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Update polling method for IDevID CSR in Caliptra.md #585

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Update polling method for IDevID CSR in Caliptra.md #585

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Update polling method for IDevID CSR in Caliptra.md
Nitsirks Nov 26, 2025
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Update polling method for IDevID CSR readiness
Nitsirks Nov 26, 2025
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2 changes: 1 addition & 1 deletion doc/Caliptra.md
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Expand Up @@ -428,7 +428,7 @@ Combine the internal TRNG output with a Manufacturing time provided value to pro
6. HVM, through JTAG or using the Caliptra SoC interface, sets “CPTRA\_DBG\_MANUF\_SERVICE\_REG” bit 0 to request a CSR.
7. HVM, through JTAG or using the Caliptra SoC interface, writes to “CPTRA\_BOOTFSM\_GO” to allow Caliptra’s internal BootFSM to continue to bring up microcontroller out of reset.
8. ROM reads the manufacturing state encoding from the “CPTRA\_DBG\_MANUF\_SERVICE\_REG” register, acquires the mailbox lock, and populates the Caliptra internal SRAM (the mailbox SRAM hardware structure is reused) with the CSR.
9. HVM, through JTAG or using the SoC interface, polls for the “IDevID CSR ready" bit 24 that is set in “CPTRA\_FLOW\_STATUS” register.
9. HVM, using the SoC interface, polls for the “IDevID CSR ready" bit 24 that is set in “CPTRA\_FLOW\_STATUS” register.

@calebofearth calebofearth Nov 26, 2025

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This should also be fixed in the 2.0 and 1.X versions.

@Nitsirks Nitsirks Nov 26, 2025

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1.x version has been updated.
2.0 doc points to an html version of the spec in main

@calebofearth calebofearth Dec 1, 2025

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That 2.0 HTML doc is rendered from the .ocp source, which I think needs to be updated too:
https://github.com/chipsalliance/Caliptra/blob/main/doc/caliptra_20/Caliptra.ocp

10. HVM reads mbox\_status\[3:0\] to check if the data is ready to be read (DATA\_READY encoding).
11. HVM must clear bit 0 of CPTRA\_DBG\_MANUF\_SERVICE\_REG, indicating that it completed reading the CSR.
12. Caliptra ROM opens the Caliptra Mailbox for SoC usages, such as FW loading (if required in some HVM flows). The SoC is only allowed to request a lock of the AXI-exposed mailbox interface after this CSR operation is complete.
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