[ujson] add functions to pad device->host strings

This adds UJSON serialization functions to enable transmitting fixed
size UJSON strings from the device --> host. This will be useful for
provisioning flows in ATE environments.

Signed-off-by: Tim Trippel <[email protected]>
(cherry picked from commit 3b354ff)

Author: timothytrippel

sw/device/lib/testing/test_framework/ujson_ottf.h

@@ -108,6 +108,23 @@ ujson_t ujson_ottf_console(void);
     OK_STATUS();                                   \
   })
 
+/**
+ * Respond with an OK result, JSON encoded data padded to specific size, and
+ * empty CRC.
+ *
+ * @param responder_ A ujson serializer function for `data_`.
+ * @param uj_ctx_ A `ujson_t` representing the IO context.
+ * @param data_ A pointer to the data to send.
+ * @param max_size_ Max size the payload should be padded to.
+ */
+#define RESP_OK_PADDED_NO_CRC(responder_, uj_ctx_, data_, max_size_) \
+  ({                                                                 \
+    TRY(ujson_putbuf(uj_ctx_, "RESP_OK:", 8));                       \
+    TRY(responder_(uj_ctx_, data_, max_size_));                      \
+    RESP_NO_CRC(uj_ctx_);                                            \
+    OK_STATUS();                                                     \
+  })
+
 /**
  * Respond with an OK result, JSON encoded data, and valid CRC.
  *

sw/device/lib/ujson/ujson.c

@@ -28,6 +28,7 @@ void ujson_crc32_reset(ujson_t *uj) { crc32_init(&uj->crc32); }
 uint32_t ujson_crc32_finish(ujson_t *uj) { return crc32_finish(&uj->crc32); }
 
 status_t ujson_putbuf(ujson_t *uj, const char *buf, size_t len) {
+  uj->str_size += len;
   crc32_add(&uj->crc32, buf, len);
   return uj->putbuf(uj->io_context, buf, len);
 }

sw/device/lib/ujson/ujson_derive.h

@@ -119,6 +119,22 @@
         if (--nfield) TRY(ujson_putbuf(uj, ",", 1)); \
     }
 
+#define UJSON_IMPL_SERIALIZE_STRUCT_WITH_PADDING(name_, decl_) \
+    status_t ujson_serialize_with_padding_##name_(ujson_t *uj, const name_ *self, size_t max_size) { \
+        size_t nfield = decl_(ujson_count, ujson_count); \
+        uj->str_size = 0; \
+        TRY(ujson_putbuf(uj, "{", 1)); \
+        decl_(ujson_ser_field, ujson_ser_string) \
+        if (max_size > uj->str_size + 1) { \
+          for (size_t i = 0; i < max_size - uj->str_size - 1; i++) { \
+            TRY(ujson_putbuf(uj, " ", 1)); \
+          } \
+        } \
+        TRY(ujson_putbuf(uj, "}", 1)); \
+        return OK_STATUS(); \
+    } \
+    extern const int __never_referenced___here_to_eat_a_semicolon[]
+
 #define UJSON_IMPL_SERIALIZE_STRUCT(name_, decl_) \
     status_t ujson_serialize_##name_(ujson_t *uj, const name_ *self) { \
         size_t nfield = decl_(ujson_count, ujson_count); \
@@ -266,6 +282,14 @@
         status_t ujson_serialize_##name_(ujson_t *uj, const name_ *self) \
     ) /*endif*/
 
+#define UJSON_SERIALIZE_STRUCT_WITH_PADDING(name_, decl_) \
+    OT_IIF(UJSON_SERDE_IMPL) \
+    ( /*then*/ \
+        UJSON_IMPL_SERIALIZE_STRUCT_WITH_PADDING(name_, decl_) \
+    , /*else*/ \
+        status_t ujson_serialize_with_padding_##name_(ujson_t *uj, const name_ *self, size_t max_size) \
+    ) /*endif*/
+
 #define UJSON_SERIALIZE_ENUM(formal_name_, name_, decl_, ...) \
     OT_IIF(UJSON_SERDE_IMPL) \
     ( /*then*/ \
@@ -297,6 +321,7 @@
 #define UJSON_SERDE_STRUCT(formal_name_, name_, decl_, ...)        \
   UJSON_DECLARE_STRUCT(formal_name_, name_, decl_, ##__VA_ARGS__); \
   UJSON_SERIALIZE_STRUCT(name_, decl_);                            \
+  UJSON_SERIALIZE_STRUCT_WITH_PADDING(name_, decl_);               \
   UJSON_DESERIALIZE_STRUCT(name_, decl_)
 
 #define UJSON_SERDE_ENUM(formal_name_, name_, decl_, ...)          \

sw/device/silicon_creator/manuf/tests/ujson_msg_padding_functest.c

@@ -84,12 +84,16 @@ static status_t send_ujson_msgs(ujson_t *uj) {
     perso_blob_msg.body[i] = 0x5;
   }
 
-  // TX payloads to the host.
-  RESP_OK_NO_CRC(ujson_serialize_serdes_sha256_hash_t, uj, &sha256_hash_msg);
-  RESP_OK_NO_CRC(ujson_serialize_lc_token_hash_t, uj, &lc_token_hash_msg);
-  RESP_OK_NO_CRC(ujson_serialize_manuf_certgen_inputs_t, uj,
-                 &certgen_inputs_msg);
-  RESP_OK_NO_CRC(ujson_serialize_perso_blob_t, uj, &perso_blob_msg);
+  // TX payloads to the host padding the payloads with whitespace.
+  RESP_OK_PADDED_NO_CRC(ujson_serialize_with_padding_serdes_sha256_hash_t, uj,
+                        &sha256_hash_msg, kSerdesSha256HashSerializedMaxSize);
+  RESP_OK_PADDED_NO_CRC(ujson_serialize_with_padding_lc_token_hash_t, uj,
+                        &lc_token_hash_msg, kLcTokenHashSerializedMaxSize);
+  RESP_OK_PADDED_NO_CRC(ujson_serialize_with_padding_manuf_certgen_inputs_t, uj,
+                        &certgen_inputs_msg,
+                        kManufCertgenInputsSerializedMaxSize);
+  RESP_OK_PADDED_NO_CRC(ujson_serialize_with_padding_perso_blob_t, uj,
+                        &perso_blob_msg, kPersoBlobSerializedMaxSize);
 
   // RX payloads echoed back by host and check their sizes when received.
   TRY(ujson_deserialize_serdes_sha256_hash_t(uj, &sha256_hash_msg));

sw/host/provisioning/ujson_lib/src/lib.rs

@@ -11,6 +11,9 @@ pub mod provisioning_data;
 /// The are obtained by running the following FPGA test:
 /// bazel test --test_output=streamed \
 ///  //sw/device/silicon_creator/manuf/tests:ujson_msg_size_functest
+///
+/// These should match the constants in:
+/// sw/device/lib/testing/json/provisioning_data.h
 pub const SERDES_SHA256_HASH_SERIALIZED_MAX_SIZE: usize = 98;
 pub const LC_TOKEN_HASH_SERIALIZED_MAX_SIZE: usize = 52;
 pub const MANUF_CERTGEN_INPUTS_SERIALIZED_MAX_SIZE: usize = 210;