157 lines
3.0 KiB
C
157 lines
3.0 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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/* This file implements the low-level SW-DP interface. */
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#include <libopencm3/stm32/f1/gpio.h>
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#include <stdio.h>
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#include "general.h"
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#include "swdptap.h"
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#include "gdb_packet.h"
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void swdptap_turnaround(uint8_t dir)
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{
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static uint8_t olddir = 0;
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DEBUG("%s", dir ? "\n-> ":"\n<- ");
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/* Don't turnaround if direction not changing */
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if(dir == olddir) return;
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olddir = dir;
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if(dir)
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gpio_set_mode(SWDP_PORT, GPIO_MODE_INPUT,
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GPIO_CNF_INPUT_FLOAT, SWDIO_PIN);
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gpio_set(SWDP_PORT, SWCLK_PIN);
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gpio_clear(SWDP_PORT, SWCLK_PIN);
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if(!dir)
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gpio_set_mode(SWDP_PORT, GPIO_MODE_OUTPUT_10_MHZ,
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GPIO_CNF_OUTPUT_PUSHPULL, SWDIO_PIN);
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}
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uint8_t swdptap_bit_in(void)
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{
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uint8_t ret;
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ret = gpio_get(SWDP_PORT, SWDIO_PIN);
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gpio_set(SWDP_PORT, SWCLK_PIN);
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gpio_clear(SWDP_PORT, SWCLK_PIN);
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DEBUG("%d", ret?1:0);
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return ret;
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}
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void swdptap_bit_out(uint8_t val)
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{
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DEBUG("%d", val);
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gpio_set_val(SWDP_PORT, SWDIO_PIN, val);
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gpio_set(SWDP_PORT, SWCLK_PIN);
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gpio_clear(SWDP_PORT, SWCLK_PIN);
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}
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int swdptap_init(void)
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{
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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_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++) swdptap_bit_out(1);
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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()) 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()) 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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