[U-Boot, v6, 1/1] misc: fs_loader: Add request_firmware_into_buf_via_script() for flexible firmware loading via U-Boot script

[Marek Vasut]

On 8/17/25 5:02 PM, Lucien.Jheng wrote:
> This commit introduces a new API,
> request_firmware_into_buf_via_script(), to the fs_loader framework.
> This function allows firmware to be loaded into memory using
> a user-defined U-Boot script, providing greater flexibility for
> firmware loading scenarios that cannot be handled by static file
> paths or device/partition selection alone.
> 
> Key features:
> - The API runs a specified U-Boot script (by name), which is responsible
>    for loading the firmware into memory by any means (e.g., load from MMC, USB, network, etc.).
> - The script must set two environment variables: 'fw_addr'
>    (the memory address where the firmware is loaded) and
>    'fw_size' (the size of the firmware in bytes).
> - The function validates these variables, copies the firmware into a newly
>    allocated buffer (using memdup), and returns the pointer
>    via the provided double pointer argument.
> - The maximum allowed firmware size is checked to prevent buffer overflows.
> - The environment variables are cleared after use to avoid stale data.
> - Detailed error messages are provided for all failure conditions to aid debugging.
> 
> Usage example:
> 1. Define a U-Boot script in the environment that loads the firmware
>     and sets the required variables:
>     => env set my_fw_script 'load mmc 0:1 ${loadaddr} firmware.bin &&
>     env set fw_addr ${loadaddr} && env set fw_size ${filesize}'
> 
> 2. In your code, call the new API:
>     void *fw_buf = NULL;
>     int ret = request_firmware_into_buf_via_script(&fw_buf, 0x46000000, "my_fw_script");
>     if (ret < 0)
> 		return ret;
> 
> This approach allows board integrators and users to customize the firmware
> loading process without modifying the source code,
> simply by changing the script in the U-Boot environment.
> 
> Signed-off-by: Lucien.Jheng <lucienzx159 at gmail.com>

Reviewed-by: Marek Vasut <marek.vasut+renesas at mailbox.org>

Thank you for all this hard work.