/* * This file is part of the Black Magic Debug project. * * Copyright (C) 2011 Black Sphere Technologies Ltd. * Written by Gareth McMullin * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ /* Quick hack for bit-banging SW-DP interface over FT2232. * Intended as proof of concept, not for production. */ #include #include #include #include "general.h" #include "swdptap.h" static void swdptap_turnaround(uint8_t dir); static uint8_t swdptap_bit_in(void); static void swdptap_bit_out(uint8_t val); int swdptap_init(void) { int err; assert(ftdic != NULL); if((err = ftdi_set_bitmode(ftdic, 0xAB, BITMODE_BITBANG)) != 0) { fprintf(stderr, "ftdi_set_bitmode: %d: %s\n", err, ftdi_get_error_string(ftdic)); abort(); } assert(ftdi_write_data(ftdic, (void*)"\xAB\xA8", 2) == 2); /* This must be investigated in more detail. * As described in STM32 Reference Manual... */ swdptap_seq_out(0xFFFF, 16); swdptap_reset(); swdptap_seq_out(0xE79E, 16); /* 0b0111100111100111 */ swdptap_reset(); swdptap_seq_out(0, 16); return 0; } void swdptap_reset(void) { swdptap_turnaround(0); /* 50 clocks with TMS high */ for(int i = 0; i < 50; i++) swdptap_bit_out(1); } static void swdptap_turnaround(uint8_t dir) { static uint8_t olddir = 0; platform_buffer_flush(); if(dir == olddir) return; olddir = dir; if(dir) /* SWDIO goes to input */ assert(ftdi_set_bitmode(ftdic, 0xA3, BITMODE_BITBANG) == 0); /* One clock cycle */ ftdi_write_data(ftdic, (void *)"\xAB\xA8", 2); if(!dir) /* SWDIO goes to output */ assert(ftdi_set_bitmode(ftdic, 0xAB, BITMODE_BITBANG) == 0); } static uint8_t swdptap_bit_in(void) { uint8_t ret; ftdi_read_pins(ftdic, &ret); ret &= 0x08; ftdi_write_data(ftdic, (void *)"\xA1\xA0", 2); return ret; } static void swdptap_bit_out(uint8_t val) { uint8_t buf[3] = "\xA0\xA1\xA0"; if(val) { for(int i = 0; i < 3; i++) buf[i] |= 0x08; } platform_buffer_write(buf, 3); } uint32_t swdptap_seq_in(int ticks) { uint32_t index = 1; uint32_t ret = 0; swdptap_turnaround(1); while (ticks--) { if (swdptap_bit_in()) ret |= index; index <<= 1; } return ret; } uint8_t swdptap_seq_in_parity(uint32_t *ret, int ticks) { uint32_t index = 1; uint8_t parity = 0; *ret = 0; swdptap_turnaround(1); while (ticks--) { if (swdptap_bit_in()) { *ret |= index; parity ^= 1; } index <<= 1; } if (swdptap_bit_in()) parity ^= 1; return parity; } void swdptap_seq_out(uint32_t MS, int ticks) { swdptap_turnaround(0); while (ticks--) { swdptap_bit_out(MS & 1); MS >>= 1; } } void swdptap_seq_out_parity(uint32_t MS, int ticks) { uint8_t parity = 0; swdptap_turnaround(0); while (ticks--) { swdptap_bit_out(MS & 1); parity ^= MS; MS >>= 1; } swdptap_bit_out(parity & 1); }