Subject: Re: [PATCH v2] net: davicom: dm9000: allow to pass MAC address through mac_addr module parameter

From: Paul Cercueil <[email-masked]>
Date: Fri, 14 Feb 2020 15:47:28 -0300

Hi Nikolaus,

What I'd suggest is to write a NVMEM driver for the efuse and retrieve 
the MAC address cleanly with nvmem_get_mac_address().

It shouldn't be hard to do (there's already code for it in the 
non-upstream 3.18 kernel for the CI20) and you remove the dependency on 
uboot.

-Paul

Le ven., févr. 14, 2020 at 17:07, H. Nikolaus Schaller 
<[email-masked]> a écrit :
> The MIPS Ingenic CI20 board is shipped with a quite old u-boot
> (ci20-v2013.10 see https://elinux.org/CI20_Dev_Zone). This passes
> the MAC address through dm9000.mac_addr=xx:xx:xx:xx:xx:xx
> kernel module parameter to give the board a fixed MAC address.
> 
> This is not processed by the dm9000 driver which assigns a random
> MAC address on each boot, making DHCP assign a new IP address
> each time.
> 
> So we add a check for the mac_addr module parameter as a last
> resort before assigning a random one. This mechanism can also
> be used outside of u-boot to provide a value through modprobe
> config.
> 
> To parse the MAC address in a new function get_mac_addr() we
> use an copy adapted from the ksz884x.c driver which provides
> the same functionality.
> 
> Signed-off-by: H. Nikolaus Schaller <[email-masked]>
> ---
>  drivers/net/ethernet/davicom/dm9000.c | 42 
> +++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/drivers/net/ethernet/davicom/dm9000.c 
> b/drivers/net/ethernet/davicom/dm9000.c
> index 1ea3372775e6..7402030b0352 100644
> --- a/drivers/net/ethernet/davicom/dm9000.c
> +++ b/drivers/net/ethernet/davicom/dm9000.c
> @@ -1409,6 +1409,43 @@ static struct dm9000_plat_data 
> *dm9000_parse_dt(struct device *dev)
>  	return pdata;
>  }
> 
> +static char *mac_addr = ":";
> +module_param(mac_addr, charp, 0);
> +MODULE_PARM_DESC(mac_addr, "MAC address");
> +
> +static void get_mac_addr(struct net_device *ndev, char *macaddr)
> +{
> +	int i = 0;
> +	int j = 0;
> +	int got_num = 0;
> +	int num = 0;
> +
> +	while (j < ETH_ALEN) {
> +		if (macaddr[i]) {
> +			int digit;
> +
> +			got_num = 1;
> +			digit = hex_to_bin(macaddr[i]);
> +			if (digit >= 0)
> +				num = num * 16 + digit;
> +			else if (':' == macaddr[i])
> +				got_num = 2;
> +			else
> +				break;
> +		} else if (got_num) {
> +			got_num = 2;
> +		} else {
> +			break;
> +		}
> +		if (got_num == 2) {
> +			ndev->dev_addr[j++] = (u8)num;
> +			num = 0;
> +			got_num = 0;
> +		}
> +		i++;
> +	}
> +}
> +
>  /*
>   * Search DM9000 board, allocate space and register it
>   */
> @@ -1679,6 +1716,11 @@ dm9000_probe(struct platform_device *pdev)
>  			ndev->dev_addr[i] = ior(db, i+DM9000_PAR);
>  	}
> 
> +	if (!is_valid_ether_addr(ndev->dev_addr)) {
> +		mac_src = "param";
> +		get_mac_addr(ndev, mac_addr);
> +	}
> +
>  	if (!is_valid_ether_addr(ndev->dev_addr)) {
>  		inv_mac_addr = true;
>  		eth_hw_addr_random(ndev);
> --
> 2.23.0
>