targets,runtime,machine: add support for the stm32f469-disco board

The LEDs and button work; I haven't tested the SPI and I2C
configuration.

src/machine/board_stm32f469disco.go

@@ -0,0 +1,79 @@
+// +build stm32f469disco
+
+package machine
+
+import (
+	"device/stm32"
+	"runtime/interrupt"
+)
+
+const (
+	LED         = LED_BUILTIN
+	LED1        = LED_GREEN
+	LED2        = LED_ORANGE
+	LED3        = LED_RED
+	LED4        = LED_BLUE
+	LED_BUILTIN = LED_GREEN
+	LED_GREEN   = PG6
+	LED_ORANGE  = PD4
+	LED_RED     = PD5
+	LED_BLUE    = PK3
+)
+
+const (
+	BUTTON = PA0
+)
+
+// UART pins
+const (
+	UART_TX_PIN = PB10
+	UART_RX_PIN = PB11
+)
+
+var (
+	UART3  = &_UART3
+	_UART3 = UART{
+		Buffer:            NewRingBuffer(),
+		Bus:               stm32.USART3,
+		TxAltFuncSelector: AF7_USART1_2_3,
+		RxAltFuncSelector: AF7_USART1_2_3,
+	}
+	DefaultUART = UART3
+)
+
+// set up RX IRQ handler. Follow similar pattern for other UARTx instances
+func init() {
+	UART3.Interrupt = interrupt.New(stm32.IRQ_USART3, _UART3.handleInterrupt)
+}
+
+// SPI pins
+const (
+	SPI1_SCK_PIN = PA5
+	SPI1_SDI_PIN = PA6
+	SPI1_SDO_PIN = PA7
+	SPI0_SCK_PIN = SPI1_SCK_PIN
+	SPI0_SDI_PIN = SPI1_SDI_PIN
+	SPI0_SDO_PIN = SPI1_SDO_PIN
+)
+
+// Since the first interface is named SPI1, both SPI0 and SPI1 refer to SPI1.
+// TODO: implement SPI2 and SPI3.
+var (
+	SPI0 = SPI{
+		Bus:             stm32.SPI1,
+		AltFuncSelector: AF5_SPI1_SPI2,
+	}
+	SPI1 = &SPI0
+)
+
+const (
+	I2C0_SCL_PIN = PB6
+	I2C0_SDA_PIN = PB9
+)
+
+var (
+	I2C0 = &I2C{
+		Bus:             stm32.I2C1,
+		AltFuncSelector: AF4_I2C1_2_3,
+	}
+)

src/machine/machine_stm32f4.go

@@ -616,16 +616,6 @@ func initRNG() {
 	stm32.RNG.CR.SetBits(stm32.RNG_CR_RNGEN)
 }
 
-func CPUFrequency() uint32 {
-	return 168000000
-}
-
-// Internal use: configured speed of the APB1 and APB2 timers, this should be kept
-// in sync with any changes to runtime package which configures the oscillators
-// and clock frequencies
-const APB1_TIM_FREQ = 42000000 * 2
-const APB2_TIM_FREQ = 84000000 * 2
-
 // Alternative peripheral pin functions
 const (
 	AF0_SYSTEM                = 0

src/machine/machine_stm32f40x.go

@@ -0,0 +1,15 @@
+//go:build stm32f4 && (stm32f405 || stm32f407)
+// +build stm32f4
+// +build stm32f405 stm32f407
+
+package machine
+
+func CPUFrequency() uint32 {
+	return 168000000
+}
+
+// Internal use: configured speed of the APB1 and APB2 timers, this should be kept
+// in sync with any changes to runtime package which configures the oscillators
+// and clock frequencies
+const APB1_TIM_FREQ = 42000000 * 2
+const APB2_TIM_FREQ = 84000000 * 2

src/machine/machine_stm32f469.go

@@ -0,0 +1,14 @@
+//go:build stm32f4 && stm32f469
+// +build stm32f4,stm32f469
+
+package machine
+
+func CPUFrequency() uint32 {
+	return 180000000
+}
+
+// Internal use: configured speed of the APB1 and APB2 timers, this should be kept
+// in sync with any changes to runtime package which configures the oscillators
+// and clock frequencies
+const APB1_TIM_FREQ = 45000000 * 2
+const APB2_TIM_FREQ = 90000000 * 2