x86: apic - introduce imcr_ helpers

Impact: cleanup

Distinguish port writting magic into helpers with comments.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <20090412165058.535921550@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 25 insertions, 4 deletions

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 098ec84b8c00..c3be10f5773e 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -98,6 +98,29 @@ early_param("lapic", parse_lapic);
 /* Local APIC was disabled by the BIOS and enabled by the kernel */
 static int enabled_via_apicbase;
 
+/*
+ * Handle interrupt mode configuration register (IMCR).
+ * This register controls whether the interrupt signals
+ * that reach the BSP come from the master PIC or from the
+ * local APIC. Before entering Symmetric I/O Mode, either
+ * the BIOS or the operating system must switch out of
+ * PIC Mode by changing the IMCR.
+ */
+static inline imcr_pic_to_apic(void)
+{
+        /* select IMCR register */
+        outb(0x70, 0x22);
+        /* NMI and 8259 INTR go through APIC */
+        outb(0x01, 0x23);
+}
+
+static inline imcr_apic_to_pic(void)
+{
+        /* select IMCR register */
+        outb(0x70, 0x22);
+        /* NMI and 8259 INTR go directly to BSP */
+        outb(0x00, 0x23);
+}
 #endif
 
 #ifdef CONFIG_X86_64
@@ -1727,8 +1750,7 @@ void __init connect_bsp_APIC(void)
                  */
                 apic_printk(APIC_VERBOSE, "leaving PIC mode, "
                                 "enabling APIC mode.\n");
-                outb(0x70, 0x22);
-                outb(0x01, 0x23);
+                imcr_pic_to_apic();
         }
 #endif
         if (apic->enable_apic_mode)
@@ -1756,8 +1778,7 @@ void disconnect_bsp_APIC(int virt_wire_setup)
                  */
                 apic_printk(APIC_VERBOSE, "disabling APIC mode, "
                                 "entering PIC mode.\n");
-                outb(0x70, 0x22);
-                outb(0x00, 0x23);
+                imcr_apic_to_pic();
                 return;
         }
 #endif