/*	mba.c	4.13	81/03/03	*/

#include "mba.h"
#if NMBA > 0
/*
 * Massbus driver; arbitrates massbus using device
 * driver routines.  This module provides common functions.
 */
#include "../h/param.h"
#include "../h/systm.h"
#include "../h/dk.h"
#include "../h/buf.h"
#include "../h/conf.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/proc.h"
#include "../h/map.h"
#include "../h/pte.h"
#include "../h/mba.h"
#include "../h/mtpr.h"
#include "../h/vm.h"

char	mbasr_bits[] = MBASR_BITS;
/*
 * Start activity on a massbus device.
 * We are given the device's mba_info structure and activate
 * the device via the unit start routine.  The unit start
 * routine may indicate that it is finished (e.g. if the operation
 * was a ``sense'' on a tape drive), that the (multi-ported) unit
 * is busy (we will get an interrupt later), that it started the
 * unit (e.g. for a non-data transfer operation), or that it has
 * set up a data transfer operation and we should start the massbus adaptor.
 */
mbustart(mi)
	register struct mba_info *mi;
{
	register struct mba_drv *mdp;	/* drive registers */
	register struct buf *bp;	/* i/o operation at head of queue */
	register struct mba_hd *mhp;	/* header for mba device is on */

loop:
	/*
	 * Get the first thing to do off device queue.
	 */
	bp = mi->mi_tab.b_actf;
	if (bp == NULL)
		return;
	mdp = mi->mi_drv;
	/*
	 * Let the drivers unit start routine have at it
	 * and then process the request further, per its instructions.
	 */
	switch ((*mi->mi_driver->md_ustart)(mi)) {

	case MBU_NEXT:		/* request is complete (e.g. ``sense'') */
		mi->mi_tab.b_active = 0;
		mi->mi_tab.b_actf = bp->av_forw;
		iodone(bp);
		goto loop;

	case MBU_DODATA:	/* all ready to do data transfer */
		/*
		 * Queue the device mba_info structure on the massbus
		 * mba_hd structure for processing as soon as the
		 * data path is available.
		 */
		mhp = mi->mi_hd;
		mi->mi_forw = NULL;
		if (mhp->mh_actf == NULL)
			mhp->mh_actf = mi;
		else
			mhp->mh_actl->mi_forw = mi;
		mhp->mh_actl = mi;
		/*
		 * If data path is idle, start transfer now.
		 * In any case the device is ``active'' waiting for the
		 * data to transfer.
		 */
		mi->mi_tab.b_active = 1;
		if (mhp->mh_active == 0)
			mbstart(mhp);
		return;

	case MBU_STARTED:	/* driver started a non-data transfer */
		/*
		 * Mark device busy during non-data transfer
		 * and count this as a ``seek'' on the device.
		 */
		if (mi->mi_dk >= 0)
			dk_seek[mi->mi_dk]++;
		mi->mi_tab.b_active = 1;
		return;

	case MBU_BUSY:		/* dual port drive busy */
		/*
		 * We mark the device structure so that when an
		 * interrupt occurs we will know to restart the unit.
		 */
		mi->mi_tab.b_flags |= B_BUSY;
		return;

	default:
		panic("mbustart");
	}
}

/*
 * Start an i/o operation on the massbus specified by the argument.
 * We peel the first operation off its queue and insure that the drive
 * is present and on-line.  We then use the drivers start routine
 * (if any) to prepare the drive, setup the massbus map for the transfer
 * and start the transfer.
 */
mbstart(mhp)
	register struct mba_hd *mhp;
{
	register struct mba_info *mi;
	struct buf *bp;
	register struct mba_regs *mbp;

loop:
	/*
	 * Look for an operation at the front of the queue.
	 */
	if ((mi = mhp->mh_actf) == NULL)
		return;
	if ((bp = mi->mi_tab.b_actf) == NULL) {
		mhp->mh_actf = mi->mi_forw;
		goto loop;
	}
	/*
	 * If this device isn't present and on-line, then
	 * we screwed up, and can't really do the operation.
	 */
	if ((mi->mi_drv->mbd_ds & (MBD_DPR|MBD_MOL)) != (MBD_DPR|MBD_MOL)) {
		printf("%c%d not ready\n", mi->mi_name, dkunit(bp));
		mi->mi_tab.b_actf = bp->av_forw;
		mi->mi_tab.b_errcnt = 0;
		mi->mi_tab.b_active = 0;
		bp->b_flags |= B_ERROR;
		iodone(bp);
		goto loop;
	}
	/*
	 * We can do the operation; mark the massbus active
	 * and let the device start routine setup any necessary
	 * device state for the transfer (e.g. desired cylinder, etc
	 * on disks).
	 */
	mhp->mh_active = 1;
	if (mi->mi_driver->md_start)
		(*mi->mi_driver->md_start)(mi);

	/*
	 * Setup the massbus control and map registers and start
	 * the transfer.
	 */
	mbp = mi->mi_mba;
	mbp->mba_sr = -1;	/* conservative */
	mbp->mba_var = mbasetup(mi);
	mbp->mba_bcr = -bp->b_bcount;
	mi->mi_drv->mbd_cs1 =
	    (bp->b_flags & B_READ) ? MBD_RCOM|MBD_GO : MBD_WCOM|MBD_GO;
	if (mi->mi_dk >= 0) {
		dk_busy |= 1 << mi->mi_dk;
		dk_xfer[mi->mi_dk]++;
		dk_wds[mi->mi_dk] += bp->b_bcount >> 6;
	}
}

/*
 * Take an interrupt off of massbus mbanum,
 * and dispatch to drivers as appropriate.
 */
mbintr(mbanum)
	int mbanum;
{
	register struct mba_hd *mhp = &mba_hd[mbanum];
	register struct mba_regs *mbp = mhp->mh_mba;
	register struct mba_info *mi;
	register struct buf *bp;
	register int drive;
	int mbastat, as;
	
	/*
	 * Read out the massbus status register
	 * and attention status register and clear
	 * the bits in same by writing them back.
	 */
	mbastat = mbp->mba_sr;
	mbp->mba_sr = mbastat;
#if VAX750
	if (mbastat&MBS_CBHUNG)
		panic("mba CBHUNG");
#endif
	/* note: the mbd_as register is shared between drives */
	as = mbp->mba_drv[0].mbd_as;
	mbp->mba_drv[0].mbd_as = as;

	/*
	 * Disable interrupts from the massbus adapter
	 * for the duration of the operation of the massbus
	 * driver, so that spurious interrupts won't be generated.
	 */
	mbp->mba_cr &= ~MBAIE;

	/*
	 * If the mba was active, process the data transfer
	 * complete interrupt; otherwise just process units which
	 * are now finished.
	 */
	if (mhp->mh_active) {
		/*
		 * Clear attention status for drive whose data
		 * transfer completed, and give the dtint driver
		 * routine a chance to say what is next.
		 */
		mi = mhp->mh_actf;
		as &= ~(1 << mi->mi_drive);
		dk_busy &= ~(1 << mi->mi_dk);
		bp = mi->mi_tab.b_actf;
		switch((*mi->mi_driver->md_dtint)(mi, mbastat)) {

		case MBD_DONE:		/* all done, for better or worse */
			/*
			 * Flush request from drive queue.
			 */
			mi->mi_tab.b_errcnt = 0;
			mi->mi_tab.b_actf = bp->av_forw;
			iodone(bp);
			/* fall into... */
		case MBD_RETRY:		/* attempt the operation again */
			/*
			 * Dequeue data transfer from massbus queue;
			 * if there is still a i/o request on the device
			 * queue then start the next operation on the device.
			 * (Common code for DONE and RETRY).
			 */
			mhp->mh_active = 0;
			mi->mi_tab.b_active = 0;
			mhp->mh_actf = mi->mi_forw;
			if (mi->mi_tab.b_actf)
				mbustart(mi);
			break;

		case MBD_RESTARTED:	/* driver restarted op (ecc, e.g.)
			/*
			 * Note that mhp->mh_active is still on.
			 */
			break;

		default:
			panic("mbintr");
		}
	}
doattn:
	/*
	 * Service drives which require attention
	 * after non-data-transfer operations.
	 */
	for (drive = 0; as && drive < 8; drive++)
		if (as & (1 << drive)) {
			as &= ~(1 << drive);
			/*
			 * Consistency check the implied attention,
			 * to make sure the drive should have interrupted.
			 */
			mi = mhp->mh_mbip[drive];
			if (mi == NULL || mi->mi_tab.b_active == 0 &&
			    (mi->mi_tab.b_flags&B_BUSY) == 0 ||
			    (bp = mi->mi_tab.b_actf) == NULL)
				continue;		/* unsolicited */
			/*
			 * If this interrupt wasn't a notification that
			 * a dual ported drive is available, and if the
			 * driver has a handler for non-data transfer
			 * interrupts, give it a chance to tell us that
			 * the operation needs to be redone
			 */
			if (mi->mi_driver->md_ndint &&
			    (mi->mi_tab.b_flags&B_BUSY) == 0) {
				mi->mi_tab.b_active = 0;
				switch((*mi->mi_driver->md_ndint)(mi)) {

				case MBN_DONE:
					/*
					 * Non-data transfer interrupt
					 * completed i/o request's processing.
					 */
					mi->mi_tab.b_errcnt = 0;
					mi->mi_tab.b_actf = bp->av_forw;
					iodone(bp);
					/* fall into... */
				case MBN_RETRY:
					if (mi->mi_tab.b_actf)
						mbustart(mi);
					break;

				default:
					panic("mbintr");
				}
			} else
				mbustart(mi);
		}
	/*
	 * If there is an operation available and
	 * the massbus isn't active, get it going.
	 */
	if (mhp->mh_actf && !mhp->mh_active)
		mbstart(mhp);
	mbp->mba_cr |= MBAIE;
}

/*
 * Setup the mapping registers for a transfer.
 */
mbasetup(mi)
	register struct mba_info *mi;
{
	register struct mba_regs *mbap = mi->mi_mba;
	struct buf *bp = mi->mi_tab.b_actf;
	register int i;
	int npf;
	unsigned v;
	register struct pte *pte, *io;
	int o;
	int vaddr;
	struct proc *rp;

	io = mbap->mba_map;
	v = btop(bp->b_un.b_addr);
	o = (int)bp->b_un.b_addr & PGOFSET;
	npf = btoc(bp->b_bcount + o);
	rp = bp->b_flags&B_DIRTY ? &proc[2] : bp->b_proc;
	vaddr = o;
	if (bp->b_flags & B_UAREA) {
		for (i = 0; i < UPAGES; i++) {
			if (rp->p_addr[i].pg_pfnum == 0)
				panic("mba: zero upage");
			*(int *)io++ = rp->p_addr[i].pg_pfnum | PG_V;
		}
	} else if ((bp->b_flags & B_PHYS) == 0) {
		pte = &Sysmap[btop(((int)bp->b_un.b_addr)&0x7fffffff)];
		while (--npf >= 0)
			*(int *)io++ = pte++->pg_pfnum | PG_V;
	} else {
		if (bp->b_flags & B_PAGET)
			pte = &Usrptmap[btokmx((struct pte *)bp->b_un.b_addr)];
		else
			pte = vtopte(rp, v);
		while (--npf >= 0) {
			if (pte->pg_pfnum == 0)
				panic("mba, zero entry");
			*(int *)io++ = pte++->pg_pfnum | PG_V;
		}
	}
	*(int *)io++ = 0;
	return (vaddr);
}
#endif