drivers/net/can/mscan/mscan.c - kernel/msm-4.9 - Gitiles

 /*
  * CAN bus driver for the alone generic (as possible as) MSCAN controller.
  *
  * Copyright (C) 2005-2006 Andrey Volkov <avolkov@varma-el.com>,
  *                         Varma Electronics Oy
  * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
  * Copytight (C) 2008-2009 Pengutronix <kernel@pengutronix.de>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the version 2 of the GNU General Public License
  * as published by the Free Software Foundation
  *
  * 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, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/netdevice.h>
 #include <linux/if_arp.h>
 #include <linux/if_ether.h>
 #include <linux/list.h>
 #include <linux/can.h>
 #include <linux/can/dev.h>
 #include <linux/can/error.h>
 #include <linux/io.h>

 #include "mscan.h"

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

 struct mscan_state {
 	u8 mode;
 	u8 canrier;
 	u8 cantier;
 };

 static enum can_state state_map[] = {
 	CAN_STATE_ERROR_ACTIVE,
 	CAN_STATE_ERROR_WARNING,
 	CAN_STATE_ERROR_PASSIVE,
 	CAN_STATE_BUS_OFF
 };

 static int mscan_set_mode(struct net_device *dev, u8 mode)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	int ret = 0;
 	int i;
 	u8 canctl1;

 	if (mode != MSCAN_NORMAL_MODE) {
 		if (priv->tx_active) {
 			/* Abort transfers before going to sleep */#
 			out_8(&regs->cantarq, priv->tx_active);
 			/* Suppress TX done interrupts */
 			out_8(&regs->cantier, 0);
 		}

 		canctl1 = in_8(&regs->canctl1);
 		if ((mode & MSCAN_SLPRQ) && !(canctl1 & MSCAN_SLPAK)) {
 			setbits8(&regs->canctl0, MSCAN_SLPRQ);
 			for (i = 0; i < MSCAN_SET_MODE_RETRIES; i++) {
 				if (in_8(&regs->canctl1) & MSCAN_SLPAK)
 					break;
 				udelay(100);
 			}
 			/*
 			 * The mscan controller will fail to enter sleep mode,
 			 * while there are irregular activities on bus, like
 			 * somebody keeps retransmitting. This behavior is
 			 * undocumented and seems to differ between mscan built
 			 * in mpc5200b and mpc5200. We proceed in that case,
 			 * since otherwise the slprq will be kept set and the
 			 * controller will get stuck. NOTE: INITRQ or CSWAI
 			 * will abort all active transmit actions, if still
 			 * any, at once.
 			 */
 			if (i >= MSCAN_SET_MODE_RETRIES)
 				dev_dbg(dev->dev.parent,
 					"device failed to enter sleep mode. "
 					"We proceed anyhow.\n");
 			else
 				priv->can.state = CAN_STATE_SLEEPING;
 		}

 		if ((mode & MSCAN_INITRQ) && !(canctl1 & MSCAN_INITAK)) {
 			setbits8(&regs->canctl0, MSCAN_INITRQ);
 			for (i = 0; i < MSCAN_SET_MODE_RETRIES; i++) {
 				if (in_8(&regs->canctl1) & MSCAN_INITAK)
 					break;
 			}
 			if (i >= MSCAN_SET_MODE_RETRIES)
 				ret = -ENODEV;
 		}
 		if (!ret)
 			priv->can.state = CAN_STATE_STOPPED;

 		if (mode & MSCAN_CSWAI)
 			setbits8(&regs->canctl0, MSCAN_CSWAI);

 	} else {
 		canctl1 = in_8(&regs->canctl1);
 		if (canctl1 & (MSCAN_SLPAK | MSCAN_INITAK)) {
 			clrbits8(&regs->canctl0, MSCAN_SLPRQ | MSCAN_INITRQ);
 			for (i = 0; i < MSCAN_SET_MODE_RETRIES; i++) {
 				canctl1 = in_8(&regs->canctl1);
 				if (!(canctl1 & (MSCAN_INITAK | MSCAN_SLPAK)))
 					break;
 			}
 			if (i >= MSCAN_SET_MODE_RETRIES)
 				ret = -ENODEV;
 			else
 				priv->can.state = CAN_STATE_ERROR_ACTIVE;
 		}
 	}
 	return ret;
 }

 static int mscan_start(struct net_device *dev)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	u8 canrflg;
 	int err;

 	out_8(&regs->canrier, 0);

 	INIT_LIST_HEAD(&priv->tx_head);
 	priv->prev_buf_id = 0;
 	priv->cur_pri = 0;
 	priv->tx_active = 0;
 	priv->shadow_canrier = 0;
 	priv->flags = 0;

 	err = mscan_set_mode(dev, MSCAN_NORMAL_MODE);
 	if (err)
 		return err;

 	canrflg = in_8(&regs->canrflg);
 	priv->shadow_statflg = canrflg & MSCAN_STAT_MSK;
 	priv->can.state = state_map[max(MSCAN_STATE_RX(canrflg),
 				    MSCAN_STATE_TX(canrflg))];
 	out_8(&regs->cantier, 0);

 	/* Enable receive interrupts. */
 	out_8(&regs->canrier, MSCAN_OVRIE | MSCAN_RXFIE | MSCAN_CSCIE |
 	      MSCAN_RSTATE1 | MSCAN_RSTATE0 | MSCAN_TSTATE1 | MSCAN_TSTATE0);

 	return 0;
 }

 static netdev_tx_t mscan_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct can_frame *frame = (struct can_frame *)skb->data;
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	int i, rtr, buf_id;
 	u32 can_id;

 	if (frame->can_dlc > 8)
 		return -EINVAL;

 	out_8(&regs->cantier, 0);

 	i = ~priv->tx_active & MSCAN_TXE;
 	buf_id = ffs(i) - 1;
 	switch (hweight8(i)) {
 	case 0:
 		netif_stop_queue(dev);
 		dev_err(dev->dev.parent, "Tx Ring full when queue awake!\n");
 		return NETDEV_TX_BUSY;
 	case 1:
 		/*
 		 * if buf_id < 3, then current frame will be send out of order,
 		 * since buffer with lower id have higher priority (hell..)
 		 */
 		netif_stop_queue(dev);
 	case 2:
 		if (buf_id < priv->prev_buf_id) {
 			priv->cur_pri++;
 			if (priv->cur_pri == 0xff) {
 				set_bit(F_TX_WAIT_ALL, &priv->flags);
 				netif_stop_queue(dev);
 			}
 		}
 		set_bit(F_TX_PROGRESS, &priv->flags);
 		break;
 	}
 	priv->prev_buf_id = buf_id;
 	out_8(&regs->cantbsel, i);

 	rtr = frame->can_id & CAN_RTR_FLAG;

 	if (frame->can_id & CAN_EFF_FLAG) {
 		can_id = (frame->can_id & CAN_EFF_MASK) << 1;
 		if (rtr)
 			can_id |= 1;
 		out_be16(&regs->tx.idr3_2, can_id);

 		can_id >>= 16;
 		can_id = (can_id & 0x7) | ((can_id << 2) & 0xffe0) | (3 << 3);
 	} else {
 		can_id = (frame->can_id & CAN_SFF_MASK) << 5;
 		if (rtr)
 			can_id |= 1 << 4;
 	}
 	out_be16(&regs->tx.idr1_0, can_id);

 	if (!rtr) {
 		void __iomem *data = &regs->tx.dsr1_0;
 		u16 *payload = (u16 *)frame->data;

 		/* It is safe to write into dsr[dlc+1] */
 		for (i = 0; i < (frame->can_dlc + 1) / 2; i++) {
 			out_be16(data, *payload++);
 			data += 2 + _MSCAN_RESERVED_DSR_SIZE;
 		}
 	}

 	out_8(&regs->tx.dlr, frame->can_dlc);
 	out_8(&regs->tx.tbpr, priv->cur_pri);

 	/* Start transmission. */
 	out_8(&regs->cantflg, 1 << buf_id);

 	if (!test_bit(F_TX_PROGRESS, &priv->flags))
 		dev->trans_start = jiffies;

 	list_add_tail(&priv->tx_queue[buf_id].list, &priv->tx_head);

 	can_put_echo_skb(skb, dev, buf_id);

 	/* Enable interrupt. */
 	priv->tx_active |= 1 << buf_id;
 	out_8(&regs->cantier, priv->tx_active);

 	return NETDEV_TX_OK;
 }

 /* This function returns the old state to see where we came from */
 static enum can_state check_set_state(struct net_device *dev, u8 canrflg)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	enum can_state state, old_state = priv->can.state;

 	if (canrflg & MSCAN_CSCIF && old_state <= CAN_STATE_BUS_OFF) {
 		state = state_map[max(MSCAN_STATE_RX(canrflg),
 				      MSCAN_STATE_TX(canrflg))];
 		priv->can.state = state;
 	}
 	return old_state;
 }

 static void mscan_get_rx_frame(struct net_device *dev, struct can_frame *frame)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	u32 can_id;
 	int i;

 	can_id = in_be16(&regs->rx.idr1_0);
 	if (can_id & (1 << 3)) {
 		frame->can_id = CAN_EFF_FLAG;
 		can_id = ((can_id << 16) | in_be16(&regs->rx.idr3_2));
 		can_id = ((can_id & 0xffe00000) |
 			  ((can_id & 0x7ffff) << 2)) >> 2;
 	} else {
 		can_id >>= 4;
 		frame->can_id = 0;
 	}

 	frame->can_id |= can_id >> 1;
 	if (can_id & 1)
 		frame->can_id |= CAN_RTR_FLAG;
 	frame->can_dlc = in_8(&regs->rx.dlr) & 0xf;

 	if (!(frame->can_id & CAN_RTR_FLAG)) {
 		void __iomem *data = &regs->rx.dsr1_0;
 		u16 *payload = (u16 *)frame->data;

 		for (i = 0; i < (frame->can_dlc + 1) / 2; i++) {
 			*payload++ = in_be16(data);
 			data += 2 + _MSCAN_RESERVED_DSR_SIZE;
 		}
 	}

 	out_8(&regs->canrflg, MSCAN_RXF);
 }

 static void mscan_get_err_frame(struct net_device *dev, struct can_frame *frame,
 				u8 canrflg)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	struct net_device_stats *stats = &dev->stats;
 	enum can_state old_state;

 	dev_dbg(dev->dev.parent, "error interrupt (canrflg=%#x)\n", canrflg);
 	frame->can_id = CAN_ERR_FLAG;

 	if (canrflg & MSCAN_OVRIF) {
 		frame->can_id |= CAN_ERR_CRTL;
 		frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
 		stats->rx_over_errors++;
 		stats->rx_errors++;
 	} else {
 		frame->data[1] = 0;
 	}

 	old_state = check_set_state(dev, canrflg);
 	/* State changed */
 	if (old_state != priv->can.state) {
 		switch (priv->can.state) {
 		case CAN_STATE_ERROR_WARNING:
 			frame->can_id |= CAN_ERR_CRTL;
 			priv->can.can_stats.error_warning++;
 			if ((priv->shadow_statflg & MSCAN_RSTAT_MSK) <
 			    (canrflg & MSCAN_RSTAT_MSK))
 				frame->data[1] |= CAN_ERR_CRTL_RX_WARNING;
 			if ((priv->shadow_statflg & MSCAN_TSTAT_MSK) <
 			    (canrflg & MSCAN_TSTAT_MSK))
 				frame->data[1] |= CAN_ERR_CRTL_TX_WARNING;
 			break;
 		case CAN_STATE_ERROR_PASSIVE:
 			frame->can_id |= CAN_ERR_CRTL;
 			priv->can.can_stats.error_passive++;
 			frame->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
 			break;
 		case CAN_STATE_BUS_OFF:
 			frame->can_id |= CAN_ERR_BUSOFF;
 			/*
 			 * The MSCAN on the MPC5200 does recover from bus-off
 			 * automatically. To avoid that we stop the chip doing
 			 * a light-weight stop (we are in irq-context).
 			 */
 			out_8(&regs->cantier, 0);
 			out_8(&regs->canrier, 0);
 			setbits8(&regs->canctl0, MSCAN_SLPRQ | MSCAN_INITRQ);
 			can_bus_off(dev);
 			break;
 		default:
 			break;
 		}
 	}
 	priv->shadow_statflg = canrflg & MSCAN_STAT_MSK;
 	frame->can_dlc = CAN_ERR_DLC;
 	out_8(&regs->canrflg, MSCAN_ERR_IF);
 }

 static int mscan_rx_poll(struct napi_struct *napi, int quota)
 {
 	struct mscan_priv *priv = container_of(napi, struct mscan_priv, napi);
 	struct net_device *dev = napi->dev;
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	struct net_device_stats *stats = &dev->stats;
 	int npackets = 0;
 	int ret = 1;
 	struct sk_buff *skb;
 	struct can_frame *frame;
 	u8 canrflg;

 	while (npackets < quota && ((canrflg = in_8(&regs->canrflg)) &
 				    (MSCAN_RXF | MSCAN_ERR_IF))) {

 		skb = alloc_can_skb(dev, &frame);
 		if (!skb) {
 			if (printk_ratelimit())
 				dev_notice(dev->dev.parent, "packet dropped\n");
 			stats->rx_dropped++;
 			out_8(&regs->canrflg, canrflg);
 			continue;
 		}

 		if (canrflg & MSCAN_RXF)
 			mscan_get_rx_frame(dev, frame);
 		else if (canrflg & MSCAN_ERR_IF)
 			mscan_get_err_frame(dev, frame, canrflg);

 		stats->rx_packets++;
 		stats->rx_bytes += frame->can_dlc;
 		npackets++;
 		netif_receive_skb(skb);
 	}

 	if (!(in_8(&regs->canrflg) & (MSCAN_RXF | MSCAN_ERR_IF))) {
 		napi_complete(&priv->napi);
 		clear_bit(F_RX_PROGRESS, &priv->flags);
 		if (priv->can.state < CAN_STATE_BUS_OFF)
 			out_8(&regs->canrier, priv->shadow_canrier);
 		ret = 0;
 	}
 	return ret;
 }

 static irqreturn_t mscan_isr(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *)dev_id;
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	struct net_device_stats *stats = &dev->stats;
 	u8 cantier, cantflg, canrflg;
 	irqreturn_t ret = IRQ_NONE;

 	cantier = in_8(&regs->cantier) & MSCAN_TXE;
 	cantflg = in_8(&regs->cantflg) & cantier;

 	if (cantier && cantflg) {
 		struct list_head *tmp, *pos;

 		list_for_each_safe(pos, tmp, &priv->tx_head) {
 			struct tx_queue_entry *entry =
 			    list_entry(pos, struct tx_queue_entry, list);
 			u8 mask = entry->mask;

 			if (!(cantflg & mask))
 				continue;

 			out_8(&regs->cantbsel, mask);
 			stats->tx_bytes += in_8(&regs->tx.dlr);
 			stats->tx_packets++;
 			can_get_echo_skb(dev, entry->id);
 			priv->tx_active &= ~mask;
 			list_del(pos);
 		}

 		if (list_empty(&priv->tx_head)) {
 			clear_bit(F_TX_WAIT_ALL, &priv->flags);
 			clear_bit(F_TX_PROGRESS, &priv->flags);
 			priv->cur_pri = 0;
 		} else {
 			dev->trans_start = jiffies;
 		}

 		if (!test_bit(F_TX_WAIT_ALL, &priv->flags))
 			netif_wake_queue(dev);

 		out_8(&regs->cantier, priv->tx_active);
 		ret = IRQ_HANDLED;
 	}

 	canrflg = in_8(&regs->canrflg);
 	if ((canrflg & ~MSCAN_STAT_MSK) &&
 	    !test_and_set_bit(F_RX_PROGRESS, &priv->flags)) {
 		if (canrflg & ~MSCAN_STAT_MSK) {
 			priv->shadow_canrier = in_8(&regs->canrier);
 			out_8(&regs->canrier, 0);
 			napi_schedule(&priv->napi);
 			ret = IRQ_HANDLED;
 		} else {
 			clear_bit(F_RX_PROGRESS, &priv->flags);
 		}
 	}
 	return ret;
 }

 static int mscan_do_set_mode(struct net_device *dev, enum can_mode mode)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	int ret = 0;

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

 	switch (mode) {
 	case CAN_MODE_START:
 		if (priv->can.state <= CAN_STATE_BUS_OFF)
 			mscan_set_mode(dev, MSCAN_INIT_MODE);
 		ret = mscan_start(dev);
 		if (ret)
 			break;
 		if (netif_queue_stopped(dev))
 			netif_wake_queue(dev);
 		break;

 	default:
 		ret = -EOPNOTSUPP;
 		break;
 	}
 	return ret;
 }

 static int mscan_do_set_bittiming(struct net_device *dev)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	struct can_bittiming *bt = &priv->can.bittiming;
 	u8 btr0, btr1;

 	btr0 = BTR0_SET_BRP(bt->brp) | BTR0_SET_SJW(bt->sjw);
 	btr1 = (BTR1_SET_TSEG1(bt->prop_seg + bt->phase_seg1) |
 		BTR1_SET_TSEG2(bt->phase_seg2) |
 		BTR1_SET_SAM(priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES));

 	dev_info(dev->dev.parent, "setting BTR0=0x%02x BTR1=0x%02x\n",
 		btr0, btr1);

 	out_8(&regs->canbtr0, btr0);
 	out_8(&regs->canbtr1, btr1);

 	return 0;
 }

 static int mscan_open(struct net_device *dev)
 {
 	int ret;
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;

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

 	napi_enable(&priv->napi);

 	ret = request_irq(dev->irq, mscan_isr, 0, dev->name, dev);
 	if (ret < 0) {
 		napi_disable(&priv->napi);
 		printk(KERN_ERR "%s - failed to attach interrupt\n",
 		       dev->name);
 		return ret;
 	}

 	priv->open_time = jiffies;

 	clrbits8(&regs->canctl1, MSCAN_LISTEN);

 	ret = mscan_start(dev);
 	if (ret)
 		return ret;

 	netif_start_queue(dev);

 	return 0;
 }

 static int mscan_close(struct net_device *dev)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;

 	netif_stop_queue(dev);
 	napi_disable(&priv->napi);

 	out_8(&regs->cantier, 0);
 	out_8(&regs->canrier, 0);
 	mscan_set_mode(dev, MSCAN_INIT_MODE);
 	close_candev(dev);
 	free_irq(dev->irq, dev);
 	priv->open_time = 0;

 	return 0;
 }

 static const struct net_device_ops mscan_netdev_ops = {
        .ndo_open               = mscan_open,
        .ndo_stop               = mscan_close,
        .ndo_start_xmit         = mscan_start_xmit,
 };

 int register_mscandev(struct net_device *dev, int clock_src)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	u8 ctl1;

 	ctl1 = in_8(&regs->canctl1);
 	if (clock_src)
 		ctl1 |= MSCAN_CLKSRC;
 	else
 		ctl1 &= ~MSCAN_CLKSRC;

 	ctl1 |= MSCAN_CANE;
 	out_8(&regs->canctl1, ctl1);
 	udelay(100);

 	/* acceptance mask/acceptance code (accept everything) */
 	out_be16(&regs->canidar1_0, 0);
 	out_be16(&regs->canidar3_2, 0);
 	out_be16(&regs->canidar5_4, 0);
 	out_be16(&regs->canidar7_6, 0);

 	out_be16(&regs->canidmr1_0, 0xffff);
 	out_be16(&regs->canidmr3_2, 0xffff);
 	out_be16(&regs->canidmr5_4, 0xffff);
 	out_be16(&regs->canidmr7_6, 0xffff);
 	/* Two 32 bit Acceptance Filters */
 	out_8(&regs->canidac, MSCAN_AF_32BIT);

 	mscan_set_mode(dev, MSCAN_INIT_MODE);

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

 void unregister_mscandev(struct net_device *dev)
 {
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;
 	mscan_set_mode(dev, MSCAN_INIT_MODE);
 	clrbits8(&regs->canctl1, MSCAN_CANE);
 	unregister_candev(dev);
 }
 EXPORT_SYMBOL_GPL(unregister_mscandev);

 struct net_device *alloc_mscandev(void)
 {
 	struct net_device *dev;
 	struct mscan_priv *priv;
 	int i;

 	dev = alloc_candev(sizeof(struct mscan_priv), MSCAN_ECHO_SKB_MAX);
 	if (!dev)
 		return NULL;
 	priv = netdev_priv(dev);

 	dev->netdev_ops = &mscan_netdev_ops;

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

 	netif_napi_add(dev, &priv->napi, mscan_rx_poll, 8);

 	priv->can.bittiming_const = &mscan_bittiming_const;
 	priv->can.do_set_bittiming = mscan_do_set_bittiming;
 	priv->can.do_set_mode = mscan_do_set_mode;

 	for (i = 0; i < TX_QUEUE_SIZE; i++) {
 		priv->tx_queue[i].id = i;
 		priv->tx_queue[i].mask = 1 << i;
 	}

 	return dev;
 }
 EXPORT_SYMBOL_GPL(alloc_mscandev);

 MODULE_AUTHOR("Andrey Volkov <avolkov@varma-el.com>");
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("CAN port driver for a MSCAN based chips");
	/*
	* CAN bus driver for the alone generic (as possible as) MSCAN controller.
	*
	* Copyright (C) 2005-2006 Andrey Volkov <avolkov@varma-el.com>,
	* Varma Electronics Oy
	* Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
	* Copytight (C) 2008-2009 Pengutronix <kernel@pengutronix.de>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the version 2 of the GNU General Public License
	* as published by the Free Software Foundation
	*
	* 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, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/delay.h>
	#include <linux/netdevice.h>
	#include <linux/if_arp.h>
	#include <linux/if_ether.h>
	#include <linux/list.h>
	#include <linux/can.h>
	#include <linux/can/dev.h>
	#include <linux/can/error.h>
	#include <linux/io.h>

	#include "mscan.h"

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

	struct mscan_state {
	u8 mode;
	u8 canrier;
	u8 cantier;
	};

	static enum can_state state_map[] = {
	CAN_STATE_ERROR_ACTIVE,
	CAN_STATE_ERROR_WARNING,
	CAN_STATE_ERROR_PASSIVE,
	CAN_STATE_BUS_OFF
	};

	static int mscan_set_mode(struct net_device *dev, u8 mode)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	int ret = 0;
	int i;
	u8 canctl1;

	if (mode != MSCAN_NORMAL_MODE) {
	if (priv->tx_active) {
	/* Abort transfers before going to sleep */#
	out_8(&regs->cantarq, priv->tx_active);
	/* Suppress TX done interrupts */
	out_8(&regs->cantier, 0);
	}

	canctl1 = in_8(&regs->canctl1);
	if ((mode & MSCAN_SLPRQ) && !(canctl1 & MSCAN_SLPAK)) {
	setbits8(&regs->canctl0, MSCAN_SLPRQ);
	for (i = 0; i < MSCAN_SET_MODE_RETRIES; i++) {
	if (in_8(&regs->canctl1) & MSCAN_SLPAK)
	break;
	udelay(100);
	}
	/*
	* The mscan controller will fail to enter sleep mode,
	* while there are irregular activities on bus, like
	* somebody keeps retransmitting. This behavior is
	* undocumented and seems to differ between mscan built
	* in mpc5200b and mpc5200. We proceed in that case,
	* since otherwise the slprq will be kept set and the
	* controller will get stuck. NOTE: INITRQ or CSWAI
	* will abort all active transmit actions, if still
	* any, at once.
	*/
	if (i >= MSCAN_SET_MODE_RETRIES)
	dev_dbg(dev->dev.parent,
	"device failed to enter sleep mode. "
	"We proceed anyhow.\n");
	else
	priv->can.state = CAN_STATE_SLEEPING;
	}

	if ((mode & MSCAN_INITRQ) && !(canctl1 & MSCAN_INITAK)) {
	setbits8(&regs->canctl0, MSCAN_INITRQ);
	for (i = 0; i < MSCAN_SET_MODE_RETRIES; i++) {
	if (in_8(&regs->canctl1) & MSCAN_INITAK)
	break;
	}
	if (i >= MSCAN_SET_MODE_RETRIES)
	ret = -ENODEV;
	}
	if (!ret)
	priv->can.state = CAN_STATE_STOPPED;

	if (mode & MSCAN_CSWAI)
	setbits8(&regs->canctl0, MSCAN_CSWAI);

	} else {
	canctl1 = in_8(&regs->canctl1);
	if (canctl1 & (MSCAN_SLPAK \| MSCAN_INITAK)) {
	clrbits8(&regs->canctl0, MSCAN_SLPRQ \| MSCAN_INITRQ);
	for (i = 0; i < MSCAN_SET_MODE_RETRIES; i++) {
	canctl1 = in_8(&regs->canctl1);
	if (!(canctl1 & (MSCAN_INITAK \| MSCAN_SLPAK)))
	break;
	}
	if (i >= MSCAN_SET_MODE_RETRIES)
	ret = -ENODEV;
	else
	priv->can.state = CAN_STATE_ERROR_ACTIVE;
	}
	}
	return ret;
	}

	static int mscan_start(struct net_device *dev)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	u8 canrflg;
	int err;

	out_8(&regs->canrier, 0);

	INIT_LIST_HEAD(&priv->tx_head);
	priv->prev_buf_id = 0;
	priv->cur_pri = 0;
	priv->tx_active = 0;
	priv->shadow_canrier = 0;
	priv->flags = 0;

	err = mscan_set_mode(dev, MSCAN_NORMAL_MODE);
	if (err)
	return err;

	canrflg = in_8(&regs->canrflg);
	priv->shadow_statflg = canrflg & MSCAN_STAT_MSK;
	priv->can.state = state_map[max(MSCAN_STATE_RX(canrflg),
	MSCAN_STATE_TX(canrflg))];
	out_8(&regs->cantier, 0);

	/* Enable receive interrupts. */
	out_8(&regs->canrier, MSCAN_OVRIE \| MSCAN_RXFIE \| MSCAN_CSCIE \|
	MSCAN_RSTATE1 \| MSCAN_RSTATE0 \| MSCAN_TSTATE1 \| MSCAN_TSTATE0);

	return 0;
	}

	static netdev_tx_t mscan_start_xmit(struct sk_buff skb, struct net_device dev)
	{
	struct can_frame frame = (struct can_frame )skb->data;
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	int i, rtr, buf_id;
	u32 can_id;

	if (frame->can_dlc > 8)
	return -EINVAL;

	out_8(&regs->cantier, 0);

	i = ~priv->tx_active & MSCAN_TXE;
	buf_id = ffs(i) - 1;
	switch (hweight8(i)) {
	case 0:
	netif_stop_queue(dev);
	dev_err(dev->dev.parent, "Tx Ring full when queue awake!\n");
	return NETDEV_TX_BUSY;
	case 1:
	/*
	* if buf_id < 3, then current frame will be send out of order,
	* since buffer with lower id have higher priority (hell..)
	*/
	netif_stop_queue(dev);
	case 2:
	if (buf_id < priv->prev_buf_id) {
	priv->cur_pri++;
	if (priv->cur_pri == 0xff) {
	set_bit(F_TX_WAIT_ALL, &priv->flags);
	netif_stop_queue(dev);
	}
	}
	set_bit(F_TX_PROGRESS, &priv->flags);
	break;
	}
	priv->prev_buf_id = buf_id;
	out_8(&regs->cantbsel, i);

	rtr = frame->can_id & CAN_RTR_FLAG;

	if (frame->can_id & CAN_EFF_FLAG) {
	can_id = (frame->can_id & CAN_EFF_MASK) << 1;
	if (rtr)
	can_id \|= 1;
	out_be16(&regs->tx.idr3_2, can_id);

	can_id >>= 16;
	can_id = (can_id & 0x7) \| ((can_id << 2) & 0xffe0) \| (3 << 3);
	} else {
	can_id = (frame->can_id & CAN_SFF_MASK) << 5;
	if (rtr)
	can_id \|= 1 << 4;
	}
	out_be16(&regs->tx.idr1_0, can_id);

	if (!rtr) {
	void __iomem *data = &regs->tx.dsr1_0;
	u16 payload = (u16 )frame->data;

	/* It is safe to write into dsr[dlc+1] */
	for (i = 0; i < (frame->can_dlc + 1) / 2; i++) {
	out_be16(data, *payload++);
	data += 2 + _MSCAN_RESERVED_DSR_SIZE;
	}
	}

	out_8(&regs->tx.dlr, frame->can_dlc);
	out_8(&regs->tx.tbpr, priv->cur_pri);

	/* Start transmission. */
	out_8(&regs->cantflg, 1 << buf_id);

	if (!test_bit(F_TX_PROGRESS, &priv->flags))
	dev->trans_start = jiffies;

	list_add_tail(&priv->tx_queue[buf_id].list, &priv->tx_head);

	can_put_echo_skb(skb, dev, buf_id);

	/* Enable interrupt. */
	priv->tx_active \|= 1 << buf_id;
	out_8(&regs->cantier, priv->tx_active);

	return NETDEV_TX_OK;
	}

	/* This function returns the old state to see where we came from */
	static enum can_state check_set_state(struct net_device *dev, u8 canrflg)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	enum can_state state, old_state = priv->can.state;

	if (canrflg & MSCAN_CSCIF && old_state <= CAN_STATE_BUS_OFF) {
	state = state_map[max(MSCAN_STATE_RX(canrflg),
	MSCAN_STATE_TX(canrflg))];
	priv->can.state = state;
	}
	return old_state;
	}

	static void mscan_get_rx_frame(struct net_device dev, struct can_frame frame)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	u32 can_id;
	int i;

	can_id = in_be16(&regs->rx.idr1_0);
	if (can_id & (1 << 3)) {
	frame->can_id = CAN_EFF_FLAG;
	can_id = ((can_id << 16) \| in_be16(&regs->rx.idr3_2));
	can_id = ((can_id & 0xffe00000) \|
	((can_id & 0x7ffff) << 2)) >> 2;
	} else {
	can_id >>= 4;
	frame->can_id = 0;
	}

	frame->can_id \|= can_id >> 1;
	if (can_id & 1)
	frame->can_id \|= CAN_RTR_FLAG;
	frame->can_dlc = in_8(&regs->rx.dlr) & 0xf;

	if (!(frame->can_id & CAN_RTR_FLAG)) {
	void __iomem *data = &regs->rx.dsr1_0;
	u16 payload = (u16 )frame->data;

	for (i = 0; i < (frame->can_dlc + 1) / 2; i++) {
	*payload++ = in_be16(data);
	data += 2 + _MSCAN_RESERVED_DSR_SIZE;
	}
	}

	out_8(&regs->canrflg, MSCAN_RXF);
	}

	static void mscan_get_err_frame(struct net_device dev, struct can_frame frame,
	u8 canrflg)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	struct net_device_stats *stats = &dev->stats;
	enum can_state old_state;

	dev_dbg(dev->dev.parent, "error interrupt (canrflg=%#x)\n", canrflg);
	frame->can_id = CAN_ERR_FLAG;

	if (canrflg & MSCAN_OVRIF) {
	frame->can_id \|= CAN_ERR_CRTL;
	frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
	stats->rx_over_errors++;
	stats->rx_errors++;
	} else {
	frame->data[1] = 0;
	}

	old_state = check_set_state(dev, canrflg);
	/* State changed */
	if (old_state != priv->can.state) {
	switch (priv->can.state) {
	case CAN_STATE_ERROR_WARNING:
	frame->can_id \|= CAN_ERR_CRTL;
	priv->can.can_stats.error_warning++;
	if ((priv->shadow_statflg & MSCAN_RSTAT_MSK) <
	(canrflg & MSCAN_RSTAT_MSK))
	frame->data[1] \|= CAN_ERR_CRTL_RX_WARNING;
	if ((priv->shadow_statflg & MSCAN_TSTAT_MSK) <
	(canrflg & MSCAN_TSTAT_MSK))
	frame->data[1] \|= CAN_ERR_CRTL_TX_WARNING;
	break;
	case CAN_STATE_ERROR_PASSIVE:
	frame->can_id \|= CAN_ERR_CRTL;
	priv->can.can_stats.error_passive++;
	frame->data[1] \|= CAN_ERR_CRTL_RX_PASSIVE;
	break;
	case CAN_STATE_BUS_OFF:
	frame->can_id \|= CAN_ERR_BUSOFF;
	/*
	* The MSCAN on the MPC5200 does recover from bus-off
	* automatically. To avoid that we stop the chip doing
	* a light-weight stop (we are in irq-context).
	*/
	out_8(&regs->cantier, 0);
	out_8(&regs->canrier, 0);
	setbits8(&regs->canctl0, MSCAN_SLPRQ \| MSCAN_INITRQ);
	can_bus_off(dev);
	break;
	default:
	break;
	}
	}
	priv->shadow_statflg = canrflg & MSCAN_STAT_MSK;
	frame->can_dlc = CAN_ERR_DLC;
	out_8(&regs->canrflg, MSCAN_ERR_IF);
	}

	static int mscan_rx_poll(struct napi_struct *napi, int quota)
	{
	struct mscan_priv *priv = container_of(napi, struct mscan_priv, napi);
	struct net_device *dev = napi->dev;
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	struct net_device_stats *stats = &dev->stats;
	int npackets = 0;
	int ret = 1;
	struct sk_buff *skb;
	struct can_frame *frame;
	u8 canrflg;

	while (npackets < quota && ((canrflg = in_8(&regs->canrflg)) &
	(MSCAN_RXF \| MSCAN_ERR_IF))) {

	skb = alloc_can_skb(dev, &frame);
	if (!skb) {
	if (printk_ratelimit())
	dev_notice(dev->dev.parent, "packet dropped\n");
	stats->rx_dropped++;
	out_8(&regs->canrflg, canrflg);
	continue;
	}

	if (canrflg & MSCAN_RXF)
	mscan_get_rx_frame(dev, frame);
	else if (canrflg & MSCAN_ERR_IF)
	mscan_get_err_frame(dev, frame, canrflg);

	stats->rx_packets++;
	stats->rx_bytes += frame->can_dlc;
	npackets++;
	netif_receive_skb(skb);
	}

	if (!(in_8(&regs->canrflg) & (MSCAN_RXF \| MSCAN_ERR_IF))) {
	napi_complete(&priv->napi);
	clear_bit(F_RX_PROGRESS, &priv->flags);
	if (priv->can.state < CAN_STATE_BUS_OFF)
	out_8(&regs->canrier, priv->shadow_canrier);
	ret = 0;
	}
	return ret;
	}

	static irqreturn_t mscan_isr(int irq, void *dev_id)
	{
	struct net_device dev = (struct net_device )dev_id;
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	struct net_device_stats *stats = &dev->stats;
	u8 cantier, cantflg, canrflg;
	irqreturn_t ret = IRQ_NONE;

	cantier = in_8(&regs->cantier) & MSCAN_TXE;
	cantflg = in_8(&regs->cantflg) & cantier;

	if (cantier && cantflg) {
	struct list_head tmp, pos;

	list_for_each_safe(pos, tmp, &priv->tx_head) {
	struct tx_queue_entry *entry =
	list_entry(pos, struct tx_queue_entry, list);
	u8 mask = entry->mask;

	if (!(cantflg & mask))
	continue;

	out_8(&regs->cantbsel, mask);
	stats->tx_bytes += in_8(&regs->tx.dlr);
	stats->tx_packets++;
	can_get_echo_skb(dev, entry->id);
	priv->tx_active &= ~mask;
	list_del(pos);
	}

	if (list_empty(&priv->tx_head)) {
	clear_bit(F_TX_WAIT_ALL, &priv->flags);
	clear_bit(F_TX_PROGRESS, &priv->flags);
	priv->cur_pri = 0;
	} else {
	dev->trans_start = jiffies;
	}

	if (!test_bit(F_TX_WAIT_ALL, &priv->flags))
	netif_wake_queue(dev);

	out_8(&regs->cantier, priv->tx_active);
	ret = IRQ_HANDLED;
	}

	canrflg = in_8(&regs->canrflg);
	if ((canrflg & ~MSCAN_STAT_MSK) &&
	!test_and_set_bit(F_RX_PROGRESS, &priv->flags)) {
	if (canrflg & ~MSCAN_STAT_MSK) {
	priv->shadow_canrier = in_8(&regs->canrier);
	out_8(&regs->canrier, 0);
	napi_schedule(&priv->napi);
	ret = IRQ_HANDLED;
	} else {
	clear_bit(F_RX_PROGRESS, &priv->flags);
	}
	}
	return ret;
	}

	static int mscan_do_set_mode(struct net_device *dev, enum can_mode mode)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	int ret = 0;

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

	switch (mode) {
	case CAN_MODE_START:
	if (priv->can.state <= CAN_STATE_BUS_OFF)
	mscan_set_mode(dev, MSCAN_INIT_MODE);
	ret = mscan_start(dev);
	if (ret)
	break;
	if (netif_queue_stopped(dev))
	netif_wake_queue(dev);
	break;

	default:
	ret = -EOPNOTSUPP;
	break;
	}
	return ret;
	}

	static int mscan_do_set_bittiming(struct net_device *dev)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	struct can_bittiming *bt = &priv->can.bittiming;
	u8 btr0, btr1;

	btr0 = BTR0_SET_BRP(bt->brp) \| BTR0_SET_SJW(bt->sjw);
	btr1 = (BTR1_SET_TSEG1(bt->prop_seg + bt->phase_seg1) \|
	BTR1_SET_TSEG2(bt->phase_seg2) \|
	BTR1_SET_SAM(priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES));

	dev_info(dev->dev.parent, "setting BTR0=0x%02x BTR1=0x%02x\n",
	btr0, btr1);

	out_8(&regs->canbtr0, btr0);
	out_8(&regs->canbtr1, btr1);

	return 0;
	}

	static int mscan_open(struct net_device *dev)
	{
	int ret;
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;

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

	napi_enable(&priv->napi);

	ret = request_irq(dev->irq, mscan_isr, 0, dev->name, dev);
	if (ret < 0) {
	napi_disable(&priv->napi);
	printk(KERN_ERR "%s - failed to attach interrupt\n",
	dev->name);
	return ret;
	}

	priv->open_time = jiffies;

	clrbits8(&regs->canctl1, MSCAN_LISTEN);

	ret = mscan_start(dev);
	if (ret)
	return ret;

	netif_start_queue(dev);

	return 0;
	}

	static int mscan_close(struct net_device *dev)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;

	netif_stop_queue(dev);
	napi_disable(&priv->napi);

	out_8(&regs->cantier, 0);
	out_8(&regs->canrier, 0);
	mscan_set_mode(dev, MSCAN_INIT_MODE);
	close_candev(dev);
	free_irq(dev->irq, dev);
	priv->open_time = 0;

	return 0;
	}

	static const struct net_device_ops mscan_netdev_ops = {
	.ndo_open = mscan_open,
	.ndo_stop = mscan_close,
	.ndo_start_xmit = mscan_start_xmit,
	};

	int register_mscandev(struct net_device *dev, int clock_src)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	u8 ctl1;

	ctl1 = in_8(&regs->canctl1);
	if (clock_src)
	ctl1 \|= MSCAN_CLKSRC;
	else
	ctl1 &= ~MSCAN_CLKSRC;

	ctl1 \|= MSCAN_CANE;
	out_8(&regs->canctl1, ctl1);
	udelay(100);

	/* acceptance mask/acceptance code (accept everything) */
	out_be16(&regs->canidar1_0, 0);
	out_be16(&regs->canidar3_2, 0);
	out_be16(&regs->canidar5_4, 0);
	out_be16(&regs->canidar7_6, 0);

	out_be16(&regs->canidmr1_0, 0xffff);
	out_be16(&regs->canidmr3_2, 0xffff);
	out_be16(&regs->canidmr5_4, 0xffff);
	out_be16(&regs->canidmr7_6, 0xffff);
	/* Two 32 bit Acceptance Filters */
	out_8(&regs->canidac, MSCAN_AF_32BIT);

	mscan_set_mode(dev, MSCAN_INIT_MODE);

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

	void unregister_mscandev(struct net_device *dev)
	{
	struct mscan_priv *priv = netdev_priv(dev);
	struct mscan_regs regs = (struct mscan_regs )priv->reg_base;
	mscan_set_mode(dev, MSCAN_INIT_MODE);
	clrbits8(&regs->canctl1, MSCAN_CANE);
	unregister_candev(dev);
	}
	EXPORT_SYMBOL_GPL(unregister_mscandev);

	struct net_device *alloc_mscandev(void)
	{
	struct net_device *dev;
	struct mscan_priv *priv;
	int i;

	dev = alloc_candev(sizeof(struct mscan_priv), MSCAN_ECHO_SKB_MAX);
	if (!dev)
	return NULL;
	priv = netdev_priv(dev);

	dev->netdev_ops = &mscan_netdev_ops;

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

	netif_napi_add(dev, &priv->napi, mscan_rx_poll, 8);

	priv->can.bittiming_const = &mscan_bittiming_const;
	priv->can.do_set_bittiming = mscan_do_set_bittiming;
	priv->can.do_set_mode = mscan_do_set_mode;

	for (i = 0; i < TX_QUEUE_SIZE; i++) {
	priv->tx_queue[i].id = i;
	priv->tx_queue[i].mask = 1 << i;
	}

	return dev;
	}
	EXPORT_SYMBOL_GPL(alloc_mscandev);

	MODULE_AUTHOR("Andrey Volkov <avolkov@varma-el.com>");
	MODULE_LICENSE("GPL v2");
	MODULE_DESCRIPTION("CAN port driver for a MSCAN based chips");