Bluetooth: ATT: Add documentation for ATT error codes

Add the description of each error code as defined by the
core spec and the CSS.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>

include/zephyr/bluetooth/att.h

@@ -24,32 +24,71 @@
 extern "C" {
 #endif
 
-/* Error codes for Error response PDU */
+/* Error codes for Error response PDU
+ *
+ * Defined by The Bluetooth Core Specification, Version 5.4, Vol 3, Part F, Section 3.4.1.1
+ */
+/** The ATT operation was successful */
 #define BT_ATT_ERR_SUCCESS			0x00
+/** The attribute handle given was not valid on the server */
 #define BT_ATT_ERR_INVALID_HANDLE		0x01
+/** The attribute cannot be read */
 #define BT_ATT_ERR_READ_NOT_PERMITTED		0x02
+/** The attribute cannot be written */
 #define BT_ATT_ERR_WRITE_NOT_PERMITTED		0x03
+/** The attribute PDU was invalid */
 #define BT_ATT_ERR_INVALID_PDU			0x04
+/** The attribute requires authentication before it can be read or written */
 #define BT_ATT_ERR_AUTHENTICATION		0x05
+/** The ATT Server does not support the request received from the client */
 #define BT_ATT_ERR_NOT_SUPPORTED		0x06
+/** Offset specified was past the end of the attribute */
 #define BT_ATT_ERR_INVALID_OFFSET		0x07
+/** The attribute requires authorization before it can be read or written */
 #define BT_ATT_ERR_AUTHORIZATION		0x08
+/** Too many prepare writes have been queued */
 #define BT_ATT_ERR_PREPARE_QUEUE_FULL		0x09
+/** No attribute found within the given attribute handle range */
 #define BT_ATT_ERR_ATTRIBUTE_NOT_FOUND		0x0a
+/** The attribute cannot be read using the ATT_READ_BLOB_REQ PDU */
 #define BT_ATT_ERR_ATTRIBUTE_NOT_LONG		0x0b
+/** The Encryption Key Size used for encrypting this link is too short */
 #define BT_ATT_ERR_ENCRYPTION_KEY_SIZE		0x0c
+/** The attribute value length is invalid for the operation */
 #define BT_ATT_ERR_INVALID_ATTRIBUTE_LEN	0x0d
+/**
+ * @brief The attribute request that was requested has encountered an error that was unlikely
+ *
+ * The attribute request could therefore not be completed as requested
+ */
 #define BT_ATT_ERR_UNLIKELY			0x0e
+/** The attribute requires encryption before it can be read or written */
 #define BT_ATT_ERR_INSUFFICIENT_ENCRYPTION	0x0f
+/**
+ * @brief The attribute type is not a supported grouping attribute
+ *
+ * The attribute type is not a supported grouping attribute as defined by a higher layer
+ * specification.
+ */
 #define BT_ATT_ERR_UNSUPPORTED_GROUP_TYPE	0x10
+/** Insufficient Resources to complete the request */
 #define BT_ATT_ERR_INSUFFICIENT_RESOURCES	0x11
+/** The server requests the client to rediscover the database */
 #define BT_ATT_ERR_DB_OUT_OF_SYNC		0x12
+/** The attribute parameter value was not allowed */
 #define BT_ATT_ERR_VALUE_NOT_ALLOWED		0x13
 
-/* Common Profile Error Codes (from CSS) */
+/* Common Profile Error Codes
+ *
+ * Defined by the Supplement to the Bluetooth Core Specification (CSS), v11, Part B, Section 1.2.
+ */
+/** Write Request Rejected */
 #define BT_ATT_ERR_WRITE_REQ_REJECTED		0xfc
+/** Client Characteristic Configuration Descriptor Improperly Configured */
 #define BT_ATT_ERR_CCC_IMPROPER_CONF		0xfd
+/** Procedure Already in Progress */
 #define BT_ATT_ERR_PROCEDURE_IN_PROGRESS	0xfe
+/** Out of Range */
 #define BT_ATT_ERR_OUT_OF_RANGE			0xff
 
 /* Version 5.2, Vol 3, Part F, 3.2.9 defines maximum attribute length to 512 */