netdev - Re: [Letux-kernel] [PATCH v2] net: davicom: dm9000: allow to pass MAC address through mac_addr module parameter

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Date:   Fri, 14 Feb 2020 21:05:18 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Andrew Lunn <andrew@...n.ch>, netdev <netdev@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Richard Fontana <rfontana@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>, kernel@...a-handheld.com,
        Petr Štetiar <ynezz@...e.cz>,
        "David S. Miller" <davem@...emloft.net>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>
Subject: Re: [Letux-kernel] [PATCH v2] net: davicom: dm9000: allow to pass MAC address through mac_addr module parameter

> Am 14.02.2020 um 20:38 schrieb H. Nikolaus Schaller <hns@...delico.com>:
> 
> 
>> Am 14.02.2020 um 20:24 schrieb H. Nikolaus Schaller <hns@...delico.com>:
>> 
>> 
>>> 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().
> 
> Another question is how to link this very jz4780 specific code to the generic davicom dm9000 driver?
> And where should the new code live. In some jz4780 specific file or elsewhere?

Ok, got it.

nvmem_get_mac_address() is looking for a nvmem cell "mac-address".

So some jz4780 specific driver must provide such cells.

There aren't many examples but it appears as if arch/arm/mach-davinci/board-da830-evm.c
defines and registers nvmem cells.

But maybe it is not difficult to teach the 2018 driver to provide such cells.

BR and thanks,
Nikolaus

> 
>> 
>> 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
>>> 
>>> 
>> 
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> 
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