/*
 * 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/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, REG_CMR, val);
        priv->read_reg(priv, REG_SR);
        spin_unlock_irqrestore(&priv->cmdreg_lock, flags);
}

static int sja1000_is_absent(struct sja1000_priv *priv)
{
        return (priv->read_reg(priv, REG_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)) {
                printk(KERN_INFO "%s: probing @0x%lX failed\n",
                       DRV_NAME, dev->base_addr);
                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, REG_MOD);
        int i;

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

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

                priv->write_reg(priv, REG_MOD, MOD_RM); /* reset chip */
                udelay(10);
                status = priv->read_reg(priv, REG_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, REG_MOD);
        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, REG_IER, IRQ_ALL);
                        else
                                priv->write_reg(priv, REG_IER,
                                                IRQ_ALL & ~IRQ_BEI);
                        return;
                }

                /* set chip to normal mode */
                priv->write_reg(priv, REG_MOD, 0x00);
                udelay(10);
                status = priv->read_reg(priv, REG_MOD);
        }

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

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

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

        /* Clear error counters and error code capture */
        priv->write_reg(priv, REG_TXERR, 0x0);
        priv->write_reg(priv, REG_RXERR, 0x0);
        priv->read_reg(priv, REG_ECC);

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

static int sja1000_set_mode(struct net_device *dev, enum can_mode mode)
{
        struct sja1000_priv *priv = netdev_priv(dev);

        if (!priv->open_time)
                return -EINVAL;

        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, REG_BTR0, btr0);
        priv->write_reg(priv, REG_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, REG_TXERR);
        bec->rxerr = priv->read_reg(priv, REG_RXERR);

        return 0;
}

/*
 * 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);

        /* set clock divider and output control register */
        priv->write_reg(priv, REG_CDR, priv->cdr | CDR_PELICAN);

        /* set acceptance filter (accept all) */
        priv->write_reg(priv, REG_ACCC0, 0x00);
        priv->write_reg(priv, REG_ACCC1, 0x00);
        priv->write_reg(priv, REG_ACCC2, 0x00);
        priv->write_reg(priv, REG_ACCC3, 0x00);

        priv->write_reg(priv, REG_ACCM0, 0xFF);
        priv->write_reg(priv, REG_ACCM1, 0xFF);
        priv->write_reg(priv, REG_ACCM2, 0xFF);
        priv->write_reg(priv, REG_ACCM3, 0xFF);

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

/*
 * 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;
        uint8_t dlc;
        canid_t id;
        uint8_t dreg;
        int i;

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

        netif_stop_queue(dev);

        fi = dlc = cf->can_dlc;
        id = cf->can_id;

        if (id & CAN_RTR_FLAG)
                fi |= FI_RTR;

        if (id & CAN_EFF_FLAG) {
                fi |= FI_FF;
                dreg = EFF_BUF;
                priv->write_reg(priv, REG_FI, fi);
                priv->write_reg(priv, REG_ID1, (id & 0x1fe00000) >> (5 + 16));
                priv->write_reg(priv, REG_ID2, (id & 0x001fe000) >> (5 + 8));
                priv->write_reg(priv, REG_ID3, (id & 0x00001fe0) >> 5);
                priv->write_reg(priv, REG_ID4, (id & 0x0000001f) << 3);
        } else {
                dreg = SFF_BUF;
                priv->write_reg(priv, REG_FI, fi);
                priv->write_reg(priv, REG_ID1, (id & 0x000007f8) >> 3);
                priv->write_reg(priv, REG_ID2, (id & 0x00000007) << 5);
        }

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

        can_put_echo_skb(skb, dev, 0);

        sja1000_write_cmdreg(priv, CMD_TR);

        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, REG_FI);

        if (fi & FI_FF) {
                /* extended frame format (EFF) */
                dreg = EFF_BUF;
                id = (priv->read_reg(priv, REG_ID1) << (5 + 16))
                    | (priv->read_reg(priv, REG_ID2) << (5 + 8))
                    | (priv->read_reg(priv, REG_ID3) << 5)
                    | (priv->read_reg(priv, REG_ID4) >> 3);
                id |= CAN_EFF_FLAG;
        } else {
                /* standard frame format (SFF) */
                dreg = SFF_BUF;
                id = (priv->read_reg(priv, REG_ID1) << 3)
                    | (priv->read_reg(priv, REG_ID2) >> 5);
        }

        cf->can_dlc = get_can_dlc(fi & 0x0F);
        if (fi & FI_RTR) {
                id |= CAN_RTR_FLAG;
        } else {
                for (i = 0; i < cf->can_dlc; i++)
                        cf->data[i] = priv->read_reg(priv, dreg++);
        }

        cf->can_id = id;

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

        netif_rx(skb);

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

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;
        struct can_frame *cf;
        struct sk_buff *skb;
        enum can_state state = priv->can.state;
        uint8_t ecc, alc;

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

        if (isrc & IRQ_DOI) {
                /* data overrun interrupt */
                netdev_dbg(dev, "data overrun interrupt\n");
                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 */
        }

        if (isrc & IRQ_EI) {
                /* error warning interrupt */
                netdev_dbg(dev, "error warning interrupt\n");

                if (status & SR_BS) {
                        state = CAN_STATE_BUS_OFF;
                        cf->can_id |= CAN_ERR_BUSOFF;
                        can_bus_off(dev);
                } else if (status & SR_ES) {
                        state = CAN_STATE_ERROR_WARNING;
                } else
                        state = CAN_STATE_ERROR_ACTIVE;
        }
        if (isrc & IRQ_BEI) {
                /* bus error interrupt */
                priv->can.can_stats.bus_error++;
                stats->rx_errors++;

                ecc = priv->read_reg(priv, REG_ECC);

                cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;

                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:
                        cf->data[2] |= CAN_ERR_PROT_UNSPEC;
                        cf->data[3] = ecc & ECC_SEG;
                        break;
                }
                /* Error occurred during transmission? */
                if ((ecc & ECC_DIR) == 0)
                        cf->data[2] |= CAN_ERR_PROT_TX;
        }
        if (isrc & IRQ_EPI) {
                /* error passive interrupt */
                netdev_dbg(dev, "error passive interrupt\n");
                if (status & SR_ES)
                        state = CAN_STATE_ERROR_PASSIVE;
                else
                        state = CAN_STATE_ERROR_ACTIVE;
        }
        if (isrc & IRQ_ALI) {
                /* arbitration lost interrupt */
                netdev_dbg(dev, "arbitration lost interrupt\n");
                alc = priv->read_reg(priv, REG_ALC);
                priv->can.can_stats.arbitration_lost++;
                stats->tx_errors++;
                cf->can_id |= CAN_ERR_LOSTARB;
                cf->data[0] = alc & 0x1f;
        }

        if (state != priv->can.state && (state == CAN_STATE_ERROR_WARNING ||
                                         state == CAN_STATE_ERROR_PASSIVE)) {
                uint8_t rxerr = priv->read_reg(priv, REG_RXERR);
                uint8_t txerr = priv->read_reg(priv, REG_TXERR);
                cf->can_id |= CAN_ERR_CRTL;
                if (state == CAN_STATE_ERROR_WARNING) {
                        priv->can.can_stats.error_warning++;
                        cf->data[1] = (txerr > rxerr) ?
                                CAN_ERR_CRTL_TX_WARNING :
                                CAN_ERR_CRTL_RX_WARNING;
                } else {
                        priv->can.can_stats.error_passive++;
                        cf->data[1] = (txerr > rxerr) ?
                                CAN_ERR_CRTL_TX_PASSIVE :
                                CAN_ERR_CRTL_RX_PASSIVE;
                }
                cf->data[6] = txerr;
                cf->data[7] = rxerr;
        }

        priv->can.state = state;

        netif_rx(skb);

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

        return 0;
}

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;
        int n = 0;

        /* Shared interrupts and IRQ off? */
        if (priv->read_reg(priv, REG_IER) == IRQ_OFF)
                return IRQ_NONE;

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

        while ((isrc = priv->read_reg(priv, REG_IR)) && (n < SJA1000_MAX_IRQ)) {
                n++;
                status = priv->read_reg(priv, REG_SR);
                /* check for absent controller due to hw unplug */
                if (status == 0xFF && sja1000_is_absent(priv))
                        return IRQ_NONE;

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

                if (isrc & IRQ_TI) {
                        /* transmission complete interrupt */
                        stats->tx_bytes += priv->read_reg(priv, REG_FI) & 0xf;
                        stats->tx_packets++;
                        can_get_echo_skb(dev, 0);
                        netif_wake_queue(dev);
                }
                if (isrc & IRQ_RI) {
                        /* receive interrupt */
                        while (status & SR_RBS) {
                                sja1000_rx(dev);
                                status = priv->read_reg(priv, REG_SR);
                                /* check for absent controller */
                                if (status == 0xFF && sja1000_is_absent(priv))
                                        return IRQ_NONE;
                        }
                }
                if (isrc & (IRQ_DOI | IRQ_EI | IRQ_BEI | IRQ_EPI | IRQ_ALI)) {
                        /* error interrupt */
                        if (sja1000_err(dev, isrc, status))
                                break;
                }
        }

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

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

        return (n) ? IRQ_HANDLED : IRQ_NONE;
}
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_irq(dev->irq, sja1000_interrupt, priv->irq_flags,
                                  dev->name, (void *)dev);
                if (err) {
                        close_candev(dev);
                        return -EAGAIN;
                }
        }

        /* init and start chi */
        sja1000_start(dev);
        priv->open_time = jiffies;

        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);

        priv->open_time = 0;

        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_3_SAMPLES |
                CAN_CTRLMODE_BERR_REPORTING;

        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,
};

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;

        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);

static __init int sja1000_init(void)
{
        printk(KERN_INFO "%s CAN netdevice driver\n", DRV_NAME);

        return 0;
}

module_init(sja1000_init);

static __exit void sja1000_exit(void)
{
        printk(KERN_INFO "%s: driver removed\n", DRV_NAME);
}

module_exit(sja1000_exit);