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>

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

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 */

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

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;
+}

arch/x86/include/asm/global_data.h

@@ -29,6 +29,19 @@ struct memory_info {
 	struct memory_area area[CONFIG_NR_DRAM_BANKS];
 };
 
+#define MAX_MTRR_REQUESTS	8
+
+/**
+ * A request for a memory region to be set up in a particular way. These
+ * requests are processed before board_init_r() is called. They are generally
+ * optional and can be ignored with some performance impact.
+ */
+struct mtrr_request {
+	int type;		/* MTRR_TYPE_... */
+	uint64_t start;
+	uint64_t size;
+};
+
 /* Architecture-specific global data */
 struct arch_global_data {
 	struct global_data *gd_addr;		/* Location of Global Data */
@@ -49,6 +62,8 @@ struct arch_global_data {
 #ifdef CONFIG_HAVE_FSP
 	void	*hob_list;		/* FSP HOB list */
 #endif
+	struct mtrr_request mtrr_req[MAX_MTRR_REQUESTS];
+	int mtrr_req_count;
 };
 
 #endif

arch/x86/include/asm/mtrr.h

@@ -9,94 +9,85 @@
 #ifndef _ASM_MTRR_H
 #define _ASM_MTRR_H
 
-/*  These are the region types  */
-#define MTRR_TYPE_UNCACHEABLE 0
-#define MTRR_TYPE_WRCOMB     1
-/*#define MTRR_TYPE_         2*/
-/*#define MTRR_TYPE_         3*/
-#define MTRR_TYPE_WRTHROUGH  4
-#define MTRR_TYPE_WRPROT     5
-#define MTRR_TYPE_WRBACK     6
-#define MTRR_NUM_TYPES       7
-
-#define MTRRcap_MSR     0x0fe
-#define MTRRdefType_MSR 0x2ff
-
-#define MTRRdefTypeEn		(1 << 11)
-#define MTRRdefTypeFixEn	(1 << 10)
-
-#define SMRRphysBase_MSR 0x1f2
-#define SMRRphysMask_MSR 0x1f3
-
-#define MTRRphysBase_MSR(reg) (0x200 + 2 * (reg))
-#define MTRRphysMask_MSR(reg) (0x200 + 2 * (reg) + 1)
-
-#define MTRRphysMaskValid	(1 << 11)
-
-#define NUM_FIXED_RANGES 88
-#define RANGES_PER_FIXED_MTRR 8
-#define MTRRfix64K_00000_MSR 0x250
-#define MTRRfix16K_80000_MSR 0x258
-#define MTRRfix16K_A0000_MSR 0x259
-#define MTRRfix4K_C0000_MSR 0x268
-#define MTRRfix4K_C8000_MSR 0x269
-#define MTRRfix4K_D0000_MSR 0x26a
-#define MTRRfix4K_D8000_MSR 0x26b
-#define MTRRfix4K_E0000_MSR 0x26c
-#define MTRRfix4K_E8000_MSR 0x26d
-#define MTRRfix4K_F0000_MSR 0x26e
-#define MTRRfix4K_F8000_MSR 0x26f
+/* MTRR region types */
+#define MTRR_TYPE_UNCACHEABLE	0
+#define MTRR_TYPE_WRCOMB	1
+#define MTRR_TYPE_WRTHROUGH	4
+#define MTRR_TYPE_WRPROT	5
+#define MTRR_TYPE_WRBACK	6
+
+#define MTRR_TYPE_COUNT		7
+
+#define MTRR_CAP_MSR		0x0fe
+#define MTRR_DEF_TYPE_MSR	0x2ff
+
+#define MTRR_DEF_TYPE_EN	(1 << 11)
+#define MTRR_DEF_TYPE_FIX_EN	(1 << 10)
+
+#define MTRR_PHYS_BASE_MSR(reg)	(0x200 + 2 * (reg))
+#define MTRR_PHYS_MASK_MSR(reg)	(0x200 + 2 * (reg) + 1)
+
+#define MTRR_PHYS_MASK_VALID	(1 << 11)
+
+#define MTRR_BASE_TYPE_MASK	0x7
+
+/* Number of MTRRs supported */
+#define MTRR_COUNT		8
 
 #if !defined(__ASSEMBLER__)
 
-/*
- * The MTRR code has some side effects that the callers should be aware for.
- * 1. The call sequence matters. x86_setup_mtrrs() calls
- *    x86_setup_fixed_mtrrs_no_enable() then enable_fixed_mtrrs() (equivalent
- *    of x86_setup_fixed_mtrrs()) then x86_setup_var_mtrrs(). If the callers
- *    want to call the components of x86_setup_mtrrs() because of other
- *    rquirements the ordering should still preserved.
- * 2. enable_fixed_mtrr() will enable both variable and fixed MTRRs because
- *    of the nature of the global MTRR enable flag. Therefore, all direct
- *    or indirect callers of enable_fixed_mtrr() should ensure that the
- *    variable MTRR MSRs do not contain bad ranges.
- * 3. If CONFIG_CACHE_ROM is selected an MTRR is allocated for enabling
- *    the caching of the ROM. However, it is set to uncacheable (UC). It
- *    is the responsiblity of the caller to enable it by calling
- *    x86_mtrr_enable_rom_caching().
+/**
+ * Information about the previous MTRR state, set up by mtrr_open()
+ *
+ * @deftype:		Previous value of MTRR_DEF_TYPE_MSR
+ * @enable_cache:	true if cache was enabled
  */
-void x86_setup_mtrrs(void);
-/*
- * x86_setup_var_mtrrs() parameters:
- * address_bits - number of physical address bits supported by cpu
- * above4gb - 2 means dynamically detect number of variable MTRRs available.
- *            non-zero means handle memory ranges above 4GiB.
- *            0 means ignore memory ranges above 4GiB
+struct mtrr_state {
+	uint64_t deftype;
+	bool enable_cache;
+};
+
+/**
+ * mtrr_open() - Prepare to adjust MTRRs
+ *
+ * Use mtrr_open() passing in a structure - this function will init it. Then
+ * when done, pass the same structure to mtrr_close() to re-enable MTRRs and
+ * possibly the cache.
+ *
+ * @state:	Empty structure to pass in to hold settings
+ */
+void mtrr_open(struct mtrr_state *state);
+
+/**
+ * mtrr_open() - Clean up after adjusting MTRRs, and enable them
+ *
+ * This uses the structure containing information returned from mtrr_open().
+ *
+ * @state:	Structure from mtrr_open()
+ */
+/*  */
+void mtrr_close(struct mtrr_state *state);
+
+/**
+ * mtrr_add_request() - Add a new MTRR request
+ *
+ * This adds a request for a memory region to be set up in a particular way.
+ *
+ * @type:	Requested type (MTRR_TYPE_)
+ * @start:	Start address
+ * @size:	Size
+ */
+int mtrr_add_request(int type, uint64_t start, uint64_t size);
+
+/**
+ * mtrr_commit() - set up the MTRR registers based on current requests
+ *
+ * This sets up MTRRs for the available DRAM and the requests received so far.
+ * It must be called with caches disabled.
+ *
+ * @do_caches:	true if caches are currently on
  */
-void x86_setup_var_mtrrs(unsigned int address_bits, unsigned int above4gb);
-void enable_fixed_mtrr(void);
-void x86_setup_fixed_mtrrs(void);
-/* Set up fixed MTRRs but do not enable them. */
-void x86_setup_fixed_mtrrs_no_enable(void);
-int x86_mtrr_check(void);
-/* ROM caching can be used after variable MTRRs are set up. Beware that
- * enabling CONFIG_CACHE_ROM will eat through quite a few MTRRs based on
- * one's IO hole size and WRCOMB resources. Be sure to check the console
- * log when enabling CONFIG_CACHE_ROM or adding WRCOMB resources. Beware that
- * on CPUs with core-scoped MTRR registers such as hyperthreaded CPUs the
- * rom caching will be disabled if all threads run the MTRR code. Therefore,
- * one needs to call x86_mtrr_enable_rom_caching() after all threads of the
- * same core have run the MTRR code. */
-#if CONFIG_CACHE_ROM
-void x86_mtrr_enable_rom_caching(void);
-void x86_mtrr_disable_rom_caching(void);
-/* Return the variable range MTRR index of the ROM cache. */
-long x86_mtrr_rom_cache_var_index(void);
-#else
-static inline void x86_mtrr_enable_rom_caching(void) {}
-static inline void x86_mtrr_disable_rom_caching(void) {}
-static inline long x86_mtrr_rom_cache_var_index(void) { return -1; }
-#endif /* CONFIG_CACHE_ROM */
+int mtrr_commit(bool do_caches);
 
 #endif