sb,soc/intel: Set IOAPIC redirection entry count

The number of redirection table entries (aka interrupt vectors) inside
an I/O APIC may depend of the SKU, with the related register being of
type read/write-once. Provide support utilities to either lock or set
this registers value.

Change-Id: I8da869ba390dd821b43032e4ccbc9291c39e6bab
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55289
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/southbridge/intel/i82801ix/lpc.c b/src/southbridge/intel/i82801ix/lpc.c
index 866ede9..21f1faa 100644
--- a/src/southbridge/intel/i82801ix/lpc.c
+++ b/src/southbridge/intel/i82801ix/lpc.c
@@ -27,20 +27,13 @@
 
 static void i82801ix_enable_apic(struct device *dev)
 {
-	u32 reg32;
-	volatile u32 *ioapic_index = (volatile u32 *)(IO_APIC_ADDR);
-	volatile u32 *ioapic_data = (volatile u32 *)(IO_APIC_ADDR + 0x10);
-
 	/* Enable IOAPIC. Keep APIC Range Select at zero. */
 	RCBA8(0x31ff) = 0x03;
 	/* We have to read 0x31ff back if bit0 changed. */
 	RCBA8(0x31ff);
 
 	/* Lock maximum redirection entries (MRE), R/WO register. */
-	*ioapic_index	= 0x01;
-	reg32		= *ioapic_data;
-	*ioapic_index	= 0x01;
-	*ioapic_data	= reg32;
+	ioapic_lock_max_vectors(VIO_APIC_VADDR);
 
 	setup_ioapic(VIO_APIC_VADDR, 2); /* ICH7 code uses id 2. */
 }