On 8/17/26 17:00, Mike Looijmans wrote:
What I'm trying to accomplish is to be able to read the kernel directly
from a squashfs partition in SPI NOR flash.
This should have been simple, as SPI-NOR is an MTD device, and MTD_BLOCK
translates that to a block device, and squashfs needs a block device.
The issue is that MTD_BLOCK adds some hooks, in particular "mtd_bind()"
but the only point where that ever gets called is from drivers/mtd/nand/
spi/core.c
So even though one activates CONFIG_MTD_BLOCK, no mtd device or
partition ever gets registered as a block device (unless you happen to
have a spi-nand controller, which, contrary to spi-nor, would be
unsuitable for a squashfs filesystem...)
I tried doing the obvious, that is, copy and adapt the spi-nand code
into the spi-nor driver, see attached patch, but that doesn't have any
effect whatsoever.
I tried similar things a few months ago, and also had a discussion here
on the list, but that sort of faded out without any further results...
spi_flash_std_bind() is called before spi_flash_std_probe(). Setting
plat->mtd in spi_flash_std_probe() will have no effect in the bind method.
The mailing list has moved to [email protected].
Please, use scripts/get_maintainer.pl to find the maintainer of a
specific U-Boot module.
Best regards
Heinrich
Example session:
zynq-uboot> mtd list
SF: Detected n25q256ax1 with page size 256 Bytes, erase size 64 KiB,
total 32 MiB
0x000000000000-0x000000100000 : "qspi-boot-bin"
0x000000100000-0x000002000000 : "qspi-rootfs"
List of MTD devices:
* nor0
- device: flash@0
- parent: spi@e000d000
- driver: jedec_spi_nor
- path: /axi/spi@e000d000/flash@0
- type: NOR flash
- block size: 0x10000 bytes
- min I/O: 0x1 bytes
- 0x000000000000-0x000002000000 : "nor0"
- 0x000000000000-0x000000100000 : "qspi-boot-bin"
- 0x000000100000-0x000002000000 : "qspi-rootfs"
zynq-uboot> lsblk
Block Driver Devices
-----------------------------
mmc_blk : mmc 0
mtd_blk : <none>
ubi_blk : <none>
usb_storage_blk : <none>
zynq-uboot> dm tree
Class Seq Probed Driver Name
-----------------------------------------------------------
root 0 [ + ] root_driver root_driver
simple_bus 0 [ + ] simple_bus |-- axi
gpio 0 [ ] gpio_zynq | |-- gpio@e000a000
i2c 0 [ ] i2c_cdns | |-- i2c@e0004000
i2c 1 [ ] i2c_cdns | |-- i2c@e0005000
gpio 1 [ ] pca953x | | `-- gpio@41
serial 0 [ + ] serial_zynq | |-- serial@e0000000
spi 0 [ + ] zynq_qspi | |-- spi@e000d000
spi_flash 0 [ + ] jedec_spi_nor | | `-- flash@0
mmc 0 [ + ] arasan_sdhci | |-- mmc@e0100000
blk 0 [ ] mmc_blk | | |--
[email protected]
bootdev 0 [ ] mmc_bootdev | | `--
[email protected]
simple_bus 1 [ + ] simple_bus | |-- slcr@f8000000
clk 0 [ + ] zynq_clk | | `-- clkc@100
timer 0 [ + ] arm_twd_timer | |-- timer@f8f00600
usb 0 [ ] ehci_zynq | `-- usb@e0002000
bootstd 0 [ ] bootstd_drv `-- bootstd
bootmeth 0 [ ] bootmeth_extlinux `-- extlinux
