| --- |
| title: "NMI Generator Technical Specification" |
| --- |
| |
| # Overview |
| |
| This document specifies the functionality of the non-maskable interrupt generator (`nmi_gen`) peripheral. |
| This module conforms to the [OpenTitan guideline for peripheral device functionality.]({{< relref "doc/rm/comportability_specification" >}}). |
| See that document for integration overview within the broader OpenTitan top level system. |
| The module provides a mechanism to test the alert handler escalation signals (see [alert handler spec]({{< ref "hw/ip/alert_handler/doc" >}})), and will be modified or even replaced in the near future. |
| |
| |
| ## Features |
| |
| - Contains four escalation receivers to receive escalation signals from the alert handler |
| - Produces four regular interrupts that are derived from the alert handler escalation signals |
| |
| ## Description |
| |
| The NMI generator module is a simple wrapper module that instantiates four escalation receivers (which are described in more detail in the alert handler spec). |
| The output of these receivers are converted into regular interrupt requests that can be connected to the PLIC/processor core in order to test the escalation mechanism. |
| |
|  |
| |
| ## Parameters |
| |
| The following table lists the main parameters used throughout the `nmi_gen` design. |
| |
| Localparam | Default (Max) | Description |
| ---------------|-----------------------|--------------- |
| N_ESC_SEV | 4 (-) | Number of escalation receivers (should be left as is). |
| |
| ## Signals |
| |
| {{< hwcfg "hw/ip/nmi_gen/data/nmi_gen.hjson" >}} |
| |
| The table below lists other `nmi_gen` signals. |
| |
| Signal | Direction | Type | Description |
| -------------------------------------|------------------|-------------------------|--------------- |
| `esc_tx_i[N_ESC_SEV-1:0]` | `input` | packed `esc_tx_t` array | Differentially encoded escalation signals coming from the alert handler. |
| `esc_rx_o[N_ESC_SEV-1:0]` | `output` | packed `esc_rx_t` array | Differentially encoded response signals to alert handler. |
| |
| |
| ## Register Table |
| |
| {{< registers "hw/ip/nmi_gen/data/nmi_gen.hjson" >}} |
