arm64: Add timekeeping

Change-Id: Idc64a00e4dcc787e35afc560acd06a606a6a6964
Reviewed-on: https://review.haiku-os.org/c/haiku/+/10606
Reviewed-by: waddlesplash <[email protected]>

headers/private/system/arch/arm64/arch_real_time_data.h

@@ -8,14 +8,8 @@
 #include <StorageDefs.h>
 #include <SupportDefs.h>
 
-struct arm64_real_time_data {
-	vint64	system_time_offset;
-};
-
 struct arch_real_time_data {
-	struct arm64_real_time_data	data[2];
-	vint32						system_time_conversion_factor;
-	vint32						version;
+	bigtime_t	system_time_offset;
 };
 
 #endif	/* _KERNEL_ARCH_REAL_TIME_DATA_H */

src/system/boot/platform/efi/arch/arm64/arch_start.cpp

@@ -8,6 +8,7 @@
 #include <boot/stage2.h>
 #include <boot/stdio.h>
 
+#include "arm_registers.h"
 #include "efi_platform.h"
 #include "generic_mmu.h"
 #include "mmu.h"
@@ -183,6 +184,7 @@ arch_start_kernel(addr_t kernelEntry)
 	// EL2 without E2H enabled does not, so we need to drop to EL1
 	if (el == 1 || e2h) {
 		arch_mmu_setup_EL1(READ_SPECIALREG(TCR_EL1));
+		WRITE_SPECIALREG(CNTKCTL_EL1, 0b11);
 	} else {
 		arch_mmu_setup_EL1(READ_SPECIALREG(TCR_EL2));
 		arch_cache_disable();

src/system/kernel/arch/arm64/arch_real_time_clock.cpp

@@ -32,11 +32,12 @@ arch_rtc_set_hw_time(uint64 seconds)
 void
 arch_rtc_set_system_time_offset(struct real_time_data *data, bigtime_t offset)
 {
+	atomic_set64(&data->arch_data.system_time_offset, offset);
 }
 
 
 bigtime_t
 arch_rtc_get_system_time_offset(struct real_time_data *data)
 {
-	return 0;
+	return atomic_get64(&data->arch_data.system_time_offset);
 }

src/system/libroot/os/arch/arm64/system_time.c

@@ -12,5 +12,9 @@
 bigtime_t
 system_time(void)
 {
-	return 0;
+	uint64 ticks;
+	uint64 freq;
+	asm volatile("mrs %0, CNTPCT_EL0": "=r" (ticks));
+	asm volatile("mrs %0, CNTFRQ_EL0": "=r" (freq));
+	return (ticks * 1000000) / freq;
 }

src/system/libroot/os/arch/arm64/time.c

@@ -19,5 +19,5 @@ __arch_init_time(struct real_time_data *data, bool setDefaults)
 bigtime_t
 __arch_get_system_time_offset(struct real_time_data *data)
 {
-	return 0;
+	return data->arch_data.system_time_offset;
 }