hash: Add a way to calculate a hash for any algortihm

Rather than needing to call one of many hashing algorithms in U-Boot,
provide a function hash_block() which handles this, and can support all
available hash algorithms.

Once we have md5 supported within hashing, we can use this function in
the FIT image code.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/hash.c

@@ -30,6 +30,7 @@
 #include <sha1.h>
 #include <sha256.h>
 #include <asm/io.h>
+#include <asm/errno.h>
 
 /*
  * These are the hash algorithms we support. Chips which support accelerated
@@ -238,6 +239,28 @@ static void show_hash(struct hash_algo *algo, ulong addr, ulong len,
 		printf("%02x", output[i]);
 }
 
+int hash_block(const char *algo_name, const void *data, unsigned int len,
+	       uint8_t *output, int *output_size)
+{
+	struct hash_algo *algo;
+
+	algo = find_hash_algo(algo_name);
+	if (!algo) {
+		debug("Unknown hash algorithm '%s'\n", algo_name);
+		return -EPROTONOSUPPORT;
+	}
+	if (output_size && *output_size < algo->digest_size) {
+		debug("Output buffer size %d too small (need %d bytes)",
+		      *output_size, algo->digest_size);
+		return -ENOSPC;
+	}
+	if (output_size)
+		*output_size = algo->digest_size;
+	algo->hash_func_ws(data, len, output, algo->chunk_size);
+
+	return 0;
+}
+
 int hash_command(const char *algo_name, int flags, cmd_tbl_t *cmdtp, int flag,
 		 int argc, char * const argv[])
 {

include/hash.h

@@ -71,4 +71,26 @@ enum {
 int hash_command(const char *algo_name, int flags, cmd_tbl_t *cmdtp, int flag,
 		 int argc, char * const argv[]);
 
+/**
+ * hash_block() - Hash a block according to the requested algorithm
+ *
+ * The caller probably knows the hash length for the chosen algorithm, but
+ * in order to provide a general interface, and output_size parameter is
+ * provided.
+ *
+ * @algo_name:		Hash algorithm to use
+ * @data:		Data to hash
+ * @len:		Lengh of data to hash in bytes
+ * @output:		Place to put hash value
+ * @output_size:	On entry, pointer to the number of bytes available in
+ *			output. On exit, pointer to the number of bytes used.
+ *			If NULL, then it is assumed that the caller has
+ *			allocated enough space for the hash. This is possible
+ *			since the caller is selecting the algorithm.
+ * @return 0 if ok, -ve on error: -EPROTONOSUPPORT for an unknown algorithm,
+ * -ENOSPC if the output buffer is not large enough.
+ */
+int hash_block(const char *algo_name, const void *data, unsigned int len,
+	       uint8_t *output, int *output_size);
+
 #endif