update_fw: Add support for touchpad update over virtual address

In the field, we want to update touchpad FW using the same USB
update protocol as the main EC FW.

To distinguish between EC FW update and touchpad FW update, we
use a virtual address, defined by CONFIG_TOUCHPAD_VIRTUAL_OFF,
that does not map to anything on the EC chip.

Also, this will allow us to verify hashes of each block of the
flashed touchpad firmware, so that we can ensure its integrity
before flashing it into the touchpad. A stub is implemented in
update_fw.c:contents_allowed.

BRANCH=none
BUG=b:63993173
TEST=With follow-up CLs, ./usb_updater2 -p 144.0_2.0.bin

Change-Id: I4de1d7d138fc01fe1552a4173c8ef208ecb834a7
Signed-off-by: Nicolas Boichat <drinkcat@google.com>
Reviewed-on: https://chromium-review.googlesource.com/593373
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Chun-ta Lin <itspeter@chromium.org>

1 files changed, 54 insertions, 0 deletions

diff --git a/common/update_fw.c b/common/update_fw.c
index c08e8322b5..93206f4066 100644
--- a/common/update_fw.c
+++ b/common/update_fw.c
@@ -11,6 +11,7 @@
 #include "include/compile_time_macros.h"
 #include "rollback.h"
 #include "rwsig.h"
+#include "sha256.h"
 #include "system.h"
 #include "uart.h"
 #include "update_fw.h"
@@ -25,6 +26,20 @@ struct {
 	uint32_t top_offset;
 } update_section;
 
+#ifdef CONFIG_TOUCHPAD_VIRTUAL_OFF
+/*
+ * Check if a block is within touchpad FW virtual address region, and
+ * is therefore meant to be flashed to the touchpad.
+ */
+static int is_touchpad_block(uint32_t block_offset, size_t body_size)
+{
+	return (block_offset >= CONFIG_TOUCHPAD_VIRTUAL_OFF) &&
+	       (block_offset + body_size) <=
+			(CONFIG_TOUCHPAD_VIRTUAL_OFF +
+				CONFIG_TOUCHPAD_VIRTUAL_SIZE);
+}
+#endif
+
 /*
  * Verify that the passed in block fits into the valid area. If it does, and
  * is destined to the base address of the area - erase the area contents.
@@ -62,6 +77,11 @@ static uint8_t check_update_chunk(uint32_t block_offset, size_t body_size)
 		return UPDATE_SUCCESS;
 	}
 
+#ifdef CONFIG_TOUCHPAD_VIRTUAL_OFF
+	if (is_touchpad_block(block_offset, body_size))
+		return UPDATE_SUCCESS;
+#endif
+
 	CPRINTF("%s:%d %x, %d section base %x top %x\n",
 		__func__, __LINE__,
 		block_offset, body_size,
@@ -90,6 +110,22 @@ static void new_chunk_written(uint32_t block_offset)
 static int contents_allowed(uint32_t block_offset,
 			    size_t body_size, void *update_data)
 {
+#ifdef CONFIG_TOUCHPAD_VIRTUAL_OFF
+	if (is_touchpad_block(block_offset, body_size)) {
+		struct sha256_ctx ctx;
+		uint8_t *tmp;
+
+		SHA256_init(&ctx);
+		SHA256_update(&ctx, update_data, body_size);
+		tmp = SHA256_final(&ctx);
+		/* TODO(b:63993173): Actually validate the SHA. */
+		CPRINTF("%s: SHA %08x %02x..%02x\n", __func__,
+			block_offset - CONFIG_TOUCHPAD_VIRTUAL_OFF,
+			tmp[0], tmp[31]);
+
+		return 1;
+	}
+#endif
 	return 1;
 }
 
@@ -226,6 +262,24 @@ void fw_update_command_handler(void *body,
 	 * here, which should probably be merged into contents_allowed...
 	 */
 
+#ifdef CONFIG_TOUCHPAD_VIRTUAL_OFF
+	if (is_touchpad_block(block_offset, body_size)) {
+		if (touchpad_update_write(
+				block_offset - CONFIG_TOUCHPAD_VIRTUAL_OFF,
+				body_size, update_data)	!= EC_SUCCESS) {
+			*error_code = UPDATE_WRITE_FAILURE;
+			CPRINTF("%s:%d update write error\n",
+				__func__, __LINE__);
+			return;
+		}
+
+		new_chunk_written(block_offset);
+
+		*error_code = UPDATE_SUCCESS;
+		return;
+	}
+#endif
+
 	CPRINTF("update: 0x%x\n", block_offset + CONFIG_PROGRAM_MEMORY_BASE);
 	if (flash_physical_write(block_offset, body_size, update_data)
 	    != EC_SUCCESS) {