Linux/AM3352: m25p80 flash chip not seen in kernel but found in u-boot

Richard McAleer

Part Number: AM3352

Tool/software: Linux

Hi

I am working with a design that's based on the BeagleBoneBlack and using the latest SDK & tools for the am3352?

Can anyone advise me how I should enable support for an m25p80 SPI flash chip in my kernel?

I have had a look through previously posted questions and followed what examples I have been able to find, but I am not having much luck.

I can access the chip from u-boot and have used it to read my kernel and DTB.

I have defined the flash in the DTS as

&spi0 {
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&spi0_pins>;

    spi-flash@0 {
        compatible = "micron,n25q256a", "m25p80";
        spi-max-frequency = <48000000>;
        reg = <0>;
                  #address-cells = <1>;
                   #size-cells = <1>;
                   partition@0 {
                      label = "SPL";
                      reg = <0x00000000 0x00020000>;
                   };
                   partition@20000 {
                      label = "u-boot";
                      reg = <0x00020000 0x00066000>;
                   };
                   partition@86000 {
                      label = "dtb";
                      reg = <0x00086000 0x00010000>;
                   };
                   partition@96000 {
                      label = "kernel";
                      reg = <0x00960000 0x0050a000>;
                   };
                   partition@5a0000 {
                      label = "-";
                      reg = <0x005a0000 0x01a60000>;
                   };
     };
};

Within my .config I can see that I have

#
# Self-contained MTD device drivers
#
# CONFIG_MTD_PMC551 is not set
# CONFIG_MTD_DATAFLASH is not set
CONFIG_MTD_M25P80=y
# CONFIG_MTD_SST25L is not set
# CONFIG_MTD_SLRAM is not set
# CONFIG_MTD_PHRAM is not set
# CONFIG_MTD_MTDRAM is not set
CONFIG_MTD_BLOCK2MTD=y

#
# LPDDR & LPDDR2 PCM memory drivers
#
# CONFIG_MTD_LPDDR is not set
# CONFIG_MTD_LPDDR2_NVM is not set
CONFIG_MTD_SPI_NOR=y
CONFIG_MTD_SPI_NOR_USE_4K_SECTORS=y
CONFIG_MTD_UBI=y
CONFIG_MTD_UBI_WL_THRESHOLD=4096
CONFIG_MTD_UBI_BEB_LIMIT=20
# CONFIG_MTD_UBI_FASTMAP is not set
# CONFIG_MTD_UBI_GLUEBI is not set
# CONFIG_MTD_UBI_BLOCK is not set
CONFIG_DTC=y

Once the kernel is running however there are no /dev/mtd* devices.
There is nothing in /proc/mtd nor sys/class/mtd

Thanks for any suggestions for how I might big deeper

Kind regards,
Richard

over 9 years ago

0 Yordan Kovachev over 9 years ago

TI__Guru**** 161600 points

Hi Richard,

Can you try adding:
spi-flash@0 {
compatible = "micron,n25q256a", "m25p80";
spi-max-frequency = <48000000>;
+ status = "okay";
reg = <0>;
#address-cells = <1>;

Best Regards,
Yordan

0 Richard McAleer over 9 years ago in reply to Yordan Kovachev

Expert 1485 points

Thanks for the suggestion

- it does not seem to have made any difference though: still nothing in either /dev/ /sys/class/mtd or /proc/mtd

dumping the part of the tree I can see the new property

395-        spi@48030000 {
1396-            compatible = "ti,omap4-mcspi";
1397-            #address-cells = <0x00000001>;
1398-            #size-cells = <0x00000000>;
1399-            reg = <0x48030000 0x000001c1>;
1400-            interrupts = <0x00000041>;
1401-            ti,spi-num-cs = <0x00000002>;
1402:            ti,hwmods = "spi0";
1403-            dmas = <0x0000002d 0x00000011 0x00000000 0x00000003 0x72783000 0x00000005 0x00000003 0x756c7400 0x00000043 0x68403000 0x6d696372 0x6d323570>;
1404-            dma-names = "tx0", "rx0", "tx1", "rx1";
1405-            status = "okay";
1406-            pinctrl-names = "default";
1407-            pinctrl-0 = <0x00000043>;
1408-            spi-flash@0 {
1409-                compatible = "micron,n25q256a", "m25p80";
1410-                spi-max-frequency = <0x02dc6c00>;
1411-                status = "okay";
1412-                reg = <0x00000000>;
1413-                #address-cells = <0x00000001>;
1414-                #size-cells = <0x00000001>;

Looking through the code I notice mention of "m25p80" as a compatible and use of "jedec": I'll try and dig around here.

I also notice that modprobe does not find dependencies for "m25p80"

Thanks again

Richard

0 Richard McAleer over 9 years ago in reply to Richard McAleer

Expert 1485 points

it appears the required binding these days looks like:

&spi0 {
    status = "okay";
	pinctrl-names = "default";
	pinctrl-0 = <&spi0_pins>;

	spi-flash@0 {
		compatible = "micron,n25q256a","jedec,spi-nor";  //<---- n.b. this
		spi-max-frequency = <48000000>;
		status = "okay";

This can be found in the bindings documentation of the source code; (these docs will likely be up to date).

all the best

- Richard

0 Yordan Kovachev over 9 years ago in reply to Richard McAleer

TI__Guru**** 161600 points

Thanks for updating the thread.

Best Regards,
Yordan

Processors

Processors forum

Linux/AM3352: m25p80 flash chip not seen in kernel but found in u-boot