[U-Boot] [PATCH 09/14] net: Add ability to set MAC address via EEPROM
Joe Hershberger
joe.hershberger at gmail.com
Wed Nov 30 20:52:32 CET 2016
On Wed, Nov 30, 2016 at 2:10 AM, Olliver Schinagl <oliver at schinagl.nl> wrote:
> Hey Michal,
>
>
>
> On 29-11-16 19:54, Michal Simek wrote:
>>
>> On 29.11.2016 17:45, Olliver Schinagl wrote:
>>>
>>> Hey Michal,
>>>
>>>
>>> On 28-11-16 09:21, Michal Simek wrote:
>>>>
>>>> On 25.11.2016 16:30, Olliver Schinagl wrote:
>>>>>
>>>>> This patch allows Kconfig to enable and set parameters to make it
>>>>> possible to read the MAC address from an EEPROM. The net core layer
>>>>> then
>>>>> uses this information to read MAC addresses from this EEPROM.
>>>>>
>>>>> Besides the various tuneables as to how to access the eeprom (bus,
>>>>> address, addressing mode/length, 2 configurable that are EEPROM generic
>>>>> (e.g. SPI or some other form of access) which are:
>>>>>
>>>>> NET_ETHADDR_EEPROM_OFFSET, indicating where in the EEPROM the start of
>>>>> the MAC address is. The default is 8 allowing for 8 bytes before the
>>>>> MAC
>>>>> for other purposes (header MAGIC for example).
>>>>>
>>>>> NET_ETHADDR_EEPROM_CRC8, indicating the MAC is appended with a
>>>>> CRC8-CCIT
>>>>> checksum that should be verified.
>>>>>
>>>>> Currently only I2C eeproms have been tested and thus only those options
>>>>> are available, but shouldn't be a limit. NET_ETHADDR_EEPROM_SPI can be
>>>>> just as created and added.
>>>>>
>>>>> The code currently first checks if there is a non-zero MAC address in
>>>>> the eeprom. If that fails to be the case, the read_rom_hwaddr can be
>>>>> used by a board to supply the MAC in other ways.
>>>>>
>>>>> If both these fails, the other code is still in place to query the
>>>>> environent, which then can be used to override the hardware supplied
>>>>> data.
>>>>>
>>>>> Signed-off-by: Olliver Schinagl <oliver at schinagl.nl>
>>>>> ---
>>>>> doc/README.enetaddr | 99
>>>>> +++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>>> include/net.h | 14 ++++++++
>>>>> net/Kconfig | 59 +++++++++++++++++++++++++++++++
>>>>> net/eth-uclass.c | 9 +++--
>>>>> net/eth_common.c | 34 ++++++++++++++++++
>>>>> net/eth_legacy.c | 2 ++
>>>>> 6 files changed, 214 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/doc/README.enetaddr b/doc/README.enetaddr
>>>>> index 50e4899..89c1f7d 100644
>>>>> --- a/doc/README.enetaddr
>>>>> +++ b/doc/README.enetaddr
>>>>> @@ -47,6 +47,105 @@ Correct flow of setting up the MAC address
>>>>> (summarized):
>>>>> Previous behavior had the MAC address always being programmed into
>>>>> hardware
>>>>> in the device's init() function.
>>>>> +--------
>>>>> + EEPROM
>>>>> +--------
>>>>> +
>>>>> +Boards may come with an EEPROM specifically to store configuration
>>>>> bits, such
>>>>> +as a MAC address. Using CONFIG_NET_ETHADDR_EEPROM enables this
>>>>> feature.
>>>>> +Depending on the board, the EEPROM may be connected on various
>>>>> methods, but
>>>>> +currently, only the I2C bus can be used via
>>>>> CONFIG_NET_ETHADDR_EEPROM_I2C.
>>>>> +
>>>>> +The following config options are available,
>>>>> +CONFIG_NET_ETHADDR_EEPROM_I2C_BUS is the I2C bus on which the eeprom
>>>>> is present.
>>>>> +CONFIG_NET_ETHADDR_EEPROM_I2C_ADDR sets the address of the EEPROM,
>>>>> which
>>>>> +defaults to the very common 0x50. Small size EEPROM's generally use
>>>>> single byte
>>>>> +addressing but larger EEPROM's may use double byte addressing, which
>>>>> can be
>>>>> +configured using CONFIG_NET_ETHADDR_EEPROM_ADDRLEN.
>>>>> +
>>>>> +Within the EEPROM, the MAC address can be stored on any arbitrary
>>>>> offset,
>>>>> +CONFIG_NET_ETHADDR_EEPROM_OFFSET sets this to 8 as a default
>>>>> however, allowing
>>>>> +the first 8 bytes to be used for an optional data, for example a
>>>>> configuration
>>>>> +struct where the mac address is part of.
>>>>> +
>>>>> +Appending the 6 (ARP_HLEN) bytes is a CRC8 byte over the previous
>>>>> ARP_HLEN
>>>>> +bytes. Whether to check this CRC8 or not is dependent on
>>>>> +CONFIG_NET_ETHADDR_EEPROM_CRC8.
>>>>> +
>>>>> +To keep things nicely aligned, a final 'reserved' byte is added to
>>>>> the mac
>>>>> +address + crc8 combo.
>>>>> +
>>>>> +A board may want to store more information in its eeprom, using the
>>>>> following
>>>>> +example layout, this can be achieved.
>>>>> +
>>>>> +struct mac_addr {
>>>>> + uint8_t mac[ARP_HLEN];
>>>>> + uint8_t crc8;
>>>>> + uint8_t reserved;
>>>>> +};
>>>>> +
>>>>> +struct config_eeprom {
>>>>> + uint32_t magic;
>>>>> + uint8_t version;
>>>>> + uint8_t reserved[2];
>>>>> + uint8_t mac_cnt;
>>>>> + struct mac_addr[mac_cnt];
>>>>> +};
>>>>> +
>>>>> +Filling this in:
>>>>> +struct config_eeprom eeprom = {
>>>>> + .magic = { 'M', 'g', 'i', 'c' },
>>>>> + .reserved = { 0x00, 0x00 },
>>>>> + .mac_cnt = 2,
>>>>> + .mac_addr = {
>>>>> + {
>>>>> + .mac = {
>>>>> + 0x01, 0x23, 0x45,
>>>>> + 0x67, 0x89, 0xab,
>>>>> + },
>>>>> + .crc8 = 0xbe,
>>>>> + .reserved = 0x00,
>>>>> + }, {
>>>>> + .mac = {
>>>>> + 0xba, 0x98, 0x76,
>>>>> + 0x54, 0x32, 0x10,
>>>>> + },
>>>>> + .crc8 = 0x82,
>>>>> + .reserved = 0x00,
>>>>> + },
>>>>> + },
>>>>> +};
>>>>> +
>>>>> +The eeprom content would look like this.
>>>>> +
>>>>> +00000000 4d 67 69 63 01 00 00 02 01 23 45 67 89 ab be 00
>>>>> |Mgic.....#Eg....|
>>>>> +00000010 ba 98 76 54 32 10 82 00 |..vT2...|
>>>>> +
>>>>> +This can be done from linux using the i2c-tools:
>>>>> +
>>>>> +i2cset I2CBUS 0x50 0x08 0x01
>>>>> +i2cset I2CBUS 0x50 0x09 0x23
>>>>> +i2cset I2CBUS 0x50 0x0a 0x45
>>>>> +i2cset I2CBUS 0x50 0x0b 0x67
>>>>> +i2cset I2CBUS 0x50 0x0c 0x89
>>>>> +i2cset I2CBUS 0x50 0x0d 0xab
>>>>> +i2cset I2CBUS 0x50 0x0e 0xbe
>>>>> +
>>>>> +Alternativly this can be done from the u-boot console as:
>>>>> +
>>>>> +u-boot> mm.b 0
>>>>> +00000000: 00 ? 01
>>>>> +00000001: 23 ? 23
>>>>> +00000002: 45 ? 45
>>>>> +00000003: 67 ? 67
>>>>> +00000004: 89 ? 89
>>>>> +00000005: ab ? ab
>>>>> +00000006: be ? be
>>>>> +00000007: 00 ? q
>>>>> +i2c dev I2CBUS
>>>>> +i2c write 0 50 8 7
>>>>> +i2c md 50 8
>>>>> +
>>>>> -------
>>>>> Usage
>>>>> -------
>>>>> diff --git a/include/net.h b/include/net.h
>>>>> index 08f8af8..e50ab5d 100644
>>>>> --- a/include/net.h
>>>>> +++ b/include/net.h
>>>>> @@ -248,6 +248,20 @@ int eth_getenv_enetaddr(const char *name, uchar
>>>>> *enetaddr);
>>>>> int eth_setenv_enetaddr(const char *name, const uchar *enetaddr);
>>>>> /**
>>>>> + * eeprom_read_enetaddr() - Read the hardware address from an eeprom
>>>>> + *
>>>>> + * This function tries to read the MAC address from an eeprom as can
>>>>> be read
>>>>> + * in docs/README.enetaddr.
>>>>> + *
>>>>> + * @index: index of the interface to get the hwaddr for
>>>>> + * @enetaddr: pointer for the found hwaddr. Needs to be atleast
>>>>> ARP_HLEN
>>>>> + * @return: 0 on success, non-zero is error status. Additionally
>>>>> hwaddr
>>>>> + * is set to 00:00:00:00:00. This is also the case if
>>>>> + * CONFIG_NET_ETHADDR_EEPROM is not set.
>>>>> + */
>>>>> +int eeprom_read_enetaddr(const int index, unsigned char *enetaddr);
>>>>> +
>>>>> +/**
>>>>> * eth_setenv_enetaddr_by_index() - set the MAC address environment
>>>>> variable
>>>>> *
>>>>> * This sets up an environment variable with the given MAC address
>>>>> (@enetaddr).
>>>>> diff --git a/net/Kconfig b/net/Kconfig
>>>>> index 414c549..f699e1c 100644
>>>>> --- a/net/Kconfig
>>>>> +++ b/net/Kconfig
>>>>> @@ -7,6 +7,65 @@ menuconfig NET
>>>>> if NET
>>>>> +config NET_ETHADDR_EEPROM
>>>>> + bool "Get ethaddr from eeprom"
>>>>> + help
>>>>> + Selecting this will try to get the Ethernet address from an
>>>>> onboard
>>>>> + EEPROM and set into the environment if and only if the
>>>>> environment
>>>>> + does currently not already hold a MAC address. For more
>>>>> information
>>>>> + see doc/README.enetaddr.
>>>>> +
>>>>> +config NET_ETHADDR_EEPROM_I2C
>>>>> + depends on NET_ETHADDR_EEPROM
>>>>> + bool "EEPROM on I2C bus"
>>>>> + help
>>>>> + This switch enables checks for an EEPROM on the I2C bus.
>>>>> Naturally
>>>>> + this will only work if there is an actual EEPROM connected on
>>>>> the
>>>>> + I2C bus and the bus and device are properly configured via the
>>>>> + options below.
>>>>> +
>>>>> +config NET_ETHADDR_EEPROM_I2C_BUS
>>>>> + depends on NET_ETHADDR_EEPROM_I2C
>>>>> + int "I2C bus"
>>>>> + default 0
>>>>> + help
>>>>> + Select the bus on which the EEPROM is present, defaults to bus
>>>>> 0.
>>>>> + Remember to also make the selected bus available via
>>>>> I2Cn_ENABLE.
>>>>> +
>>>>> +config NET_ETHADDR_EEPROM_I2C_ADDR
>>>>> + depends on NET_ETHADDR_EEPROM_I2C
>>>>> + hex "EEPROM address"
>>>>> + default 0x50
>>>>> + help
>>>>> + Select the address of the EEPROM, defaults to address 0x50.
>>>>> +
>>>>> +config NET_ETHADDR_EEPROM_I2C_ADDRLEN
>>>>> + depends on NET_ETHADDR_EEPROM_I2C
>>>>> + int "EEPROM address length"
>>>>> + default 1
>>>>> + help
>>>>> + Number of bytes to be used for the I2C address length.
>>>>> Typically 1,
>>>>> + 2 for large memories, 0 for register type devices with only one
>>>>> + register.
>>>>> +
>>>>> +config NET_ETHADDR_EEPROM_OFFSET
>>>>> + depends on NET_ETHADDR_EEPROM
>>>>> + int "EEPROM offset"
>>>>> + default 8
>>>>> + help
>>>>> + Select the byte offset of the MAC address within the page,
>>>>> + defaults to byte 8.
>>>>
>>>> I would prefer to all these values to be in hex because i2c commands are
>>>> also taking values in hex.
>>>
>>> You are completly right and this is indeed my mistake. I will fix it for
>>> v2.
>>>
>>> Incidently I put them on 0x50 in my own config files for this exact
>>> reason. I probably did not realise I could make it default to hex :)
>>
>> ok.
>>
>>>>> +
>>>>> +config NET_ETHADDR_EEPROM_CRC8
>>>>> + depends on NET_ETHADDR_EEPROM
>>>>> + bool "Check CRC8 of MAC"
>>>>> + default y
>>>>> + help
>>>>> + Optionally, it is possible to run a CRC-8-CCITT check on the MAC
>>>>> + address. To do so, the MAC address is stored with a CRC8 byte
>>>>> append.
>>>>> + This option enables the CRC check of the MAC address against
>>>>> the CRC
>>>>> + byte.
>>>>> +
>>>>
>>>> Would it be possible to have default n here?
>>>> I would guess that more boards don't have this CRC8 sums.
>>>
>>> I agree, but most boards will not use this by default yet. If you enable
>>> this feature for your board, I strongly strongly recommend enabeling
>>> this feature as well. Thus disable it by user request.
>>
>> Hard to do it for boards in the field. As you see we have this feature
>> enabled for zcu102 and also zybo board and there is no crc8 sums factory
>> programmed.
>
> And that's why it is an option. If you turn on this option in your
> (board)config, you have the option as a board maintainer to set the crc8 to
> off, because you have boards in the field already. If I add a new board now
> however, and want to use this feature, it should not be to easy to disable
> it.
>>
>>
>>> Reason why I strongly recommend to enable it: If i have an unprogrammed
>>> eeprom, it comes filled with 0xffffffff. Which is interpreted as a
>>> correct mac address. What if i have random garbage in the eeprom (or a
>>> user change one bit by accident). I still have a valid mac address.
>>> Using the crc8 to validate the mac address makes this a lot more safe.
>>
>> Isn't 0xffffffff invalid address? I think I saw it as invalid.
>
> I know 0x000000 is 'invalid' 0xffffffff might be indeed. but random bits are
> valid mac addresses.
It is perfectly valid, just not as your board's MAC address. It is the
link-wide broadcast address. See is_broadcast_ethaddr()
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