netdev - Re: [PATCH v2] net: davicom: dm9000: allow to pass MAC address through mac

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Message-Id: <996F2206-B261-46E3-9167-B48BA7D3C9FF@goldelico.com>
Date:   Fri, 14 Feb 2020 20:24:22 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Andrew Lunn <andrew@...n.ch>,
        "David S. Miller" <davem@...emloft.net>,
        Petr Štetiar <ynezz@...e.cz>,
        Richard Fontana <rfontana@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Heiner Kallweit <hkallweit1@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, letux-kernel@...nphoenux.org,
        kernel@...a-handheld.com
Subject: Re: [PATCH v2] net: davicom: dm9000: allow to pass MAC address through mac_addr module parameter


> Am 14.02.2020 um 19:47 schrieb Paul Cercueil <paul@...pouillou.net>:
> 
> 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.

Interesting approach. I have found this:

https://lore.kernel.org/patchwork/patch/868158/

but it looks as if it was never finished (I could not locate a V3 or anything mainline?)
and and it tries to solve other problems as well.

And it looks to be much more complex than my "solution" to the immediate problem.

I have to study it to know if I can write a nvmem_get_mac_address().

BR,
Nikolaus

> 
> -Paul
> 
> 
> Le ven., févr. 14, 2020 at 17:07, H. Nikolaus Schaller <hns@...delico.com> 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 <hns@...delico.com>
>> ---
>> 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
> 
>