[kvm-unit-tests PATCH v3 03/27] x86: add few helper functions for apic local timer

[Maxim Levitsky <mlevitsk@redhat.com>]

Add a few functions to apic.c to make it easier to enable and disable
the local apic timer.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 lib/x86/apic.c | 38 ++++++++++++++++++++++++++++++++++++++
 lib/x86/apic.h |  6 ++++++
 2 files changed, 44 insertions(+)

diff --git a/lib/x86/apic.c b/lib/x86/apic.c
index 5131525a..174a8c28 100644
--- a/lib/x86/apic.c
+++ b/lib/x86/apic.c
@@ -256,3 +256,41 @@ void init_apic_map(void)
 			id_map[j++] = i;
 	}
 }
+
+void apic_setup_timer(int vector, u32 mode)
+{
+	apic_cleanup_timer();
+
+	assert((mode & APIC_LVT_TIMER_MASK) == mode);
+
+	apic_write(APIC_TDCR, APIC_TDR_DIV_1);
+	apic_write(APIC_LVTT, vector | mode);
+}
+
+void apic_start_timer(u32 value)
+{
+	/*
+	 * APIC timer runs with 'core crystal clock',
+	 * divided by value in APIC_TDCR
+	 */
+	apic_write(APIC_TMICT, value);
+}
+
+void apic_stop_timer(void)
+{
+	apic_write(APIC_TMICT, 0);
+}
+
+void apic_cleanup_timer(void)
+{
+	u32 lvtt = apic_read(APIC_LVTT);
+
+	// stop the counter
+	apic_stop_timer();
+
+	// mask the timer interrupt
+	apic_write(APIC_LVTT, lvtt | APIC_LVT_MASKED);
+
+	// enable interrupts for one cycle to ensure that a pending timer is serviced
+	sti_nop_cli();
+}
diff --git a/lib/x86/apic.h b/lib/x86/apic.h
index 6d27f047..7c539071 100644
--- a/lib/x86/apic.h
+++ b/lib/x86/apic.h
@@ -58,6 +58,12 @@ void disable_apic(void);
 void reset_apic(void);
 void init_apic_map(void);
 
+void apic_cleanup_timer(void);
+void apic_setup_timer(int vector, u32 mode);
+
+void apic_start_timer(u32 counter);
+void apic_stop_timer(void);
+
 /* Converts byte-addressable APIC register offset to 4-byte offset. */
 static inline u32 apic_reg_index(u32 reg)
 {
-- 
2.34.3