common/update_fw: Board/chip-specific first_response_pdu

cr50 and hammer/common code are such different chips that reusing the
same first_response_pdu does not make much sense.

Instead, we can use 2 different headers, the updater knows which
response to expect based on USB product ID.

In the common code answer, we can reply with the EC version string,
as well as rollback information and key version ID, which will
be required for reliable updating.

BRANCH=none
BUG=b:35587171
BUG=b:36375666
TEST=usb_updater2 can update hammer, and read its version, rollback
     version and key version.

Change-Id: I20b04070606767c71df3e6286d53e238e13375c0
Reviewed-on: https://chromium-review.googlesource.com/476452
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Nick Sanders <nsanders@chromium.org>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>

1 files changed, 35 insertions, 22 deletions

diff --git a/common/update_fw.c b/common/update_fw.c
index 8135370b7c..7a51e6977f 100644
--- a/common/update_fw.c
+++ b/common/update_fw.c
@@ -9,10 +9,13 @@
 #include "flash.h"
 #include "hooks.h"
 #include "include/compile_time_macros.h"
+#include "rollback.h"
+#include "rwsig.h"
 #include "system.h"
 #include "uart.h"
 #include "update_fw.h"
 #include "util.h"
+#include "vb21_struct.h"
 
 #define CPRINTF(format, args...) cprintf(CC_USB, format, ## args)
 
@@ -98,17 +101,26 @@ static int contents_allowed(uint32_t block_offset,
  */
 void fw_update_start(struct first_response_pdu *rpdu)
 {
+	const char *version;
+#ifdef CONFIG_RWSIG_TYPE_RWSIG
+	const struct vb21_packed_key *vb21_key;
+#endif
+
+	rpdu->header_type = htobe16(UPDATE_HEADER_TYPE_COMMON);
+
 	/* Determine the valid update section. */
 	switch (system_get_image_copy()) {
 	case SYSTEM_IMAGE_RO:
 		/* RO running, so update RW */
 		update_section.base_offset = CONFIG_RW_MEM_OFF;
 		update_section.top_offset = CONFIG_RW_MEM_OFF + CONFIG_RW_SIZE;
+		version = system_get_version(SYSTEM_IMAGE_RW);
 		break;
 	case SYSTEM_IMAGE_RW:
 		/* RW running, so update RO */
 		update_section.base_offset = CONFIG_RO_MEM_OFF;
 		update_section.top_offset = CONFIG_RO_MEM_OFF + CONFIG_RO_SIZE;
+		version = system_get_version(SYSTEM_IMAGE_RO);
 		break;
 	default:
 		CPRINTF("%s:%d\n", __func__, __LINE__);
@@ -116,27 +128,23 @@ void fw_update_start(struct first_response_pdu *rpdu)
 		return;
 	}
 
-	/*
-	 * TODO(b/36375666): We reuse the same structure as cr50 updater, but
-	 * there isn't a whole lot that can be shared... We should probably
-	 * switch to a board-specific response packet (at least common vs
-	 * cr50-specific).
-	 */
-	rpdu->backup_ro_offset = htobe32(update_section.base_offset);
-	rpdu->backup_rw_offset = 0x0;
-
-	/* RO header information. */
-	rpdu->shv[0].minor = 0;
-	rpdu->shv[0].major = 0;
-	rpdu->shv[0].epoch = 0;
-	rpdu->keyid[0] = 0;
-
-	/* RW header information. */
-	rpdu->shv[1].minor = 0;
-	rpdu->shv[1].major = 0;
-	rpdu->shv[1].epoch = 0;
-
-	rpdu->keyid[1] = 0;
+	rpdu->common.maximum_pdu_size = htobe32(CONFIG_UPDATE_PDU_SIZE);
+	rpdu->common.flash_protection = htobe32(flash_get_protect());
+	rpdu->common.offset = htobe32(update_section.base_offset);
+	if (version)
+		memcpy(rpdu->common.version, version,
+			sizeof(rpdu->common.version));
+
+#ifdef CONFIG_ROLLBACK
+	rpdu->common.min_rollback = htobe32(rollback_get_minimum_version());
+#else
+	rpdu->common.min_rollback = htobe32(-1);
+#endif
+
+#ifdef CONFIG_RWSIG_TYPE_RWSIG
+	vb21_key = (const struct vb21_packed_key *)CONFIG_RO_PUBKEY_ADDR;
+	rpdu->common.key_version = htobe32(vb21_key->key_version);
+#endif
 }
 
 void fw_update_command_handler(void *body,
@@ -169,8 +177,13 @@ void fw_update_command_handler(void *body,
 
 		/* First, prepare the response structure. */
 		memset(rpdu, 0, sizeof(*rpdu));
+		/*
+		 * TODO(b/36375666): The response size can be shorter depending
+		 * on which board-specific type of response we provide. This
+		 * may send trailing 0 bytes, which should be harmless.
+		 */
 		*response_size = sizeof(*rpdu);
-		rpdu->protocol_version = htobe32(UPDATE_PROTOCOL_VERSION);
+		rpdu->protocol_version = htobe16(UPDATE_PROTOCOL_VERSION);
 
 		/* Setup internal state (e.g. valid sections, and fill rpdu) */
 		fw_update_start(rpdu);