netdev - Re: [PATCH v3 1/2] of_net: Implement of_get_nvmem_mac

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Date:   Thu, 29 Mar 2018 07:31:27 +0200
From:   Mike Looijmans <mike.looijmans@...ic.nl>
To:     Florian Fainelli <f.fainelli@...il.com>, <netdev@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <andrew@...n.ch>, <robh+dt@...nel.org>, <frowand.list@...il.com>
Subject: Re: [PATCH v3 1/2] of_net: Implement of_get_nvmem_mac_address helper

On 28-03-18 00:50, Florian Fainelli wrote:
> On 03/27/2018 02:52 AM, Mike Looijmans wrote:
>> It's common practice to store MAC addresses for network interfaces into
>> nvmem devices. However the code to actually do this in the kernel lacks,
>> so this patch adds of_get_nvmem_mac_address() for drivers to obtain the
>> address from an nvmem cell provider.
>>
>> This is particulary useful on devices where the ethernet interface cannot
>> be configured by the bootloader, for example because it's in an FPGA.
>>
>> Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
>> ---
>>   Documentation/devicetree/bindings/net/ethernet.txt |  2 ++
>>   drivers/of/of_net.c                                | 40 ++++++++++++++++++++++
>>   include/linux/of_net.h                             |  6 ++++
>>   3 files changed, 48 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/net/ethernet.txt b/Documentation/devicetree/bindings/net/ethernet.txt
>> index 2974e63..cfc376b 100644
>> --- a/Documentation/devicetree/bindings/net/ethernet.txt
>> +++ b/Documentation/devicetree/bindings/net/ethernet.txt
>> @@ -10,6 +10,8 @@ Documentation/devicetree/bindings/phy/phy-bindings.txt.
>>     the boot program; should be used in cases where the MAC address assigned to
>>     the device by the boot program is different from the "local-mac-address"
>>     property;
>> +- nvmem-cells: phandle, reference to an nvmem node for the MAC address;
>> +- nvmem-cell-names: string, should be "mac-address" if nvmem is to be used;
>>   - max-speed: number, specifies maximum speed in Mbit/s supported by the device;
>>   - max-frame-size: number, maximum transfer unit (IEEE defined MTU), rather than
>>     the maximum frame size (there's contradiction in the Devicetree
>> diff --git a/drivers/of/of_net.c b/drivers/of/of_net.c
>> index d820f3e..1c5d372 100644
>> --- a/drivers/of/of_net.c
>> +++ b/drivers/of/of_net.c
>> @@ -7,6 +7,7 @@
>>    */
>>   #include <linux/etherdevice.h>
>>   #include <linux/kernel.h>
>> +#include <linux/nvmem-consumer.h>
>>   #include <linux/of_net.h>
>>   #include <linux/phy.h>
>>   #include <linux/export.h>
>> @@ -80,3 +81,42 @@ const void *of_get_mac_address(struct device_node *np)
>>   	return of_get_mac_addr(np, "address");
>>   }
>>   EXPORT_SYMBOL(of_get_mac_address);
>> +
>> +/**
>> + * Obtain the MAC address from an nvmem provider named 'mac-address' through
>> + * device tree.
>> + * On success, copies the new address into memory pointed to by addr and
>> + * returns 0. Returns a negative error code otherwise.
>> + * @np:		Device tree node containing the nvmem-cells phandle
>> + * @addr:	Pointer to receive the MAC address using ether_addr_copy()
>> + */
>> +int of_get_nvmem_mac_address(struct device_node *np, void *addr)
>> +{
>> +	struct nvmem_cell *cell;
>> +	const void *mac;
>> +	size_t len;
>> +	int ret;
>> +
>> +	cell = of_nvmem_cell_get(np, "mac-address");
>> +	if (IS_ERR(cell))
>> +		return PTR_ERR(cell);
>> +
>> +	mac = nvmem_cell_read(cell, &len);
>> +
>> +	nvmem_cell_put(cell);
>> +
>> +	if (IS_ERR(mac))
>> +		return PTR_ERR(mac);
>> +
>> +	if (len < 6 || !is_valid_ether_addr(mac)) {
>> +		ret = -EINVAL;
> 
> Just one nit here, can you use ETH_ALEN instead of 6? With that fixed:
> 
> Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
> 

Ok, implemented and tested it, and v4 is on the way with that change.


Kind regards,

Mike Looijmans
System Expert

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