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Subject[tip:x86/apic] x86: Allow platforms to force enable apic
Commit-ID:  5a7ae78fd478624df3059cb6f55056b85d074acc
Gitweb: http://git.kernel.org/tip/5a7ae78fd478624df3059cb6f55056b85d074acc
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Tue, 19 Oct 2010 10:46:28 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 23 Oct 2010 17:27:43 +0200

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>
---
arch/x86/include/asm/apic.h | 1 +
arch/x86/kernel/apic/apic.c | 87 ++++++++++++++++++++++++++----------------
2 files changed, 55 insertions(+), 33 deletions(-)
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 286de34..ad50aaa 100644
--- 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
--- 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();


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