x86: Support Intel FSP initialization path in start.S

Per Intel FSP architecture specification, FSP provides 3 routines
for bootloader to call. The first one is the TempRamInit (aka
Cache-As-Ram initialization) and the second one is the FspInit
which does the memory bring up (like MRC for other x86 targets)
and chipset initialization. Those two routines have to be called
before U-Boot jumping to board_init_f in start.S.

The FspInit() will return several memory blocks called Hand Off
Blocks (HOBs) whose format is described in Platform Initialization
(PI) specification (part of the UEFI specication) to the bootloader.
Save this HOB address to the U-Boot global data for later use.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>

arch/x86/cpu/start.S

@@ -75,6 +75,7 @@ early_board_init_ret:
 	jmp	car_init
 .globl car_init_ret
 car_init_ret:
+#ifndef CONFIG_HAVE_FSP
 	/*
 	 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
 	 * or fully initialised SDRAM - we really don't care which)
@@ -95,6 +96,12 @@ car_init_ret:
 #ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE
 	subl	$CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp
 #endif
+#else
+	/*
+	 * When we get here after car_init, esp points to a temporary stack
+	 * and esi holds the HOB list address returned by the FSP.
+	 */
+#endif
 
 	/* Reserve space on stack for global data */
 	subl	$GENERATED_GBL_DATA_SIZE, %esp
@@ -109,6 +116,13 @@ car_init_ret:
 	movl	%esp, %edi
 	rep	stosb
 
+#ifdef CONFIG_HAVE_FSP
+	/* Store HOB list */
+	movl	%esp, %edx
+	addl	$GD_HOB_LIST, %edx
+	movl	%esi, (%edx)
+#endif
+
 	/* Setup first parameter to setup_gdt, pointer to global_data */
 	movl	%esp, %eax
 

arch/x86/include/asm/global_data.h

@@ -47,6 +47,9 @@ struct arch_global_data {
 	enum pei_boot_mode_t pei_boot_mode;
 	const struct pch_gpio_map *gpio_map;	/* board GPIO map */
 	struct memory_info meminfo;	/* Memory information */
+#ifdef CONFIG_HAVE_FSP
+	void	*hob_list;		/* FSP HOB list */
+#endif
 };
 
 #endif

arch/x86/lib/asm-offsets.c

@@ -18,5 +18,8 @@
 int main(void)
 {
 	DEFINE(GD_BIST, offsetof(gd_t, arch.bist));
+#ifdef CONFIG_HAVE_FSP
+	DEFINE(GD_HOB_LIST, offsetof(gd_t, arch.hob_list));
+#endif
 	return 0;
 }