[PATCH 1/2] arm64: imx8mp: Read MAC address from M24C32-D write-lockable page on DH i.MX8MP DHCOM if available

[Marek Vasut]

On 10/16/24 1:57 PM, Christoph Niedermaier wrote:
> From: Marek Vasut <marex at denx.de>
> Sent: Saturday, October 12, 2024 10:43 PM
>> On 10/10/24 3:23 PM, Christoph Niedermaier wrote:
>>> The i.MX8M Plus DHCOM currently supports parsing ethernet MAC address
>>> from multiple sources in the following priority order:
>>>
>>> 1) U-Boot environment 'ethaddr'/'eth1addr' environment variable
>>> 2) SoC OTP fuses
>>> 3) On-SoM EEPROM
>>>
>>> The new i.MX8M Plus DHCOM rev.200 is populated with M24C32-D EEPROM
>>> which contains additional write-lockable page, which can also be
>>> populated with a structure containing ethernet MAC address.
>>>
>>> Add support for parsing the content of this new write-lockable page
>>> and place it between 2) and 3) on the priority list. The new entry is
>>> 2.5) On-SoM EEPROM write-lockable page
>>>
>>> Because the write-lockable page is not present on rev.100 i.MX8MP DHCOM
>>> SoM, test whether EEPROM ID page exists in DT and whether it is enabled
>>> first. If so, read the entire ID page out, validate it, and determine
>>> whether EEPROM MAC address is populated in it in DH specific format. If
>>> so, use the MAC address. There may be multiple EEPROMs with an ID page
>>> on this platform, always use the first one.
>>>
>>> Signed-off-by: Christoph Niedermaier <cniedermaier at dh-electronics.com>
>>> ---
>>> Cc: "NXP i.MX U-Boot Team" <uboot-imx at nxp.com>
>>> Cc: Marek Vasut <marex at denx.de>
>>> Cc: Fabio Estevam <festevam at gmail.com>
>>> Cc: Stefano Babic <sbabic at denx.de>
>>> Cc: Tom Rini <trini at konsulko.com>
>>> Cc: u-boot at dh-electronics.com
>>> ---
>>>    board/dhelectronics/common/dh_common.c        | 113 ++++++++++++++++++
>>>    board/dhelectronics/common/dh_common.h        |  23 ++++
>>>    .../dh_imx8mp/imx8mp_dhcom_pdk2.c             |   6 +
>>>    3 files changed, 142 insertions(+)
>>>
>>> diff --git a/board/dhelectronics/common/dh_common.c b/board/dhelectronics/common/dh_common.c
>>> index 32c50b4f0f..8ea70fc984 100644
>>> --- a/board/dhelectronics/common/dh_common.c
>>> +++ b/board/dhelectronics/common/dh_common.c
>>> @@ -7,9 +7,22 @@
>>>    #include <dm.h>
>>>    #include <i2c_eeprom.h>
>>>    #include <net.h>
>>> +#include <u-boot/crc.h>
>>>
>>>    #include "dh_common.h"
>>>
>>> +struct eeprom_id_page {
>>> +     u8      id[3];          /* Identifier 'D', 'H', 'E' - 'D' is at index 0 */
>>> +     u8      version;        /* 0x10 -- Version 1.0 */
>>> +     u8      data_crc16[2];  /* [1] is MSbyte */
>>> +     u8      header_crc8;
>>> +     u8      mac0[6];
>>> +     u8      mac1[6];
>>> +     u8      item_prefix;    /* H/F is coded in MSbits, Vendor coding starts at LSbits */
>>> +     u8      item_num[3];    /* [2] is MSbyte */
>>> +     u8      serial[9];      /* [8] is MSbyte */
>>> +} __packed;
>>
>> Is __packed needed ?
> 
> I want to avoid padding in any case.
Every single field is u8, do you observe any padding ?