arm64: hyperv: Add Hyper-V clocksource/clockevent support

Add architecture specific definitions and functions needed
by the architecture independent Hyper-V clocksource driver.
Update the Hyper-V clocksource driver to be initialized
on ARM64.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com>

Author: kelleymh

arch/arm64/include/asm/mshyperv.h

@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/arm-smccc.h>
 #include <asm/hyperv-tlfs.h>
+#include <clocksource/arm_arch_timer.h>
 
 /*
  * Declare calls to get and set Hyper-V VP register values on ARM64, which
@@ -41,6 +42,17 @@ static inline u64 hv_get_register(unsigned int reg)
 	return hv_get_vpreg(reg);
 }
 
+/* Define the interrupt ID used by STIMER0 Direct Mode interrupts. This
+ * value can't come from ACPI tables because it is needed before the
+ * Linux ACPI subsystem is initialized.
+ */
+#define HYPERV_STIMER0_VECTOR	31
+
+static inline u64 hv_get_raw_timer(void)
+{
+	return arch_timer_read_counter();
+}
+
 /* SMCCC hypercall parameters */
 #define HV_SMCCC_FUNC_NUMBER	1
 #define HV_FUNC_ID	ARM_SMCCC_CALL_VAL(			\

drivers/clocksource/hyperv_timer.c

@@ -566,3 +566,17 @@ void __init hv_init_clocksource(void)
 	hv_setup_sched_clock(read_hv_sched_clock_msr);
 }
 EXPORT_SYMBOL_GPL(hv_init_clocksource);
+
+/* Initialize everything on ARM64 */
+static int __init hyperv_timer_init(struct acpi_table_header *table)
+{
+	if (!hv_is_hyperv_initialized())
+		return -EINVAL;
+
+	hv_init_clocksource();
+	if (hv_stimer_alloc(true))
+		return -EINVAL;
+
+	return 0;
+}
+TIMER_ACPI_DECLARE(hyperv, ACPI_SIG_GTDT, hyperv_timer_init);