[alert_handler/doc] Documentation update
Signed-off-by: Michael Schaffner <msf@google.com>
diff --git a/hw/ip/alert_handler/doc/_index.md b/hw/ip/alert_handler/doc/_index.md
index f8a6dc9..dba5297 100644
--- a/hw/ip/alert_handler/doc/_index.md
+++ b/hw/ip/alert_handler/doc/_index.md
@@ -156,7 +156,8 @@
Signal | Direction | Type | Description
------------------------|------------------|---------------- |---------------
`crashdump_o` | `output` | packed `struct` | This is a collection of alert handler state registers that can be latched by hardware debugging circuitry, if needed.
-`entropy_i` | `input` | `logic` | Entropy input bit for LFSRtimer (can be connected to TRNG, otherwise tie off to `1'b0` if unused).
+`otp_edn_o` | `output` | `otp_edn_req_t` | Entropy request to the entropy distribution network for LFSR reseeding and ephemeral key derivation.
+`otp_edn_i` | `input` | `otp_edn_rsp_t` | Entropy acknowledgment to the entropy distribution network for LFSR reseeding and ephemeral key derivation.
`alert_tx_i[<number>]` | `input` | packed `alert_tx_t` array | Incoming alert or ping response(s), differentially encoded. Index range: `[NAlerts-1:0]`
`alert_rx_o[<number>]` | `output` | packed `alert_rx_t` array | Outgoing alert acknowledgment and ping requests, differentially encoded. Index range: `[NAlerts-1:0]`
`esc_tx_o[<sev>]` | `output` | packed `esc_tx_t` array | Escalation or ping request, differentially encoded. Index corresponds to severity level, and ranges from 0 to 3.
@@ -810,15 +811,19 @@
1. Ping Timer:
- The FSM is sparsely encoded.
- - The LFSR counter is duplicated (**TODO**).
+ - The LFSR and the counter are duplicated.
- If the FSM or counter are glitched into an invalid state, all internal ping fail alerts will be permanently asserted.
2. Escalation Timers:
- The escalation timer FSMs are sparsely encoded.
- - The escalation timer counters are duplicated (**TODO**).
- - The escalation accumulators are duplicated (**TODO**).
+ - The escalation timer counters are duplicated.
+ - The escalation accumulators are duplicated.
- If one of these FSMs, counters or accumulators are glitched into an invalid state, all escalation actions will be triggered and the affected FSM goes into a terminal `FsmError` state.
+3. CSRs (**TODO: this is TBD and not implemented yet**):
+ - Critical configuration CSRs are shadowed.
+ - The shadow CSRs can trigger additional internal alerts for CSR storage and update failures.
+ These internal alerts are fed back into the alert classifier in the same manner as the ping and integrity failure alerts.
# Programmers Guide
