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

[Paul Cercueil]

Le ven., févr. 14, 2020 at 20:38, H. Nikolaus Schaller 
<hns@xxxxxxxxxxxxx> a écrit :
> >  Am 14.02.2020 um 20:24 schrieb H. Nikolaus Schaller 
> > <hns@xxxxxxxxxxxxx>:
> >
> >
> > >  Am 14.02.2020 um 19:47 schrieb Paul Cercueil 
> > > <paul@xxxxxxxxxxxxxxx>:
> > >
> > >  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@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
> > > >  ---
> > > >  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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