[U-Boot] [PATCH 02/10] x86: Add checksum implementation

[Simon Glass]

Add a checksum implementation that can be used with CMOS RAM.

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

 arch/x86/cpu/Makefile              |  1 +
 arch/x86/cpu/ip_checksum.c         | 61 ++++++++++++++++++++++++++++++++++++++
 arch/x86/include/asm/ip_checksum.h | 16 ++++++++++
 3 files changed, 78 insertions(+)
 create mode 100644 arch/x86/cpu/ip_checksum.c
 create mode 100644 arch/x86/include/asm/ip_checksum.h

diff --git a/arch/x86/cpu/Makefile b/arch/x86/cpu/Makefile
index 62e43c0..eee2289 100644
--- a/arch/x86/cpu/Makefile
+++ b/arch/x86/cpu/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_SYS_COREBOOT) += coreboot/
 obj-$(CONFIG_NORTHBRIDGE_INTEL_SANDYBRIDGE) += ivybridge/
 obj-$(CONFIG_NORTHBRIDGE_INTEL_IVYBRIDGE) += ivybridge/
 obj-$(CONFIG_INTEL_QUEENSBAY) += queensbay/
+obj-y += ip_checksum.o
 obj-y += lapic.o
 obj-y += mtrr.o
 obj-$(CONFIG_PCI) += pci.o
diff --git a/arch/x86/cpu/ip_checksum.c b/arch/x86/cpu/ip_checksum.c
new file mode 100644
index 0000000..17f9417
--- /dev/null
+++ b/arch/x86/cpu/ip_checksum.c
@@ -0,0 +1,61 @@
+/*
+ * From Coreboot compute_ip_checksum.c
+ *
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#include <common.h>
+#include <asm/ip_checksum.h>
+
+/* This function is functionally the same as NetCksum() - should we unify? */
+unsigned long compute_ip_checksum(void *addr, unsigned long length)
+{
+	uint8_t *ptr;
+	union {
+		uint8_t  byte[2];
+		uint16_t word;
+	} value;
+	unsigned long sum;
+	unsigned long i;
+
+	sum = 0;
+	ptr = addr;
+	for (i = 0; i < length; i++) {
+		unsigned long v;
+
+		v = ptr[i];
+		if (i & 1)
+			v <<= 8;
+		/* Add the new value */
+		sum += v;
+		/* Wrap around the carry */
+		if (sum > 0xffff)
+			sum = (sum + (sum >> 16)) & 0xffff;
+	}
+	value.byte[0] = sum & 0xff;
+	value.byte[1] = (sum >> 8) & 0xff;
+	return (~value.word) & 0xffff;
+}
+
+unsigned long add_ip_checksums(unsigned long offset, unsigned long sum,
+			       unsigned long new)
+{
+	unsigned long checksum;
+
+	sum = ~sum & 0xffff;
+	new = ~new & 0xffff;
+	if (offset & 1) {
+		/*
+		 * byte-swap the sum if it came from an odd offset; since the
+		 * computation is endian independant this works.
+		 */
+		new = ((new >> 8) & 0xff) | ((new << 8) & 0xff00);
+	}
+	checksum = sum + new;
+	if (checksum > 0xffff)
+		checksum -= 0xffff;
+
+	return (~checksum) & 0xffff;
+}
diff --git a/arch/x86/include/asm/ip_checksum.h b/arch/x86/include/asm/ip_checksum.h
new file mode 100644
index 0000000..6553d7b
--- /dev/null
+++ b/arch/x86/include/asm/ip_checksum.h
@@ -0,0 +1,16 @@
+/*
+ * From Coreboot ip_checksum.h
+ *
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#ifndef _IP_CHECKSUM_H
+#define _IP_CHECKSUM_H
+
+unsigned long compute_ip_checksum(void *addr, unsigned long length);
+unsigned long add_ip_checksums(unsigned long offset, unsigned long sum,
+			       unsigned long new);
+
+#endif /* IP_CHECKSUM_H */
-- 
2.2.0.rc0.207.ga3a616c