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

[Lucien.Jheng]

Marek Vasut 於 2025/8/18 上午 07:00 寫道:
> 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.

Hi Marek

Thank you for your detailed review and suggestions.