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

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Message-ID: <c4cc5b274745fe9dcb83747e74879582@walle.cc>
Date:   Tue, 10 Jan 2023 13:19:09 +0100
From:   Michael Walle <michael@...le.cc>
To:     Rafał Miłecki <zajec5@...il.com>
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

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.

-michael

> +
> +	return 0;
> +}
> +
>  static int u_boot_env_parse_data(struct device *dev, struct
> nvmem_device *nvmem, uint8_t *buf,
>  				 size_t data_offset, size_t data_len)
>  {
> @@ -67,6 +89,8 @@ static int u_boot_env_parse_data(struct device *dev,
> struct nvmem_device *nvmem,
>  		info.offset = data_offset + value - data;
>  		info.bytes = strlen(value);
>  		info.np = of_get_child_by_name(np, info.name);
> +		if (!strcmp(var, "ethaddr"))
> +			info.read_post_process = u_boot_env_read_post_process_ethaddr;
> 
>  		err = nvmem_add_one_cell(nvmem, &info);
>  		if (err) {