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 c7fefd20319fcf1c0972c92ee92effdc100ff45d..cf869998bf9cc1da3e3d5f1a28c732996bbc8f63 100644 (file)
--- 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 @@ static void tsc_timer_ensure_setup(void)
        if (!gd->arch.clock_rate) {
                unsigned long fast_calibrate;
 
+               fast_calibrate = cpu_mhz_from_cpuid();
+               if (fast_calibrate)
+                       goto done;
+
                fast_calibrate = cpu_mhz_from_msr();
-               if (!fast_calibrate) {
-                       fast_calibrate = quick_pit_calibrate();
-                       if (!fast_calibrate)
-                               panic("TSC frequency is ZERO");
-               }
+               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;
        }
 }