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https://github.com/brain-hackers/u-boot-brain
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3b621ccabd
On some x86 processors (like Intel Quark) the MTRR registers are not supported. This is reflected by the CPUID (EAX 01H) result EDX[12]. Accessing the MTRR registers on such processors will cause #GP so we must test the support flag before accessing MTRR MSRs. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Acked-by: Simon Glass <sjg@chromium.org>
96 lines
2.2 KiB
C
96 lines
2.2 KiB
C
/*
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* (C) Copyright 2014 Google, Inc
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*
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* SPDX-License-Identifier: GPL-2.0+
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*
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* Memory Type Range Regsters - these are used to tell the CPU whether
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* memory is cacheable and if so the cache write mode to use.
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*
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* These can speed up booting. See the mtrr command.
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*
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* Reference: Intel Architecture Software Developer's Manual, Volume 3:
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* System Programming
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*/
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#include <common.h>
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#include <asm/io.h>
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#include <asm/msr.h>
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#include <asm/mtrr.h>
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DECLARE_GLOBAL_DATA_PTR;
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/* Prepare to adjust MTRRs */
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void mtrr_open(struct mtrr_state *state)
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{
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if (!gd->arch.has_mtrr)
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return;
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state->enable_cache = dcache_status();
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if (state->enable_cache)
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disable_caches();
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state->deftype = native_read_msr(MTRR_DEF_TYPE_MSR);
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wrmsrl(MTRR_DEF_TYPE_MSR, state->deftype & ~MTRR_DEF_TYPE_EN);
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}
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/* Clean up after adjusting MTRRs, and enable them */
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void mtrr_close(struct mtrr_state *state)
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{
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if (!gd->arch.has_mtrr)
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return;
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wrmsrl(MTRR_DEF_TYPE_MSR, state->deftype | MTRR_DEF_TYPE_EN);
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if (state->enable_cache)
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enable_caches();
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}
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int mtrr_commit(bool do_caches)
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{
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struct mtrr_request *req = gd->arch.mtrr_req;
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struct mtrr_state state;
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uint64_t mask;
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int i;
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if (!gd->arch.has_mtrr)
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return -ENOSYS;
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mtrr_open(&state);
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for (i = 0; i < gd->arch.mtrr_req_count; i++, req++) {
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mask = ~(req->size - 1);
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mask &= (1ULL << CONFIG_CPU_ADDR_BITS) - 1;
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wrmsrl(MTRR_PHYS_BASE_MSR(i), req->start | req->type);
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wrmsrl(MTRR_PHYS_MASK_MSR(i), mask | MTRR_PHYS_MASK_VALID);
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}
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/* Clear the ones that are unused */
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for (; i < MTRR_COUNT; i++)
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wrmsrl(MTRR_PHYS_MASK_MSR(i), 0);
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mtrr_close(&state);
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return 0;
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}
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int mtrr_add_request(int type, uint64_t start, uint64_t size)
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{
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struct mtrr_request *req;
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uint64_t mask;
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if (!gd->arch.has_mtrr)
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return -ENOSYS;
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if (gd->arch.mtrr_req_count == MAX_MTRR_REQUESTS)
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return -ENOSPC;
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req = &gd->arch.mtrr_req[gd->arch.mtrr_req_count++];
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req->type = type;
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req->start = start;
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req->size = size;
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debug("%d: type=%d, %08llx %08llx\n", gd->arch.mtrr_req_count - 1,
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req->type, req->start, req->size);
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mask = ~(req->size - 1);
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mask &= (1ULL << CONFIG_CPU_ADDR_BITS) - 1;
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mask |= MTRR_PHYS_MASK_VALID;
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debug(" %016llx %016llx\n", req->start | req->type, mask);
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return 0;
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}
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