Add proper SPD definitions for DDR1/2/3

Also adds helper functions for DDR1/2 to verify the checksum.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

common/ddr_spd.c

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2008 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * Version 2 as published by the Free Software Foundation.
+ */
+
+#include <common.h>
+#include <ddr_spd.h>
+
+/* used for ddr1 and ddr2 spd */
+static int
+spd_check(const u8 *buf, u8 spd_rev, u8 spd_cksum)
+{
+	unsigned int cksum = 0;
+	unsigned int i;
+
+	/*
+	 * Check SPD revision supported
+	 * Rev 1.2 or less supported by this code
+	 */
+	if (spd_rev > 0x12) {
+		printf("SPD revision %02X not supported by this code\n",
+		       spd_rev);
+		return 1;
+	}
+
+	/*
+	 * Calculate checksum
+	 */
+	for (i = 0; i < 63; i++) {
+		cksum += *buf++;
+	}
+	cksum &= 0xFF;
+
+	if (cksum != spd_cksum) {
+		printf("SPD checksum unexpected. "
+			"Checksum in SPD = %02X, computed SPD = %02X\n",
+			spd_cksum, cksum);
+		return 1;
+	}
+
+	return 0;
+}
+
+unsigned int
+ddr1_spd_check(const ddr1_spd_eeprom_t *spd)
+{
+	const u8 *p = (const u8 *)spd;
+
+	return spd_check(p, spd->spd_rev, spd->cksum);
+}
+
+unsigned int
+ddr2_spd_check(const ddr2_spd_eeprom_t *spd)
+{
+	const u8 *p = (const u8 *)spd;
+
+	return spd_check(p, spd->spd_rev, spd->cksum);
+}