do not assume DTM version unless dtmcontrol is read successfully

Change-Id: I5f2003b7ac5ce87af6ca9a4fcb46140682a8cfdf
Signed-off-by: Parshintsev Anatoly <anatoly.parshintsev@syntacore.com>

4 files changed, 88 insertions, 38 deletions

diff --git a/src/target/riscv/riscv-011.c b/src/target/riscv/riscv-011.c
index fb94983..dd7676e 100644
--- a/src/target/riscv/riscv-011.c
+++ b/src/target/riscv/riscv-011.c
@@ -273,7 +273,7 @@ static uint16_t dram_address(unsigned int index)
 		return 0x40 + index - 0x10;
 }
 
-static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
+static int dtmcontrol_scan(struct target *target, uint32_t out, uint32_t *in_ptr)
 {
 	struct scan_field field;
 	uint8_t in_value[4];
@@ -300,7 +300,9 @@ static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
 	uint32_t in = buf_get_u32(field.in_value, 0, 32);
 	LOG_DEBUG("DTMCONTROL: 0x%x -> 0x%x", out, in);
 
-	return in;
+	if (in_ptr)
+		*in_ptr = in;
+	return ERROR_OK;
 }
 
 static uint32_t idcode_scan(struct target *target)
@@ -338,7 +340,7 @@ static void increase_dbus_busy_delay(struct target *target)
 			info->dtmcontrol_idle, info->dbus_busy_delay,
 			info->interrupt_high_delay);
 
-	dtmcontrol_scan(target, DTMCONTROL_DBUS_RESET);
+	dtmcontrol_scan(target, DTMCONTROL_DBUS_RESET, NULL /* discard value */);
 }
 
 static void increase_interrupt_high_delay(struct target *target)
@@ -1459,16 +1461,17 @@ static int step(struct target *target, int current, target_addr_t address,
 static int examine(struct target *target)
 {
 	/* Don't need to select dbus, since the first thing we do is read dtmcontrol. */
+	uint32_t dtmcontrol;
+	if (dtmcontrol_scan(target, 0, &dtmcontrol) != ERROR_OK || dtmcontrol == 0) {
+		LOG_ERROR("Could not scan dtmcontrol. Check JTAG connectivity/board power.");
+		return ERROR_FAIL;
+	}
 
-	uint32_t dtmcontrol = dtmcontrol_scan(target, 0);
 	LOG_DEBUG("dtmcontrol=0x%x", dtmcontrol);
 	LOG_DEBUG("  addrbits=%d", get_field(dtmcontrol, DTMCONTROL_ADDRBITS));
 	LOG_DEBUG("  version=%d", get_field(dtmcontrol, DTMCONTROL_VERSION));
 	LOG_DEBUG("  idle=%d", get_field(dtmcontrol, DTMCONTROL_IDLE));
-	if (dtmcontrol == 0) {
-		LOG_ERROR("dtmcontrol is 0. Check JTAG connectivity/board power.");
-		return ERROR_FAIL;
-	}
+
 	if (get_field(dtmcontrol, DTMCONTROL_VERSION) != 0) {
 		LOG_ERROR("Unsupported DTM version %d. (dtmcontrol=0x%x)",
 				get_field(dtmcontrol, DTMCONTROL_VERSION), dtmcontrol);
diff --git a/src/target/riscv/riscv-013.c b/src/target/riscv/riscv-013.c
index 7d3d950..01e1c6f 100644
--- a/src/target/riscv/riscv-013.c
+++ b/src/target/riscv/riscv-013.c
@@ -411,14 +411,14 @@ static void select_dmi(struct target *target)
 	jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 }
 
-static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
+static int dtmcontrol_scan(struct target *target, uint32_t out, uint32_t *in_ptr)
 {
 	struct scan_field field;
 	uint8_t in_value[4];
 	uint8_t out_value[4] = { 0 };
 
 	if (bscan_tunnel_ir_width != 0)
-		return dtmcontrol_scan_via_bscan(target, out);
+		return dtmcontrol_scan_via_bscan(target, out, in_ptr);
 
 	buf_set_u32(out_value, 0, 32, out);
 
@@ -441,7 +441,9 @@ static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
 	uint32_t in = buf_get_u32(field.in_value, 0, 32);
 	LOG_DEBUG("DTMCS: 0x%x -> 0x%x", out, in);
 
-	return in;
+	if (in_ptr)
+		*in_ptr = in;
+	return ERROR_OK;
 }
 
 static void increase_dmi_busy_delay(struct target *target)
@@ -452,7 +454,7 @@ static void increase_dmi_busy_delay(struct target *target)
 			info->dtmcs_idle, info->dmi_busy_delay,
 			info->ac_busy_delay);
 
-	dtmcontrol_scan(target, DTM_DTMCS_DMIRESET);
+	dtmcontrol_scan(target, DTM_DTMCS_DMIRESET, NULL /* discard result */);
 }
 
 /**
@@ -597,7 +599,7 @@ static int dmi_op_timeout(struct target *target, uint32_t *data_in,
 		} else if (status == DMI_STATUS_SUCCESS) {
 			break;
 		} else {
-			dtmcontrol_scan(target, DTM_DTMCS_DMIRESET);
+			dtmcontrol_scan(target, DTM_DTMCS_DMIRESET, NULL /* discard result */);
 			break;
 		}
 		if (time(NULL) - start > timeout_sec)
@@ -632,7 +634,7 @@ static int dmi_op_timeout(struct target *target, uint32_t *data_in,
 							"Failed DMI %s (NOP) at 0x%x; status=%d", op_name, address,
 							status);
 				}
-				dtmcontrol_scan(target, DTM_DTMCS_DMIRESET);
+				dtmcontrol_scan(target, DTM_DTMCS_DMIRESET, NULL /* discard result */);
 				return ERROR_FAIL;
 			}
 			if (time(NULL) - start > timeout_sec)
@@ -1845,17 +1847,19 @@ static int examine(struct target *target)
 	/* Don't need to select dbus, since the first thing we do is read dtmcontrol. */
 	LOG_TARGET_DEBUG(target, "dbgbase=0x%x", target->dbgbase);
 
-	uint32_t dtmcontrol = dtmcontrol_scan(target, 0);
+	uint32_t dtmcontrol;
+	if (dtmcontrol_scan(target, 0, &dtmcontrol) != ERROR_OK || dtmcontrol == 0) {
+		LOG_TARGET_ERROR(target, "Could not scan dtmcontrol. Check JTAG connectivity/board power.");
+		return ERROR_FAIL;
+	}
+
 	LOG_TARGET_DEBUG(target, "dtmcontrol=0x%x", dtmcontrol);
 	LOG_TARGET_DEBUG(target, "  dmireset=%d", get_field(dtmcontrol, DTM_DTMCS_DMIRESET));
 	LOG_TARGET_DEBUG(target, "  idle=%d", get_field(dtmcontrol, DTM_DTMCS_IDLE));
 	LOG_TARGET_DEBUG(target, "  dmistat=%d", get_field(dtmcontrol, DTM_DTMCS_DMISTAT));
 	LOG_TARGET_DEBUG(target, "  abits=%d", get_field(dtmcontrol, DTM_DTMCS_ABITS));
 	LOG_TARGET_DEBUG(target, "  version=%d", get_field(dtmcontrol, DTM_DTMCS_VERSION));
-	if (dtmcontrol == 0) {
-		LOG_TARGET_ERROR(target, "dtmcontrol is 0. Check JTAG connectivity/board power.");
-		return ERROR_FAIL;
-	}
+
 	if (get_field(dtmcontrol, DTM_DTMCS_VERSION) != 1) {
 		LOG_TARGET_ERROR(target, "Unsupported DTM version %d. (dtmcontrol=0x%x)",
 				get_field(dtmcontrol, DTM_DTMCS_VERSION), dtmcontrol);
diff --git a/src/target/riscv/riscv.c b/src/target/riscv/riscv.c
index a544cbd..a207a44 100644
--- a/src/target/riscv/riscv.c
+++ b/src/target/riscv/riscv.c
@@ -281,7 +281,7 @@ void select_dmi_via_bscan(struct target *target)
 										bscan_tunnel_nested_tap_select_dmi, TAP_IDLE);
 }
 
-uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out)
+int dtmcontrol_scan_via_bscan(struct target *target, uint32_t out, uint32_t *in_ptr)
 {
 	/* On BSCAN TAP: Select IR=USER4, issue tunneled IR scan via BSCAN TAP's DR */
 	uint8_t tunneled_ir_width[4] = {bscan_tunnel_ir_width};
@@ -362,18 +362,19 @@ uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out)
 	uint32_t in = buf_get_u32(in_value, 1, 32);
 	LOG_DEBUG("DTMCS: 0x%x -> 0x%x", out, in);
 
-	return in;
+	if (in_ptr)
+		*in_ptr = in;
+	return ERROR_OK;
 }
 
-static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
+static int dtmcontrol_scan(struct target *target, uint32_t out, uint32_t *in_ptr)
 {
 	struct scan_field field;
 	uint8_t in_value[4];
 	uint8_t out_value[4] = { 0 };
 
 	if (bscan_tunnel_ir_width != 0)
-		return dtmcontrol_scan_via_bscan(target, out);
-
+		return dtmcontrol_scan_via_bscan(target, out, in_ptr);
 
 	buf_set_u32(out_value, 0, 32, out);
 
@@ -389,14 +390,16 @@ static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
 
 	int retval = jtag_execute_queue();
 	if (retval != ERROR_OK) {
-		LOG_ERROR("failed jtag scan: %d", retval);
+		LOG_TARGET_ERROR(target, "dtmcontrol scan failed, error code = %d", retval);
 		return retval;
 	}
 
 	uint32_t in = buf_get_u32(field.in_value, 0, 32);
 	LOG_DEBUG("DTMCONTROL: 0x%x -> 0x%x", out, in);
 
-	return in;
+	if (in_ptr)
+		*in_ptr = in;
+	return ERROR_OK;
 }
 
 static struct target_type *get_target_type(struct target *target)
@@ -408,11 +411,13 @@ static struct target_type *get_target_type(struct target *target)
 
 	RISCV_INFO(info);
 	switch (info->dtm_version) {
-		case 0:
+		case DTM_DTMCS_VERSION_0_11:
 			return &riscv011_target;
-		case 1:
+		case DTM_DTMCS_VERSION_1_0:
 			return &riscv013_target;
 		default:
+			/* TODO: once we have proper support for non-examined targets
+			 * we should have an assert here */
 			LOG_TARGET_ERROR(target, "Unsupported DTM version: %d",
 					info->dtm_version);
 			return NULL;
@@ -479,6 +484,7 @@ static void riscv_free_registers(struct target *target)
 			free(target->reg_cache->reg_list);
 		}
 		free(target->reg_cache);
+		target->reg_cache = NULL;
 	}
 }
 
@@ -488,6 +494,8 @@ static void riscv_deinit_target(struct target *target)
 
 	struct riscv_info *info = target->arch_info;
 	struct target_type *tt = get_target_type(target);
+	if (!tt)
+		LOG_TARGET_ERROR(target, "Could not identify target type.");
 
 	if (riscv_flush_registers(target) != ERROR_OK)
 		LOG_TARGET_ERROR(target, "Failed to flush registers. Ignoring this error.");
@@ -1517,6 +1525,8 @@ static int oldriscv_step(struct target *target, int current, uint32_t address,
 		int handle_breakpoints)
 {
 	struct target_type *tt = get_target_type(target);
+	if (!tt)
+		return ERROR_FAIL;
 	return tt->step(target, current, address, handle_breakpoints);
 }
 
@@ -1542,25 +1552,40 @@ static int riscv_examine(struct target *target)
 	/* Don't need to select dbus, since the first thing we do is read dtmcontrol. */
 
 	RISCV_INFO(info);
-	uint32_t dtmcontrol = dtmcontrol_scan(target, 0);
+	uint32_t dtmcontrol;
+	if (dtmcontrol_scan(target, 0, &dtmcontrol) != ERROR_OK || dtmcontrol == 0) {
+		LOG_TARGET_ERROR(target, "Could not read dtmcontrol. Check JTAG connectivity/board power.");
+		return ERROR_FAIL;
+	}
 	LOG_TARGET_DEBUG(target, "dtmcontrol=0x%x", dtmcontrol);
 	info->dtm_version = get_field(dtmcontrol, DTMCONTROL_VERSION);
 	LOG_TARGET_DEBUG(target, "version=0x%x", info->dtm_version);
 
+	int examine_status = ERROR_FAIL;
 	struct target_type *tt = get_target_type(target);
 	if (!tt)
-		return ERROR_FAIL;
+		goto examine_fail;
 
-	int result = tt->init_target(info->cmd_ctx, target);
-	if (result != ERROR_OK)
-		return result;
+	examine_status = tt->init_target(info->cmd_ctx, target);
+	if (examine_status != ERROR_OK)
+		goto examine_fail;
+
+	examine_status = tt->examine(target);
+	if (examine_status != ERROR_OK)
+		goto examine_fail;
+
+	return ERROR_OK;
 
-	return tt->examine(target);
+examine_fail:
+	info->dtm_version = DTM_DTMCS_VERSION_UNKNOWN;
+	return examine_status;
 }
 
 static int oldriscv_poll(struct target *target)
 {
 	struct target_type *tt = get_target_type(target);
+	if (!tt)
+		return ERROR_FAIL;
 	return tt->poll(target);
 }
 
@@ -1694,6 +1719,8 @@ static int halt_go(struct target *target)
 	int result;
 	if (!r->get_hart_state) {
 		struct target_type *tt = get_target_type(target);
+		if (!tt)
+			return ERROR_FAIL;
 		result = tt->halt(target);
 	} else {
 		result = riscv_halt_go_all_harts(target);
@@ -1715,6 +1742,8 @@ int riscv_halt(struct target *target)
 
 	if (!r->get_hart_state) {
 		struct target_type *tt = get_target_type(target);
+		if (!tt)
+			return ERROR_FAIL;
 		return tt->halt(target);
 	}
 
@@ -1760,6 +1789,8 @@ static int riscv_assert_reset(struct target *target)
 {
 	LOG_TARGET_DEBUG(target, "coreid: [%d]", target->coreid);
 	struct target_type *tt = get_target_type(target);
+	if (!tt)
+		return ERROR_FAIL;
 	riscv_invalidate_register_cache(target);
 	return tt->assert_reset(target);
 }
@@ -1768,6 +1799,8 @@ static int riscv_deassert_reset(struct target *target)
 {
 	LOG_TARGET_DEBUG(target, "coreid: [%d]", target->coreid);
 	struct target_type *tt = get_target_type(target);
+	if (!tt)
+		return ERROR_FAIL;
 	return tt->deassert_reset(target);
 }
 
@@ -1900,6 +1933,8 @@ static int resume_go(struct target *target, int current,
 	int result;
 	if (!r->get_hart_state) {
 		struct target_type *tt = get_target_type(target);
+		if (!tt)
+			return ERROR_FAIL;
 		result = tt->resume(target, current, address, handle_breakpoints,
 				debug_execution);
 	} else {
@@ -2400,6 +2435,8 @@ static int riscv_write_phys_memory(struct target *target, target_addr_t phys_add
 			uint32_t size, uint32_t count, const uint8_t *buffer)
 {
 	struct target_type *tt = get_target_type(target);
+	if (!tt)
+		return ERROR_FAIL;
 	return tt->write_memory(target, phys_address, size, count, buffer);
 }
 
@@ -2416,6 +2453,8 @@ static int riscv_write_memory(struct target *target, target_addr_t address,
 		address = physical_addr;
 
 	struct target_type *tt = get_target_type(target);
+	if (!tt)
+		return ERROR_FAIL;
 	return tt->write_memory(target, address, size, count, buffer);
 }
 
@@ -2493,6 +2532,8 @@ static int riscv_get_gdb_reg_list(struct target *target,
 static int riscv_arch_state(struct target *target)
 {
 	struct target_type *tt = get_target_type(target);
+	if (!tt)
+		return ERROR_FAIL;
 	return tt->arch_state(target);
 }
 
@@ -4230,7 +4271,7 @@ COMMAND_HANDLER(riscv_exec_progbuf)
 	struct target *target = get_current_target(CMD_CTX);
 
 	RISCV_INFO(r);
-	if (r->dtm_version != 1) {
+	if (r->dtm_version != DTM_DTMCS_VERSION_1_0) {
 		LOG_TARGET_ERROR(target, "exec_progbuf: Program buffer is "
 				"only supported on v0.13 or v1.0 targets.");
 		return ERROR_FAIL;
@@ -4628,7 +4669,7 @@ static void riscv_info_init(struct target *target, struct riscv_info *r)
 
 	r->common_magic = RISCV_COMMON_MAGIC;
 
-	r->dtm_version = 1;
+	r->dtm_version = DTM_DTMCS_VERSION_UNKNOWN;
 	r->version_specific = NULL;
 
 	memset(r->trigger_unique_id, 0xff, sizeof(r->trigger_unique_id));
diff --git a/src/target/riscv/riscv.h b/src/target/riscv/riscv.h
index 3cf6aac..01e9932 100644
--- a/src/target/riscv/riscv.h
+++ b/src/target/riscv/riscv.h
@@ -111,10 +111,12 @@ typedef struct {
 	char *name;
 } range_list_t;
 
+#define DTM_DTMCS_VERSION_UNKNOWN ((unsigned int)-1)
+
 struct riscv_info {
 	unsigned int common_magic;
 
-	unsigned dtm_version;
+	unsigned int dtm_version;
 
 	struct command_context *cmd_ctx;
 	void *version_specific;
@@ -357,7 +359,7 @@ extern uint32_t bscan_tunneled_select_dmi_num_fields;
 typedef enum { BSCAN_TUNNEL_NESTED_TAP, BSCAN_TUNNEL_DATA_REGISTER } bscan_tunnel_type_t;
 extern int bscan_tunnel_ir_width;
 
-uint32_t dtmcontrol_scan_via_bscan(struct target *target, uint32_t out);
+int dtmcontrol_scan_via_bscan(struct target *target, uint32_t out, uint32_t *in_ptr);
 void select_dmi_via_bscan(struct target *target);
 
 /*** OpenOCD Interface */