targets: add implementation for Tillitis TKey device (#4631)

* initial implementation for Tillitis TKey device
* add UART implementation for TKey
* add Pin interface implementation for TKey touch sensor
* add RNG interface implementation for TKey
* add helpful machine package functions to return identifiers such as name and version for TKey
* use built-in timer for sleep timing on TKey
* modify UART implementation for TKey to implement Serialer interface
* implement BLAKE2s ROM function call for TKey device
* handle abort by triggering TKey device fault using illegal instruction to halt CPU
* simplify TKey implementation by inheriting from existing riscv32 target
* return error for trying to configure invalid baudrates on UART
* add tkey to builder test
* be very specific for features passed to LLVM for specific config in use for TKey
* handle feedback items from TKey device code review

Signed-off-by: deadprogram <[email protected]>

8 files changed, 523 insertions, 3 deletions

diff --git a/src/crypto/rand/rand_baremetal.go b/src/crypto/rand/rand_baremetal.go
index 15fc916ca..30b2c3b23 100644
--- a/src/crypto/rand/rand_baremetal.go
+++ b/src/crypto/rand/rand_baremetal.go
@@ -1,4 +1,4 @@
-//go:build nrf || (stm32 && !(stm32f103 || stm32l0x1)) || (sam && atsamd51) || (sam && atsame5x) || esp32c3
+//go:build nrf || (stm32 && !(stm32f103 || stm32l0x1)) || (sam && atsamd51) || (sam && atsame5x) || esp32c3 || tkey
 
 // If you update the above build constraint, you'll probably also need to update
 // src/runtime/rand_hwrng.go.
diff --git a/src/device/tkey/tkey.go b/src/device/tkey/tkey.go
new file mode 100644
index 000000000..89a370414
--- /dev/null
+++ b/src/device/tkey/tkey.go
@@ -0,0 +1,139 @@
+//go:build tkey
+
+// Hand written file based on https://github.com/tillitis/tkey-libs/blob/main/include/tkey/tk1_mem.h
+
+package tkey
+
+import (
+	"runtime/volatile"
+	"unsafe"
+)
+
+// Peripherals
+var (
+	TRNG = (*TRNG_Type)(unsafe.Pointer(TK1_MMIO_TRNG_BASE))
+
+	TIMER = (*TIMER_Type)(unsafe.Pointer(TK1_MMIO_TIMER_BASE))
+
+	UDS = (*UDS_Type)(unsafe.Pointer(TK1_MMIO_UDS_BASE))
+
+	UART = (*UART_Type)(unsafe.Pointer(TK1_MMIO_UART_BASE))
+
+	TOUCH = (*TOUCH_Type)(unsafe.Pointer(TK1_MMIO_TOUCH_BASE))
+
+	TK1 = (*TK1_Type)(unsafe.Pointer(TK1_MMIO_TK1_BASE))
+)
+
+// Memory sections
+const (
+	TK1_ROM_BASE uintptr = 0x00000000
+
+	TK1_RAM_BASE uintptr = 0x40000000
+
+	TK1_MMIO_BASE uintptr = 0xc0000000
+
+	TK1_MMIO_TRNG_BASE uintptr = 0xc0000000
+
+	TK1_MMIO_TIMER_BASE uintptr = 0xc1000000
+
+	TK1_MMIO_UDS_BASE uintptr = 0xc2000000
+
+	TK1_MMIO_UART_BASE uintptr = 0xc3000000
+
+	TK1_MMIO_TOUCH_BASE uintptr = 0xc4000000
+
+	TK1_MMIO_FW_RAM_BASE uintptr = 0xd0000000
+
+	TK1_MMIO_TK1_BASE uintptr = 0xff000000
+)
+
+// Memory section sizes
+const (
+	TK1_RAM_SIZE uintptr = 0x20000
+
+	TK1_MMIO_SIZE uintptr = 0x3fffffff
+)
+
+type TRNG_Type struct {
+	_       [36]byte
+	STATUS  volatile.Register32
+	_       [88]byte
+	ENTROPY volatile.Register32
+}
+
+type TIMER_Type struct {
+	_         [32]byte
+	CTRL      volatile.Register32
+	STATUS    volatile.Register32
+	PRESCALER volatile.Register32
+	TIMER     volatile.Register32
+}
+
+type UDS_Type struct {
+	_    [64]byte
+	DATA [8]volatile.Register32
+}
+
+type UART_Type struct {
+	_         [128]byte
+	RX_STATUS volatile.Register32
+	RX_DATA   volatile.Register32
+	RX_BYTES  volatile.Register32
+	_         [116]byte
+	TX_STATUS volatile.Register32
+	TX_DATA   volatile.Register32
+}
+
+type TOUCH_Type struct {
+	_      [36]byte
+	STATUS volatile.Register32
+}
+
+type TK1_Type struct {
+	NAME0         volatile.Register32
+	NAME1         volatile.Register32
+	VERSION       volatile.Register32
+	_             [16]byte
+	SWITCH_APP    volatile.Register32
+	_             [4]byte
+	LED           volatile.Register32
+	GPIO          volatile.Register16
+	APP_ADDR      volatile.Register32
+	APP_SIZE      volatile.Register32
+	BLAKE2S       volatile.Register32
+	_             [72]byte
+	CDI_FIRST     [8]volatile.Register32
+	_             [32]byte
+	UDI_FIRST     [2]volatile.Register32
+	_             [62]byte
+	RAM_ADDR_RAND volatile.Register16
+	_             [2]byte
+	RAM_DATA_RAND volatile.Register16
+	_             [126]byte
+	CPU_MON_CTRL  volatile.Register16
+	_             [2]byte
+	CPU_MON_FIRST volatile.Register32
+	CPU_MON_LAST  volatile.Register32
+	_             [60]byte
+	SYSTEM_RESET  volatile.Register16
+	_             [66]byte
+	SPI_EN        volatile.Register32
+	SPI_XFER      volatile.Register32
+	SPI_DATA      volatile.Register32
+}
+
+const (
+	TK1_MMIO_TIMER_CTRL_START_BIT = 0
+	TK1_MMIO_TIMER_CTRL_STOP_BIT  = 1
+	TK1_MMIO_TIMER_CTRL_START     = 1 << TK1_MMIO_TIMER_CTRL_START_BIT
+	TK1_MMIO_TIMER_CTRL_STOP      = 1 << TK1_MMIO_TIMER_CTRL_STOP_BIT
+
+	TK1_MMIO_TK1_LED_R_BIT = 2
+	TK1_MMIO_TK1_LED_G_BIT = 1
+	TK1_MMIO_TK1_LED_B_BIT = 0
+
+	TK1_MMIO_TK1_GPIO1_BIT = 0
+	TK1_MMIO_TK1_GPIO2_BIT = 1
+	TK1_MMIO_TK1_GPIO3_BIT = 2
+	TK1_MMIO_TK1_GPIO4_BIT = 3
+)
diff --git a/src/machine/machine_tkey.go b/src/machine/machine_tkey.go
new file mode 100644
index 000000000..78863d845
--- /dev/null
+++ b/src/machine/machine_tkey.go
@@ -0,0 +1,234 @@
+//go:build tkey
+
+package machine
+
+import (
+	"device/tkey"
+	"errors"
+	"strconv"
+)
+
+const deviceName = "TKey"
+
+// GPIO pins modes are only here to match the Pin interface.
+// The actual configuration is fixed in the hardware.
+const (
+	PinOutput PinMode = iota
+	PinInput
+	PinInputPullup
+	PinInputPulldown
+)
+
+const (
+	LED_BLUE  = Pin(tkey.TK1_MMIO_TK1_LED_B_BIT)
+	LED_GREEN = Pin(tkey.TK1_MMIO_TK1_LED_G_BIT)
+	LED_RED   = Pin(tkey.TK1_MMIO_TK1_LED_R_BIT)
+
+	LED = LED_GREEN
+
+	TKEY_TOUCH = Pin(3) // 3 is unused, but we need a value here to match the Pin interface.
+	BUTTON     = TKEY_TOUCH
+
+	GPIO1 = Pin(tkey.TK1_MMIO_TK1_GPIO1_BIT + 8)
+	GPIO2 = Pin(tkey.TK1_MMIO_TK1_GPIO2_BIT + 8)
+	GPIO3 = Pin(tkey.TK1_MMIO_TK1_GPIO3_BIT + 8)
+	GPIO4 = Pin(tkey.TK1_MMIO_TK1_GPIO4_BIT + 8)
+)
+
+var touchConfig, gpio1Config, gpio2Config PinConfig
+
+// No config needed for TKey, just to match the Pin interface.
+func (p Pin) Configure(config PinConfig) {
+	switch p {
+	case BUTTON:
+		touchConfig = config
+
+		// Clear any pending touch events.
+		tkey.TOUCH.STATUS.Set(0)
+	case GPIO1:
+		gpio1Config = config
+	case GPIO2:
+		gpio2Config = config
+	}
+}
+
+// Set pin to high or low.
+func (p Pin) Set(high bool) {
+	switch p {
+	case LED_BLUE, LED_GREEN, LED_RED:
+		if high {
+			tkey.TK1.LED.SetBits(1 << uint(p))
+		} else {
+			tkey.TK1.LED.ClearBits(1 << uint(p))
+		}
+	case GPIO3, GPIO4:
+		if high {
+			tkey.TK1.GPIO.SetBits(1 << uint(p-8))
+		} else {
+			tkey.TK1.GPIO.ClearBits(1 << uint(p-8))
+		}
+	}
+}
+
+// Get returns the current value of a pin.
+func (p Pin) Get() bool {
+	pushed := false
+	mode := PinInput
+
+	switch p {
+	case BUTTON:
+		mode = touchConfig.Mode
+		if tkey.TOUCH.STATUS.HasBits(1) {
+			tkey.TOUCH.STATUS.Set(0)
+			pushed = true
+		}
+	case GPIO1:
+		mode = gpio1Config.Mode
+		pushed = tkey.TK1.GPIO.HasBits(1 << uint(p-8))
+	case GPIO2:
+		mode = gpio2Config.Mode
+		pushed = tkey.TK1.GPIO.HasBits(1 << uint(p-8))
+	case GPIO3, GPIO4:
+		mode = PinOutput
+		pushed = tkey.TK1.GPIO.HasBits(1 << uint(p-8))
+	case LED_BLUE, LED_GREEN, LED_RED:
+		mode = PinOutput
+		pushed = tkey.TK1.LED.HasBits(1 << uint(p))
+	}
+
+	switch mode {
+	case PinInputPullup:
+		return !pushed
+	case PinInput, PinInputPulldown, PinOutput:
+		return pushed
+	}
+
+	return false
+}
+
+type UART struct {
+	Bus *tkey.UART_Type
+}
+
+var (
+	DefaultUART = UART0
+	UART0       = &_UART0
+	_UART0      = UART{Bus: tkey.UART}
+)
+
+// The TKey UART is fixed at 62500 baud, 8N1.
+func (uart *UART) Configure(config UARTConfig) error {
+	if !(config.BaudRate == 62500 || config.BaudRate == 0) {
+		return errors.New("uart: only 62500 baud rate is supported")
+	}
+
+	return nil
+}
+
+// Write a slice of data bytes to the UART.
+func (uart *UART) Write(data []byte) (n int, err error) {
+	for _, c := range data {
+		if err := uart.WriteByte(c); err != nil {
+			return n, err
+		}
+	}
+	return len(data), nil
+}
+
+// WriteByte writes a byte of data to the UART.
+func (uart *UART) WriteByte(c byte) error {
+	for uart.Bus.TX_STATUS.Get() == 0 {
+	}
+
+	uart.Bus.TX_DATA.Set(uint32(c))
+
+	return nil
+}
+
+// Buffered returns the number of bytes buffered in the UART.
+func (uart *UART) Buffered() int {
+	return int(uart.Bus.RX_BYTES.Get())
+}
+
+// ReadByte reads a byte of data from the UART.
+func (uart *UART) ReadByte() (byte, error) {
+	for uart.Bus.RX_STATUS.Get() == 0 {
+	}
+
+	return byte(uart.Bus.RX_DATA.Get()), nil
+}
+
+// DTR is not available on the TKey.
+func (uart *UART) DTR() bool {
+	return false
+}
+
+// RTS is not available on the TKey.
+func (uart *UART) RTS() bool {
+	return false
+}
+
+// GetRNG returns 32 bits of cryptographically secure random data
+func GetRNG() (uint32, error) {
+	for tkey.TRNG.STATUS.Get() == 0 {
+	}
+
+	return uint32(tkey.TRNG.ENTROPY.Get()), nil
+}
+
+// DesignName returns the FPGA design name.
+func DesignName() (string, string) {
+	n0 := tkey.TK1.NAME0.Get()
+	name0 := string([]byte{byte(n0 >> 24), byte(n0 >> 16), byte(n0 >> 8), byte(n0)})
+	n1 := tkey.TK1.NAME1.Get()
+	name1 := string([]byte{byte(n1 >> 24), byte(n1 >> 16), byte(n1 >> 8), byte(n1)})
+
+	return name0, name1
+}
+
+// DesignVersion returns the FPGA design version.
+func DesignVersion() string {
+	version := tkey.TK1.VERSION.Get()
+
+	return strconv.Itoa(int(version))
+}
+
+// CDI returns 8 words of Compound Device Identifier (CDI) generated and written by the firmware when the application is loaded.
+func CDI() []byte {
+	cdi := make([]byte, 32)
+	for i := 0; i < 8; i++ {
+		c := tkey.TK1.CDI_FIRST[i].Get()
+		cdi[i*4] = byte(c >> 24)
+		cdi[i*4+1] = byte(c >> 16)
+		cdi[i*4+2] = byte(c >> 8)
+		cdi[i*4+3] = byte(c)
+	}
+	return cdi
+}
+
+// UDI returns 2 words of Unique Device Identifier (UDI). Only available in firmware mode.
+func UDI() []byte {
+	udi := make([]byte, 8)
+	for i := 0; i < 2; i++ {
+		c := tkey.TK1.UDI_FIRST[i].Get()
+		udi[i*4] = byte(c >> 24)
+		udi[i*4+1] = byte(c >> 16)
+		udi[i*4+2] = byte(c >> 8)
+		udi[i*4+3] = byte(c)
+	}
+	return udi
+}
+
+// UDS returns 8 words of Unique Device Secret. Part of the FPGA design, changed when provisioning a TKey.
+// Only available in firmware mode. UDS is only readable once per power cycle.
+func UDS() []byte {
+	uds := make([]byte, 32)
+	for i := 0; i < 8; i++ {
+		c := tkey.UDS.DATA[i].Get()
+		uds[i*4] = byte(c >> 24)
+		uds[i*4+1] = byte(c >> 16)
+		uds[i*4+2] = byte(c >> 8)
+		uds[i*4+3] = byte(c)
+	}
+	return uds
+}
diff --git a/src/machine/machine_tkey_rom.go b/src/machine/machine_tkey_rom.go
new file mode 100644
index 000000000..bc7162e04
--- /dev/null
+++ b/src/machine/machine_tkey_rom.go
@@ -0,0 +1,59 @@
+//go:build tkey
+
+package machine
+
+/*
+	#define TK1_MMIO_TK1_BLAKE2S 0xff000040
+
+	typedef unsigned char uint8_t;
+	typedef unsigned long uint32_t;
+	typedef unsigned long size_t;
+
+	// blake2s state context
+	typedef struct {
+		uint8_t b[64]; // input buffer
+		uint32_t h[8]; // chained state
+		uint32_t t[2]; // total number of bytes
+		size_t c;      // pointer for b[]
+		size_t outlen; // digest size
+	} blake2s_ctx;
+
+	typedef int (*fw_blake2s_p)(void *out, unsigned long outlen, const void *key,
+		unsigned long keylen, const void *in,
+		unsigned long inlen, blake2s_ctx *ctx);
+
+	int blake2s(void *out, unsigned long outlen, const void *key, unsigned long keylen, const void *in, unsigned long inlen)
+	{
+		fw_blake2s_p const fw_blake2s =
+	    	(fw_blake2s_p) * (volatile uint32_t *)TK1_MMIO_TK1_BLAKE2S;
+		blake2s_ctx ctx;
+
+		return fw_blake2s(out, outlen, key, keylen, in, inlen, &ctx);
+	}
+*/
+import "C"
+import (
+	"errors"
+	"unsafe"
+)
+
+var (
+	ErrBLAKE2sInvalid = errors.New("invalid params for call to BLAKE2s")
+	ErrBLAKE2sFailed  = errors.New("call to BLAKE2s failed")
+)
+
+func BLAKE2s(output []byte, key []byte, input []byte) error {
+	if len(output) == 0 || len(input) == 0 {
+		return ErrBLAKE2sInvalid
+	}
+
+	op := unsafe.Pointer(&output[0])
+	kp := unsafe.Pointer(&key[0])
+	ip := unsafe.Pointer(&input[0])
+
+	if res := C.blake2s(op, C.size_t(len(output)), kp, C.size_t(len(key)), ip, C.size_t(len(input))); res != 0 {
+		return ErrBLAKE2sFailed
+	}
+
+	return nil
+}
diff --git a/src/runtime/rand_hwrng.go b/src/runtime/rand_hwrng.go
index 7154ffd79..2c690b449 100644
--- a/src/runtime/rand_hwrng.go
+++ b/src/runtime/rand_hwrng.go
@@ -1,4 +1,4 @@
-//go:build baremetal && (nrf || (stm32 && !(stm32f103 || stm32l0x1)) || (sam && atsamd51) || (sam && atsame5x) || esp32c3)
+//go:build baremetal && (nrf || (stm32 && !(stm32f103 || stm32l0x1)) || (sam && atsamd51) || (sam && atsame5x) || esp32c3 || tkey)
 
 // If you update the above build constraint, you'll probably also need to update
 // src/crypto/rand/rand_baremetal.go.
diff --git a/src/runtime/rand_norng.go b/src/runtime/rand_norng.go
index e6045008e..a86cdc542 100644
--- a/src/runtime/rand_norng.go
+++ b/src/runtime/rand_norng.go
@@ -1,4 +1,4 @@
-//go:build baremetal && !(nrf || (stm32 && !(stm32f103 || stm32l0x1)) || (sam && atsamd51) || (sam && atsame5x) || esp32c3)
+//go:build baremetal && !(nrf || (stm32 && !(stm32f103 || stm32l0x1)) || (sam && atsamd51) || (sam && atsame5x) || esp32c3 || tkey)
 
 package runtime
 
diff --git a/src/runtime/runtime_tkey.go b/src/runtime/runtime_tkey.go
new file mode 100644
index 000000000..ba8c5e944
--- /dev/null
+++ b/src/runtime/runtime_tkey.go
@@ -0,0 +1,64 @@
+//go:build tkey
+
+// This file implements target-specific things for the TKey.
+
+package runtime
+
+import (
+	"device/tkey"
+	"machine"
+	"runtime/volatile"
+)
+
+type timeUnit int64
+
+//export main
+func main() {
+	preinit()
+	initPeripherals()
+	run()
+	exit(0)
+}
+
+// initPeripherals configures peripherals the way the runtime expects them.
+func initPeripherals() {
+	// prescaler value that results in 0.00001-second timer-ticks.
+	// given an 18 MHz processor, a millisecond is about 18,000 cycles.
+	tkey.TIMER.PRESCALER.Set(18 * machine.MHz / 100000)
+
+	machine.InitSerial()
+}
+
+func putchar(c byte) {
+	machine.Serial.WriteByte(c)
+}
+
+func getchar() byte {
+	for machine.Serial.Buffered() == 0 {
+		Gosched()
+	}
+	v, _ := machine.Serial.ReadByte()
+	return v
+}
+
+func buffered() int {
+	return machine.Serial.Buffered()
+}
+
+var timestamp volatile.Register32
+
+// ticks returns the current value of the timer in ticks.
+func ticks() timeUnit {
+	return timeUnit(timestamp.Get())
+}
+
+// sleepTicks sleeps for at least the duration d.
+func sleepTicks(d timeUnit) {
+	target := uint32(ticks() + d)
+
+	tkey.TIMER.TIMER.Set(uint32(d))
+	tkey.TIMER.CTRL.SetBits(tkey.TK1_MMIO_TIMER_CTRL_START)
+	for tkey.TIMER.STATUS.Get() != 0 {
+	}
+	timestamp.Set(target)
+}
diff --git a/src/runtime/runtime_tkey_baremetal.go b/src/runtime/runtime_tkey_baremetal.go
new file mode 100644
index 000000000..a83bd4408
--- /dev/null
+++ b/src/runtime/runtime_tkey_baremetal.go
@@ -0,0 +1,24 @@
+//go:build tkey && !qemu
+
+package runtime
+
+import "device/riscv"
+
+// ticksToNanoseconds converts ticks (at 18MHz) to 10 µs.
+func ticksToNanoseconds(ticks timeUnit) int64 {
+	return int64(ticks) * 10000
+}
+
+// nanosecondsToTicks converts 10 µs to ticks (at 18MHz).
+func nanosecondsToTicks(ns int64) timeUnit {
+	return timeUnit(ns / 10000)
+}
+
+func exit(code int) {
+	abort()
+}
+
+func abort() {
+	// Force illegal instruction to halt CPU
+	riscv.Asm("unimp")
+}