x86/tsc: Allow TSC calibration without PIT

[mirror_ubuntu-bionic-kernel.git] / arch / x86 / kernel / tsc.c

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 0c2bb26e5aaaadcb517c3ec76ce83fe3c68c35af..c2a16c83118e1dc41919ca95232927f35492ee00 100644 (file)
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -25,6 +25,7 @@
 #include <asm/geode.h>
 #include <asm/apic.h>
 #include <asm/intel-family.h>
+#include <asm/i8259.h>
 
 unsigned int __read_mostly cpu_khz;    /* TSC clocks / usec, not used here */
 EXPORT_SYMBOL(cpu_khz);
@@ -363,6 +364,20 @@ static unsigned long pit_calibrate_tsc(u32 latch, unsigned long ms, int loopmin)
        unsigned long tscmin, tscmax;
        int pitcnt;
 
+       if (!has_legacy_pic()) {
+               /*
+                * Relies on tsc_early_delay_calibrate() to have given us semi
+                * usable udelay(), wait for the same 50ms we would have with
+                * the PIT loop below.
+                */
+               udelay(10 * USEC_PER_MSEC);
+               udelay(10 * USEC_PER_MSEC);
+               udelay(10 * USEC_PER_MSEC);
+               udelay(10 * USEC_PER_MSEC);
+               udelay(10 * USEC_PER_MSEC);
+               return ULONG_MAX;
+       }
+
        /* Set the Gate high, disable speaker */
        outb((inb(0x61) & ~0x02) | 0x01, 0x61);
 
@@ -487,6 +502,9 @@ static unsigned long quick_pit_calibrate(void)
        u64 tsc, delta;
        unsigned long d1, d2;
 
+       if (!has_legacy_pic())
+               return 0;
+
        /* Set the Gate high, disable speaker */
        outb((inb(0x61) & ~0x02) | 0x01, 0x61);