rapidio/tsi721: add check for overlapped IB window mappings

Add check for attempts to request mapping of inbound RapidIO address
space that overlaps with existing active mapping windows.

Tsi721 device does not support overlapped inbound windows and SRIO
address decoding behavior is not defined in such cases.

This patch is applicable to kernel versions starting from v3.7.

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rapidio/devices/tsi721.c b/drivers/rapidio/devices/tsi721.c
index f57ee9d..b96f0b9 100644
--- a/drivers/rapidio/devices/tsi721.c
+++ b/drivers/rapidio/devices/tsi721.c
@@ -885,26 +885,52 @@
 		u64 rstart, u32 size, u32 flags)
 {
 	struct tsi721_device *priv = mport->priv;
-	int i;
+	int i, avail = -1;
 	u32 regval;
+	struct tsi721_ib_win *ib_win;
+	int ret = -EBUSY;
 
 	if (!is_power_of_2(size) || size < 0x1000 ||
 	    ((u64)lstart & (size - 1)) || (rstart & (size - 1)))
 		return -EINVAL;
 
-	/* Search for free inbound translation window */
+	spin_lock(&priv->win_lock);
+	/*
+	 * Scan for overlapping with active regions and mark the first available
+	 * IB window at the same time.
+	 */
 	for (i = 0; i < TSI721_IBWIN_NUM; i++) {
-		regval = ioread32(priv->regs + TSI721_IBWIN_LB(i));
-		if (!(regval & TSI721_IBWIN_LB_WEN))
+		ib_win = &priv->ib_win[i];
+		if (!ib_win->active) {
+			if (avail == -1) {
+				avail = i;
+				ret = 0;
+			}
+		} else if (rstart < (ib_win->rstart + ib_win->size) &&
+					(rstart + size) > ib_win->rstart) {
+			ret = -EFAULT;
 			break;
+		}
 	}
 
-	if (i >= TSI721_IBWIN_NUM) {
-		dev_err(&priv->pdev->dev,
-			"Unable to find free inbound window\n");
-		return -EBUSY;
+	if (ret)
+		goto err_out;
+	i = avail;
+
+	/* Sanity check: available IB window must be disabled at this point */
+	regval = ioread32(priv->regs + TSI721_IBWIN_LB(i));
+	if (WARN_ON(regval & TSI721_IBWIN_LB_WEN)) {
+		ret = -EIO;
+		goto err_out;
 	}
 
+	ib_win = &priv->ib_win[i];
+	ib_win->active = true;
+	ib_win->rstart = rstart;
+	ib_win->lstart = lstart;
+	ib_win->size = size;
+	spin_unlock(&priv->win_lock);
+
 	iowrite32(TSI721_IBWIN_SIZE(size) << 8,
 			priv->regs + TSI721_IBWIN_SZ(i));
 
@@ -920,6 +946,9 @@
 		i, rstart, (unsigned long long)lstart);
 
 	return 0;
+err_out:
+	spin_unlock(&priv->win_lock);
+	return ret;
 }
 
 /**
@@ -931,25 +960,25 @@
 				dma_addr_t lstart)
 {
 	struct tsi721_device *priv = mport->priv;
+	struct tsi721_ib_win *ib_win;
 	int i;
-	u64 addr;
-	u32 regval;
 
 	/* Search for matching active inbound translation window */
+	spin_lock(&priv->win_lock);
 	for (i = 0; i < TSI721_IBWIN_NUM; i++) {
-		regval = ioread32(priv->regs + TSI721_IBWIN_LB(i));
-		if (regval & TSI721_IBWIN_LB_WEN) {
-			regval = ioread32(priv->regs + TSI721_IBWIN_TUA(i));
-			addr = (u64)regval << 32;
-			regval = ioread32(priv->regs + TSI721_IBWIN_TLA(i));
-			addr |= regval & TSI721_IBWIN_TLA_ADD;
-
-			if (addr == (u64)lstart) {
-				iowrite32(0, priv->regs + TSI721_IBWIN_LB(i));
-				break;
-			}
+		ib_win = &priv->ib_win[i];
+		if (ib_win->active && ib_win->lstart == lstart) {
+			iowrite32(0, priv->regs + TSI721_IBWIN_LB(i));
+			ib_win->active = false;
+			break;
 		}
 	}
+	spin_unlock(&priv->win_lock);
+
+	if (i == TSI721_IBWIN_NUM)
+		dev_err(&priv->pdev->dev,
+			"IB window mapped to %llx not found\n",
+			(unsigned long long)lstart);
 }
 
 /**
@@ -966,6 +995,7 @@
 	/* Disable all SR2PC inbound windows */
 	for (i = 0; i < TSI721_IBWIN_NUM; i++)
 		iowrite32(0, priv->regs + TSI721_IBWIN_LB(i));
+	spin_lock_init(&priv->win_lock);
 }
 
 /**