tsc: Use alternative delay sources whenever appropriate.

PIT isn't available on some of new hardware including Hyper-V. So
use pmtimer for calibration. Moreover pmtimer calibration is faster, so
use it on coreboor where booting time is important.

Based on patch by Michael Chang.

grub-core/kern/i386/tsc_pmtimer.c

@@ -0,0 +1,160 @@
+/* kern/i386/tsc.c - x86 TSC time source implementation
+ * Requires Pentium or better x86 CPU that supports the RDTSC instruction.
+ * This module uses the PIT to calibrate the TSC to
+ * real time.
+ *
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2008  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/types.h>
+#include <grub/time.h>
+#include <grub/misc.h>
+#include <grub/i386/tsc.h>
+#include <grub/acpi.h>
+#include <grub/cpu/io.h>
+
+static void *
+grub_acpi_rsdt_find_table (struct grub_acpi_table_header *rsdt, const char *sig)
+{
+  grub_size_t s;
+  grub_uint32_t *ptr;
+
+  if (!rsdt)
+    return 0;
+
+  if (grub_memcmp (rsdt->signature, "RSDT", 4) != 0)
+    return 0;
+
+  ptr = (grub_uint32_t *) (rsdt + 1);
+  s = (rsdt->length - sizeof (*rsdt)) / sizeof (grub_uint32_t);
+  for (; s; s--, ptr++)
+    {
+      struct grub_acpi_table_header *tbl;
+      tbl = (struct grub_acpi_table_header *) (grub_addr_t) *ptr;
+      if (grub_memcmp (tbl->signature, sig, 4) == 0)
+	return tbl;
+    }
+  return 0;
+}
+
+static void *
+grub_acpi_xsdt_find_table (struct grub_acpi_table_header *xsdt, const char *sig)
+{
+  grub_size_t s;
+  grub_uint64_t *ptr;
+
+  if (!xsdt)
+    return 0;
+
+  if (grub_memcmp (xsdt->signature, "XSDT", 4) != 0)
+    return 0;
+
+  ptr = (grub_uint64_t *) (xsdt + 1);
+  s = (xsdt->length - sizeof (*xsdt)) / sizeof (grub_uint32_t);
+  for (; s; s--, ptr++)
+    {
+      struct grub_acpi_table_header *tbl;
+#if GRUB_CPU_SIZEOF_VOID_P != 8
+      if (*ptr >> 32)
+	continue;
+#endif
+      tbl = (struct grub_acpi_table_header *) (grub_addr_t) *ptr;
+      if (grub_memcmp (tbl->signature, sig, 4) == 0)
+	return tbl;
+    }
+  return 0;
+}
+
+struct grub_acpi_fadt *
+grub_acpi_find_fadt (void)
+{
+  struct grub_acpi_fadt *fadt = 0;
+  struct grub_acpi_rsdp_v10 *rsdpv1;
+  struct grub_acpi_rsdp_v20 *rsdpv2;
+  rsdpv1 = grub_machine_acpi_get_rsdpv1 ();
+  if (rsdpv1)
+    fadt = grub_acpi_rsdt_find_table ((struct grub_acpi_table_header *)
+				      (grub_addr_t) rsdpv1->rsdt_addr,
+				      GRUB_ACPI_FADT_SIGNATURE);
+  if (fadt)
+    return fadt;
+  rsdpv2 = grub_machine_acpi_get_rsdpv2 ();
+  if (rsdpv2)
+    fadt = grub_acpi_rsdt_find_table ((struct grub_acpi_table_header *)
+				      (grub_addr_t) rsdpv2->rsdpv1.rsdt_addr,
+				      GRUB_ACPI_FADT_SIGNATURE);
+  if (fadt)
+    return fadt;
+  if (rsdpv2
+#if GRUB_CPU_SIZEOF_VOID_P != 8
+      && !(rsdpv2->xsdt_addr >> 32)
+#endif
+      )
+    fadt = grub_acpi_xsdt_find_table ((struct grub_acpi_table_header *)
+				      (grub_addr_t) rsdpv2->xsdt_addr,
+				      GRUB_ACPI_FADT_SIGNATURE);
+  if (fadt)
+    return fadt;
+  return 0;
+}
+
+int
+grub_tsc_calibrate_from_pmtimer (void)
+{
+  grub_uint32_t start;
+  grub_uint32_t last;
+  grub_uint32_t cur, end;
+  struct grub_acpi_fadt *fadt;
+  grub_port_t p;
+  grub_uint64_t start_tsc;
+  grub_uint64_t end_tsc;
+  int num_iter = 0;
+
+  fadt = grub_acpi_find_fadt ();
+  if (!fadt)
+    return 0;
+  p = fadt->pmtimer;
+  if (!p)
+    return 0;
+
+  start = grub_inl (p) & 0xffffff;
+  last = start;
+  /* It's 3.579545 MHz clock. Wait 1 ms.  */
+  end = start + 3580;
+  start_tsc = grub_get_tsc ();
+  while (1)
+    {
+      cur = grub_inl (p) & 0xffffff;
+      if (cur < last)
+	cur |= 0x1000000;
+      num_iter++;
+      if (cur >= end)
+	{
+	  end_tsc = grub_get_tsc ();
+	  grub_tsc_rate = grub_divmod64 ((1ULL << 32), end_tsc - start_tsc, 0);
+	  return 1;
+	}
+      /* Check for broken PM timer.
+	 50000000 TSCs is between 5 ms (10GHz) and 200 ms (250 MHz)
+	 if after this time we still don't have 1 ms on pmtimer, then
+	 pmtimer is broken.
+       */
+      if ((num_iter & 0xffffff) == 0 && grub_get_tsc () - start_tsc > 5000000) {
+	return 0;
+      }
+    }
+}