On 17-08-2026 17:55, Heinrich Schuchardt wrote:
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.
Tried putting something together in an updated patch. Seems to have some
effect now. Some block device registers now, but there's no working link
to the partitioning:
zynq-uboot> lsblk
Block Driver Devices
-----------------------------
mmc_blk : mmc 0
mtd_blk : mtd 0
ubi_blk : mtd 1
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
blk 0 [ ] mtd_blk | | |-- [email protected]
blk 1 [ ] ubi_blk | | `-- [email protected]
mmc 0 [ + ] arasan_sdhci | |-- mmc@e0100000
blk 2 [ ] 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
zynq-uboot> ls mtd 0
** Bad device specification mtd 0 **
Couldn't find partition mtd 0
--
Mike Looijmans
System Expert
TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands
T: +31 (0) 499 33 69 69
E: [email protected]
W: www.topic.nl
From 2e822bce1ffeba2b0009e886319383e3eb910a1d Mon Sep 17 00:00:00 2001
From: Mike Looijmans <[email protected]>
Date: Tue, 25 Mar 2025 16:03:03 +0100
Subject: [PATCH] spi/sf_probe.c: Register stuff at ubi/mtd in bind
Doesn't work, see mail list
Creates block devices, but they don't work
Have to set CONFIG_SYS_MALLOC_F_LEN=0x900 to prevent allocation error
---
drivers/mtd/spi/sf_probe.c | 27 +++++++++++++++++++++++++++
include/linux/mtd/spi-nor.h | 3 +++
2 files changed, 30 insertions(+)
diff --git a/drivers/mtd/spi/sf_probe.c b/drivers/mtd/spi/sf_probe.c
index 7100b64bf22..6a6fc0a9185 100644
--- a/drivers/mtd/spi/sf_probe.c
+++ b/drivers/mtd/spi/sf_probe.c
@@ -7,14 +7,17 @@
* Copyright (C) 2013 Jagannadha Sutradharudu Teki, Xilinx Inc.
*/
+#include <blk.h>
#include <dm.h>
#include <errno.h>
+#include <linux/mtd/mtd.h>
#include <linux/mtd/spi-nor.h>
#include <log.h>
#include <malloc.h>
#include <spi.h>
#include <spi_flash.h>
#include <spi-mem.h>
+#include <ubi_uboot.h>
#include "sf_internal.h"
@@ -219,6 +222,29 @@ int spi_flash_std_probe(struct udevice *dev)
return spi_flash_probe_slave(flash);
}
+int spi_flash_std_bind(struct udevice *dev)
+{
+#ifndef CONFIG_XPL_BUILD
+ struct spi_flash *flash = dev_get_uclass_priv(dev);
+ int ret;
+
+ if (blk_enabled()) {
+ if (CONFIG_IS_ENABLED(MTD_BLOCK)) {
+ // Workaround for mtd_bid requiring a "**" instead of a "*"
+ flash->mtd_p = &flash->mtd;
+ ret = mtd_bind(dev, &flash->mtd_p);
+ if (ret)
+ return ret;
+ }
+
+ if (CONFIG_IS_ENABLED(UBI_BLOCK))
+ return ubi_bind(dev);
+ }
+#endif
+
+ return 0;
+}
+
static int spi_flash_std_remove(struct udevice *dev)
{
struct spi_flash *flash = dev_get_uclass_priv(dev);
@@ -256,6 +282,7 @@ U_BOOT_DRIVER(jedec_spi_nor) = {
.id = UCLASS_SPI_FLASH,
.of_match = spi_flash_std_ids,
.probe = spi_flash_std_probe,
+ .bind = spi_flash_std_bind,
.remove = spi_flash_std_remove,
.priv_auto = sizeof(struct spi_nor),
.ops = &spi_flash_std_ops,
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 4eef4ab0488..08b318725bf 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -556,6 +556,9 @@ struct spi_flash {
*/
struct spi_nor {
struct mtd_info mtd;
+#ifndef CONFIG_XPL_BUILD
+ struct mtd_info *mtd_p;
+#endif
struct udevice *dev;
struct spi_slave *spi;
const struct flash_info *info;
--
2.43.0
