EFS: Switch active slot when current slot is invalid

When EFS finds the active slot is invalid, it tries the other slot.
This patch makes the other slot active so that the following boots
will try the other slot first.

This patch also replaces enum flash_rw_slot with system_image_copy_t.
The new APIs are therefore renamed from *_slot to *_copy. Basically,
this makes vboot see slots as a conceptual place instead of physical
spaces bound to flash storage.

BUG=b:65028930
BRANCH=none
TEST=On Fizz, verify:
1. RW_B is old and updated by soft sync. RW_B is activated and
   executed after reboot. System continues to boot to OS.
2. RW_A is old and updated by soft sync. RW_A is activated and
   executed after reboot. System continues to boot to OS.

Change-Id: Icf97da13e651e7a931b9d507052b9422566eb16c
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/648449

1 files changed, 38 insertions, 26 deletions

diff --git a/common/system.c b/common/system.c
index 62c036baf9..f94c02803e 100644
--- a/common/system.c
+++ b/common/system.c
@@ -412,30 +412,24 @@ test_mockable int system_unsafe_to_overwrite(uint32_t offset, uint32_t size)
 {
 	uint32_t r_offset;
 	uint32_t r_size;
+	enum system_image_copy_t copy = system_get_image_copy();
 
-	switch (system_get_image_copy()) {
+	switch (copy) {
 	case SYSTEM_IMAGE_RO:
-		r_offset = CONFIG_EC_PROTECTED_STORAGE_OFF +
-			   CONFIG_RO_STORAGE_OFF;
 		r_size = CONFIG_RO_SIZE;
 		break;
 	case SYSTEM_IMAGE_RW:
-		r_offset = flash_get_rw_offset(FLASH_RW_SLOT_A);
+	case SYSTEM_IMAGE_RW_B:
 		r_size = CONFIG_RW_SIZE;
 #ifdef CONFIG_RWSIG
 		/* Allow RW sig to be overwritten */
 		r_size -= CONFIG_RW_SIG_SIZE;
 #endif
 		break;
-#ifdef CONFIG_VBOOT_EFS
-	case SYSTEM_IMAGE_RW_B:
-		r_offset = flash_get_rw_offset(FLASH_RW_SLOT_B);
-		r_size = CONFIG_RW_SIZE - CONFIG_RW_SIG_SIZE;
-		break;
-#endif
 	default:
 		return 0;
 	}
+	r_offset = flash_get_rw_offset(copy);
 
 	if ((offset >= r_offset && offset < (r_offset + r_size)) ||
 	    (r_offset >= offset && r_offset < (offset + size)))
@@ -619,17 +613,45 @@ int system_run_image_copy(enum system_image_copy_t copy)
 	return EC_ERROR_UNKNOWN;
 }
 
+enum system_image_copy_t system_get_active_copy(void)
+{
+	uint8_t slot;
+	if (system_get_bbram(SYSTEM_BBRAM_IDX_TRY_SLOT, &slot))
+		slot = SYSTEM_IMAGE_RW_A;
+	/* This makes it return RW_A by default. For example, this happens when
+	 * BBRAM isn't initialized. */
+	return slot == SYSTEM_IMAGE_RW_B ? slot : SYSTEM_IMAGE_RW_A;
+}
+
+enum system_image_copy_t system_get_update_copy(void)
+{
+#ifdef CONFIG_VBOOT_EFS
+	return system_get_active_copy() == SYSTEM_IMAGE_RW_A ?
+			SYSTEM_IMAGE_RW_B : SYSTEM_IMAGE_RW_A;
+#else
+	return SYSTEM_IMAGE_RW_A;
+#endif
+}
+
+int system_set_active_copy(enum system_image_copy_t copy)
+{
+	return system_set_bbram(SYSTEM_BBRAM_IDX_TRY_SLOT, copy);
+}
+
 /*
  * This is defined in system.c instead of flash.c because it's called even
  * on the boards which don't include flash.o. (e.g. hadoken, stm32l476g-eval)
  */
-uint32_t flash_get_rw_offset(enum flash_rw_slot slot)
+uint32_t flash_get_rw_offset(enum system_image_copy_t copy)
 {
 #ifdef CONFIG_VBOOT_EFS
-	if (slot == FLASH_RW_SLOT_B)
+	if (copy == SYSTEM_IMAGE_RW_B)
 		return CONFIG_EC_WRITABLE_STORAGE_OFF + CONFIG_RW_B_STORAGE_OFF;
 #endif
-	return CONFIG_EC_WRITABLE_STORAGE_OFF + CONFIG_RW_STORAGE_OFF;
+	if (is_rw_image(copy))
+		return CONFIG_EC_WRITABLE_STORAGE_OFF + CONFIG_RW_STORAGE_OFF;
+
+	return CONFIG_EC_PROTECTED_STORAGE_OFF + CONFIG_RO_STORAGE_OFF;
 }
 
 static const struct image_data *system_get_image_data(
@@ -657,17 +679,7 @@ static const struct image_data *system_get_image_data(
 	 * Read the version information from the proper location
 	 * on storage.
 	 */
-	switch (copy) {
-	case SYSTEM_IMAGE_RW:
-		addr += flash_get_rw_offset(FLASH_RW_SLOT_A);
-		break;
-	case SYSTEM_IMAGE_RW_B:
-		addr += flash_get_rw_offset(FLASH_RW_SLOT_B);
-		break;
-	default:
-		addr += CONFIG_EC_PROTECTED_STORAGE_OFF + CONFIG_RO_STORAGE_OFF;
-		break;
-	}
+	addr += flash_get_rw_offset(copy);
 
 #ifdef CONFIG_MAPPED_STORAGE
 	addr += CONFIG_MAPPED_STORAGE_BASE;
@@ -1224,12 +1236,12 @@ DECLARE_CONSOLE_COMMAND(sysrq, command_sysrq,
 static int host_command_get_version(struct host_cmd_handler_args *args)
 {
 	struct ec_response_get_version *r = args->response;
-	enum flash_rw_slot active_slot = flash_get_active_slot();
+	enum system_image_copy_t active_slot = system_get_active_copy();
 
 	strzcpy(r->version_string_ro, system_get_version(SYSTEM_IMAGE_RO),
 		sizeof(r->version_string_ro));
 	strzcpy(r->version_string_rw,
-		system_get_version(flash_slot_to_image(active_slot)),
+		system_get_version(active_slot),
 		sizeof(r->version_string_rw));
 
 	switch (system_get_image_copy()) {