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Inverted Frame to Pseudo Tap for Simpler Hardware to Decode DR (#373) 

* Inverted Frame to Pseudo Tap for Simpler Hardware to Decode

Given the variable supported message length , a prefix  decoding approach is significantly simpler for a pseudo tap architecture with a shift reg of len =  max len of packet. This prefix coding packet also makes the message len field redundant , as that is implict in ir_len and the ir selected.

* style patch

* non-conflict with original

* style patch

* style patch

* requested changes

* style-patch
reverse-resume-order
Paul George 2019-06-11 02:03:50 +05:30 committed by Tim Newsome
parent 998fed1fe7
commit fd9c54b1fe
3 changed files with 145 additions and 77 deletions
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43
src/target/riscv/riscv-013.c
View File

@ -516,22 +516,37 @@ static dmi_status_t dmi_scan(struct target *target, uint32_t *address_in,
struct at the function's top-level, so its lifetime exceeds the point at which
the queue is executed, and initializing with assignments here. */
memset(tunneled_dr, 0, sizeof(tunneled_dr));
tunneled_dr[0].num_bits = 1;
tunneled_dr[0].out_value = bscan_one;
if (bscan_tunnel_type == BSCAN_TUNNEL_DATA_REGISTER) {
tunneled_dr[3].num_bits = 1;
tunneled_dr[3].out_value = bscan_one;
tunneled_dr[2].num_bits = 7;
tunneled_dr_width = num_bits;
tunneled_dr[2].out_value = &tunneled_dr_width;
/* for BSCAN tunnel, there is a one-TCK skew between shift in and shift out, so
scanning num_bits + 1, and then will right shift the input field after executing the queues */
tunneled_dr[1].num_bits = 7;
tunneled_dr_width = num_bits;
tunneled_dr[1].out_value = &tunneled_dr_width;
tunneled_dr[1].num_bits = num_bits+1;
tunneled_dr[1].out_value = out;
tunneled_dr[1].in_value = in;
/* for BSCAN tunnel, there is a one-TCK skew between shift in and shift out, so
scanning num_bits + 1, and then will right shift the input field after executing the queues */
tunneled_dr[2].num_bits = num_bits+1;
tunneled_dr[2].out_value = out;
tunneled_dr[2].in_value = in;
tunneled_dr[3].num_bits = 3;
tunneled_dr[3].out_value = bscan_zero;
tunneled_dr[0].num_bits = 3;
tunneled_dr[0].out_value = bscan_zero;
} else {
/* BSCAN_TUNNEL_NESTED_TAP */
tunneled_dr[0].num_bits = 1;
tunneled_dr[0].out_value = bscan_one;
tunneled_dr[1].num_bits = 7;
tunneled_dr_width = num_bits;
tunneled_dr[1].out_value = &tunneled_dr_width;
/* for BSCAN tunnel, there is a one-TCK skew between shift in and shift out, so
scanning num_bits + 1, and then will right shift the input field after executing the queues */
tunneled_dr[2].num_bits = num_bits+1;
tunneled_dr[2].out_value = out;
tunneled_dr[2].in_value = in;
tunneled_dr[3].num_bits = 3;
tunneled_dr[3].out_value = bscan_zero;
}
jtag_add_dr_scan(target->tap, DIM(tunneled_dr), tunneled_dr, TAP_IDLE);
} else {
/* Assume dbus is already selected. */
@ -561,9 +576,7 @@ static dmi_status_t dmi_scan(struct target *target, uint32_t *address_in,
if (address_in)
*address_in = buf_get_u32(in, DTM_DMI_ADDRESS_OFFSET, info->abits);
dump_field(idle_count, &field);
return buf_get_u32(in, DTM_DMI_OP_OFFSET, DTM_DMI_OP_LENGTH);
}

177
src/target/riscv/riscv.c
View File

@ -170,8 +170,9 @@ struct scan_field select_idcode = {
.out_value = ir_idcode
};
bscan_tunnel_type_t bscan_tunnel_type;
int bscan_tunnel_ir_width; /* if zero, then tunneling is not present/active */
uint8_t bscan_zero[4] = {0};
uint8_t bscan_one[4] = {1};
@ -183,7 +184,30 @@ struct scan_field select_user4 = {
uint8_t bscan_tunneled_ir_width[4] = {5}; /* overridden by assignment in riscv_init_target */
struct scan_field _bscan_tunneled_select_dmi[] = {
struct scan_field _bscan_tunnel_data_register_select_dmi[] = {
{
.num_bits = 3,
.out_value = bscan_zero,
.in_value = NULL,
},
{
.num_bits = 5, /* initialized in riscv_init_target to ir width of DM */
.out_value = ir_dbus,
.in_value = NULL,
},
{
.num_bits = 7,
.out_value = bscan_tunneled_ir_width,
.in_value = NULL,
},
{
.num_bits = 1,
.out_value = bscan_zero,
.in_value = NULL,
}
};
struct scan_field _bscan_tunnel_nested_tap_select_dmi[] = {
{
.num_bits = 1,
.out_value = bscan_zero,
@ -205,8 +229,11 @@ struct scan_field _bscan_tunneled_select_dmi[] = {
.in_value = NULL,
}
};
struct scan_field *bscan_tunneled_select_dmi = _bscan_tunneled_select_dmi;
uint32_t bscan_tunneled_select_dmi_num_fields = DIM(_bscan_tunneled_select_dmi);
struct scan_field *bscan_tunnel_nested_tap_select_dmi = _bscan_tunnel_nested_tap_select_dmi;
uint32_t bscan_tunnel_nested_tap_select_dmi_num_fields = DIM(_bscan_tunnel_nested_tap_select_dmi);
struct scan_field *bscan_tunnel_data_register_select_dmi = _bscan_tunnel_data_register_select_dmi;
uint32_t bscan_tunnel_data_register_select_dmi_num_fields = DIM(_bscan_tunnel_data_register_select_dmi);
struct trigger {
uint64_t address;
@ -242,10 +269,14 @@ static int riscv_resume_go_all_harts(struct target *target);
void select_dmi_via_bscan(struct target *target)
{
jtag_add_ir_scan(target->tap, &select_user4, TAP_IDLE);
jtag_add_dr_scan(target->tap, bscan_tunneled_select_dmi_num_fields, bscan_tunneled_select_dmi, TAP_IDLE);
if (bscan_tunnel_type == BSCAN_TUNNEL_DATA_REGISTER)
jtag_add_dr_scan(target->tap, bscan_tunnel_data_register_select_dmi_num_fields,
bscan_tunnel_data_register_select_dmi, TAP_IDLE);
else /* BSCAN_TUNNEL_NESTED_TAP */
jtag_add_dr_scan(target->tap, bscan_tunnel_nested_tap_select_dmi_num_fields,
bscan_tunnel_nested_tap_select_dmi, TAP_IDLE);
}
uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out)
{
/* On BSCAN TAP: Select IR=USER4, issue tunneled IR scan via BSCAN TAP's DR */
@ -255,54 +286,63 @@ uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out)
uint8_t in_value[5] = {0};
buf_set_u32(out_value, 0, 32, out);
struct scan_field tunneled_ir[4] = {};
struct scan_field tunneled_dr[4] = {};
struct scan_field tunneled_ir[] = {
{
.num_bits = 1,
.out_value = bscan_zero,
.in_value = NULL,
},
{
.num_bits = 7,
.out_value = tunneled_ir_width,
.in_value = NULL,
},
{
.num_bits = bscan_tunnel_ir_width,
.out_value = ir_dtmcontrol,
.in_value = NULL,
},
{
.num_bits = 3,
.out_value = bscan_zero,
.in_value = NULL,
}
};
struct scan_field tunneled_dr[] = {
{
.num_bits = 1,
.out_value = bscan_one,
.in_value = NULL,
},
{
.num_bits = 7,
.out_value = tunneled_dr_width,
.in_value = NULL,
},
/* for BSCAN tunnel, there is a one-TCK skew between shift in and shift out,
so scanning 33 bits and then right shifting the in_value after the scan is completed */
{
.num_bits = 32+1,
.out_value = out_value,
.in_value = in_value,
},
{
.num_bits = 3,
.out_value = bscan_zero,
.in_value = NULL,
}
};
if (bscan_tunnel_type == BSCAN_TUNNEL_DATA_REGISTER) {
tunneled_ir[0].num_bits = 3;
tunneled_ir[0].out_value = bscan_zero;
tunneled_ir[0].in_value = NULL;
tunneled_ir[1].num_bits = bscan_tunnel_ir_width;
tunneled_ir[1].out_value = ir_dtmcontrol;
tunneled_ir[1].in_value = NULL;
tunneled_ir[2].num_bits = 7;
tunneled_ir[2].out_value = tunneled_ir_width;
tunneled_ir[2].in_value = NULL;
tunneled_ir[3].num_bits = 1;
tunneled_ir[3].out_value = bscan_zero;
tunneled_ir[3].in_value = NULL;
tunneled_dr[0].num_bits = 3;
tunneled_dr[0].out_value = bscan_zero;
tunneled_dr[0].in_value = NULL;
tunneled_dr[1].num_bits = 32+1;
tunneled_dr[1].out_value = out_value;
tunneled_dr[1].in_value = in_value;
tunneled_dr[2].num_bits = 7;
tunneled_dr[2].out_value = tunneled_dr_width;
tunneled_dr[2].in_value = NULL;
tunneled_dr[3].num_bits = 1;
tunneled_dr[3].out_value = bscan_one;
tunneled_dr[3].in_value = NULL;
} else{
/* BSCAN_TUNNEL_NESTED_TAP */
tunneled_ir[3].num_bits = 3;
tunneled_ir[3].out_value = bscan_zero;
tunneled_ir[3].in_value = NULL;
tunneled_ir[2].num_bits = bscan_tunnel_ir_width;
tunneled_ir[2].out_value = ir_dtmcontrol;
tunneled_ir[1].in_value = NULL;
tunneled_ir[1].num_bits = 7;
tunneled_ir[1].out_value = tunneled_ir_width;
tunneled_ir[2].in_value = NULL;
tunneled_ir[0].num_bits = 1;
tunneled_ir[0].out_value = bscan_zero;
tunneled_ir[0].in_value = NULL;
tunneled_dr[3].num_bits = 3;
tunneled_dr[3].out_value = bscan_zero;
tunneled_dr[3].in_value = NULL;
tunneled_dr[2].num_bits = 32+1;
tunneled_dr[2].out_value = out_value;
tunneled_dr[2].in_value = in_value;
tunneled_dr[1].num_bits = 7;
tunneled_dr[1].out_value = tunneled_dr_width;
tunneled_dr[1].in_value = NULL;
tunneled_dr[0].num_bits = 1;
tunneled_dr[0].out_value = bscan_one;
tunneled_dr[0].in_value = NULL;
}
jtag_add_ir_scan(target->tap, &select_user4, TAP_IDLE);
jtag_add_dr_scan(target->tap, DIM(tunneled_ir), tunneled_ir, TAP_IDLE);
jtag_add_dr_scan(target->tap, DIM(tunneled_dr), tunneled_dr, TAP_IDLE);
@ -313,7 +353,6 @@ uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out)
LOG_ERROR("failed jtag scan: %d", retval);
return retval;
}
/* Note the starting offset is bit 1, not bit 0. In BSCAN tunnel, there is a one-bit TCK skew between
output and input */
uint32_t in = buf_get_u32(in_value, 1, 32);
@ -396,7 +435,10 @@ static int riscv_init_target(struct command_context *cmd_ctx,
if (bscan_tunnel_ir_width != 0) {
select_user4.num_bits = target->tap->ir_length;
bscan_tunneled_ir_width[0] = bscan_tunnel_ir_width;
bscan_tunneled_select_dmi[2].num_bits = bscan_tunnel_ir_width;
if (bscan_tunnel_type == BSCAN_TUNNEL_DATA_REGISTER)
bscan_tunnel_data_register_select_dmi[1].num_bits = bscan_tunnel_ir_width;
else /* BSCAN_TUNNEL_NESTED_TAP */
bscan_tunnel_nested_tap_select_dmi[2].num_bits = bscan_tunnel_ir_width;
}
riscv_semihosting_init(target);
@ -2023,20 +2065,29 @@ COMMAND_HANDLER(riscv_set_ir)
COMMAND_HANDLER(riscv_use_bscan_tunnel)
{
int irwidth = 0;
int tunnel_type = BSCAN_TUNNEL_NESTED_TAP;
if (CMD_ARGC > 1) {
LOG_ERROR("Command takes at most one argument");
if (CMD_ARGC > 2) {
LOG_ERROR("Command takes at most two arguments");
return ERROR_COMMAND_SYNTAX_ERROR;
}
if (CMD_ARGC == 1)
} else if (CMD_ARGC == 1) {
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], irwidth);
} else if (CMD_ARGC == 2) {
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], irwidth);
COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], tunnel_type);
}
if (tunnel_type == BSCAN_TUNNEL_NESTED_TAP)
LOG_INFO("Nested Tap based Bscan Tunnel Selected");
else if (tunnel_type == BSCAN_TUNNEL_DATA_REGISTER)
LOG_INFO("Simple Register based Bscan Tunnel Selected");
else
LOG_INFO("Invalid Tunnel type selected ! : selecting default Nested Tap Type");
bscan_tunnel_type = tunnel_type;
bscan_tunnel_ir_width = irwidth;
return ERROR_OK;
}
static const struct command_registration riscv_exec_command_handlers[] = {
{
.name = "test_compliance",
@ -2147,10 +2198,12 @@ static const struct command_registration riscv_exec_command_handlers[] = {
.name = "use_bscan_tunnel",
.handler = riscv_use_bscan_tunnel,
.mode = COMMAND_ANY,
.usage = "riscv use_bscan_tunnel value",
.usage = "riscv use_bscan_tunnel value [type]",
.help = "Enable or disable use of a BSCAN tunnel to reach DM. Supply "
"the width of the DM transport TAP's instruction register to "
"enable. Supply a value of 0 to disable."
"enable. Supply a value of 0 to disable. Pass A second argument "
"(optional) to indicate Bscan Tunnel Type {0:(default) NESTED_TAP , "
"1: DATA_REGISTER}"
},
COMMAND_REGISTRATION_DONE
};

2
src/target/riscv/riscv.h
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@ -174,7 +174,9 @@ extern struct scan_field *bscan_tunneled_select_dmi;
extern uint32_t bscan_tunneled_select_dmi_num_fields;
extern uint8_t bscan_zero[4];
extern uint8_t bscan_one[4];
typedef enum { BSCAN_TUNNEL_NESTED_TAP, BSCAN_TUNNEL_DATA_REGISTER } bscan_tunnel_type_t;
extern int bscan_tunnel_ir_width;
extern bscan_tunnel_type_t bscan_tunnel_type;
uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out);
void select_dmi_via_bscan(struct target *target);