u-boot/arch/x86/cpu/mtrr.c
Simon Glass add3f4c918 x86: Add a function to set variable MTRRs
Normally U-Boot handles MTRRs through an add/commit process which
overwrites all MTRRs. But in very early boot it is not desirable to clear
the existing MTRRs since they may be in use and it can cause a hang.

Add a new mtrr_set_next_var() function which sets up the next available
MTRR to the required region.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: pass 'type' to set_var_mtrr() in mtrr_set_next_var()]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
2019-10-08 13:57:48 +08:00

152 lines
3.5 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2014 Google, Inc
*
* 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
*/
/*
* Note that any console output (e.g. debug()) in this file will likely fail
* since the MTRR registers are sometimes in flux.
*/
#include <common.h>
#include <asm/io.h>
#include <asm/msr.h>
#include <asm/mtrr.h>
DECLARE_GLOBAL_DATA_PTR;
/* Prepare to adjust MTRRs */
void mtrr_open(struct mtrr_state *state, bool do_caches)
{
if (!gd->arch.has_mtrr)
return;
if (do_caches) {
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, bool do_caches)
{
if (!gd->arch.has_mtrr)
return;
wrmsrl(MTRR_DEF_TYPE_MSR, state->deftype | MTRR_DEF_TYPE_EN);
if (do_caches && state->enable_cache)
enable_caches();
}
static void set_var_mtrr(uint reg, uint type, uint64_t start, uint64_t size)
{
u64 mask;
wrmsrl(MTRR_PHYS_BASE_MSR(reg), start | type);
mask = ~(size - 1);
mask &= (1ULL << CONFIG_CPU_ADDR_BITS) - 1;
wrmsrl(MTRR_PHYS_MASK_MSR(reg), mask | MTRR_PHYS_MASK_VALID);
}
int mtrr_commit(bool do_caches)
{
struct mtrr_request *req = gd->arch.mtrr_req;
struct mtrr_state state;
int i;
debug("%s: enabled=%d, count=%d\n", __func__, gd->arch.has_mtrr,
gd->arch.mtrr_req_count);
if (!gd->arch.has_mtrr)
return -ENOSYS;
debug("open\n");
mtrr_open(&state, do_caches);
debug("open done\n");
for (i = 0; i < gd->arch.mtrr_req_count; i++, req++)
set_var_mtrr(i, req->type, req->start, req->size);
/* Clear the ones that are unused */
debug("clear\n");
for (; i < MTRR_COUNT; i++)
wrmsrl(MTRR_PHYS_MASK_MSR(i), 0);
debug("close\n");
mtrr_close(&state, do_caches);
debug("mtrr done\n");
return 0;
}
int mtrr_add_request(int type, uint64_t start, uint64_t size)
{
struct mtrr_request *req;
uint64_t mask;
debug("%s: count=%d\n", __func__, gd->arch.mtrr_req_count);
if (!gd->arch.has_mtrr)
return -ENOSYS;
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;
}
static int get_var_mtrr_count(void)
{
return msr_read(MSR_MTRR_CAP_MSR).lo & MSR_MTRR_CAP_VCNT;
}
static int get_free_var_mtrr(void)
{
struct msr_t maskm;
int vcnt;
int i;
vcnt = get_var_mtrr_count();
/* Identify the first var mtrr which is not valid */
for (i = 0; i < vcnt; i++) {
maskm = msr_read(MTRR_PHYS_MASK_MSR(i));
if ((maskm.lo & MTRR_PHYS_MASK_VALID) == 0)
return i;
}
/* No free var mtrr */
return -ENOSPC;
}
int mtrr_set_next_var(uint type, uint64_t start, uint64_t size)
{
int mtrr;
mtrr = get_free_var_mtrr();
if (mtrr < 0)
return mtrr;
set_var_mtrr(mtrr, type, start, size);
debug("MTRR %x: start=%x, size=%x\n", mtrr, (uint)start, (uint)size);
return 0;
}