[PATCH v2] net: Add eth_platform_get_mac_address() helper.

[PATCH v2] net: Add eth_platform_get_mac_address() helper.

[David Miller]

A repeating pattern in drivers has become to use OF node information
and, if not found, platform specific host information to extract the
ethernet address for a given device.

Currently this is done with a call to of_get_mac_address() and then
some ifdef'd stuff for SPARC.

Consolidate this into a portable routine, and provide the
arch_get_platform_mac_address() weak function hook for all
architectures to implement if they want.

Signed-off-by: David S. Miller <davem@davemloft.net>
---

As promised back in November, I'm commiting this into net-next
now.  I'd work on the conversions of existing drivers, but I'd
rather someone with access to the hardware to so.

 arch/sparc/kernel/idprom.c  |  7 +++++++
 include/linux/etherdevice.h |  3 +++
 net/ethernet/eth.c          | 31 +++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+)

diff --git a/arch/sparc/kernel/idprom.c b/arch/sparc/kernel/idprom.c
index 6bd7501..f95dd11 100644
--- a/arch/sparc/kernel/idprom.c
+++ b/arch/sparc/kernel/idprom.c
@@ -9,6 +9,7 @@
 #include <linux/types.h>
 #include <linux/init.h>
 #include <linux/export.h>
+#include <linux/etherdevice.h>
 
 #include <asm/oplib.h>
 #include <asm/idprom.h>
@@ -60,6 +61,12 @@ static void __init display_system_type(unsigned char machtype)
 {
 }
 #endif
+
+unsigned char *arch_get_platform_mac_address(void)
+{
+	return idprom->id_ethaddr;
+}
+
 /* Calculate the IDPROM checksum (xor of the data bytes). */
 static unsigned char __init calc_idprom_cksum(struct idprom *idprom)
 {
diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index eb049c6..37ff4a6 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -29,6 +29,9 @@
 #include <asm/bitsperlong.h>
 
 #ifdef __KERNEL__
+struct device;
+int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr);
+unsigned char *arch_get_platform_get_mac_address(void);
 u32 eth_get_headlen(void *data, unsigned int max_len);
 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
 extern const struct header_ops eth_header_ops;
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 9e63f25..1038717 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -52,6 +52,8 @@
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/if_ether.h>
+#include <linux/of_net.h>
+#include <linux/pci.h>
 #include <net/dst.h>
 #include <net/arp.h>
 #include <net/sock.h>
@@ -485,3 +487,32 @@ static int __init eth_offload_init(void)
 }
 
 fs_initcall(eth_offload_init);
+
+unsigned char * __weak arch_get_platform_mac_address(void)
+{
+	return NULL;
+}
+
+int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
+{
+	const unsigned char *addr;
+	struct device_node *dp;
+
+	if (dev_is_pci(dev))
+		dp = pci_device_to_OF_node(to_pci_dev(dev));
+	else
+		dp = dev->of_node;
+
+	addr = NULL;
+	if (dp)
+		addr = of_get_mac_address(dp);
+	if (!addr)
+		addr = arch_get_platform_mac_address();
+
+	if (!addr)
+		return -ENODEV;
+
+	ether_addr_copy(mac_addr, addr);
+	return 0;
+}
+EXPORT_SYMBOL(eth_platform_get_mac_address);
-- 
2.4.1

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[Sowmini Varadhan]

On (01/06/16 16:33), David Miller wrote:
> 
> Signed-off-by: David S. Miller <davem@davemloft.net>

Acked-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>

> 
> As promised back in November, I'm commiting this into net-next
> now.  I'd work on the conversions of existing drivers, but I'd
> rather someone with access to the hardware to so.

I'll look into this.

--Sowmini

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[Joe Perches]

On Wed, 2016-01-06 at 16:33 -0500, David Miller wrote:
> A repeating pattern in drivers has become to use OF node information
> and, if not found, platform specific host information to extract the
> ethernet address for a given device.
[]
> diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
[]
> @@ -485,3 +487,32 @@ static int __init eth_offload_init(void)
>  }
>  
>  fs_initcall(eth_offload_init);
> +
> +unsigned char * __weak arch_get_platform_mac_address(void)
> +{
> +       return NULL;

WARN_ON_ONCE ?

> +}
> +
> +int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
> +{
> +       const unsigned char *addr;
> +       struct device_node *dp;
> +
> +       if (dev_is_pci(dev))
> +               dp = pci_device_to_OF_node(to_pci_dev(dev));
> +       else
> +               dp = dev->of_node;
> +
> +       addr = NULL;
> +       if (dp)
> +               addr = of_get_mac_address(dp);
> +       if (!addr)
> +               addr = arch_get_platform_mac_address();
> +
> +       if (!addr)
> +               return -ENODEV;
> +
> +       ether_addr_copy(mac_addr, addr);

Couldn't some oddball arch have an unaligned addr?

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[Bjørn Mork]

Joe Perches <joe@perches.com> writes:
> On Wed, 2016-01-06 at 16:33 -0500, David Miller wrote:
>> A repeating pattern in drivers has become to use OF node information
>> and, if not found, platform specific host information to extract the
>> ethernet address for a given device.
> []
>> diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
> []
>> @@ -485,3 +487,32 @@ static int __init eth_offload_init(void)
>>  }
>>  
>>  fs_initcall(eth_offload_init);
>> +
>> +unsigned char * __weak arch_get_platform_mac_address(void)
>> +{
>> +       return NULL;
>
> WARN_ON_ONCE ?

That would prevent a driver from using this with additional fallback
methods.  For what reason?

I don't have a specific usecase, but I can imagine drivers falling back
to e.g a random address without wanting to be noisy about it.


Bjørn

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[Joe Perches]

On Thu, 2016-01-07 at 00:26 +0100, Bjørn Mork wrote:
> Joe Perches <joe@perches.com> writes:
> > On Wed, 2016-01-06 at 16:33 -0500, David Miller wrote:
> > > A repeating pattern in drivers has become to use OF node information
> > > and, if not found, platform specific host information to extract the
> > > ethernet address for a given device.
> > []
> > > diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
> > []
> > > @@ -485,3 +487,32 @@ static int __init eth_offload_init(void)
> > >  }
> > >  
> > >  fs_initcall(eth_offload_init);
> > > +
> > > +unsigned char * __weak arch_get_platform_mac_address(void)
> > > +{
> > > +       return NULL;
> > 
> > WARN_ON_ONCE ?
> 
> That would prevent a driver from using this with additional fallback
> methods.  For what reason?

It's declared __weak and should be overridden by
an arch specific function.

A NULL address would cause a fault when using
a function like copy_ether_addr.


> I don't have a specific usecase, but I can imagine drivers falling back
> to e.g a random address without wanting to be noisy about it.

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[Bjørn Mork]

Joe Perches <joe@perches.com> writes:
> On Thu, 2016-01-07 at 00:26 +0100, Bjørn Mork wrote:
>> Joe Perches <joe@perches.com> writes:
>> > On Wed, 2016-01-06 at 16:33 -0500, David Miller wrote:
>> > > A repeating pattern in drivers has become to use OF node information
>> > > and, if not found, platform specific host information to extract the
>> > > ethernet address for a given device.
>> > []
>> > > diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
>> > []
>> > > @@ -485,3 +487,32 @@ static int __init eth_offload_init(void)
>> > >  }
>> > >  
>> > >  fs_initcall(eth_offload_init);
>> > > +
>> > > +unsigned char * __weak arch_get_platform_mac_address(void)
>> > > +{
>> > > +       return NULL;
>> > 
>> > WARN_ON_ONCE ?
>> 
>> That would prevent a driver from using this with additional fallback
>> methods.  For what reason?
>
> It's declared __weak and should be overridden by
> an arch specific function.

"should"?  Why?  Do you have a suggested implementation for - say - x86?

> A NULL address would cause a fault when using
> a function like copy_ether_addr.

You should not do that then :)


Bjørn

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[David Miller]

From: Joe Perches <joe@perches.com>
Date: Wed, 06 Jan 2016 15:32:24 -0800

> On Thu, 2016-01-07 at 00:26 +0100, Bjørn Mork wrote:
>> Joe Perches <joe@perches.com> writes:
>> > On Wed, 2016-01-06 at 16:33 -0500, David Miller wrote:
>> > > A repeating pattern in drivers has become to use OF node information
>> > > and, if not found, platform specific host information to extract the
>> > > ethernet address for a given device.
>> > []
>> > > diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
>> > []
>> > > @@ -485,3 +487,32 @@ static int __init eth_offload_init(void)
>> > >  }
>> > >  
>> > >  fs_initcall(eth_offload_init);
>> > > +
>> > > +unsigned char * __weak arch_get_platform_mac_address(void)
>> > > +{
>> > > +       return NULL;
>> > 
>> > WARN_ON_ONCE ?
>> 
>> That would prevent a driver from using this with additional fallback
>> methods.  For what reason?
> 
> It's declared __weak and should be overridden by
> an arch specific function.
> 
> A NULL address would cause a fault when using
> a function like copy_ether_addr.

The caller checks for NULL, and this is the default implementation
doing precisely what it is meant to do.

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[Joe Perches]

On Wed, 2016-01-06 at 19:01 -0500, David Miller wrote:
> The caller checks for NULL, and this is the default implementation
> doing precisely what it is meant to do.

Yeah, I noticed that later. Nevermind...

cheers, Joe

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[Sowmini Varadhan]

On (01/06/16 16:33), David Miller wrote:
> 
> A repeating pattern in drivers has become to use OF node information
> and, if not found, platform specific host information to extract the
> ethernet address for a given device.
    :
> Consolidate this into a portable routine, and provide the
> arch_get_platform_mac_address() weak function hook for all
> architectures to implement if they want.
    :
> As promised back in November, I'm commiting this into net-next
> now.  I'd work on the conversions of existing drivers, but I'd
> rather someone with access to the hardware to so.

I finally have all the ducks lined up for ixgbe/i40e around this. 
Should I go ahead and send this off (I think it first gets staged 
through Jeff's repo?) or is it better to wait for net-next to be 
open again?

--Sowmini

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[Kirsher, Jeffrey T]

> On Jan 12, 2016, at 16:49, Sowmini Varadhan <sowmini.varadhan@oracle.com> wrote:
> 
>> On (01/06/16 16:33), David Miller wrote:
>> 
>> A repeating pattern in drivers has become to use OF node information
>> and, if not found, platform specific host information to extract the
>> ethernet address for a given device.
>    :
>> Consolidate this into a portable routine, and provide the
>> arch_get_platform_mac_address() weak function hook for all
>> architectures to implement if they want.
>    :
>> As promised back in November, I'm commiting this into net-next
>> now.  I'd work on the conversions of existing drivers, but I'd
>> rather someone with access to the hardware to so.
> 
> I finally have all the ducks lined up for ixgbe/i40e around this. 
> Should I go ahead and send this off (I think it first gets staged 
> through Jeff's repo?) or is it better to wait for net-next to be 
> open again?

please go ahead and send it to intel-wired-lan@lists.osuosl.org so we can review and test the driver parts so when net-next opens it should be ready to push upstream.

Re: [PATCH v2] net: Add eth_platform_get_mac_address() helper.

[David Miller]

From: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Date: Tue, 12 Jan 2016 19:49:16 -0500

> I finally have all the ducks lined up for ixgbe/i40e around this. 
> Should I go ahead and send this off (I think it first gets staged 
> through Jeff's repo?) or is it better to wait for net-next to be 
> open again?

If you want to send it to Jeff and the Intel folks for them to
queue it up there, that's fine.