stm32f: Preserve flash write protect info across sysjump

This is needed so that we know the flash module is locked up.

Signed-off-by: Vic Yang <victoryang@chromium.org>

BUG=chrome-os-partner:13219
TEST=Check PROTECT_ALL_NOW is still set after sysjump.
BRANCH=snow

Change-Id: I632d671058a49d30addb50744ed791f6b43609f5
Reviewed-on: https://gerrit.chromium.org/gerrit/31544
Reviewed-by: Yung-Chieh Lo <yjlou@chromium.org>
Commit-Ready: Vic Yang <victoryang@chromium.org>
Tested-by: Vic Yang <victoryang@chromium.org>

1 files changed, 32 insertions, 1 deletions

diff --git a/chip/stm32/flash-stm32f100.c b/chip/stm32/flash-stm32f100.c
index 4c9c39b8b8..2d2b3647b3 100644
--- a/chip/stm32/flash-stm32f100.c
+++ b/chip/stm32/flash-stm32f100.c
@@ -7,6 +7,7 @@
 
 #include "console.h"
 #include "flash.h"
+#include "hooks.h"
 #include "registers.h"
 #include "panic.h"
 #include "power_button.h"
@@ -74,6 +75,13 @@ struct persist_state {
 /* Flag indicating whether we have locked down entire flash */
 static int entire_flash_locked;
 
+#define FLASH_SYSJUMP_TAG 0x5750 /* "WP" - Write Protect */
+#define FLASH_HOOK_VERSION 1
+/* The previous write protect state before sys jump */
+struct flash_wp_state {
+	int entire_flash_locked;
+};
+
 /* Functions defined in system.c to access backup registers */
 int system_set_fake_wp(int val);
 int system_get_fake_wp(void);
@@ -528,13 +536,21 @@ int flash_pre_init(void)
 	uint32_t reset_flags = system_get_reset_flags();
 	uint32_t prot_flags = flash_get_protect();
 	int need_reset = 0;
+	const struct flash_wp_state *prev;
+	int version, size;
 
 	/*
 	 * If we have already jumped between images, an earlier image could
 	 * have applied write protection. Nothing additional needs to be done.
 	 */
-	if (reset_flags & RESET_FLAG_SYSJUMP)
+	if (reset_flags & RESET_FLAG_SYSJUMP) {
+		prev = (const struct flash_wp_state *)system_get_jump_tag(
+				FLASH_SYSJUMP_TAG, &version, &size);
+		if (prev && version == FLASH_HOOK_VERSION &&
+		    size == sizeof(*prev))
+			entire_flash_locked = prev->entire_flash_locked;
 		return EC_SUCCESS;
+	}
 
 	if (prot_flags & EC_FLASH_PROTECT_GPIO_ASSERTED) {
 		if ((prot_flags & EC_FLASH_PROTECT_RO_AT_BOOT) &&
@@ -676,3 +692,18 @@ DECLARE_CONSOLE_COMMAND(fakewp, command_set_fake_wp,
 			"<0 | 1>",
 			"Set fake write protect pin",
 			NULL);
+
+/*****************************************************************************/
+/* Hooks */
+
+static int flash_preserve_state(void)
+{
+	struct flash_wp_state state;
+
+	state.entire_flash_locked = entire_flash_locked;
+
+	system_add_jump_tag(FLASH_SYSJUMP_TAG, FLASH_HOOK_VERSION,
+			    sizeof(state), &state);
+	return EC_SUCCESS;
+}
+DECLARE_HOOK(HOOK_SYSJUMP, flash_preserve_state, HOOK_PRIO_DEFAULT);