Re: [PATCH v2 10/10] ARM: i.MX8MP: skov: assign Ethernet addresses to all ports

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Oleksij,

On 02.10.23 12:16, Oleksij Rempel wrote:
> Assign Ethernet address to all ports based on the master address stored
> in the NVMEM. In case nothing nvmem is clean, generate address based on
> vendor OUI with part of i.MX8MP unique ID.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  arch/arm/boards/skov-imx8mp/board.c | 97 +++++++++++++++++++++++++++++
>  1 file changed, 97 insertions(+)
> 
> diff --git a/arch/arm/boards/skov-imx8mp/board.c b/arch/arm/boards/skov-imx8mp/board.c
> index 3b6eb7b080..6de9ab47ab 100644
> --- a/arch/arm/boards/skov-imx8mp/board.c
> +++ b/arch/arm/boards/skov-imx8mp/board.c
> @@ -12,13 +12,18 @@
>  #include <io.h>
>  #include <mach/imx/bbu.h>
>  #include <mach/imx/generic.h>
> +#include <mach/imx/imx8mq.h>
>  #include <mach/imx/iomux-mx8mp.h>
> +#include <net.h>
> +#include <of_net.h>
>  
>  struct skov_imx8mp_priv {
>  	struct device *dev;
>  	int variant_id;
>  };
>  
> +#define SKOV_OUI  {0x00, 0x0e, 0xcd}
> +
>  static struct skov_imx8mp_priv *skov_imx8mp_priv;
>  
>  #define GPIO_HW_VARIANT  {\
> @@ -85,6 +90,98 @@ static const struct board_description imx8mp_variants[] = {
>  	},
>  };
>  
> +static struct eth_device *
> +skov_imx8mp_init_master_edev(struct skov_imx8mp_priv *priv,
> +			     struct device_node *np)
> +{
> +	u8 oui_mac[ETH_ALEN] = SKOV_OUI;
> +	struct eth_device *edev;
> +
> +	edev = of_find_eth_device_by_node(np);
> +	if (!edev) {
> +		dev_err(priv->dev, "Failed to find master eth device\n");
> +		return NULL;
> +	}
> +
> +	if (is_valid_ether_addr(edev->ethaddr))
> +		return edev;
> +
> +	if (!edev->parent || of_get_mac_addr_nvmem(edev->parent->of_node,
> +						   oui_mac)) {
> +		char str[sizeof("xx:xx:xx:xx:xx:xx")];
> +		u64 unique_id;
> +
> +		unique_id = imx8m_uid();
> +		if (!unique_id)
> +			dev_err(priv->dev, "Failed to get i.MX8MP unique ID\n");
> +
> +		/* Generate MAC address based on i.MX8MP unique ID */
> +		oui_mac[3] = (unique_id >> 56) & 0xff;
> +		oui_mac[4] = (unique_id >> 48) & 0xff;
> +		oui_mac[5] = (unique_id >> 40) & 0xff;
> +		ethaddr_to_string(oui_mac, str);
> +		dev_warn(priv->dev, "Failed to get master eth addr. Generating based on i.MX8MP unique ID: %s\n",
> +			 str);

I attempted to solve this generically in [1]. I'd prefer to get that in instead of
board-specific measures. I also think that it might be a bad idea to expose the
unique ID like that as this allows easy brute forcing of the machine ID that's
generated by default out of the UID.

[1]: https://lore.barebox.org/barebox/20230911155927.3786335-1-a.fatoum@pengutronix.de/

> +	}
> +
> +	of_eth_register_ethaddr(np, oui_mac);
> +
> +	return edev;
> +}
> +
> +static void skov_imx8mp_register_ethaddr(struct skov_imx8mp_priv *priv,
> +					 struct device_node *root)
> +{
> +	struct eth_device *master_edev;
> +	struct eth_node_info {
> +		const char *alias;
> +		struct device_node *np;
> +		u32 inc;
> +	} eth_nodes[] = {
> +		{ "ethernet0", NULL, 0 },
> +		/* Addresses are assigned in the reverse order
> +		 * LAN2 addr < LAN1 addr
> +		 */
> +		{ "ethernet1", NULL, 1 },
> +		{ "ethernet2", NULL, 0 },
> +	};
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(eth_nodes); i++) {
> +		eth_nodes[i].np = of_find_node_by_alias(root,
> +							eth_nodes[i].alias);
> +		if (!eth_nodes[i].np) {
> +			dev_err(priv->dev, "Failed to find %s alias\n",
> +				eth_nodes[i].alias);
> +			return;
> +		}
> +	}
> +
> +	master_edev = skov_imx8mp_init_master_edev(priv, eth_nodes[0].np);
> +	if (!master_edev) {
> +		dev_err(priv->dev, "Failed to init master edev\n");
> +		return;
> +	}
> +
> +	/* Set ETH addresses for all but master edev */
> +	for (i = 1; i < ARRAY_SIZE(eth_nodes); i++) {
> +		u8 ethaddr[ETH_ALEN];
> +
> +		ether_addr_inc(ethaddr, master_edev->ethaddr, eth_nodes[i].inc);
> +		of_eth_register_ethaddr(eth_nodes[i].np, ethaddr);
> +	}
> +}
> +
> +static int skov_imx8mp_populate_ethaddr(void)
> +{
> +	struct skov_imx8mp_priv *priv = skov_imx8mp_priv;
> +
> +	skov_imx8mp_register_ethaddr(priv, NULL);
> +
> +	return 0;
> +}
> +postenvironment_initcall(skov_imx8mp_populate_ethaddr);
> +
>  static int skov_imx8mp_fixup(struct device_node *root, void *data)
>  {
>  	struct device_node *chosen = of_create_node(root, "/chosen");

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