km_kpv_eraser

Erase one KPV key slot with pseudo-random data when its CTRL erase bit is asserted.

An FSM walks the WORDS_PER_SLOT (16 by default) words of the selected slot, emitting a logical {slot, word} address and a pseudo-random data word sourced from a maximal-length LFSR (prim_lfsr, GAL_XOR). The parent (km_kpv) routes these through the shared KPV scrambler, when enabled, and into the key register file, so the slot is overwritten with random data. A one-cycle erase_done pulse accompanies the last word write; km_kpv then clears the self-clearing erase bit and either frees an unsealed slot by clearing its lock bits or retires a sealed slot by setting lock_use.

Multiple pending erase requests are serviced sequentially, lowest slot index first. Erase is intentionally not gated by the slot lock_write/lock_use bits.

The LFSR is seeded to all-ones on cold reset only (no warm reset); the exact seed value is not security-relevant.

Parameters

Table 1. Parameters
Name	Type	Default	Description
`NUM_SLOTS`	`int unsigned`	`64`	Number of key slots.
`WORDS_PER_SLOT`	`int unsigned`	`16`	Key-data words in each slot; one erase writes word indices 0 to WORDS_PER_SLOT - 1.
`DATA_WIDTH`	`int unsigned`	`32`	Key-data word width; also sizes the LFSR.

Ports

Table 2. Ports
Name	Direction	Type	Description
`clk_i`	input	`logic`	System clock.
`cold_rst_ni`	input	`logic`	Cold reset (AASD); seeds LFSR all-ones and returns the FSM to idle.
`erase_req_i`	input	`logic [NUM_SLOTS-1:0]`	Per-slot erase requests (CTRL[i].erase.value).
`wr_en_o`	output	`logic`	Register-file write stream enable (logical address; parent applies the scrambler).
`wr_slot_o`	output	`logic [$clog2(NUM_SLOTS)-1:0]`	Write stream: logical slot index being erased.
`wr_word_o`	output	`logic [$clog2(WORDS_PER_SLOT)-1:0]`	Write stream: word index within the slot.
`wr_data_o`	output	`logic [DATA_WIDTH-1:0]`	Write stream: pseudo-random data from the LFSR.
`erase_done_o`	output	`logic [NUM_SLOTS-1:0]`	One-cycle pulse per slot when its erase completes (last word written).
`busy_o`	output	`logic`	High while an erase is in progress; the parent gives this priority on the shared scrambler / regfile write port.