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>
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 098ec84..c3be10f5 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -98,6 +98,29 @@
/* 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 @@
*/
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 @@
*/
apic_printk(APIC_VERBOSE, "disabling APIC mode, "
"entering PIC mode.\n");
- outb(0x70, 0x22);
- outb(0x00, 0x23);
+ imcr_apic_to_pic();
return;
}
#endif