/*
 * SCCn ethernet
 */

#include "u.h"
#include "lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#include "../port/error.h"
#include "../port/netif.h"

#include "etherif.h"

enum {
	Nrdre		= 16,	/* receive descriptor ring entries */
	Ntdre		= 16,	/* transmit descriptor ring entries */

	Rbsize		= ETHERMAXTU+4,		/* ring buffer size (+4 for CRC) */
	Bufsize		= (Rbsize+7)&~7,	/* aligned */
};

enum {
	/* ether-specific Rx BD bits */
	RxMiss=		1<<8,
	RxeLG=		1<<5,
	RxeNO=		1<<4,
	RxeSH=		1<<3,
	RxeCR=		1<<2,
	RxeOV=		1<<1,
	RxeCL=		1<<0,
	RxError=		(RxeLG|RxeNO|RxeSH|RxeCR|RxeOV|RxeCL),	/* various error flags */

	/* ether-specific Tx BD bits */
	TxPad=		1<<14,	/* pad short frames */
	TxTC=		1<<10,	/* transmit CRC */
	TxeDEF=		1<<9,
	TxeHB=		1<<8,
	TxeLC=		1<<7,
	TxeRL=		1<<6,
	TxeUN=		1<<1,
	TxeCSL=		1<<0,

	/* scce */
	RXB=	1<<0,
	TXB=	1<<1,
	BSY=		1<<2,
	RXF=		1<<3,
	TXE=		1<<4,

	/* psmr */
	PRO=	1<<9,	/* promiscuous mode */

	/* gsmrl */
	ENR=	1<<5,
	ENT=	1<<4,

	/* port A */
	RXD1=	SIBIT(15),
	TXD1=	SIBIT(14),

	/* port B */
	RTS1=	IBIT(19),

	/* port C */
	CTS1=	SIBIT(11),
	CD1=	SIBIT(10),
};

typedef struct Etherparam Etherparam;
struct Etherparam {
	SCCparam;
	ulong	c_pres;		/* preset CRC */
	ulong	c_mask;		/* constant mask for CRC */
	ulong	crcec;		/* CRC error counter */
	ulong	alec;		/* alighnment error counter */
	ulong	disfc;		/* discard frame counter */
	ushort	pads;		/* short frame PAD characters */
	ushort	ret_lim;	/* retry limit threshold */
	ushort	ret_cnt;	/* retry limit counter */
	ushort	mflr;		/* maximum frame length reg */
	ushort	minflr;		/* minimum frame length reg */
	ushort	maxd1;		/* maximum DMA1 length reg */
	ushort	maxd2;		/* maximum DMA2 length reg */
	ushort	maxd;		/* rx max DMA */
	ushort	dma_cnt;	/* rx dma counter */
	ushort	max_b;		/* max bd byte count */
	ushort	gaddr[4];		/* group address filter */
	ulong	tbuf0_data0;	/* save area 0 - current frm */
	ulong	tbuf0_data1;	/* save area 1 - current frm */
	ulong	tbuf0_rba0;
	ulong	tbuf0_crc;
	ushort	tbuf0_bcnt;
	ushort	paddr[3];	/* physical address LSB to MSB increasing */
	ushort	p_per;		/* persistence */
	ushort	rfbd_ptr;	/* rx first bd pointer */
	ushort	tfbd_ptr;	/* tx first bd pointer */
	ushort	tlbd_ptr;	/* tx last bd pointer */
	ulong	tbuf1_data0;	/* save area 0 - next frame */
	ulong	tbuf1_data1;	/* save area 1 - next frame */
	ulong	tbuf1_rba0;
	ulong	tbuf1_crc;
	ushort	tbuf1_bcnt;
	ushort	tx_len;		/* tx frame length counter */
	ushort	iaddr[4];		/* individual address filter*/
	ushort	boff_cnt;	/* back-off counter */
	ushort	taddr[3];	/* temp address */
};

typedef struct {
	Lock;
	int	port;
	int	init;
	int	active;
	SCC*	scc;
	CPMdev*	cpm;

	Ring;

	ulong	interrupts;			/* statistics */
	ulong	deferred;
	ulong	heartbeat;
	ulong	latecoll;
	ulong	retrylim;
	ulong	underrun;
	ulong	overrun;
	ulong	carrierlost;
	ulong	retrycount;
} Ctlr;

static	int	sccid[] = {-1, CPscc1, CPscc2, CPscc3, CPscc4};

static void
attach(Ether *ether)
{
	Ctlr *ctlr;

	ctlr = ether->ctlr;
	ctlr->active = 1;
	ctlr->scc->gsmrl |= ENR|ENT;
	eieio();
}

static void
closed(Ether *ether)
{
	Ctlr *ctlr;

	ctlr = ether->ctlr;
	if(0){
		sccxstop(ctlr->cpm);
		ilock(ctlr);
		ctlr->active = 0;
		iunlock(ctlr);
	}
}

static void
promiscuous(void* arg, int on)
{
	Ether *ether;
	Ctlr *ctlr;

	ether = (Ether*)arg;
	ctlr = ether->ctlr;

	ilock(ctlr);
	if(on || ether->nmaddr)
		ctlr->scc->psmr |= PRO;
	else
		ctlr->scc->psmr &= ~PRO;
	iunlock(ctlr);
}

static void
multicast(void* arg, uchar *addr, int on)
{
	Ether *ether;
	Ctlr *ctlr;

	USED(addr, on);	/* if on, could SetGroupAddress; if !on, it's hard */

	ether = (Ether*)arg;
	ctlr = ether->ctlr;

	ilock(ctlr);
	if(ether->prom || ether->nmaddr)
		ctlr->scc->psmr |= PRO;
	else
		ctlr->scc->psmr &= ~PRO;
	iunlock(ctlr);
}

static void
txstart(Ether *ether)
{
	int len;
	Ctlr *ctlr;
	Block *b;
	BD *dre;

	ctlr = ether->ctlr;
	if(ctlr->init)
		return;
	while(ctlr->ntq < Ntdre-1){
		b = qget(ether->oq);
		if(b == 0)
			break;

		dre = &ctlr->tdr[ctlr->tdrh];
		if(dre->status & BDReady)
			panic("ether: txstart");
	
		/*
		 * Give ownership of the descriptor to the chip, increment the
		 * software ring descriptor pointer and tell the chip to poll.
		 */
		len = BLEN(b);
		dcflush(b->rp, len);
		if(ctlr->txb[ctlr->tdrh] != nil)
			panic("scc/ether: txstart");
		ctlr->txb[ctlr->tdrh] = b;
		if((ulong)b->rp&1)
			panic("scc/ether: txstart align");	/* TO DO: ensure alignment */
		dre->addr = PADDR(b->rp);
		dre->length = len;
		eieio();
		dre->status = (dre->status & BDWrap) | BDReady|TxPad|BDInt|BDLast|TxTC;
		eieio();
		ctlr->scc->todr = 1<<15;	/* transmit now */
		eieio();
		ctlr->ntq++;
		ctlr->tdrh = NEXT(ctlr->tdrh, Ntdre);
	}
}

static void
transmit(Ether* ether)
{
	Ctlr *ctlr;

	ctlr = ether->ctlr;
	ilock(ctlr);
	txstart(ether);
	iunlock(ctlr);
}

static void
interrupt(Ureg*, Ether *ether)
{
	int len, events, status;
	Ctlr *ctlr;
	BD *dre;
	Block *b;

	ctlr = ether->ctlr;
	if(!ctlr->active)
		return;	/* not ours */

	/*
	 * Acknowledge all interrupts and whine about those that shouldn't
	 * happen.
	 */
	events = ctlr->scc->scce;
	eieio();
	ctlr->scc->scce = events;
	eieio();
	ctlr->interrupts++;

	if(events & (TXE|BSY|RXB)){
		if(events & RXB)
			ctlr->overrun++;
		if(events & TXE)
			ether->oerrs++;
		if(0 || events & TXE)
			print("ETHER.SCC#%d: scce = 0x%uX\n", ether->ctlrno, events);
	}
	/*
	 * Receiver interrupt: run round the descriptor ring logging
	 * errors and passing valid receive data up to the higher levels
	 * until we encounter a descriptor still owned by the chip.
	 */
	if(events & (RXF|RXB) || 1){
		dre = &ctlr->rdr[ctlr->rdrx];
		while(((status = dre->status) & BDEmpty) == 0){
			if(status & RxError || (status & (BDFirst|BDLast)) != (BDFirst|BDLast)){
				if(status & (RxeLG|RxeSH))
					ether->buffs++;
				if(status & RxeNO)
					ether->frames++;
				if(status & RxeCR)
					ether->crcs++;
				if(status & RxeOV)
					ether->overflows++;
				//print("eth rx: %ux\n", status);
			}
			else{
				/*
				 * We have a packet. Read it in.
				 */
				len = dre->length-4;
				if((b = iallocb(len)) != 0){
					memmove(b->wp, KADDR(dre->addr), len);
					b->wp += len;
					etheriq(ether, b, 1);
					dcflush(KADDR(dre->addr), len);
				}else
					ether->soverflows++;
			}

			/*
			 * Finished with this descriptor, reinitialise it,
			 * give it back to the chip, then on to the next...
			 */
			dre->length = 0;
			dre->status = (status & BDWrap) | BDEmpty | BDInt;
			eieio();

			ctlr->rdrx = NEXT(ctlr->rdrx, Nrdre);
			dre = &ctlr->rdr[ctlr->rdrx];
		}
	}

	/*
	 * Transmitter interrupt: handle anything queued for a free descriptor.
	 */
	if(events & TXB){
		lock(ctlr);
		while(ctlr->ntq){
			dre = &ctlr->tdr[ctlr->tdri];
			status = dre->status;
			if(status & BDReady)
				break;
			if(status & TxeDEF)
				ctlr->deferred++;
			if(status & TxeHB)
				ctlr->heartbeat++;
			if(status & TxeLC)
				ctlr->latecoll++;
			if(status & TxeRL)
				ctlr->retrylim++;
			if(status & TxeUN)
				ctlr->underrun++;
			if(status & TxeCSL)
				ctlr->carrierlost++;
			ctlr->retrycount += (status>>2)&0xF;
			b = ctlr->txb[ctlr->tdri];
			if(b == nil)
				panic("scce/interrupt: bufp");
			ctlr->txb[ctlr->tdri] = nil;
			freeb(b);
			ctlr->ntq--;
			ctlr->tdri = NEXT(ctlr->tdri, Ntdre);
		}
		txstart(ether);
		unlock(ctlr);
	}
	if(events & TXE)
		cpmop(ctlr->cpm, RestartTx, 0);
}

static long
ifstat(Ether* ether, void* a, long n, ulong offset)
{
	char *p;
	int len;
	Ctlr *ctlr;

	if(n == 0)
		return 0;

	ctlr = ether->ctlr;

	p = malloc(READSTR);
	len = snprint(p, READSTR, "interrupts: %lud\n", ctlr->interrupts);
	len += snprint(p+len, READSTR-len, "carrierlost: %lud\n", ctlr->carrierlost);
	len += snprint(p+len, READSTR-len, "heartbeat: %lud\n", ctlr->heartbeat);
	len += snprint(p+len, READSTR-len, "retrylimit: %lud\n", ctlr->retrylim);
	len += snprint(p+len, READSTR-len, "retrycount: %lud\n", ctlr->retrycount);
	len += snprint(p+len, READSTR-len, "latecollisions: %lud\n", ctlr->latecoll);
	len += snprint(p+len, READSTR-len, "rxoverruns: %lud\n", ctlr->overrun);
	len += snprint(p+len, READSTR-len, "txunderruns: %lud\n", ctlr->underrun);
	snprint(p+len, READSTR-len, "framesdeferred: %lud\n", ctlr->deferred);
	n = readstr(offset, a, n, p);
	free(p);

	return n;
}

/*
 * This follows the MPC823 user guide: section16.9.23.7's initialisation sequence,
 * except that it sets the right bits for the MPC823ADS board when SCC2 is used,
 * and those for the 860/821 development board for SCC1.
 */
static void
sccsetup(Ctlr *ctlr, SCC *scc, uchar *ea)
{
	int i, rcs, tcs, w;
	Etherparam *p;
	IMM *io;


	i = 2*(ctlr->port-1);
	io = ioplock();
	w = (TXD1|RXD1)<<i;	/* TXDn and RXDn in port A */
	io->papar |= w;	/* enable TXDn and RXDn pins */
	io->padir &= ~w;
	io->paodr &= ~w;	/* not open drain */

	w = (CD1|CTS1)<<i;	/* CLSN and RENA: CDn and CTSn in port C */
	io->pcpar &= ~w;	/* enable CLSN (CTSn) and RENA (CDn) */
	io->pcdir &= ~w;
	io->pcso |= w;
	iopunlock();

	/* clocks and transceiver control: details depend on the board's wiring */
	archetherenable(sccid[ctlr->port], &rcs, &tcs);

	sccnmsi(ctlr->port, rcs, tcs);	/* connect the clocks */

	p = ctlr->cpm->param;
	memset(p, 0, sizeof(*p));
	p->rfcr = 0x18;
	p->tfcr = 0x18;
	p->mrblr = Bufsize;
	p->rbase = PADDR(ctlr->rdr);
	p->tbase = PADDR(ctlr->tdr);

	cpmop(ctlr->cpm, InitRxTx, 0);

	p->c_pres = ~0;
	p->c_mask = 0xDEBB20E3;
	p->crcec = 0;
	p->alec = 0;
	p->disfc = 0;
	p->pads = 0x8888;
	p->ret_lim = 0xF;
	p->mflr = Rbsize;
	p->minflr = ETHERMINTU+4;
	p->maxd1 = Bufsize;
	p->maxd2 = Bufsize;
	p->p_per = 0;	/* only moderate aggression */

	for(i=0; i<Eaddrlen; i+=2)
		p->paddr[2-i/2] = (ea[i+1]<<8)|ea[i];	/* it's not the obvious byte order */

	scc->psmr = (2<<10)|(5<<1);	/* 32-bit CRC, ignore 22 bits before SFD */
	scc->dsr = 0xd555;
	scc->gsmrh = 0;	/* normal operation */
	scc->gsmrl = (1<<28)|(4<<21)|(1<<19)|0xC;	/* transmit clock invert, 48 bit preamble, repetitive 10 preamble, ethernet */
	eieio();
	scc->scce = ~0;	/* clear all events */
	eieio();
	scc->sccm = TXE | RXF | TXB;	/* enable interrupts */
	eieio();

	io = ioplock();
	w = RTS1<<(ctlr->port-1);	/* enable TENA pin (RTSn) */
	io->pbpar |= w;
	io->pbdir |= w;
	iopunlock();

	/* gsmrl enable is deferred until attach */
}

static int
reset(Ether* ether)
{
	uchar ea[Eaddrlen];
	CPMdev *cpm;
	Ctlr *ctlr;
	SCC *scc;

	if(m->speed < 24){
		print("%s ether: system speed must be >= 24MHz for ether use\n", ether->type);
		return -1;
	}

	if(!(ether->port >= 1 && ether->port <= 4)){
		print("%s ether: no SCC port %lud\n", ether->type, ether->port);
		return -1;
	}

	cpm = cpmdev(sccid[ether->port]);
	if(cpm == nil)
		return -1;
	ether->irq = VectorCPIC + cpm->irq;
	scc = cpm->regs;
	ctlr = malloc(sizeof(*ctlr));
	ether->ctlr = ctlr;
	memset(ctlr, 0, sizeof(*ctlr));
	ctlr->cpm = cpm;
	ctlr->scc = scc;
	ctlr->port = ether->port;

	if(ioringinit(ctlr, Nrdre, Ntdre, Bufsize) < 0)
		panic("etherscc init");

	sccsetup(ctlr, scc, ether->ea);

	ether->mbps = 10;	/* TO DO: could be 100mbps on 860T */
	ether->attach = attach;
	ether->closed = closed;
	ether->transmit = transmit;
	ether->interrupt = interrupt;
	ether->ifstat = ifstat;

	ether->arg = ether;
	ether->promiscuous = promiscuous;
	ether->multicast = multicast;

	/*
	 * Until we know where to find it, insist that the plan9.ini
	 * entry holds the Ethernet address.
	 */
	memset(ea, 0, Eaddrlen);
	if(memcmp(ea, ether->ea, Eaddrlen) == 0){
		print("no ether address");
		return -1;
	}

	return 0;
}

void
etherscclink(void)
{
	addethercard("SCC", reset);
	addethercard("SCC2", reset);
}