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80 lines
2.9 KiB
Python
80 lines
2.9 KiB
Python
# -*- coding: utf-8 -*-
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#=======================================================================
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#
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# Copyright (C) 2023 Tillitis AB
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# Written by Myrtle Shah <gatecat@ds0.me>
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# SPDX-License-Identifier: GPL-2.0-only
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#
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# patch_uds_udi.py
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# --------------
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# Python program that patches the UDS and UDI implemented using
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# named LUT4 instances to have unique initial values, not the generic
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# values used during synthesis, p&r and mapping. This allows us to
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# generate device unique bitstreams without running the complete flow.
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#
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# Both the UDI and UDS are using bit indexing from 32 LUTs for each
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# word, i.e., the first word consists of bit 0 from each 32 LUTs and
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# so on.
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#
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# The size requirements for the UDI and UDS are specified as 1 bit (8
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# bytes of data) and 3 bits (32 bytes of data), respectively. The UDI
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# does not occupy the entire LUT4 instance, and to conserve resources,
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# the pattern of the UDI is repeated over the unused portion of the
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# LUT4 instance. This eliminates the need to drive the three MSB pins
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# while still achieving the correct output.
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#
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# In the case of UDS, a read-enable signal is present, and the most
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# significant bit serves as the read-enable input. This requires the
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# lower half of initialization bits to be forced to zero, ensuring
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# that the memory outputs zero when the read-enable signal is
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# inactive.
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#
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#
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#=======================================================================
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import os
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def parse_hex(file, length):
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data = []
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with open(file, "r") as f:
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for line in f:
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l = line.strip()
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if len(l) > 0:
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data.append(int(l, 16))
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assert len(data) == length, len(data)
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return data
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def rewrite_lut(lut, idx, data, has_re=False):
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# each LUT provides one bit per 32-bit word out of 64/256 bits total
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new_init = 0
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for i, word in enumerate(data):
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if (word >> idx) & 0x1:
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# repeat so inputs above address have a don't care value
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repeat = (16 // len(data))
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for k in range(repeat):
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# UDS also has a read enable
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# LUT output is zero if this isn't asserted
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if has_re and k < (repeat // 2):
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continue
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new_init |= (1 << (k * len(data) + i))
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lut.setParam("LUT_INIT", f"{new_init:016b}")
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uds = parse_hex(os.environ["UDS_HEX"], 8)
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udi = parse_hex(os.environ["UDI_HEX"], 2)
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uds_lut_count = 0
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udi_lut_count = 0
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for cell_name, cell in ctx.cells:
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if "uds_rom_idx" in cell.attrs:
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index = int(cell.attrs["uds_rom_idx"], 2)
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rewrite_lut(cell, index, uds, True)
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uds_lut_count += 1
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if "udi_rom_idx" in cell.attrs:
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index = int(cell.attrs["udi_rom_idx"], 2)
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rewrite_lut(cell, index, udi, False)
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udi_lut_count += 1
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assert uds_lut_count == 32, uds_lut_count
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assert udi_lut_count == 32, udi_lut_count
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write_bitstream(ctx, os.environ["OUT_ASC"])
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