Support for driving RISC-V DM via Arty's own JTAG chain using BSCAN tunnel (#370)
Including adjustments in response to review comments.reverse-resume-order
Greg Savin
GitHub
parent
15f2d35bc6
commit
5190dd4cef
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@ -9502,6 +9502,11 @@ When utilizing version 0.11 of the RISC-V Debug Specification,
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and DBUS registers, respectively.
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@end deffn
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@deffn Command {riscv use_bscan_tunnel} value
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Enable or disable use of a BSCAN tunnel to reach DM. Supply the width of
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the DM transport TAP's instruction register to enable. Supply a value of 0 to disable.
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@end deffn
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@subsection RISC-V Authentication Commands
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The following commands can be used to authenticate to a RISC-V system. Eg. a
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@ -406,6 +406,10 @@ static void dump_field(int idle, const struct scan_field *field)
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static void select_dmi(struct target *target)
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{
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if (bscan_tunnel_ir_width != 0) {
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select_dmi_via_bscan(target);
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return;
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}
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jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
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}
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@ -415,6 +419,9 @@ static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
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uint8_t in_value[4];
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uint8_t out_value[4];
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if (bscan_tunnel_ir_width != 0)
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return dtmcontrol_scan_via_bscan(target, out);
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buf_set_u32(out_value, 0, 32, out);
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jtag_add_ir_scan(target->tap, &select_dtmcontrol, TAP_IDLE);
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@ -469,6 +476,8 @@ static dmi_status_t dmi_scan(struct target *target, uint32_t *address_in,
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.out_value = out,
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.in_value = in
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};
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uint8_t tunneled_dr_width;
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struct scan_field tunneled_dr[4];
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if (r->reset_delays_wait >= 0) {
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r->reset_delays_wait--;
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@ -486,8 +495,44 @@ static dmi_status_t dmi_scan(struct target *target, uint32_t *address_in,
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buf_set_u32(out, DTM_DMI_DATA_OFFSET, DTM_DMI_DATA_LENGTH, data_out);
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buf_set_u32(out, DTM_DMI_ADDRESS_OFFSET, info->abits, address_out);
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/* Assume dbus is already selected. */
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jtag_add_dr_scan(target->tap, 1, &field, TAP_IDLE);
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/* I wanted to place this code in a different function, but the way JTAG command
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queueing works in the jtag handling functions, the scan fields either have to be
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heap allocated, global/static, or else they need to stay on the stack until
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the jtag_execute_queue() call. Heap or static fields in this case doesn't seem
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the best fit. Declaring stack based field values in a subsidiary function call wouldn't
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work. */
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if (bscan_tunnel_ir_width != 0) {
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jtag_add_ir_scan(target->tap, &select_user4, TAP_IDLE);
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/* I wanted to use struct initialization syntax, but that would involve either
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declaring the variable within this scope (which would go out of scope at runtime
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before the JTAG queue gets executed, which is an error waiting to happen), or
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initializing outside of the check for whether a BSCAN tunnel was active (which
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would be a waste of CPU time when BSCAN tunnel is not being used. So I declared the
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struct at the function's top-level, so its lifetime exceeds the point at which
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the queue is executed, and initializing with assignments here. */
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memset(tunneled_dr, 0, sizeof(tunneled_dr));
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tunneled_dr[0].num_bits = 1;
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tunneled_dr[0].out_value = bscan_one;
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tunneled_dr[1].num_bits = 7;
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tunneled_dr_width = num_bits;
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tunneled_dr[1].out_value = &tunneled_dr_width;
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/* for BSCAN tunnel, there is a one-TCK skew between shift in and shift out, so
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scanning num_bits + 1, and then will right shift the input field after executing the queues */
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tunneled_dr[2].num_bits = num_bits+1;
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tunneled_dr[2].out_value = out;
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tunneled_dr[2].in_value = in;
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tunneled_dr[3].num_bits = 3;
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tunneled_dr[3].out_value = bscan_zero;
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jtag_add_dr_scan(target->tap, DIM(tunneled_dr), tunneled_dr, TAP_IDLE);
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} else {
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/* Assume dbus is already selected. */
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jtag_add_dr_scan(target->tap, 1, &field, TAP_IDLE);
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}
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int idle_count = info->dmi_busy_delay;
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if (exec)
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@ -502,6 +547,11 @@ static dmi_status_t dmi_scan(struct target *target, uint32_t *address_in,
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return DMI_STATUS_FAILED;
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}
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if (bscan_tunnel_ir_width != 0) {
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/* need to right-shift "in" by one bit, because of clock skew between BSCAN TAP and DM TAP */
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buffer_shr(in, num_bytes, 1);
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}
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if (data_in)
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*data_in = buf_get_u32(in, DTM_DMI_DATA_OFFSET, DTM_DMI_DATA_LENGTH);
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@ -170,6 +170,44 @@ struct scan_field select_idcode = {
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.out_value = ir_idcode
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};
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int bscan_tunnel_ir_width; /* if zero, then tunneling is not present/active */
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uint8_t bscan_zero[4] = {0};
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uint8_t bscan_one[4] = {1};
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uint8_t ir_user4[4] = {0x23};
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struct scan_field select_user4 = {
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.in_value = NULL,
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.out_value = ir_user4
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};
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uint8_t bscan_tunneled_ir_width[4] = {5}; /* overridden by assignment in riscv_init_target */
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struct scan_field _bscan_tunneled_select_dmi[] = {
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{
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.num_bits = 1,
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.out_value = bscan_zero,
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.in_value = NULL,
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},
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{
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.num_bits = 7,
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.out_value = bscan_tunneled_ir_width,
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.in_value = NULL,
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},
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{
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.num_bits = 0, /* initialized in riscv_init_target to ir width of DM */
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.out_value = ir_dbus,
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.in_value = NULL,
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},
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{
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.num_bits = 3,
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.out_value = bscan_zero,
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.in_value = NULL,
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}
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};
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struct scan_field *bscan_tunneled_select_dmi = _bscan_tunneled_select_dmi;
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uint32_t bscan_tunneled_select_dmi_num_fields = DIM(_bscan_tunneled_select_dmi);
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struct trigger {
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uint64_t address;
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uint32_t length;
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@ -201,12 +239,101 @@ range_t *expose_custom;
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static int riscv_resume_go_all_harts(struct target *target);
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void select_dmi_via_bscan(struct target *target)
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{
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jtag_add_ir_scan(target->tap, &select_user4, TAP_IDLE);
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jtag_add_dr_scan(target->tap, bscan_tunneled_select_dmi_num_fields, bscan_tunneled_select_dmi, TAP_IDLE);
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}
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uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out)
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{
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/* On BSCAN TAP: Select IR=USER4, issue tunneled IR scan via BSCAN TAP's DR */
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uint8_t tunneled_ir_width[4] = {bscan_tunnel_ir_width};
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uint8_t tunneled_dr_width[4] = {32};
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uint8_t out_value[5] = {0};
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uint8_t in_value[5] = {0};
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buf_set_u32(out_value, 0, 32, out);
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struct scan_field tunneled_ir[] = {
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{
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.num_bits = 1,
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.out_value = bscan_zero,
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.in_value = NULL,
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},
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{
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.num_bits = 7,
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.out_value = tunneled_ir_width,
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.in_value = NULL,
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},
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{
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.num_bits = bscan_tunnel_ir_width,
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.out_value = ir_dtmcontrol,
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.in_value = NULL,
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},
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{
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.num_bits = 3,
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.out_value = bscan_zero,
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.in_value = NULL,
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}
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};
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struct scan_field tunneled_dr[] = {
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{
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.num_bits = 1,
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.out_value = bscan_one,
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.in_value = NULL,
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},
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{
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.num_bits = 7,
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.out_value = tunneled_dr_width,
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.in_value = NULL,
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},
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/* for BSCAN tunnel, there is a one-TCK skew between shift in and shift out,
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so scanning 33 bits and then right shifting the in_value after the scan is completed */
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{
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.num_bits = 32+1,
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.out_value = out_value,
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.in_value = in_value,
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},
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{
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.num_bits = 3,
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.out_value = bscan_zero,
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.in_value = NULL,
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}
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};
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jtag_add_ir_scan(target->tap, &select_user4, TAP_IDLE);
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jtag_add_dr_scan(target->tap, DIM(tunneled_ir), tunneled_ir, TAP_IDLE);
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jtag_add_dr_scan(target->tap, DIM(tunneled_dr), tunneled_dr, TAP_IDLE);
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select_dmi_via_bscan(target);
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int retval = jtag_execute_queue();
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if (retval != ERROR_OK) {
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LOG_ERROR("failed jtag scan: %d", retval);
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return retval;
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}
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/* Note the starting offset is bit 1, not bit 0. In BSCAN tunnel, there is a one-bit TCK skew between
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output and input */
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uint32_t in = buf_get_u32(in_value, 1, 32);
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LOG_DEBUG("DTMCS: 0x%x -> 0x%x", out, in);
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return in;
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}
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static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
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{
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struct scan_field field;
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uint8_t in_value[4];
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uint8_t out_value[4];
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if (bscan_tunnel_ir_width != 0)
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return dtmcontrol_scan_via_bscan(target, out);
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buf_set_u32(out_value, 0, 32, out);
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jtag_add_ir_scan(target->tap, &select_dtmcontrol, TAP_IDLE);
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@ -266,6 +393,12 @@ static int riscv_init_target(struct command_context *cmd_ctx,
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select_dbus.num_bits = target->tap->ir_length;
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select_idcode.num_bits = target->tap->ir_length;
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if (bscan_tunnel_ir_width != 0) {
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select_user4.num_bits = target->tap->ir_length;
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bscan_tunneled_ir_width[0] = bscan_tunnel_ir_width;
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bscan_tunneled_select_dmi[2].num_bits = bscan_tunnel_ir_width;
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}
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riscv_semihosting_init(target);
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target->debug_reason = DBG_REASON_DBGRQ;
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@ -1827,6 +1960,23 @@ COMMAND_HANDLER(riscv_set_ir)
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}
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}
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COMMAND_HANDLER(riscv_use_bscan_tunnel)
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{
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int irwidth = 0;
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if (CMD_ARGC > 1) {
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LOG_ERROR("Command takes at most one argument");
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return ERROR_COMMAND_SYNTAX_ERROR;
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}
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if (CMD_ARGC == 1)
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COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], irwidth);
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bscan_tunnel_ir_width = irwidth;
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return ERROR_OK;
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}
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static const struct command_registration riscv_exec_command_handlers[] = {
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{
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.name = "test_compliance",
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@ -1933,6 +2083,15 @@ static const struct command_registration riscv_exec_command_handlers[] = {
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.usage = "riscv set_ir_idcode [idcode|dtmcs|dmi] value",
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.help = "Set IR value for specified JTAG register."
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},
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{
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.name = "use_bscan_tunnel",
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.handler = riscv_use_bscan_tunnel,
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.mode = COMMAND_ANY,
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.usage = "riscv use_bscan_tunnel value",
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.help = "Enable or disable use of a BSCAN tunnel to reach DM. Supply "
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"the width of the DM transport TAP's instruction register to "
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"enable. Supply a value of 0 to disable."
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},
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COMMAND_REGISTRATION_DONE
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};
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@ -166,6 +166,16 @@ extern struct scan_field select_dbus;
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extern uint8_t ir_idcode[4];
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extern struct scan_field select_idcode;
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extern struct scan_field select_user4;
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extern struct scan_field *bscan_tunneled_select_dmi;
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extern uint32_t bscan_tunneled_select_dmi_num_fields;
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extern uint8_t bscan_zero[4];
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extern uint8_t bscan_one[4];
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extern int bscan_tunnel_ir_width;
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uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out);
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void select_dmi_via_bscan(struct target *target);
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/*** OpenOCD Interface */
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int riscv_openocd_poll(struct target *target);
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@ -0,0 +1,10 @@
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#
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# Be sure you include the speed and interface before this file
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# Example:
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# -c "adapter_khz 5000" -f "interface/ftdi/arty-onboard-ftdi.cfg" -f "board/sifive-e31arty-onboard-ftdi.cfg"
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set _CHIPNAME arty
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jtag newtap $_CHIPNAME bs -irlen 6 -expected-id 0x0362d093
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echo "Ready for Remote Connections"
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@ -0,0 +1,25 @@
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#
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# Be sure you include the speed and interface before this file
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# Example:
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# -c "adapter_khz 5000" -f "interface/ftdi/arty-onboard-ftdi.cfg" -f "board/sifive-e31arty-onboard-ftdi.cfg"
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set _CHIPNAME riscv
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jtag newtap $_CHIPNAME cpu -irlen 6; # -expected-id 0x0362d093
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set _TARGETNAME $_CHIPNAME.cpu
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target create $_TARGETNAME.0 riscv -chain-position $_TARGETNAME
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$_TARGETNAME.0 configure -work-area-phys 0x80000000 -work-area-size 10000 -work-area-backup 1
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riscv use_bscan_tunnel 5
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# Uncomment if hardware has flash
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# flash bank spi0 fespi 0x40000000 0 0 0 $_TARGETNAME.0 0x20004000
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init
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if {[ info exists pulse_srst]} {
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ftdi_set_signal nSRST 0
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ftdi_set_signal nSRST z
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}
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halt
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# Uncomment if hardware has flash
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# flash protect 0 64 last off
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echo "Ready for Remote Connections"
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@ -0,0 +1,7 @@
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interface ftdi
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# ftdi_device_desc "Arty On-board FTDI interface"
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ftdi_vid_pid 0x0403 0x6010
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ftdi_channel 0
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ftdi_layout_init 0x0088 0x008b
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reset_config none
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