[U-Boot, v1, 1/1] misc: fs_loader: Add request_firmware_into_buf_via_env API for environment-based firmware loading

[Tom Rini]

On Sun, Jul 20, 2025 at 10:47:50PM +0200, Marek Vasut wrote:
> On 7/20/25 5:04 PM, Lucien.Jheng wrote:
> > This commit adds request_firmware_into_buf_via_env() to the fs_loader driver,
> > enabling firmware loading into a buffer
> > using environment variables for path and size.
> > It supports multiple entries via indexed variable names
> > (e.g., "fw_dir0", "fw_size0").
> > This provides flexible, scriptable firmware loading without hardcoded details.
> > 
> > Signed-off-by: Lucien.Jheng <lucienzx159 at gmail.com>
> > ---
> > Change log:
> > - Re-sending as previous version and add more maintainers to review.
> > 
> >   drivers/misc/fs_loader.c | 59 ++++++++++++++++++++++++++++++++++++++++
> >   include/fs_loader.h      | 18 ++++++++++++
> >   2 files changed, 77 insertions(+)
> > 
> > diff --git a/drivers/misc/fs_loader.c b/drivers/misc/fs_loader.c
> > index 66803f4b997..a4f4448f5cc 100644
> > --- a/drivers/misc/fs_loader.c
> > +++ b/drivers/misc/fs_loader.c
> > @@ -228,6 +228,65 @@ int request_firmware_into_buf(struct udevice *dev,
> >   	return ret;
> >   }
> > 
> > +/**
> > + * request_firmware_into_buf_via_env - Load firmware using environment variables.
> > + * @dev: An instance of a driver.
> > + * @buf: Address of buffer to load firmware into.
> > + * @offset: Offset of a file for start reading into buffer.
> > + * @fw_index: Index of the firmware entry to load.
> > + *
> > + * This function loads firmware into the provided buffer using environment
> > + * variables to determine the firmware file path, address, and size. It supports
> > + * multiple firmware entries by using indexed environment variable names such as
> > + * "fw_dir0", "fw_size0", etc.
> 
> To make this really scriptable, this code has to run a script which does the
> firmware loading and then points the U-Boot code to the buffer with data in
> it.
> 
> Instead of "fw_index", use "char *script_name" or some such. Then, run the
> script. The script should set up two environment variables, call them e.g.
> "fw_addr" and "fw_size" or some such . Then, this code should read the two
> environment variables, validate them, and possibly copy their content into
> $buf . Finally, the code should always unset fw_addr and fw_size .
> 
> Note that request_firmware_into_buf_via_env() should also have 'size'
> parameter which describes the maximum size of loaded firmware, so the code
> could verify whether the copy of firmware into $buf would write past the
> buffer and prevent that.

And for v4, can we please put this patch and the patch using it in the
same series? I see there's some feedback right now from Frank on the
other patch about how maybe this part should be implemented.

-- 
Tom
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