summaryrefslogtreecommitdiff
path: root/arch/x86/cpu/mtrr.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/cpu/mtrr.c')
-rw-r--r--arch/x86/cpu/mtrr.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/arch/x86/cpu/mtrr.c b/arch/x86/cpu/mtrr.c
new file mode 100644
index 0000000..d5a825d
--- /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 <common.h>
+#include <asm/io.h>
+#include <asm/msr.h>
+#include <asm/mtrr.h>
+
+/* 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;
+}