Fix memory access on some targets. (#428)

Fix memory access on 64-bit targets with no progbuf and sba that
supports 32-bit accesses but not 64-bit accesses. Bug was introduced in #419.

This fixes https://github.com/riscv/riscv-tests/issues/217.

Change-Id: Ib5ddf9886b77e3d58fe1d891b560ad03d5a46da1

src/target/riscv/riscv-013.c

@@ -1727,6 +1727,29 @@ static int riscv013_hart_count(struct target *target)
 	return dm->hart_count;
 }
 
+static unsigned riscv013_data_bits(struct target *target)
+{
+	RISCV013_INFO(info);
+	/* TODO: Once there is a spec for discovering abstract commands, we can
+	 * take those into account as well.  For now we assume abstract commands
+	 * support XLEN-wide accesses. */
+	if (info->progbufsize >= 2 && !riscv_prefer_sba)
+		return riscv_xlen(target);
+
+	if (get_field(info->sbcs, DMI_SBCS_SBACCESS128))
+		return 128;
+	if (get_field(info->sbcs, DMI_SBCS_SBACCESS64))
+		return 64;
+	if (get_field(info->sbcs, DMI_SBCS_SBACCESS32))
+		return 32;
+	if (get_field(info->sbcs, DMI_SBCS_SBACCESS16))
+		return 16;
+	if (get_field(info->sbcs, DMI_SBCS_SBACCESS8))
+		return 8;
+
+	return riscv_xlen(target);
+}
+
 static int init_target(struct command_context *cmd_ctx,
 		struct target *target)
 {
@@ -1759,6 +1782,7 @@ static int init_target(struct command_context *cmd_ctx,
 	generic_info->test_sba_config_reg = &riscv013_test_sba_config_reg;
 	generic_info->test_compliance = &riscv013_test_compliance;
 	generic_info->hart_count = &riscv013_hart_count;
+	generic_info->data_bits = &riscv013_data_bits;
 	generic_info->version_specific = calloc(1, sizeof(riscv013_info_t));
 	if (!generic_info->version_specific)
 		return ERROR_FAIL;

src/target/riscv/riscv.c

@@ -2462,6 +2462,14 @@ static unsigned riscv_xlen_nonconst(struct target *target)
 	return riscv_xlen(target);
 }
 
+static unsigned riscv_data_bits(struct target *target)
+{
+	RISCV_INFO(r);
+	if (r->data_bits)
+		return r->data_bits(target);
+	return riscv_xlen(target);
+}
+
 struct target_type riscv_target = {
 	.name = "riscv",
 
@@ -2501,7 +2509,7 @@ struct target_type riscv_target = {
 	.commands = riscv_command_handlers,
 
 	.address_bits = riscv_xlen_nonconst,
-	.data_bits = riscv_xlen_nonconst
+	.data_bits = riscv_data_bits
 };
 
 /*** RISC-V Interface ***/

src/target/riscv/riscv.h

@@ -146,6 +146,7 @@ typedef struct {
 
 	/* How many harts are attached to the DM that this target is attached to? */
 	int (*hart_count)(struct target *target);
+	unsigned (*data_bits)(struct target *target);
 } riscv_info_t;
 
 typedef struct {

src/target/target_type.h

@@ -297,9 +297,9 @@ struct target_type {
 	 * implemented, it's assumed to be 32. */
 	unsigned (*address_bits)(struct target *target);
 
-	/* Return the number of data bits this target supports. This will
-	 * typically be 32 for 32-bit targets, and 64 for 64-bit targets. If not
-	 * implemented, it's assumed to be 32. */
+	/* Return the number of system bus data bits this target supports. This
+	 * will typically be 32 for 32-bit targets, and 64 for 64-bit targets. If
+	 * not implemented, it's assumed to be 32. */
 	unsigned (*data_bits)(struct target *target);
 };