Re: [PATCH 2/3] ARM: stm32mp: bbu: add NOR flash FIP update handler

[Sohaib Mohamed <sohaib.amhmd@gmail.com>]

On Mon, Dec 01, 2025 at 11:38:18AM +0100, Sascha Hauer wrote:
> On Fri, Nov 28, 2025 at 01:51:18AM +0100, Sohaib Mohamed wrote:
> > Add support for updating STM32MP1 bootloader in NOR flash. The handler
> > automatically detects FIP location (256K or 512K offset) and flashes
>
> The "or 512K offset" part isn't implemented, right?

You're correct. Offset 512K is actually the default location for FIP
images in NOR flash layout. I will clarify this in the commit message.

>
> > FSBL at offset 0 and FIP at offset 512K. FIP is truncated if it exceeds
> > available space.
> >
> > The handler detects the FIP location within the image (at either 256K
> > or 512K offset) and flashes components to their appropriate locations:
> > - FSBL at offset 0 (first 256K)
> > - FIP at offset 512K (remainder of flash)
> >
> > When flashing from eMMC boot partitions to NOR, the FIP is truncated if
> > needed since eMMC boot partitions are typically larger than available
> > NOR flash space.
>
> I guess you mean that not the FIP image is truncated, but the input
> image (/dev/mmcx.boot) is truncated to the actual FIP image size.
>
> But like Ahmad I can't find this part implemented. Should we just drop
> this sentence for now?
>
> Sascha
>
> >
> > Signed-off-by: Sohaib Mohamed <sohaib.amhmd@gmail.com>
> > ---
> >  arch/arm/mach-stm32mp/bbu.c | 77 +++++++++++++++++++++++++++++++++++++++++++++
> >  include/mach/stm32mp/bbu.h  | 10 ++++++
> >  2 files changed, 87 insertions(+)
> >
> > diff --git a/arch/arm/mach-stm32mp/bbu.c b/arch/arm/mach-stm32mp/bbu.c
> > index 07b5111341..e8d0138cc7 100644
> > --- a/arch/arm/mach-stm32mp/bbu.c
> > +++ b/arch/arm/mach-stm32mp/bbu.c
> > @@ -193,3 +193,80 @@ int stm32mp_bbu_mmc_fip_register(const char *name,
> >
> >  	return ret;
> >  }
> > +
> > +static int stm32mp_bbu_nor_fip_handler(struct bbu_handler *handler,
> > +			 struct bbu_data *data)
> > +{
> > +	struct bbu_data *fsbl_data, *fip_data;
> > +	enum filetype filetype;
> > +	int ret;
> > +
> > +	filetype = file_detect_type(data->image, data->len);
> > +	if (filetype == filetype_fip) {
> > +		pr_debug("Flashing FIP at offset 512K\n");
> > +		return bbu_flash(data, SZ_512K);
> > +	}
> > +
> > +	if (filetype != filetype_stm32_image_fsbl_v1) {
> > +		if (!bbu_force(data, "incorrect image type. Expected: %s, got %s",
> > +				file_type_to_string(filetype_stm32_image_fsbl_v1),
> > +				file_type_to_string(filetype)))
> > +			return -EINVAL;
> > +
> > +		/* Force: Let's assume it's an FSBL and flash anyway */
> > +	}
> > +
> > +	if (data->len > SZ_256K)
> > +		filetype = file_detect_type(data->image + SZ_256K,
> > +					    data->len - SZ_256K);
> > +	else
> > +		filetype = filetype_unknown;
> > +
> > +	/* Not an eMMC image, just flash 1:1 */
> > +	if (filetype != filetype_fip) {
> > +		pr_debug("Flashing FSBL at offset 0\n");
> > +		return bbu_flash(data, 0);
> > +	}
> > +
> > +	/* On SPI-NOR, offset 256K is FSBL2. If we get a FIP image there
> > +	 * instead, let's assume that's an eMMC boot partition image
> > +	 * and flash the FSBL to offset 0 and the remainder to offset 512K
> > +	 */
> > +
> > +	pr_debug("Flashing FSBL at offset 0\n");
> > +	fsbl_data = data;
> > +	fsbl_data->image = data->image;
> > +	fsbl_data->len = SZ_256K;
> > +
> > +	ret = bbu_flash(fsbl_data, 0);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	pr_debug("Flashing FIP from file offset 256K at offset 512K\n");
> > +	fip_data = data;
> > +	fip_data->image = data->image + SZ_256K;
> > +	fip_data->len = data->len - SZ_256K;
> > +
> > +	return bbu_flash(fip_data, SZ_512K);
> > +}
> > +
> > +int stm32mp_bbu_nor_fip_register(const char *name,
> > +				 const char *devicefile,
> > +				 unsigned long flags)
> > +{
> > +	struct stm32mp_bbu_handler *priv;
> > +	int ret;
> > +
> > +	priv = xzalloc(sizeof(*priv));
> > +
> > +	priv->handler.flags = flags;
> > +	priv->handler.devicefile = devicefile;
> > +	priv->handler.name = name;
> > +	priv->handler.handler = stm32mp_bbu_nor_fip_handler;
> > +
> > +	ret = bbu_register_handler(&priv->handler);
> > +	if (ret)
> > +		free(priv);
> > +
> > +	return ret;
> > +}
> > diff --git a/include/mach/stm32mp/bbu.h b/include/mach/stm32mp/bbu.h
> > index 233bcf6478..87b29f1527 100644
> > --- a/include/mach/stm32mp/bbu.h
> > +++ b/include/mach/stm32mp/bbu.h
> > @@ -10,6 +10,9 @@
> >  int stm32mp_bbu_mmc_fip_register(const char *name, const char *devicefile,
> >  				 unsigned long flags);
> >
> > +int stm32mp_bbu_nor_fip_register(const char *name, const char *devicefile,
> > +				 unsigned long flags);
> > +
> >  #else
> >
> >  static inline int stm32mp_bbu_mmc_fip_register(const char *name,
> > @@ -19,6 +22,13 @@ static inline int stm32mp_bbu_mmc_fip_register(const char *name,
> >  	return -ENOSYS;
> >  }
> >
> > +static inline int stm32mp_bbu_nor_fip_register(const char *name,
> > +					       const char *devicefile,
> > +					       unsigned long flags)
> > +{
> > +	return -ENOSYS;
> > +}
> > +
> >  #endif
> >
> >  #endif /* MACH_STM32MP_BBU_H_ */
> >
> > --
> > 2.43.0
> >
> >
>
> --
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