/* Copyright (c) 2004 Coraid, Inc.  See COPYING for GPL terms. */
/*
 * aoecmd.c
 * Filesystem request handling methods
 */

#include <linux/hdreg.h>
#include <linux/blkdev.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include "aoe.h"

#define TIMERTICK (HZ / 10)
#define MINTIMER (2 * TIMERTICK)
#define MAXTIMER (HZ << 1)
#define MAXWAIT (60 * 3)        /* After MAXWAIT seconds, give up and fail dev */

static struct sk_buff *
new_skb(struct net_device *if_dev, ulong len)
{
        struct sk_buff *skb;

        skb = alloc_skb(len, GFP_ATOMIC);
        if (skb) {
                skb->nh.raw = skb->mac.raw = skb->data;
                skb->dev = if_dev;
                skb->protocol = __constant_htons(ETH_P_AOE);
                skb->priority = 0;
                skb_put(skb, len);
                skb->next = skb->prev = NULL;

                /* tell the network layer not to perform IP checksums
                 * or to get the NIC to do it
                 */
                skb->ip_summed = CHECKSUM_NONE;
        }
        return skb;
}

static struct sk_buff *
skb_prepare(struct aoedev *d, struct frame *f)
{
        struct sk_buff *skb;
        char *p;

        skb = new_skb(d->ifp, f->ndata + f->writedatalen);
        if (!skb) {
                printk(KERN_INFO "aoe: skb_prepare: failure to allocate skb\n");
                return NULL;
        }

        p = skb->mac.raw;
        memcpy(p, f->data, f->ndata);

        if (f->writedatalen) {
                p += sizeof(struct aoe_hdr) + sizeof(struct aoe_atahdr);
                memcpy(p, f->bufaddr, f->writedatalen);
        }

        return skb;
}

static struct frame *
getframe(struct aoedev *d, int tag)
{
        struct frame *f, *e;

        f = d->frames;
        e = f + d->nframes;
        for (; f<e; f++)
                if (f->tag == tag)
                        return f;
        return NULL;
}

/*
 * Leave the top bit clear so we have tagspace for userland.
 * The bottom 16 bits are the xmit tick for rexmit/rttavg processing.
 * This driver reserves tag -1 to mean "unused frame."
 */
static int
newtag(struct aoedev *d)
{
        register ulong n;

        n = jiffies & 0xffff;
        return n |= (++d->lasttag & 0x7fff) << 16;
}

static int
aoehdr_atainit(struct aoedev *d, struct aoe_hdr *h)
{
        u16 type = __constant_cpu_to_be16(ETH_P_AOE);
        u16 aoemajor = __cpu_to_be16(d->aoemajor);
        u32 host_tag = newtag(d);
        u32 tag = __cpu_to_be32(host_tag);

        memcpy(h->src, d->ifp->dev_addr, sizeof h->src);
        memcpy(h->dst, d->addr, sizeof h->dst);
        memcpy(h->type, &type, sizeof type);
        h->verfl = AOE_HVER;
        memcpy(h->major, &aoemajor, sizeof aoemajor);
        h->minor = d->aoeminor;
        h->cmd = AOECMD_ATA;
        memcpy(h->tag, &tag, sizeof tag);

        return host_tag;
}

static void
aoecmd_ata_rw(struct aoedev *d, struct frame *f)
{
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        struct buf *buf;
        struct sk_buff *skb;
        ulong bcnt;
        register sector_t sector;
        char writebit, extbit;

        writebit = 0x10;
        extbit = 0x4;

        buf = d->inprocess;

        sector = buf->sector;
        bcnt = buf->bv_resid;
        if (bcnt > MAXATADATA)
                bcnt = MAXATADATA;

        /* initialize the headers & frame */
        h = (struct aoe_hdr *) f->data;
        ah = (struct aoe_atahdr *) (h+1);
        f->ndata = sizeof *h + sizeof *ah;
        memset(h, 0, f->ndata);
        f->tag = aoehdr_atainit(d, h);
        f->waited = 0;
        f->buf = buf;
        f->bufaddr = buf->bufaddr;

        /* set up ata header */
        ah->scnt = bcnt >> 9;
        ah->lba0 = sector;
        ah->lba1 = sector >>= 8;
        ah->lba2 = sector >>= 8;
        ah->lba3 = sector >>= 8;
        if (d->flags & DEVFL_EXT) {
                ah->aflags |= AOEAFL_EXT;
                ah->lba4 = sector >>= 8;
                ah->lba5 = sector >>= 8;
        } else {
                extbit = 0;
                ah->lba3 &= 0x0f;
                ah->lba3 |= 0xe0;       /* LBA bit + obsolete 0xa0 */
        }

        if (bio_data_dir(buf->bio) == WRITE) {
                ah->aflags |= AOEAFL_WRITE;
                f->writedatalen = bcnt;
        } else {
                writebit = 0;
                f->writedatalen = 0;
        }

        ah->cmdstat = WIN_READ | writebit | extbit;

        /* mark all tracking fields and load out */
        buf->nframesout += 1;
        buf->bufaddr += bcnt;
        buf->bv_resid -= bcnt;
/* printk(KERN_INFO "aoe: bv_resid=%ld\n", buf->bv_resid); */
        buf->resid -= bcnt;
        buf->sector += bcnt >> 9;
        if (buf->resid == 0) {
                d->inprocess = NULL;
        } else if (buf->bv_resid == 0) {
                buf->bv++;
                buf->bv_resid = buf->bv->bv_len;
                buf->bufaddr = page_address(buf->bv->bv_page) + buf->bv->bv_offset;
        }

        skb = skb_prepare(d, f);
        if (skb) {
                skb->next = d->skblist;
                d->skblist = skb;
        }
}

/* enters with d->lock held */
void
aoecmd_work(struct aoedev *d)
{
        struct frame *f;
        struct buf *buf;
loop:
        f = getframe(d, FREETAG);
        if (f == NULL)
                return;
        if (d->inprocess == NULL) {
                if (list_empty(&d->bufq))
                        return;
                buf = container_of(d->bufq.next, struct buf, bufs);
                list_del(d->bufq.next);
/*printk(KERN_INFO "aoecmd_work: bi_size=%ld\n", buf->bio->bi_size); */
                d->inprocess = buf;
        }
        aoecmd_ata_rw(d, f);
        goto loop;
}

static void
rexmit(struct aoedev *d, struct frame *f)
{
        struct sk_buff *skb;
        struct aoe_hdr *h;
        char buf[128];
        u32 n;
        u32 net_tag;

        n = newtag(d);

        snprintf(buf, sizeof buf,
                "%15s e%ld.%ld oldtag=%08x@%08lx newtag=%08x\n",
                "retransmit",
                d->aoemajor, d->aoeminor, f->tag, jiffies, n);
        aoechr_error(buf);

        h = (struct aoe_hdr *) f->data;
        f->tag = n;
        net_tag = __cpu_to_be32(n);
        memcpy(h->tag, &net_tag, sizeof net_tag);

        skb = skb_prepare(d, f);
        if (skb) {
                skb->next = d->skblist;
                d->skblist = skb;
        }
}

static int
tsince(int tag)
{
        int n;

        n = jiffies & 0xffff;
        n -= tag & 0xffff;
        if (n < 0)
                n += 1<<16;
        return n;
}

static void
rexmit_timer(ulong vp)
{
        struct aoedev *d;
        struct frame *f, *e;
        struct sk_buff *sl;
        register long timeout;
        ulong flags, n;

        d = (struct aoedev *) vp;
        sl = NULL;

        /* timeout is always ~150% of the moving average */
        timeout = d->rttavg;
        timeout += timeout >> 1;

        spin_lock_irqsave(&d->lock, flags);

        if (d->flags & DEVFL_TKILL) {
tdie:           spin_unlock_irqrestore(&d->lock, flags);
                return;
        }
        f = d->frames;
        e = f + d->nframes;
        for (; f<e; f++) {
                if (f->tag != FREETAG && tsince(f->tag) >= timeout) {
                        n = f->waited += timeout;
                        n /= HZ;
                        if (n > MAXWAIT) { /* waited too long.  device failure. */
                                aoedev_downdev(d);
                                goto tdie;
                        }
                        rexmit(d, f);
                }
        }

        sl = d->skblist;
        d->skblist = NULL;
        if (sl) {
                n = d->rttavg <<= 1;
                if (n > MAXTIMER)
                        d->rttavg = MAXTIMER;
        }

        d->timer.expires = jiffies + TIMERTICK;
        add_timer(&d->timer);

        spin_unlock_irqrestore(&d->lock, flags);

        aoenet_xmit(sl);
}

static void
ataid_complete(struct aoedev *d, unsigned char *id)
{
        u64 ssize;
        u16 n;

        /* word 83: command set supported */
        n = __le16_to_cpu(*((u16 *) &id[83<<1]));

        /* word 86: command set/feature enabled */
        n |= __le16_to_cpu(*((u16 *) &id[86<<1]));

        if (n & (1<<10)) {      /* bit 10: LBA 48 */
                d->flags |= DEVFL_EXT;

                /* word 100: number lba48 sectors */
                ssize = __le64_to_cpu(*((u64 *) &id[100<<1]));

                /* set as in ide-disk.c:init_idedisk_capacity */
                d->geo.cylinders = ssize;
                d->geo.cylinders /= (255 * 63);
                d->geo.heads = 255;
                d->geo.sectors = 63;
        } else {
                d->flags &= ~DEVFL_EXT;

                /* number lba28 sectors */
                ssize = __le32_to_cpu(*((u32 *) &id[60<<1]));

                /* NOTE: obsolete in ATA 6 */
                d->geo.cylinders = __le16_to_cpu(*((u16 *) &id[54<<1]));
                d->geo.heads = __le16_to_cpu(*((u16 *) &id[55<<1]));
                d->geo.sectors = __le16_to_cpu(*((u16 *) &id[56<<1]));
        }
        d->ssize = ssize;
        d->geo.start = 0;
        if (d->gd != NULL) {
                d->gd->capacity = ssize;
                d->flags |= DEVFL_UP;
                return;
        }
        if (d->flags & DEVFL_WORKON) {
                printk(KERN_INFO "aoe: ataid_complete: can't schedule work, it's already on!  "
                        "(This really shouldn't happen).\n");
                return;
        }
        INIT_WORK(&d->work, aoeblk_gdalloc, d);
        schedule_work(&d->work);
        d->flags |= DEVFL_WORKON;
}

static void
calc_rttavg(struct aoedev *d, int rtt)
{
        register long n;

        n = rtt;
        if (n < MINTIMER)
                n = MINTIMER;
        else if (n > MAXTIMER)
                n = MAXTIMER;

        /* g == .25; cf. Congestion Avoidance and Control, Jacobson & Karels; 1988 */
        n -= d->rttavg;
        d->rttavg += n >> 2;
}

void
aoecmd_ata_rsp(struct sk_buff *skb)
{
        struct aoedev *d;
        struct aoe_hdr *hin;
        struct aoe_atahdr *ahin, *ahout;
        struct frame *f;
        struct buf *buf;
        struct sk_buff *sl;
        register long n;
        ulong flags;
        char ebuf[128];
        
        hin = (struct aoe_hdr *) skb->mac.raw;
        d = aoedev_bymac(hin->src);
        if (d == NULL) {
                snprintf(ebuf, sizeof ebuf, "aoecmd_ata_rsp: ata response "
                        "for unknown device %d.%d\n",
                         __be16_to_cpu(*((u16 *) hin->major)),
                        hin->minor);
                aoechr_error(ebuf);
                return;
        }

        spin_lock_irqsave(&d->lock, flags);

        f = getframe(d, __be32_to_cpu(*((u32 *) hin->tag)));
        if (f == NULL) {
                spin_unlock_irqrestore(&d->lock, flags);
                snprintf(ebuf, sizeof ebuf,
                        "%15s e%d.%d    tag=%08x@%08lx\n",
                        "unexpected rsp",
                        __be16_to_cpu(*((u16 *) hin->major)),
                        hin->minor,
                        __be32_to_cpu(*((u32 *) hin->tag)),
                        jiffies);
                aoechr_error(ebuf);
                return;
        }

        calc_rttavg(d, tsince(f->tag));

        ahin = (struct aoe_atahdr *) (hin+1);
        ahout = (struct aoe_atahdr *) (f->data + sizeof(struct aoe_hdr));
        buf = f->buf;

        if (ahin->cmdstat & 0xa9) {     /* these bits cleared on success */
                printk(KERN_CRIT "aoe: aoecmd_ata_rsp: ata error cmd=%2.2Xh "
                        "stat=%2.2Xh\n", ahout->cmdstat, ahin->cmdstat);
                if (buf)
                        buf->flags |= BUFFL_FAIL;
        } else {
                switch (ahout->cmdstat) {
                case WIN_READ:
                case WIN_READ_EXT:
                        n = ahout->scnt << 9;
                        if (skb->len - sizeof *hin - sizeof *ahin < n) {
                                printk(KERN_CRIT "aoe: aoecmd_ata_rsp: runt "
                                        "ata data size in read.  skb->len=%d\n",
                                        skb->len);
                                /* fail frame f?  just returning will rexmit. */
                                spin_unlock_irqrestore(&d->lock, flags);
                                return;
                        }
                        memcpy(f->bufaddr, ahin+1, n);
                case WIN_WRITE:
                case WIN_WRITE_EXT:
                        break;
                case WIN_IDENTIFY:
                        if (skb->len - sizeof *hin - sizeof *ahin < 512) {
                                printk(KERN_INFO "aoe: aoecmd_ata_rsp: runt data size "
                                        "in ataid.  skb->len=%d\n", skb->len);
                                spin_unlock_irqrestore(&d->lock, flags);
                                return;
                        }
                        ataid_complete(d, (char *) (ahin+1));
                        /* d->flags |= DEVFL_WC_UPDATE; */
                        break;
                default:
                        printk(KERN_INFO "aoe: aoecmd_ata_rsp: unrecognized "
                               "outbound ata command %2.2Xh for %d.%d\n", 
                               ahout->cmdstat,
                               __be16_to_cpu(*((u16 *) hin->major)),
                               hin->minor);
                }
        }

        if (buf) {
                buf->nframesout -= 1;
                if (buf->nframesout == 0 && buf->resid == 0) {
                        n = !(buf->flags & BUFFL_FAIL);
                        bio_endio(buf->bio, buf->bio->bi_size, 0);
                        mempool_free(buf, d->bufpool);
                }
        }

        f->buf = NULL;
        f->tag = FREETAG;

        aoecmd_work(d);

        sl = d->skblist;
        d->skblist = NULL;

        spin_unlock_irqrestore(&d->lock, flags);

        aoenet_xmit(sl);
}

void
aoecmd_cfg(ushort aoemajor, unsigned char aoeminor)
{
        struct aoe_hdr *h;
        struct aoe_cfghdr *ch;
        struct sk_buff *skb, *sl;
        struct net_device *ifp;
        u16 aoe_type = __constant_cpu_to_be16(ETH_P_AOE);
        u16 net_aoemajor = __cpu_to_be16(aoemajor);

        sl = NULL;

        read_lock(&dev_base_lock);
        for (ifp = dev_base; ifp; dev_put(ifp), ifp = ifp->next) {
                dev_hold(ifp);
                if (!is_aoe_netif(ifp))
                        continue;

                skb = new_skb(ifp, sizeof *h + sizeof *ch);
                if (skb == NULL) {
                        printk(KERN_INFO "aoe: aoecmd_cfg: skb alloc failure\n");
                        continue;
                }
                h = (struct aoe_hdr *) skb->mac.raw;
                memset(h, 0, sizeof *h + sizeof *ch);

                memset(h->dst, 0xff, sizeof h->dst);
                memcpy(h->src, ifp->dev_addr, sizeof h->src);
                memcpy(h->type, &aoe_type, sizeof aoe_type);
                h->verfl = AOE_HVER;
                memcpy(h->major, &net_aoemajor, sizeof net_aoemajor);
                h->minor = aoeminor;
                h->cmd = AOECMD_CFG;

                skb->next = sl;
                sl = skb;
        }
        read_unlock(&dev_base_lock);

        aoenet_xmit(sl);
}
 
/*
 * Since we only call this in one place (and it only prepares one frame)
 * we just return the skb.  Usually we'd chain it up to the d->skblist.
 */
static struct sk_buff *
aoecmd_ata_id(struct aoedev *d)
{
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        struct frame *f;
        struct sk_buff *skb;

        f = getframe(d, FREETAG);
        if (f == NULL) {
                printk(KERN_CRIT "aoe: aoecmd_ata_id: can't get a frame.  "
                        "This shouldn't happen.\n");
                return NULL;
        }

        /* initialize the headers & frame */
        h = (struct aoe_hdr *) f->data;
        ah = (struct aoe_atahdr *) (h+1);
        f->ndata = sizeof *h + sizeof *ah;
        memset(h, 0, f->ndata);
        f->tag = aoehdr_atainit(d, h);
        f->waited = 0;
        f->writedatalen = 0;

        /* this message initializes the device, so we reset the rttavg */
        d->rttavg = MAXTIMER;

        /* set up ata header */
        ah->scnt = 1;
        ah->cmdstat = WIN_IDENTIFY;
        ah->lba3 = 0xa0;

        skb = skb_prepare(d, f);

        /* we now want to start the rexmit tracking */
        d->flags &= ~DEVFL_TKILL;
        d->timer.data = (ulong) d;
        d->timer.function = rexmit_timer;
        d->timer.expires = jiffies + TIMERTICK;
        add_timer(&d->timer);

        return skb;
}
 
void
aoecmd_cfg_rsp(struct sk_buff *skb)
{
        struct aoedev *d;
        struct aoe_hdr *h;
        struct aoe_cfghdr *ch;
        ulong flags, bufcnt, sysminor, aoemajor;
        struct sk_buff *sl;
        enum { MAXFRAMES = 8, MAXSYSMINOR = 255 };

        h = (struct aoe_hdr *) skb->mac.raw;
        ch = (struct aoe_cfghdr *) (h+1);

        /*
         * Enough people have their dip switches set backwards to
         * warrant a loud message for this special case.
         */
        aoemajor = __be16_to_cpu(*((u16 *) h->major));
        if (aoemajor == 0xfff) {
                printk(KERN_CRIT "aoe: aoecmd_cfg_rsp: Warning: shelf "
                        "address is all ones.  Check shelf dip switches\n");
                return;
        }

        sysminor = SYSMINOR(aoemajor, h->minor);
        if (sysminor > MAXSYSMINOR) {
                printk(KERN_INFO "aoe: aoecmd_cfg_rsp: sysminor %ld too "
                        "large\n", sysminor);
                return;
        }

        bufcnt = __be16_to_cpu(*((u16 *) ch->bufcnt));
        if (bufcnt > MAXFRAMES) /* keep it reasonable */
                bufcnt = MAXFRAMES;

        d = aoedev_set(sysminor, h->src, skb->dev, bufcnt);
        if (d == NULL) {
                printk(KERN_INFO "aoe: aoecmd_cfg_rsp: device set failure\n");
                return;
        }

        spin_lock_irqsave(&d->lock, flags);

        if (d->flags & (DEVFL_UP | DEVFL_CLOSEWAIT)) {
                spin_unlock_irqrestore(&d->lock, flags);
                return;
        }

        d->fw_ver = __be16_to_cpu(*((u16 *) ch->fwver));

        /* we get here only if the device is new */
        sl = aoecmd_ata_id(d);

        spin_unlock_irqrestore(&d->lock, flags);

        aoenet_xmit(sl);
}