rp2040: add version check for RP2040-E5

src/machine/machine_rp2040.go

@@ -4,6 +4,7 @@ package machine
 
 import (
 	"device/rp"
+	"unsafe"
 )
 
 const deviceName = rp.Device
@@ -96,3 +97,20 @@ func CurrentCore() int {
 
 // NumCores returns number of cores available on the device.
 func NumCores() int { return 2 }
+
+// ChipVersion returns the version of the chip. 1 is returned for B0 and B1
+// chip.
+func ChipVersion() uint8 {
+	const (
+		SYSINFO_BASE                  = 0x40000000
+		SYSINFO_CHIP_ID_OFFSET        = 0x00000000
+		SYSINFO_CHIP_ID_REVISION_BITS = 0xf0000000
+		SYSINFO_CHIP_ID_REVISION_LSB  = 28
+	)
+
+	// First register of sysinfo is chip id
+	chipID := *(*uint32)(unsafe.Pointer(uintptr(SYSINFO_BASE + SYSINFO_CHIP_ID_OFFSET)))
+	// Version 1 == B0/B1
+	version := (chipID & SYSINFO_CHIP_ID_REVISION_BITS) >> SYSINFO_CHIP_ID_REVISION_LSB
+	return uint8(version)
+}

src/machine/machine_rp2040_usb_fix_usb_device_enumeration.go

@@ -10,9 +10,20 @@ import (
 // https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2_common/pico_fix/rp2040_usb_device_enumeration/rp2040_usb_device_enumeration.c
 func fixRP2040UsbDeviceEnumeration() {
 
+	// Actually check for B0/B1 h/w
+	if ChipVersion() == 1 {
+		// After coming out of reset, the hardware expects 800us of LS_J (linestate J) time
+		// before it will move to the connected state. However on a hub that broadcasts packets
+		// for other devices this isn't the case. The plan here is to wait for the end of the bus
+		// reset, force an LS_J for 1ms and then switch control back to the USB phy. Unfortunately
+		// this requires us to use GPIO15 as there is no other way to force the input path.
+		// We only need to force DP as DM can be left at zero. It will be gated off by GPIO
+		// logic if it isn't func selected.
+
 		// Wait SE0 phase will call force ls_j phase which will call finish phase
 		hw_enumeration_fix_wait_se0()
 	}
+}
 
 func hw_enumeration_fix_wait_se0() {
 	// Wait for SE0 to end (i.e. the host to stop resetting). This reset can last quite long.