1 /***************************************************************************
2 * Copyright (C) 2005 by Dominic Rath *
3 * Dominic.Rath@gmx.de *
5 * Copyright (C) 2007,2008 Øyvind Harboe *
6 * oyvind.harboe@zylin.com *
8 * This program is free software; you can redistribute it and/or modify *
9 * it under the terms of the GNU General Public License as published by *
10 * the Free Software Foundation; either version 2 of the License, or *
11 * (at your option) any later version. *
13 * This program is distributed in the hope that it will be useful, *
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16 * GNU General Public License for more details. *
18 * You should have received a copy of the GNU General Public License *
19 * along with this program; if not, write to the *
20 * Free Software Foundation, Inc., *
21 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
22 ***************************************************************************/
28 #define INCLUDE_JTAG_INTERFACE_H
32 * Function bitbang_stableclocks
33 * issues a number of clock cycles while staying in a stable state.
34 * Because the TMS value required to stay in the RESET state is a 1, whereas
35 * the TMS value required to stay in any of the other stable states is a 0,
36 * this function checks the current stable state to decide on the value of TMS
39 static void bitbang_stableclocks(int num_cycles);
42 bitbang_interface_t *bitbang_interface;
44 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
46 * Set this to 1 and str912 reset halt will fail.
48 * If someone can submit a patch with an explanation it will be greatly
49 * appreciated, but as far as I can tell (ØH) DCLK is generated upon
50 * clk=0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
51 * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
52 * state". With hardware there is no such thing as *while* in a state. There
53 * are only edges. So clk => 0 is in fact a very subtle state transition that
54 * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
56 * For "reset halt" the last thing that happens before srst is asserted
57 * is that the breakpoint is set up. If DCLK is not wiggled one last
58 * time before the reset, then the breakpoint is not set up and
59 * "reset halt" will fail to halt.
62 #define CLOCK_IDLE() 0
65 /* The bitbang driver leaves the TCK 0 when in idle */
66 static void bitbang_end_state(tap_state_t state)
68 if (tap_is_state_stable(state))
69 tap_set_end_state(state);
72 LOG_ERROR("BUG: %i is not a valid end state", state);
77 static void bitbang_state_move(int skip)
80 u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
81 int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
83 for (i = skip; i < tms_count; i++)
85 tms = (tms_scan >> i) & 1;
86 bitbang_interface->write(0, tms, 0);
87 bitbang_interface->write(1, tms, 0);
89 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
91 tap_set_state(tap_get_end_state());
94 static void bitbang_path_move(pathmove_command_t *cmd)
96 int num_states = cmd->num_states;
103 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
107 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
113 LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
117 bitbang_interface->write(0, tms, 0);
118 bitbang_interface->write(1, tms, 0);
120 tap_set_state(cmd->path[state_count]);
125 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
127 tap_set_end_state(tap_get_state());
130 static void bitbang_runtest(int num_cycles)
134 tap_state_t saved_end_state = tap_get_end_state();
136 /* only do a state_move when we're not already in IDLE */
137 if (tap_get_state() != TAP_IDLE)
139 bitbang_end_state(TAP_IDLE);
140 bitbang_state_move(0);
143 /* execute num_cycles */
144 for (i = 0; i < num_cycles; i++)
146 bitbang_interface->write(0, 0, 0);
147 bitbang_interface->write(1, 0, 0);
149 bitbang_interface->write(CLOCK_IDLE(), 0, 0);
151 /* finish in end_state */
152 bitbang_end_state(saved_end_state);
153 if (tap_get_state() != tap_get_end_state())
154 bitbang_state_move(0);
158 static void bitbang_stableclocks(int num_cycles)
160 int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
163 /* send num_cycles clocks onto the cable */
164 for (i = 0; i < num_cycles; i++)
166 bitbang_interface->write(1, tms, 0);
167 bitbang_interface->write(0, tms, 0);
173 static void bitbang_scan(bool ir_scan, enum scan_type type, u8 *buffer, int scan_size)
175 tap_state_t saved_end_state = tap_get_end_state();
178 if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
181 bitbang_end_state(TAP_IRSHIFT);
183 bitbang_end_state(TAP_DRSHIFT);
185 bitbang_state_move(0);
186 bitbang_end_state(saved_end_state);
189 for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
192 int tms=(bit_cnt==scan_size-1) ? 1 : 0;
195 int bcval=1<<(bit_cnt % 8);
197 /* if we're just reading the scan, but don't care about the output
198 * default to outputting 'low', this also makes valgrind traces more readable,
199 * as it removes the dependency on an uninitialised value
202 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
205 bitbang_interface->write(0, tms, tdi);
208 val=bitbang_interface->read();
210 bitbang_interface->write(1, tms, tdi);
212 if (type != SCAN_OUT)
215 buffer[bytec] |= bcval;
217 buffer[bytec] &= ~bcval;
221 if (tap_get_state() != tap_get_end_state())
223 /* we *KNOW* the above loop transitioned out of
224 * the shift state, so we skip the first state
225 * and move directly to the end state.
227 bitbang_state_move(1);
231 int bitbang_execute_queue(void)
233 jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
239 if (!bitbang_interface)
241 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
245 /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
246 * that wasn't handled by a caller-provided error handler
250 if(bitbang_interface->blink)
251 bitbang_interface->blink(1);
258 #ifdef _DEBUG_JTAG_IO_
259 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
261 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
263 tap_set_state(TAP_RESET);
265 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
268 #ifdef _DEBUG_JTAG_IO_
269 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
271 if (cmd->cmd.runtest->end_state != TAP_INVALID)
272 bitbang_end_state(cmd->cmd.runtest->end_state);
273 bitbang_runtest(cmd->cmd.runtest->num_cycles);
276 case JTAG_STABLECLOCKS:
277 /* this is only allowed while in a stable state. A check for a stable
278 * state was done in jtag_add_clocks()
280 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
284 #ifdef _DEBUG_JTAG_IO_
285 LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
287 if (cmd->cmd.statemove->end_state != TAP_INVALID)
288 bitbang_end_state(cmd->cmd.statemove->end_state);
289 bitbang_state_move(0);
292 #ifdef _DEBUG_JTAG_IO_
293 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
294 tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
296 bitbang_path_move(cmd->cmd.pathmove);
299 #ifdef _DEBUG_JTAG_IO_
300 LOG_DEBUG("%s scan end in %s", (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state) );
302 if (cmd->cmd.scan->end_state != TAP_INVALID)
303 bitbang_end_state(cmd->cmd.scan->end_state);
304 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
305 type = jtag_scan_type(cmd->cmd.scan);
306 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
307 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
308 retval = ERROR_JTAG_QUEUE_FAILED;
313 #ifdef _DEBUG_JTAG_IO_
314 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
316 jtag_sleep(cmd->cmd.sleep->us);
319 LOG_ERROR("BUG: unknown JTAG command type encountered");
324 if(bitbang_interface->blink)
325 bitbang_interface->blink(0);