sunxi_can.c

/*
 * sun7i_can.c - CAN bus controller driver for sun7i
 *
 * Copyright (c) 2013 Peter Chen
 *
 * Copyright (c) 2013 Inmotion Co,. LTD
 * All right reserved.
 *
 */

#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 <mach/includes.h>

#include "sun7i_can.h"

#define DRV_NAME "sun7i_can"

MODULE_AUTHOR("Peter Chen <xingkongcp@gmail.com>");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION(DRV_NAME "CAN netdevice driver");

static struct net_device *sun7ican_dev;
static struct can_bittiming_const sun7i_can_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 sun7i_can_write_cmdreg(struct sun7i_can_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);
	writel(val, CAN_CMD_ADDR);
	spin_unlock_irqrestore(&priv->cmdreg_lock, flags);
}

static int sun7i_can_is_absent(struct sun7i_can_priv *priv)
{
	return ((readl(CAN_MSEL_ADDR) & 0xFF) == 0xFF);
}

static int sun7i_can_probe(struct net_device *dev)
{
	struct sun7i_can_priv *priv = netdev_priv(dev);

	if (sun7i_can_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 sun7i_can_priv *priv = netdev_priv(dev);
	uint32_t status = readl(CAN_MSEL_ADDR);
	int i;

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

		writel(readl(CAN_MSEL_ADDR) | RESET_MODE, CAN_MSEL_ADDR);	/* select reset mode */
		//writel(RESET_MODE, CAN_MSEL_ADDR);	/* select reset mode */
		udelay(10);
		status = readl(CAN_MSEL_ADDR);
	}

	netdev_err(dev, "setting SUN7I_CAN into reset mode failed!\n");
}

static void set_normal_mode(struct net_device *dev)
{
	struct sun7i_can_priv *priv = netdev_priv(dev);
	unsigned char status = readl(CAN_MSEL_ADDR);
	int i;

	for (i = 0; i < 100; i++) {
		/* check reset bit */
		if ((status & RESET_MODE) == 0) {
			priv->can.state = CAN_STATE_ERROR_ACTIVE;
			/* enable interrupts */
			if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
				writel(0xFFFF, CAN_INTEN_ADDR);
			else
				writel(0xFFFF & ~BERR_IRQ_EN, CAN_INTEN_ADDR);
			return;
		}

		/* set chip to normal mode */
		writel(readl(CAN_MSEL_ADDR) & (~RESET_MODE), CAN_MSEL_ADDR);
		udelay(10);
		status = readl(CAN_MSEL_ADDR);
	}

	netdev_err(dev, "setting SUN7I_CAN into normal mode failed!\n");
}


static void sun7i_can_start(struct net_device *dev)
{
	struct sun7i_can_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 */
	writel(0x0, CAN_ERRC_ADDR);

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

static int sun7i_can_set_mode(struct net_device *dev, enum can_mode mode)
{
	struct sun7i_can_priv *priv = netdev_priv(dev);

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

	switch (mode) {
	case CAN_MODE_START:
		sun7i_can_start(dev);
		if (netif_queue_stopped(dev))
			netif_wake_queue(dev);
		break;

	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int sun7i_can_set_bittiming(struct net_device *dev)
{
	struct sun7i_can_priv *priv = netdev_priv(dev);
	struct can_bittiming *bt = &priv->can.bittiming;
	u32 cfg;

	cfg = ((bt->brp - 1) & 0x3FF)
		| (((bt->sjw - 1) & 0x3) << 14)
		| (((bt->prop_seg + bt->phase_seg1 - 1) & 0xf) << 16)
		| (((bt->phase_seg2 - 1) & 0x7) << 20);
	if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
		cfg |= 0x800000;

	netdev_info(dev, "setting BITTIMING=0x%08x\n", cfg);

	set_reset_mode(dev);		//CAN_BTIME_ADDR only writable in reset mode
	writel(cfg, CAN_BTIME_ADDR);
	set_normal_mode(dev);

	return 0;
}

static int sun7i_can_get_berr_counter(const struct net_device *dev,
				    struct can_berr_counter *bec)
{
	bec->txerr = readl(CAN_ERRC_ADDR) & 0x000F;
	bec->rxerr = (readl(CAN_ERRC_ADDR) & 0x0F00) >> 16;

	return 0;
}

/*
 * initialize sun7i_can:
 *   - reset chip
 *   - set output mode
 *   - set baudrate
 *   - enable interrupts
 *   - start operating mode
 */
static void chipset_init(struct net_device *dev)
{
	u32 temp_irqen;

	/* config pins 
	 * PA16-TX, PA17-RX :3 */
	sw_gpio_setcfg(GPIOA(16), 3);
	sw_gpio_setcfg(GPIOA(17), 3);

	//enable clock
	writel(readl(0xF1C20000 + 0x6C) | (1 << 4), 0xF1C20000 + 0x6C);

	//set can controller in reset mode
	set_reset_mode(dev);

	//enable interrupt
	temp_irqen = BERR_IRQ_EN | ERR_PASSIVE_IRQ_EN
			| OR_IRQ_EN | RX_IRQ_EN;
	writel(readl(CAN_INTEN_ADDR) | temp_irqen, CAN_INTEN_ADDR);

	//return to transfer mode
	set_normal_mode(dev);
}

/*
 * 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 sun7i_can_start_xmit(struct sk_buff *skb,
					    struct net_device *dev)
{
	struct sun7i_can_priv *priv = netdev_priv(dev);
	struct can_frame *cf = (struct can_frame *)skb->data;
	uint8_t dlc;
	canid_t id;
	uint32_t temp = 0;
	uint8_t i;
	
	//wait buff ready
	while (!(readl(CAN_STA_ADDR) & TBUF_RDY));

	set_reset_mode(dev);

	writel(0xffffffff, CAN_ACPM_ADDR);

	//enter transfer mode
	set_normal_mode(dev);

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

	netif_stop_queue(dev);

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

	temp = ((id >> 30) << 6) | dlc;
	writel(temp, CAN_BUF0_ADDR);
	if (id & CAN_EFF_FLAG) {/* extern frame */
		writel(0xFF & (id >> 21), CAN_BUF1_ADDR);	//id28~21
		writel(0xFF & (id >> 13), CAN_BUF2_ADDR);  	//id20~13
		writel(0xFF & (id >> 5), CAN_BUF3_ADDR);   	//id12~5
		writel((id & 0x1F) << 3, CAN_BUF4_ADDR); 	//id4~0
		
		for (i = 0; i < dlc; i++) {
			writel(cf->data[i], CAN_BUF5_ADDR + i * 4);
		}
	} else {		/* standard frame*/	
		writel(0xFF & (id >> 3), CAN_BUF1_ADDR); 	//id28~21
		writel((id & 0x7) << 5, CAN_BUF2_ADDR);		//id20~13
		
		for (i = 0; i < dlc; i++) {
			writel(cf->data[i], CAN_BUF3_ADDR + i * 4);
		}
	}

	can_put_echo_skb(skb, dev, 0);

	while (!(readl(CAN_STA_ADDR) & TBUF_RDY));
	sun7i_can_write_cmdreg(priv, TRANS_REQ);

	return NETDEV_TX_OK;
}

static void sun7i_can_rx(struct net_device *dev)
{
	struct sun7i_can_priv *priv = netdev_priv(dev);
	struct net_device_stats *stats = &dev->stats;
	struct can_frame *cf;
	struct sk_buff *skb;
	uint8_t fi;
	canid_t id;
	int i;

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

	fi = readl(CAN_BUF0_ADDR);
	cf->can_dlc = get_can_dlc(fi & 0x0F);
	if (fi >> 7) {
		/* extended frame format (EFF) */
		id = (readl(CAN_BUF1_ADDR) << 21)	//id28~21
		    | (readl(CAN_BUF2_ADDR) << 13)	//id20~13
		    | (readl(CAN_BUF3_ADDR) << 5)	//id12~5
		    | ((readl(CAN_BUF4_ADDR) >> 3) & 0x1f);	//id4~0
		id |= CAN_EFF_FLAG;

		if ((fi >> 6) & 0x1) {	/* remote transmission request */
		id |= CAN_RTR_FLAG;
		} else {
			for (i = 0; i < cf->can_dlc; i++)
				cf->data[i] = readl(CAN_BUF5_ADDR + i * 4);
		}
	} else {
		/* standard frame format (SFF) */
		id = (readl(CAN_BUF1_ADDR) << 3)	//id28~21
		    | ((readl(CAN_BUF2_ADDR) >> 5) & 0x7);	//id20~18

		if ((fi >> 6) & 0x1) {	/* remote transmission request */
		id |= CAN_RTR_FLAG;
		} else {
			for (i = 0; i < cf->can_dlc; i++)
				cf->data[i] = readl(CAN_BUF3_ADDR + i * 4);
		}
	}

	cf->can_id = id;

	/* release receive buffer */
	sun7i_can_write_cmdreg(priv, RELEASE_RBUF);

	netif_rx(skb);

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

static int sun7i_can_err(struct net_device *dev, uint8_t isrc, uint8_t status)
{
	struct sun7i_can_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;
	uint32_t ecc, alc;

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

	if (isrc & DATA_ORUNI) {
		/* 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++;
		sun7i_can_write_cmdreg(priv, CLEAR_DOVERRUN);	/* clear bit */
	}

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

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

		ecc = readl(CAN_STA_ADDR);

		cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;

		if(ecc & BIT_ERR)
			cf->data[2] |= CAN_ERR_PROT_BIT;
		else if (ecc & FORM_ERR)
			cf->data[2] |= CAN_ERR_PROT_FORM;
		else if (ecc & STUFF_ERR)
			cf->data[2] |= CAN_ERR_PROT_STUFF;
		else {
			cf->data[2] |= CAN_ERR_PROT_UNSPEC;
			cf->data[3] = (ecc & ERR_SEG_CODE) >> 16;
		}
		/* Error occurred during transmission? */
		if ((ecc & ERR_DIR) == 0)
			cf->data[2] |= CAN_ERR_PROT_TX;
	}
	if (isrc & ERR_PASSIVE) {
		/* error passive interrupt */
		netdev_dbg(dev, "error passive interrupt\n");
		if (status & ERR_STA)
			state = CAN_STATE_ERROR_PASSIVE;
		else
			state = CAN_STATE_ERROR_ACTIVE;
	}
	if (isrc & ARB_LOST) {
		/* arbitration lost interrupt */
		netdev_dbg(dev, "arbitration lost interrupt\n");
		alc = readl(CAN_STA_ADDR);
		priv->can.can_stats.arbitration_lost++;
		stats->tx_errors++;
		cf->can_id |= CAN_ERR_LOSTARB;
		cf->data[0] = (alc & 0x1f) >> 8;
	}

	if (state != priv->can.state && (state == CAN_STATE_ERROR_WARNING ||
					 state == CAN_STATE_ERROR_PASSIVE)) {
		uint8_t rxerr = (readl(CAN_ERRC_ADDR) >> 16) & 0xFF;
		uint8_t txerr = readl(CAN_ERRC_ADDR) & 0xFF;
		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 sun7i_can_interrupt(int irq, void *dev_id)
{
	struct net_device *dev = (struct net_device *)dev_id;
	struct sun7i_can_priv *priv = netdev_priv(dev);
	struct net_device_stats *stats = &dev->stats;
	uint8_t isrc, status;
	int n = 0;

	printk(KERN_INFO "sun7ican: capture a interrupt\n");

	/* Shared interrupts and IRQ off? */
	if ((readl(CAN_INT_ADDR) & 0xF) == 0x0)
		return IRQ_NONE;

	while ((isrc = readl(CAN_INT_ADDR)) && (n < SUN7I_CAN_MAX_IRQ)) {
		n++;
		status = readl(CAN_STA_ADDR);
		/* check for absent controller due to hw unplug */
		if (sun7i_can_is_absent(priv))
			return IRQ_NONE;

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

		if (isrc & TBUF_VLD) {
			/* transmission complete interrupt */
			stats->tx_bytes += readl(CAN_RBUF_RBACK_START_ADDR) & 0xf;
			stats->tx_packets++;
			can_get_echo_skb(dev, 0);
			netif_wake_queue(dev);
		}
		if (isrc & RBUF_VLD) {
			/* receive interrupt */
			while (status & RBUF_RDY) {	//RX buffer is not empty
				sun7i_can_rx(dev);
				status = readl(CAN_STA_ADDR);
				/* check for absent controller */
				if (sun7i_can_is_absent(priv))
					return IRQ_NONE;
			}
		}
		if (isrc & (DATA_ORUNI | ERR_WRN | BUS_ERR | ERR_PASSIVE | ARB_LOST)) {
			/* error interrupt */
			if (sun7i_can_err(dev, isrc, status))
				break;
		}

		//clear the interrupt
		writel(isrc, CAN_INT_ADDR);
		udelay(10);
	}

	if (n >= SUN7I_CAN_MAX_IRQ)
		netdev_dbg(dev, "%d messages handled in ISR", n);

	return (n) ? IRQ_HANDLED : IRQ_NONE;
}
EXPORT_SYMBOL_GPL(sun7i_can_interrupt);

static int sun7i_can_open(struct net_device *dev)
{
	struct sun7i_can_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 & SUN7I_CAN_CUSTOM_IRQ_HANDLER)) {
		err = request_irq(dev->irq, sun7i_can_interrupt, priv->irq_flags,
				  dev->name, (void *)dev);
		if (err) {
			close_candev(dev);
			printk(KERN_INFO "request_irq err:%d\n", err);
			return -EAGAIN;
		}
	}

	/* init and start chi */
	sun7i_can_start(dev);
	priv->open_time = jiffies;

	netif_start_queue(dev);

	return 0;
}

static int sun7i_can_close(struct net_device *dev)
{
	struct sun7i_can_priv *priv = netdev_priv(dev);

	netif_stop_queue(dev);
	set_reset_mode(dev);

	if (!(priv->flags & SUN7I_CAN_CUSTOM_IRQ_HANDLER))
		free_irq(dev->irq, (void *)dev);

	close_candev(dev);

	priv->open_time = 0;

	return 0;
}

struct net_device *alloc_sun7icandev(int sizeof_priv)
{
	struct net_device *dev;
	struct sun7i_can_priv *priv;

	dev = alloc_candev(sizeof(struct sun7i_can_priv) + sizeof_priv,
		SUN7I_CAN_ECHO_SKB_MAX);
	if (!dev)
		return NULL;

	priv = netdev_priv(dev);

	priv->dev = dev;
	priv->can.bittiming_const = &sun7i_can_bittiming_const;
	priv->can.do_set_bittiming = sun7i_can_set_bittiming;
	priv->can.do_set_mode = sun7i_can_set_mode;
	priv->can.do_get_berr_counter = sun7i_can_get_berr_counter;
	priv->can.ctrlmode_supported = CAN_CTRLMODE_ONE_SHOT |
		CAN_CTRLMODE_LISTENONLY |
		CAN_CTRLMODE_3_SAMPLES |
		CAN_CTRLMODE_BERR_REPORTING;

	spin_lock_init(&priv->cmdreg_lock);

	if (sizeof_priv)
		priv->priv = (void *)priv + sizeof(struct sun7i_can_priv);

	return dev;
}
EXPORT_SYMBOL_GPL(alloc_sun7icandev);

void free_sun7icandev(struct net_device *dev)
{
	free_candev(dev);
}
EXPORT_SYMBOL_GPL(free_sun7icandev);

static const struct net_device_ops sun7ican_netdev_ops = {
       .ndo_open               = sun7i_can_open,
       .ndo_stop               = sun7i_can_close,
       .ndo_start_xmit         = sun7i_can_start_xmit,
};

int register_sun7icandev(struct net_device *dev)
{
	if (!sun7i_can_probe(dev))
		return -ENODEV;

	dev->flags |= IFF_ECHO;	/* support local echo */
	dev->netdev_ops = &sun7ican_netdev_ops;

	set_reset_mode(dev);
	
	return register_candev(dev);
}
EXPORT_SYMBOL_GPL(register_sun7icandev);

void unregister_sun7icandev(struct net_device *dev)
{
	set_reset_mode(dev);
	unregister_candev(dev);
}
EXPORT_SYMBOL_GPL(unregister_sun7icandev);

static __init int sun7i_can_init(void)
{
	struct sun7i_can_priv *priv;
	int err;

	sun7ican_dev = alloc_sun7icandev(0);
	if(!sun7ican_dev) {
		printk(KERN_INFO "alloc sun7icandev fail\n");
	}
	priv = netdev_priv(sun7ican_dev);
	sun7ican_dev->irq = AW_IRQ_CAN;
	priv->irq_flags = 0;
	priv->can.clock.freq = clk_get_rate(clk_get(NULL, CLK_MOD_CAN));
	chipset_init(sun7ican_dev);
	err = register_sun7icandev(sun7ican_dev);
	if(err) {
		dev_err(&sun7ican_dev->dev, "registering %s failed (err=%d)\n", DRV_NAME, err);
		goto exit_free;
	}

	dev_info(&sun7ican_dev->dev, "%s device registered (reg_base=0x%08x, irq=%d)\n",
		 DRV_NAME, CAN_BASE0, sun7ican_dev->irq);

	printk(KERN_INFO "%s CAN netdevice driver\n", DRV_NAME);

	return 0;

exit_free:
	free_sun7icandev(sun7ican_dev);

	return err;
}
module_init(sun7i_can_init);

static __exit void sun7i_can_exit(void)
{
	unregister_sun7icandev(sun7ican_dev);
	free_sun7icandev(sun7ican_dev);

	printk(KERN_INFO "%s: driver removed\n", DRV_NAME);
}
module_exit(sun7i_can_exit);