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 <sjg@chromium.org>

4 files changed, 98 insertions, 18 deletions

diff --git a/arch/x86/cpu/Makefile b/arch/x86/cpu/Makefile
index 5033d2b757..62e43c04e5 100644
--- a/arch/x86/cpu/Makefile
+++ b/arch/x86/cpu/Makefile
@@ -17,5 +17,6 @@ obj-$(CONFIG_NORTHBRIDGE_INTEL_SANDYBRIDGE) += ivybridge/
 obj-$(CONFIG_NORTHBRIDGE_INTEL_IVYBRIDGE) += ivybridge/
 obj-$(CONFIG_INTEL_QUEENSBAY) += queensbay/
 obj-y += lapic.o
+obj-y += mtrr.o
 obj-$(CONFIG_PCI) += pci.o
 obj-y += turbo.o
diff --git a/arch/x86/cpu/coreboot/coreboot.c b/arch/x86/cpu/coreboot/coreboot.c
index cfacc05875..6d06d5af19 100644
--- a/arch/x86/cpu/coreboot/coreboot.c
+++ b/arch/x86/cpu/coreboot/coreboot.c
@@ -15,6 +15,7 @@
 #include <asm/cache.h>
 #include <asm/cpu.h>
 #include <asm/io.h>
+#include <asm/mtrr.h>
 #include <asm/arch/tables.h>
 #include <asm/arch/sysinfo.h>
 #include <asm/arch/timestamp.h>
@@ -64,11 +65,6 @@ int board_eth_init(bd_t *bis)
 	return pci_eth_init(bis);
 }
 
-#define MTRR_TYPE_WP          5
-#define MTRRcap_MSR           0xfe
-#define MTRRphysBase_MSR(reg) (0x200 + 2 * (reg))
-#define MTRRphysMask_MSR(reg) (0x200 + 2 * (reg) + 1)
-
 void board_final_cleanup(void)
 {
 	/* Un-cache the ROM so the kernel has one
@@ -77,15 +73,17 @@ void board_final_cleanup(void)
 	 * Coreboot should have assigned this to the
 	 * top available variable MTRR.
 	 */
-	u8 top_mtrr = (native_read_msr(MTRRcap_MSR) & 0xff) - 1;
-	u8 top_type = native_read_msr(MTRRphysBase_MSR(top_mtrr)) & 0xff;
+	u8 top_mtrr = (native_read_msr(MTRR_CAP_MSR) & 0xff) - 1;
+	u8 top_type = native_read_msr(MTRR_PHYS_BASE_MSR(top_mtrr)) & 0xff;
 
 	/* Make sure this MTRR is the correct Write-Protected type */
-	if (top_type == MTRR_TYPE_WP) {
-		disable_caches();
-		wrmsrl(MTRRphysBase_MSR(top_mtrr), 0);
-		wrmsrl(MTRRphysMask_MSR(top_mtrr), 0);
-		enable_caches();
+	if (top_type == MTRR_TYPE_WRPROT) {
+		struct mtrr_state state;
+
+		mtrr_open(&state);
+		wrmsrl(MTRR_PHYS_BASE_MSR(top_mtrr), 0);
+		wrmsrl(MTRR_PHYS_MASK_MSR(top_mtrr), 0);
+		mtrr_close(&state);
 	}
 
 	/* Issue SMI to Coreboot to lock down ME and registers */
diff --git a/arch/x86/cpu/ivybridge/car.S b/arch/x86/cpu/ivybridge/car.S
index dca68e4144..72b22ea9e4 100644
--- a/arch/x86/cpu/ivybridge/car.S
+++ b/arch/x86/cpu/ivybridge/car.S
@@ -61,7 +61,7 @@ clear_mtrrs:
 
 	post_code(POST_CAR_MTRR)
 	/* Configure the default memory type to uncacheable */
-	movl	$MTRRdefType_MSR, %ecx
+	movl	$MTRR_DEF_TYPE_MSR, %ecx
 	rdmsr
 	andl	$(~0x00000cff), %eax
 	wrmsr
@@ -76,16 +76,16 @@ clear_mtrrs:
 	post_code(POST_CAR_BASE_ADDRESS)
 	/* Set Cache-as-RAM mask */
 	movl	$(MTRR_PHYS_MASK_MSR(0)), %ecx
-	movl	$(~(CACHE_AS_RAM_SIZE - 1) | MTRRphysMaskValid), %eax
+	movl	$(~(CACHE_AS_RAM_SIZE - 1) | MTRR_PHYS_MASK_VALID), %eax
 	movl	$CPU_PHYSMASK_HI, %edx
 	wrmsr
 
 	post_code(POST_CAR_MASK)
 
 	/* Enable MTRR */
-	movl	$MTRRdefType_MSR, %ecx
+	movl	$MTRR_DEF_TYPE_MSR, %ecx
 	rdmsr
-	orl	$MTRRdefTypeEn, %eax
+	orl	$MTRR_DEF_TYPE_EN, %eax
 	wrmsr
 
 	/* Enable cache (CR0.CD = 0, CR0.NW = 0) */
@@ -130,7 +130,7 @@ clear_mtrrs:
 
 	movl	$MTRR_PHYS_MASK_MSR(1), %ecx
 	movl	$CPU_PHYSMASK_HI, %edx
-	movl	$(~(CONFIG_XIP_ROM_SIZE - 1) | MTRRphysMaskValid), %eax
+	movl	$(~(CONFIG_XIP_ROM_SIZE - 1) | MTRR_PHYS_MASK_VALID), %eax
 	wrmsr
 
 	post_code(POST_CAR_ROM_CACHE)
@@ -141,7 +141,7 @@ clear_mtrrs:
 	xorl	%edx, %edx
 	wrmsr
 	movl	$MTRR_PHYS_MASK_MSR(2), %ecx
-	movl	$(CACHE_MRC_MASK | MTRRphysMaskValid), %eax
+	movl	$(CACHE_MRC_MASK | MTRR_PHYS_MASK_VALID), %eax
 	movl	$CPU_PHYSMASK_HI, %edx
 	wrmsr
 #endif
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 <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;
+}