x86: Change condition for using CAR

At present we assume that CAR (Cache-as-RAM) is used if HOBs (Hand-off
blocks) are not, since HOBs typically indicate that an FSP is in use, and
FSPs handle the CAR init.

However this is a bit indirect, and for FSP2 machines which use their own
CAR implementation (such as apollolake) but use the FSP for other
functions, the logic is wrong.

To fix this, add a dedicated Kconfig option to indicate when CAR is used.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: fix a typo in the commit message]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/Kconfig

@@ -364,6 +364,14 @@ config HAVE_FSP
 	  Note: Without this binary U-Boot will not be able to set up its
 	  SDRAM so will not boot.
 
+config USE_CAR
+	bool "Use Cache-As-RAM (CAR) to get temporary RAM at start-up"
+	default y if !HAVE_FSP
+	help
+	  Select this option if your board uses CAR init code, typically in a
+	  car.S file, to get some initial memory for code execution. This is
+	  common with Intel CPUs which don't use FSP.
+
 choice
 	prompt "FSP version"
 	depends on HAVE_FSP

arch/x86/cpu/start.S

@@ -90,7 +90,7 @@ early_board_init_ret:
 	jmp	car_init
 .globl car_init_ret
 car_init_ret:
-#ifndef CONFIG_USE_HOB
+#ifdef CONFIG_USE_CAR
 	/*
 	 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
 	 * or fully initialised SDRAM - we really don't care which)
@@ -130,7 +130,7 @@ car_init_ret:
 
 	/* Get address of global_data */
 	mov	%fs:0, %edx
-#ifdef CONFIG_USE_HOB
+#if defined(CONFIG_USE_HOB) && !defined(CONFIG_USE_CAR)
 	/* Store the HOB list if we have one */
 	test	%esi, %esi
 	jz	skip_hob

configs/slimbootloader_defconfig

@@ -18,3 +18,4 @@ CONFIG_REGMAP=y
 CONFIG_SYSCON=y
 # CONFIG_PCI_PNP is not set
 CONFIG_CONSOLE_SCROLL_LINES=5
+# CONFIG_USE_CAR is not set