[rfc 2/4] x86: apic - introduce imcr_ helpers

Cyrill Gorcunov
2009-04-12T16:51:34Z

[-- Attachment #1: x86-apic-imcr --]
[-- Type: text/plain, Size: 1801 bytes --]

Impact: cleanup

Distinguish port writting magic into helpers with comments.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
---
arch/x86/kernel/apic/apic.c | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)

Index: linux-2.6.git/arch/x86/kernel/apic/apic.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/apic/apic.c
+++ linux-2.6.git/arch/x86/kernel/apic/apic.c
@@ -99,6 +99,29 @@ 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
@@ -1737,8 +1760,7 @@ 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)
@@ -1766,8 +1788,7 @@ void disconnect_bsp_APIC(int virt_wire_s
*/
apic_printk(APIC_VERBOSE, "disabling APIC mode, "
"entering PIC mode.\n");
- outb(0x70, 0x22);
- outb(0x00, 0x23);
+ imcr_apic_to_pic();
return;
}
#endif