273 lines
5.9 KiB
Ucode
273 lines
5.9 KiB
Ucode
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/*
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* TX ucode for the Intel IXP2400 in POS-PHY mode.
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* Copyright (C) 2004, 2005 Lennert Buytenhek
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* Dedicated to Marija Kulikova.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* Assumptions made in this code:
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* - The IXP2400 MSF is configured for POS-PHY mode, in a mode where
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* only one TBUF partition is used. This includes, for example,
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* 1x32 SPHY and 1x32 MPHY32, but not 4x8 SPHY or 1x32 MPHY4. (This
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* is not an exhaustive list.)
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* - The TBUF uses 64-byte mpackets.
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* - TX descriptors reside in SRAM, and have the following format:
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* struct tx_desc
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* {
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* // to uengine
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* u32 buf_phys_addr;
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* u32 pkt_length;
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* u32 channel;
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* };
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* - Packet data resides in DRAM.
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* - Packet buffer addresses are 8-byte aligned.
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* - Scratch ring 2 is tx_pending.
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* - Scratch ring 3 is tx_done, and has status condition 'full'.
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* - This code is run on all eight threads of the microengine it runs on.
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*/
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#define TX_SEQUENCE_0 0x0060
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#define TBUF_CTRL 0x1800
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#define PARTITION_SIZE 128
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#define PARTITION_THRESH 96
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.sig volatile sig1
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.sig volatile sig2
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.sig volatile sig3
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.reg @old_tx_seq_0
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.reg @mpkts_in_flight
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.reg @next_tbuf_mpacket
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.reg @buffer_handle
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.reg @buffer_start
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.reg @packet_length
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.reg @channel
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.reg @packet_offset
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.reg zero
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immed[zero, 0]
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/*
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* Skip context 0 initialisation?
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*/
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.begin
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br!=ctx[0, mpacket_tx_loop#]
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.end
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/*
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* Wait until all pending TBUF elements have been transmitted.
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*/
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.begin
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.reg read $tx
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.sig zzz
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loop_empty#:
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msf[read, $tx, zero, TX_SEQUENCE_0, 1], ctx_swap[zzz]
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alu_shf[--, --, b, $tx, >>31]
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beq[loop_empty#]
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alu[@old_tx_seq_0, --, b, $tx]
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.end
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immed[@mpkts_in_flight, 0]
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alu[@next_tbuf_mpacket, @old_tx_seq_0, and, (PARTITION_SIZE - 1)]
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immed[@buffer_handle, 0]
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/*
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* Initialise signal pipeline.
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*/
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.begin
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local_csr_wr[SAME_ME_SIGNAL, (&sig1 << 3)]
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.set_sig sig1
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local_csr_wr[SAME_ME_SIGNAL, (&sig2 << 3)]
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.set_sig sig2
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local_csr_wr[SAME_ME_SIGNAL, (&sig3 << 3)]
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.set_sig sig3
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.end
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mpacket_tx_loop#:
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.begin
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.reg tbuf_element_index
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.reg buffer_handle
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.reg sop_eop
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.reg packet_data
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.reg channel
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.reg mpacket_size
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/*
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* If there is no packet currently being transmitted,
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* dequeue the next TX descriptor, and fetch the buffer
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* address, packet length and destination channel number.
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*/
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.begin
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.reg read $stemp $stemp2 $stemp3
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.xfer_order $stemp $stemp2 $stemp3
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.sig zzz
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ctx_arb[sig1]
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alu[--, --, b, @buffer_handle]
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bne[already_got_packet#]
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tx_nobufs#:
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scratch[get, $stemp, zero, 8, 1], ctx_swap[zzz]
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alu[@buffer_handle, --, b, $stemp]
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beq[tx_nobufs#]
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sram[read, $stemp, $stemp, 0, 3], ctx_swap[zzz]
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alu[@buffer_start, --, b, $stemp]
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alu[@packet_length, --, b, $stemp2]
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beq[zero_byte_packet#]
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alu[@channel, --, b, $stemp3]
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immed[@packet_offset, 0]
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already_got_packet#:
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local_csr_wr[SAME_ME_SIGNAL, (0x80 | (&sig1 << 3))]
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.end
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/*
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* Determine tbuf element index, SOP/EOP flags, mpacket
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* offset and mpacket size and cache buffer_handle and
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* channel number.
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*/
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.begin
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alu[tbuf_element_index, --, b, @next_tbuf_mpacket]
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alu[@next_tbuf_mpacket, @next_tbuf_mpacket, +, 1]
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alu[@next_tbuf_mpacket, @next_tbuf_mpacket, and,
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(PARTITION_SIZE - 1)]
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alu[buffer_handle, --, b, @buffer_handle]
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immed[@buffer_handle, 0]
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immed[sop_eop, 1]
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alu[packet_data, --, b, @packet_offset]
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bne[no_sop#]
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alu[sop_eop, sop_eop, or, 2]
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no_sop#:
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alu[packet_data, packet_data, +, @buffer_start]
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alu[channel, --, b, @channel]
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alu[mpacket_size, @packet_length, -, @packet_offset]
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alu[--, 64, -, mpacket_size]
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bhs[eop#]
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alu[@buffer_handle, --, b, buffer_handle]
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immed[mpacket_size, 64]
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alu[sop_eop, sop_eop, and, 2]
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eop#:
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alu[@packet_offset, @packet_offset, +, mpacket_size]
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.end
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/*
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* Wait until there's enough space in the TBUF.
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*/
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.begin
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.reg read $tx
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.reg temp
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.sig zzz
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ctx_arb[sig2]
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br[test_space#]
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loop_space#:
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msf[read, $tx, zero, TX_SEQUENCE_0, 1], ctx_swap[zzz]
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alu[temp, $tx, -, @old_tx_seq_0]
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alu[temp, temp, and, 0xff]
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alu[@mpkts_in_flight, @mpkts_in_flight, -, temp]
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alu[@old_tx_seq_0, --, b, $tx]
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test_space#:
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alu[--, PARTITION_THRESH, -, @mpkts_in_flight]
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blo[loop_space#]
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alu[@mpkts_in_flight, @mpkts_in_flight, +, 1]
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local_csr_wr[SAME_ME_SIGNAL, (0x80 | (&sig2 << 3))]
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.end
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/*
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* Copy the packet data to the TBUF.
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*/
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.begin
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.reg temp
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.sig copy_sig
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alu[temp, mpacket_size, -, 1]
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alu_shf[temp, 0x10, or, temp, >>3]
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alu_shf[temp, 0x10, or, temp, <<21]
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alu_shf[temp, temp, or, tbuf_element_index, <<11]
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alu_shf[--, temp, or, 1, <<18]
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dram[tbuf_wr, --, packet_data, 0, max_8],
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indirect_ref, sig_done[copy_sig]
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ctx_arb[copy_sig]
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.end
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/*
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* Mark TBUF element as ready-to-be-transmitted.
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*/
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.begin
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.reg write $tsw $tsw2
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.xfer_order $tsw $tsw2
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.reg temp
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.sig zzz
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alu_shf[temp, channel, or, mpacket_size, <<24]
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alu_shf[$tsw, temp, or, sop_eop, <<8]
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immed[$tsw2, 0]
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immed[temp, TBUF_CTRL]
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alu_shf[temp, temp, or, tbuf_element_index, <<3]
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msf[write, $tsw, temp, 0, 2], ctx_swap[zzz]
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.end
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/*
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* Resynchronise.
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*/
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.begin
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ctx_arb[sig3]
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local_csr_wr[SAME_ME_SIGNAL, (0x80 | (&sig3 << 3))]
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.end
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/*
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* If this was an EOP mpacket, recycle the TX buffer
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* and signal the host.
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*/
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.begin
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.reg write $stemp
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.sig zzz
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alu[--, sop_eop, and, 1]
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beq[mpacket_tx_loop#]
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tx_done_ring_full#:
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br_inp_state[SCR_Ring3_Status, tx_done_ring_full#]
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alu[$stemp, --, b, buffer_handle]
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scratch[put, $stemp, zero, 12, 1], ctx_swap[zzz]
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cap[fast_wr, 0, XSCALE_INT_A]
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br[mpacket_tx_loop#]
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.end
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.end
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zero_byte_packet#:
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halt
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