kernel/x86: init the tsc frequency and clock speed from MSR when available

only for AMD newer CPUs. tested on R5300U

Change-Id: I44be2efca37b1738a759a15140e5fd8d3b5ac7b0
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5804
Reviewed-by: Jérôme Duval <[email protected]>

headers/private/kernel/arch/x86/arch_cpu.h

@@ -120,10 +120,14 @@
 #define IA32_MSR_KERNEL_GS_BASE			0xc0000102
 #define IA32_MSR_TSC_AUX				0xc0000103
 
-// K8 MSR registers
+// AMD MSR registers
+#define MSR_F10H_HWCR						0xc0010015
+#define 	HWCR_TSCFREQSEL					(1 << 24)
 #define K8_MSR_IPM						0xc0010055
+#define MSR_F10H_PSTATEDEF(x)				(0xc0010064 + (x))
+#define 	PSTATEDEF_EN					(1ULL << 63)
 #define MSR_F10H_DE_CFG					0xc0011029
-#define DE_CFG_SERIALIZE_LFENCE			(1 << 1)
+#define 	DE_CFG_SERIALIZE_LFENCE			(1 << 1)
 
 
 // Hardware P-States MSR registers §14.4.1

src/system/kernel/arch/x86/arch_cpu.cpp

@@ -1443,6 +1443,44 @@ init_tsc_with_cpuid(kernel_args* args, uint32* conversionFactor)
 }
 
 
+static void
+init_tsc_with_msr(kernel_args* args, uint32* conversionFactor)
+{
+	cpu_ent* cpuEnt = get_cpu_struct();
+	if (cpuEnt->arch.vendor != VENDOR_AMD)
+		return;
+	uint32 family = cpuEnt->arch.family + cpuEnt->arch.extended_family;
+	if (family < 0x10)
+		return;
+	uint64 value = x86_read_msr(MSR_F10H_HWCR);
+	if ((value & HWCR_TSCFREQSEL) == 0)
+		return;
+
+	value = x86_read_msr(MSR_F10H_PSTATEDEF(0));
+	if ((value & PSTATEDEF_EN) == 0)
+		return;
+	if (family != 0x17 && family != 0x19)
+		return;
+
+	uint64 khz = 200 * 1000;
+	uint32 denominator = (value >> 8) & 0x3f;
+	if (denominator < 0x8 || denominator > 0x2c)
+		return;
+	if (denominator > 0x1a && (denominator % 2) == 1)
+		return;
+	uint32 numerator = value & 0xff;
+	if (numerator < 0x10)
+		return;
+
+	dprintf("CPU: using TSC frequency from MSR %" B_PRIu64 "\n", khz * numerator / denominator);
+	// compute for microseconds as follows (1000000 << 32) / (tsc freq in Hz),
+	// or (1000 << 32) / (tsc freq in kHz)
+	*conversionFactor = (1000ULL << 32) / (khz * numerator / denominator);
+	// overwrite the bootloader value
+	args->arch_args.system_time_cv_factor = *conversionFactor;
+}
+
+
 static void
 init_tsc(kernel_args* args)
 {
@@ -1451,6 +1489,7 @@ init_tsc(kernel_args* args)
 	// try to find the TSC frequency with CPUID
 	uint32 conversionFactor = args->arch_args.system_time_cv_factor;
 	init_tsc_with_cpuid(args, &conversionFactor);
+	init_tsc_with_msr(args, &conversionFactor);
 	uint64 conversionFactorNsecs = (uint64)conversionFactor * 1000;