[PATCH] PCI Allow OutOfRange PIRQ table address

I updated this to remove unnecessary variable initialization, make
check_routing be inline only and not __init, switch to strtoul, and
formatting fixes as per Randy Dunlap's recommendations.

I updated this to change pirq_table_addr to a long, and to add a warning
msg if the PIRQ table wasn't found at the specified address, as per thread
with Matthew Wilcox.

In our hardware situation, the BIOS is unable to store or generate it's PIRQ
table in the F0000h-100000h standard range. This patch adds a pci kernel
parameter, pirqaddr to allow the bootloader (or BIOS based loader) to inform
the kernel where the PIRQ table got stored. A beneficial side-effect is that,
if one's BIOS uses a static address each time for it's PIRQ table, then
pirqaddr can be used to avoid the $pirq search through that address block each
time at boot for normal PIRQ BIOSes.

Signed-off-by: Jaya Kumar <jayalk@intworks.biz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 37 insertions, 14 deletions

diff --git a/arch/i386/pci/irq.c b/arch/i386/pci/irq.c
index 83458f81e66..78ca1ecbb90 100644
--- a/arch/i386/pci/irq.c
+++ b/arch/i386/pci/irq.c
@@ -58,6 +58,35 @@ struct irq_router_handler {
 int (*pcibios_enable_irq)(struct pci_dev *dev) = NULL;
 
 /*
+ *  Check passed address for the PCI IRQ Routing Table signature
+ *  and perform checksum verification.
+ */
+
+static inline struct irq_routing_table * pirq_check_routing_table(u8 *addr)
+{
+	struct irq_routing_table *rt;
+	int i;
+	u8 sum;
+
+	rt = (struct irq_routing_table *) addr;
+	if (rt->signature != PIRQ_SIGNATURE ||
+	    rt->version != PIRQ_VERSION ||
+	    rt->size % 16 ||
+	    rt->size < sizeof(struct irq_routing_table))
+		return NULL;
+	sum = 0;
+	for (i=0; i < rt->size; i++)
+		sum += addr[i];
+	if (!sum) {
+		DBG("PCI: Interrupt Routing Table found at 0x%p\n", rt);
+		return rt;
+	}
+	return NULL;
+}
+
+
+
+/*
  *  Search 0xf0000 -- 0xfffff for the PCI IRQ Routing Table.
  */
 
@@ -65,23 +94,17 @@ static struct irq_routing_table * __init pirq_find_routing_table(void)
 {
 	u8 *addr;
 	struct irq_routing_table *rt;
-	int i;
-	u8 sum;
 
+	if (pirq_table_addr) {
+		rt = pirq_check_routing_table((u8 *) __va(pirq_table_addr));
+		if (rt)
+			return rt;
+		printk(KERN_WARNING "PCI: PIRQ table NOT found at pirqaddr\n");
+	}
 	for(addr = (u8 *) __va(0xf0000); addr < (u8 *) __va(0x100000); addr += 16) {
-		rt = (struct irq_routing_table *) addr;
-		if (rt->signature != PIRQ_SIGNATURE ||
-		    rt->version != PIRQ_VERSION ||
-		    rt->size % 16 ||
-		    rt->size < sizeof(struct irq_routing_table))
-			continue;
-		sum = 0;
-		for(i=0; i<rt->size; i++)
-			sum += addr[i];
-		if (!sum) {
-			DBG("PCI: Interrupt Routing Table found at 0x%p\n", rt);
+		rt = pirq_check_routing_table(addr);
+		if (rt)
 			return rt;
-		}
 	}
 	return NULL;
 }