Am 2021-12-29 19:18, schrieb Jakub Kicinski:
On Wed, 29 Dec 2021 13:40:47 +0100 Michael Walle wrote:
> Some NVMEM devices have text based cells. In such cases MAC is stored in
> a XX:XX:XX:XX:XX:XX format. Use mac_pton() to parse such data and
> support those NVMEM cells. This is required to support e.g. a very
> popular U-Boot and its environment variables.
>
> Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx>
> ---
> Please let me know if checking NVMEM cell length (6 B vs. 17 B) can be
> considered a good enough solution. Alternatively we could use some DT
> property to make it explicity, e.g. something like:
>
> ethernet@18024000 {
> compatible = "brcm,amac";
> reg = <0x18024000 0x800>;
>
> nvmem-cells = <&mac_addr>;
> nvmem-cell-names = "mac-address";
> nvmem-mac-format = "text";
> };
Please note, that there is also this proposal, which had such a
conversion
in mind:
https://lore.kernel.org/linux-devicetree/20211228142549.1275412-1-michael@xxxxxxxx/
With this patch, there are now two different places where a mac
address
format is converted. In of_get_mac_addr_nvmem() and in the imx otp
driver.
And both have their shortcomings and aren't really flexible. Eg. this
one
magically detects the format by comparing the length, but can't be
used for
to swap bytes (because the length is also ETH_ALEN), which apparently
is a
use case in the imx otp driver. And having the conversion in an nvmem
provider device driver is still a bad thing IMHO.
I'd really like to see all these kind of transformations in one place.
FWIW offsetting from a common base address is relatively common, that's
why we have:
/**
* eth_hw_addr_gen - Generate and assign Ethernet address to a port
* @dev: pointer to port's net_device structure
* @base_addr: base Ethernet address
* @id: offset to add to the base address
*
* Generate a MAC address using a base address and an offset and assign
it
* to a net_device. Commonly used by switch drivers which need to
compute
* addresses for all their ports. addr_assign_type is not changed.
*/
static inline void eth_hw_addr_gen(struct net_device *dev, const u8
*base_addr,
unsigned int id)
I didn't know that. But it doesn't help me that much because it mostly
used for switches, but in my case, I also have up to four network
cards (enetc) on the SoC; besides a network switch (felix). But
only one source for the base mac address.
-michael
