// +build stm32f407

package machine

// Peripheral abstraction layer for the stm32f407

import (
	"device/stm32"
	"runtime/interrupt"
)

func CPUFrequency() uint32 {
	return 168000000
}

//---------- UART related types and code

// UART representation
type UART struct {
	Buffer          *RingBuffer
	Bus             *stm32.USART_Type
	Interrupt       interrupt.Interrupt
	AltFuncSelector stm32.AltFunc
}

// Configure the UART.
func (uart UART) configurePins(config UARTConfig) {
	// enable the alternate functions on the TX and RX pins
	config.TX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTTX}, uart.AltFuncSelector)
	config.RX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTRX}, uart.AltFuncSelector)
}

// UART baudrate calc based on the bus and clockspeed
// NOTE: keep this in sync with the runtime/runtime_stm32f407.go clock init code
func (uart UART) getBaudRateDivisor(baudRate uint32) uint32 {
	var clock uint32
	switch uart.Bus {
	case stm32.USART1, stm32.USART6:
		clock = CPUFrequency() / 2 // APB2 Frequency
	case stm32.USART2, stm32.USART3, stm32.UART4, stm32.UART5:
		clock = CPUFrequency() / 4 // APB1 Frequency
	}
	return clock / baudRate
}

//---------- SPI related types and code

// SPI on the STM32Fxxx using MODER / alternate function pins
type SPI struct {
	Bus             *stm32.SPI_Type
	AltFuncSelector stm32.AltFunc
}

// Set baud rate for SPI
func (spi SPI) getBaudRate(config SPIConfig) uint32 {
	var conf uint32

	localFrequency := config.Frequency
	if spi.Bus != stm32.SPI1 {
		// Assume it's SPI2 or SPI3 on APB1 at 1/2 the clock frequency of APB2, so
		//  we want to pretend to request 2x the baudrate asked for
		localFrequency = localFrequency * 2
	}

	// set frequency dependent on PCLK prescaler. Since these are rather weird
	// speeds due to the CPU freqency, pick a range up to that frquency for
	// clients to use more human-understandable numbers, e.g. nearest 100KHz

	// These are based on APB2 clock frquency (84MHz on the discovery board)
	// TODO: also include the MCU/APB clock setting in the equation
	switch true {
	case localFrequency < 328125:
		conf = stm32.SPI_PCLK_256
	case localFrequency < 656250:
		conf = stm32.SPI_PCLK_128
	case localFrequency < 1312500:
		conf = stm32.SPI_PCLK_64
	case localFrequency < 2625000:
		conf = stm32.SPI_PCLK_32
	case localFrequency < 5250000:
		conf = stm32.SPI_PCLK_16
	case localFrequency < 10500000:
		conf = stm32.SPI_PCLK_8
		// NOTE: many SPI components won't operate reliably (or at all) above 10MHz
		// Check the datasheet of the part
	case localFrequency < 21000000:
		conf = stm32.SPI_PCLK_4
	case localFrequency < 42000000:
		conf = stm32.SPI_PCLK_2
	default:
		// None of the specific baudrates were selected; choose the lowest speed
		conf = stm32.SPI_PCLK_256
	}

	return conf << stm32.SPI_CR1_BR_Pos
}

// Configure SPI pins for input output and clock
func (spi SPI) configurePins(config SPIConfig) {
	config.SCK.ConfigureAltFunc(PinConfig{Mode: PinModeSPICLK}, spi.AltFuncSelector)
	config.SDO.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDO}, spi.AltFuncSelector)
	config.SDI.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDI}, spi.AltFuncSelector)
}