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authorRenaud Barbier <renaud.barbier@ge.com>2013-06-26 18:33:40 +0100
committerSascha Hauer <s.hauer@pengutronix.de>2013-06-27 08:38:04 +0200
commite06aa069652c99f5951f2e89a3af952aa484a3bc (patch)
treec258eedae2efacc1df1143d1bf10cccfed2c639b /common/ddr_spd.c
parent9bd04c9adb6f0adaf408773d114d0f183e8f6943 (diff)
downloadbarebox-e06aa069652c99f5951f2e89a3af952aa484a3bc.tar.gz
common: DDR2 SPD checksum.
The code calculates the DDR2 SPD checksum as per JEDEC standard No 21-C Appendix X (revision 1.2) The code is based on the equivalent files from U-Boot version git-a71d45d. Signed-off-by: Renaud Barbier <renaud.barbier@ge.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'common/ddr_spd.c')
-rw-r--r--common/ddr_spd.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/common/ddr_spd.c b/common/ddr_spd.c
new file mode 100644
index 0000000..c8b73ff
--- /dev/null
+++ b/common/ddr_spd.c
@@ -0,0 +1,39 @@
+/*
+ * 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>
+
+uint32_t ddr2_spd_checksum_pass(const struct ddr2_spd_eeprom_s *spd)
+{
+ uint32_t i, cksum = 0;
+ const uint8_t *buf = (const uint8_t *)spd;
+ uint8_t rev, spd_cksum;
+
+ rev = spd->spd_rev;
+ spd_cksum = spd->cksum;
+
+ /* Rev 1.X or less supported by this code */
+ if (rev >= 0x20)
+ goto error;
+
+ /*
+ * The checksum is calculated on the first 64 bytes
+ * of the SPD as per JEDEC specification.
+ */
+ for (i = 0; i < 63; i++)
+ cksum += *buf++;
+ cksum &= 0xFF;
+
+ if (cksum != spd_cksum)
+ goto error;
+
+ return 0;
+error:
+ return 1;
+}