;
        int i;

        dlc = cf->len;
        id = cf->can_id;
        rtr = cf->can_id & CAN_RTR_FLAG ? 0 : MSGCFG_DIR;

        cc770_write_reg(priv, msgobj[mo].ctrl0,
                        MSGVAL_RES | TXIE_RES | RXIE_RES | INTPND_RES);
        cc770_write_reg(priv, msgobj[mo].ctrl1,
                        RMTPND_RES | TXRQST_RES | CPUUPD_SET | NEWDAT_RES);

        if (id & CAN_EFF_FLAG) {
                id &= CAN_EFF_MASK;
                cc770_write_reg(priv, msgobj[mo].config,
                                (dlc << 4) | rtr | MSGCFG_XTD);
                cc770_write_reg(priv, msgobj[mo].id[3], id << 3);
                cc770_write_reg(priv, msgobj[mo].id[2], id >> 5);
                cc770_write_reg(priv, msgobj[mo].id[1], id >> 13);
                cc770_write_reg(priv, msgobj[mo].id[0], id >> 21);
        } else {
                id &= CAN_SFF_MASK;
                cc770_write_reg(priv, msgobj[mo].config, (dlc << 4) | rtr);
                cc770_write_reg(priv, msgobj[mo].id[0], id >> 3);
                cc770_write_reg(priv, msgobj[mo].id[1], id << 5);
        }

        for (i = 0; i < dlc; i++)
                cc770_write_reg(priv, msgobj[mo].data[i], cf->data[i]);

        cc770_write_reg(priv, msgobj[mo].ctrl1,
                        RMTPND_UNC | TXRQST_SET | CPUUPD_RES | NEWDAT_UNC);
        cc770_write_reg(priv, msgobj[mo].ctrl0,
                        MSGVAL_SET | TXIE_SET | RXIE_SET | INTPND_UNC);
}

static netdev_tx_t cc770_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);
        unsigned int mo = obj2msgobj(CC770_OBJ_TX);

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

        netif_stop_queue(dev);

        if ((cc770_read_reg(priv,
                            msgobj[mo].ctrl1) & TXRQST_UNC) == TXRQST_SET) {
                netdev_err(dev, "TX register is still occupied!\n");
                return NETDEV_TX_BUSY;
        }

        priv->tx_skb = skb;
        cc770_tx(dev, mo);

        return NETDEV_TX_OK;
}

static void cc770_rx(struct net_device *dev, unsigned int mo, u8 ctrl1)
{
        struct cc770_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        struct can_frame *cf;
        struct sk_buff *skb;
        u8 config;
        u32 id;
        int i;

        skb = alloc_can_skb(dev, &cf);
        if (!skb)
                return;

        config = cc770_read_reg(priv, msgobj[mo].config);

        if (ctrl1 & RMTPND_SET) {
                /*
                 * Unfortunately, the chip does not store the real message
                 * identifier of the received remote transmission request
                 * frame. Therefore we set it to 0.
                 */
                cf->can_id = CAN_RTR_FLAG;
                if (config & MSGCFG_XTD)
                        cf->can_id |= CAN_EFF_FLAG;
                cf->len = 0;
        } else {
                if (config & MSGCFG_XTD) {
                        id = cc770_read_reg(priv, msgobj[mo].id[3]);
                        id |= cc770_read_reg(priv, msgobj[mo].id[2]) << 8;
                        id |= cc770_read_reg(priv, msgobj[mo].id[1]) << 16;
                        id |= cc770_read_reg(priv, msgobj[mo].id[0]) << 24;
                        id >>= 3;
                        id |= CAN_EFF_FLAG;
                } else {
                        id = cc770_read_reg(priv, msgobj[mo].id[1]);
                        id |= cc770_read_reg(priv, msgobj[mo].id[0]) << 8;
                        id >>= 5;
                }

                cf->can_id = id;
                cf->len = can_cc_dlc2len((config & 0xf0) >> 4);
                for (i = 0; i < cf->len; i++)
                        cf->data[i] = cc770_read_reg(priv, msgobj[mo].data[i]);
        }

        stats->rx_packets++;
        stats->rx_bytes += cf->len;
        netif_rx(skb);
}

static int cc770_err(struct net_device *dev, u8 status)
{
        struct cc770_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        struct can_frame *cf;
        struct sk_buff *skb;
        u8 lec;

        netdev_dbg(dev, "status interrupt (%#x)\n", status);

        skb = alloc_can_err_skb(dev, &cf);
        if (!skb)
                return -ENOMEM;

        /* Use extended functions of the CC770 */
        if (priv->control_normal_mode & CTRL_EAF) {
                cf->data[6] = cc770_read_reg(priv, tx_error_counter);
                cf->data[7] = cc770_read_reg(priv, rx_error_counter);
        }

        if (status & STAT_BOFF) {
                /* Disable interrupts */
                cc770_write_reg(priv, control, CTRL_INI);
                cf->can_id |= CAN_ERR_BUSOFF;
                priv->can.state = CAN_STATE_BUS_OFF;
                priv->can.can_stats.bus_off++;
                can_bus_off(dev);
        } else if (status & STAT_WARN) {
                cf->can_id |= CAN_ERR_CRTL;
                /* Only the CC770 does show error passive */
                if (cf->data[7] > 127) {
                        cf->data[1] = CAN_ERR_CRTL_RX_PASSIVE |
                                CAN_ERR_CRTL_TX_PASSIVE;
                        priv->can.state = CAN_STATE_ERROR_PASSIVE;
                        priv->can.can_stats.error_passive++;
                } else {
                        cf->data[1] = CAN_ERR_CRTL_RX_WARNING |
                                CAN_ERR_CRTL_TX_WARNING;
                        priv->can.state = CAN_STATE_ERROR_WARNING;
                        priv->can.can_stats.error_warning++;
                }
        } else {
                /* Back to error active */
                cf->can_id |= CAN_ERR_PROT;
                cf->data[2] = CAN_ERR_PROT_ACTIVE;
                priv->can.state = CAN_STATE_ERROR_ACTIVE;
        }

        lec = status & STAT_LEC_MASK;
        if (lec < 7 && lec > 0) {
                if (lec == STAT_LEC_ACK) {
                        cf->can_id |= CAN_ERR_ACK;
                } else {
                        cf->can_id |= CAN_ERR_PROT;
                        switch (lec) {
                        case STAT_LEC_STUFF:
                                cf->data[2] |= CAN_ERR_PROT_STUFF;
                                break;
                        case STAT_LEC_FORM:
                                cf->data[2] |= CAN_ERR_PROT_FORM;
                                break;
                        case STAT_LEC_BIT1:
                                cf->data[2] |= CAN_ERR_PROT_BIT1;
                                break;
                        case STAT_LEC_BIT0:
                                cf->data[2] |= CAN_ERR_PROT_BIT0;
                                break;
                        case STAT_LEC_CRC:
                                cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ;
                                break;
                        }
                }
        }


        stats->rx_packets++;
        stats->rx_bytes += cf->len;
        netif_rx(skb);

        return 0;
}

static int cc770_status_interrupt(struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);
        u8 status;

        status = cc770_read_reg(priv, status);
        /* Reset the status register including RXOK and TXOK */
        cc770_write_reg(priv, status, STAT_LEC_MASK);

        if (status & (STAT_WARN | STAT_BOFF) ||
            (status & STAT_LEC_MASK) != STAT_LEC_MASK) {
                cc770_err(dev, status);
                return status & STAT_BOFF;
        }

        return 0;
}

static void cc770_rx_interrupt(struct net_device *dev, unsigned int o)
{
        struct cc770_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        unsigned int mo = obj2msgobj(o);
        u8 ctrl1;
        int n = CC770_MAX_MSG;

        while (n--) {
                ctrl1 = cc770_read_reg(priv, msgobj[mo].ctrl1);

                if (!(ctrl1 & NEWDAT_SET))  {
                        /* Check for RTR if additional functions are enabled */
                        if (priv->control_normal_mode & CTRL_EAF) {
                                if (!(cc770_read_reg(priv, msgobj[mo].ctrl0) &
                                      INTPND_SET))
                                        break;
                        } else {
                                break;
                        }
                }

                if (ctrl1 & MSGLST_SET) {
                        stats->rx_over_errors++;
                        stats->rx_errors++;
                }
                if (mo < MSGOBJ_LAST)
                        cc770_write_reg(priv, msgobj[mo].ctrl1,
                                        NEWDAT_RES | MSGLST_RES |
                                        TXRQST_UNC | RMTPND_UNC);
                cc770_rx(dev, mo, ctrl1);

                cc770_write_reg(priv, msgobj[mo].ctrl0,
                                MSGVAL_SET | TXIE_RES |
                                RXIE_SET | INTPND_RES);
                cc770_write_reg(priv, msgobj[mo].ctrl1,
                                NEWDAT_RES | MSGLST_RES |
                                TXRQST_RES | RMTPND_RES);
        }
}

static void cc770_rtr_interrupt(struct net_device *dev, unsigned int o)
{
        struct cc770_priv *priv = netdev_priv(dev);
        unsigned int mo = obj2msgobj(o);
        u8 ctrl0, ctrl1;
        int n = CC770_MAX_MSG;

        while (n--) {
                ctrl0 = cc770_read_reg(priv, msgobj[mo].ctrl0);
                if (!(ctrl0 & INTPND_SET))
                        break;

                ctrl1 = cc770_read_reg(priv, msgobj[mo].ctrl1);
                cc770_rx(dev, mo, ctrl1);

                cc770_write_reg(priv, msgobj[mo].ctrl0,
                                MSGVAL_SET | TXIE_RES |
                                RXIE_SET | INTPND_RES);
                cc770_write_reg(priv, msgobj[mo].ctrl1,
                                NEWDAT_RES | CPUUPD_SET |
                                TXRQST_RES | RMTPND_RES);
        }
}

static void cc770_tx_interrupt(struct net_device *dev, unsigned int o)
{
        struct cc770_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        unsigned int mo = obj2msgobj(o);
        struct can_frame *cf;
        u8 ctrl1;

        ctrl1 = cc770_read_reg(priv, msgobj[mo].ctrl1);

        cc770_write_reg(priv, msgobj[mo].ctrl0,
                        MSGVAL_RES | TXIE_RES | RXIE_RES | INTPND_RES);
        cc770_write_reg(priv, msgobj[mo].ctrl1,
                        RMTPND_RES | TXRQST_RES | MSGLST_RES | NEWDAT_RES);

        if (unlikely(!priv->tx_skb)) {
                netdev_err(dev, "missing tx skb in tx interrupt\n");
                return;
        }

        if (unlikely(ctrl1 & MSGLST_SET)) {
                stats->rx_over_errors++;
                stats->rx_errors++;
        }

        /* When the CC770 is sending an RTR message and it receives a regular
         * message that matches the id of the RTR message, it will overwrite the
         * outgoing message in the TX register. When this happens we must
         * process the received message and try to transmit the outgoing skb
         * again.
         */
        if (unlikely(ctrl1 & NEWDAT_SET)) {
                cc770_rx(dev, mo, ctrl1);
                cc770_tx(dev, mo);
                return;
        }

        cf = (struct can_frame *)priv->tx_skb->data;
        stats->tx_bytes += cf->len;
        stats->tx_packets++;

        can_put_echo_skb(priv->tx_skb, dev, 0, 0);
        can_get_echo_skb(dev, 0, NULL);
        priv->tx_skb = NULL;

        netif_wake_queue(dev);
}

static irqreturn_t cc770_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = (struct net_device *)dev_id;
        struct cc770_priv *priv = netdev_priv(dev);
        u8 intid;
        int o, n = 0;

        /* Shared interrupts and IRQ off? */
        if (priv->can.state == CAN_STATE_STOPPED)
                return IRQ_NONE;

        if (priv->pre_irq)
                priv->pre_irq(priv);

        while (n < CC770_MAX_IRQ) {
                /* Read the highest pending interrupt request */
                intid = cc770_read_reg(priv, interrupt);
                if (!intid)
                        break;
                n++;

                if (intid == 1) {
                        /* Exit in case of bus-off */
                        if (cc770_status_interrupt(dev))
                                break;
                } else {
                        o = intid2obj(intid);

                        if (o >= CC770_OBJ_MAX) {
                                netdev_err(dev, "Unexpected interrupt id %d\n",
                                           intid);
                                continue;
                        }

                        if (priv->obj_flags[o] & CC770_OBJ_FLAG_RTR)
                                cc770_rtr_interrupt(dev, o);
                        else if (priv->obj_flags[o] & CC770_OBJ_FLAG_RX)
                                cc770_rx_interrupt(dev, o);
                        else
                                cc770_tx_interrupt(dev, o);
                }
        }

        if (priv->post_irq)
                priv->post_irq(priv);

        if (n >= CC770_MAX_IRQ)
                netdev_dbg(dev, "%d messages handled in ISR", n);

        return (n) ? IRQ_HANDLED : IRQ_NONE;
}

static int cc770_open(struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);
        int err;

        /* set chip into reset mode */
        set_reset_mode(dev);

        /* common open */
        err = open_candev(dev);
        if (err)
                return err;

        err = request_irq(dev->irq, &cc770_interrupt, priv->irq_flags,
                          dev->name, dev);
        if (err) {
                close_candev(dev);
                return -EAGAIN;
        }

        /* init and start chip */
        cc770_start(dev);

        netif_start_queue(dev);

        return 0;
}

static int cc770_close(struct net_device *dev)
{
        netif_stop_queue(dev);
        set_reset_mode(dev);

        free_irq(dev->irq, dev);
        close_candev(dev);

        return 0;
}

struct net_device *alloc_cc770dev(int sizeof_priv)
{
        struct net_device *dev;
        struct cc770_priv *priv;

        dev = alloc_candev(sizeof(struct cc770_priv) + sizeof_priv,
                           CC770_ECHO_SKB_MAX);
        if (!dev)
                return NULL;

        priv = netdev_priv(dev);

        priv->dev = dev;
        priv->can.bittiming_const = &cc770_bittiming_const;
        priv->can.do_set_bittiming = cc770_set_bittiming;
        priv->can.do_set_mode = cc770_set_mode;
        priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES;
        priv->tx_skb = NULL;

        memcpy(priv->obj_flags, cc770_obj_flags, sizeof(cc770_obj_flags));

        if (sizeof_priv)
                priv->priv = (void *)priv + sizeof(struct cc770_priv);

        return dev;
}
EXPORT_SYMBOL_GPL(alloc_cc770dev);

void free_cc770dev(struct net_device *dev)
{
        free_candev(dev);
}
EXPORT_SYMBOL_GPL(free_cc770dev);

static const struct net_device_ops cc770_netdev_ops = {
        .ndo_open = cc770_open,
        .ndo_stop = cc770_close,
        .ndo_start_xmit = cc770_start_xmit,
        .ndo_change_mtu = can_change_mtu,
};

int register_cc770dev(struct net_device *dev)
{
        struct cc770_priv *priv = netdev_priv(dev);
        int err;

        err = cc770_probe_chip(dev);
        if (err)
                return err;

        dev->netdev_ops = &cc770_netdev_ops;

        dev->flags |= IFF_ECHO; /* we support local echo */

        /* Should we use additional functions? */
        if (!i82527_compat && priv->control_normal_mode & CTRL_EAF) {
                priv->can.do_get_berr_counter = cc770_get_berr_counter;
                priv->control_normal_mode = CTRL_IE | CTRL_EAF | CTRL_EIE;
                netdev_dbg(dev, "i82527 mode with additional functions\n");
        } else {
                priv->control_normal_mode = CTRL_IE | CTRL_EIE;
                netdev_dbg(dev, "strict i82527 compatibility mode\n");
        }

        chipset_init(priv);
        set_reset_mode(dev);

        return register_candev(dev);
}
EXPORT_SYMBOL_GPL(register_cc770dev);

void unregister_cc770dev(struct net_device *dev)
{
        set_reset_mode(dev);
        unregister_candev(dev);
}
EXPORT_SYMBOL_GPL(unregister_cc770dev);

static __init int cc770_init(void)
{
        if (msgobj15_eff) {
                cc770_obj_flags[CC770_OBJ_RX0] |= CC770_OBJ_FLAG_EFF;
                cc770_obj_flags[CC770_OBJ_RX1] &= ~CC770_OBJ_FLAG_EFF;
        }

        pr_info("CAN netdevice driver\n");

        return 0;
}
module_init(cc770_init);

static __exit void cc770_exit(void)
{
        pr_info("driver removed\n");
}
module_exit(cc770_exit);