linux-kernel - Re: [PATCH 6/6] nvmem: u-boot-env: post process "ethaddr" env variable

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Message-ID: <6b30d7ae-ea99-61ba-6d41-15d1a5de7729@gmail.com>
Date:   Tue, 10 Jan 2023 13:41:36 +0100
From:   Rafał Miłecki <zajec5@...il.com>
To:     Michael Walle <michael@...le.cc>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, u-boot@...ts.denx.de,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH 6/6] nvmem: u-boot-env: post process "ethaddr" env
 variable

On 10.01.2023 13:19, Michael Walle wrote:
> Hi,
> 
> Am 2023-01-10 11:54, schrieb Rafał Miłecki:
>> From: Rafał Miłecki <rafal@...ecki.pl>
>>
>> U-Boot environment variables are stored in ASCII format so "ethaddr"
>> requires parsing into binary to make it work with Ethernet interfaces.
>>
>> This includes support for indexes to support #nvmem-cell-cells = <1>.
>>
>> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
>> ---
>>  drivers/nvmem/layouts/Kconfig      |  1 +
>>  drivers/nvmem/layouts/u-boot-env.c | 24 ++++++++++++++++++++++++
>>  2 files changed, 25 insertions(+)
>>
>> diff --git a/drivers/nvmem/layouts/Kconfig b/drivers/nvmem/layouts/Kconfig
>> index 8a38c514943a..566b4f25630d 100644
>> --- a/drivers/nvmem/layouts/Kconfig
>> +++ b/drivers/nvmem/layouts/Kconfig
>> @@ -23,6 +23,7 @@ config NVMEM_LAYOUT_ONIE_TLV
>>  config NVMEM_LAYOUT_U_BOOT_ENV
>>      bool "U-Boot environment variables support"
>>      select CRC32
>> +    select GENERIC_NET_UTILS
>>      help
>>        U-Boot stores its setup as environment variables. This driver adds
>>        support for verifying & exporting such data. It also exposes variables
>> diff --git a/drivers/nvmem/layouts/u-boot-env.c
>> b/drivers/nvmem/layouts/u-boot-env.c
>> index 95c314553952..63baeb18bd56 100644
>> --- a/drivers/nvmem/layouts/u-boot-env.c
>> +++ b/drivers/nvmem/layouts/u-boot-env.c
>> @@ -4,6 +4,8 @@
>>   */
>>
>>  #include <linux/crc32.h>
>> +#include <linux/etherdevice.h>
>> +#include <linux/if_ether.h>
>>  #include <linux/mod_devicetable.h>
>>  #include <linux/module.h>
>>  #include <linux/nvmem-consumer.h>
>> @@ -36,6 +38,26 @@ struct u_boot_env_image_broadcom {
>>      uint8_t data[];
>>  } __packed;
>>
>> +static int u_boot_env_read_post_process_ethaddr(void *context, const
>> char *id, int index,
>> +                        unsigned int offset, void *data, size_t *bytes)
>> +{
>> +    u8 mac[ETH_ALEN];
>> +
>> +    if (*bytes != 3 * ETH_ALEN - 1)
>> +        return -EINVAL;
>> +
>> +    if (!mac_pton(data, mac))
>> +        return -EINVAL;
>> +
>> +    if (index)
>> +        eth_addr_add(mac, index);
>> +
>> +    ether_addr_copy(data, mac);
>> +    *bytes = ETH_ALEN;
> 
> I don't know how to feel about this. This will only work if the new
> size is smaller than the old one. Can't we have a correct size in
> the first place? I.e. while adding the cells.

I didn't think about such solution. I like that idea. Will do.