diff --git a/chip/stm32/flash-stm32f100.c b/chip/stm32/flash-stm32f100.c
index 50f1a5b0f3..e5f11d9394 100644
--- a/chip/stm32/flash-stm32f100.c
+++ b/chip/stm32/flash-stm32f100.c
@@ -8,6 +8,7 @@
 #include "console.h"
 #include "flash.h"
 #include "registers.h"
+#include "power_button.h"
 #include "task.h"
 #include "timer.h"
 #include "util.h"
@@ -39,6 +40,10 @@
 #define PRG_LOCK 0
 #define OPT_LOCK (1<<9)
 
+/* Fake write protect switch for flash write protect development.
+ * TODO: Remove this when we have real write protect pin. */
+static int fake_write_protect;
+
 static void write_optb(int byte, uint8_t value);
 
 int flash_physical_size(void)
@@ -123,7 +128,7 @@ static void preserve_optb(int byte)
 	uint8_t optb[8];
 
 	/* The byte has been reset, no need to run preserve. */
-	if (*(uint8_t *)(STM32_OPTB_BASE + byte) == 0xff)
+	if (*(uint16_t *)(STM32_OPTB_BASE + byte) == 0xffff)
 		return;
 
 	for (i = 0; i < ARRAY_SIZE(optb); ++i)
@@ -295,15 +300,61 @@ int flash_physical_get_protect(int block)
 void flash_physical_set_protect(int start_bank, int bank_count)
 {
 	int block;
+	int i;
+	int original_val[8], val[8];
+
+	for (i = 0; i < 8; ++i)
+		original_val[i] = val[i] = read_optb(i * 2);
 
 	for (block = start_bank; block < start_bank + bank_count; block++) {
-		int byte_off = STM32_OPTB_WRP_OFF(block/8);
-		uint8_t val = read_optb(byte_off) | (1 << (block % 8));
-		write_optb(byte_off, val);
+		int byte_off = STM32_OPTB_WRP_OFF(block/8) / 2;
+		val[byte_off] = val[byte_off] & (~(1 << (block % 8)));
 	}
+
+	for (i = 0; i < 8; ++i)
+		if (original_val[i] != val[i])
+			write_optb(i * 2, val[i]);
+}
+
+static void unprotect_all_blocks(void)
+{
+	int i;
+	for (i = 4; i < 8; ++i)
+		write_optb(i * 2, 0xff);
 }
 
 int flash_physical_pre_init(void)
 {
+	/* Drop write protect status here. If a block should be protected,
+	 * write protect for it will be set by pstate. */
+	unprotect_all_blocks();
+
 	return EC_SUCCESS;
 }
+
+int write_protect_asserted(void)
+{
+	return fake_write_protect;
+}
+
+static int command_set_fake_wp(int argc, char **argv)
+{
+	int val;
+	char *e;
+
+	if (argc < 2)
+		return EC_ERROR_PARAM_COUNT;
+
+	val = strtoi(argv[1], &e, 0);
+	if (*e)
+		return EC_ERROR_PARAM1;
+
+	fake_write_protect = val;
+	ccprintf("Fake write protect = %d\n", val);
+
+	return EC_SUCCESS;
+}
+DECLARE_CONSOLE_COMMAND(fakewp, command_set_fake_wp,
+			"<0 | 1>",
+			"Set fake write protect pin",
+			NULL);
diff --git a/common/flash_common.c b/common/flash_common.c
index c914d52672..bfd50edac5 100644
--- a/common/flash_common.c
+++ b/common/flash_common.c
@@ -20,13 +20,12 @@
 #define PHYSICAL_BANKS (CONFIG_FLASH_PHYSICAL_SIZE / CONFIG_FLASH_BANK_SIZE)
 
 /* Persistent protection state flash offset / size / bank */
-#define PSTATE_OFFSET (CONFIG_SECTION_FLASH_PSTATE_OFF - CONFIG_FLASH_BASE)
+#define PSTATE_OFFSET CONFIG_SECTION_FLASH_PSTATE_OFF
 #define PSTATE_SIZE   CONFIG_SECTION_FLASH_PSTATE_SIZE
 #define PSTATE_BANK   (PSTATE_OFFSET / CONFIG_FLASH_BANK_SIZE)
 
 /* Read-only firmware offset and size in units of flash banks */
-#define RO_BANK_OFFSET ((CONFIG_SECTION_RO_OFF - CONFIG_FLASH_BASE) \
-			/ CONFIG_FLASH_BANK_SIZE)
+#define RO_BANK_OFFSET (CONFIG_SECTION_RO_OFF / CONFIG_FLASH_BANK_SIZE)
 #define RO_BANK_COUNT  (CONFIG_SECTION_RO_SIZE / CONFIG_FLASH_BANK_SIZE)
 
 
@@ -50,7 +49,10 @@ static int wp_pin_asserted(void)
 {
 #ifdef BOARD_link
 	return write_protect_asserted();
-#elif defined(CHIP_stm32)
+#elif defined(CHIP_VARIANT_stm32f100)
+	/* Fake write protect pin */
+	return write_protect_asserted();
+#elif defined(CHIP_STM32)
 	/* TODO (vpalatin) : write protect scheme for stm32 */
 	/*
 	 * Always enable write protect until we have WP pin.  For developer to
diff --git a/include/flash.h b/include/flash.h
index 617259f0c9..d74ae19c7b 100644
--- a/include/flash.h
+++ b/include/flash.h
@@ -9,6 +9,7 @@
 #define __CROS_EC_FLASH_H
 
 #include "common.h"
+#include "config.h"
 #include "ec_commands.h"  /* For EC_FLASH_PROTECT_* flags */
 
 /*****************************************************************************/
@@ -41,7 +42,7 @@ int flash_physical_size(void);
  */
 static inline char *flash_physical_dataptr(int offset)
 {
-	return (char *)offset;
+	return (char *)(CONFIG_FLASH_BASE + offset);
 }
 
 /**