[coreboot] New patch to review for coreboot: 91f016f Fix reading of number of interrupts for IO-APICs

[Patrick Georgi (patrick@georgi-clan.de)]

Patrick Georgi (patrick at georgi-clan.de) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/1624

-gerrit

commit 91f016fb77ca94e50ecb6723035bf29b1547aaf8
Author: Nico Huber <nico.huber at secunet.com>
Date:   Mon Sep 24 10:48:43 2012 +0200

    Fix reading of number of interrupts for IO-APICs
    
    The number read from the io-apic register represents the index of the
    highest interrupt redirection entry, i.e. the number of interrupts
    minus one.
    
    Change-Id: I54c992e4ff400de24bb9fef5d82251078f92c588
    Signed-off-by: Nico Huber <nico.huber at secunet.com>
---
 src/arch/x86/lib/ioapic.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/arch/x86/lib/ioapic.c b/src/arch/x86/lib/ioapic.c
index 57b99e2..018a42c 100644
--- a/src/arch/x86/lib/ioapic.c
+++ b/src/arch/x86/lib/ioapic.c
@@ -85,8 +85,11 @@ void setup_ioapic(u32 ioapic_base, u8 ioapic_id)
 
 	/* Read the available number of interrupts. */
 	ioapic_interrupts = (io_apic_read(ioapic_base, 0x01) >> 16) & 0xff;
-	if (!ioapic_interrupts || ioapic_interrupts == 0xff)
-		ioapic_interrupts = 24;
+	if (ioapic_interrupts == 0xff)
+		ioapic_interrupts = 23;
+	ioapic_interrupts += 1; /* Bits 23-16 specify the maximum redirection
+				   entry, which is the number of interrupts
+				   minus 1. */
 	printk(BIOS_DEBUG, "IOAPIC: %d interrupts\n", ioapic_interrupts);
 
 #if CONFIG_IOAPIC_INTERRUPTS_ON_FSB