diff options
Diffstat (limited to 'src/jtag/drivers/bitbang.c')
| -rw-r--r-- | src/jtag/drivers/bitbang.c | 325 |
1 files changed, 325 insertions, 0 deletions
diff --git a/src/jtag/drivers/bitbang.c b/src/jtag/drivers/bitbang.c new file mode 100644 index 00000000..69c17298 --- /dev/null +++ b/src/jtag/drivers/bitbang.c @@ -0,0 +1,325 @@ +/*************************************************************************** + * Copyright (C) 2005 by Dominic Rath * + * Dominic.Rath@gmx.de * + * * + * Copyright (C) 2007,2008 Øyvind Harboe * + * oyvind.harboe@zylin.com * + * * + * 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 2 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, write to the * + * Free Software Foundation, Inc., * + * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * + ***************************************************************************/ +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "bitbang.h" +#include "interface.h" +#include "commands.h" + +/** + * Function bitbang_stableclocks + * issues a number of clock cycles while staying in a stable state. + * Because the TMS value required to stay in the RESET state is a 1, whereas + * the TMS value required to stay in any of the other stable states is a 0, + * this function checks the current stable state to decide on the value of TMS + * to use. + */ +static void bitbang_stableclocks(int num_cycles); + + +struct bitbang_interface *bitbang_interface; + +/* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work! + * + * Set this to 1 and str912 reset halt will fail. + * + * If someone can submit a patch with an explanation it will be greatly + * appreciated, but as far as I can tell (ØH) DCLK is generated upon + * clk = 0 in TAP_IDLE. Good luck deducing that from the ARM documentation! + * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE + * state". With hardware there is no such thing as *while* in a state. There + * are only edges. So clk => 0 is in fact a very subtle state transition that + * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#& + * + * For "reset halt" the last thing that happens before srst is asserted + * is that the breakpoint is set up. If DCLK is not wiggled one last + * time before the reset, then the breakpoint is not set up and + * "reset halt" will fail to halt. + * + */ +#define CLOCK_IDLE() 0 + + +/* The bitbang driver leaves the TCK 0 when in idle */ +static void bitbang_end_state(tap_state_t state) +{ + if (tap_is_state_stable(state)) + tap_set_end_state(state); + else + { + LOG_ERROR("BUG: %i is not a valid end state", state); + exit(-1); + } +} + +static void bitbang_state_move(int skip) +{ + int i = 0, tms = 0; + uint8_t tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state()); + int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state()); + + for (i = skip; i < tms_count; i++) + { + tms = (tms_scan >> i) & 1; + bitbang_interface->write(0, tms, 0); + bitbang_interface->write(1, tms, 0); + } + bitbang_interface->write(CLOCK_IDLE(), tms, 0); + + tap_set_state(tap_get_end_state()); +} + +static void bitbang_path_move(struct pathmove_command *cmd) +{ + int num_states = cmd->num_states; + int state_count; + int tms = 0; + + state_count = 0; + while (num_states) + { + if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count]) + { + tms = 0; + } + else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count]) + { + tms = 1; + } + else + { + LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count])); + exit(-1); + } + + bitbang_interface->write(0, tms, 0); + bitbang_interface->write(1, tms, 0); + + tap_set_state(cmd->path[state_count]); + state_count++; + num_states--; + } + + bitbang_interface->write(CLOCK_IDLE(), tms, 0); + + tap_set_end_state(tap_get_state()); +} + +static void bitbang_runtest(int num_cycles) +{ + int i; + + tap_state_t saved_end_state = tap_get_end_state(); + + /* only do a state_move when we're not already in IDLE */ + if (tap_get_state() != TAP_IDLE) + { + bitbang_end_state(TAP_IDLE); + bitbang_state_move(0); + } + + /* execute num_cycles */ + for (i = 0; i < num_cycles; i++) + { + bitbang_interface->write(0, 0, 0); + bitbang_interface->write(1, 0, 0); + } + bitbang_interface->write(CLOCK_IDLE(), 0, 0); + + /* finish in end_state */ + bitbang_end_state(saved_end_state); + if (tap_get_state() != tap_get_end_state()) + bitbang_state_move(0); +} + + +static void bitbang_stableclocks(int num_cycles) +{ + int tms = (tap_get_state() == TAP_RESET ? 1 : 0); + int i; + + /* send num_cycles clocks onto the cable */ + for (i = 0; i < num_cycles; i++) + { + bitbang_interface->write(1, tms, 0); + bitbang_interface->write(0, tms, 0); + } +} + + + +static void bitbang_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size) +{ + tap_state_t saved_end_state = tap_get_end_state(); + int bit_cnt; + + if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT)))) + { + if (ir_scan) + bitbang_end_state(TAP_IRSHIFT); + else + bitbang_end_state(TAP_DRSHIFT); + + bitbang_state_move(0); + bitbang_end_state(saved_end_state); + } + + for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++) + { + int val = 0; + int tms = (bit_cnt == scan_size-1) ? 1 : 0; + int tdi; + int bytec = bit_cnt/8; + int bcval = 1 << (bit_cnt % 8); + + /* if we're just reading the scan, but don't care about the output + * default to outputting 'low', this also makes valgrind traces more readable, + * as it removes the dependency on an uninitialised value + */ + tdi = 0; + if ((type != SCAN_IN) && (buffer[bytec] & bcval)) + tdi = 1; + + bitbang_interface->write(0, tms, tdi); + + if (type != SCAN_OUT) + val = bitbang_interface->read(); + + bitbang_interface->write(1, tms, tdi); + + if (type != SCAN_OUT) + { + if (val) + buffer[bytec] |= bcval; + else + buffer[bytec] &= ~bcval; + } + } + + if (tap_get_state() != tap_get_end_state()) + { + /* we *KNOW* the above loop transitioned out of + * the shift state, so we skip the first state + * and move directly to the end state. + */ + bitbang_state_move(1); + } +} + +int bitbang_execute_queue(void) +{ + struct jtag_command *cmd = jtag_command_queue; /* currently processed command */ + int scan_size; + enum scan_type type; + uint8_t *buffer; + int retval; + + if (!bitbang_interface) + { + LOG_ERROR("BUG: Bitbang interface called, but not yet initialized"); + exit(-1); + } + + /* return ERROR_OK, unless a jtag_read_buffer returns a failed check + * that wasn't handled by a caller-provided error handler + */ + retval = ERROR_OK; + + if (bitbang_interface->blink) + bitbang_interface->blink(1); + + while (cmd) + { + switch (cmd->type) + { + case JTAG_RESET: +#ifdef _DEBUG_JTAG_IO_ + LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst); +#endif + if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST))) + { + tap_set_state(TAP_RESET); + } + bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst); + break; + case JTAG_RUNTEST: +#ifdef _DEBUG_JTAG_IO_ + LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state)); +#endif + bitbang_end_state(cmd->cmd.runtest->end_state); + bitbang_runtest(cmd->cmd.runtest->num_cycles); + break; + + case JTAG_STABLECLOCKS: + /* this is only allowed while in a stable state. A check for a stable + * state was done in jtag_add_clocks() + */ + bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles); + break; + + case JTAG_STATEMOVE: +#ifdef _DEBUG_JTAG_IO_ + LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state)); +#endif + bitbang_end_state(cmd->cmd.statemove->end_state); + bitbang_state_move(0); + break; + case JTAG_PATHMOVE: +#ifdef _DEBUG_JTAG_IO_ + LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states, + tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1])); +#endif + bitbang_path_move(cmd->cmd.pathmove); + break; + case JTAG_SCAN: +#ifdef _DEBUG_JTAG_IO_ + LOG_DEBUG("%s scan end in %s", (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state)); +#endif + bitbang_end_state(cmd->cmd.scan->end_state); + scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer); + type = jtag_scan_type(cmd->cmd.scan); + bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size); + if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK) + retval = ERROR_JTAG_QUEUE_FAILED; + if (buffer) + free(buffer); + break; + case JTAG_SLEEP: +#ifdef _DEBUG_JTAG_IO_ + LOG_DEBUG("sleep %" PRIi32, cmd->cmd.sleep->us); +#endif + jtag_sleep(cmd->cmd.sleep->us); + break; + default: + LOG_ERROR("BUG: unknown JTAG command type encountered"); + exit(-1); + } + cmd = cmd->next; + } + if (bitbang_interface->blink) + bitbang_interface->blink(0); + + return retval; +} |