c5ae124e11
The cycle register is not guaranteed to count at constant frequency. If it is counting at all depends on the state the performance monitoring unit. Use the time register to measure time. Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
79 lines
2.0 KiB
C
79 lines
2.0 KiB
C
/* init.c - initialize a riscv-based EFI system */
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/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2018 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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#include <grub/env.h>
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#include <grub/kernel.h>
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#include <grub/misc.h>
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#include <grub/mm.h>
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#include <grub/time.h>
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#include <grub/efi/efi.h>
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#include <grub/loader.h>
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static grub_uint64_t timer_frequency_in_khz;
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static grub_uint64_t
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grub_efi_get_time_ms (void)
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{
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grub_uint64_t tmr;
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#if __riscv_xlen == 64
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asm volatile ("rdtime %0" : "=r"(tmr));
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#else
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grub_uint32_t lo, hi, tmp;
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asm volatile ("1:\n"
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"rdtimeh %0\n"
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"rdtime %1\n"
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"rdtimeh %2\n"
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"bne %0, %2, 1b"
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: "=&r" (hi), "=&r" (lo), "=&r" (tmp));
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tmr = ((grub_uint64_t)hi << 32) | lo;
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#endif
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return tmr / timer_frequency_in_khz;
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}
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void
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grub_machine_init (void)
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{
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grub_uint64_t time_before, time_after;
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grub_efi_init ();
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/* Calculate timer frequency */
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timer_frequency_in_khz = 1;
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time_before = grub_efi_get_time_ms();
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grub_efi_stall(1000);
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time_after = grub_efi_get_time_ms();
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timer_frequency_in_khz = time_after - time_before;
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grub_install_get_time_ms (grub_efi_get_time_ms);
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}
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void
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grub_machine_fini (int flags)
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{
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if (!(flags & GRUB_LOADER_FLAG_NORETURN))
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return;
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grub_efi_fini ();
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if (!(flags & GRUB_LOADER_FLAG_EFI_KEEP_ALLOCATED_MEMORY))
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grub_efi_memory_fini ();
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}
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