[net-next,6/6] net: mvpp2: Consider NVMEM cells as possible MAC address source

The ONIE standard describes the organization of tlv (type-length-value)
arrays commonly stored within NVMEM devices on common networking
hardware.

Several drivers already make use of NVMEM cells for purposes like
retrieving a default MAC address provided by the manufacturer.

What made ONIE tables unusable so far was the fact that the information
where "dynamically" located within the table depending on the
manufacturer wishes, while Linux NVMEM support only allowed statically
defined NVMEM cells. Fortunately, this limitation was eventually tackled
with the introduction of discoverable cells through the use of NVMEM
layouts, making it possible to extract and consistently use the content
of tables like ONIE's tlv arrays.

Parsing this table at runtime in order to get various information is now
possible. So, because many Marvell networking switches already follow
this standard, let's consider using NVMEM cells as a new valid source of
information when looking for a base MAC address, which is one of the
primary uses of these new fields. Indeed, manufacturers following the
ONIE standard are encouraged to provide a default MAC address there, so
let's eventually use it if no other MAC address has been found using the
existing methods.

Link: https://opencomputeproject.github.io/onie/design-spec/hw_requirements.html
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 6 ++++++
 1 file changed, 6 insertions(+)

Hi Marcin,

mw@semihalf.com wrote on Sat, 19 Nov 2022 09:18:34 +0100:

> Hi Miquel,
> 
> 
> czw., 17 lis 2022 o 22:56 Miquel Raynal <miquel.raynal@bootlin.com> napisał(a):
> >
> > The ONIE standard describes the organization of tlv (type-length-value)
> > arrays commonly stored within NVMEM devices on common networking
> > hardware.
> >
> > Several drivers already make use of NVMEM cells for purposes like
> > retrieving a default MAC address provided by the manufacturer.
> >
> > What made ONIE tables unusable so far was the fact that the information
> > where "dynamically" located within the table depending on the
> > manufacturer wishes, while Linux NVMEM support only allowed statically
> > defined NVMEM cells. Fortunately, this limitation was eventually tackled
> > with the introduction of discoverable cells through the use of NVMEM
> > layouts, making it possible to extract and consistently use the content
> > of tables like ONIE's tlv arrays.
> >
> > Parsing this table at runtime in order to get various information is now
> > possible. So, because many Marvell networking switches already follow
> > this standard, let's consider using NVMEM cells as a new valid source of
> > information when looking for a base MAC address, which is one of the
> > primary uses of these new fields. Indeed, manufacturers following the
> > ONIE standard are encouraged to provide a default MAC address there, so
> > let's eventually use it if no other MAC address has been found using the
> > existing methods.
> >
> > Link: https://opencomputeproject.github.io/onie/design-spec/hw_requirements.html  
> 
> Thanks for the patch. Did you manage to test in on a real HW? I am curious about

Yes, I have a Replica switch on which the commercial ports use the
replica PCI IP while the config "OOB" port is running with mvpp2:
[   16.737759] mvpp2 f2000000.ethernet eth52: Using nvmem cell mac address 18:be:92:13:9a:00

> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> >  drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > index eb0fb8128096..7c8c323f4411 100644
> > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > @@ -6104,6 +6104,12 @@ static void mvpp2_port_copy_mac_addr(struct net_device *dev, struct mvpp2 *priv,
> >                 }
> >         }
> >
> > +       if (!of_get_mac_address(to_of_node(fwnode), hw_mac_addr)) {  
> 
> Unfortunately, nvmem cells seem to be not supported with ACPI yet, so
> we cannot extend fwnode_get_mac_address - I think it should be,
> however, an end solution.

Agreed.

> As of now, I'd prefer to use of_get_mac_addr_nvmem directly, to avoid
> parsing the DT again (after fwnode_get_mac_address) and relying
> implicitly on falling back to nvmem stuff (currently, without any
> comment it is not obvious).

I did not do that in the first place because of_get_mac_addr_nvmem()
was not exported, but I agree it would be the cleanest (and quickest)
approach, so I'll attempt to export the function first, and then use it
directly from the driver.

> Best regards,
> Marcin
> 
> > +               *mac_from = "nvmem cell";
> > +               eth_hw_addr_set(dev, hw_mac_addr);
> > +               return;
> > +       }
> > +
> >         *mac_from = "random";
> >         eth_hw_addr_random(dev);
> >  }
> > --
> > 2.34.1
> >  

Thanks a lot,
Miquèl

pon., 21 lis 2022 o 10:29 Miquel Raynal <miquel.raynal@bootlin.com> napisał(a):
>
> Hi Marcin,
>
> mw@semihalf.com wrote on Sat, 19 Nov 2022 09:18:34 +0100:
>
> > Hi Miquel,
> >
> >
> > czw., 17 lis 2022 o 22:56 Miquel Raynal <miquel.raynal@bootlin.com> napisał(a):
> > >
> > > The ONIE standard describes the organization of tlv (type-length-value)
> > > arrays commonly stored within NVMEM devices on common networking
> > > hardware.
> > >
> > > Several drivers already make use of NVMEM cells for purposes like
> > > retrieving a default MAC address provided by the manufacturer.
> > >
> > > What made ONIE tables unusable so far was the fact that the information
> > > where "dynamically" located within the table depending on the
> > > manufacturer wishes, while Linux NVMEM support only allowed statically
> > > defined NVMEM cells. Fortunately, this limitation was eventually tackled
> > > with the introduction of discoverable cells through the use of NVMEM
> > > layouts, making it possible to extract and consistently use the content
> > > of tables like ONIE's tlv arrays.
> > >
> > > Parsing this table at runtime in order to get various information is now
> > > possible. So, because many Marvell networking switches already follow
> > > this standard, let's consider using NVMEM cells as a new valid source of
> > > information when looking for a base MAC address, which is one of the
> > > primary uses of these new fields. Indeed, manufacturers following the
> > > ONIE standard are encouraged to provide a default MAC address there, so
> > > let's eventually use it if no other MAC address has been found using the
> > > existing methods.
> > >
> > > Link: https://opencomputeproject.github.io/onie/design-spec/hw_requirements.html
> >
> > Thanks for the patch. Did you manage to test in on a real HW? I am curious about
>
> Yes, I have a Replica switch on which the commercial ports use the
> replica PCI IP while the config "OOB" port is running with mvpp2:
> [   16.737759] mvpp2 f2000000.ethernet eth52: Using nvmem cell mac address 18:be:92:13:9a:00
>

Nice. Do you have a DT snippet that can possibly be shared? I'd like
to recreate this locally and eventually leverage EDK2 firmware to
expose that.

> > > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > > ---
> > >  drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > index eb0fb8128096..7c8c323f4411 100644
> > > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > @@ -6104,6 +6104,12 @@ static void mvpp2_port_copy_mac_addr(struct net_device *dev, struct mvpp2 *priv,
> > >                 }
> > >         }
> > >
> > > +       if (!of_get_mac_address(to_of_node(fwnode), hw_mac_addr)) {
> >
> > Unfortunately, nvmem cells seem to be not supported with ACPI yet, so
> > we cannot extend fwnode_get_mac_address - I think it should be,
> > however, an end solution.
>
> Agreed.
>
> > As of now, I'd prefer to use of_get_mac_addr_nvmem directly, to avoid
> > parsing the DT again (after fwnode_get_mac_address) and relying
> > implicitly on falling back to nvmem stuff (currently, without any
> > comment it is not obvious).
>
> I did not do that in the first place because of_get_mac_addr_nvmem()
> was not exported, but I agree it would be the cleanest (and quickest)
> approach, so I'll attempt to export the function first, and then use it
> directly from the driver.
>

That would be great, thank you. Please add one-comment in the
mvpp2_main.c, that this is valid for now only in DT world.

Best regards,
Marcin

Hi Marcin,

mw@semihalf.com wrote on Mon, 21 Nov 2022 15:46:44 +0100:

> pon., 21 lis 2022 o 10:29 Miquel Raynal <miquel.raynal@bootlin.com> napisał(a):
> >
> > Hi Marcin,
> >
> > mw@semihalf.com wrote on Sat, 19 Nov 2022 09:18:34 +0100:
> >  
> > > Hi Miquel,
> > >
> > >
> > > czw., 17 lis 2022 o 22:56 Miquel Raynal <miquel.raynal@bootlin.com> napisał(a):  
> > > >
> > > > The ONIE standard describes the organization of tlv (type-length-value)
> > > > arrays commonly stored within NVMEM devices on common networking
> > > > hardware.
> > > >
> > > > Several drivers already make use of NVMEM cells for purposes like
> > > > retrieving a default MAC address provided by the manufacturer.
> > > >
> > > > What made ONIE tables unusable so far was the fact that the information
> > > > where "dynamically" located within the table depending on the
> > > > manufacturer wishes, while Linux NVMEM support only allowed statically
> > > > defined NVMEM cells. Fortunately, this limitation was eventually tackled
> > > > with the introduction of discoverable cells through the use of NVMEM
> > > > layouts, making it possible to extract and consistently use the content
> > > > of tables like ONIE's tlv arrays.
> > > >
> > > > Parsing this table at runtime in order to get various information is now
> > > > possible. So, because many Marvell networking switches already follow
> > > > this standard, let's consider using NVMEM cells as a new valid source of
> > > > information when looking for a base MAC address, which is one of the
> > > > primary uses of these new fields. Indeed, manufacturers following the
> > > > ONIE standard are encouraged to provide a default MAC address there, so
> > > > let's eventually use it if no other MAC address has been found using the
> > > > existing methods.
> > > >
> > > > Link: https://opencomputeproject.github.io/onie/design-spec/hw_requirements.html  
> > >
> > > Thanks for the patch. Did you manage to test in on a real HW? I am curious about  
> >
> > Yes, I have a Replica switch on which the commercial ports use the
> > replica PCI IP while the config "OOB" port is running with mvpp2:
> > [   16.737759] mvpp2 f2000000.ethernet eth52: Using nvmem cell mac address 18:be:92:13:9a:00
> >  
> 
> Nice. Do you have a DT snippet that can possibly be shared? I'd like
> to recreate this locally and eventually leverage EDK2 firmware to
> expose that.

Yes of course, the DT is public on Sartura's Github, but here is the
exact file I used showing the diff cleaning the Armada 7040 TN48M DT
eeprom description and its use as an nvmem-cell provider):
https://github.com/miquelraynal/linux/commit/230ee68728799454e2f07f61792e11724e731d6d

> 
> > > > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > > > ---
> > > >  drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 6 ++++++
> > > >  1 file changed, 6 insertions(+)
> > > >
> > > > diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > > index eb0fb8128096..7c8c323f4411 100644
> > > > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > > @@ -6104,6 +6104,12 @@ static void mvpp2_port_copy_mac_addr(struct net_device *dev, struct mvpp2 *priv,
> > > >                 }
> > > >         }
> > > >
> > > > +       if (!of_get_mac_address(to_of_node(fwnode), hw_mac_addr)) {  
> > >
> > > Unfortunately, nvmem cells seem to be not supported with ACPI yet, so
> > > we cannot extend fwnode_get_mac_address - I think it should be,
> > > however, an end solution.  
> >
> > Agreed.
> >  
> > > As of now, I'd prefer to use of_get_mac_addr_nvmem directly, to avoid
> > > parsing the DT again (after fwnode_get_mac_address) and relying
> > > implicitly on falling back to nvmem stuff (currently, without any
> > > comment it is not obvious).  
> >
> > I did not do that in the first place because of_get_mac_addr_nvmem()
> > was not exported, but I agree it would be the cleanest (and quickest)
> > approach, so I'll attempt to export the function first, and then use it
> > directly from the driver.
> >  
> 
> That would be great, thank you. Please add one-comment in the
> mvpp2_main.c, that this is valid for now only in DT world.

Ack.

Thanks,
Miquèl