/*
 * sja1000.c -  Philips SJA1000 network device driver
 *
 * Copyright (c) 2003 Matthias Brukner, Trajet Gmbh, Rebenring 33,
 * 38106 Braunschweig, GERMANY
 *
 * Copyright (c) 2002-2007 Volkswagen Group Electronic Research
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Volkswagen nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * Alternatively, provided that this notice is retained in full, this
 * software may be distributed under the terms of the GNU General
 * Public License ("GPL") version 2, in which case the provisions of the
 * GPL apply INSTEAD OF those given above.
 *
 * The provided data structures and external interfaces from this code
 * are not restricted to be used by modules with a GPL compatible license.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 */

#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/ethtool.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/dev.h>
#include <linux/can/error.h>

#include "sja1000.h"

#define DRV_NAME "sja1000"

MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION(DRV_NAME "CAN netdevice driver");

static const struct can_bittiming_const sja1000_bittiming_const = {
        .name = DRV_NAME,
        .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 void sja1000_write_cmdreg(struct sja1000_priv *priv, u8 val)
{
        unsigned long flags;

        /*
         * The command register needs some locking and time to settle
         * the write_reg() operation - especially on SMP systems.
         */
        spin_lock_irqsave(&priv->cmdreg_lock, flags);
        priv->write_reg(priv, SJA1000_CMR, val);
        priv->read_reg(priv, SJA1000_SR);
        spin_unlock_irqrestore(&priv->cmdreg_lock, flags);
}

static int sja1000_is_absent(struct sja1000_priv *priv)
{
        return (priv->read_reg(priv, SJA1000_MOD) == 0xFF);
}

static int sja1000_probe_chip(struct net_device *dev)
{
        struct sja1000_priv *priv = netdev_priv(dev);

        if (priv->reg_base && sja1000_is_absent(priv)) {
                netdev_err(dev, "probing failed\n");
                return 0;
        }
        return -1;
}

static void set_reset_mode(struct net_device *dev)
{
        struct sja1000_priv *priv = netdev_priv(dev);
        unsigned char status = priv->read_reg(priv, SJA1000_MOD);
        int i;

        /* disable interrupts */
        priv->write_reg(priv, SJA1000_IER, IRQ_OFF);

        for (i = 0; i < 100; i++) {
                /* check reset bit */
                if (status & MOD_RM) {
                        priv->can.state = CAN_STATE_STOPPED;
                        return;
                }

                /* reset chip */
                priv->write_reg(priv, SJA1000_MOD, MOD_RM);
                udelay(10);
                status = priv->read_reg(priv, SJA1000_MOD);
        }

        netdev_err(dev, "setting SJA1000 into reset mode failed!\n");
}

static void set_normal_mode(struct net_device *dev)
{
        struct sja1000_priv *priv = netdev_priv(dev);
        unsigned char status = priv->read_reg(priv, SJA1000_MOD);
        u8 mod_reg_val = 0x00;
        int i;

        for (i = 0; i < 100; i++) {
                /* check reset bit */
                if ((status & MOD_RM) == 0) {
                        priv->can.state = CAN_STATE_ERROR_ACTIVE;
                        /* enable interrupts */
                        if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
                                priv->write_reg(priv, SJA1000_IER, IRQ_ALL);
                        else
                                priv->write_reg(priv, SJA1000_IER,
                                                IRQ_ALL & ~IRQ_BEI);
                        return;
                }

                /* set chip to normal mode */
                if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
                        mod_reg_val |= MOD_LOM;
                if (priv->can.ctrlmode & CAN_CTRLMODE_PRESUME_ACK)
                        mod_reg_val |= MOD_STM;
                priv->write_reg(priv, SJA1000_MOD, mod_reg_val);

                udelay(10);

                status = priv->read_reg(priv, SJA1000_MOD);
        }

        netdev_err(dev, "setting SJA1000 into normal mode failed!\n");
}

/*
 * initialize SJA1000 chip:
 *   - reset chip
 *   - set output mode
 *   - set baudrate
 *   - enable interrupts
 *   - start operating mode
 */
static void chipset_init(struct net_device *dev)
{
        struct sja1000_priv *priv = netdev_priv(dev);

        if (!(priv->flags & SJA1000_QUIRK_NO_CDR_REG))
                /* set clock divider and output control register */
                priv->write_reg(priv, SJA1000_CDR, priv->cdr | CDR_PELICAN);

        /* set acceptance filter (accept all) */
        priv->write_reg(priv, SJA1000_ACCC0, 0x00);
        priv->write_reg(priv, SJA1000_ACCC1, 0x00);
        priv->write_reg(priv, SJA1000_ACCC2, 0x00);
        priv->write_reg(priv, SJA1000_ACCC3, 0x00);

        priv->write_reg(priv, SJA1000_ACCM0, 0xFF);
        priv->write_reg(priv, SJA1000_ACCM1, 0xFF);
        priv->write_reg(priv, SJA1000_ACCM2, 0xFF);
        priv->write_reg(priv, SJA1000_ACCM3, 0xFF);

        priv->write_reg(priv, SJA1000_OCR, priv->ocr | OCR_MODE_NORMAL);
}

static void sja1000_start(struct net_device *dev)
{
        struct sja1000_priv *priv = netdev_priv(dev);

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

        /* Initialize chip if uninitialized at this stage */
        if (!(priv->flags & SJA1000_QUIRK_NO_CDR_REG ||
              priv->read_reg(priv, SJA1000_CDR) & CDR_PELICAN))
                chipset_init(dev);

        /* Clear error counters and error code capture */
        priv->write_reg(priv, SJA1000_TXERR, 0x0);
        priv->write_reg(priv, SJA1000_RXERR, 0x0);
        priv->read_reg(priv, SJA1000_ECC);

        /* clear interrupt flags */
        priv->read_reg(priv, SJA1000_IR);

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

static int sja1000_set_mode(struct net_device *dev, enum can_mode mode)
{
        switch (mode) {
        case CAN_MODE_START:
                sja1000_start(dev);
                if (netif_queue_stopped(dev))
                        netif_wake_queue(dev);
                break;

        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int sja1000_set_bittiming(struct net_device *dev)
{
        struct sja1000_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);

        priv->write_reg(priv, SJA1000_BTR0, btr0);
        priv->write_reg(priv, SJA1000_BTR1, btr1);

        return 0;
}

static int sja1000_get_berr_counter(const struct net_device *dev,
                                    struct can_berr_counter *bec)
{
        struct sja1000_priv *priv = netdev_priv(dev);

        bec->txerr = priv->read_reg(priv, SJA1000_TXERR);
        bec->rxerr = priv->read_reg(priv, SJA1000_RXERR);

        return 0;
}

/*
 * transmit a CAN message
 * message layout in the sk_buff should be like this:
 * xx xx xx xx   ff      ll   00 11 22 33 44 55 66 77
 * [  can-id ] [flags] [len] [can data (up to 8 bytes]
 */
static netdev_tx_t sja1000_start_xmit(struct sk_buff *skb,
                                            struct net_device *dev)
{
        struct sja1000_priv *priv = netdev_priv(dev);
        struct can_frame *cf = (struct can_frame *)skb->data;
        uint8_t fi;
        canid_t id;
        uint8_t dreg;
        u8 cmd_reg_val = 0x00;
        int i;

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

        netif_stop_queue(dev);

        fi = can_get_cc_dlc(cf, priv->can.ctrlmode);
        id = cf->can_id;

        if (id & CAN_RTR_FLAG)
                fi |= SJA1000_FI_RTR;

        if (id & CAN_EFF_FLAG) {
                fi |= SJA1000_FI_FF;
                dreg = SJA1000_EFF_BUF;
                priv->write_reg(priv, SJA1000_FI, fi);
                priv->write_reg(priv, SJA1000_ID1, (id & 0x1fe00000) >> 21);
                priv->write_reg(priv, SJA1000_ID2, (id & 0x001fe000) >> 13);
                priv->write_reg(priv, SJA1000_ID3, (id & 0x00001fe0) >> 5);
                priv->write_reg(priv, SJA1000_ID4, (id & 0x0000001f) << 3);
        } else {
                dreg = SJA1000_SFF_BUF;
                priv->write_reg(priv, SJA1000_FI, fi);
                priv->write_reg(priv, SJA1000_ID1, (id & 0x000007f8) >> 3);
                priv->write_reg(priv, SJA1000_ID2, (id & 0x00000007) << 5);
        }

        for (i = 0; i < cf->len; i++)
                priv->write_reg(priv, dreg++, cf->data[i]);

        can_put_echo_skb(skb, dev, 0, 0);

        if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
                cmd_reg_val |= CMD_AT;

        if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
                cmd_reg_val |= CMD_SRR;
        else
                cmd_reg_val |= CMD_TR;

        sja1000_write_cmdreg(priv, cmd_reg_val);

        return NETDEV_TX_OK;
}

static void sja1000_rx(struct net_device *dev)
{
        struct sja1000_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        struct can_frame *cf;
        struct sk_buff *skb;
        uint8_t fi;
        uint8_t dreg;
        canid_t id;
        int i;

        /* create zero'ed CAN frame buffer */
        skb = alloc_can_skb(dev, &cf);
        if (skb == NULL)
                return;

        fi = priv->read_reg(priv, SJA1000_FI);

        if (fi & SJA1000_FI_FF) {
                /* extended frame format (EFF) */
                dreg = SJA1000_EFF_BUF;
                id = (priv->read_reg(priv, SJA1000_ID1) << 21)
                    | (priv->read_reg(priv, SJA1000_ID2) << 13)
                    | (priv->read_reg(priv, SJA1000_ID3) << 5)
                    | (priv->read_reg(priv, SJA1000_ID4) >> 3);
                id |= CAN_EFF_FLAG;
        } else {
                /* standard frame format (SFF) */
                dreg = SJA1000_SFF_BUF;
                id = (priv->read_reg(priv, SJA1000_ID1) << 3)
                    | (priv->read_reg(priv, SJA1000_ID2) >> 5);
        }

        can_frame_set_cc_len(cf, fi & 0x0F, priv->can.ctrlmode);
        if (fi & SJA1000_FI_RTR) {
                id |= CAN_RTR_FLAG;
        } else {
                for (i = 0; i < cf->len; i++)
                        cf->data[i] = priv->read_reg(priv, dreg++);

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

        cf->can_id = id;

        /* release receive buffer */
        sja1000_write_cmdreg(priv, CMD_RRB);

        netif_rx(skb);
}

static irqreturn_t sja1000_reset_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = (struct net_device *)dev_id;

        netdev_dbg(dev, "performing a soft reset upon overrun\n");

        netif_tx_lock(dev);

        can_free_echo_skb(dev, 0, NULL);
        sja1000_set_mode(dev, CAN_MODE_START);

        netif_tx_unlock(dev);

        return IRQ_HANDLED;
}

static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
{
        struct sja1000_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        enum can_state state, rx_state, tx_state;
        struct can_frame *cf;
        struct sk_buff *skb;
        struct can_berr_counter bec;
        uint8_t ecc, alc;
        int ret = 0;

        skb = alloc_can_err_skb(dev, &cf);

        sja1000_get_berr_counter(dev, &bec);
        can_state_get_by_berr_counter(dev, &bec, &tx_state, &rx_state);

        if (status & SR_BS)
                rx_state = CAN_STATE_BUS_OFF;

        state = max(tx_state, rx_state);

        if (isrc & IRQ_DOI) {
                /* data overrun interrupt */
                netdev_dbg(dev, "data overrun interrupt\n");
                if (skb) {
                        cf->can_id |= CAN_ERR_CRTL;
                        cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
                }

                stats->rx_over_errors++;
                stats->rx_errors++;
                sja1000_write_cmdreg(priv, CMD_CDO);    /* clear bit */

                /* Some controllers needs additional handling upon overrun
                 * condition: the controller may sometimes be totally confused
                 * and refuse any new frame while its buffer is empty. The only
                 * way to re-sync the read vs. write buffer offsets is to
                 * stop any current handling and perform a reset.
                 */
                if (priv->flags & SJA1000_QUIRK_RESET_ON_OVERRUN)
                        ret = IRQ_WAKE_THREAD;
        }
        if (state != CAN_STATE_BUS_OFF && skb) {
                cf->can_id |= CAN_ERR_CNT;
                cf->data[6] = bec.txerr;
                cf->data[7] = bec.rxerr;
        }
        if (isrc & IRQ_BEI) {
                /* bus error interrupt */
                priv->can.can_stats.bus_error++;

                ecc = priv->read_reg(priv, SJA1000_ECC);
                if (skb) {
                        cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;

                        /* set error type */
                        switch (ecc & ECC_MASK) {
                        case ECC_BIT:
                                cf->data[2] |= CAN_ERR_PROT_BIT;
                                break;
                        case ECC_FORM:
                                cf->data[2] |= CAN_ERR_PROT_FORM;
                                break;
                        case ECC_STUFF:
                                cf->data[2] |= CAN_ERR_PROT_STUFF;
                                break;
                        default:
                                break;
                        }

                        /* set error location */
                        cf->data[3] = ecc & ECC_SEG;
                }

                /* Error occurred during transmission? */
                if ((ecc & ECC_DIR) == 0) {
                        stats->tx_errors++;
                        if (skb)
                                cf->data[2] |= CAN_ERR_PROT_TX;
                } else {
                        stats->rx_errors++;
                }
        }
        if (isrc & IRQ_ALI) {
                /* arbitration lost interrupt */
                netdev_dbg(dev, "arbitration lost interrupt\n");
                alc = priv->read_reg(priv, SJA1000_ALC);
                priv->can.can_stats.arbitration_lost++;
                if (skb) {
                        cf->can_id |= CAN_ERR_LOSTARB;
                        cf->data[0] = alc & 0x1f;
                }
        }

        if (state != priv->can.state) {
                can_change_state(dev, cf, tx_state, rx_state);

                if(state == CAN_STATE_BUS_OFF)
                        can_bus_off(dev);
        }

        if (!skb)
                return -ENOMEM;

        netif_rx(skb);

        return ret;
}

irqreturn_t sja1000_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = (struct net_device *)dev_id;
        struct sja1000_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        uint8_t isrc, status;
        irqreturn_t ret = 0;
        int n = 0, err;

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

        /* Shared interrupts and IRQ off? */
        if (priv->read_reg(priv, SJA1000_IER) == IRQ_OFF)
                goto out;

        while ((n < SJA1000_MAX_IRQ) &&
               (isrc = priv->read_reg(priv, SJA1000_IR))) {

                status = priv->read_reg(priv, SJA1000_SR);
                /* check for absent controller due to hw unplug */
                if (status == 0xFF && sja1000_is_absent(priv))
                        goto out;

                if (isrc & IRQ_WUI)
                        netdev_warn(dev, "wakeup interrupt\n");

                if (isrc & IRQ_TI) {
                        /* transmission buffer released */
                        if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT &&
                            !(status & SR_TCS)) {
                                stats->tx_errors++;
                                can_free_echo_skb(dev, 0, NULL);
                        } else {
                                /* transmission complete */
                                stats->tx_bytes += can_get_echo_skb(dev, 0, NULL);
                                stats->tx_packets++;
                        }
                        netif_wake_queue(dev);
                }
                if (isrc & IRQ_RI) {
                        /* receive interrupt */
                        while (status & SR_RBS) {
                                sja1000_rx(dev);
                                status = priv->read_reg(priv, SJA1000_SR);
                                /* check for absent controller */
                                if (status == 0xFF && sja1000_is_absent(priv))
                                        goto out;
                        }
                }
                if (isrc & (IRQ_DOI | IRQ_EI | IRQ_BEI | IRQ_EPI | IRQ_ALI)) {
                        /* error interrupt */
                        err = sja1000_err(dev, isrc, status);
                        if (err == IRQ_WAKE_THREAD)
                                ret = err;
                        if (err)
                                break;
                }
                n++;
        }
out:
        if (!ret)
                ret = (n) ? IRQ_HANDLED : IRQ_NONE;

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

        if (n >= SJA1000_MAX_IRQ)
                netdev_dbg(dev, "%d messages handled in ISR", n);

        return ret;
}
EXPORT_SYMBOL_GPL(sja1000_interrupt);

static int sja1000_open(struct net_device *dev)
{
        struct sja1000_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;

        /* register interrupt handler, if not done by the device driver */
        if (!(priv->flags & SJA1000_CUSTOM_IRQ_HANDLER)) {
                err = request_threaded_irq(dev->irq, sja1000_interrupt,
                                           sja1000_reset_interrupt,
                                           priv->irq_flags, dev->name, (void *)dev);
                if (err) {
                        close_candev(dev);
                        return -EAGAIN;
                }
        }

        /* init and start chi */
        sja1000_start(dev);

        netif_start_queue(dev);

        return 0;
}

static int sja1000_close(struct net_device *dev)
{
        struct sja1000_priv *priv = netdev_priv(dev);

        netif_stop_queue(dev);
        set_reset_mode(dev);

        if (!(priv->flags & SJA1000_CUSTOM_IRQ_HANDLER))
                free_irq(dev->irq, (void *)dev);

        close_candev(dev);

        return 0;
}

struct net_device *alloc_sja1000dev(int sizeof_priv)
{
        struct net_device *dev;
        struct sja1000_priv *priv;

        dev = alloc_candev(sizeof(struct sja1000_priv) + sizeof_priv,
                SJA1000_ECHO_SKB_MAX);
        if (!dev)
                return NULL;

        priv = netdev_priv(dev);

        priv->dev = dev;
        priv->can.bittiming_const = &sja1000_bittiming_const;
        priv->can.do_set_bittiming = sja1000_set_bittiming;
        priv->can.do_set_mode = sja1000_set_mode;
        priv->can.do_get_berr_counter = sja1000_get_berr_counter;
        priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
                                       CAN_CTRLMODE_LISTENONLY |
                                       CAN_CTRLMODE_3_SAMPLES |
                                       CAN_CTRLMODE_ONE_SHOT |
                                       CAN_CTRLMODE_BERR_REPORTING |
                                       CAN_CTRLMODE_PRESUME_ACK |
                                       CAN_CTRLMODE_CC_LEN8_DLC;

        spin_lock_init(&priv->cmdreg_lock);

        if (sizeof_priv)
                priv->priv = (void *)priv + sizeof(struct sja1000_priv);

        return dev;
}
EXPORT_SYMBOL_GPL(alloc_sja1000dev);

void free_sja1000dev(struct net_device *dev)
{
        free_candev(dev);
}
EXPORT_SYMBOL_GPL(free_sja1000dev);

static const struct net_device_ops sja1000_netdev_ops = {
        .ndo_open       = sja1000_open,
        .ndo_stop       = sja1000_close,
        .ndo_start_xmit = sja1000_start_xmit,
};

static const struct ethtool_ops sja1000_ethtool_ops = {
        .get_ts_info = ethtool_op_get_ts_info,
};

int register_sja1000dev(struct net_device *dev)
{
        if (!sja1000_probe_chip(dev))
                return -ENODEV;

        dev->flags |= IFF_ECHO; /* we support local echo */
        dev->netdev_ops = &sja1000_netdev_ops;
        dev->ethtool_ops = &sja1000_ethtool_ops;

        set_reset_mode(dev);
        chipset_init(dev);

        return register_candev(dev);
}
EXPORT_SYMBOL_GPL(register_sja1000dev);

void unregister_sja1000dev(struct net_device *dev)
{
        set_reset_mode(dev);
        unregister_candev(dev);
}
EXPORT_SYMBOL_GPL(unregister_sja1000dev);