Add generic hash API

We have a SHA1 command and want to add a SHA256 command also. Instead of
duplicating the code, create a generic hash API which can process
commands for different algorithms.

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

include/hash.h

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2012 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef _HASH_H
+#define _HASH_H
+
+#ifdef CONFIG_SHA1SUM_VERIFY
+#define CONFIG_HASH_VERIFY
+#endif
+
+struct hash_algo {
+	const char *name;			/* Name of algorithm */
+	int digest_size;			/* Length of digest */
+	/**
+	 * hash_func_ws: Generic hashing function
+	 *
+	 * This is the generic prototype for a hashing function. We only
+	 * have the watchdog version at present.
+	 *
+	 * @input:	Input buffer
+	 * @ilen:	Input buffer length
+	 * @output:	Checksum result (length depends on algorithm)
+	 * @chunk_sz:	Trigger watchdog after processing this many bytes
+	 */
+	void (*hash_func_ws)(const unsigned char *input, unsigned int ilen,
+		unsigned char *output, unsigned int chunk_sz);
+	int chunk_size;				/* Watchdog chunk size */
+};
+
+/*
+ * Maximum digest size for all algorithms we support. Having this value
+ * avoids a malloc() or C99 local declaration in common/cmd_hash.c.
+ */
+#define HASH_MAX_DIGEST_SIZE	32
+
+/**
+ * hash_command: Process a hash command for a particular algorithm
+ *
+ * This common function is used to implement specific hash commands.
+ *
+ * @algo_name:		Hash algorithm being used
+ * @verify:		Non-zero to enable verify mode
+ * @cmdtp:		Pointer to command table entry
+ * @flag:		Some flags normally 0 (see CMD_FLAG_.. above)
+ * @argc:		Number of arguments (arg 0 must be the command text)
+ * @argv:		Arguments
+ */
+int hash_command(const char *algo_name, int verify, cmd_tbl_t *cmdtp, int flag,
+		 int argc, char * const argv[]);
+
+#endif