Here is a list of all files with brief descriptions:

include
mbedtls
aes.h	This file contains AES definitions and functions
aria.h	ARIA block cipher
asn1.h	Generic ASN.1 parsing
asn1write.h	ASN.1 buffer writing functionality
base64.h	RFC 1521 base64 encoding/decoding
bignum.h	Multi-precision integer library
block_cipher.h	Internal abstraction layer
build_info.h	Build-time configuration info
camellia.h	Camellia block cipher
ccm.h	This file provides an API for the CCM authenticated encryption mode for block ciphers
chacha20.h	This file contains ChaCha20 definitions and functions
chachapoly.h	This file contains the AEAD-ChaCha20-Poly1305 definitions and functions
check_config.h	Consistency checks for configuration options
cipher.h	This file contains an abstraction interface for use with the cipher primitives provided by the library. It provides a common interface to all of the available cipher operations
cmac.h	This file contains CMAC definitions and functions
compat-2.x.h	Compatibility definitions
config_adjust_legacy_crypto.h	Adjust legacy configuration configuration
config_adjust_legacy_from_psa.h	Adjust PSA configuration: activate legacy implementations
config_adjust_psa_from_legacy.h	Adjust PSA configuration: construct PSA configuration from legacy
config_adjust_psa_superset_legacy.h	Adjust PSA configuration: automatic enablement from legacy
config_adjust_ssl.h	Adjust TLS configuration
config_adjust_x509.h	Adjust X.509 configuration
config_psa.h	PSA crypto configuration options (set of defines)
constant_time.h
ctr_drbg.h	This file contains definitions and functions for the CTR_DRBG pseudorandom generator
debug.h	Functions for controlling and providing debug output from the library
des.h	DES block cipher
dhm.h	This file contains Diffie-Hellman-Merkle (DHM) key exchange definitions and functions
ecdh.h	This file contains ECDH definitions and functions
ecdsa.h	This file contains ECDSA definitions and functions
ecjpake.h	Elliptic curve J-PAKE
ecp.h	This file provides an API for Elliptic Curves over GF(P) (ECP)
entropy.h	Entropy accumulator implementation
error.h	Error to string translation
gcm.h	This file contains GCM definitions and functions
hkdf.h	This file contains the HKDF interface
hmac_drbg.h	The HMAC_DRBG pseudorandom generator
lms.h	This file provides an API for the LMS post-quantum-safe stateful-hash public-key signature scheme as defined in RFC8554 and NIST.SP.200-208. This implementation currently only supports a single parameter set MBEDTLS_LMS_SHA256_M32_H10 in order to reduce complexity. This is one of the signature schemes recommended by the IETF draft SUIT standard for IOT firmware upgrades (RFC9019)
mbedtls_config.h	Configuration options (set of defines)
md.h	This file contains the generic functions for message-digest (hashing) and HMAC
md5.h	MD5 message digest algorithm (hash function)
memory_buffer_alloc.h	Buffer-based memory allocator
net_sockets.h	Network sockets abstraction layer to integrate Mbed TLS into a BSD-style sockets API
nist_kw.h	This file provides an API for key wrapping (KW) and key wrapping with padding (KWP) as defined in NIST SP 800-38F. https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-38F.pdf
oid.h	Object Identifier (OID) database
pem.h	Privacy Enhanced Mail (PEM) decoding
pk.h	Public Key abstraction layer
pkcs12.h	PKCS#12 Personal Information Exchange Syntax
pkcs5.h	PKCS#5 functions
pkcs7.h	PKCS #7 generic defines and structures https://tools.ietf.org/html/rfc2315
platform.h	This file contains the definitions and functions of the Mbed TLS platform abstraction layer
platform_time.h	Mbed TLS Platform time abstraction
platform_util.h	Common and shared functions used by multiple modules in the Mbed TLS library
poly1305.h	This file contains Poly1305 definitions and functions
private_access.h	Macro wrapper for struct's members
psa_util.h	Utility functions for the use of the PSA Crypto library
ripemd160.h	RIPE MD-160 message digest
rsa.h	This file provides an API for the RSA public-key cryptosystem
sha1.h	This file contains SHA-1 definitions and functions
sha256.h	This file contains SHA-224 and SHA-256 definitions and functions
sha3.h	This file contains SHA-3 definitions and functions
sha512.h	This file contains SHA-384 and SHA-512 definitions and functions
ssl.h	SSL/TLS functions
ssl_cache.h	SSL session cache implementation
ssl_ciphersuites.h	SSL Ciphersuites for Mbed TLS
ssl_cookie.h	DTLS cookie callbacks implementation
ssl_ticket.h	TLS server ticket callbacks implementation
threading.h	Threading abstraction layer
timing.h	Portable interface to timeouts and to the CPU cycle counter
version.h	Run-time version information
x509.h	X.509 generic defines and structures
x509_crl.h	X.509 certificate revocation list parsing
x509_crt.h	X.509 certificate parsing and writing
x509_csr.h	X.509 certificate signing request parsing and writing
psa
build_info.h	Build-time PSA configuration info
crypto.h	Platform Security Architecture cryptography module
crypto_adjust_auto_enabled.h	Adjust PSA configuration: enable always-on features
crypto_adjust_config_dependencies.h	Adjust PSA configuration by resolving some dependencies
crypto_adjust_config_key_pair_types.h	Adjust PSA configuration for key pair types
crypto_adjust_config_synonyms.h	Adjust PSA configuration: enable quasi-synonyms
crypto_builtin_composites.h
crypto_builtin_key_derivation.h
crypto_builtin_primitives.h
crypto_compat.h	PSA cryptography module: Backward compatibility aliases
crypto_config.h	PSA crypto configuration options (set of defines)
crypto_driver_common.h	Definitions for all PSA crypto drivers
crypto_driver_contexts_composites.h
crypto_driver_contexts_key_derivation.h
crypto_driver_contexts_primitives.h
crypto_extra.h	PSA cryptography module: Mbed TLS vendor extensions
crypto_legacy.h	Add temporary suppport for deprecated symbols before they are removed from the library
crypto_platform.h	PSA cryptography module: Mbed TLS platform definitions
crypto_se_driver.h	PSA external cryptoprocessor driver module
crypto_sizes.h	PSA cryptography module: Mbed TLS buffer size macros
crypto_struct.h	PSA cryptography module: Mbed TLS structured type implementations
crypto_types.h	PSA cryptography module: type aliases
crypto_values.h	PSA cryptography module: macros to build and analyze integer values
input
doc_encdec.h	Encryption/decryption module documentation file
doc_hashing.h	Hashing module documentation file
doc_mainpage.h	Main page documentation file
doc_rng.h	Random number generator (RNG) module documentation file
doc_ssltls.h	SSL/TLS communication module documentation file
doc_tcpip.h	TCP/IP communication module documentation file
doc_x509.h	X.509 module documentation file
tests
include
alt-dummy
aes_alt.h
aria_alt.h
camellia_alt.h
ccm_alt.h
chacha20_alt.h
chachapoly_alt.h
cmac_alt.h
des_alt.h
dhm_alt.h
ecjpake_alt.h
ecp_alt.h
gcm_alt.h
md5_alt.h
nist_kw_alt.h
platform_alt.h
poly1305_alt.h
ripemd160_alt.h
rsa_alt.h
sha1_alt.h
sha256_alt.h
sha512_alt.h
threading_alt.h
timing_alt.h