70 lines
1.9 KiB
C
70 lines
1.9 KiB
C
/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2008,2009 Free Software Foundation, Inc.
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*
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* GRUB is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef KERNEL_CPU_TSC_HEADER
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#define KERNEL_CPU_TSC_HEADER 1
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#include <grub/types.h>
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#include <grub/i386/cpuid.h>
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void grub_tsc_init (void);
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/* In ms per 2^32 ticks. */
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extern grub_uint32_t EXPORT_VAR(grub_tsc_rate);
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int
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grub_tsc_calibrate_from_xen (void);
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int
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grub_tsc_calibrate_from_efi (void);
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int
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grub_tsc_calibrate_from_pmtimer (void);
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int
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grub_tsc_calibrate_from_pit (void);
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/* Read the TSC value, which increments with each CPU clock cycle. */
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static __inline grub_uint64_t
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grub_get_tsc (void)
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{
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grub_uint32_t lo, hi;
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grub_uint32_t a,b,c,d;
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/* The CPUID instruction is a 'serializing' instruction, and
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avoids out-of-order execution of the RDTSC instruction. */
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grub_cpuid (0,a,b,c,d);
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/* Read TSC value. We cannot use "=A", since this would use
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%rax on x86_64. */
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__asm__ __volatile__ ("rdtsc":"=a" (lo), "=d" (hi));
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return (((grub_uint64_t) hi) << 32) | lo;
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}
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static __inline int
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grub_cpu_is_tsc_supported (void)
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{
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#ifndef GRUB_MACHINE_XEN
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grub_uint32_t a,b,c,d;
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if (! grub_cpu_is_cpuid_supported ())
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return 0;
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grub_cpuid(1,a,b,c,d);
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return (d & (1 << 4)) != 0;
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#else
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return 1;
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#endif
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}
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#endif /* ! KERNEL_CPU_TSC_HEADER */
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