171 lines
3.4 KiB
C
171 lines
3.4 KiB
C
/*
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* This file is part of the Black Magic Debug project.
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*
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* Copyright (C) 2011 Black Sphere Technologies Ltd.
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* Written by Gareth McMullin <gareth@blacksphere.co.nz>
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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 3 of the License, or
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* (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, see <http://www.gnu.org/licenses/>.
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*/
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/* Quick hack for bit-banging SW-DP interface over FT2232.
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* Intended as proof of concept, not for production.
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*/
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#include <stdio.h>
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#include <assert.h>
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#include <ftdi.h>
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#include "general.h"
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#include "swdptap.h"
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static void swdptap_turnaround(uint8_t dir);
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static uint8_t swdptap_bit_in(void);
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static void swdptap_bit_out(uint8_t val);
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int swdptap_init(void)
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{
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int err;
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assert(ftdic != NULL);
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if((err = ftdi_set_bitmode(ftdic, 0xAB, BITMODE_BITBANG)) != 0) {
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fprintf(stderr, "ftdi_set_bitmode: %d: %s\n",
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err, ftdi_get_error_string(ftdic));
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abort();
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}
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assert(ftdi_write_data(ftdic, (void*)"\xAB\xA8", 2) == 2);
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/* This must be investigated in more detail.
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* As described in STM32 Reference Manual... */
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swdptap_seq_out(0xFFFF, 16);
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swdptap_reset();
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swdptap_seq_out(0xE79E, 16); /* 0b0111100111100111 */
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swdptap_reset();
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swdptap_seq_out(0, 16);
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return 0;
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}
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void swdptap_reset(void)
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{
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swdptap_turnaround(0);
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/* 50 clocks with TMS high */
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for(int i = 0; i < 50; i++)
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swdptap_bit_out(1);
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}
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static void swdptap_turnaround(uint8_t dir)
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{
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static uint8_t olddir = 0;
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platform_buffer_flush();
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if(dir == olddir) return;
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olddir = dir;
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if(dir) /* SWDIO goes to input */
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assert(ftdi_set_bitmode(ftdic, 0xA3, BITMODE_BITBANG) == 0);
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/* One clock cycle */
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ftdi_write_data(ftdic, (void *)"\xAB\xA8", 2);
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if(!dir) /* SWDIO goes to output */
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assert(ftdi_set_bitmode(ftdic, 0xAB, BITMODE_BITBANG) == 0);
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}
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static uint8_t swdptap_bit_in(void)
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{
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uint8_t ret;
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ftdi_read_pins(ftdic, &ret);
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ret &= 0x08;
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ftdi_write_data(ftdic, (void *)"\xA1\xA0", 2);
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return ret;
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}
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static void swdptap_bit_out(uint8_t val)
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{
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uint8_t buf[3] = "\xA0\xA1\xA0";
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if(val) {
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for(int i = 0; i < 3; i++)
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buf[i] |= 0x08;
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}
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platform_buffer_write(buf, 3);
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}
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uint32_t swdptap_seq_in(int ticks)
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{
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uint32_t index = 1;
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uint32_t ret = 0;
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swdptap_turnaround(1);
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while (ticks--) {
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if (swdptap_bit_in())
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ret |= index;
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index <<= 1;
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}
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return ret;
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}
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uint8_t swdptap_seq_in_parity(uint32_t *ret, int ticks)
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{
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uint32_t index = 1;
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uint8_t parity = 0;
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*ret = 0;
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swdptap_turnaround(1);
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while (ticks--) {
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if (swdptap_bit_in()) {
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*ret |= index;
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parity ^= 1;
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}
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index <<= 1;
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}
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if (swdptap_bit_in())
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parity ^= 1;
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return parity;
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}
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void swdptap_seq_out(uint32_t MS, int ticks)
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{
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swdptap_turnaround(0);
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while (ticks--) {
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swdptap_bit_out(MS & 1);
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MS >>= 1;
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}
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}
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void swdptap_seq_out_parity(uint32_t MS, int ticks)
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{
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uint8_t parity = 0;
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swdptap_turnaround(0);
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while (ticks--) {
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swdptap_bit_out(MS & 1);
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parity ^= MS;
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MS >>= 1;
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}
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swdptap_bit_out(parity & 1);
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}
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