net1080.c

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/*
 * NetChip 1080 Driver (USB Host-to-Host Link)
 * Copyright (C) 2000 by David Brownell <[e-mail]>
 */

/*
 * This talks to the NetChip 1080, which can appear in "network cables"
 * and other designs.  This driver interoperates with the Win32 network
 * drivers from NetChip, using the NetChip reference design.
 *
 * The IP-over-USB protocol here may be of interest.  Embedded devices
 * could implement it at the cost of two bulk endpoints, and whatever
 * other system resources the desired IP-based applications need.
 * Some Linux palmtops could support that today.  (Devices that don't
 * support the TTL-driven data mangling of the net1080 chip won't need
 * the header/trailer support though.)
 * 
 * STATUS:
 *
 * 13-sept-2000		experimental, new
 *
 * This doesn't yet do any network hotplugging, and there's no matching
 * ifup policy script ... it should arrange bridging with "brctl", and
 * should handle static and dynamic ("pump") setups.
 *
 * RX/TX queue sizes currently fixed at one due to URB unlink problems.
 *
 * 10-oct-2000
 * usb_device_id table created. 
 *
 * 28-oct-2000
 * misc fixes; mostly, discard more TTL-mangled rx packets.
 *
 * 01-nov-2000
 * usb_device_id table support added by Adam J. Richter <[e-mail]>.
 * 
 *-------------------------------------------------------------------------*/

#include <linux/config.h>
#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/random.h>
#include <asm/unaligned.h>

#define DEBUG				// error path messages
// #define VERBOSE			// more; success messages
#define USE_TTL				// timeout our reads

#if !defined (DEBUG) && defined (CONFIG_USB_DEBUG)
#   define DEBUG
#endif
#include <linux/usb.h>


static const struct usb_device_id	products [] = {
	// reference design
	{ USB_DEVICE(0x1080, 0x525), 
	  driver_info: (unsigned long) "NetChip TurboCONNECT" },
	// Belkin, ...
	{ },		// END
};

MODULE_DEVICE_TABLE (usb, products);

static u8	node_id [ETH_ALEN];


/*-------------------------------------------------------------------------
 *
 * NetChip protocol:  ethernet framing, and only use bulk endpoints (01/81;
 * not mailboxes 02/82 or status interrupt 83).  Expects Ethernet bridging.
 * Odd USB length == always short read.
 *	- nc_header
 *	- payload, in Ethernet framing (14 byte header etc)
 *	- (optional padding byte, if needed so length is odd)
 *	- nc_trailer
 */

struct nc_header {
	u16	hdr_len;		// sizeof nc_header (LE, all)
	u16	packet_len;		// packet size
	u16	packet_id;		// detects dropped packets
#define NC_MIN_HEADER	6

	// all else is optional, and must start with:
	// u16	vendorId;		// from usb-if
	// u16	productId;
};

#define	NC_PAD_BYTE	((unsigned char)0xAC)

struct nc_trailer {
	u16	packet_id;
};

// packetsize == f(mtu setting), with upper limit
#define NC_MAX_PACKET(mtu) (sizeof (struct nc_header) \
				+ (mtu) \
				+ 1 \
				+ sizeof (struct nc_trailer))
#define MAX_PACKET	8191

// zero means no timeout; else, how long a 64 byte bulk
// read may be queued before HW flushes it.
#define	NC_READ_TTL	((u8)255)	// ms


/*-------------------------------------------------------------------------*/

// list of all devices we manage
static DECLARE_MUTEX (net1080_mutex);
static LIST_HEAD (net1080_list);


// Nineteen USB 1.1 max size bulk transactions per frame, max.
#if 0
#define	RX_QLEN		4
#define	TX_QLEN		4

#else
// unlink_urbs() has probs on OHCI without test8-pre patches.
#define	RX_QLEN		1
#define	TX_QLEN		1
#endif

enum skb_state {
	illegal = 0,
	tx_start, tx_done,
	rx_start, rx_done, rx_cleanup
};

struct skb_data {	// skb->cb is one of these
	struct urb		*urb;
	struct net1080		*dev;
	enum skb_state		state;
	size_t			length;
};


struct net1080 {
	// housekeeping
	struct usb_device	*udev;
	const struct usb_device_id	*prod_info;
	struct semaphore	mutex;
	struct list_head	dev_list;
	wait_queue_head_t	*wait;

	// protocol/interface state
	struct net_device	net;
	struct net_device_stats	stats;
	u16			packet_id;

	// various kinds of pending driver work
	struct sk_buff_head	rxq;
	struct sk_buff_head	txq;
	struct sk_buff_head	done;
	struct tasklet_struct	bh;
};

#define	mutex_lock(x)	down(x)
#define	mutex_unlock(x)	up(x)

static void defer_bh (struct net1080 *dev, struct sk_buff *skb)
{
	unsigned long	flags;

	skb_unlink (skb);
	spin_lock_irqsave (&dev->done.lock, flags);
	__skb_queue_tail (&dev->done, skb);
	if (dev->done.qlen == 1)
		tasklet_schedule (&dev->bh);
	spin_unlock_irqrestore (&dev->done.lock, flags);
}

/*-------------------------------------------------------------------------
 *
 * We ignore most registers and EEPROM contents.
 */

#define	REG_USBCTL	((u8)0x04)
#define REG_TTL		((u8)0x10)
#define REG_STATUS	((u8)0x11)

/*
 * Vendor specific requests to read/write data
 */

#define	REQUEST_REGISTER	((u8)0x10)
#define	REQUEST_EEPROM		((u8)0x11)

#define	CONTROL_TIMEOUT		(500)			/* msec */

static int
vendor_read (struct net1080 *dev, u8 req, u8 regnum, u16 *retval_ptr)
{
	int status = usb_control_msg (dev->udev,
		usb_rcvctrlpipe (dev->udev, 0),
		req,
		USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
		0, regnum,
		retval_ptr, sizeof *retval_ptr,
		CONTROL_TIMEOUT);
	if (status > 0)
		status = 0;
	if (!status)
		le16_to_cpus (retval_ptr);
	return status;
}

static inline int
register_read (struct net1080 *dev, u8 regnum, u16 *retval_ptr)
{
	return vendor_read (dev, REQUEST_REGISTER, regnum, retval_ptr);
}

// without retval, this can become fully async (usable in_interrupt)
static void
vendor_write (struct net1080 *dev, u8 req, u8 regnum, u16 value)
{
	usb_control_msg (dev->udev,
		usb_sndctrlpipe (dev->udev, 0),
		req,
		USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
		value, regnum,
		0, 0,			// data is in setup packet
		CONTROL_TIMEOUT);
}

static inline void
register_write (struct net1080 *dev, u8 regnum, u16 value)
{
	vendor_write (dev, REQUEST_REGISTER, regnum, value);
}


#if 0
static void dump_registers (struct net1080 *dev)
{
	u8	reg;
	u16	value;

	dbg ("%s registers:", dev->net.name);
	for (reg = 0; reg < 0x20; reg++) {
		int retval;

		// reading some registers is trouble
		if (reg >= 0x08 && reg <= 0xf)
			continue;
		if (reg >= 0x12 && reg <= 0x1e)
			continue;

		retval = register_read (dev, reg, &value);
		if (retval < 0)
			dbg ("%s reg [0x%x] ==> error %d",
				dev->net.name, reg, retval);
		else
			dbg ("%s reg [0x%x] = 0x%x",
				dev->net.name, reg, value);
	}
}
#endif


/*-------------------------------------------------------------------------
 *
 * Control register
 */

#define	USBCTL_WRITABLE_MASK	0x1f0f
// bits 15-13 reserved, r/o
#define	USBCTL_ENABLE_LANG	(1 << 12)
#define	USBCTL_ENABLE_MFGR	(1 << 11)
#define	USBCTL_ENABLE_PROD	(1 << 10)
#define	USBCTL_ENABLE_SERIAL	(1 << 9)
#define	USBCTL_ENABLE_DEFAULTS	(1 << 8)
// bits 7-4 reserved, r/o
#define	USBCTL_FLUSH_OTHER	(1 << 3)
#define	USBCTL_FLUSH_THIS	(1 << 2)
#define	USBCTL_DISCONN_OTHER	(1 << 1)
#define	USBCTL_DISCONN_THIS	(1 << 0)

#ifdef DEBUG
static void dump_usbctl (struct net1080 *dev, u16 usbctl)
{
	dbg ("%s: USB %d dev %d usbctl 0x%x:%s%s%s%s%s;"
			" this%s%s;"
			" other%s%s; r/o 0x%x",
		dev->net.name,
		dev->udev->bus->busnum, dev->udev->devnum,
		usbctl,
		(usbctl & USBCTL_ENABLE_LANG) ? " lang" : "",
		(usbctl & USBCTL_ENABLE_MFGR) ? " mfgr" : "",
		(usbctl & USBCTL_ENABLE_PROD) ? " prod" : "",
		(usbctl & USBCTL_ENABLE_SERIAL) ? " serial" : "",
		(usbctl & USBCTL_ENABLE_DEFAULTS) ? " defaults" : "",

		(usbctl & USBCTL_FLUSH_OTHER) ? " FLUSH" : "",
		(usbctl & USBCTL_DISCONN_OTHER) ? " DIS" : "",
		(usbctl & USBCTL_FLUSH_THIS) ? " FLUSH" : "",
		(usbctl & USBCTL_DISCONN_THIS) ? " DIS" : "",
		usbctl & ~USBCTL_WRITABLE_MASK
		);
}
#else
static inline void dump_usbctl (struct net1080 *dev, u16 usbctl) {}
#endif

/*-------------------------------------------------------------------------
 *
 * Status register
 */

#define	STATUS_PORT_A		(1 << 15)

#define	STATUS_CONN_OTHER	(1 << 14)
#define	STATUS_SUSPEND_OTHER	(1 << 13)
#define	STATUS_MAILBOX_OTHER	(1 << 12)
#define	STATUS_PACKETS_OTHER(n)	(((n) >> 8) && 0x03)

#define	STATUS_CONN_THIS	(1 << 6)
#define	STATUS_SUSPEND_THIS	(1 << 5)
#define	STATUS_MAILBOX_THIS	(1 << 4)
#define	STATUS_PACKETS_THIS(n)	(((n) >> 0) && 0x03)

#define	STATUS_UNSPEC_MASK	0x0c8c
#define	STATUS_NOISE_MASK 	((u16)~(0x0303|STATUS_UNSPEC_MASK))


#ifdef DEBUG
static void dump_status (struct net1080 *dev, u16 status)
{
	dbg ("%s: USB %d dev %d status 0x%x:"
			" this (%c) PKT=%d%s%s%s;"
			" other PKT=%d%s%s%s; unspec 0x%x",
		dev->net.name,
		dev->udev->bus->busnum, dev->udev->devnum,
		status,

		// XXX the packet counts don't seem right
		// (1 at reset, not 0); maybe UNSPEC too

		(status & STATUS_PORT_A) ? 'A' : 'B',
		STATUS_PACKETS_THIS (status),
		(status & STATUS_CONN_THIS) ? " CON" : "",
		(status & STATUS_SUSPEND_THIS) ? " SUS" : "",
		(status & STATUS_MAILBOX_THIS) ? " MBOX" : "",

		STATUS_PACKETS_OTHER (status),
		(status & STATUS_CONN_OTHER) ? " CON" : "",
		(status & STATUS_SUSPEND_OTHER) ? " SUS" : "",
		(status & STATUS_MAILBOX_OTHER) ? " MBOX" : "",

		status & STATUS_UNSPEC_MASK
		);
}
#else
static inline void dump_status (struct net1080 *dev, u16 status) {}
#endif

/*-------------------------------------------------------------------------
 *
 * TTL register
 */

#define	TTL_THIS(ttl)	(0x00ff & ttl)
#define	TTL_OTHER(ttl)	(0x00ff & (ttl >> 8))
#define MK_TTL(this,other)	((u16)(((other)<<8)|(0x00ff&(this))))

#ifdef DEBUG
static void dump_ttl (struct net1080 *dev, u16 ttl)
{
	dbg ("%s: USB %d dev %d ttl 0x%x this = %d, other = %d",
		dev->net.name,
		dev->udev->bus->busnum, dev->udev->devnum,
		ttl,

		TTL_THIS (ttl),
		TTL_OTHER (ttl)
		);
}
#else
static inline void dump_ttl (struct net1080 *dev, u16 ttl) {}
#endif

#define	RUN_CONTEXT (in_irq () ? "in_irq" \
			: (in_interrupt () ? "in_interrupt" : "can sleep"))

/*-------------------------------------------------------------------------*/

// ensure that the device is in a known state before using it.

// preconditions:
//	caller owns the device mutex
//	caller has a process context

static int net1080_reset (struct net1080 *dev)
{
	u16		usbctl, status, ttl;
	int		retval;

	if ((retval = register_read (dev, REG_STATUS, &status)) < 0) {
		dbg ("can't read dev %d status: %d", dev->udev->devnum, retval);
		goto done;
	}
	dump_status (dev, status);

	if ((retval = register_read (dev, REG_USBCTL, &usbctl)) < 0) {
		dbg ("can't read USBCTL, %d", retval);
		goto done;
	}
	dump_usbctl (dev, usbctl);

	register_write (dev, REG_USBCTL,
			USBCTL_FLUSH_THIS | USBCTL_FLUSH_OTHER);

	if ((retval = register_read (dev, REG_TTL, &ttl)) < 0) {
		dbg ("can't read TTL, %d", retval);
		goto done;
	}
	dump_ttl (dev, ttl);

#ifdef	USE_TTL
	// Have the chip flush reads that seem to be starving for read
	// bandwidth ... or we're otherwise reading.  Note, Win32 drivers
	// may change our read TTL for us.

	register_write (dev, REG_TTL,
			MK_TTL (NC_READ_TTL, TTL_OTHER (ttl)) );
	dbg ("%s: assigned TTL, %d ms", dev->net.name, NC_READ_TTL);
#endif

	info ("%s: %s, port %c on USB %d dev %d, peer %sconnected",
		dev->net.name, (char *) dev->prod_info->driver_info,
		(status & STATUS_PORT_A) ? 'A' : 'B',
		dev->udev->bus->busnum,
		dev->udev->devnum,
		(status & STATUS_CONN_OTHER) ? "" : "dis"
		);
	retval = 0;

done:
	return retval;
}


/*-------------------------------------------------------------------------
 *
 * Network Device Driver support (peer link to USB Host)
 *
 --------------------------------------------------------------------------*/

static int net1080_change_mtu (struct net_device *net, int new_mtu)
{
	if ((new_mtu < 0) || NC_MAX_PACKET (new_mtu) > MAX_PACKET)
		return -EINVAL;
	net->mtu = new_mtu;
	return 0;
}

/*-------------------------------------------------------------------------*/

static struct net_device_stats *net1080_get_stats (struct net_device *net)
{
	return &((struct net1080 *) net->priv)->stats;
}

/*-------------------------------------------------------------------------*/

static void rx_complete (struct urb *urb);

static void rx_submit (struct net1080 *dev, struct urb *urb, int flags)
{
	struct sk_buff		*skb;
	struct skb_data		*entry;
	int			retval = 0;
	unsigned long		lockflags;

	if ((skb = alloc_skb (NC_MAX_PACKET (dev->net.mtu), flags)) == 0) {
		err ("no rx skb");
		tasklet_schedule (&dev->bh);
		usb_free_urb (urb);
		return;
	}

	entry = (struct skb_data *) skb->cb;
	entry->urb = urb;
	entry->dev = dev;
	entry->state = rx_start;
	entry->length = 0;

	FILL_BULK_URB (urb, dev->udev, usb_rcvbulkpipe (dev->udev, 1),
			skb->data, skb->truesize, rx_complete, skb);
	urb->transfer_flags |= USB_QUEUE_BULK;

	spin_lock_irqsave (&dev->rxq.lock, lockflags);
	if (!netif_queue_stopped (&dev->net)) {
		if ((retval = usb_submit_urb (urb)) != 0) {
			err ("%s rx submit, %d", dev->net.name, retval);
			tasklet_schedule (&dev->bh);
		} else {
			__skb_queue_tail (&dev->rxq, skb);
		}
	} else {
		dbg ("rx: stopped");
		retval = -ENOLINK;
	}
	spin_unlock_irqrestore (&dev->rxq.lock, lockflags);
	if (retval) {
		dev_kfree_skb_any (skb);
		usb_free_urb (urb);
	}
}


/*-------------------------------------------------------------------------*/

static void rx_complete (struct urb *urb)
{
	struct sk_buff		*skb = (struct sk_buff *) urb->context;
	struct skb_data		*entry = (struct skb_data *) skb->cb;
	struct net1080		*dev = entry->dev;
	int			urb_status = urb->status;

	urb->dev = 0;
	skb->len = urb->actual_length;
	entry->state = rx_done;
	entry->urb = 0;

	if ((urb->transfer_flags & USB_ASYNC_UNLINK) != 0) {
		dbg ("rx ... shutting down");
		usb_free_urb (urb);
		urb = 0;
	}

	switch (urb_status) {
	    // success
	    case 0:
		if (!(skb->len & 0x01)) {
			entry->state = rx_cleanup;
			dev->stats.rx_errors++;
			dev->stats.rx_length_errors++;
			dbg ("even rx len %d", skb->len);
		} else if (skb->len > MAX_PACKET) {
			entry->state = rx_cleanup;
			dev->stats.rx_errors++;
			dev->stats.rx_frame_errors++;
			dbg ("rx too big, %d", skb->len);
		}
		break;

	    // hardware-reported interface shutdown ... which we
	    // typically see before khubd calls disconnect()
	    case -ETIMEDOUT:		// usb-ohci
	    case -EILSEQ:		// *uhci ... "crc"/timeout error