x86: Allow platforms to force enable apic

Some embedded x86 platforms don't setup the APIC in the
BIOS/bootloader and would be forced to add "lapic" on the kernel
command line. That's a bit akward.

Split out the force enable code from detect_init_APIC() and allow
platform code to call it from the platform setup. That avoids the
command line parameter and possible replication of the MSR dance in
the force enable code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1287510389-8388-1-git-send-email-dirk.brandewie@gmail.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 286de34..ad50aaa 100644 (file)
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -238,6 +238,7 @@ extern void setup_boot_APIC_clock(void);
 extern void setup_secondary_APIC_clock(void);
 extern int APIC_init_uniprocessor(void);
 extern void enable_NMI_through_LVT0(void);
+extern int apic_force_enable(void);
 
 /*
  * On 32bit this is mach-xxx local

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 850657d..4638396 100644 (file)
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1531,13 +1531,60 @@ static int __init detect_init_APIC(void)
        return 0;
 }
 #else
+
+static int apic_verify(void)
+{
+       u32 features, h, l;
+
+       /*
+        * The APIC feature bit should now be enabled
+        * in `cpuid'
+        */
+       features = cpuid_edx(1);
+       if (!(features & (1 << X86_FEATURE_APIC))) {
+               pr_warning("Could not enable APIC!\n");
+               return -1;
+       }
+       set_cpu_cap(&boot_cpu_data, X86_FEATURE_APIC);
+       mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
+
+       /* The BIOS may have set up the APIC at some other address */
+       rdmsr(MSR_IA32_APICBASE, l, h);
+       if (l & MSR_IA32_APICBASE_ENABLE)
+               mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;
+
+       pr_info("Found and enabled local APIC!\n");
+       return 0;
+}
+
+int apic_force_enable(void)
+{
+       u32 h, l;
+
+       if (disable_apic)
+               return -1;
+
+       /*
+        * Some BIOSes disable the local APIC in the APIC_BASE
+        * MSR. This can only be done in software for Intel P6 or later
+        * and AMD K7 (Model > 1) or later.
+        */
+       rdmsr(MSR_IA32_APICBASE, l, h);
+       if (!(l & MSR_IA32_APICBASE_ENABLE)) {
+               pr_info("Local APIC disabled by BIOS -- reenabling.\n");
+               l &= ~MSR_IA32_APICBASE_BASE;
+               l |= MSR_IA32_APICBASE_ENABLE | APIC_DEFAULT_PHYS_BASE;
+               wrmsr(MSR_IA32_APICBASE, l, h);
+               enabled_via_apicbase = 1;
+       }
+       return apic_verify();
+}
+
 /*
  * Detect and initialize APIC
  */
 static int __init detect_init_APIC(void)
 {
-       u32 h, l, features;
-
        /* Disabled by kernel option? */
        if (disable_apic)
                return -1;
@@ -1567,38 +1614,12 @@ static int __init detect_init_APIC(void)
                                "you can enable it with \"lapic\"\n");
                        return -1;
                }
-               /*
-                * Some BIOSes disable the local APIC in the APIC_BASE
-                * MSR. This can only be done in software for Intel P6 or later
-                * and AMD K7 (Model > 1) or later.
-                */
-               rdmsr(MSR_IA32_APICBASE, l, h);
-               if (!(l & MSR_IA32_APICBASE_ENABLE)) {
-                       pr_info("Local APIC disabled by BIOS -- reenabling.\n");
-                       l &= ~MSR_IA32_APICBASE_BASE;
-                       l |= MSR_IA32_APICBASE_ENABLE | APIC_DEFAULT_PHYS_BASE;
-                       wrmsr(MSR_IA32_APICBASE, l, h);
-                       enabled_via_apicbase = 1;
-               }
-       }
-       /*
-        * The APIC feature bit should now be enabled
-        * in `cpuid'
-        */
-       features = cpuid_edx(1);
-       if (!(features & (1 << X86_FEATURE_APIC))) {
-               pr_warning("Could not enable APIC!\n");
-               return -1;
+               if (apic_force_enable())
+                       return -1;
+       } else {
+               if (apic_verify())
+                       return -1;
        }
-       set_cpu_cap(&boot_cpu_data, X86_FEATURE_APIC);
-       mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
-
-       /* The BIOS may have set up the APIC at some other address */
-       rdmsr(MSR_IA32_APICBASE, l, h);
-       if (l & MSR_IA32_APICBASE_ENABLE)
-               mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;
-
-       pr_info("Found and enabled local APIC!\n");
 
        apic_pm_activate();