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

[Bin Meng]

Hi Simon,

On Tue, Dec 30, 2014 at 9:12 AM, Simon Glass <sjg at chromium.org> wrote:
> Add a checksum implementation that can be used with CMOS RAM.

What about the existing coreboot version of checksum implementation
(arch/x86/cpu/coreboot/ipchecksum.c)? We need consolidate them.

> 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

The name of ip_checksum.c is misleading. Maybe cmos_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)

compute_cmos_checksum?

> +{
> +       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)

add_cmos_checksums?

> +{
> +       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 */
> --

Regards,
Bin