[U-Boot] [PATCH v2] x86: make the LAPIC / IOAPIC construct switchable with Kconfig

[Hannes Schmelzer]

There are still systems running which do not have any LAPIC or even
IOAPIC. Responsible MSRs for those do not exist and the systems are
crashing on trying setup LAPIC.

So this commit makes the APIC stuff able to switch off for those boards
which dont' have a LAPIC / IOAPIC.

Signed-off-by: Hannes Schmelzer <oe5hpm at oevsv.at>
---

Changes in v2:
- rebase to curent master
- reword commit message to be more clear
- fix typo in Kconfig
- re-add blank line in interrupt.c

 arch/x86/Kconfig              | 9 +++++++++
 arch/x86/cpu/Makefile         | 2 +-
 arch/x86/cpu/i386/interrupt.c | 2 ++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a1c18d2..8d839e4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -736,6 +736,15 @@ config I8259_PIC
 	  slave) interrupt controllers. Include this to have U-Boot set up
 	  the interrupt correctly.
 
+config APIC
+	bool
+	default y
+	help
+	  The (A)dvanced (P)rogrammable (I)nterrupt (C)ontroller is responsible
+	  for catching interrupts and distributing them to one more CPU cores.
+	  In most cases there is some LAPIC (local) for each core and one
+	  I/O APIC. This conjunction is found on most modern x86 systems.
+
 config PINCTRL_ICH6
 	bool
 	help
diff --git a/arch/x86/cpu/Makefile b/arch/x86/cpu/Makefile
index f862d8c..54668aa 100644
--- a/arch/x86/cpu/Makefile
+++ b/arch/x86/cpu/Makefile
@@ -35,7 +35,7 @@ obj-$(CONFIG_NORTHBRIDGE_INTEL_IVYBRIDGE) += ivybridge/
 obj-$(CONFIG_INTEL_QUARK) += quark/
 obj-$(CONFIG_INTEL_QUEENSBAY) += queensbay/
 obj-$(CONFIG_INTEL_TANGIER) += tangier/
-obj-y += lapic.o ioapic.o
+obj-$(CONFIG_APIC) += lapic.o ioapic.o
 obj-y += irq.o
 ifndef CONFIG_$(SPL_)X86_64
 obj-$(CONFIG_SMP) += mp_init.o
diff --git a/arch/x86/cpu/i386/interrupt.c b/arch/x86/cpu/i386/interrupt.c
index ed8423e..bf9526b 100644
--- a/arch/x86/cpu/i386/interrupt.c
+++ b/arch/x86/cpu/i386/interrupt.c
@@ -264,8 +264,10 @@ int interrupt_init(void)
 	i8259_init();
 #endif
 
+#ifdef CONFIG_APIC
 	lapic_setup();
 
+#endif
 	/* Initialize core interrupt and exception functionality of CPU */
 	cpu_init_interrupts();
 
-- 
2.7.4