AM623: get otp row lock status

li weiyu

Expert 1150 points

Part Number: AM623

Tool/software:

Hi, TI expert!

I have a development environment for am6234, with our own evaluation board.

The software SDK version is PROCESSOR-SDK-LINUX-RT-AM62X-08.06.00.42.

After execution, there is a log as shown in the following figure：

From the test results, it can be seen that a request to obtain the OTP row lock status was sent, but there was no response.

May I ask what caused this problem and how to solve it?

Or does TI have an official interface function to obtain the lock status of otp row？

Regards,

over 1 year ago

0 Prashant Shivhare over 1 year ago

TI__Guru* 86011 points

Hello,

This is a known issue as the DM did not support TISCI Secure messages prior to MCU+ SDK v09_02_00_38. The support then was added with the following patches

So, the option is to either migrate to the latest SDK version (highly recommended) or backport these patches to the particular MCU+ SDK version you are using.

Attached is the backported patch, just for TISCI_MSG_GET_OTP_ROW_LOCK_STATUS, for MCU+ SDK v08_06_00_18.

diff --git a/source/drivers/device_manager/sciclient_direct/sciclient.c b/source/drivers/device_manager/sciclient_direct/sciclient.c
index 02782d3..0ab94b9 100755
--- a/source/drivers/device_manager/sciclient_direct/sciclient.c
+++ b/source/drivers/device_manager/sciclient_direct/sciclient.c
@@ -1296,6 +1296,7 @@ uint32_t Sciclient_getCurrentContext(uint16_t messageType)
        (TISCI_MSG_SA2UL_GET_DKEK == messageType) ||
        (TISCI_MSG_ENTER_SLEEP == messageType) ||
        (TISCI_MSG_KEY_WRITER == messageType) ||
+       (TISCI_MSG_GET_OTP_ROW_LOCK_STATUS == messageType) ||
        (TISCI_MSG_WRITE_OTP_ROW == messageType) ||
        (TISCI_MSG_READ_OTP_MMR == messageType))
     {
diff --git a/source/drivers/device_manager/sciclient_direct/sciclient_direct.c b/source/drivers/device_manager/sciclient_direct/sciclient_direct.c
index 3ee74e0..1356bca 100644
--- a/source/drivers/device_manager/sciclient_direct/sciclient_direct.c
+++ b/source/drivers/device_manager/sciclient_direct/sciclient_direct.c
@@ -414,6 +414,7 @@ int32_t Sciclient_service (const Sciclient_ReqPrm_t *pReqPrm,
             case TISCI_MSG_KEY_WRITER:
             case TISCI_MSG_WRITE_OTP_ROW:
             case TISCI_MSG_READ_OTP_MMR:
+            case TISCI_MSG_GET_OTP_ROW_LOCK_STATUS:
                 ret = Sciclient_serviceSecureProxy(pReqPrm, pRespPrm);
                 break;
             /* RM messages processed by Secure RM within TIFS on M3 */

Regards,

Prashant

0 li weiyu over 1 year ago in reply to Prashant Shivhare

Expert 1150 points

Hello,

Why did the above error occur? Can't otp efuse be written multiple times without locking the otp row？

Regards,

Prashant

0 Prashant Shivhare over 1 year ago in reply to li weiyu

TI__Guru* 86011 points

li weiyu said:
Can't otp efuse be written multiple times without locking the otp row？

They can be but under the condition that the reprogramming does not result in a bit flip of 1 -> 0. This limitation exists from the hardware itself as any OTP bit once flipped from 0 (initial state) to 1 cannot be flipped again.

0 li weiyu over 1 year ago in reply to Prashant Shivhare

Expert 1150 points

Hello,

I call the following API interface to write the row of otp efuse：
https://software-dl.ti.com/tisci/esd/latest/2_tisci_msgs/security/extended_otp.html#write-otp-row

So I don't need to call the following interface to lock the row of otp efuse anymore？
https://software-dl.ti.com/tisci/esd/latest/2_tisci_msgs/security/extended_otp.html#tisci-msg-lock-otp-row-lock-otp-row

If that's the case, what is the purpose of this API interface?

Regards,

+1 Prashant Shivhare over 1 year ago in reply to li weiyu

TI__Guru* 86011 points

1) TISCI_MSG_WRITE_OTP_ROW

Programs the given row in the Extended OTP.
The bits once flipped to 1 from their initial state (0) cannot be flipped again.
The bits which are still in their initial state can be still programmed to 1.

2) TISCI_MSG_LOCK_OTP_ROW

Enables the R/W lock for a given row in the Extended OTP.
Once the write lock is enabled for a row, any bit in that row cannot be further programmed. This means the bits which are still in their initial state (0) cannot be programmed to 1.

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AM623: get otp row lock status