x86: tsc: add support for reading CPU freq from cpuid
Starting with cpuid level 0x16 (Skylake-based processors)
it is possible to get CPU base freq via cpuid.
This fixes booting on a skylake based system.
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: fixed wrong indention of labels]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index c7fefd2..cf86999 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -21,6 +21,17 @@
DECLARE_GLOBAL_DATA_PTR;
+static unsigned long cpu_mhz_from_cpuid(void)
+{
+ if (gd->arch.x86_vendor != X86_VENDOR_INTEL)
+ return 0;
+
+ if (cpuid_eax(0) < 0x16)
+ return 0;
+
+ return cpuid_eax(0x16);
+}
+
/*
* According to Intel 64 and IA-32 System Programming Guide,
* if MSR_PERF_STAT[31] is set, the maximum resolved bus ratio can be
@@ -343,13 +354,21 @@
if (!gd->arch.clock_rate) {
unsigned long fast_calibrate;
- fast_calibrate = cpu_mhz_from_msr();
- if (!fast_calibrate) {
- fast_calibrate = quick_pit_calibrate();
- if (!fast_calibrate)
- panic("TSC frequency is ZERO");
- }
+ fast_calibrate = cpu_mhz_from_cpuid();
+ if (fast_calibrate)
+ goto done;
+ fast_calibrate = cpu_mhz_from_msr();
+ if (fast_calibrate)
+ goto done;
+
+ fast_calibrate = quick_pit_calibrate();
+ if (fast_calibrate)
+ goto done;
+
+ panic("TSC frequency is ZERO");
+
+done:
gd->arch.clock_rate = fast_calibrate * 1000000;
}
}