soc/mediatek: Add EARLY_MMU_INIT kconfig option

Accessing RAM before mmu initialized is time consuming. During mmu
initialization, `mmu_init()` and `mmu_config_range()` write logs to the
console buffer and contribue the extra boot time.

This patch adds a kconfig option to move `mtk_mmu_init()` to
`bootblock_soc_early_init()`. When `EARLY_MMU_INIT` is enabled, mmu is
initialized before `console_init()` ready. So `mmu_init()` and
`mmu_config_range()` won't write logs to the console buffer and save the
boot time.

It saves about 65ms on Geralt with EARLY_MMU_INIT enabled.

Before:
   0:1st timestamp                                     239,841 (0)
  11:start of bootblock                                239,920 (79)
  12:end of bootblock                                  323,191 (83,271)

After:
   0:1st timestamp                                     239,804 (0)
  11:start of bootblock                                239,884 (80)
  12:end of bootblock                                  258,846 (18,962)

BUG=b:320381143
TEST=check timestamps in cbmem

Change-Id: I7f4c3c6c836f7276119698c6de362794cf4222a6
Signed-off-by: Yidi Lin <yidilin@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79990
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

src/soc/mediatek/common/Kconfig

@@ -91,4 +91,11 @@ config DEVAPC_DEBUG
 	  When this option is enabled, the DEVAPC driver prints the settings after
 	  initialization.
 
+config EARLY_MMU_INIT
+	bool
+	default n
+	help
+	  When this option is enabled, `mtk_mmu_init()` will be done in
+	  `bootblock_soc_early_init()` to reduce the boot time.
+
 endif

src/soc/mediatek/common/bootblock.c

@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <bootblock_common.h>
+#include <soc/mmu_operations.h>
+
+void bootblock_soc_early_init(void)
+{
+	if (CONFIG(EARLY_MMU_INIT))
+		mtk_mmu_init();
+}

src/soc/mediatek/common/mmu_operations.c

@@ -9,6 +9,13 @@ __weak void mtk_soc_after_dram(void) { /* do nothing */ }
 
 void mtk_mmu_init(void)
 {
+	static bool mmu_inited;
+
+	if (mmu_inited)
+		return;
+
+	mmu_inited = true;
+
 	mmu_init();
 
 	/*

src/soc/mediatek/mt8188/Makefile.inc

@@ -9,7 +9,7 @@ all-$(CONFIG_SPI_FLASH) += ../common/spi.c spi.c
 all-y += timer.c ../common/timer_prepare.c
 all-y += ../common/uart.c
 
-bootblock-y += bootblock.c
+bootblock-y += ../common/bootblock.c bootblock.c
 bootblock-y += ../common/eint_event.c
 bootblock-y += ../common/lastbus_v2.c lastbus.c
 bootblock-y += ../common/mmu_operations.c