[S] Change in coreboot[main]: northbridge/intel/sandybridge: Enable x86_64 for mrc.bin

[Patrick Rudolph (Code Review)]

Attention is currently required from: Angel Pons.

Patrick Rudolph has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/79754?usp=email )

Change subject: northbridge/intel/sandybridge: Enable x86_64 for mrc.bin
......................................................................

northbridge/intel/sandybridge: Enable x86_64 for mrc.bin

Enable x86_64 support for MRC.bin:
- Add a wrapper function for console printing that calls into
  long mode to call native do_putchar
- Remove Kconfig guard for x86_64 when MRC is being used

Tested: Booted Lenovo X220 using mrc.bin under x86_64 and
        MRC is able to print to the console.

Change-Id: I21ffcb5f5d4bf155593e8111531bdf0ed7071dfc
Signed-off-by: Patrick Rudolph 
---
M src/cpu/intel/model_206ax/Kconfig
M src/northbridge/intel/sandybridge/mrc_wrapper.S
M src/northbridge/intel/sandybridge/raminit_mrc.c
3 files changed, 41 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/54/79754/1

diff --git a/src/cpu/intel/model_206ax/Kconfig b/src/cpu/intel/model_206ax/Kconfig
index 10c0ae3..649ef4e 100644
--- a/src/cpu/intel/model_206ax/Kconfig
+++ b/src/cpu/intel/model_206ax/Kconfig
@@ -1,7 +1,7 @@
 config CPU_INTEL_MODEL_206AX
    bool
    select ARCH_X86
-	select HAVE_EXP_X86_64_SUPPORT if USE_NATIVE_RAMINIT
+	select HAVE_EXP_X86_64_SUPPORT
    select SSE2
    select UDELAY_TSC
    select TSC_MONOTONIC_TIMER
diff --git a/src/northbridge/intel/sandybridge/mrc_wrapper.S b/src/northbridge/intel/sandybridge/mrc_wrapper.S
index e169064..c92289c 100644
--- a/src/northbridge/intel/sandybridge/mrc_wrapper.S
+++ b/src/northbridge/intel/sandybridge/mrc_wrapper.S
@@ -26,3 +26,38 @@
    popal
    ret

+	.section ".text.mrc_console_wrapper", "ax", @progbits
+	.globl mrc_console_wrapper
+
+	/*
+	 * Callback for MRC to print a character on the console.
+	 * As MRC is x86_32 call into long mode and use the x86_64
+	 * function do_putchar to print to console.
+	 */
+mrc_console_wrapper:
+	/* Set up new stack frame */
+	pushal
+	mov	%esp, %ebp
+
+	/* Align stack and make space for arguments */
+	andl	$0xfffffff0, %esp
+	subl	$8, %esp
+
+	/* Get argument */
+	movl	36(%ebp), %eax
+	push	%eax
+
+	/* Get function to call */
+	mov	$do_putchar, %eax
+	push	%eax
+
+	/*
+	 * Elevate to long mode. As 2nd and 3rd argument are unused they
+	 * haven't been pushed to the stack.
+	 */
+	call long_mode_call_3arg
+
+	/* Restore stack pointer */
+	mov	%ebp, %esp
+	popal
+	ret
\ No newline at end of file
diff --git a/src/northbridge/intel/sandybridge/raminit_mrc.c b/src/northbridge/intel/sandybridge/raminit_mrc.c
index d59aa86..0bcc817 100644
--- a/src/northbridge/intel/sandybridge/raminit_mrc.c
+++ b/src/northbridge/intel/sandybridge/raminit_mrc.c
@@ -52,6 +52,7 @@

/* Assembly functions: */
 void mrc_wrapper(void *func_ptr, uint32_t arg1);
+void mrc_console_wrapper(uint8_t byte);

static void save_mrc_data(struct pei_data *pei_data)
 {
@@ -155,7 +156,10 @@
    }

/* Pass console handler in pei_data */
-	pei_data->tx_byte_ptr = (uintptr_t)do_putchar;
+	if (ENV_X86_64)
+		pei_data->tx_byte_ptr = (uintptr_t)mrc_console_wrapper;
+	else
+		pei_data->tx_byte_ptr = (uintptr_t)do_putchar;

/* Locate and call UEFI System Agent binary. */
    entry = cbfs_map("mrc.bin", NULL);