[ 2798198 ] The Minimal Parallel Port JTAG Cable (Yen Rui)
git-svn-id: https://urjtag.svn.sourceforge.net/svnroot/urjtag/trunk@1647 b68d4a1b-bc3d-0410-92ed-d4ac073336b7master
Arnim Läuger
16 years ago
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/*
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* $Id$
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*
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* Minimal Parallel Port JTAG Cable Driver
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* Copyright © 2009 Yen Rui
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*
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* The Minimal Parallel Port JTAG Cable is a cheap and easy-to-make cable
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* that only uses the four fundamental JTAG signals (TMS, TCD, TDI and TDO),
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* i.e. it does NOT use the TRST signal. The Minimal Parallel Port JTAG
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* Cable is a strict subset of the Macraigor Wiggler JTAG Cable, i.e. the
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* more expensive Macraigor Wiggler JTAG Cable can be a drop-in replacement
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* of the Minimal Parallel Port JTAG Cable.
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*
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* http://oldwiki.openwrt.org/OpenWrtDocs(2f)Customizing(2f)Hardware(2f)JTAG_Cable.html
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*
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* This driver does not modify the state of any other parallel port pins.
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*
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*/
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#include <sysdep.h>
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#include <urjtag/cable.h>
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#include <urjtag/parport.h>
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#include <urjtag/chain.h>
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#include "generic.h"
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#include "generic_parport.h"
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/*
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* data D[7:0] (pins 9:2)
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*/
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#define TMS 1
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#define TCK 2
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#define TDI 3
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/*
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* 7 - BUSY (pin 11)
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* 6 - ACK (pin 10)
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* 5 - PE (pin 12)
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* 4 - SEL (pin 13)
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* 3 - ERROR (pin 15)
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*/
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#define TDO 7
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/* FIXME: having a static variable like this is probably not thread safe */
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static unsigned char unused_bits;
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static int
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minimal_init (urj_cable_t *cable)
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{
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int data;
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if (urj_tap_parport_open (cable->link.port))
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return URJ_STATUS_FAIL;
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if ((data = urj_tap_parport_get_data (cable->link.port)) < 0)
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return URJ_STATUS_FAIL;
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/* remember state of all parallel port pins except TDI, TCK and TMS */
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unused_bits = data & (~((1 << TDI) | (1 << TCK) | (1 << TMS)));
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/* copy data into PARAM_SIGNALS (cable) while faking URJ_POD_CS_TRST */
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PARAM_SIGNALS (cable) = URJ_POD_CS_TRST;
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PARAM_SIGNALS (cable) |= (data & TDI) ? URJ_POD_CS_TDI : 0;
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PARAM_SIGNALS (cable) |= (data & TCK) ? URJ_POD_CS_TCK : 0;
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PARAM_SIGNALS (cable) |= (data & TMS) ? URJ_POD_CS_TMS : 0;
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return URJ_STATUS_OK;
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}
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static void
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minimal_clock (urj_cable_t *cable, int tms, int tdi, int n)
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{
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int i;
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tms = tms ? 1 : 0;
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tdi = tdi ? 1 : 0;
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for (i = 0; i < n; i++)
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{
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urj_tap_parport_set_data (cable->link.port,
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(tms << TMS) | (0 << TCK) | (tdi << TDI) |
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unused_bits);
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urj_tap_cable_wait (cable);
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urj_tap_parport_set_data (cable->link.port,
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(tms << TMS) | (1 << TCK) | (tdi << TDI) |
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unused_bits);
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urj_tap_cable_wait (cable);
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}
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/* do not touch URJ_POD_CS_TRST in PARAM_SIGNALS (cable) */
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PARAM_SIGNALS (cable) &= ~(URJ_POD_CS_TMS | URJ_POD_CS_TDI);
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PARAM_SIGNALS (cable) |= URJ_POD_CS_TCK;
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PARAM_SIGNALS (cable) |= tms ? URJ_POD_CS_TMS : 0;
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PARAM_SIGNALS (cable) |= tdi ? URJ_POD_CS_TDI : 0;
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}
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static int
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minimal_get_tdo (urj_cable_t *cable)
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{
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urj_tap_parport_set_data (cable->link.port, (0 << TCK) | unused_bits);
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PARAM_SIGNALS (cable) &=
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~(URJ_POD_CS_TDI | URJ_POD_CS_TCK | URJ_POD_CS_TMS);
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urj_tap_cable_wait (cable);
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return (urj_tap_parport_get_status (cable->link.port) >> TDO) & 1;
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}
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static int
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minimal_set_signal (urj_cable_t *cable, int mask, int val)
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{
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int prev_sigs = PARAM_SIGNALS (cable);
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/* only these signals can be modified */
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mask &= (URJ_POD_CS_TDI | URJ_POD_CS_TCK | URJ_POD_CS_TMS | URJ_POD_CS_TRST);
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if (mask != 0)
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{
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unsigned char data = 0;
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int sigs = (prev_sigs & ~mask) | (val & mask);
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data |= (sigs & URJ_POD_CS_TDI) ? (1 << TDI) : 0;
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data |= (sigs & URJ_POD_CS_TCK) ? (1 << TCK) : 0;
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data |= (sigs & URJ_POD_CS_TMS) ? (1 << TMS) : 0;
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/* do not actually set TRST on parallel port ... */
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//data |= (sigs & URJ_POD_CS_TRST) ? (1 << TRST) : 0;
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urj_tap_parport_set_data (cable->link.port, data | unused_bits);
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/* ... although TRST can be marked as set in PARAM_SIGNALS (cable) */
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PARAM_SIGNALS (cable) = sigs;
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}
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return prev_sigs;
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}
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urj_cable_driver_t urj_tap_cable_minimal_driver = {
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"Minimal",
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N_("Minimal Parallel Port JTAG Cable"),
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URJ_CABLE_DEVICE_PARPORT,
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{ .parport = urj_tap_cable_generic_parport_connect, },
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urj_tap_cable_generic_disconnect,
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urj_tap_cable_generic_parport_free,
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minimal_init,
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urj_tap_cable_generic_parport_done,
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urj_tap_cable_generic_set_frequency,
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minimal_clock,
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minimal_get_tdo,
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urj_tap_cable_generic_transfer,
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minimal_set_signal,
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urj_tap_cable_generic_get_signal,
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urj_tap_cable_generic_flush_one_by_one,
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urj_tap_cable_generic_parport_help
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};
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