Add RP2350 support (#4459)

machine/rp2350: add support

* add linker scripts for rp2350
* add bootloader
* begin melding rp2040 and rp2350 APIs
* add UART
* add rp2350 boot patching
* Fix RP2350 memory layout (#4626)
* Remove rp2040-style second stage bootloader.
* Add 'minimum viable' IMAGE_DEF embedded block
* Create a pico2 specific target
* Implement rp2350 init, clock, and uart support
* Merge rp2 reset code back together
* Separate chip-specific clock definitions
* Clear pad isolation bit on rp2350
* Init UART in rp2350 runtime
* Correct usb/serial initialization order
* Implement jump-to-bootloader
* test: add pico2 to smoketests

---------

Signed-off-by: deadprogram <ron@hybridgroup.com>
Co-authored-by: Matthew Mets <matt.mets@cibomahto.com>
Co-authored-by: Matt Mets <matt@blinkinlabs.com>
Co-authored-by: deadprogram <ron@hybridgroup.com>

builder/build.go

@@ -822,6 +822,12 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 					return fmt.Errorf("could not modify stack sizes: %w", err)
 				}
 			}
+
+			// Apply patches of bootloader in the order they appear.
+			if len(config.Target.BootPatches) > 0 {
+				err = applyPatches(result.Executable, config.Target.BootPatches)
+			}
+
 			if config.RP2040BootPatch() {
 				// Patch the second stage bootloader CRC into the .boot2 section
 				err = patchRP2040BootCRC(result.Executable)
@@ -1434,6 +1440,23 @@ func printStacks(calculatedStacks []string, stackSizes map[string]functionStackS
 	}
 }
 
+func applyPatches(executable string, bootPatches []string) (err error) {
+	for _, patch := range bootPatches {
+		switch patch {
+		case "rp2040":
+			err = patchRP2040BootCRC(executable)
+		// case "rp2350":
+		// 	err = patchRP2350BootIMAGE_DEF(executable)
+		default:
+			err = errors.New("undefined boot patch name")
+		}
+		if err != nil {
+			return fmt.Errorf("apply boot patch %q: %w", patch, err)
+		}
+	}
+	return nil
+}
+
 // RP2040 second stage bootloader CRC32 calculation
 //
 // Spec: https://datasheets.raspberrypi.org/rp2040/rp2040-datasheet.pdf
@@ -1445,7 +1468,7 @@ func patchRP2040BootCRC(executable string) error {
 	}
 
 	if len(bytes) != 256 {
-		return fmt.Errorf("rp2040 .boot2 section must be exactly 256 bytes")
+		return fmt.Errorf("rp2040 .boot2 section must be exactly 256 bytes, got %d", len(bytes))
 	}
 
 	// From the 'official' RP2040 checksum script:
@@ -1484,3 +1507,10 @@ func lock(path string) func() {
 
 	return func() { flock.Close() }
 }
+
+func b2u8(b bool) uint8 {
+	if b {
+		return 1
+	}
+	return 0
+}