arm_debug: optimize DP and AP reads over JTAG

[openocd.git] / src / target / adi_v5_jtag.c

/***************************************************************************
 *   Copyright (C) 2006 by Magnus Lundin
 *   lundin@mlu.mine.nu
 *
 *   Copyright (C) 2008 by Spencer Oliver
 *   spen@spen-soft.co.uk
 *
 *   Copyright (C) 2009 by Oyvind Harboe
 *   oyvind.harboe@zylin.com
 *
 *   Copyright (C) 2009-2010 by David Brownell
 *
 *   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.
 ***************************************************************************/

/**
 * @file
 * This file implements JTAG transport support for cores implementing
 the ARM Debug Interface version 5 (ADIv5).
 */

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

#include "arm.h"
#include "arm_adi_v5.h"
#include <helper/time_support.h>

/* JTAG instructions/registers for JTAG-DP and SWJ-DP */
#define JTAG_DP_ABORT           0x8
#define JTAG_DP_DPACC           0xA
#define JTAG_DP_APACC           0xB
#define JTAG_DP_IDCODE          0xE

/* three-bit ACK values for DPACC and APACC reads */
#define JTAG_ACK_OK_FAULT       0x2
#define JTAG_ACK_WAIT           0x1

static int jtag_ap_q_abort(struct adiv5_dap *dap, uint8_t *ack);

/***************************************************************************
 *
 * DPACC and APACC scanchain access through JTAG-DP (or SWJ-DP)
 *
***************************************************************************/

/**
 * Scan DPACC or APACC using target ordered uint8_t buffers.  No endianness
 * conversions are performed.  See section 4.4.3 of the ADIv5 spec, which
 * discusses operations which access these registers.
 *
 * Note that only one scan is performed.  If RnW is set, a separate scan
 * will be needed to collect the data which was read; the "invalue" collects
 * the posted result of a preceding operation, not the current one.
 *
 * @param dap the DAP
 * @param instr JTAG_DP_APACC (AP access) or JTAG_DP_DPACC (DP access)
 * @param reg_addr two significant bits; A[3:2]; for APACC access, the
 *      SELECT register has more addressing bits.
 * @param RnW false iff outvalue will be written to the DP or AP
 * @param outvalue points to a 32-bit (little-endian) integer
 * @param invalue NULL, or points to a 32-bit (little-endian) integer
 * @param ack points to where the three bit JTAG_ACK_* code will be stored
 * @param memaccess_tck number of idle cycles to add after AP access
 */

static int adi_jtag_dp_scan(struct adiv5_dap *dap,
                uint8_t instr, uint8_t reg_addr, uint8_t RnW,
                uint8_t *outvalue, uint8_t *invalue, uint8_t *ack,
                uint32_t memaccess_tck)
{
        struct jtag_tap *tap = dap->tap;
        struct scan_field fields[2];
        uint8_t out_addr_buf;
        int retval;

        retval = arm_jtag_set_instr(tap, instr, NULL, TAP_IDLE);
        if (retval != ERROR_OK)
                return retval;

        /* Scan out a read or write operation using some DP or AP register.
         * For APACC access with any sticky error flag set, this is discarded.
         */
        fields[0].num_bits = 3;
        buf_set_u32(&out_addr_buf, 0, 3, ((reg_addr >> 1) & 0x6) | (RnW & 0x1));
        fields[0].out_value = &out_addr_buf;
        fields[0].in_value = ack;

        /* NOTE: if we receive JTAG_ACK_WAIT, the previous operation did not
         * complete; data we write is discarded, data we read is unpredictable.
         * When overrun detect is active, STICKYORUN is set.
         */

        fields[1].num_bits = 32;
        fields[1].out_value = outvalue;
        fields[1].in_value = invalue;

        jtag_add_dr_scan(tap, 2, fields, TAP_IDLE);

        /* Add specified number of tck clocks after starting memory bus
         * access, giving the hardware time to complete the access.
         * They provide more time for the (MEM) AP to complete the read ...
         * See "Minimum Response Time" for JTAG-DP, in the ADIv5 spec.
         */
        if ((instr == JTAG_DP_APACC)
                        && ((reg_addr == MEM_AP_REG_DRW)
                                || ((reg_addr & 0xF0) == MEM_AP_REG_BD0))
                        && memaccess_tck != 0)
                jtag_add_runtest(memaccess_tck, TAP_IDLE);

        return ERROR_OK;
}

/**
 * Scan DPACC or APACC out and in from host ordered uint32_t buffers.
 * This is exactly like adi_jtag_dp_scan(), except that endianness
 * conversions are performed (so the types of invalue and outvalue
 * must be different).
 */
static int adi_jtag_dp_scan_u32(struct adiv5_dap *dap,
                uint8_t instr, uint8_t reg_addr, uint8_t RnW,
                uint32_t outvalue, uint32_t *invalue, uint8_t *ack,
                uint32_t memaccess_tck)
{
        uint8_t out_value_buf[4];
        int retval;

        buf_set_u32(out_value_buf, 0, 32, outvalue);

        retval = adi_jtag_dp_scan(dap, instr, reg_addr, RnW,
                        out_value_buf, (uint8_t *)invalue, ack, memaccess_tck);
        if (retval != ERROR_OK)
                return retval;

        if (invalue)
                jtag_add_callback(arm_le_to_h_u32,
                                (jtag_callback_data_t) invalue);

        return retval;
}

static void adi_jtag_finish_read(struct adiv5_dap *dap)
{
        if (dap->last_read != NULL) {
                adi_jtag_dp_scan_u32(dap, JTAG_DP_DPACC,
                                DP_RDBUFF, DPAP_READ, 0, dap->last_read, &dap->ack, 0);
                dap->last_read = NULL;
        }
}

static int adi_jtag_scan_inout_check_u32(struct adiv5_dap *dap,
                uint8_t instr, uint8_t reg_addr, uint8_t RnW,
                uint32_t outvalue, uint32_t *invalue, uint32_t memaccess_tck)
{
        int retval;

        /* Issue the read or write */
        retval = adi_jtag_dp_scan_u32(dap, instr, reg_addr,
                        RnW, outvalue, NULL, NULL, memaccess_tck);
        if (retval != ERROR_OK)
                return retval;

        /* For reads,  collect posted value; RDBUFF has no other effect.
         * Assumes read gets acked with OK/FAULT, and CTRL_STAT says "OK".
         */
        if ((RnW == DPAP_READ) && (invalue != NULL))
                retval = adi_jtag_dp_scan_u32(dap, JTAG_DP_DPACC,
                                DP_RDBUFF, DPAP_READ, 0, invalue, &dap->ack, 0);
        return retval;
}

static int jtagdp_transaction_endcheck(struct adiv5_dap *dap)
{
        int retval;
        uint32_t ctrlstat;

        /* too expensive to call keep_alive() here */

        /* Here be dragons!
         *
         * It is easy to be in a JTAG clock range where the target
         * is not operating in a stable fashion. This happens
         * for a few reasons:
         *
         * - the user may construct a simple test case to try to see
         * if a higher JTAG clock works to eke out more performance.
         * This simple case may pass, but more complex situations can
         * fail.
         *
         * - The mostly works JTAG clock rate and the complete failure
         * JTAG clock rate may be as much as 2-4x apart. This seems
         * to be especially true on RC oscillator driven parts.
         *
         * So: even if calling adi_jtag_scan_inout_check_u32() multiple
         * times here seems to "make things better here", it is just
         * hiding problems with too high a JTAG clock.
         *
         * Note that even if some parts have RCLK/RTCK, that doesn't
         * mean that RCLK/RTCK is the *correct* rate to run the JTAG
         * interface at, i.e. RCLK/RTCK rates can be "too high", especially
         * before the RC oscillator phase is not yet complete.
         */

        /* Post CTRL/STAT read; discard any previous posted read value
         * but collect its ACK status.
         */
        retval = adi_jtag_scan_inout_check_u32(dap, JTAG_DP_DPACC,
                        DP_CTRL_STAT, DPAP_READ, 0, &ctrlstat, 0);
        if (retval != ERROR_OK)
                return retval;
        retval = jtag_execute_queue();
        if (retval != ERROR_OK)
                return retval;

        dap->ack = dap->ack & 0x7;

        /* common code path avoids calling timeval_ms() */
        if (dap->ack != JTAG_ACK_OK_FAULT) {
                long long then = timeval_ms();

                while (dap->ack != JTAG_ACK_OK_FAULT) {
                        if (dap->ack == JTAG_ACK_WAIT) {
                                if ((timeval_ms()-then) > 1000) {
                                        LOG_WARNING("Timeout (1000ms) waiting "
                                                "for ACK=OK/FAULT "
                                                "in JTAG-DP transaction - aborting");

                                        uint8_t ack;
                                        int abort_ret = jtag_ap_q_abort(dap, &ack);

                                        if (abort_ret != 0)
                                                LOG_WARNING("Abort failed : return=%d ack=%d", abort_ret, ack);

                                        return ERROR_JTAG_DEVICE_ERROR;
                                }
                        } else {
                                LOG_WARNING("Invalid ACK %#x "
                                                "in JTAG-DP transaction",
                                                dap->ack);
                                return ERROR_JTAG_DEVICE_ERROR;
                        }

                        retval = adi_jtag_scan_inout_check_u32(dap, JTAG_DP_DPACC,
                                        DP_CTRL_STAT, DPAP_READ, 0, &ctrlstat, 0);
                        if (retval != ERROR_OK)
                                return retval;
                        retval = jtag_execute_queue();
                        if (retval != ERROR_OK)
                                return retval;
                        dap->ack = dap->ack & 0x7;
                }
        }

        /* REVISIT also STICKYCMP, for pushed comparisons (nyet used) */

        /* Check for STICKYERR and STICKYORUN */
        if (ctrlstat & (SSTICKYORUN | SSTICKYERR)) {
                LOG_DEBUG("jtag-dp: CTRL/STAT error, 0x%" PRIx32, ctrlstat);
                /* Check power to debug regions */
                if ((ctrlstat & 0xf0000000) != 0xf0000000) {
                        LOG_ERROR("Debug regions are unpowered, an unexpected reset might have happened");
                        return ERROR_JTAG_DEVICE_ERROR;
                } else {
                        if (ctrlstat & SSTICKYORUN)
                                LOG_ERROR("JTAG-DP OVERRUN - check clock, "
                                        "memaccess, or reduce jtag speed");

                        if (ctrlstat & SSTICKYERR)
                                LOG_ERROR("JTAG-DP STICKY ERROR");

                        /* Clear Sticky Error Bits */
                        retval = adi_jtag_scan_inout_check_u32(dap, JTAG_DP_DPACC,
                                        DP_CTRL_STAT, DPAP_WRITE,
                                        dap->dp_ctrl_stat | SSTICKYORUN
                                                | SSTICKYERR, NULL, 0);
                        if (retval != ERROR_OK)
                                return retval;
                        retval = adi_jtag_scan_inout_check_u32(dap, JTAG_DP_DPACC,
                                        DP_CTRL_STAT, DPAP_READ, 0, &ctrlstat, 0);
                        if (retval != ERROR_OK)
                                return retval;
                        retval = jtag_execute_queue();
                        if (retval != ERROR_OK)
                                return retval;

                        LOG_DEBUG("jtag-dp: CTRL/STAT 0x%" PRIx32, ctrlstat);
                }
                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return retval;
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

/*--------------------------------------------------------------------------*/

static int jtag_dp_q_read(struct adiv5_dap *dap, unsigned reg,
                uint32_t *data)
{
        int retval =  adi_jtag_dp_scan_u32(dap, JTAG_DP_DPACC, reg,
                        DPAP_READ, 0, dap->last_read, &dap->ack, 0);
        dap->last_read = data;
        return retval;
}

static int jtag_dp_q_write(struct adiv5_dap *dap, unsigned reg,
                uint32_t data)
{
        int retval =  adi_jtag_dp_scan_u32(dap, JTAG_DP_DPACC,
                        reg, DPAP_WRITE, data, dap->last_read, &dap->ack, 0);
        dap->last_read = NULL;
        return retval;
}

/** Select the AP register bank matching bits 7:4 of reg. */
static int jtag_ap_q_bankselect(struct adiv5_ap *ap, unsigned reg)
{
        struct adiv5_dap *dap = ap->dap;
        uint32_t select = ((uint32_t)ap->ap_num << 24) | (reg & 0x000000F0);

        if (select == dap->select)
                return ERROR_OK;

        dap->select = select;

        return jtag_dp_q_write(dap, DP_SELECT, select);
}

static int jtag_ap_q_read(struct adiv5_ap *ap, unsigned reg,
                uint32_t *data)
{
        int retval = jtag_ap_q_bankselect(ap, reg);
        if (retval != ERROR_OK)
                return retval;

        retval =  adi_jtag_dp_scan_u32(ap->dap, JTAG_DP_APACC, reg,
                        DPAP_READ, 0, ap->dap->last_read, &ap->dap->ack,
                        ap->memaccess_tck);
        ap->dap->last_read = data;

        return retval;
}

static int jtag_ap_q_write(struct adiv5_ap *ap, unsigned reg,
                uint32_t data)
{
        int retval = jtag_ap_q_bankselect(ap, reg);
        if (retval != ERROR_OK)
                return retval;

        retval =  adi_jtag_dp_scan_u32(ap->dap, JTAG_DP_APACC, reg,
                        DPAP_WRITE, data, ap->dap->last_read, &ap->dap->ack,
                        ap->memaccess_tck);
        ap->dap->last_read = NULL;
        return retval;
}

static int jtag_ap_q_abort(struct adiv5_dap *dap, uint8_t *ack)
{
        /* for JTAG, this is the only valid ABORT register operation */
        return adi_jtag_dp_scan_u32(dap, JTAG_DP_ABORT,
                        0, DPAP_WRITE, 1, NULL, ack, 0);
}

static int jtag_dp_run(struct adiv5_dap *dap)
{
        adi_jtag_finish_read(dap);
        return jtagdp_transaction_endcheck(dap);
}

/* FIXME don't export ... just initialize as
 * part of DAP setup
*/
const struct dap_ops jtag_dp_ops = {
        .queue_dp_read       = jtag_dp_q_read,
        .queue_dp_write      = jtag_dp_q_write,
        .queue_ap_read       = jtag_ap_q_read,
        .queue_ap_write      = jtag_ap_q_write,
        .queue_ap_abort      = jtag_ap_q_abort,
        .run                 = jtag_dp_run,
};


static const uint8_t swd2jtag_bitseq[] = {
        /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
         * putting both JTAG and SWD logic into reset state.
         */
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        /* Switching equence disables SWD and enables JTAG
         * NOTE: bits in the DP's IDCODE can expose the need for
         * the old/deprecated sequence (0xae 0xde).
         */
        0x3c, 0xe7,
        /* At least 50 TCK/SWCLK cycles with TMS/SWDIO high,
         * putting both JTAG and SWD logic into reset state.
         * NOTE:  some docs say "at least 5".
         */
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
};

/** Put the debug link into JTAG mode, if the target supports it.
 * The link's initial mode may be either SWD or JTAG.
 *
 * @param target Enters JTAG mode (if possible).
 *
 * Note that targets implemented with SW-DP do not support JTAG, and
 * that some targets which could otherwise support it may have been
 * configured to disable JTAG signaling
 *
 * @return ERROR_OK or else a fault code.
 */
int dap_to_jtag(struct target *target)
{
        int retval;

        LOG_DEBUG("Enter JTAG mode");

        /* REVISIT it's nasty to need to make calls to a "jtag"
         * subsystem if the link isn't in JTAG mode...
         */

        retval = jtag_add_tms_seq(8 * sizeof(swd2jtag_bitseq),
                        swd2jtag_bitseq, TAP_RESET);
        if (retval == ERROR_OK)
                retval = jtag_execute_queue();

        /* REVISIT set up the DAP's ops vector for JTAG mode. */

        return retval;
}