[PATCH 1/3] net: Add a CONFIG_NET_BOARD_ETHADDR

[Marek Vasut]

On 3/14/24 3:43 PM, Detlev Casanova wrote:
> On some boards, a MAC address is set based on the CPU ID or other
> information. This is usually done in the misc_init_r() function.
> 
> This becomes a problem for net devices that are probed after the call to
> misc_init_r(), for example, when the ethernet is on a PCI port, which
> needs to be enumerated.
> 
> In this case, misc_init_r() will set the ethaddr variable, then, when
> the ethernet device is probed, if it has a ROM address, u-boot will warn
> about a MAC address mismatch and use the misc_init_r() address instead
> of the one in ROM.
> 
> The operating system later will most likely use the ROM MAC address,
> which can be confusing.
> 
> To avoid that, this commit introduces a CONFIG_NET_BOARD_ETHADDR that
> allows board files to implement a function to set an ethaddr in the
> environment, that will only be called when necessary. The logic is now:
> 
> - If there is there an ethaddr env var, use it.
> - If not, if there is a DT MAC address, use it.
> - If not, if there is a ROM MAC address, use it.
> - If not, if CONFIG_NET_BOARD_ETHADDR, call board_gen_ethaddr() and use
>    it.
> - If not, if CONFIG_NET_RANDOM_ETHADDR, generate random MAC
> - If not, fail with No valid MAC address found
> 
> Signed-off-by: Detlev Casanova <detlev.casanova at collabora.com>
> ---
>   net/Kconfig      |  7 +++++++
>   net/eth-uclass.c | 17 +++++++++++++++--
>   2 files changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/net/Kconfig b/net/Kconfig
> index 5dff6336293..6dd333ddb9e 100644
> --- a/net/Kconfig
> +++ b/net/Kconfig
> @@ -54,6 +54,13 @@ config NET_RANDOM_ETHADDR
>   	  generated. It will be saved to the appropriate environment variable,
>   	  too.
>   
> +config NET_BOARD_ETHADDR
> +	bool "Board specific ethaddr if unset"
> +	help
> +	  Allow a board function to set a specific Ethernet address that can
> +	  be, e.g., based on the CPU ID. If set, this will be tried before
> +	  setting a random address (if set).
> +
>   config NETCONSOLE
>   	bool "NetConsole support"
>   	help
> diff --git a/net/eth-uclass.c b/net/eth-uclass.c
> index 3d0ec91dfa4..f194df8512a 100644
> --- a/net/eth-uclass.c
> +++ b/net/eth-uclass.c
> @@ -56,6 +56,12 @@ __weak int board_interface_eth_init(struct udevice *dev,
>   	return 0;
>   }
>   
> +/* board-specific MAC Address generation. */
> +__weak int board_gen_ethaddr(int dev_num, u8 *mac_addr)
> +{
> +	return 0;
> +}
> +
>   static struct eth_uclass_priv *eth_get_uclass_priv(void)
>   {
>   	struct uclass *uc;
> @@ -563,13 +569,20 @@ static int eth_post_probe(struct udevice *dev)
>   	if (!eth_dev_get_mac_address(dev, pdata->enetaddr) ||
>   	    !is_valid_ethaddr(pdata->enetaddr)) {
>   		/* Check if the device has a MAC address in ROM */
> +		int ret = -1;
>   		if (eth_get_ops(dev)->read_rom_hwaddr) {
> -			int ret;
> -
>   			ret = eth_get_ops(dev)->read_rom_hwaddr(dev);
>   			if (!ret)
>   				source = "ROM";
>   		}
> +		if (IS_ENABLED(CONFIG_NET_BOARD_ETHADDR) && ret) {
> +			board_gen_ethaddr(dev_seq(dev), pdata->enetaddr);

You do need to pass in the udevice *dev directly, otherwise this DM 
uclass patch would behave like non-DM code.

I'd personally just create a __weak board_gen_ethaddr() function here 
and let boards override it, without new Kconfig symbol.