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ldc.c

/* ldc.c: Logical Domain Channel link-layer protocol driver.
 *
 * Copyright (C) 2007 David S. Miller <davem@davemloft.net>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/scatterlist.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/init.h>

#include <asm/hypervisor.h>
#include <asm/iommu.h>
#include <asm/page.h>
#include <asm/ldc.h>
#include <asm/mdesc.h>

#define DRV_MODULE_NAME       "ldc"
#define PFX DRV_MODULE_NAME   ": "
#define DRV_MODULE_VERSION    "1.0"
#define DRV_MODULE_RELDATE    "June 25, 2007"

static char version[] __devinitdata =
      DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")\n";
#define LDC_PACKET_SIZE       64

/* Packet header layout for unreliable and reliable mode frames.
 * When in RAW mode, packets are simply straight 64-byte payloads
 * with no headers.
 */
struct ldc_packet {
      u8                type;
#define LDC_CTRL        0x01
#define LDC_DATA        0x02
#define LDC_ERR               0x10

      u8                stype;
#define LDC_INFO        0x01
#define LDC_ACK               0x02
#define LDC_NACK        0x04

      u8                ctrl;
#define LDC_VERS        0x01 /* Link Version          */
#define LDC_RTS               0x02 /* Request To Send       */
#define LDC_RTR               0x03 /* Ready To Receive      */
#define LDC_RDX               0x04 /* Ready for Data eXchange     */
#define LDC_CTRL_MSK          0x0f

      u8                env;
#define LDC_LEN               0x3f
#define LDC_FRAG_MASK         0xc0
#define LDC_START       0x40
#define LDC_STOP        0x80

      u32               seqid;

      union {
            u8          u_data[LDC_PACKET_SIZE - 8];
            struct {
                  u32   pad;
                  u32   ackid;
                  u8    r_data[LDC_PACKET_SIZE - 8 - 8];
            } r;
      } u;
};

struct ldc_version {
      u16 major;
      u16 minor;
};

/* Ordered from largest major to lowest.  */
static struct ldc_version ver_arr[] = {
      { .major = 1, .minor = 0 },
};

#define LDC_DEFAULT_MTU             (4 * LDC_PACKET_SIZE)
#define LDC_DEFAULT_NUM_ENTRIES           (PAGE_SIZE / LDC_PACKET_SIZE)

struct ldc_channel;

struct ldc_mode_ops {
      int (*write)(struct ldc_channel *, const void *, unsigned int);
      int (*read)(struct ldc_channel *, void *, unsigned int);
};

static const struct ldc_mode_ops raw_ops;
static const struct ldc_mode_ops nonraw_ops;
static const struct ldc_mode_ops stream_ops;

int ldom_domaining_enabled;

struct ldc_iommu {
      /* Protects arena alloc/free.  */
      spinlock_t              lock;
      struct iommu_arena            arena;
      struct ldc_mtable_entry       *page_table;
};

struct ldc_channel {
      /* Protects all operations that depend upon channel state.  */
      spinlock_t              lock;

      unsigned long                 id;

      u8                      *mssbuf;
      u32                     mssbuf_len;
      u32                     mssbuf_off;

      struct ldc_packet       *tx_base;
      unsigned long                 tx_head;
      unsigned long                 tx_tail;
      unsigned long                 tx_num_entries;
      unsigned long                 tx_ra;

      unsigned long                 tx_acked;

      struct ldc_packet       *rx_base;
      unsigned long                 rx_head;
      unsigned long                 rx_tail;
      unsigned long                 rx_num_entries;
      unsigned long                 rx_ra;

      u32                     rcv_nxt;
      u32                     snd_nxt;

      unsigned long                 chan_state;

      struct ldc_channel_config     cfg;
      void                    *event_arg;

      const struct ldc_mode_ops     *mops;

      struct ldc_iommu        iommu;

      struct ldc_version            ver;

      u8                      hs_state;
#define LDC_HS_CLOSED               0x00
#define LDC_HS_OPEN                 0x01
#define LDC_HS_GOTVERS              0x02
#define LDC_HS_SENTRTR              0x03
#define LDC_HS_GOTRTR               0x04
#define LDC_HS_COMPLETE             0x10

      u8                      flags;
#define LDC_FLAG_ALLOCED_QUEUES           0x01
#define LDC_FLAG_REGISTERED_QUEUES  0x02
#define LDC_FLAG_REGISTERED_IRQS    0x04
#define LDC_FLAG_RESET              0x10

      u8                      mss;
      u8                      state;

#define LDC_IRQ_NAME_MAX            32
      char                    rx_irq_name[LDC_IRQ_NAME_MAX];
      char                    tx_irq_name[LDC_IRQ_NAME_MAX];

      struct hlist_head       mh_list;

      struct hlist_node       list;
};

#define ldcdbg(TYPE, f, a...) \
do {  if (lp->cfg.debug & LDC_DEBUG_##TYPE) \
            printk(KERN_INFO PFX "ID[%lu] " f, lp->id, ## a); \
} while (0)

static const char *state_to_str(u8 state)
{
      switch (state) {
      case LDC_STATE_INVALID:
            return "INVALID";
      case LDC_STATE_INIT:
            return "INIT";
      case LDC_STATE_BOUND:
            return "BOUND";
      case LDC_STATE_READY:
            return "READY";
      case LDC_STATE_CONNECTED:
            return "CONNECTED";
      default:
            return "<UNKNOWN>";
      }
}

static void ldc_set_state(struct ldc_channel *lp, u8 state)
{
      ldcdbg(STATE, "STATE (%s) --> (%s)\n",
             state_to_str(lp->state),
             state_to_str(state));

      lp->state = state;
}

static unsigned long __advance(unsigned long off, unsigned long num_entries)
{
      off += LDC_PACKET_SIZE;
      if (off == (num_entries * LDC_PACKET_SIZE))
            off = 0;

      return off;
}

static unsigned long rx_advance(struct ldc_channel *lp, unsigned long off)
{
      return __advance(off, lp->rx_num_entries);
}

static unsigned long tx_advance(struct ldc_channel *lp, unsigned long off)
{
      return __advance(off, lp->tx_num_entries);
}

static struct ldc_packet *handshake_get_tx_packet(struct ldc_channel *lp,
                                      unsigned long *new_tail)
{
      struct ldc_packet *p;
      unsigned long t;

      t = tx_advance(lp, lp->tx_tail);
      if (t == lp->tx_head)
            return NULL;

      *new_tail = t;

      p = lp->tx_base;
      return p + (lp->tx_tail / LDC_PACKET_SIZE);
}

/* When we are in reliable or stream mode, have to track the next packet
 * we haven't gotten an ACK for in the TX queue using tx_acked.  We have
 * to be careful not to stomp over the queue past that point.  During
 * the handshake, we don't have TX data packets pending in the queue
 * and that's why handshake_get_tx_packet() need not be mindful of
 * lp->tx_acked.
 */
static unsigned long head_for_data(struct ldc_channel *lp)
{
      if (lp->cfg.mode == LDC_MODE_STREAM)
            return lp->tx_acked;
      return lp->tx_head;
}

static int tx_has_space_for(struct ldc_channel *lp, unsigned int size)
{
      unsigned long limit, tail, new_tail, diff;
      unsigned int mss;

      limit = head_for_data(lp);
      tail = lp->tx_tail;
      new_tail = tx_advance(lp, tail);
      if (new_tail == limit)
            return 0;

      if (limit > new_tail)
            diff = limit - new_tail;
      else
            diff = (limit +
                  ((lp->tx_num_entries * LDC_PACKET_SIZE) - new_tail));
      diff /= LDC_PACKET_SIZE;
      mss = lp->mss;

      if (diff * mss < size)
            return 0;

      return 1;
}

static struct ldc_packet *data_get_tx_packet(struct ldc_channel *lp,
                                   unsigned long *new_tail)
{
      struct ldc_packet *p;
      unsigned long h, t;

      h = head_for_data(lp);
      t = tx_advance(lp, lp->tx_tail);
      if (t == h)
            return NULL;

      *new_tail = t;

      p = lp->tx_base;
      return p + (lp->tx_tail / LDC_PACKET_SIZE);
}

static int set_tx_tail(struct ldc_channel *lp, unsigned long tail)
{
      unsigned long orig_tail = lp->tx_tail;
      int limit = 1000;

      lp->tx_tail = tail;
      while (limit-- > 0) {
            unsigned long err;

            err = sun4v_ldc_tx_set_qtail(lp->id, tail);
            if (!err)
                  return 0;

            if (err != HV_EWOULDBLOCK) {
                  lp->tx_tail = orig_tail;
                  return -EINVAL;
            }
            udelay(1);
      }

      lp->tx_tail = orig_tail;
      return -EBUSY;
}

/* This just updates the head value in the hypervisor using
 * a polling loop with a timeout.  The caller takes care of
 * upating software state representing the head change, if any.
 */
static int __set_rx_head(struct ldc_channel *lp, unsigned long head)
{
      int limit = 1000;

      while (limit-- > 0) {
            unsigned long err;

            err = sun4v_ldc_rx_set_qhead(lp->id, head);
            if (!err)
                  return 0;

            if (err != HV_EWOULDBLOCK)
                  return -EINVAL;

            udelay(1);
      }

      return -EBUSY;
}

static int send_tx_packet(struct ldc_channel *lp,
                    struct ldc_packet *p,
                    unsigned long new_tail)
{
      BUG_ON(p != (lp->tx_base + (lp->tx_tail / LDC_PACKET_SIZE)));

      return set_tx_tail(lp, new_tail);
}

static struct ldc_packet *handshake_compose_ctrl(struct ldc_channel *lp,
                                     u8 stype, u8 ctrl,
                                     void *data, int dlen,
                                     unsigned long *new_tail)
{
      struct ldc_packet *p = handshake_get_tx_packet(lp, new_tail);

      if (p) {
            memset(p, 0, sizeof(*p));
            p->type = LDC_CTRL;
            p->stype = stype;
            p->ctrl = ctrl;
            if (data)
                  memcpy(p->u.u_data, data, dlen);
      }
      return p;
}

static int start_handshake(struct ldc_channel *lp)
{
      struct ldc_packet *p;
      struct ldc_version *ver;
      unsigned long new_tail;

      ver = &ver_arr[0];

      ldcdbg(HS, "SEND VER INFO maj[%u] min[%u]\n",
             ver->major, ver->minor);

      p = handshake_compose_ctrl(lp, LDC_INFO, LDC_VERS,
                           ver, sizeof(*ver), &new_tail);
      if (p) {
            int err = send_tx_packet(lp, p, new_tail);
            if (!err)
                  lp->flags &= ~LDC_FLAG_RESET;
            return err;
      }
      return -EBUSY;
}

static int send_version_nack(struct ldc_channel *lp,
                       u16 major, u16 minor)
{
      struct ldc_packet *p;
      struct ldc_version ver;
      unsigned long new_tail;

      ver.major = major;
      ver.minor = minor;

      p = handshake_compose_ctrl(lp, LDC_NACK, LDC_VERS,
                           &ver, sizeof(ver), &new_tail);
      if (p) {
            ldcdbg(HS, "SEND VER NACK maj[%u] min[%u]\n",
                   ver.major, ver.minor);

            return send_tx_packet(lp, p, new_tail);
      }
      return -EBUSY;
}

static int send_version_ack(struct ldc_channel *lp,
                      struct ldc_version *vp)
{
      struct ldc_packet *p;
      unsigned long new_tail;

      p = handshake_compose_ctrl(lp, LDC_ACK, LDC_VERS,
                           vp, sizeof(*vp), &new_tail);
      if (p) {
            ldcdbg(HS, "SEND VER ACK maj[%u] min[%u]\n",
                   vp->major, vp->minor);

            return send_tx_packet(lp, p, new_tail);
      }
      return -EBUSY;
}

static int send_rts(struct ldc_channel *lp)
{
      struct ldc_packet *p;
      unsigned long new_tail;

      p = handshake_compose_ctrl(lp, LDC_INFO, LDC_RTS, NULL, 0,
                           &new_tail);
      if (p) {
            p->env = lp->cfg.mode;
            p->seqid = 0;
            lp->rcv_nxt = 0;

            ldcdbg(HS, "SEND RTS env[0x%x] seqid[0x%x]\n",
                   p->env, p->seqid);

            return send_tx_packet(lp, p, new_tail);
      }
      return -EBUSY;
}

static int send_rtr(struct ldc_channel *lp)
{
      struct ldc_packet *p;
      unsigned long new_tail;

      p = handshake_compose_ctrl(lp, LDC_INFO, LDC_RTR, NULL, 0,
                           &new_tail);
      if (p) {
            p->env = lp->cfg.mode;
            p->seqid = 0;

            ldcdbg(HS, "SEND RTR env[0x%x] seqid[0x%x]\n",
                   p->env, p->seqid);

            return send_tx_packet(lp, p, new_tail);
      }
      return -EBUSY;
}

static int send_rdx(struct ldc_channel *lp)
{
      struct ldc_packet *p;
      unsigned long new_tail;

      p = handshake_compose_ctrl(lp, LDC_INFO, LDC_RDX, NULL, 0,
                           &new_tail);
      if (p) {
            p->env = 0;
            p->seqid = ++lp->snd_nxt;
            p->u.r.ackid = lp->rcv_nxt;

            ldcdbg(HS, "SEND RDX env[0x%x] seqid[0x%x] ackid[0x%x]\n",
                   p->env, p->seqid, p->u.r.ackid);

            return send_tx_packet(lp, p, new_tail);
      }
      return -EBUSY;
}

static int send_data_nack(struct ldc_channel *lp, struct ldc_packet *data_pkt)
{
      struct ldc_packet *p;
      unsigned long new_tail;
      int err;

      p = data_get_tx_packet(lp, &new_tail);
      if (!p)
            return -EBUSY;
      memset(p, 0, sizeof(*p));
      p->type = data_pkt->type;
      p->stype = LDC_NACK;
      p->ctrl = data_pkt->ctrl & LDC_CTRL_MSK;
      p->seqid = lp->snd_nxt + 1;
      p->u.r.ackid = lp->rcv_nxt;

      ldcdbg(HS, "SEND DATA NACK type[0x%x] ctl[0x%x] seq[0x%x] ack[0x%x]\n",
             p->type, p->ctrl, p->seqid, p->u.r.ackid);

      err = send_tx_packet(lp, p, new_tail);
      if (!err)
            lp->snd_nxt++;

      return err;
}

static int ldc_abort(struct ldc_channel *lp)
{
      unsigned long hv_err;

      ldcdbg(STATE, "ABORT\n");

      /* We report but do not act upon the hypervisor errors because
       * there really isn't much we can do if they fail at this point.
       */
      hv_err = sun4v_ldc_tx_qconf(lp->id, lp->tx_ra, lp->tx_num_entries);
      if (hv_err)
            printk(KERN_ERR PFX "ldc_abort: "
                   "sun4v_ldc_tx_qconf(%lx,%lx,%lx) failed, err=%lu\n",
                   lp->id, lp->tx_ra, lp->tx_num_entries, hv_err);

      hv_err = sun4v_ldc_tx_get_state(lp->id,
                              &lp->tx_head,
                              &lp->tx_tail,
                              &lp->chan_state);
      if (hv_err)
            printk(KERN_ERR PFX "ldc_abort: "
                   "sun4v_ldc_tx_get_state(%lx,...) failed, err=%lu\n",
                   lp->id, hv_err);

      hv_err = sun4v_ldc_rx_qconf(lp->id, lp->rx_ra, lp->rx_num_entries);
      if (hv_err)
            printk(KERN_ERR PFX "ldc_abort: "
                   "sun4v_ldc_rx_qconf(%lx,%lx,%lx) failed, err=%lu\n",
                   lp->id, lp->rx_ra, lp->rx_num_entries, hv_err);

      /* Refetch the RX queue state as well, because we could be invoked
       * here in the queue processing context.
       */
      hv_err = sun4v_ldc_rx_get_state(lp->id,
                              &lp->rx_head,
                              &lp->rx_tail,
                              &lp->chan_state);
      if (hv_err)
            printk(KERN_ERR PFX "ldc_abort: "
                   "sun4v_ldc_rx_get_state(%lx,...) failed, err=%lu\n",
                   lp->id, hv_err);

      return -ECONNRESET;
}

static struct ldc_version *find_by_major(u16 major)
{
      struct ldc_version *ret = NULL;
      int i;

      for (i = 0; i < ARRAY_SIZE(ver_arr); i++) {
            struct ldc_version *v = &ver_arr[i];
            if (v->major <= major) {
                  ret = v;
                  break;
            }
      }
      return ret;
}

static int process_ver_info(struct ldc_channel *lp, struct ldc_version *vp)
{
      struct ldc_version *vap;
      int err;

      ldcdbg(HS, "GOT VERSION INFO major[%x] minor[%x]\n",
             vp->major, vp->minor);

      if (lp->hs_state == LDC_HS_GOTVERS) {
            lp->hs_state = LDC_HS_OPEN;
            memset(&lp->ver, 0, sizeof(lp->ver));
      }

      vap = find_by_major(vp->major);
      if (!vap) {
            err = send_version_nack(lp, 0, 0);
      } else if (vap->major != vp->major) {
            err = send_version_nack(lp, vap->major, vap->minor);
      } else {
            struct ldc_version ver = *vp;
            if (ver.minor > vap->minor)
                  ver.minor = vap->minor;
            err = send_version_ack(lp, &ver);
            if (!err) {
                  lp->ver = ver;
                  lp->hs_state = LDC_HS_GOTVERS;
            }
      }
      if (err)
            return ldc_abort(lp);

      return 0;
}

static int process_ver_ack(struct ldc_channel *lp, struct ldc_version *vp)
{
      ldcdbg(HS, "GOT VERSION ACK major[%x] minor[%x]\n",
             vp->major, vp->minor);

      if (lp->hs_state == LDC_HS_GOTVERS) {
            if (lp->ver.major != vp->major ||
                lp->ver.minor != vp->minor)
                  return ldc_abort(lp);
      } else {
            lp->ver = *vp;
            lp->hs_state = LDC_HS_GOTVERS;
      }
      if (send_rts(lp))
            return ldc_abort(lp);
      return 0;
}

static int process_ver_nack(struct ldc_channel *lp, struct ldc_version *vp)
{
      struct ldc_version *vap;

      if ((vp->major == 0 && vp->minor == 0) ||
          !(vap = find_by_major(vp->major))) {
            return ldc_abort(lp);
      } else {
            struct ldc_packet *p;
            unsigned long new_tail;

            p = handshake_compose_ctrl(lp, LDC_INFO, LDC_VERS,
                                 vap, sizeof(*vap),
                                 &new_tail);
            if (p)
                  return send_tx_packet(lp, p, new_tail);
            else
                  return ldc_abort(lp);
      }
}

static int process_version(struct ldc_channel *lp,
                     struct ldc_packet *p)
{
      struct ldc_version *vp;

      vp = (struct ldc_version *) p->u.u_data;

      switch (p->stype) {
      case LDC_INFO:
            return process_ver_info(lp, vp);

      case LDC_ACK:
            return process_ver_ack(lp, vp);

      case LDC_NACK:
            return process_ver_nack(lp, vp);

      default:
            return ldc_abort(lp);
      }
}

static int process_rts(struct ldc_channel *lp,
                   struct ldc_packet *p)
{
      ldcdbg(HS, "GOT RTS stype[%x] seqid[%x] env[%x]\n",
             p->stype, p->seqid, p->env);

      if (p->stype     != LDC_INFO     ||
          lp->hs_state != LDC_HS_GOTVERS ||
          p->env       != lp->cfg.mode)
            return ldc_abort(lp);

      lp->snd_nxt = p->seqid;
      lp->rcv_nxt = p->seqid;
      lp->hs_state = LDC_HS_SENTRTR;
      if (send_rtr(lp))
            return ldc_abort(lp);

      return 0;
}

static int process_rtr(struct ldc_channel *lp,
                   struct ldc_packet *p)
{
      ldcdbg(HS, "GOT RTR stype[%x] seqid[%x] env[%x]\n",
             p->stype, p->seqid, p->env);

      if (p->stype     != LDC_INFO ||
          p->env       != lp->cfg.mode)
            return ldc_abort(lp);

      lp->snd_nxt = p->seqid;
      lp->hs_state = LDC_HS_COMPLETE;
      ldc_set_state(lp, LDC_STATE_CONNECTED);
      send_rdx(lp);

      return LDC_EVENT_UP;
}

static int rx_seq_ok(struct ldc_channel *lp, u32 seqid)
{
      return lp->rcv_nxt + 1 == seqid;
}

static int process_rdx(struct ldc_channel *lp,
                   struct ldc_packet *p)
{
      ldcdbg(HS, "GOT RDX stype[%x] seqid[%x] env[%x] ackid[%x]\n",
             p->stype, p->seqid, p->env, p->u.r.ackid);

      if (p->stype != LDC_INFO ||
          !(rx_seq_ok(lp, p->seqid)))
            return ldc_abort(lp);

      lp->rcv_nxt = p->seqid;

      lp->hs_state = LDC_HS_COMPLETE;
      ldc_set_state(lp, LDC_STATE_CONNECTED);

      return LDC_EVENT_UP;
}

static int process_control_frame(struct ldc_channel *lp,
                         struct ldc_packet *p)
{
      switch (p->ctrl) {
      case LDC_VERS:
            return process_version(lp, p);

      case LDC_RTS:
            return process_rts(lp, p);

      case LDC_RTR:
            return process_rtr(lp, p);

      case LDC_RDX:
            return process_rdx(lp, p);

      default:
            return ldc_abort(lp);
      }
}

static int process_error_frame(struct ldc_channel *lp,
                         struct ldc_packet *p)
{
      return ldc_abort(lp);
}

static int process_data_ack(struct ldc_channel *lp,
                      struct ldc_packet *ack)
{
      unsigned long head = lp->tx_acked;
      u32 ackid = ack->u.r.ackid;

      while (1) {
            struct ldc_packet *p = lp->tx_base + (head / LDC_PACKET_SIZE);

            head = tx_advance(lp, head);

            if (p->seqid == ackid) {
                  lp->tx_acked = head;
                  return 0;
            }
            if (head == lp->tx_tail)
                  return ldc_abort(lp);
      }

      return 0;
}

static void send_events(struct ldc_channel *lp, unsigned int event_mask)
{
      if (event_mask & LDC_EVENT_RESET)
            lp->cfg.event(lp->event_arg, LDC_EVENT_RESET);
      if (event_mask & LDC_EVENT_UP)
            lp->cfg.event(lp->event_arg, LDC_EVENT_UP);
      if (event_mask & LDC_EVENT_DATA_READY)
            lp->cfg.event(lp->event_arg, LDC_EVENT_DATA_READY);
}

static irqreturn_t ldc_rx(int irq, void *dev_id)
{
      struct ldc_channel *lp = dev_id;
      unsigned long orig_state, hv_err, flags;
      unsigned int event_mask;

      spin_lock_irqsave(&lp->lock, flags);

      orig_state = lp->chan_state;
      hv_err = sun4v_ldc_rx_get_state(lp->id,
                              &lp->rx_head,
                              &lp->rx_tail,
                              &lp->chan_state);

      ldcdbg(RX, "RX state[0x%02lx:0x%02lx] head[0x%04lx] tail[0x%04lx]\n",
             orig_state, lp->chan_state, lp->rx_head, lp->rx_tail);

      event_mask = 0;

      if (lp->cfg.mode == LDC_MODE_RAW &&
          lp->chan_state == LDC_CHANNEL_UP) {
            lp->hs_state = LDC_HS_COMPLETE;
            ldc_set_state(lp, LDC_STATE_CONNECTED);

            event_mask |= LDC_EVENT_UP;

            orig_state = lp->chan_state;
      }

      /* If we are in reset state, flush the RX queue and ignore
       * everything.
       */
      if (lp->flags & LDC_FLAG_RESET) {
            (void) __set_rx_head(lp, lp->rx_tail);
            goto out;
      }

      /* Once we finish the handshake, we let the ldc_read()
       * paths do all of the control frame and state management.
       * Just trigger the callback.
       */
      if (lp->hs_state == LDC_HS_COMPLETE) {
handshake_complete:
            if (lp->chan_state != orig_state) {
                  unsigned int event = LDC_EVENT_RESET;

                  if (lp->chan_state == LDC_CHANNEL_UP)
                        event = LDC_EVENT_UP;

                  event_mask |= event;
            }
            if (lp->rx_head != lp->rx_tail)
                  event_mask |= LDC_EVENT_DATA_READY;

            goto out;
      }

      if (lp->chan_state != orig_state)
            goto out;

      while (lp->rx_head != lp->rx_tail) {
            struct ldc_packet *p;
            unsigned long new;
            int err;

            p = lp->rx_base + (lp->rx_head / LDC_PACKET_SIZE);

            switch (p->type) {
            case LDC_CTRL:
                  err = process_control_frame(lp, p);
                  if (err > 0)
                        event_mask |= err;
                  break;

            case LDC_DATA:
                  event_mask |= LDC_EVENT_DATA_READY;
                  err = 0;
                  break;

            case LDC_ERR:
                  err = process_error_frame(lp, p);
                  break;

            default:
                  err = ldc_abort(lp);
                  break;
            }

            if (err < 0)
                  break;

            new = lp->rx_head;
            new += LDC_PACKET_SIZE;
            if (new == (lp->rx_num_entries * LDC_PACKET_SIZE))
                  new = 0;
            lp->rx_head = new;

            err = __set_rx_head(lp, new);
            if (err < 0) {
                  (void) ldc_abort(lp);
                  break;
            }
            if (lp->hs_state == LDC_HS_COMPLETE)
                  goto handshake_complete;
      }

out:
      spin_unlock_irqrestore(&lp->lock, flags);

      send_events(lp, event_mask);

      return IRQ_HANDLED;
}

static irqreturn_t ldc_tx(int irq, void *dev_id)
{
      struct ldc_channel *lp = dev_id;
      unsigned long flags, hv_err, orig_state;
      unsigned int event_mask = 0;

      spin_lock_irqsave(&lp->lock, flags);

      orig_state = lp->chan_state;
      hv_err = sun4v_ldc_tx_get_state(lp->id,
                              &lp->tx_head,
                              &lp->tx_tail,
                              &lp->chan_state);

      ldcdbg(TX, " TX state[0x%02lx:0x%02lx] head[0x%04lx] tail[0x%04lx]\n",
             orig_state, lp->chan_state, lp->tx_head, lp->tx_tail);

      if (lp->cfg.mode == LDC_MODE_RAW &&
          lp->chan_state == LDC_CHANNEL_UP) {
            lp->hs_state = LDC_HS_COMPLETE;
            ldc_set_state(lp, LDC_STATE_CONNECTED);

            event_mask |= LDC_EVENT_UP;
      }

      spin_unlock_irqrestore(&lp->lock, flags);

      send_events(lp, event_mask);

      return IRQ_HANDLED;
}

/* XXX ldc_alloc() and ldc_free() needs to run under a mutex so
 * XXX that addition and removal from the ldc_channel_list has
 * XXX atomicity, otherwise the __ldc_channel_exists() check is
 * XXX totally pointless as another thread can slip into ldc_alloc()
 * XXX and add a channel with the same ID.  There also needs to be
 * XXX a spinlock for ldc_channel_list.
 */
static HLIST_HEAD(ldc_channel_list);

static int __ldc_channel_exists(unsigned long id)
{
      struct ldc_channel *lp;
      struct hlist_node *n;

      hlist_for_each_entry(lp, n, &ldc_channel_list, list) {
            if (lp->id == id)
                  return 1;
      }
      return 0;
}

static int alloc_queue(const char *name, unsigned long num_entries,
                   struct ldc_packet **base, unsigned long *ra)
{
      unsigned long size, order;
      void *q;

      size = num_entries * LDC_PACKET_SIZE;
      order = get_order(size);

      q = (void *) __get_free_pages(GFP_KERNEL, order);
      if (!q) {
            printk(KERN_ERR PFX "Alloc of %s queue failed with "
                   "size=%lu order=%lu\n", name, size, order);
            return -ENOMEM;
      }

      memset(q, 0, PAGE_SIZE << order);

      *base = q;
      *ra = __pa(q);

      return 0;
}

static void free_queue(unsigned long num_entries, struct ldc_packet *q)
{
      unsigned long size, order;

      if (!q)
            return;

      size = num_entries * LDC_PACKET_SIZE;
      order = get_order(size);

      free_pages((unsigned long)q, order);
}

/* XXX Make this configurable... XXX */
#define LDC_IOTABLE_SIZE      (8 * 1024)

static int ldc_iommu_init(struct ldc_channel *lp)
{
      unsigned long sz, num_tsb_entries, tsbsize, order;
      struct ldc_iommu *iommu = &lp->iommu;
      struct ldc_mtable_entry *table;
      unsigned long hv_err;
      int err;

      num_tsb_entries = LDC_IOTABLE_SIZE;
      tsbsize = num_tsb_entries * sizeof(struct ldc_mtable_entry);

      spin_lock_init(&iommu->lock);

      sz = num_tsb_entries / 8;
      sz = (sz + 7UL) & ~7UL;
      iommu->arena.map = kzalloc(sz, GFP_KERNEL);
      if (!iommu->arena.map) {
            printk(KERN_ERR PFX "Alloc of arena map failed, sz=%lu\n", sz);
            return -ENOMEM;
      }

      iommu->arena.limit = num_tsb_entries;

      order = get_order(tsbsize);

      table = (struct ldc_mtable_entry *)
            __get_free_pages(GFP_KERNEL, order);
      err = -ENOMEM;
      if (!table) {
            printk(KERN_ERR PFX "Alloc of MTE table failed, "
                   "size=%lu order=%lu\n", tsbsize, order);
            goto out_free_map;
      }

      memset(table, 0, PAGE_SIZE << order);

      iommu->page_table = table;

      hv_err = sun4v_ldc_set_map_table(lp->id, __pa(table),
                               num_tsb_entries);
      err = -EINVAL;
      if (hv_err)
            goto out_free_table;

      return 0;

out_free_table:
      free_pages((unsigned long) table, order);
      iommu->page_table = NULL;

out_free_map:
      kfree(iommu->arena.map);
      iommu->arena.map = NULL;

      return err;
}

static void ldc_iommu_release(struct ldc_channel *lp)
{
      struct ldc_iommu *iommu = &lp->iommu;
      unsigned long num_tsb_entries, tsbsize, order;

      (void) sun4v_ldc_set_map_table(lp->id, 0, 0);

      num_tsb_entries = iommu->arena.limit;
      tsbsize = num_tsb_entries * sizeof(struct ldc_mtable_entry);
      order = get_order(tsbsize);

      free_pages((unsigned long) iommu->page_table, order);
      iommu->page_table = NULL;

      kfree(iommu->arena.map);
      iommu->arena.map = NULL;
}

struct ldc_channel *ldc_alloc(unsigned long id,
                        const struct ldc_channel_config *cfgp,
                        void *event_arg)
{
      struct ldc_channel *lp;
      const struct ldc_mode_ops *mops;
      unsigned long dummy1, dummy2, hv_err;
      u8 mss, *mssbuf;
      int err;

      err = -ENODEV;
      if (!ldom_domaining_enabled)
            goto out_err;

      err = -EINVAL;
      if (!cfgp)
            goto out_err;

      switch (cfgp->mode) {
      case LDC_MODE_RAW:
            mops = &raw_ops;
            mss = LDC_PACKET_SIZE;
            break;

      case LDC_MODE_UNRELIABLE:
            mops = &nonraw_ops;
            mss = LDC_PACKET_SIZE - 8;
            break;

      case LDC_MODE_STREAM:
            mops = &stream_ops;
            mss = LDC_PACKET_SIZE - 8 - 8;
            break;

      default:
            goto out_err;
      }

      if (!cfgp->event || !event_arg || !cfgp->rx_irq || !cfgp->tx_irq)
            goto out_err;

      hv_err = sun4v_ldc_tx_qinfo(id, &dummy1, &dummy2);
      err = -ENODEV;
      if (hv_err == HV_ECHANNEL)
            goto out_err;

      err = -EEXIST;
      if (__ldc_channel_exists(id))
            goto out_err;

      mssbuf = NULL;

      lp = kzalloc(sizeof(*lp), GFP_KERNEL);
      err = -ENOMEM;
      if (!lp)
            goto out_err;

      spin_lock_init(&lp->lock);

      lp->id = id;

      err = ldc_iommu_init(lp);
      if (err)
            goto out_free_ldc;

      lp->mops = mops;
      lp->mss = mss;

      lp->cfg = *cfgp;
      if (!lp->cfg.mtu)
            lp->cfg.mtu = LDC_DEFAULT_MTU;

      if (lp->cfg.mode == LDC_MODE_STREAM) {
            mssbuf = kzalloc(lp->cfg.mtu, GFP_KERNEL);
            if (!mssbuf) {
                  err = -ENOMEM;
                  goto out_free_iommu;
            }
            lp->mssbuf = mssbuf;
      }

      lp->event_arg = event_arg;

      /* XXX allow setting via ldc_channel_config to override defaults
       * XXX or use some formula based upon mtu
       */
      lp->tx_num_entries = LDC_DEFAULT_NUM_ENTRIES;
      lp->rx_num_entries = LDC_DEFAULT_NUM_ENTRIES;

      err = alloc_queue("TX", lp->tx_num_entries,
                    &lp->tx_base, &lp->tx_ra);
      if (err)
            goto out_free_mssbuf;

      err = alloc_queue("RX", lp->rx_num_entries,
                    &lp->rx_base, &lp->rx_ra);
      if (err)
            goto out_free_txq;

      lp->flags |= LDC_FLAG_ALLOCED_QUEUES;

      lp->hs_state = LDC_HS_CLOSED;
      ldc_set_state(lp, LDC_STATE_INIT);

      INIT_HLIST_NODE(&lp->list);
      hlist_add_head(&lp->list, &ldc_channel_list);

      INIT_HLIST_HEAD(&lp->mh_list);

      return lp;

out_free_txq:
      free_queue(lp->tx_num_entries, lp->tx_base);

out_free_mssbuf:
      if (mssbuf)
            kfree(mssbuf);

out_free_iommu:
      ldc_iommu_release(lp);

out_free_ldc:
      kfree(lp);

out_err:
      return ERR_PTR(err);
}
EXPORT_SYMBOL(ldc_alloc);

void ldc_free(struct ldc_channel *lp)
{
      if (lp->flags & LDC_FLAG_REGISTERED_IRQS) {
            free_irq(lp->cfg.rx_irq, lp);
            free_irq(lp->cfg.tx_irq, lp);
      }

      if (lp->flags & LDC_FLAG_REGISTERED_QUEUES) {
            sun4v_ldc_tx_qconf(lp->id, 0, 0);
            sun4v_ldc_rx_qconf(lp->id, 0, 0);
            lp->flags &= ~LDC_FLAG_REGISTERED_QUEUES;
      }
      if (lp->flags & LDC_FLAG_ALLOCED_QUEUES) {
            free_queue(lp->tx_num_entries, lp->tx_base);
            free_queue(lp->rx_num_entries, lp->rx_base);
            lp->flags &= ~LDC_FLAG_ALLOCED_QUEUES;
      }

      hlist_del(&lp->list);

      if (lp->mssbuf)
            kfree(lp->mssbuf);

      ldc_iommu_release(lp);

      kfree(lp);
}
EXPORT_SYMBOL(ldc_free);

/* Bind the channel.  This registers the LDC queues with
 * the hypervisor and puts the channel into a pseudo-listening
 * state.  This does not initiate a handshake, ldc_connect() does
 * that.
 */
int ldc_bind(struct ldc_channel *lp, const char *name)
{
      unsigned long hv_err, flags;
      int err = -EINVAL;

      spin_lock_irqsave(&lp->lock, flags);

      if (!name)
            goto out_err;

      if (lp->state != LDC_STATE_INIT)
            goto out_err;

      snprintf(lp->rx_irq_name, LDC_IRQ_NAME_MAX, "%s RX", name);
      snprintf(lp->tx_irq_name, LDC_IRQ_NAME_MAX, "%s TX", name);

      err = request_irq(lp->cfg.rx_irq, ldc_rx,
                    IRQF_SAMPLE_RANDOM | IRQF_SHARED,
                    lp->rx_irq_name, lp);
      if (err)
            goto out_err;

      err = request_irq(lp->cfg.tx_irq, ldc_tx,
                    IRQF_SAMPLE_RANDOM | IRQF_SHARED,
                    lp->tx_irq_name, lp);
      if (err)
            goto out_free_rx_irq;


      lp->flags |= LDC_FLAG_REGISTERED_IRQS;

      err = -ENODEV;
      hv_err = sun4v_ldc_tx_qconf(lp->id, 0, 0);
      if (hv_err)
            goto out_free_tx_irq;

      hv_err = sun4v_ldc_tx_qconf(lp->id, lp->tx_ra, lp->tx_num_entries);
      if (hv_err)
            goto out_free_tx_irq;

      hv_err = sun4v_ldc_rx_qconf(lp->id, 0, 0);
      if (hv_err)
            goto out_unmap_tx;

      hv_err = sun4v_ldc_rx_qconf(lp->id, lp->rx_ra, lp->rx_num_entries);
      if (hv_err)
            goto out_unmap_tx;

      lp->flags |= LDC_FLAG_REGISTERED_QUEUES;

      hv_err = sun4v_ldc_tx_get_state(lp->id,
                              &lp->tx_head,
                              &lp->tx_tail,
                              &lp->chan_state);
      err = -EBUSY;
      if (hv_err)
            goto out_unmap_rx;

      lp->tx_acked = lp->tx_head;

      lp->hs_state = LDC_HS_OPEN;
      ldc_set_state(lp, LDC_STATE_BOUND);

      spin_unlock_irqrestore(&lp->lock, flags);

      return 0;

out_unmap_rx:
      lp->flags &= ~LDC_FLAG_REGISTERED_QUEUES;
      sun4v_ldc_rx_qconf(lp->id, 0, 0);

out_unmap_tx:
      sun4v_ldc_tx_qconf(lp->id, 0, 0);

out_free_tx_irq:
      lp->flags &= ~LDC_FLAG_REGISTERED_IRQS;
      free_irq(lp->cfg.tx_irq, lp);

out_free_rx_irq:
      free_irq(lp->cfg.rx_irq, lp);

out_err:
      spin_unlock_irqrestore(&lp->lock, flags);

      return err;
}
EXPORT_SYMBOL(ldc_bind);

int ldc_connect(struct ldc_channel *lp)
{
      unsigned long flags;
      int err;

      if (lp->cfg.mode == LDC_MODE_RAW)
            return -EINVAL;

      spin_lock_irqsave(&lp->lock, flags);

      if (!(lp->flags & LDC_FLAG_ALLOCED_QUEUES) ||
          !(lp->flags & LDC_FLAG_REGISTERED_QUEUES) ||
          lp->hs_state != LDC_HS_OPEN)
            err = -EINVAL;
      else
            err = start_handshake(lp);

      spin_unlock_irqrestore(&lp->lock, flags);

      return err;
}
EXPORT_SYMBOL(ldc_connect);

int ldc_disconnect(struct ldc_channel *lp)
{
      unsigned long hv_err, flags;
      int err;

      if (lp->cfg.mode == LDC_MODE_RAW)
            return -EINVAL;

      if (!(lp->flags & LDC_FLAG_ALLOCED_QUEUES) ||
          !(lp->flags & LDC_FLAG_REGISTERED_QUEUES))
            return -EINVAL;

      spin_lock_irqsave(&lp->lock, flags);

      err = -ENODEV;
      hv_err = sun4v_ldc_tx_qconf(lp->id, 0, 0);
      if (hv_err)
            goto out_err;

      hv_err = sun4v_ldc_tx_qconf(lp->id, lp->tx_ra, lp->tx_num_entries);
      if (hv_err)
            goto out_err;

      hv_err = sun4v_ldc_rx_qconf(lp->id, 0, 0);
      if (hv_err)
            goto out_err;

      hv_err = sun4v_ldc_rx_qconf(lp->id, lp->rx_ra, lp->rx_num_entries);
      if (hv_err)
            goto out_err;

      ldc_set_state(lp, LDC_STATE_BOUND);
      lp->hs_state = LDC_HS_OPEN;
      lp->flags |= LDC_FLAG_RESET;

      spin_unlock_irqrestore(&lp->lock, flags);

      return 0;

out_err:
      sun4v_ldc_tx_qconf(lp->id, 0, 0);
      sun4v_ldc_rx_qconf(lp->id, 0, 0);
      free_irq(lp->cfg.tx_irq, lp);
      free_irq(lp->cfg.rx_irq, lp);
      lp->flags &= ~(LDC_FLAG_REGISTERED_IRQS |
                   LDC_FLAG_REGISTERED_QUEUES);
      ldc_set_state(lp, LDC_STATE_INIT);

      spin_unlock_irqrestore(&lp->lock, flags);

      return err;
}
EXPORT_SYMBOL(ldc_disconnect);

int ldc_state(struct ldc_channel *lp)
{
      return lp->state;
}
EXPORT_SYMBOL(ldc_state);

static int write_raw(struct ldc_channel *lp, const void *buf, unsigned int size)
{
      struct ldc_packet *p;
      unsigned long new_tail;
      int err;

      if (size > LDC_PACKET_SIZE)
            return -EMSGSIZE;

      p = data_get_tx_packet(lp, &new_tail);
      if (!p)
            return -EAGAIN;

      memcpy(p, buf, size);

      err = send_tx_packet(lp, p, new_tail);
      if (!err)
            err = size;

      return err;
}

static int read_raw(struct ldc_channel *lp, void *buf, unsigned int size)
{
      struct ldc_packet *p;
      unsigned long hv_err, new;
      int err;

      if (size < LDC_PACKET_SIZE)
            return -EINVAL;

      hv_err = sun4v_ldc_rx_get_state(lp->id,
                              &lp->rx_head,
                              &lp->rx_tail,
                              &lp->chan_state);
      if (hv_err)
            return ldc_abort(lp);

      if (lp->chan_state == LDC_CHANNEL_DOWN ||
          lp->chan_state == LDC_CHANNEL_RESETTING)
            return -ECONNRESET;

      if (lp->rx_head == lp->rx_tail)
            return 0;

      p = lp->rx_base + (lp->rx_head / LDC_PACKET_SIZE);
      memcpy(buf, p, LDC_PACKET_SIZE);

      new = rx_advance(lp, lp->rx_head);
      lp->rx_head = new;

      err = __set_rx_head(lp, new);
      if (err < 0)
            err = -ECONNRESET;
      else
            err = LDC_PACKET_SIZE;

      return err;
}

static const struct ldc_mode_ops raw_ops = {
      .write            =     write_raw,
      .read       =     read_raw,
};

static int write_nonraw(struct ldc_channel *lp, const void *buf,
                  unsigned int size)
{
      unsigned long hv_err, tail;
      unsigned int copied;
      u32 seq;
      int err;

      hv_err = sun4v_ldc_tx_get_state(lp->id, &lp->tx_head, &lp->tx_tail,
                              &lp->chan_state);
      if (unlikely(hv_err))
            return -EBUSY;

      if (unlikely(lp->chan_state != LDC_CHANNEL_UP))
            return ldc_abort(lp);

      if (!tx_has_space_for(lp, size))
            return -EAGAIN;

      seq = lp->snd_nxt;
      copied = 0;
      tail = lp->tx_tail;
      while (copied < size) {
            struct ldc_packet *p = lp->tx_base + (tail / LDC_PACKET_SIZE);
            u8 *data = ((lp->cfg.mode == LDC_MODE_UNRELIABLE) ?
                      p->u.u_data :
                      p->u.r.r_data);
            int data_len;

            p->type = LDC_DATA;
            p->stype = LDC_INFO;
            p->ctrl = 0;

            data_len = size - copied;
            if (data_len > lp->mss)
                  data_len = lp->mss;

            BUG_ON(data_len > LDC_LEN);

            p->env = (data_len |
                    (copied == 0 ? LDC_START : 0) |
                    (data_len == size - copied ? LDC_STOP : 0));

            p->seqid = ++seq;

            ldcdbg(DATA, "SENT DATA [%02x:%02x:%02x:%02x:%08x]\n",
                   p->type,
                   p->stype,
                   p->ctrl,
                   p->env,
                   p->seqid);

            memcpy(data, buf, data_len);
            buf += data_len;
            copied += data_len;

            tail = tx_advance(lp, tail);
      }

      err = set_tx_tail(lp, tail);
      if (!err) {
            lp->snd_nxt = seq;
            err = size;
      }

      return err;
}

static int rx_bad_seq(struct ldc_channel *lp, struct ldc_packet *p,
                  struct ldc_packet *first_frag)
{
      int err;

      if (first_frag)
            lp->rcv_nxt = first_frag->seqid - 1;

      err = send_data_nack(lp, p);
      if (err)
            return err;

      err = __set_rx_head(lp, lp->rx_tail);
      if (err < 0)
            return ldc_abort(lp);

      return 0;
}

static int data_ack_nack(struct ldc_channel *lp, struct ldc_packet *p)
{
      if (p->stype & LDC_ACK) {
            int err = process_data_ack(lp, p);
            if (err)
                  return err;
      }
      if (p->stype & LDC_NACK)
            return ldc_abort(lp);

      return 0;
}

static int rx_data_wait(struct ldc_channel *lp, unsigned long cur_head)
{
      unsigned long dummy;
      int limit = 1000;

      ldcdbg(DATA, "DATA WAIT cur_head[%lx] rx_head[%lx] rx_tail[%lx]\n",
             cur_head, lp->rx_head, lp->rx_tail);
      while (limit-- > 0) {
            unsigned long hv_err;

            hv_err = sun4v_ldc_rx_get_state(lp->id,
                                    &dummy,
                                    &lp->rx_tail,
                                    &lp->chan_state);
            if (hv_err)
                  return ldc_abort(lp);

            if (lp->chan_state == LDC_CHANNEL_DOWN ||
                lp->chan_state == LDC_CHANNEL_RESETTING)
                  return -ECONNRESET;

            if (cur_head != lp->rx_tail) {
                  ldcdbg(DATA, "DATA WAIT DONE "
                         "head[%lx] tail[%lx] chan_state[%lx]\n",
                         dummy, lp->rx_tail, lp->chan_state);
                  return 0;
            }

            udelay(1);
      }
      return -EAGAIN;
}

static int rx_set_head(struct ldc_channel *lp, unsigned long head)
{
      int err = __set_rx_head(lp, head);

      if (err < 0)
            return ldc_abort(lp);

      lp->rx_head = head;
      return 0;
}

static void send_data_ack(struct ldc_channel *lp)
{
      unsigned long new_tail;
      struct ldc_packet *p;

      p = data_get_tx_packet(lp, &new_tail);
      if (likely(p)) {
            int err;

            memset(p, 0, sizeof(*p));
            p->type = LDC_DATA;
            p->stype = LDC_ACK;
            p->ctrl = 0;
            p->seqid = lp->snd_nxt + 1;
            p->u.r.ackid = lp->rcv_nxt;

            err = send_tx_packet(lp, p, new_tail);
            if (!err)
                  lp->snd_nxt++;
      }
}

static int read_nonraw(struct ldc_channel *lp, void *buf, unsigned int size)
{
      struct ldc_packet *first_frag;
      unsigned long hv_err, new;
      int err, copied;

      hv_err = sun4v_ldc_rx_get_state(lp->id,
                              &lp->rx_head,
                              &lp->rx_tail,
                              &lp->chan_state);
      if (hv_err)
            return ldc_abort(lp);

      if (lp->chan_state == LDC_CHANNEL_DOWN ||
          lp->chan_state == LDC_CHANNEL_RESETTING)
            return -ECONNRESET;

      if (lp->rx_head == lp->rx_tail)
            return 0;

      first_frag = NULL;
      copied = err = 0;
      new = lp->rx_head;
      while (1) {
            struct ldc_packet *p;
            int pkt_len;

            BUG_ON(new == lp->rx_tail);
            p = lp->rx_base + (new / LDC_PACKET_SIZE);

            ldcdbg(RX, "RX read pkt[%02x:%02x:%02x:%02x:%08x:%08x] "
                   "rcv_nxt[%08x]\n",
                   p->type,
                   p->stype,
                   p->ctrl,
                   p->env,
                   p->seqid,
                   p->u.r.ackid,
                   lp->rcv_nxt);

            if (unlikely(!rx_seq_ok(lp, p->seqid))) {
                  err = rx_bad_seq(lp, p, first_frag);
                  copied = 0;
                  break;
            }

            if (p->type & LDC_CTRL) {
                  err = process_control_frame(lp, p);
                  if (err < 0)
                        break;
                  err = 0;
            }

            lp->rcv_nxt = p->seqid;

            if (!(p->type & LDC_DATA)) {
                  new = rx_advance(lp, new);
                  goto no_data;
            }
            if (p->stype & (LDC_ACK | LDC_NACK)) {
                  err = data_ack_nack(lp, p);
                  if (err)
                        break;
            }
            if (!(p->stype & LDC_INFO)) {
                  new = rx_advance(lp, new);
                  err = rx_set_head(lp, new);
                  if (err)
                        break;
                  goto no_data;
            }

            pkt_len = p->env & LDC_LEN;

            /* Every initial packet starts with the START bit set.
             *
             * Singleton packets will have both START+STOP set.
             *
             * Fragments will have START set in the first frame, STOP
             * set in the last frame, and neither bit set in middle
             * frames of the packet.
             *
             * Therefore if we are at the beginning of a packet and
             * we don't see START, or we are in the middle of a fragmented
             * packet and do see START, we are unsynchronized and should
             * flush the RX queue.
             */
            if ((first_frag == NULL && !(p->env & LDC_START)) ||
                (first_frag != NULL &&  (p->env & LDC_START))) {
                  if (!first_frag)
                        new = rx_advance(lp, new);

                  err = rx_set_head(lp, new);
                  if (err)
                        break;

                  if (!first_frag)
                        goto no_data;
            }
            if (!first_frag)
                  first_frag = p;

            if (pkt_len > size - copied) {
                  /* User didn't give us a big enough buffer,
                   * what to do?  This is a pretty serious error.
                   *
                   * Since we haven't updated the RX ring head to
                   * consume any of the packets, signal the error
                   * to the user and just leave the RX ring alone.
                   *
                   * This seems the best behavior because this allows
                   * a user of the LDC layer to start with a small
                   * RX buffer for ldc_read() calls and use -EMSGSIZE
                   * as a cue to enlarge it's read buffer.
                   */
                  err = -EMSGSIZE;
                  break;
            }

            /* Ok, we are gonna eat this one.  */
            new = rx_advance(lp, new);

            memcpy(buf,
                   (lp->cfg.mode == LDC_MODE_UNRELIABLE ?
                  p->u.u_data : p->u.r.r_data), pkt_len);
            buf += pkt_len;
            copied += pkt_len;

            if (p->env & LDC_STOP)
                  break;

no_data:
            if (new == lp->rx_tail) {
                  err = rx_data_wait(lp, new);
                  if (err)
                        break;
            }
      }

      if (!err)
            err = rx_set_head(lp, new);

      if (err && first_frag)
            lp->rcv_nxt = first_frag->seqid - 1;

      if (!err) {
            err = copied;
            if (err > 0 && lp->cfg.mode != LDC_MODE_UNRELIABLE)
                  send_data_ack(lp);
      }

      return err;
}

static const struct ldc_mode_ops nonraw_ops = {
      .write            =     write_nonraw,
      .read       =     read_nonraw,
};

static int write_stream(struct ldc_channel *lp, const void *buf,
                  unsigned int size)
{
      if (size > lp->cfg.mtu)
            size = lp->cfg.mtu;
      return write_nonraw(lp, buf, size);
}

static int read_stream(struct ldc_channel *lp, void *buf, unsigned int size)
{
      if (!lp->mssbuf_len) {
            int err = read_nonraw(lp, lp->mssbuf, lp->cfg.mtu);
            if (err < 0)
                  return err;

            lp->mssbuf_len = err;
            lp->mssbuf_off = 0;
      }

      if (size > lp->mssbuf_len)
            size = lp->mssbuf_len;
      memcpy(buf, lp->mssbuf + lp->mssbuf_off, size);

      lp->mssbuf_off += size;
      lp->mssbuf_len -= size;

      return size;
}

static const struct ldc_mode_ops stream_ops = {
      .write            =     write_stream,
      .read       =     read_stream,
};

int ldc_write(struct ldc_channel *lp, const void *buf, unsigned int size)
{
      unsigned long flags;
      int err;

      if (!buf)
            return -EINVAL;

      if (!size)
            return 0;

      spin_lock_irqsave(&lp->lock, flags);

      if (lp->hs_state != LDC_HS_COMPLETE)
            err = -ENOTCONN;
      else
            err = lp->mops->write(lp, buf, size);

      spin_unlock_irqrestore(&lp->lock, flags);

      return err;
}
EXPORT_SYMBOL(ldc_write);

int ldc_read(struct ldc_channel *lp, void *buf, unsigned int size)
{
      unsigned long flags;
      int err;

      if (!buf)
            return -EINVAL;

      if (!size)
            return 0;

      spin_lock_irqsave(&lp->lock, flags);

      if (lp->hs_state != LDC_HS_COMPLETE)
            err = -ENOTCONN;
      else
            err = lp->mops->read(lp, buf, size);

      spin_unlock_irqrestore(&lp->lock, flags);

      return err;
}
EXPORT_SYMBOL(ldc_read);

static long arena_alloc(struct ldc_iommu *iommu, unsigned long npages)
{
      struct iommu_arena *arena = &iommu->arena;
      unsigned long n, i, start, end, limit;
      int pass;

      limit = arena->limit;
      start = arena->hint;
      pass = 0;

again:
      n = find_next_zero_bit(arena->map, limit, start);
      end = n + npages;
      if (unlikely(end >= limit)) {
            if (likely(pass < 1)) {
                  limit = start;
                  start = 0;
                  pass++;
                  goto again;
            } else {
                  /* Scanned the whole thing, give up. */
                  return -1;
            }
      }

      for (i = n; i < end; i++) {
            if (test_bit(i, arena->map)) {
                  start = i + 1;
                  goto again;
            }
      }

      for (i = n; i < end; i++)
            __set_bit(i, arena->map);

      arena->hint = end;

      return n;
}

#define COOKIE_PGSZ_CODE      0xf000000000000000ULL
#define COOKIE_PGSZ_CODE_SHIFT      60ULL

static u64 pagesize_code(void)
{
      switch (PAGE_SIZE) {
      default:
      case (8ULL * 1024ULL):
            return 0;
      case (64ULL * 1024ULL):
            return 1;
      case (512ULL * 1024ULL):
            return 2;
      case (4ULL * 1024ULL * 1024ULL):
            return 3;
      case (32ULL * 1024ULL * 1024ULL):
            return 4;
      case (256ULL * 1024ULL * 1024ULL):
            return 5;
      }
}

static u64 make_cookie(u64 index, u64 pgsz_code, u64 page_offset)
{
      return ((pgsz_code << COOKIE_PGSZ_CODE_SHIFT) |
            (index << PAGE_SHIFT) |
            page_offset);
}

static u64 cookie_to_index(u64 cookie, unsigned long *shift)
{
      u64 szcode = cookie >> COOKIE_PGSZ_CODE_SHIFT;

      cookie &= ~COOKIE_PGSZ_CODE;

      *shift = szcode * 3;

      return (cookie >> (13ULL + (szcode * 3ULL)));
}

static struct ldc_mtable_entry *alloc_npages(struct ldc_iommu *iommu,
                                   unsigned long npages)
{
      long entry;

      entry = arena_alloc(iommu, npages);
      if (unlikely(entry < 0))
            return NULL;

      return iommu->page_table + entry;
}

static u64 perm_to_mte(unsigned int map_perm)
{
      u64 mte_base;

      mte_base = pagesize_code();

      if (map_perm & LDC_MAP_SHADOW) {
            if (map_perm & LDC_MAP_R)
                  mte_base |= LDC_MTE_COPY_R;
            if (map_perm & LDC_MAP_W)
                  mte_base |= LDC_MTE_COPY_W;
      }
      if (map_perm & LDC_MAP_DIRECT) {
            if (map_perm & LDC_MAP_R)
                  mte_base |= LDC_MTE_READ;
            if (map_perm & LDC_MAP_W)
                  mte_base |= LDC_MTE_WRITE;
            if (map_perm & LDC_MAP_X)
                  mte_base |= LDC_MTE_EXEC;
      }
      if (map_perm & LDC_MAP_IO) {
            if (map_perm & LDC_MAP_R)
                  mte_base |= LDC_MTE_IOMMU_R;
            if (map_perm & LDC_MAP_W)
                  mte_base |= LDC_MTE_IOMMU_W;
      }

      return mte_base;
}

static int pages_in_region(unsigned long base, long len)
{
      int count = 0;

      do {
            unsigned long new = (base + PAGE_SIZE) & PAGE_MASK;

            len -= (new - base);
            base = new;
            count++;
      } while (len > 0);

      return count;
}

struct cookie_state {
      struct ldc_mtable_entry       *page_table;
      struct ldc_trans_cookie       *cookies;
      u64                     mte_base;
      u64                     prev_cookie;
      u32                     pte_idx;
      u32                     nc;
};

static void fill_cookies(struct cookie_state *sp, unsigned long pa,
                   unsigned long off, unsigned long len)
{
      do {
            unsigned long tlen, new = pa + PAGE_SIZE;
            u64 this_cookie;

            sp->page_table[sp->pte_idx].mte = sp->mte_base | pa;

            tlen = PAGE_SIZE;
            if (off)
                  tlen = PAGE_SIZE - off;
            if (tlen > len)
                  tlen = len;

            this_cookie = make_cookie(sp->pte_idx,
                                pagesize_code(), off);

            off = 0;

            if (this_cookie == sp->prev_cookie) {
                  sp->cookies[sp->nc - 1].cookie_size += tlen;
            } else {
                  sp->cookies[sp->nc].cookie_addr = this_cookie;
                  sp->cookies[sp->nc].cookie_size = tlen;
                  sp->nc++;
            }
            sp->prev_cookie = this_cookie + tlen;

            sp->pte_idx++;

            len -= tlen;
            pa = new;
      } while (len > 0);
}

static int sg_count_one(struct scatterlist *sg)
{
      unsigned long base = page_to_pfn(sg_page(sg)) << PAGE_SHIFT;
      long len = sg->length;

      if ((sg->offset | len) & (8UL - 1))
            return -EFAULT;

      return pages_in_region(base + sg->offset, len);
}

static int sg_count_pages(struct scatterlist *sg, int num_sg)
{
      int count;
      int i;

      count = 0;
      for (i = 0; i < num_sg; i++) {
            int err = sg_count_one(sg + i);
            if (err < 0)
                  return err;
            count += err;
      }

      return count;
}

int ldc_map_sg(struct ldc_channel *lp,
             struct scatterlist *sg, int num_sg,
             struct ldc_trans_cookie *cookies, int ncookies,
             unsigned int map_perm)
{
      unsigned long i, npages, flags;
      struct ldc_mtable_entry *base;
      struct cookie_state state;
      struct ldc_iommu *iommu;
      int err;

      if (map_perm & ~LDC_MAP_ALL)
            return -EINVAL;

      err = sg_count_pages(sg, num_sg);
      if (err < 0)
            return err;

      npages = err;
      if (err > ncookies)
            return -EMSGSIZE;

      iommu = &lp->iommu;

      spin_lock_irqsave(&iommu->lock, flags);
      base = alloc_npages(iommu, npages);
      spin_unlock_irqrestore(&iommu->lock, flags);

      if (!base)
            return -ENOMEM;

      state.page_table = iommu->page_table;
      state.cookies = cookies;
      state.mte_base = perm_to_mte(map_perm);
      state.prev_cookie = ~(u64)0;
      state.pte_idx = (base - iommu->page_table);
      state.nc = 0;

      for (i = 0; i < num_sg; i++)
            fill_cookies(&state, page_to_pfn(sg_page(&sg[i])) << PAGE_SHIFT,
                       sg[i].offset, sg[i].length);

      return state.nc;
}
EXPORT_SYMBOL(ldc_map_sg);

int ldc_map_single(struct ldc_channel *lp,
               void *buf, unsigned int len,
               struct ldc_trans_cookie *cookies, int ncookies,
               unsigned int map_perm)
{
      unsigned long npages, pa, flags;
      struct ldc_mtable_entry *base;
      struct cookie_state state;
      struct ldc_iommu *iommu;

      if ((map_perm & ~LDC_MAP_ALL) || (ncookies < 1))
            return -EINVAL;

      pa = __pa(buf);
      if ((pa | len) & (8UL - 1))
            return -EFAULT;

      npages = pages_in_region(pa, len);

      iommu = &lp->iommu;

      spin_lock_irqsave(&iommu->lock, flags);
      base = alloc_npages(iommu, npages);
      spin_unlock_irqrestore(&iommu->lock, flags);

      if (!base)
            return -ENOMEM;

      state.page_table = iommu->page_table;
      state.cookies = cookies;
      state.mte_base = perm_to_mte(map_perm);
      state.prev_cookie = ~(u64)0;
      state.pte_idx = (base - iommu->page_table);
      state.nc = 0;
      fill_cookies(&state, (pa & PAGE_MASK), (pa & ~PAGE_MASK), len);
      BUG_ON(state.nc != 1);

      return state.nc;
}
EXPORT_SYMBOL(ldc_map_single);

static void free_npages(unsigned long id, struct ldc_iommu *iommu,
                  u64 cookie, u64 size)
{
      struct iommu_arena *arena = &iommu->arena;
      unsigned long i, shift, index, npages;
      struct ldc_mtable_entry *base;

      npages = PAGE_ALIGN(((cookie & ~PAGE_MASK) + size)) >> PAGE_SHIFT;
      index = cookie_to_index(cookie, &shift);
      base = iommu->page_table + index;

      BUG_ON(index > arena->limit ||
             (index + npages) > arena->limit);

      for (i = 0; i < npages; i++) {
            if (base->cookie)
                  sun4v_ldc_revoke(id, cookie + (i << shift),
                               base->cookie);
            base->mte = 0;
            __clear_bit(index + i, arena->map);
      }
}

void ldc_unmap(struct ldc_channel *lp, struct ldc_trans_cookie *cookies,
             int ncookies)
{
      struct ldc_iommu *iommu = &lp->iommu;
      unsigned long flags;
      int i;

      spin_lock_irqsave(&iommu->lock, flags);
      for (i = 0; i < ncookies; i++) {
            u64 addr = cookies[i].cookie_addr;
            u64 size = cookies[i].cookie_size;

            free_npages(lp->id, iommu, addr, size);
      }
      spin_unlock_irqrestore(&iommu->lock, flags);
}
EXPORT_SYMBOL(ldc_unmap);

int ldc_copy(struct ldc_channel *lp, int copy_dir,
           void *buf, unsigned int len, unsigned long offset,
           struct ldc_trans_cookie *cookies, int ncookies)
{
      unsigned int orig_len;
      unsigned long ra;
      int i;

      if (copy_dir != LDC_COPY_IN && copy_dir != LDC_COPY_OUT) {
            printk(KERN_ERR PFX "ldc_copy: ID[%lu] Bad copy_dir[%d]\n",
                   lp->id, copy_dir);
            return -EINVAL;
      }

      ra = __pa(buf);
      if ((ra | len | offset) & (8UL - 1)) {
            printk(KERN_ERR PFX "ldc_copy: ID[%lu] Unaligned buffer "
                   "ra[%lx] len[%x] offset[%lx]\n",
                   lp->id, ra, len, offset);
            return -EFAULT;
      }

      if (lp->hs_state != LDC_HS_COMPLETE ||
          (lp->flags & LDC_FLAG_RESET)) {
            printk(KERN_ERR PFX "ldc_copy: ID[%lu] Link down hs_state[%x] "
                   "flags[%x]\n", lp->id, lp->hs_state, lp->flags);
            return -ECONNRESET;
      }

      orig_len = len;
      for (i = 0; i < ncookies; i++) {
            unsigned long cookie_raddr = cookies[i].cookie_addr;
            unsigned long this_len = cookies[i].cookie_size;
            unsigned long actual_len;

            if (unlikely(offset)) {
                  unsigned long this_off = offset;

                  if (this_off > this_len)
                        this_off = this_len;

                  offset -= this_off;
                  this_len -= this_off;
                  if (!this_len)
                        continue;
                  cookie_raddr += this_off;
            }

            if (this_len > len)
                  this_len = len;

            while (1) {
                  unsigned long hv_err;

                  hv_err = sun4v_ldc_copy(lp->id, copy_dir,
                                    cookie_raddr, ra,
                                    this_len, &actual_len);
                  if (unlikely(hv_err)) {
                        printk(KERN_ERR PFX "ldc_copy: ID[%lu] "
                               "HV error %lu\n",
                               lp->id, hv_err);
                        if (lp->hs_state != LDC_HS_COMPLETE ||
                            (lp->flags & LDC_FLAG_RESET))
                              return -ECONNRESET;
                        else
                              return -EFAULT;
                  }

                  cookie_raddr += actual_len;
                  ra += actual_len;
                  len -= actual_len;
                  if (actual_len == this_len)
                        break;

                  this_len -= actual_len;
            }

            if (!len)
                  break;
      }

      /* It is caller policy what to do about short copies.
       * For example, a networking driver can declare the
       * packet a runt and drop it.
       */

      return orig_len - len;
}
EXPORT_SYMBOL(ldc_copy);

void *ldc_alloc_exp_dring(struct ldc_channel *lp, unsigned int len,
                    struct ldc_trans_cookie *cookies, int *ncookies,
                    unsigned int map_perm)
{
      void *buf;
      int err;

      if (len & (8UL - 1))
            return ERR_PTR(-EINVAL);

      buf = kzalloc(len, GFP_KERNEL);
      if (!buf)
            return ERR_PTR(-ENOMEM);

      err = ldc_map_single(lp, buf, len, cookies, *ncookies, map_perm);
      if (err < 0) {
            kfree(buf);
            return ERR_PTR(err);
      }
      *ncookies = err;

      return buf;
}
EXPORT_SYMBOL(ldc_alloc_exp_dring);

void ldc_free_exp_dring(struct ldc_channel *lp, void *buf, unsigned int len,
                  struct ldc_trans_cookie *cookies, int ncookies)
{
      ldc_unmap(lp, cookies, ncookies);
      kfree(buf);
}
EXPORT_SYMBOL(ldc_free_exp_dring);

static int __init ldc_init(void)
{
      unsigned long major, minor;
      struct mdesc_handle *hp;
      const u64 *v;
      int err;
      u64 mp;

      hp = mdesc_grab();
      if (!hp)
            return -ENODEV;

      mp = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
      err = -ENODEV;
      if (mp == MDESC_NODE_NULL)
            goto out;

      v = mdesc_get_property(hp, mp, "domaining-enabled", NULL);
      if (!v)
            goto out;

      major = 1;
      minor = 0;
      if (sun4v_hvapi_register(HV_GRP_LDOM, major, &minor)) {
            printk(KERN_INFO PFX "Could not register LDOM hvapi.\n");
            goto out;
      }

      printk(KERN_INFO "%s", version);

      if (!*v) {
            printk(KERN_INFO PFX "Domaining disabled.\n");
            goto out;
      }
      ldom_domaining_enabled = 1;
      err = 0;

out:
      mdesc_release(hp);
      return err;
}

core_initcall(ldc_init);

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