dfu: Introduction of the "dfu_hash_algo" env variable for checksum method setting

Up till now the CRC32 of received data was calculated unconditionally.
The standard crc32 implementation causes long delay when large images
were uploaded.

The "dfu_hash_algo" environment variable gives the opportunity to
disable on demand the hash (crc32) calculation.
It can be done without the need to recompile the u-boot binary.

By default the crc32 is calculated, which means that legacy behavior
has been preserved.

Tests results:
400 MiB ums.img file
With 		crc32 calculation: 65 sec [avg 6.29 MB/s]
Without 		crc32 calculation: 25 sec [avg 16.17 MB/s]

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Cc: Marek Vasut <marex@denx.de>

drivers/dfu/dfu.c

@@ -13,6 +13,7 @@
 #include <mmc.h>
 #include <fat.h>
 #include <dfu.h>
+#include <hash.h>
 #include <linux/list.h>
 #include <linux/compiler.h>
 
@@ -20,6 +21,7 @@ static bool dfu_reset_request;
 static LIST_HEAD(dfu_list);
 static int dfu_alt_num;
 static int alt_num_cnt;
+static struct hash_algo *dfu_hash_algo;
 
 bool dfu_reset(void)
 {
@@ -99,6 +101,29 @@ unsigned char *dfu_get_buf(void)
 	return dfu_buf;
 }
 
+static char *dfu_get_hash_algo(void)
+{
+	char *s;
+
+	s = getenv("dfu_hash_algo");
+	/*
+	 * By default the legacy behaviour to calculate the crc32 hash
+	 * value is preserved.
+	 *
+	 * To disable calculation of the hash algorithm for received data
+	 * specify the "dfu_hash_algo = disabled" at your board envs.
+	 */
+	debug("%s: DFU hash method: %s\n", __func__, s ? s : "not specified");
+
+	if (!s || !strcmp(s, "crc32"))
+		return "crc32";
+
+	if (!strcmp(s, "disabled"))
+		return NULL;
+
+	return NULL;
+}
+
 static int dfu_write_buffer_drain(struct dfu_entity *dfu)
 {
 	long w_size;
@@ -109,8 +134,9 @@ static int dfu_write_buffer_drain(struct dfu_entity *dfu)
 	if (w_size == 0)
 		return 0;
 
-	/* update CRC32 */
-	dfu->crc = crc32(dfu->crc, dfu->i_buf_start, w_size);
+	if (dfu_hash_algo)
+		dfu_hash_algo->hash_update(dfu_hash_algo, &dfu->crc,
+					   dfu->i_buf_start, w_size, 0);
 
 	ret = dfu->write_medium(dfu, dfu->offset, dfu->i_buf_start, &w_size);
 	if (ret)
@@ -138,7 +164,9 @@ int dfu_flush(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
 	if (dfu->flush_medium)
 		ret = dfu->flush_medium(dfu);
 
-	printf("\nDFU complete CRC32: 0x%08x\n", dfu->crc);
+	if (dfu_hash_algo)
+		printf("\nDFU complete %s: 0x%08x\n", dfu_hash_algo->name,
+		       dfu->crc);
 
 	/* clear everything */
 	dfu_free_buf();
@@ -238,7 +266,11 @@ static int dfu_read_buffer_fill(struct dfu_entity *dfu, void *buf, int size)
 		/* consume */
 		if (chunk > 0) {
 			memcpy(buf, dfu->i_buf, chunk);
-			dfu->crc = crc32(dfu->crc, buf, chunk);
+			if (dfu_hash_algo)
+				dfu_hash_algo->hash_update(dfu_hash_algo,
+							   &dfu->crc, buf,
+							   chunk, 0);
+
 			dfu->i_buf += chunk;
 			dfu->b_left -= chunk;
 			dfu->r_left -= chunk;
@@ -322,7 +354,9 @@ int dfu_read(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
 	}
 
 	if (ret < size) {
-		debug("%s: %s CRC32: 0x%x\n", __func__, dfu->name, dfu->crc);
+		if (dfu_hash_algo)
+			debug("%s: %s %s: 0x%x\n", __func__, dfu->name,
+			      dfu_hash_algo->name, dfu->crc);
 		puts("\nUPLOAD ... done\nCtrl+C to exit ...\n");
 
 		dfu_free_buf();
@@ -397,6 +431,14 @@ int dfu_config_entities(char *env, char *interface, int num)
 	dfu_alt_num = dfu_find_alt_num(env);
 	debug("%s: dfu_alt_num=%d\n", __func__, dfu_alt_num);
 
+	dfu_hash_algo = NULL;
+	s = dfu_get_hash_algo();
+	if (s) {
+		ret = hash_lookup_algo(s, &dfu_hash_algo);
+		if (ret)
+			error("Hash algorithm %s not supported\n", s);
+	}
+
 	dfu = calloc(sizeof(*dfu), dfu_alt_num);
 	if (!dfu)
 		return -1;