new "stellaris recover" command

Stellaris chips have a procedure for restoring the chip to
what's effectively the "as-manufactured" state, with all the
non-volatile memory erased.  That includes all flash memory,
plus things like the flash protection bits and various control
words which can for example disable debugger access.  clearly,
this can be useful during development.

Luminary/TI provides an MS-Windows utility to perform this
procedure along with its Stellaris developer kits.  Now OpenOCD
users will no longer need to use that MS-Windows utility.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

1 files changed, 66 insertions, 0 deletions

diff --git a/src/flash/nor/stellaris.c b/src/flash/nor/stellaris.c
index 107b1c6d..21a0cffd 100644
--- a/src/flash/nor/stellaris.c
+++ b/src/flash/nor/stellaris.c
@@ -1170,13 +1170,79 @@ COMMAND_HANDLER(stellaris_handle_mass_erase_command)
 	return ERROR_OK;
 }
 
+/**
+ * Perform the Stellaris "Recovering a 'Locked' Device procedure.
+ * This performs a mass erase and then restores all nonvolatile registers
+ * (including USER_* registers and flash lock bits) to their defaults.
+ * Accordingly, flash can be reprogrammed, and JTAG can be used.
+ *
+ * NOTE that DustDevil parts (at least rev A0 silicon) have errata which
+ * can affect this operation if flash protection has been enabled.
+ */
+COMMAND_HANDLER(stellaris_handle_recover_command)
+{
+	struct flash_bank *bank;
+	int retval;
+
+	retval = CALL_COMMAND_HANDLER(flash_command_get_bank, 0, &bank);
+	if (retval != ERROR_OK)
+		return retval;
+
+	/* REVISIT ... it may be worth sanity checking that the AP is
+	 * inactive before we start.  ARM documents that switching a DP's
+	 * mode while it's active can cause fault modes that need a power
+	 * cycle to recover.
+	 */
+
+	/* assert SRST */
+	if (!(jtag_get_reset_config() & RESET_HAS_SRST)) {
+		LOG_ERROR("Can't recover Stellaris flash without SRST");
+		return ERROR_FAIL;
+	}
+	jtag_add_reset(0, 1);
+
+	for (int i = 0; i < 5; i++) {
+		retval = dap_to_swd(bank->target);
+		if (retval != ERROR_OK)
+			goto done;
+
+		retval = dap_to_jtag(bank->target);
+		if (retval != ERROR_OK)
+			goto done;
+	}
+
+	/* de-assert SRST */
+	jtag_add_reset(0, 0);
+	retval = jtag_execute_queue();
+
+	/* wait 400+ msec ... OK, "1+ second" is simpler */
+	sleep(1);
+
+	/* USER INTERVENTION required for the power cycle
+	 * Restarting OpenOCD is likely needed because of mode switching.
+	 */
+	LOG_INFO("USER ACTION:  "
+		"power cycle Stellaris chip, then restart OpenOCD.");
+
+done:
+	return retval;
+}
+
 static const struct command_registration stellaris_exec_command_handlers[] = {
 	{
 		.name = "mass_erase",
 		.handler = stellaris_handle_mass_erase_command,
 		.mode = COMMAND_EXEC,
+		.usage = "bank_id",
 		.help = "erase entire device",
 	},
+	{
+		.name = "recover",
+		.handler = stellaris_handle_recover_command,
+		.mode = COMMAND_EXEC,
+		.usage = "bank_id",
+		.help = "recover locked device",
+	},
 	COMMAND_REGISTRATION_DONE
 };
 static const struct command_registration stellaris_command_handlers[] = {