Improve the mapping between the hardware PCI bus numbering on multi-hose

tsunami systems and the PCI bus-numbering system of FreeBSD.  Eg, the former
allows for 2 PCI bus 2's (one each on hoses 0 and 1) while the latter
needs to give each PCI bus a unique monotonically increasing number.

It has been fairly well tested and correctly maps machines with a ppb on
hose 1 as well as machines with ppbs on both hoses.

DS10s remain untested, as I do not have a pci card with a ppb which will
pass POST in a tsunami.

This is a house of cards.

1 files changed, 73 insertions, 9 deletions

diff --git a/sys/alpha/pci/tsunami_pci.c b/sys/alpha/pci/tsunami_pci.c
index 87ea867..c5301d1 100644
--- a/sys/alpha/pci/tsunami_pci.c
+++ b/sys/alpha/pci/tsunami_pci.c
@@ -41,40 +41,104 @@
 
 static devclass_t	pcib_devclass;
 
-int tsunami_hoses[TSUNAMI_MAXHOSES+1] = {0,-1,-1,-1,-1};
+int tsunami_hoses[TSUNAMI_MAXHOSES+1] = {1,-1,-1,-1,-1};
+
+int tsunami_maxhoseno = 0;
+
+extern int tsunami_num_pchips;
+
+/* 
+ * This comment attempts to explain why and how we are mapping from
+ * the DEQ assigned bus numbers to the FreeBSD assigned numbers.
+ *
+ * FreeBSD must number buses with monotonically increasing numbers for a 
+ * variety of reasons (pciconf, newbus, etc).  
+ *
+ * DEQ numbers them (from what I can tell) on a per-hose bases. And
+ * for some reason they seem to always leave bus 1 unused.
+ * 
+ * When generating config space addrs, we need to know if we are
+ * directly on the primary bus on that hose, or if we are behind a ppb.
+ * We keep track of this by assigning hoses monotonically increasing
+ * numbers.  This fits nicely with DEQ not using bus number 1; I
+ * assume that is what it as intended for. I guess we'll see if they 
+ * come out with a system using more than one pchip..
+ *
+ * Next, we must attempt to map the FreeBSD assigned numbers to the
+ * numbers assigned by DEQ in order to generate proper config space 
+ * addrs.  We store the next number past the 0th bus of our hose and
+ * do subtraction to determine what the DEQ number should have been,
+ * given a FreeBSD bus number.  This is disgusting & quite possibly
+ * wrong.  
+ */
 
 int
 tsunami_bus_within_hose(int hose, int bus)
 {
-	return(bus - tsunami_hoses[hose]);
+	if (hose == bus)
+		return 0;
+	else 
+		return ( (bus - tsunami_hoses[hose]) 
+		    + (tsunami_num_pchips - 1)); /* XXX */
+	/* 
+	 * XXX (tsunami_num_pchips - 1) is a just a guess!
+	 *
+	 * I assume that a ppb in a ds10 will get bus 1
+	 * if it is assigned bus 2, then replace 
+	 * (tsunami_num_pchips - 1) with 1.
+	 */
 }
 
+/* 
+ * this function supports pciconf ioctls 
+ */
+
 int 
 tsunami_hose_from_bus(int bus)
 {
 	int i;
-	for(i = 1; i <= TSUNAMI_MAXHOSES && tsunami_hoses[i] != -1; i++){
-		if(tsunami_hoses[i] > bus)
+
+	if (bus < tsunami_maxhoseno)
+		return bus;
+
+	for (i = 1; i <= TSUNAMI_MAXHOSES && tsunami_hoses[i] != -1; i++){
+		if(tsunami_hoses[i] >= bus)
 			return i-1;
 	}
+
 	return i-1;
-	
 }
 
 
 static int
 tsunami_pcib_probe(device_t dev)
 {
-	static int hoseno = 0;
+	static int error;
 	device_t child;
+	int lastbus;
 
 	device_set_desc(dev, "21271 PCI host bus adapter");
 
 	child = device_add_child(dev, "pci", -1);
 
-	if(hoseno)
-		tsunami_hoses[hoseno] = device_get_unit(child);
-	hoseno++;
+	if (tsunami_maxhoseno) {
+		    lastbus = (device_get_unit(child) - 1);
+		    if (lastbus == 0) /* didn't have a ppb on hose 0 */
+			    lastbus++;
+		    tsunami_hoses[tsunami_maxhoseno] = lastbus;
+	}
+	if ((error = device_delete_child(dev, child)))
+		panic("tsunami_pcib_probe: device_delete_child failed\n");
+	
+	child = device_add_child(dev, "pci", tsunami_maxhoseno);
+
+	if (tsunami_maxhoseno != device_get_unit(child)) {
+		printf("tsunami_pcib_probe: wanted unit %d ", 
+		    tsunami_maxhoseno);
+		printf(" got unit %d\n", device_get_unit(child));
+		panic("tsunami_pcib_probe: incorrect bus numbering");
+	}
+	tsunami_maxhoseno++;
 	return 0;
 }