drivers/infiniband/hw/cxgb4/device.c

/*
 * Copyright (c) 2009-2010 Chelsio, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *	  copyright notice, this list of conditions and the following
 *	  disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *	  copyright notice, this list of conditions and the following
 *	  disclaimer in the documentation and/or other materials
 *	  provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/debugfs.h>

#include <rdma/ib_verbs.h>

#include "iw_cxgb4.h"

#define DRV_VERSION "0.1"

MODULE_AUTHOR("Steve Wise");
MODULE_DESCRIPTION("Chelsio T4 RDMA Driver");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_VERSION(DRV_VERSION);

struct uld_ctx {
	struct list_head entry;
	struct cxgb4_lld_info lldi;
	struct c4iw_dev *dev;
};

static LIST_HEAD(uld_ctx_list);
static DEFINE_MUTEX(dev_mutex);

static struct dentry *c4iw_debugfs_root;

struct c4iw_debugfs_data {
	struct c4iw_dev *devp;
	char *buf;
	int bufsize;
	int pos;
};

static int count_idrs(int id, void *p, void *data)
{
	int *countp = data;

	*countp = *countp + 1;
	return 0;
}

static ssize_t debugfs_read(struct file *file, char __user *buf, size_t count,
			    loff_t *ppos)
{
	struct c4iw_debugfs_data *d = file->private_data;

	return simple_read_from_buffer(buf, count, ppos, d->buf, d->pos);
}

static int dump_qp(int id, void *p, void *data)
{
	struct c4iw_qp *qp = p;
	struct c4iw_debugfs_data *qpd = data;
	int space;
	int cc;

	if (id != qp->wq.sq.qid)
		return 0;

	space = qpd->bufsize - qpd->pos - 1;
	if (space == 0)
		return 1;

	if (qp->ep)
		cc = snprintf(qpd->buf + qpd->pos, space,
			     "qp sq id %u rq id %u state %u onchip %u "
			     "ep tid %u state %u %pI4:%u->%pI4:%u\n",
			     qp->wq.sq.qid, qp->wq.rq.qid, (int)qp->attr.state,
			     qp->wq.sq.flags & T4_SQ_ONCHIP,
			     qp->ep->hwtid, (int)qp->ep->com.state,
			     &qp->ep->com.local_addr.sin_addr.s_addr,
			     ntohs(qp->ep->com.local_addr.sin_port),
			     &qp->ep->com.remote_addr.sin_addr.s_addr,
			     ntohs(qp->ep->com.remote_addr.sin_port));
	else
		cc = snprintf(qpd->buf + qpd->pos, space,
			     "qp sq id %u rq id %u state %u onchip %u\n",
			      qp->wq.sq.qid, qp->wq.rq.qid,
			      (int)qp->attr.state,
			      qp->wq.sq.flags & T4_SQ_ONCHIP);
	if (cc < space)
		qpd->pos += cc;
	return 0;
}

static int qp_release(struct inode *inode, struct file *file)
{
	struct c4iw_debugfs_data *qpd = file->private_data;
	if (!qpd) {
		printk(KERN_INFO "%s null qpd?\n", __func__);
		return 0;
	}
	kfree(qpd->buf);
	kfree(qpd);
	return 0;
}

static int qp_open(struct inode *inode, struct file *file)
{
	struct c4iw_debugfs_data *qpd;
	int ret = 0;
	int count = 1;

	qpd = kmalloc(sizeof *qpd, GFP_KERNEL);
	if (!qpd) {
		ret = -ENOMEM;
		goto out;
	}
	qpd->devp = inode->i_private;
	qpd->pos = 0;

	spin_lock_irq(&qpd->devp->lock);
	idr_for_each(&qpd->devp->qpidr, count_idrs, &count);
	spin_unlock_irq(&qpd->devp->lock);

	qpd->bufsize = count * 128;
	qpd->buf = kmalloc(qpd->bufsize, GFP_KERNEL);
	if (!qpd->buf) {
		ret = -ENOMEM;
		goto err1;
	}

	spin_lock_irq(&qpd->devp->lock);
	idr_for_each(&qpd->devp->qpidr, dump_qp, qpd);
	spin_unlock_irq(&qpd->devp->lock);

	qpd->buf[qpd->pos++] = 0;
	file->private_data = qpd;
	goto out;
err1:
	kfree(qpd);
out:
	return ret;
}

static const struct file_operations qp_debugfs_fops = {
	.owner   = THIS_MODULE,
	.open    = qp_open,
	.release = qp_release,
	.read    = debugfs_read,
	.llseek  = default_llseek,
};

static int dump_stag(int id, void *p, void *data)
{
	struct c4iw_debugfs_data *stagd = data;
	int space;
	int cc;

	space = stagd->bufsize - stagd->pos - 1;
	if (space == 0)
		return 1;

	cc = snprintf(stagd->buf + stagd->pos, space, "0x%x\n", id<<8);
	if (cc < space)
		stagd->pos += cc;
	return 0;
}

static int stag_release(struct inode *inode, struct file *file)
{
	struct c4iw_debugfs_data *stagd = file->private_data;
	if (!stagd) {
		printk(KERN_INFO "%s null stagd?\n", __func__);
		return 0;
	}
	kfree(stagd->buf);
	kfree(stagd);
	return 0;
}

static int stag_open(struct inode *inode, struct file *file)
{
	struct c4iw_debugfs_data *stagd;
	int ret = 0;
	int count = 1;

	stagd = kmalloc(sizeof *stagd, GFP_KERNEL);
	if (!stagd) {
		ret = -ENOMEM;
		goto out;
	}
	stagd->devp = inode->i_private;
	stagd->pos = 0;

	spin_lock_irq(&stagd->devp->lock);
	idr_for_each(&stagd->devp->mmidr, count_idrs, &count);
	spin_unlock_irq(&stagd->devp->lock);

	stagd->bufsize = count * sizeof("0x12345678\n");
	stagd->buf = kmalloc(stagd->bufsize, GFP_KERNEL);
	if (!stagd->buf) {
		ret = -ENOMEM;
		goto err1;
	}

	spin_lock_irq(&stagd->devp->lock);
	idr_for_each(&stagd->devp->mmidr, dump_stag, stagd);
	spin_unlock_irq(&stagd->devp->lock);

	stagd->buf[stagd->pos++] = 0;
	file->private_data = stagd;
	goto out;
err1:
	kfree(stagd);
out:
	return ret;
}

static const struct file_operations stag_debugfs_fops = {
	.owner   = THIS_MODULE,
	.open    = stag_open,
	.release = stag_release,
	.read    = debugfs_read,
	.llseek  = default_llseek,
};

static char *db_state_str[] = {"NORMAL", "FLOW_CONTROL", "RECOVERY"};

static int stats_show(struct seq_file *seq, void *v)
{
	struct c4iw_dev *dev = seq->private;

	seq_printf(seq, " Object: %10s %10s %10s\n", "Total", "Current", "Max");
	seq_printf(seq, "     PDID: %10llu %10llu %10llu\n",
			dev->rdev.stats.pd.total, dev->rdev.stats.pd.cur,
			dev->rdev.stats.pd.max);
	seq_printf(seq, "      QID: %10llu %10llu %10llu\n",
			dev->rdev.stats.qid.total, dev->rdev.stats.qid.cur,
			dev->rdev.stats.qid.max);
	seq_printf(seq, "   TPTMEM: %10llu %10llu %10llu\n",
			dev->rdev.stats.stag.total, dev->rdev.stats.stag.cur,
			dev->rdev.stats.stag.max);
	seq_printf(seq, "   PBLMEM: %10llu %10llu %10llu\n",
			dev->rdev.stats.pbl.total, dev->rdev.stats.pbl.cur,
			dev->rdev.stats.pbl.max);
	seq_printf(seq, "   RQTMEM: %10llu %10llu %10llu\n",
			dev->rdev.stats.rqt.total, dev->rdev.stats.rqt.cur,
			dev->rdev.stats.rqt.max);
	seq_printf(seq, "  OCQPMEM: %10llu %10llu %10llu\n",
			dev->rdev.stats.ocqp.total, dev->rdev.stats.ocqp.cur,
			dev->rdev.stats.ocqp.max);
	seq_printf(seq, "  DB FULL: %10llu\n", dev->rdev.stats.db_full);
	seq_printf(seq, " DB EMPTY: %10llu\n", dev->rdev.stats.db_empty);
	seq_printf(seq, "  DB DROP: %10llu\n", dev->rdev.stats.db_drop);
	seq_printf(seq, " DB State: %s Transitions %llu\n",
		   db_state_str[dev->db_state],
		   dev->rdev.stats.db_state_transitions);
	return 0;
}

static int stats_open(struct inode *inode, struct file *file)
{
	return single_open(file, stats_show, inode->i_private);
}

static ssize_t stats_clear(struct file *file, const char __user *buf,
		size_t count, loff_t *pos)
{
	struct c4iw_dev *dev = ((struct seq_file *)file->private_data)->private;

	mutex_lock(&dev->rdev.stats.lock);
	dev->rdev.stats.pd.max = 0;
	dev->rdev.stats.qid.max = 0;
	dev->rdev.stats.stag.max = 0;
	dev->rdev.stats.pbl.max = 0;
	dev->rdev.stats.rqt.max = 0;
	dev->rdev.stats.ocqp.max = 0;
	dev->rdev.stats.db_full = 0;
	dev->rdev.stats.db_empty = 0;
	dev->rdev.stats.db_drop = 0;
	dev->rdev.stats.db_state_transitions = 0;
	mutex_unlock(&dev->rdev.stats.lock);
	return count;
}

static const struct file_operations stats_debugfs_fops = {
	.owner   = THIS_MODULE,
	.open    = stats_open,
	.release = single_release,
	.read    = seq_read,
	.llseek  = seq_lseek,
	.write   = stats_clear,
};

static int setup_debugfs(struct c4iw_dev *devp)
{
	struct dentry *de;

	if (!devp->debugfs_root)
		return -1;

	de = debugfs_create_file("qps", S_IWUSR, devp->debugfs_root,
				 (void *)devp, &qp_debugfs_fops);
	if (de && de->d_inode)
		de->d_inode->i_size = 4096;

	de = debugfs_create_file("stags", S_IWUSR, devp->debugfs_root,
				 (void *)devp, &stag_debugfs_fops);
	if (de && de->d_inode)
		de->d_inode->i_size = 4096;

	de = debugfs_create_file("stats", S_IWUSR, devp->debugfs_root,
			(void *)devp, &stats_debugfs_fops);
	if (de && de->d_inode)
		de->d_inode->i_size = 4096;

	return 0;
}

void c4iw_release_dev_ucontext(struct c4iw_rdev *rdev,
			       struct c4iw_dev_ucontext *uctx)
{
	struct list_head *pos, *nxt;
	struct c4iw_qid_list *entry;

	mutex_lock(&uctx->lock);
	list_for_each_safe(pos, nxt, &uctx->qpids) {
		entry = list_entry(pos, struct c4iw_qid_list, entry);
		list_del_init(&entry->entry);
		if (!(entry->qid & rdev->qpmask)) {
			c4iw_put_resource(&rdev->resource.qid_fifo, entry->qid,
					&rdev->resource.qid_fifo_lock);
			mutex_lock(&rdev->stats.lock);
			rdev->stats.qid.cur -= rdev->qpmask + 1;
			mutex_unlock(&rdev->stats.lock);
		}
		kfree(entry);
	}

	list_for_each_safe(pos, nxt, &uctx->qpids) {
		entry = list_entry(pos, struct c4iw_qid_list, entry);
		list_del_init(&entry->entry);
		kfree(entry);
	}
	mutex_unlock(&uctx->lock);
}

void c4iw_init_dev_ucontext(struct c4iw_rdev *rdev,
			    struct c4iw_dev_ucontext *uctx)
{
	INIT_LIST_HEAD(&uctx->qpids);
	INIT_LIST_HEAD(&uctx->cqids);
	mutex_init(&uctx->lock);
}

/* Caller takes care of locking if needed */
static int c4iw_rdev_open(struct c4iw_rdev *rdev)
{
	int err;

	c4iw_init_dev_ucontext(rdev, &rdev->uctx);

	/*
	 * qpshift is the number of bits to shift the qpid left in order
	 * to get the correct address of the doorbell for that qp.
	 */
	rdev->qpshift = PAGE_SHIFT - ilog2(rdev->lldi.udb_density);
	rdev->qpmask = rdev->lldi.udb_density - 1;
	rdev->cqshift = PAGE_SHIFT - ilog2(rdev->lldi.ucq_density);
	rdev->cqmask = rdev->lldi.ucq_density - 1;
	PDBG("%s dev %s stag start 0x%0x size 0x%0x num stags %d "
	     "pbl start 0x%0x size 0x%0x rq start 0x%0x size 0x%0x "
	     "qp qid start %u size %u cq qid start %u size %u\n",
	     __func__, pci_name(rdev->lldi.pdev), rdev->lldi.vr->stag.start,
	     rdev->lldi.vr->stag.size, c4iw_num_stags(rdev),
	     rdev->lldi.vr->pbl.start,
	     rdev->lldi.vr->pbl.size, rdev->lldi.vr->rq.start,
	     rdev->lldi.vr->rq.size,
	     rdev->lldi.vr->qp.start,
	     rdev->lldi.vr->qp.size,
	     rdev->lldi.vr->cq.start,
	     rdev->lldi.vr->cq.size);
	PDBG("udb len 0x%x udb base %p db_reg %p gts_reg %p qpshift %lu "
	     "qpmask 0x%x cqshift %lu cqmask 0x%x\n",
	     (unsigned)pci_resource_len(rdev->lldi.pdev, 2),
	     (void *)pci_resource_start(rdev->lldi.pdev, 2),
	     rdev->lldi.db_reg,
	     rdev->lldi.gts_reg,
	     rdev->qpshift, rdev->qpmask,
	     rdev->cqshift, rdev->cqmask);

	if (c4iw_num_stags(rdev) == 0) {
		err = -EINVAL;
		goto err1;
	}

	rdev->stats.pd.total = T4_MAX_NUM_PD;
	rdev->stats.stag.total = rdev->lldi.vr->stag.size;
	rdev->stats.pbl.total = rdev->lldi.vr->pbl.size;
	rdev->stats.rqt.total = rdev->lldi.vr->rq.size;
	rdev->stats.ocqp.total = rdev->lldi.vr->ocq.size;
	rdev->stats.qid.total = rdev->lldi.vr->qp.size;

	err = c4iw_init_resource(rdev, c4iw_num_stags(rdev), T4_MAX_NUM_PD);
	if (err) {
		printk(KERN_ERR MOD "error %d initializing resources\n", err);
		goto err1;
	}
	err = c4iw_pblpool_create(rdev);
	if (err) {
		printk(KERN_ERR MOD "error %d initializing pbl pool\n", err);
		goto err2;
	}
	err = c4iw_rqtpool_create(rdev);
	if (err) {
		printk(KERN_ERR MOD "error %d initializing rqt pool\n", err);
		goto err3;
	}
	err = c4iw_ocqp_pool_create(rdev);
	if (err) {
		printk(KERN_ERR MOD "error %d initializing ocqp pool\n", err);
		goto err4;
	}
	return 0;
err4:
	c4iw_rqtpool_destroy(rdev);
err3:
	c4iw_pblpool_destroy(rdev);
err2:
	c4iw_destroy_resource(&rdev->resource);
err1:
	return err;
}

static void c4iw_rdev_close(struct c4iw_rdev *rdev)
{
	c4iw_pblpool_destroy(rdev);
	c4iw_rqtpool_destroy(rdev);
	c4iw_destroy_resource(&rdev->resource);
}

static void c4iw_dealloc(struct uld_ctx *ctx)
{
	c4iw_rdev_close(&ctx->dev->rdev);
	idr_destroy(&ctx->dev->cqidr);
	idr_destroy(&ctx->dev->qpidr);
	idr_destroy(&ctx->dev->mmidr);
	iounmap(ctx->dev->rdev.oc_mw_kva);
	ib_dealloc_device(&ctx->dev->ibdev);
	ctx->dev = NULL;
}

static void c4iw_remove(struct uld_ctx *ctx)
{
	PDBG("%s c4iw_dev %p\n", __func__,  ctx->dev);
	c4iw_unregister_device(ctx->dev);
	c4iw_dealloc(ctx);
}

static int rdma_supported(const struct cxgb4_lld_info *infop)
{
	return infop->vr->stag.size > 0 && infop->vr->pbl.size > 0 &&
	       infop->vr->rq.size > 0 && infop->vr->qp.size > 0 &&
	       infop->vr->cq.size > 0 && infop->vr->ocq.size > 0;
}

static struct c4iw_dev *c4iw_alloc(const struct cxgb4_lld_info *infop)
{
	struct c4iw_dev *devp;
	int ret;

	if (!rdma_supported(infop)) {
		printk(KERN_INFO MOD "%s: RDMA not supported on this device.\n",
		       pci_name(infop->pdev));
		return ERR_PTR(-ENOSYS);
	}
	devp = (struct c4iw_dev *)ib_alloc_device(sizeof(*devp));
	if (!devp) {
		printk(KERN_ERR MOD "Cannot allocate ib device\n");
		return ERR_PTR(-ENOMEM);
	}
	devp->rdev.lldi = *infop;

	devp->rdev.oc_mw_pa = pci_resource_start(devp->rdev.lldi.pdev, 2) +
		(pci_resource_len(devp->rdev.lldi.pdev, 2) -
		 roundup_pow_of_two(devp->rdev.lldi.vr->ocq.size));
	devp->rdev.oc_mw_kva = ioremap_wc(devp->rdev.oc_mw_pa,
					       devp->rdev.lldi.vr->ocq.size);

	PDBG(KERN_INFO MOD "ocq memory: "
	       "hw_start 0x%x size %u mw_pa 0x%lx mw_kva %p\n",
	       devp->rdev.lldi.vr->ocq.start, devp->rdev.lldi.vr->ocq.size,
	       devp->rdev.oc_mw_pa, devp->rdev.oc_mw_kva);

	ret = c4iw_rdev_open(&devp->rdev);
	if (ret) {
		printk(KERN_ERR MOD "Unable to open CXIO rdev err %d\n", ret);
		ib_dealloc_device(&devp->ibdev);
		return ERR_PTR(ret);
	}

	idr_init(&devp->cqidr);
	idr_init(&devp->qpidr);
	idr_init(&devp->mmidr);
	spin_lock_init(&devp->lock);
	mutex_init(&devp->rdev.stats.lock);
	mutex_init(&devp->db_mutex);

	if (c4iw_debugfs_root) {
		devp->debugfs_root = debugfs_create_dir(
					pci_name(devp->rdev.lldi.pdev),
					c4iw_debugfs_root);
		setup_debugfs(devp);
	}
	return devp;
}

static void *c4iw_uld_add(const struct cxgb4_lld_info *infop)
{
	struct uld_ctx *ctx;
	static int vers_printed;
	int i;

	if (!vers_printed++)
		printk(KERN_INFO MOD "Chelsio T4 RDMA Driver - version %s\n",
		       DRV_VERSION);

	ctx = kzalloc(sizeof *ctx, GFP_KERNEL);
	if (!ctx) {
		ctx = ERR_PTR(-ENOMEM);
		goto out;
	}
	ctx->lldi = *infop;

	PDBG("%s found device %s nchan %u nrxq %u ntxq %u nports %u\n",
	     __func__, pci_name(ctx->lldi.pdev),
	     ctx->lldi.nchan, ctx->lldi.nrxq,
	     ctx->lldi.ntxq, ctx->lldi.nports);

	mutex_lock(&dev_mutex);
	list_add_tail(&ctx->entry, &uld_ctx_list);
	mutex_unlock(&dev_mutex);

	for (i = 0; i < ctx->lldi.nrxq; i++)
		PDBG("rxqid[%u] %u\n", i, ctx->lldi.rxq_ids[i]);
out:
	return ctx;
}

static int c4iw_uld_rx_handler(void *handle, const __be64 *rsp,
			const struct pkt_gl *gl)
{
	struct uld_ctx *ctx = handle;
	struct c4iw_dev *dev = ctx->dev;
	struct sk_buff *skb;
	const struct cpl_act_establish *rpl;
	unsigned int opcode;

	if (gl == NULL) {
		/* omit RSS and rsp_ctrl at end of descriptor */
		unsigned int len = 64 - sizeof(struct rsp_ctrl) - 8;

		skb = alloc_skb(256, GFP_ATOMIC);
		if (!skb)
			goto nomem;
		__skb_put(skb, len);
		skb_copy_to_linear_data(skb, &rsp[1], len);
	} else if (gl == CXGB4_MSG_AN) {
		const struct rsp_ctrl *rc = (void *)rsp;

		u32 qid = be32_to_cpu(rc->pldbuflen_qid);
		c4iw_ev_handler(dev, qid);
		return 0;
	} else {
		skb = cxgb4_pktgl_to_skb(gl, 128, 128);
		if (unlikely(!skb))
			goto nomem;
	}

	rpl = cplhdr(skb);
	opcode = rpl->ot.opcode;

	if (c4iw_handlers[opcode])
		c4iw_handlers[opcode](dev, skb);
	else
		printk(KERN_INFO "%s no handler opcode 0x%x...\n", __func__,
		       opcode);

	return 0;
nomem:
	return -1;
}

static int c4iw_uld_state_change(void *handle, enum cxgb4_state new_state)
{
	struct uld_ctx *ctx = handle;

	PDBG("%s new_state %u\n", __func__, new_state);
	switch (new_state) {
	case CXGB4_STATE_UP:
		printk(KERN_INFO MOD "%s: Up\n", pci_name(ctx->lldi.pdev));
		if (!ctx->dev) {
			int ret;

			ctx->dev = c4iw_alloc(&ctx->lldi);
			if (IS_ERR(ctx->dev)) {
				printk(KERN_ERR MOD
				       "%s: initialization failed: %ld\n",
				       pci_name(ctx->lldi.pdev),
				       PTR_ERR(ctx->dev));
				ctx->dev = NULL;
				break;
			}
			ret = c4iw_register_device(ctx->dev);
			if (ret) {
				printk(KERN_ERR MOD
				       "%s: RDMA registration failed: %d\n",
				       pci_name(ctx->lldi.pdev), ret);
				c4iw_dealloc(ctx);
			}
		}
		break;
	case CXGB4_STATE_DOWN:
		printk(KERN_INFO MOD "%s: Down\n",
		       pci_name(ctx->lldi.pdev));
		if (ctx->dev)
			c4iw_remove(ctx);
		break;
	case CXGB4_STATE_START_RECOVERY:
		printk(KERN_INFO MOD "%s: Fatal Error\n",
		       pci_name(ctx->lldi.pdev));
		if (ctx->dev) {
			struct ib_event event;

			ctx->dev->rdev.flags |= T4_FATAL_ERROR;
			memset(&event, 0, sizeof event);
			event.event  = IB_EVENT_DEVICE_FATAL;
			event.device = &ctx->dev->ibdev;
			ib_dispatch_event(&event);
			c4iw_remove(ctx);
		}
		break;
	case CXGB4_STATE_DETACH:
		printk(KERN_INFO MOD "%s: Detach\n",
		       pci_name(ctx->lldi.pdev));
		if (ctx->dev)
			c4iw_remove(ctx);
		break;
	}
	return 0;
}

static int disable_qp_db(int id, void *p, void *data)
{
	struct c4iw_qp *qp = p;

	t4_disable_wq_db(&qp->wq);
	return 0;
}

static void stop_queues(struct uld_ctx *ctx)
{
	spin_lock_irq(&ctx->dev->lock);
	if (ctx->dev->db_state == NORMAL) {
		ctx->dev->rdev.stats.db_state_transitions++;
		ctx->dev->db_state = FLOW_CONTROL;
		idr_for_each(&ctx->dev->qpidr, disable_qp_db, NULL);
	}
	spin_unlock_irq(&ctx->dev->lock);
}

static int enable_qp_db(int id, void *p, void *data)
{
	struct c4iw_qp *qp = p;

	t4_enable_wq_db(&qp->wq);
	return 0;
}

static void resume_queues(struct uld_ctx *ctx)
{
	spin_lock_irq(&ctx->dev->lock);
	if (ctx->dev->qpcnt <= db_fc_threshold &&
	    ctx->dev->db_state == FLOW_CONTROL) {
		ctx->dev->db_state = NORMAL;
		ctx->dev->rdev.stats.db_state_transitions++;
		idr_for_each(&ctx->dev->qpidr, enable_qp_db, NULL);
	}
	spin_unlock_irq(&ctx->dev->lock);
}

struct qp_list {
	unsigned idx;
	struct c4iw_qp **qps;
};

static int add_and_ref_qp(int id, void *p, void *data)
{
	struct qp_list *qp_listp = data;
	struct c4iw_qp *qp = p;

	c4iw_qp_add_ref(&qp->ibqp);
	qp_listp->qps[qp_listp->idx++] = qp;
	return 0;
}

static int count_qps(int id, void *p, void *data)
{
	unsigned *countp = data;
	(*countp)++;
	return 0;
}

static void deref_qps(struct qp_list qp_list)
{
	int idx;

	for (idx = 0; idx < qp_list.idx; idx++)
		c4iw_qp_rem_ref(&qp_list.qps[idx]->ibqp);
}

static void recover_lost_dbs(struct uld_ctx *ctx, struct qp_list *qp_list)
{
	int idx;
	int ret;

	for (idx = 0; idx < qp_list->idx; idx++) {
		struct c4iw_qp *qp = qp_list->qps[idx];

		ret = cxgb4_sync_txq_pidx(qp->rhp->rdev.lldi.ports[0],
					  qp->wq.sq.qid,
					  t4_sq_host_wq_pidx(&qp->wq),
					  t4_sq_wq_size(&qp->wq));
		if (ret) {
			printk(KERN_ERR MOD "%s: Fatal error - "
			       "DB overflow recovery failed - "
			       "error syncing SQ qid %u\n",
			       pci_name(ctx->lldi.pdev), qp->wq.sq.qid);
			return;
		}

		ret = cxgb4_sync_txq_pidx(qp->rhp->rdev.lldi.ports[0],
					  qp->wq.rq.qid,
					  t4_rq_host_wq_pidx(&qp->wq),
					  t4_rq_wq_size(&qp->wq));

		if (ret) {
			printk(KERN_ERR MOD "%s: Fatal error - "
			       "DB overflow recovery failed - "
			       "error syncing RQ qid %u\n",
			       pci_name(ctx->lldi.pdev), qp->wq.rq.qid);
			return;
		}

		/* Wait for the dbfifo to drain */
		while (cxgb4_dbfifo_count(qp->rhp->rdev.lldi.ports[0], 1) > 0) {
			set_current_state(TASK_UNINTERRUPTIBLE);
			schedule_timeout(usecs_to_jiffies(10));
		}
	}
}

static void recover_queues(struct uld_ctx *ctx)
{
	int count = 0;
	struct qp_list qp_list;
	int ret;

	/* lock out kernel db ringers */
	mutex_lock(&ctx->dev->db_mutex);

	/* put all queues in to recovery mode */
	spin_lock_irq(&ctx->dev->lock);
	ctx->dev->db_state = RECOVERY;
	ctx->dev->rdev.stats.db_state_transitions++;
	idr_for_each(&ctx->dev->qpidr, disable_qp_db, NULL);
	spin_unlock_irq(&ctx->dev->lock);

	/* slow everybody down */
	set_current_state(TASK_UNINTERRUPTIBLE);
	schedule_timeout(usecs_to_jiffies(1000));

	/* Wait for the dbfifo to completely drain. */
	while (cxgb4_dbfifo_count(ctx->dev->rdev.lldi.ports[0], 1) > 0) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		schedule_timeout(usecs_to_jiffies(10));
	}

	/* flush the SGE contexts */
	ret = cxgb4_flush_eq_cache(ctx->dev->rdev.lldi.ports[0]);
	if (ret) {
		printk(KERN_ERR MOD "%s: Fatal error - DB overflow recovery failed\n",
		       pci_name(ctx->lldi.pdev));
		goto out;
	}

	/* Count active queues so we can build a list of queues to recover */
	spin_lock_irq(&ctx->dev->lock);
	idr_for_each(&ctx->dev->qpidr, count_qps, &count);

	qp_list.qps = kzalloc(count * sizeof *qp_list.qps, GFP_ATOMIC);
	if (!qp_list.qps) {
		printk(KERN_ERR MOD "%s: Fatal error - DB overflow recovery failed\n",
		       pci_name(ctx->lldi.pdev));
		spin_unlock_irq(&ctx->dev->lock);
		goto out;
	}
	qp_list.idx = 0;

	/* add and ref each qp so it doesn't get freed */
	idr_for_each(&ctx->dev->qpidr, add_and_ref_qp, &qp_list);

	spin_unlock_irq(&ctx->dev->lock);

	/* now traverse the list in a safe context to recover the db state*/
	recover_lost_dbs(ctx, &qp_list);

	/* we're almost done!  deref the qps and clean up */
	deref_qps(qp_list);
	kfree(qp_list.qps);

	/* Wait for the dbfifo to completely drain again */
	while (cxgb4_dbfifo_count(ctx->dev->rdev.lldi.ports[0], 1) > 0) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		schedule_timeout(usecs_to_jiffies(10));
	}

	/* resume the queues */
	spin_lock_irq(&ctx->dev->lock);
	if (ctx->dev->qpcnt > db_fc_threshold)
		ctx->dev->db_state = FLOW_CONTROL;
	else {
		ctx->dev->db_state = NORMAL;
		idr_for_each(&ctx->dev->qpidr, enable_qp_db, NULL);
	}
	ctx->dev->rdev.stats.db_state_transitions++;
	spin_unlock_irq(&ctx->dev->lock);

out:
	/* start up kernel db ringers again */
	mutex_unlock(&ctx->dev->db_mutex);
}

static int c4iw_uld_control(void *handle, enum cxgb4_control control, ...)
{
	struct uld_ctx *ctx = handle;

	switch (control) {
	case CXGB4_CONTROL_DB_FULL:
		stop_queues(ctx);
		mutex_lock(&ctx->dev->rdev.stats.lock);
		ctx->dev->rdev.stats.db_full++;
		mutex_unlock(&ctx->dev->rdev.stats.lock);
		break;
	case CXGB4_CONTROL_DB_EMPTY:
		resume_queues(ctx);
		mutex_lock(&ctx->dev->rdev.stats.lock);
		ctx->dev->rdev.stats.db_empty++;
		mutex_unlock(&ctx->dev->rdev.stats.lock);
		break;
	case CXGB4_CONTROL_DB_DROP:
		recover_queues(ctx);
		mutex_lock(&ctx->dev->rdev.stats.lock);
		ctx->dev->rdev.stats.db_drop++;
		mutex_unlock(&ctx->dev->rdev.stats.lock);
		break;
	default:
		printk(KERN_WARNING MOD "%s: unknown control cmd %u\n",
		       pci_name(ctx->lldi.pdev), control);
		break;
	}
	return 0;
}

static struct cxgb4_uld_info c4iw_uld_info = {
	.name = DRV_NAME,
	.add = c4iw_uld_add,
	.rx_handler = c4iw_uld_rx_handler,
	.state_change = c4iw_uld_state_change,
	.control = c4iw_uld_control,
};

static int __init c4iw_init_module(void)
{
	int err;

	err = c4iw_cm_init();
	if (err)
		return err;

	c4iw_debugfs_root = debugfs_create_dir(DRV_NAME, NULL);
	if (!c4iw_debugfs_root)
		printk(KERN_WARNING MOD
		       "could not create debugfs entry, continuing\n");

	cxgb4_register_uld(CXGB4_ULD_RDMA, &c4iw_uld_info);

	return 0;
}

static void __exit c4iw_exit_module(void)
{
	struct uld_ctx *ctx, *tmp;

	mutex_lock(&dev_mutex);
	list_for_each_entry_safe(ctx, tmp, &uld_ctx_list, entry) {
		if (ctx->dev)
			c4iw_remove(ctx);
		kfree(ctx);
	}
	mutex_unlock(&dev_mutex);
	cxgb4_unregister_uld(CXGB4_ULD_RDMA);
	c4iw_cm_term();
	debugfs_remove_recursive(c4iw_debugfs_root);
}

module_init(c4iw_init_module);
module_exit(c4iw_exit_module);