From aff2523f6998dca1f667aa0d26cc8f351c5628dc Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Thu, 1 Jan 2015 16:18:07 -0700 Subject: x86: Add support for MTRRs Memory Type Range Registers are used to tell the CPU whether memory is cacheable and if so the cache write mode to use. Clean up the existing header file to follow style, and remove the unneeded code. These can speed up booting so should be supported. Add these to global_data so they can be requested while booting. We will apply the changes during relocation (in a later commit). Signed-off-by: Simon Glass --- arch/x86/cpu/mtrr.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 arch/x86/cpu/mtrr.c (limited to 'arch/x86/cpu/mtrr.c') diff --git a/arch/x86/cpu/mtrr.c b/arch/x86/cpu/mtrr.c new file mode 100644 index 0000000000..d5a825d181 --- /dev/null +++ b/arch/x86/cpu/mtrr.c @@ -0,0 +1,81 @@ +/* + * (C) Copyright 2014 Google, Inc + * + * SPDX-License-Identifier: GPL-2.0+ + * + * Memory Type Range Regsters - these are used to tell the CPU whether + * memory is cacheable and if so the cache write mode to use. + * + * These can speed up booting. See the mtrr command. + * + * Reference: Intel Architecture Software Developer's Manual, Volume 3: + * System Programming + */ + +#include +#include +#include +#include + +/* Prepare to adjust MTRRs */ +void mtrr_open(struct mtrr_state *state) +{ + state->enable_cache = dcache_status(); + + if (state->enable_cache) + disable_caches(); + state->deftype = native_read_msr(MTRR_DEF_TYPE_MSR); + wrmsrl(MTRR_DEF_TYPE_MSR, state->deftype & ~MTRR_DEF_TYPE_EN); +} + +/* Clean up after adjusting MTRRs, and enable them */ +void mtrr_close(struct mtrr_state *state) +{ + wrmsrl(MTRR_DEF_TYPE_MSR, state->deftype | MTRR_DEF_TYPE_EN); + if (state->enable_cache) + enable_caches(); +} + +int mtrr_commit(bool do_caches) +{ + struct mtrr_request *req = gd->arch.mtrr_req; + struct mtrr_state state; + uint64_t mask; + int i; + + mtrr_open(&state); + for (i = 0; i < gd->arch.mtrr_req_count; i++, req++) { + mask = ~(req->size - 1); + mask &= (1ULL << CONFIG_CPU_ADDR_BITS) - 1; + wrmsrl(MTRR_PHYS_BASE_MSR(i), req->start | req->type); + wrmsrl(MTRR_PHYS_MASK_MSR(i), mask | MTRR_PHYS_MASK_VALID); + } + + /* Clear the ones that are unused */ + for (; i < MTRR_COUNT; i++) + wrmsrl(MTRR_PHYS_MASK_MSR(i), 0); + mtrr_close(&state); + + return 0; +} + +int mtrr_add_request(int type, uint64_t start, uint64_t size) +{ + struct mtrr_request *req; + uint64_t mask; + + if (gd->arch.mtrr_req_count == MAX_MTRR_REQUESTS) + return -ENOSPC; + req = &gd->arch.mtrr_req[gd->arch.mtrr_req_count++]; + req->type = type; + req->start = start; + req->size = size; + debug("%d: type=%d, %08llx %08llx\n", gd->arch.mtrr_req_count - 1, + req->type, req->start, req->size); + mask = ~(req->size - 1); + mask &= (1ULL << CONFIG_CPU_ADDR_BITS) - 1; + mask |= MTRR_PHYS_MASK_VALID; + debug(" %016llx %016llx\n", req->start | req->type, mask); + + return 0; +} -- cgit v1.2.1