Can't access QSPI from linux

[jwdonal]

I have a Zynq-7030 device with a QSPI attached in QSPI single mode (S25FL256) on a custom board. I want to be able to flash the QSPI device from within linux using the 'flashcp' command in the MTD utils package but I'm having issues.

Some information:

- QSPI peripheral is enabled in block design Zynq IP core

- Can successfully program QSPI device from within SDK using qspi_single mode

- Zynq has boot mode pins set to boot from QSPI and does successfully launch u-boot from QSPI

- u-boot sees QSPI device and reports: "SF: Detected s25fl256s_64k with page size 256 Bytes, erase size 64 KiB, total 32 MiB"

- u-boot is able to perform all basic operations on the device read/write/erase

- Running Ubuntu 16.04 LTS (Linux 4.9.0-xilinx)

- Have CONFIG_SPI_ZYNQ_QSPI driver enabled (built-in) in kernel

- The default (untouched by me) zynq-7000.dtsi file included with the kernel contains the following:

		qspi: spi@e000d000 {
			clock-names = "ref_clk", "pclk";
			clocks = <&clkc 10>, <&clkc 43>;
			compatible = "xlnx,zynq-qspi-1.0";
			status = "disabled";
			interrupt-parent = <&intc>;
			interrupts = <0 19 4>;
			reg = <0xe000d000 0x1000>;
			#address-cells = <1>;
			#size-cells = <0>;
		};

- I reviewed the above dtsi information and it all seems to check out and match what I can find on various other websites/tutorials and the Zynq TRM.

- In my DTS (which #include's the above dtsi) I have the following:

&qspi {
	u-boot,dm-pre-reloc;
	status = "okay";
	is-dual = <0>;
	num-cs = <1>;
	flash@0 {
		compatible = "s25fl256s1";
		reg = <0x0>;
		spi-max-frequency = <50000000>;
		#address-cells = <1>;
		#size-cells = <1>;
		partition@qspi-boot-bin {
			label = "qspi-boot-bin";
			reg = <0x0 0x2000000>;
		};
	};
};

- I have tried all sorts of various combinations of DTS parameters/values/partitions found on various websites but I still can't see the QSPI device from within linux.

- I have kernel debugging and earlyprintk enabled and I see nothing in the kernel boot log related to any qspi/mtd device. According to this () website I should see something similar to (although not exactly, e.g. different partitions) the following in the kernel boot log:

zynq-qspi e000d000.qspi: master is unqueued, this is deprecated
m25p80 spi0.0: s25fl256s1 (32768 Kbytes)
4 ofpart partitions found on MTD device spi0.0
Creating 4 MTD partitions on "spi0.0":
0x000000000000-0x000000100000 : "qspi-boot"
0x000000100000-0x000000450000 : "qspi-linux"
0x000000450000-0x000000470000 : "qspi-device-tree"
0x000000470000-0x000000d70000 : "qspi-rootfs"
zynq-qspi e000d000.qspi: at 0xE000D000 mapped to 0xE087A000, irq=51

- The kernel boot log reports no errors/warnings of any kind for any peripheral.

- Running 'ls /dev/mtd*' or 'cat /proc/mtd' returns nothing. The Zynq QSPI driver is clearly not loading.

I have never actually had this much trouble trying to get a Zynq peripheral to work. I think I must just be doing something really dumb or missing something very obvious. I've spent several hours trying to debug this already. I could use a fresh pair of eyes. Does anyone have any ideas? It really shouldn't be this hard...it has to be something simple.

[gudishak]

Hi @jwdonal,

I would like to see whether you are using JFFS2 filesystem or initramfs from kernel command line.

Could you please share your complete boot log? 

[gudishak]

@jwdonal,

could you please add compatible name as mentioned below,

compatible = "micron,m25p80"; 

[jwdonal]

I have attached boot log as requested. I also tried adding the compatible line you suggested and it did not make any difference, still no MTD devices being enumerated.

As far as file structure I have kernel/DTB on small FAT partition on eMMC and then root file system on EXT4 partition on eMMC. I did not specifically enable any JFFS anywhere that I know of. I am also not using initramfs. Here is the output of the mount command:

# mount
/dev/mmcblk0p2 on / type ext4 (rw,relatime,data=ordered)
devtmpfs on /dev type devtmpfs (rw,relatime,size=490176k,nr_inodes=122544,mode=755)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd)
configfs on /sys/kernel/config type configfs (rw,relatime)
/dev/mmcblk0p1 on /mnt/mysdcard_fat type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)

Thank you so much for the quick response. I would appreciate it so much if you could help me get this working. It is really annoying me at this point.

[jwdonal]

Here is some more info. I placed debug dev_info() print statements within the 'probe' method of the drivers/spi/spi-zynq-qspi.c source file and it gets all the way through the probe function and returns 0 (success).  So the driver is in the kernel, it is probing, and it is returning success.

But the kernel is not reporting any MTD devices at all. I don't understand what's wrong. I also checked and I have the MTD subsystem enabled in the kernel as well.

  x Symbol: MTD [=y]                                                                                                               x
  x Type  : tristate                                                                                                               x
  x Prompt: Memory Technology Device (MTD) support                                                                                 x
  x   Location:                                                                                                                    x
  x (1) -> Device Drivers                                                                                                          x
  x   Defined at drivers/mtd/Kconfig:1                                                                                             x
  x   Depends on: GENERIC_IO [=y]

There are many other MTD options which are enabled as well. Maybe there is a specific MTD kernel config option that needs to be enabled?

Now that I see that the zynq QSPI kernel driver is indeed probing and returning success I am now at a total loss for what else to try.

[jwdonal · Accepted solution]

HA!! I got it working!! Once I started down the path of thinking "maybe there is something wrong with the MTD subsystem" that lead me to a VERY useful forum post that hadn't popped up in my previous searching!

https://forums.xilinx.com/t5/Embedded-Linux/Linux-kernel-cannot-access-QSPI-MTD/m-p/766109/highlight/true#M19794

All I had to do was enable CONFIG_MTD_M25P80 in the kernel. And like the author in the post above states I too used the "make xilinx_zynq_defconfig" and it does not enable the CONFIG_MTD_M25P80 option by default. That should really be fixed...