dummy.c

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// SPDX-License-Identifier: GPL-2.0-or-later
 
/***************************************************************************
 *   Copyright (C) 2008 by Øyvind Harboe                                   *
 *   oyvind.harboe@zylin.com                                               *
 ***************************************************************************/
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include <jtag/interface.h>
#include "bitbang.h"
#include "hello.h"
 
/* my private tap controller state, which tracks state for calling code */
static tap_state_t dummy_state = TAP_RESET;
 
static int dummy_clock;     /* edge detector */
 
static int clock_count;     /* count clocks in any stable state, only stable states */
 
static uint32_t dummy_data;
 
static bb_value_t dummy_read(void)
{
    int data = 1 & dummy_data;
    dummy_data = (dummy_data >> 1) | (1 << 31);
    return data ? BB_HIGH : BB_LOW;
}
 
static int dummy_write(int tck, int tms, int tdi)
{
    /* TAP standard: "state transitions occur on rising edge of clock" */
    if (tck != dummy_clock) {
        if (tck) {
            tap_state_t old_state = dummy_state;
            dummy_state = tap_state_transition(old_state, tms);
 
            if (old_state != dummy_state) {
                if (clock_count) {
                    LOG_DEBUG("dummy_tap: %d stable clocks", clock_count);
                    clock_count = 0;
                }
 
                LOG_DEBUG("dummy_tap: %s", tap_state_name(dummy_state));
 
#if defined(DEBUG)
                if (dummy_state == TAP_DRCAPTURE)
                    dummy_data = 0x01255043;
#endif
            } else {
                /* this is a stable state clock edge, no change of state here,
                 * simply increment clock_count for subsequent logging
                 */
                ++clock_count;
            }
        }
        dummy_clock = tck;
    }
    return ERROR_OK;
}
 
static int dummy_reset(int trst, int srst)
{
    dummy_clock = 0;
 
    if (trst || (srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
        dummy_state = TAP_RESET;
 
    LOG_DEBUG("reset to: %s", tap_state_name(dummy_state));
    return ERROR_OK;
}
 
static int dummy_led(bool on)
{
    return ERROR_OK;
}
 
static struct bitbang_interface dummy_bitbang = {
        .read = &dummy_read,
        .write = &dummy_write,
        .blink = &dummy_led,
    };
 
static int dummy_khz(int khz, int *jtag_speed)
{
    if (khz == 0)
        *jtag_speed = 0;
    else
        *jtag_speed = 64000/khz;
    return ERROR_OK;
}
 
static int dummy_speed_div(int speed, int *khz)
{
    if (speed == 0)
        *khz = 0;
    else
        *khz = 64000/speed;
 
    return ERROR_OK;
}
 
static int dummy_speed(int speed)
{
    return ERROR_OK;
}
 
static int dummy_init(void)
{
    bitbang_interface = &dummy_bitbang;
 
    return ERROR_OK;
}
 
static int dummy_quit(void)
{
    return ERROR_OK;
}
 
static const struct command_registration dummy_command_handlers[] = {
    {
        .name = "dummy",
        .mode = COMMAND_ANY,
        .help = "dummy interface driver commands",
        .chain = hello_command_handlers,
        .usage = "",
    },
    COMMAND_REGISTRATION_DONE,
};
 
/* The dummy driver is used to easily check the code path
 * where the target is unresponsive.
 */
static struct jtag_interface dummy_interface = {
    .supported = DEBUG_CAP_TMS_SEQ,
    .execute_queue = &bitbang_execute_queue,
};
 
struct adapter_driver dummy_adapter_driver = {
    .name = "dummy",
    .transports = jtag_only,
    .commands = dummy_command_handlers,
 
    .init = &dummy_init,
    .quit = &dummy_quit,
    .reset = &dummy_reset,
    .speed = &dummy_speed,
    .khz = &dummy_khz,
    .speed_div = &dummy_speed_div,
 
    .jtag_ops = &dummy_interface,
};