[PATCH 2/4] dm: hash: Add new UCLASS_HASH support

[Simon Glass]

Hi,

On Thu, 16 Sept 2021 at 09:43, Alex G. <mr.nuke.me at gmail.com> wrote:
>
> Hi,
>
> On 7/29/21 8:08 PM, Chia-Wei Wang wrote:
> > Add UCLASS_HASH for hash driver development. Thus the
> > hash drivers (SW or HW-accelerated) can be developed
> > in the DM-based fashion.
>
> Software hashing implementations are shared tightly with host tools.
> With DM, there's no opportunity for code sharing with host tools. The
> design question that I have is "do we want to DM hashes, or do we want
> to DM hardware accelerators for hashes?"
>
> I did some parallel work expose remaining hash algos via
> hash_lookup_algo() and hash_progressive_lookup_algo().
>
> > Signed-off-by: Chia-Wei Wang <chiawei_wang at aspeedtech.com>
> > ---
> >   drivers/crypto/Kconfig            |   2 +
> >   drivers/crypto/Makefile           |   1 +
> >   drivers/crypto/hash/Kconfig       |   5 ++
> >   drivers/crypto/hash/Makefile      |   5 ++
> >   drivers/crypto/hash/hash-uclass.c | 121 ++++++++++++++++++++++++++++++
> >   include/dm/uclass-id.h            |   1 +
> >   include/u-boot/hash.h             |  61 +++++++++++++++
> >   7 files changed, 196 insertions(+)
> >   create mode 100644 drivers/crypto/hash/Kconfig
> >   create mode 100644 drivers/crypto/hash/Makefile
> >   create mode 100644 drivers/crypto/hash/hash-uclass.c
> >   create mode 100644 include/u-boot/hash.h
> >
> > diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
> > index 1ea116be75..0082177c21 100644
> > --- a/drivers/crypto/Kconfig
> > +++ b/drivers/crypto/Kconfig
> > @@ -1,5 +1,7 @@
> >   menu "Hardware crypto devices"
> >
> > +source drivers/crypto/hash/Kconfig
> > +
> Hashes are useful outside of cryptographic functions, so it seems odd to
> merge them in crypto. For example, CRC32 is not a hash useful in crypto,
> but otherwise widely used in u-boot.

Are you syching to move this to drivers/hash ? I feel that hashing is
close enough to crypto that it might not be worth having a new
'top-level' driver directory.

Some might say that md5 is in the same board (not useful for crypto)
but it used to be. Similarly, sha1 is fading away.

>
> [snip]
> > diff --git a/drivers/crypto/hash/hash-uclass.c b/drivers/crypto/hash/hash-uclass.c
> > new file mode 100644
> > index 0000000000..446eb9e56a
> > --- /dev/null
> > +++ b/drivers/crypto/hash/hash-uclass.c
> > @@ -0,0 +1,121 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (c) 2021 ASPEED Technology Inc.
> > + * Author: ChiaWei Wang <chiawei_wang at aspeedtech.com>
> > + */
> > +
> > +#define LOG_CATEGORY UCLASS_HASH
> > +
> > +#include <common.h>
> > +#include <dm.h>
> > +#include <asm/global_data.h>
> > +#include <u-boot/hash.h>
> > +#include <errno.h>
> > +#include <fdtdec.h>
> > +#include <malloc.h>
> > +#include <asm/io.h>
> > +#include <linux/list.h>
> > +
> > +struct hash_info {
> > +     char *name;
> > +     uint32_t digest_size;
> > +};
> > +
> > +static const struct hash_info hash_info[HASH_ALGO_NUM] = {
> > +     [HASH_ALGO_CRC16_CCITT] = { "crc16-ccitt", 2 },
> > +     [HASH_ALGO_CRC32] = { "crc32", 4 },
> > +     [HASH_ALGO_MD5] = { "md5", 16 },
> > +     [HASH_ALGO_SHA1] = { "sha1", 20 },
> > +     [HASH_ALGO_SHA256] = { "sha256", 32 },
> > +     [HASH_ALGO_SHA384] = { "sha384", 48 },
> > +     [HASH_ALGO_SHA512] = { "sha512", 64},
> > +};
>
> It seems a step backwards to have to enum {} our hash algos, since we
> already identify them by their strings (e.g. "sha256"). and then
> associated ops structure. The
>
> > +
> > +enum HASH_ALGO hash_algo_lookup_by_name(const char *name)
>
>      string -> hash_lookup_algo() -> ops struct
>
> Is the current way to do things. hash_algo_lookup_by_name() does the
> roundabout through an enum. That doesn't make sense to me.

Actually I'd like to see an enum to describe these, since looking up a
string is less efficient in a bootloader. So some way of doing that
seems good to me.

Of course it means we need a global list of this algos in a header
file and each driver needs to indicate which one(s) it supports.

Regards,
Simon