Checking in for backup.

configure.ac

@@ -111,6 +111,7 @@ m4_define([ADAPTER_OPT], [m4_translit(ADAPTER_ARG($1), [_], [-])])
 m4_define([USB1_ADAPTERS],
 	[[[ftdi], [MPSSE mode of FTDI based devices], [FTDI]],
 	[[ftdi_oscan1], [cJTAG OSCAN1 tunneled thru MPSSE], [FTDI_OSCAN1]],
+	[[riscv_arty_bscan], [Access to RISCV on Arty board via BSCAN], [RISCV_ARTY_BSCAN]],
 	[[stlink], [ST-Link JTAG Programmer], [HLADAPTER_STLINK]],
 	[[ti_icdi], [TI ICDI JTAG Programmer], [HLADAPTER_ICDI]],
 	[[ulink], [Keil ULINK JTAG Programmer], [ULINK]],

src/target/riscv/riscv-013.c

@@ -404,8 +404,108 @@ static void dump_field(int idle, const struct scan_field *field)
 
 /*** Utility functions. ***/
 
+#if BUILD_RISCV_ARTY_BSCAN == 1
+static 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);
+}
+
+static uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out)
+{
+	/* jtag_add_ir_scan(target->tap, &select_dtmcontrol, TAP_IDLE);	*/
+
+	/* On BSCAN TAP: Select IR=USER4, issue tunneled IR scan via BSCAN TAP's DR */
+
+	uint8_t zero[4] = {0};
+	uint8_t one[4] = {1};
+	uint8_t tunneled_ir_width[4] = {target->bscan_tunnel_ir_width};
+	uint8_t tunneled_dr_width[4] = {32};
+	uint8_t out_0[4] = {out & 0x1};
+	uint8_t out_31_1[4];
+	uint8_t in_value[4];
+
+	buf_set_u32(out_31_1, 0, 32, (out >> 1));
+	
+	struct scan_field tunneled_ir[] = {
+		{
+			.num_bits = 1,
+			.out_value = zero,
+			.in_value = NULL,
+		},
+		{
+			.num_bits = 7,
+			.out_value = tunneled_ir_width,
+			.in_value = NULL,
+		},
+		{
+			.num_bits = target->bscan_tunnel_ir_width,
+			.out_value = ir_dtmcontrol,
+			.in_value = NULL,
+		},
+		{
+			.num_bits = 3,
+			.out_value = zero,
+			.in_value = NULL,
+		}
+		
+	};
+	struct scan_field tunneled_dr[] = {
+		{
+			.num_bits = 1,
+			.out_value = 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 splitting the DR payload into 2 fields */
+		{
+			.num_bits = 1,
+			.out_value = out_0,
+			.in_value = NULL,
+		},
+		{
+			.num_bits = 32,
+			.out_value = out_31_1,
+			.in_value = in_value,
+		},
+		{
+			.num_bits = 3,
+			.out_value = zero,
+			.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);
+	select_dmi_via_bscan(target);
+
+	int retval = jtag_execute_queue();
+	if (retval != ERROR_OK) {
+		LOG_ERROR("failed jtag scan: %d", retval);
+		return retval;
+	}
+
+	uint32_t in = buf_get_u32(in_value, 0, 32);
+	LOG_DEBUG("DTMCS: 0x%x -> 0x%x", out, in);
+
+	return in;
+}
+
+#endif
+
 static void select_dmi(struct target *target)
 {
+#if BUILD_RISCV_ARTY_BSCAN == 1
+	if (target->bscan_tunnel_ir_width != 0) {
+		select_dmi_via_bscan(target);
+		return;
+	}
+#endif	
 	jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 }
 
@@ -415,6 +515,12 @@ static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
 	uint8_t in_value[4];
 	uint8_t out_value[4];
 
+#if BUILD_RISCV_ARTY_BSCAN == 1
+	if (target->bscan_tunnel_ir_width != 0) {
+		return dtmcontrol_scan_via_bscan(target, out);
+	}
+#endif	
+
 	buf_set_u32(out_value, 0, 32, out);
 
 	jtag_add_ir_scan(target->tap, &select_dtmcontrol, TAP_IDLE);

src/target/riscv/riscv.c

@@ -170,6 +170,44 @@ struct scan_field select_idcode = {
 	.out_value = ir_idcode
 };
 
+#if BUILD_RISCV_ARTY_BSCAN == 1
+
+uint8_t ir_user4[4] = {0x23};
+struct scan_field select_user4 = {
+	.in_value = NULL,
+	.out_value = ir_user4
+};
+
+
+uint8_t zero[4] = {0};
+uint8_t one[4] = {1};
+uint8_t tunneled_ir_width[4] = {5};  /* overridden by assignment in riscv_init_target */
+struct scan_field _bscan_tunneled_select_dmi[] = {
+		{
+			.num_bits = 1,
+			.out_value = zero,
+			.in_value = NULL,
+		},
+		{
+			.num_bits = 7,
+			.out_value = tunneled_ir_width,
+			.in_value = NULL,
+		},
+		{
+			.num_bits = 0, /* initialized in riscv_init_target to ir width of DM */
+			.out_value = ir_dbus,
+			.in_value = NULL,
+		},
+		{
+			.num_bits = 3,
+			.out_value = zero,
+			.in_value = NULL,
+		}
+};
+struct scan_field *bscan_tunneled_select_dmi = _bscan_tunneled_select_dmi;
+uint32_t bscan_tunneled_select_dmi_num_fields = sizeof(bscan_tunneled_select_dmi)/sizeof(bscan_tunneled_select_dmi[0]);
+#endif
+
 struct trigger {
 	uint64_t address;
 	uint32_t length;
@@ -266,6 +304,15 @@ static int riscv_init_target(struct command_context *cmd_ctx,
 	select_dbus.num_bits = target->tap->ir_length;
 	select_idcode.num_bits = target->tap->ir_length;
 
+#if BUILD_RISCV_ARTY_BSCAN == 1
+	if (target->bscan_tunnel_ir_width != 0) {
+		select_user4.num_bits = target->bscan_tunnel_ir_width;		
+		tunneled_ir_width[0] = target->bscan_tunnel_ir_width;
+		bscan_tunneled_select_dmi[2].num_bits = target->bscan_tunnel_ir_width;
+	}
+	
+#endif	
+
 	riscv_semihosting_init(target);
 
 	target->debug_reason = DBG_REASON_DBGRQ;

src/target/riscv/riscv.h

@@ -165,6 +165,11 @@ extern uint8_t ir_dbus[4];
 extern struct scan_field select_dbus;
 extern uint8_t ir_idcode[4];
 extern struct scan_field select_idcode;
+#if BUILD_RISCV_ARTY_BSCAN == 1
+extern struct scan_field select_user4;
+extern struct scan_field *bscan_tunneled_select_dmi;
+extern uint32_t bscan_tunneled_select_dmi_num_fields;
+#endif
 
 /*** OpenOCD Interface */
 int riscv_openocd_poll(struct target *target);

src/target/target.c

@@ -4603,6 +4603,7 @@ enum target_cfg_param {
 	TCFG_RTOS,
 	TCFG_DEFER_EXAMINE,
 	TCFG_GDB_PORT,
+	TCFG_BSCAN_TUNNEL_IR_WIDTH,	
 };
 
 static Jim_Nvp nvp_config_opts[] = {
@@ -4619,6 +4620,9 @@ static Jim_Nvp nvp_config_opts[] = {
 	{ .name = "-rtos",             .value = TCFG_RTOS },
 	{ .name = "-defer-examine",    .value = TCFG_DEFER_EXAMINE },
 	{ .name = "-gdb-port",         .value = TCFG_GDB_PORT },
+#if BUILD_RISCV_ARTY_BSCAN == 1
+	{ .name = "-bscan-tunnel-ir-width",     .value = TCFG_BSCAN_TUNNEL_IR_WIDTH },	
+#endif	
 	{ .name = NULL, .value = -1 }
 };
 
@@ -4920,6 +4924,20 @@ no_params:
 			Jim_SetResultString(goi->interp, target->gdb_port_override ? : "undefined", -1);
 			/* loop for more */
 			break;
+			
+		case TCFG_BSCAN_TUNNEL_IR_WIDTH:
+			if (goi->isconfigure) {
+				e = Jim_GetOpt_Wide(goi, &w);
+				if (e != JIM_OK)
+					return e;
+				target->bscan_tunnel_ir_width = (int32_t)w;
+			} else {
+				if (goi->argc != 0)
+					goto no_params;
+			}
+			Jim_SetResult(goi->interp, Jim_NewIntObj(goi->interp, target->bscan_tunnel_ir_width));
+			/* loop for more */
+			break;
 		}
 	} /* while (goi->argc) */
 

src/target/target.h

@@ -210,6 +210,9 @@ struct target {
 
 	/* The semihosting information, extracted from the target. */
 	struct semihosting *semihosting;
+#if BUILD_RISCV_ARTY_BSCAN == 1	
+	int bscan_tunnel_ir_width;  /* if zero, then tunneling is not present/active */
+#endif	
 };
 
 struct target_list {