Date:   Fri, 14 Feb 2020 16:57:30 -0300
From:   Paul Cercueil <paul@...pouillou.net>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Discussions about the Letux Kernel <letux-kernel@...nphoenux.org>,
        Andrew Lunn <andrew@...n.ch>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Richard Fontana <rfontana@...hat.com>,
        kernel@...a-handheld.com,
        Petr Štetiar <ynezz@...e.cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        Heiner Kallweit <hkallweit1@...il.com>
Subject: Re: [Letux-kernel] [PATCH v2] net: davicom: dm9000: allow to pass MAC
 address through mac_addr module parameter



Le ven., févr. 14, 2020 at 20:38, H. Nikolaus Schaller 
<hns@...delico.com> a écrit :
>>  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.
>> 

Yes, I think it's a bit too complex - it's probably fine to just read 
chunks of 4 bytes.

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

Yes, a proper fix usually means more work ;)
>> 
>>  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?

In the dm9000's devicetree node you'd have a "mac-address = 
<&mac_addr>;". The "mac-address" is already a standard property, and 
the davicom driver already supports it.

The "mac_addr" should be a pointer to the efuse cell that corresponds 
to the MAC address. See the examples at the bottom of 
Documentation/devicetree/bindings/nvmem/nvmem.yaml and 
Documentation/devicetree/bindings/nvmem/nvmem-consumer.yaml.

-Paul

> 
>> 
>>  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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