rapidio/tsi721: add messaging mbox selector parameter

Add module parameter to allow load time configuration of available
RapidIO messaging mailboxes (MBOX1 - MBOX4).

Having a messaging MBOX selector mask allows to define which MBOXes are
controlled by the mport device driver and reserve some of them for
direct use by other drivers.

Link: http://lkml.kernel.org/r/1469125134-16523-7-git-send-email-alexandre.bounine@idt.com
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Tested-by: Barry Wood <barry.wood@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Cc: Barry Wood <barry.wood@idt.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 85098f8..8e07cd5 100644
--- a/drivers/rapidio/devices/tsi721.c
+++ b/drivers/rapidio/devices/tsi721.c
@@ -46,6 +46,11 @@
 module_param(pcie_mrrs, int, S_IRUGO);
 MODULE_PARM_DESC(pcie_mrrs, "PCIe MRRS override value (0...5)");
 
+static u8 mbox_sel = 0x0f;
+module_param(mbox_sel, byte, S_IRUGO);
+MODULE_PARM_DESC(mbox_sel,
+		 "RIO Messaging MBOX Selection Mask (default: 0x0f = all)");
+
 static void tsi721_omsg_handler(struct tsi721_device *priv, int ch);
 static void tsi721_imsg_handler(struct tsi721_device *priv, int ch);
 
@@ -1881,6 +1886,11 @@
 		goto out;
 	}
 
+	if ((mbox_sel & (1 << mbox)) == 0) {
+		rc = -ENODEV;
+		goto out;
+	}
+
 	priv->omsg_ring[mbox].dev_id = dev_id;
 	priv->omsg_ring[mbox].size = entries;
 	priv->omsg_ring[mbox].sts_rdptr = 0;
@@ -2165,6 +2175,11 @@
 		goto out;
 	}
 
+	if ((mbox_sel & (1 << mbox)) == 0) {
+		rc = -ENODEV;
+		goto out;
+	}
+
 	/* Initialize IB Messaging Ring */
 	priv->imsg_ring[mbox].dev_id = dev_id;
 	priv->imsg_ring[mbox].size = entries;