path: root/src/target/mips32_pracc.c

/***************************************************************************
 *   Copyright (C) 2008 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 *                                                                         *
 *   Copyright (C) 2008 by David T.L. Wong                                 *
 *                                                                         *
 *   Copyright (C) 2009 by David N. Claffey <dnclaffey@gmail.com>          *
 *                                                                         *
 *   Copyright (C) 2011 by Drasko DRASKOVIC                                *
 *   drasko.draskovic@gmail.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.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.           *
 ***************************************************************************/

/*
 * This version has optimized assembly routines for 32 bit operations:
 * - read word
 * - write word
 * - write array of words
 *
 * One thing to be aware of is that the MIPS32 cpu will execute the
 * instruction after a branch instruction (one delay slot).
 *
 * For example:
 *  LW $2, ($5 +10)
 *  B foo
 *  LW $1, ($2 +100)
 *
 * The LW $1, ($2 +100) instruction is also executed. If this is
 * not wanted a NOP can be inserted:
 *
 *  LW $2, ($5 +10)
 *  B foo
 *  NOP
 *  LW $1, ($2 +100)
 *
 * or the code can be changed to:
 *
 *  B foo
 *  LW $2, ($5 +10)
 *  LW $1, ($2 +100)
 *
 * The original code contained NOPs. I have removed these and moved
 * the branches.
 *
 * These changes result in a 35% speed increase when programming an
 * external flash.
 *
 * More improvement could be gained if the registers do no need
 * to be preserved but in that case the routines should be aware
 * OpenOCD is used as a flash programmer or as a debug tool.
 *
 * Nico Coesel
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <helper/time_support.h>

#include "mips32.h"
#include "mips32_pracc.h"

struct mips32_pracc_context {
	uint32_t *local_oparam;
	int num_oparam;
	const uint32_t *code;
	int code_len;
	uint32_t stack[32];
	int stack_offset;
	struct mips_ejtag *ejtag_info;
};

static int wait_for_pracc_rw(struct mips_ejtag *ejtag_info, uint32_t *ctrl)
{
	uint32_t ejtag_ctrl;
	long long then = timeval_ms();

	/* wait for the PrAcc to become "1" */
	mips_ejtag_set_instr(ejtag_info, EJTAG_INST_CONTROL);

	while (1) {
		ejtag_ctrl = ejtag_info->ejtag_ctrl;
		int retval = mips_ejtag_drscan_32(ejtag_info, &ejtag_ctrl);
		if (retval != ERROR_OK)
			return retval;

		if (ejtag_ctrl & EJTAG_CTRL_PRACC)
			break;

		int timeout = timeval_ms() - then;
		if (timeout > 1000) {
			LOG_DEBUG("DEBUGMODULE: No memory access in progress!");
			return ERROR_JTAG_DEVICE_ERROR;
		}
	}

	*ctrl = ejtag_ctrl;
	return ERROR_OK;
}

/* Shift in control and address for a new processor access, save them in ejtag_info */
static int mips32_pracc_read_ctrl_addr(struct mips_ejtag *ejtag_info)
{
	int retval = wait_for_pracc_rw(ejtag_info, &ejtag_info->pa_ctrl);
	if (retval != ERROR_OK)
		return retval;

	mips_ejtag_set_instr(ejtag_info, EJTAG_INST_ADDRESS);
	ejtag_info->pa_addr = 0;
	retval = mips_ejtag_drscan_32(ejtag_info, &ejtag_info->pa_addr);

	return retval;
}

/* Finish processor access */
static int mips32_pracc_finish(struct mips_ejtag *ejtag_info)
{
	uint32_t ctrl = ejtag_info->ejtag_ctrl & ~EJTAG_CTRL_PRACC;
	mips_ejtag_set_instr(ejtag_info, EJTAG_INST_CONTROL);
	mips_ejtag_drscan_32_out(ejtag_info, ctrl);

	return jtag_execute_queue();
}

int mips32_pracc_clean_text_jump(struct mips_ejtag *ejtag_info)
{
	uint32_t jt_code = MIPS32_J((0x0FFFFFFF & MIPS32_PRACC_TEXT) >> 2);
	int retval;

	/* do 3 0/nops to clean pipeline before a jump to pracc text, NOP in delay slot */
	for (int i = 0; i != 5; i++) {
		/* Wait for pracc */
		retval = wait_for_pracc_rw(ejtag_info, &ejtag_info->pa_ctrl);
		if (retval != ERROR_OK)
			return retval;

		/* Data or instruction out */
		mips_ejtag_set_instr(ejtag_info, EJTAG_INST_DATA);
		uint32_t data = (i == 3) ? jt_code : MIPS32_NOP;
		mips_ejtag_drscan_32_out(ejtag_info, data);

		/* finish pa */
		retval = mips32_pracc_finish(ejtag_info);
		if (retval != ERROR_OK)
			return retval;
	}

	if (ejtag_in