Add Wi-Fi firmware partition support for Pico 2 W

[will-v-pi]

This adds the ability to store and load the Wi-Fi firmware for Pico 2 W in a partition. It can be enabled by adding pico_use_partition_firmware(<exe_name>) to your CMakeLists.txt, which will embed a compatible partition table in the binary, and output lots of firmware UF2s to use (all called <exe_name>_firmware_..._.uf2, eg ..._firmware_w for Wi-Fi only, ..._firmware_wb for Wi-Fi and Bluetooth, ..._firmware_w_tbyb for TBYB). You can also create your own partition table and use that.

A Wi-Fi firmware partition is detected as having the ID 0x123456789abcdef0, and the UF2 family_is for Wi-Fi firmware blobs is 0x12345678 - these should probably both be changed to something else before merging? The default firmware partition starts at 3500K into the flash - should this be changed to depend on PICO_FLASH_SIZE_BYTES? The default firmware partition is also duplicated with A/B partitions in the same location in flash - this is required to ensure a signature check is performed before loading the Wi-Fi firmware, as there's no way to call the bootrom to check the signature of a single partition (unless chaining into it), you can only call pick_ab_partition.

The Wi-Fi firmware blob is marked in it's image_def as an RP2350 Risc-V executable, and the partition is marked as ignored_during_riscv_boot - this ensures that it can work with TBYB (as TBYB only works for executable image_defs), and that signature checks are performed before loading the firmware when Secure Boot is enabled (because signature checks are performed for all executable image_defs in a partition that is not marked ignored_during_arm_boot). This is slightly clunky, but seems to work robustly.

Supercedes #1850, as it now includes that function in this PR, and shows a use for it.

[lurch]

pinging @peterharperuk as he did a lot of the Wifi-related stuff for Pico 1.

[peterharperuk]

Works nicely. I think we need to fix the Pico W (rp2040) build errors in src/rp2_common/pico_cyw43_driver/cyw43_driver.c
It would be nice if it gave an error if you're a numpty like me and put pico_use_partition_firmware after pico_add_extra_outputs, but that could be improved later?

[will-v-pi]

It would be nice if it gave an error if you're a numpty like me and put pico_use_partition_firmware after pico_add_extra_outputs, but that could be improved later?

Have added in separate PR #2054

[will-v-pi]

I think we need to fix the Pico W (rp2040) build errors in src/rp2_common/pico_cyw43_driver/cyw43_driver.c

I've added a check that it's not RP2040 in the CMake function, so it'll throw a fatal error at that point if you try to build a binary with pico_use_partition_firmware for RP2040

[armandomontanez]

If the Bazel checks are getting in your way, you can add the two new files to a filegroup (which will silence the error) and file an issue+leave a TODO to support this in Bazel and assign it to me.

[peterharperuk]

Tested this and it seems good.

[will-v-pi]

If the Bazel checks are getting in your way, you can add the two new files to a filegroup (which will silence the error) and file an issue+leave a TODO to support this in Bazel and assign it to me.

Thanks, have done - I couldn't actually assign the issue to you, but have tagged you in it

[lurch]

A Wi-Fi firmware partition is detected as having the ID 0x123456789abcdef0, and the UF2 family_is for Wi-Fi firmware blobs is 0x12345678 - these should probably both be changed to something else before merging?

Is that still going to be happening? I guess choosing randomly-generated IDs is much less likely to produce an accidental collision than a "nice" ID like 0x123456789abcdef0 ? And should those IDs be added to a header-file, to allow other UF2s to make use of this Wi-Fi firmware partition?

[will-v-pi]

A Wi-Fi firmware partition is detected as having the ID 0x123456789abcdef0, and the UF2 family_is for Wi-Fi firmware blobs is 0x12345678 - these should probably both be changed to something else before merging?

Is that still going to be happening? I guess choosing randomly-generated IDs is much less likely to produce an accidental collision than a "nice" ID like 0x123456789abcdef0 ? And should those IDs be added to a header-file, to allow other UF2s to make use of this Wi-Fi firmware partition?

Yes - I was looking for ideas. We could go with 0x776966696669726d (hex for wififirm) for the partition ID, and just use the data family_id we already have?

[lurch]

This doxygen mentions both rom_pick_ab_partition and pick_ab_partition - are they referring to the same function or are they different?

[will-v-pi]

rom_… is the SDK function wrapper for the pick_ab_partition function - so I was using that to refer to it in the SDK (ie the function this calls internally, and where more docs are), but using pick_ab_partition to refer to the behaviour of the underlying bootrom function

[lurch]

Yes - I was looking for ideas. We could go with 0x776966696669726d (hex for wififirm) for the partition ID, and just use the data family_id we already have?

I've got no opinions on this so it's probably something that you and @peterharperuk ought to decide. Would MicroPython be able to use the same Wifi firmware partition as C-SDK code? (or is that another one of my stupidly naive questions? 😆 )

[will-v-pi]

I've noticed an issue with the Risc-V build of the firmware UF2 - for some reason the compilation is putting a programme header in the ELF with offset of 0x0000 in the file loading to 0x1ffff000, when the Arm compiler correctly puts this at offset 0x1000 in the file loading to 0x20000000. @Wren6991 or @kilograham any ideas why the Arm and Risc-V compilers might be compiling the wifi_firmware.S file differently?

[will-v-pi]

I've now got it working for Risc-V by storing copies of the firmware ELFs in the SDK, and then copying those into the build when necessary. It also needs increased bootrom stack size. This is tested and working fine.

However, I'm not sure if this is actually a solution that we want to put in the 2.1.0 SDK release, so it might be best if we don't merge this for 2.1.0 and I can investigate further to fix the Risc-V firmware build?

[richard9999999999]

I see that default firmware partition ID is defined as follows:
#define CYW43_FIRMWARE_PARTITION_ID 0x776966696669726d // wififirm
SDK uses this value as default to find the partition

..Also in pt.json, this long value is used
"id": "0x776966696669726d",

However when I check by picotool, I see following number set as partition ID:

 partition 1 (A):       0036b000->003a7000 S(rw) NSBOOT(rw) NS(rw), id=000000006669726d, "Wi-Fi Firmware", uf2 { data },
                        arm_boot 1, riscv_boot 0

So upper 32 bits are zeros..
And I need to set this truncated value to CYW43_FIRMWARE_PARTITION_ID to get it working.

Did I miss something?

[richard9999999999]

One more note:

function(pico_use_wifi_firmware_partition TARGET)
        if (PICO_PLATFORM STREQUAL "rp2040")
                message(FATAL_ERROR "RP2040 does not support storing wi-fi firmware in partitions")
        endif()
        target_compile_definitions(${TARGET} PRIVATE CYW43_USE_FIRMWARE_PARTITION=1)
        pico_embed_pt_in_binary(${TARGET} ${PICO_CYW43_DRIVER_CURRENT_PATH}/wifi_pt.json)

seems like that partitioning of binary is always done according wifi_pt.json file. In many cases user prefers to have his own partitioning (when e.g. custom bootloader is used). Could'n this be done via preprocessor macro define e.g. something like "CYW43_EMBED_FIRMWARE_PARTITION=0"?