Configuring nvsram (anvo) 1Mb on board with i.mx8mp

[gaurav_bankar]

Hello, 

  I want to configure nvSRAM ANV32AA1W from anvo into my customized board with i.mx8mp processor. 

  I have included it in DTS as follows 

&ecspi2 {

#address-cells = <1>;

#size-cells = <0>;

fsl,spi-num-chipselects = <1>;

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_ecspi2 &pinctrl_ecspi2_cs>;  

cs-gpios = <&gpio5 13 GPIO_ACTIVE_LOW>;

status = "okay";

nvram: nvram@0 {  

compatible = "anvo,anv32aa1w", "atmel,at25";

reg = <0>;

spi-max-frequency = <20000000>;

spi-cpha;

spi-cpol;

pagesize = <128>;

size = <131072>;

address-width = <24>;

};

};

and pinctrl as follows 

pinctrl_ecspi2: ecspi2grp {

fsl,pins = <

MX8MP_IOMUXC_ECSPI2_SCLK__ECSPI2_SCLK 0x82

MX8MP_IOMUXC_ECSPI2_MOSI__ECSPI2_MOSI 0x82

MX8MP_IOMUXC_ECSPI2_MISO__ECSPI2_MISO 0x82

>;

};

pinctrl_ecspi2_cs: ecspi2cs {

fsl,pins = <

MX8MP_IOMUXC_ECSPI2_SS0__GPIO5_IO13 0x40000

>;

};

Is this correctly mentioned in the DTS? I am not able to see this device in the /dev directory. How can I access this memory in the user space? 

[gaurav_bankar]

Hello @Sanket_Parekh, 

  We have changed our dts to be compatible with microchip mchp23k256/mchp23lcv1024. This is the driver for microchip SPI based sram. 

 Here is the DTS 

&ecspi2 {

fsl,spi-num-chipselects = <1>;

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_ecspi2>;  

status = "okay";

nvram:spi-sram@0{  

#address-cells = <1>;

#size-cells = <1>;  

  compatible = "anvo,anv32aa1w","microchip,mchp23lcv1024";

reg = <0>;

spi-max-frequency = <40000000>;             

};

};

here is the iomux pincrtl

pinctrl_ecspi2: ecspi2grp {

fsl,pins = <

MX8MP_IOMUXC_ECSPI2_SCLK__ECSPI2_SCLK 0x1c2

MX8MP_IOMUXC_ECSPI2_MOSI__ECSPI2_MOSI 0x1c2

MX8MP_IOMUXC_ECSPI2_MISO__ECSPI2_MISO 0x82

MX8MP_IOMUXC_ECSPI2_SS0__ECSPI2_SS0 0x1c2

>;

};

With this change I am able to get nvram as a mtd device 

root@taswp500:~# cat /proc/mtd
dev: size erasesize name
mtd0: 00020000 00000000 "spi0.0"
mtd1: 02000000 00010000 "30bb0000.spi"

But the erasesize is zero.

root@taswp500:/sys/bus/nvmem/devices# ls
imx-ocotp0 mtd0 mtd1
root@taswp500:/sys/bus/nvmem/devices# cd mtd0/
root@taswp500:/sys/bus/nvmem/devices/mtd0# ls -l
total 0
-r--r--r-- 1 root root 4096 Jun 12 10:52 consumers
-r-------- 1 root root 0 Jun 12 10:52 nvmem
drwxr-xr-x 2 root root 0 Jun 12 10:52 power
lrwxrwxrwx 1 root root 0 Jun 12 10:08 subsystem -> ../../../../../../../../../../../bus/nvmem
-r--r--r-- 1 root root 4096 Jun 12 10:52 suppliers
-r--r--r-- 1 root root 4096 Jun 12 10:52 type
-rw-r--r-- 1 root root 4096 Jun 12 10:08 uevent

As per your previous comment,  I am not able to read/write at /sys/bus/nvmem/devices/<device_name>/nvmem. 

What should I do next? 

 

[gaurav_bankar]

Hello, 

  Thank you for your reply.

I have made the necessary changes as per above suggestions

 CONFIG_NVMEM = y and CONFIG_EEPROM_AT25=y

I have also changed iomux pincrtl as follows 

pinctrl_ecspi2: ecspi2grp {

fsl,pins = <

MX8MP_IOMUXC_ECSPI2_SCLK__ECSPI2_SCLK 0x1c2

MX8MP_IOMUXC_ECSPI2_MOSI__ECSPI2_MOSI 0x1c2

MX8MP_IOMUXC_ECSPI2_MISO__ECSPI2_MISO 0x82

MX8MP_IOMUXC_ECSPI2_SS0__GPIO5_IO13 0x82

>;

};

But I am not getting any devices in /sys/bus/nvmem/devices/. 

Am I still missing anything? Please suggest any solution. Thank you.

[gaurav_bankar]

Hello @Sanket_Parekh , 

 Thank you for the clarification. I will make sure the option is enabled in the kernel configuration and test it. Here is the bootlog. 

 Also after everything is correct will I get an entry in /dev as /dev/nvram? How will my nvram be mounted in the rootfs?

[Sanket_Parekh]

Hi @gaurav_bankar 

I hope you are doing well.

Please add the below-mentioned option in the kernel for the nvmem interface.

CONFIG_NVMEM = y

Please use the below command to list nvmem devices.

# ls /sys/bus/nvmem/devices/

Also after everything is correct will I get an entry in /dev as /dev/nvram?

[Ans]: /dev/nvram might not be available 

 One can read nvmem data using the below-mentioned command.

# hexdump /sys/bus/nvmem/devices/<device_name>/nvmem

One can read/write nvmem data at /sys/bus/nvmem/devices/<device_name>/nvmem.

Please refer to the below-mentioned kernel documentation.

1. linux-imx/Documentation/driver-api/nvmem.rst

2. linux-imx/Documentation/ABI/stable/sysfs-bus-nvmem

Thanks & Regards,

Sanket Parekh

[Sanket_Parekh]

Hi @gaurav_bankar 

I hope you are doing well.

device tree changes look correct.

Please make sure that the driver with compatible properties "anvo,anv32aa1w", "atmel,at25"; is correctly enabled in the kernel configuration.

Please make sure that below mentioned option is enabled in the kernel configuration.

CONFIG_EEPROM_AT25=y

Please share boot logs for further debugging.

Thanks & Regards

Sanket Parekh