[OpenOCD-devel] [PATCH]: 256fd3e jtag/drivers/cmsis-dap: hack to attach a secured SAMD/R/L/C

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Tomas Vanek (va...@fb...) just uploaded a new patch set to Gerrit, which you can find at http://openocd.zylin.com/4044

-- gerrit

commit 256fd3ec90db8da422c728b65204f8e21f34a879
Author: Tomas Vanek <va...@fb...>
Date:   Fri Mar 3 21:58:39 2017 +0100

    jtag/drivers/cmsis-dap: hack to attach a secured SAMD/R/L/C
    
    Without the change a secured SAMD/R/L/C device cannot be attached
    and therefore neither erased.
    
    Hack in CMSIS-DAP optionally issues a cold-plug reset sequence at OpenOCD
    init. It enables limited access to DSU of the device and makes chip
    erase possible.
    
    Change-Id: I9aa78b7bcc23909732d1d4555178139533130a14
    Signed-off-by: Tomas Vanek <va...@fb...>
    Reported-by: Thomas Irmen <ti...@gm...>

diff --git a/doc/openocd.texi b/doc/openocd.texi
index 45b341c..ea74cba 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -2390,6 +2390,11 @@ Specifies the @var{serial} of the CMSIS-DAP device to use.
 If not specified, serial numbers are not considered.
 @end deffn
 
+@deffn {Config Command} {cmsis_dap_init_samd_cold_plug}
+Issues cold-plug reset sequence during OpenOCD init.
+Use for attaching to a secured Atmel SAMD/R/L/C device.
+@end deffn
+
 @deffn {Command} {cmsis-dap info}
 Display various device information, like hardware version, firmware version, current bus status.
 @end deffn
@@ -4999,13 +5004,18 @@ processor to be halted.
 @deffn Command {at91samd set-security}
 Secures the Flash via the Set Security Bit (SSB) command. This prevents access
 to the Flash and can only be undone by using the chip-erase command which
-erases the Flash contents and turns off the security bit. Warning: at this
-time, openocd will not be able to communicate with a secured chip and it is
-therefore not possible to chip-erase it without using another tool.
+erases the Flash contents and turns off the security bit.
 
 @example
 at91samd set-security enable
 @end example
+
+To erase a secured device using a CMSIS-DAP adapter run:
+@example
+openocd -f interface/cmsis-dap.cfg -c "transport select swd" -f at91samdXX.cfg \
+  -c cmsis_dap_init_samd_cold_plug -c "reset_config srst_only" -c init \
+  -c "at91samd chip-erase" -c shutdown
+@end example
 @end deffn
 
 @deffn Command {at91samd eeprom}
diff --git a/src/jtag/drivers/cmsis_dap_usb.c b/src/jtag/drivers/cmsis_dap_usb.c
index dd37522..c59549e 100644
--- a/src/jtag/drivers/cmsis_dap_usb.c
+++ b/src/jtag/drivers/cmsis_dap_usb.c
@@ -208,6 +208,9 @@ static int queued_retval;
 
 static struct cmsis_dap *cmsis_dap_handle;
 
+static bool samd_cold_plug;
+
+
 static int cmsis_dap_usb_open(void)
 {
 	hid_device *dev = NULL;
@@ -974,6 +977,18 @@ static int cmsis_dap_init(void)
 		}
 	}
 
+	if (samd_cold_plug) {
+		retval = cmsis_dap_cmd_DAP_SWJ_Pins(0, SWJ_PIN_SRST | SWJ_PIN_TCK, 100, NULL);
+		if (retval != ERROR_OK)
+			return ERROR_FAIL;
+
+		retval = cmsis_dap_cmd_DAP_SWJ_Pins(SWJ_PIN_SRST, SWJ_PIN_SRST | SWJ_PIN_TCK, 100, NULL);
+		if (retval != ERROR_OK)
+			return ERROR_FAIL;
+
+		LOG_INFO("SAMD reset cold-plug sequence issued, device is held in reset.");
+	}
+
 	cmsis_dap_cmd_DAP_LED(0x00);			/* Both LEDs off */
 
 	LOG_INFO("CMSIS-DAP: Interface ready");
@@ -1586,6 +1601,13 @@ COMMAND_HANDLER(cmsis_dap_handle_serial_command)
 	return ERROR_OK;
 }
 
+
+COMMAND_HANDLER(cmsis_dap_handle_samd_cold_plug_command)
+{
+	samd_cold_plug = true;
+	return ERROR_OK;
+}
+
 static const struct command_registration cmsis_dap_subcommand_handlers[] = {
 	{
 		.name = "info",
@@ -1619,6 +1641,13 @@ static const struct command_registration cmsis_dap_command_handlers[] = {
 		.help = "set the serial number of the adapter",
 		.usage = "serial_string",
 	},
+	{
+		.name = "cmsis_dap_init_samd_cold_plug",
+		.handler = &cmsis_dap_handle_samd_cold_plug_command,
+		.mode = COMMAND_CONFIG,
+		.help = "issue SAMD/R/L/C cold-plug sequence during init to attach a secured device",
+		.usage = "",
+	},
 	COMMAND_REGISTRATION_DONE
 };
 

--