x86: chromebook_link: Implement CAR support (cache as RAM)

Add support for CAR so that we have memory to use prior to DRAM init.
On link there is a total of 128KB of CAR available, although some is
used for the memory reference code.

Signed-off-by: Simon Glass <sjg@chromium.org>

2 files changed, 162 insertions, 2 deletions

diff --git a/arch/x86/cpu/ivybridge/car.S b/arch/x86/cpu/ivybridge/car.S
index 0480813..dca68e4 100644
--- a/arch/x86/cpu/ivybridge/car.S
+++ b/arch/x86/cpu/ivybridge/car.S
@@ -12,9 +12,167 @@
  */
 
 #include <common.h>
+#include <asm/mtrr.h>
+#include <asm/post.h>
+#include <asm/processor-flags.h>
 
-	/* Note: ebp must not be touched in this code */
+#define MTRR_PHYS_BASE_MSR(reg) (0x200 + 2 * (reg))
+#define MTRR_PHYS_MASK_MSR(reg) (0x200 + 2 * (reg) + 1)
+
+#define CACHE_AS_RAM_SIZE	CONFIG_DCACHE_RAM_SIZE
+#define CACHE_AS_RAM_BASE	CONFIG_DCACHE_RAM_BASE
+
+/* Cache 4GB - MRC_SIZE_KB for MRC */
+#define CACHE_MRC_BYTES	((CONFIG_CACHE_MRC_SIZE_KB << 10) - 1)
+#define CACHE_MRC_BASE		(0xFFFFFFFF - CACHE_MRC_BYTES)
+#define CACHE_MRC_MASK		(~CACHE_MRC_BYTES)
+
+#define CPU_PHYSMASK_HI	(1 << (CONFIG_CPU_ADDR_BITS - 32) - 1)
+
+#define NOEVICTMOD_MSR	0x2e0
+
+	/*
+	 * Note: ebp must not be touched in this code as it holds the BIST
+	 * value (built-in self test). We preserve this value until it can
+	 * be written to global_data when CAR is ready for use.
+	 */
 .globl car_init
 car_init:
-	/* TODO: Add cache-as-RAM init here */
+	post_code(POST_CAR_START)
+
+	/* Send INIT IPI to all excluding ourself */
+	movl	$0x000C4500, %eax
+	movl	$0xFEE00300, %esi
+	movl	%eax, (%esi)
+
+	post_code(POST_CAR_SIPI)
+	/* Zero out all fixed range and variable range MTRRs */
+	movl	$mtrr_table, %esi
+	movl	$((mtrr_table_end - mtrr_table) / 2), %edi
+	xorl	%eax, %eax
+	xorl	%edx, %edx
+clear_mtrrs:
+	movw	(%esi), %bx
+	movzx	%bx, %ecx
+	wrmsr
+	add	$2, %esi
+	dec	%edi
+	jnz	clear_mtrrs
+
+	post_code(POST_CAR_MTRR)
+	/* Configure the default memory type to uncacheable */
+	movl	$MTRRdefType_MSR, %ecx
+	rdmsr
+	andl	$(~0x00000cff), %eax
+	wrmsr
+
+	post_code(POST_CAR_UNCACHEABLE)
+	/* Set Cache-as-RAM base address */
+	movl	$(MTRR_PHYS_BASE_MSR(0)), %ecx
+	movl	$(CACHE_AS_RAM_BASE | MTRR_TYPE_WRBACK), %eax
+	xorl	%edx, %edx
+	wrmsr
+
+	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	$CPU_PHYSMASK_HI, %edx
+	wrmsr
+
+	post_code(POST_CAR_MASK)
+
+	/* Enable MTRR */
+	movl	$MTRRdefType_MSR, %ecx
+	rdmsr
+	orl	$MTRRdefTypeEn, %eax
+	wrmsr
+
+	/* Enable cache (CR0.CD = 0, CR0.NW = 0) */
+        movl	%cr0, %eax
+	andl	$(~(X86_CR0_CD | X86_CR0_NW)), %eax
+	invd
+	movl	%eax, %cr0
+
+	/* enable the 'no eviction' mode */
+	movl    $NOEVICTMOD_MSR, %ecx
+	rdmsr
+	orl     $1, %eax
+	andl    $~2, %eax
+	wrmsr
+
+       /* Clear the cache memory region. This will also fill up the cache */
+	movl	$CACHE_AS_RAM_BASE, %esi
+	movl	%esi, %edi
+	movl	$(CACHE_AS_RAM_SIZE / 4), %ecx
+	xorl	%eax, %eax
+	rep	stosl
+
+	/* enable the 'no eviction run' state */
+	movl    $NOEVICTMOD_MSR, %ecx
+	rdmsr
+	orl     $3, %eax
+	wrmsr
+
+	post_code(POST_CAR_FILL)
+	/* Enable Cache-as-RAM mode by disabling cache */
+	movl	%cr0, %eax
+	orl	$X86_CR0_CD, %eax
+	movl	%eax, %cr0
+
+	/* Enable cache for our code in Flash because we do XIP here */
+	movl	$MTRR_PHYS_BASE_MSR(1), %ecx
+	xorl	%edx, %edx
+	movl    $car_init_ret, %eax
+	andl    $(~(CONFIG_XIP_ROM_SIZE - 1)), %eax
+	orl	$MTRR_TYPE_WRPROT, %eax
+	wrmsr
+
+	movl	$MTRR_PHYS_MASK_MSR(1), %ecx
+	movl	$CPU_PHYSMASK_HI, %edx
+	movl	$(~(CONFIG_XIP_ROM_SIZE - 1) | MTRRphysMaskValid), %eax
+	wrmsr
+
+	post_code(POST_CAR_ROM_CACHE)
+#ifdef CONFIG_CACHE_MRC_BIN
+	/* Enable caching for ram init code to run faster */
+	movl	$MTRR_PHYS_BASE_MSR(2), %ecx
+	movl	$(CACHE_MRC_BASE | MTRR_TYPE_WRPROT), %eax
+	xorl	%edx, %edx
+	wrmsr
+	movl	$MTRR_PHYS_MASK_MSR(2), %ecx
+	movl	$(CACHE_MRC_MASK | MTRRphysMaskValid), %eax
+	movl	$CPU_PHYSMASK_HI, %edx
+	wrmsr
+#endif
+
+	post_code(POST_CAR_MRC_CACHE)
+	/* Enable cache */
+	movl	%cr0, %eax
+	andl	$(~(X86_CR0_CD | X86_CR0_NW)), %eax
+	movl	%eax, %cr0
+
+	post_code(POST_CAR_CPU_CACHE)
+
+	/* All CPUs need to be in Wait for SIPI state */
+wait_for_sipi:
+	movl	(%esi), %eax
+	bt	$12, %eax
+	jc	wait_for_sipi
+
+	/* return */
 	jmp	car_init_ret
+
+mtrr_table:
+	/* Fixed MTRRs */
+	.word 0x250, 0x258, 0x259
+	.word 0x268, 0x269, 0x26A
+	.word 0x26B, 0x26C, 0x26D
+	.word 0x26E, 0x26F
+	/* Variable MTRRs */
+	.word 0x200, 0x201, 0x202, 0x203
+	.word 0x204, 0x205, 0x206, 0x207
+	.word 0x208, 0x209, 0x20A, 0x20B
+	.word 0x20C, 0x20D, 0x20E, 0x20F
+	.word 0x210, 0x211, 0x212, 0x213
+mtrr_table_end:
diff --git a/arch/x86/cpu/ivybridge/cpu.c b/arch/x86/cpu/ivybridge/cpu.c
index 1cbdaaf..5863811 100644
--- a/arch/x86/cpu/ivybridge/cpu.c
+++ b/arch/x86/cpu/ivybridge/cpu.c
@@ -12,6 +12,7 @@
 
 #include <common.h>
 #include <asm/cpu.h>
+#include <asm/post.h>
 #include <asm/processor.h>
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -20,6 +21,7 @@ int arch_cpu_init(void)
 {
 	int ret;
 
+	post_code(POST_CPU_INIT);
 	timer_set_base(rdtsc());
 
 	ret = x86_cpu_init_f();