We are migrating from Buildroot 2018.02.9 (linux-4.14.85) to Buildroot 2020.02.2 (linux-5.4.40), and have found that we can no longer read the MAC address on an I.MX7s SoC. The following indicates why:
Unfortunately OTP driver is not supported anymore, it was moved to NVMEM framework. imx-ocotp.c\nvmem\drivers - linux-imx - i.MX Linux kernel
We are trying to read the MAC address using a standard Linux DTS & device driver approach, ie. without writing extra code. And the aim is for the MAC to be read by the Ethernet driver.
Our Buildroot 20.20 ‘DSM1_kernel_defconfig’ includes:
CONFIG_NVMEM_IMX_OCOTP=y
CONFIG_NVMEM_IMX_IIM=y
The DTS entries for ocotp are assembeled from 2 files:
- linux-5.4.40/arch/arm/boot/dts/imx7s.dtsi :
ocotp: ocotp-ctrl@30350000 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "fsl,imx7d-ocotp", "syscon";
reg = <0x30350000 0x10000>;
clocks = <&clks IMX7D_OCOTP_CLK>;
tempmon_calib: calib@3c {
reg = <0x3c 0x4>;
};
tempmon_temp_grade: temp-grade@10 {
reg = <0x10 0x4>;
};
cpu_speed_grade: speed-grade@10 {
reg = <0x10 0x4>;
};
};
- our local file ‘device-tree/DSM1.dts’ with 2 parts relating to this issue:
a) nvmem-cells and nvmem-cell-names are added to &fec1 as suggested by @alexandre-belloni:
&fec1 {
nvmem-cells = <&MAC0>;
// nvmem-consumer.yaml:
nvmem-cell-names = "mac-address";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_enet1>;
phy-mode = "rgmii";
status = "okay";
fixed-link {
speed = <1000>;
full-duplex;
};
};
b) The following '&ocotp' entry:
&ocotp {
// Subnodes:
MAC0:mac_add0@640{
reg=<0x640 0x4>;
};
MAC1:mac_add1@650{
reg=<0x650 0x4>;
};
MAC2:mac_add2@660{
reg=<0x660 0x4>;
};
};
Links for the above comments:
- https://www.kernel.org/doc/Documentation/devicetree/bindings/net/ethernet-controller.yaml
- http://devicetree.org/schemas/nvmem/nvmem-consumer.yaml (or now https://mjmwired.net/kernel/Documentation/devicetree/bindings/nvmem/nvmem-consumer.yaml).
From the console:
[ 0.547384] fuse: init (API version 7.31)
[ 1.706205] fec 30be0000.ethernet: Invalid MAC address: 00:00:00:00:00:00
[ 1.713049] fec 30be0000.ethernet: Using random MAC address: 3e:ba:4a:d6:f9:60
[ 1.756676] libphy: fec_enet_mii_bus: probed
[ 1.763270] fec 30be0000.ethernet eth0: registered PHC device 0
[ 2.534219] imx_ocotp 30350000.efuse: can't request region for resource [mem 0x30350000-0x3035ffff]
[ 2.543780] imx_ocotp: probe of 30350000.efuse failed with error -16
[ 1.706205] fec 30be0000.ethernet: Invalid MAC address: 00:00:00:00:00:00
[ 1.713049] fec 30be0000.ethernet: Using random MAC address: 3e:ba:4a:d6:f9:60
KSZ8794 VLAN configuration complete
OK
Reading MAC address fuses...
MAC Address fuses not found
Starting network: [ 6.976948] Generic PHY fixed-0:00: attached PHY driver [Generic PHY] (mii_bus:phy_addr=fixed-0:00, irq=POLL)
[ 7.007287] fec 30be0000.ethernet eth0: Link is Up - 1Gbps/Full - flow control off
The MAC on this board is currently unset. We would like to prove that the unset zero value can be successfully read, before moving on to using the MAC in the Ethernet driver. Eventually we will be setting the MAC during production.
Digging around in the Device Tree fails to find anything which we believe to be the unset zero MAC:
ls -l /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@30350000
total 0
-r--r--r-- 1 root root 4 Oct 5 16:39 #address-cells
-r--r--r-- 1 root root 4 Oct 5 16:39 #size-cells
drwxr-xr-x 2 root root 0 Oct 5 16:39 calib@3c
-r--r--r-- 1 root root 8 Oct 5 16:39 clocks
-r--r--r-- 1 root root 23 Oct 5 16:39 compatible
drwxr-xr-x 2 root root 0 Oct 5 16:39 mac_add0@640
drwxr-xr-x 2 root root 0 Oct 5 16:39 mac_add1@650
drwxr-xr-x 2 root root 0 Oct 5 16:39 mac_add2@660
-r--r--r-- 1 root root 11 Oct 5 16:39 name
-r--r--r-- 1 root root 18 Oct 5 16:39 nvmem-cell-names
-r--r--r-- 1 root root 4 Oct 5 16:39 nvmem-cells
-r--r--r-- 1 root root 12 Oct 5 16:39 nvmem-cells-names
-r--r--r-- 1 root root 8 Oct 5 16:39 reg
drwxr-xr-x 2 root root 0 Oct 5 16:39 speed-grade@10
drwxr-xr-x 2 root root 0 Oct 5 16:39 temp-grade@10
Subnodes:
MAC0: ls -la /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@30350000 /mac_add0@640/
total 0
drwxr-xr-x 2 root root 0 Oct 6 08:01 .
drwxr-xr-x 8 root root 0 Oct 6 08:00 ..
-r--r--r-- 1 root root 9 Oct 6 08:01 name
-r--r--r-- 1 root root 4 Oct 6 08:01 phandle
-r--r--r-- 1 root root 8 Oct 6 08:01 reg
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/mac_add0@640/name
0000000 616d 5f63 6461 3064 0000
0000009
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/mac_add0@640/phandle
0000000 0000 2000
0000004
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/mac_add0@640/reg
0000000 0000 4006 0000 0400
0000008
MAC1: ls -la /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@30350000 /mac_add1@650/
total 0
drwxr-xr-x 2 root root 0 Oct 6 08:01 .
drwxr-xr-x 8 root root 0 Oct 6 08:00 ..
-r--r--r-- 1 root root 9 Oct 6 08:01 name
-r--r--r-- 1 root root 8 Oct 6 08:01 reg
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/mac_add1@650/name
0000000 616d 5f63 6461 3164 0000
0000009
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/mac_add1@650/reg
0000000 0000 5006 0000 0400
0000008
MAC2:
ls -la /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@30350000 /mac_add2@660/
total 0
drwxr-xr-x 2 root root 0 Oct 6 08:01 .
drwxr-xr-x 8 root root 0 Oct 6 08:00 ..
-r--r--r-- 1 root root 9 Oct 6 08:01 name
-r--r--r-- 1 root root 8 Oct 6 08:01 reg
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/mac_add2@660/name
0000000 616d 5f63 6461 3264 0000
0000009
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/mac_add2@660/reg
0000000 0000 6006 0000 0400
0000008
Properties:
- pre-move to fec1:
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/nvmem-cells
0000000 0000 2000
0000004
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/nvmem-cells-names
0000000 616d 2d63 6461 7264 7365 0073
000000c
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30000000/ocotp-ctrl@3035000 0/nvmem-cell-names
0000000 6f6c 6163 2d6c 616d 2d63 6461 7264 7365
0000010 0073
0000012
- post-move to fec1:
Edit: following the nvmem-cells & nvmem-cell-names edits as suggested by @alexandre-belloni:
find /sys -name "nvmem" -print
/sys/devices/platform/soc/30800000.aips-bus/30a20000.i2c/i2c-0/0-0068/ds1307_nvram0/nvmem
/sys/devices/platform/soc/30000000.aips-bus/30350000.ocotp-ctrl/imx-ocotp0/nvmem
/sys/firmware/devicetree/base/soc/aips-bus@30800000/ethernet@30be0000/nvmem-cells
/sys/firmware/devicetree/base/soc/aips-bus@30800000/ethernet@30be0000/nvmem-cell-names
/sys/firmware/devicetree/base/cpus/cpu@0/nvmem-cells
/sys/firmware/devicetree/base/cpus/cpu@0/nvmem-cell-names
/sys/firmware/devicetree/base/tempmon/nvmem-cells
/sys/firmware/devicetree/base/tempmon/nvmem-cell-names
/sys/bus/nvmem
hexdump /sys/devices/platform/soc/30800000.aips-bus/30a20000.i2c/i2c-0/0-0068/ds1307_nvram0/nvmem
0000000 9000 b1ae 02e1 4e10 1078 5a12 6444 c5a4
0000010 9a02 e488 c851 69a8 9902 22d3 1e2c 78a8
0000020 21ed ce14 c649 4422 22a9 0360 2b55 c93a
0000030 088a 4234 0ca4 8c88
0000038
hexdump /sys/devices/platform/soc/30000000.aips-bus/30350000.ocotp-ctrl/imx-ocotp0/nvmem
hexdump: /sys/devices/platform/soc/30000000.aips-bus/30350000.ocotp-ctrl/imx-ocotp0/nvmem: Invalid argument
0000000 0103 a003 886a 8ebf 0297 0000
000000c
ls -l /sys/firmware/devicetree/base/soc/aips-bus@30800000/ethernet@30be0000/nvmem-cells
-r--r--r-- 1 root root 4 Oct 6 14:18 /sys/firmware/devicetree/base/soc/aips-bus@30800000/ethernet@30be0000/nvmem-cells
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30800000/ethernet@30be0000/nvmem-cells
0000000 0000 4600
0000004
hexdump /sys/firmware/devicetree/base/soc/aips-bus@30800000/ethernet@30be0000/nvmem-cell-names
0000000 616d 2d63 6461 7264 7365 0073
000000c
hexdump /sys/firmware/devicetree/base/cpus/cpu@0/nvmem-cells
0000000 0000 0400
0000004
hexdump /sys/firmware/devicetree/base/cpus/cpu@0/nvmem-cell-names
0000000 7073 6565 5f64 7267 6461 0065
000000c
hexdump /sys/firmware/devicetree/base/tempmon/nvmem-cells
0000000 0000 0c00 0000 0d00
0000008
hexdump /sys/firmware/devicetree/base/tempmon/nvmem-cell-names
0000000 6163 696c 0062 6574 706d 675f 6172 6564
0000010 0000
0000011
So, were’re obviously doing something wrong, any ideas? All suggestions gratefully received.
