synth/arm/uart.cc

#include "uart.h"

#include "gpio.h"
#include "ring_buffer.h"
#include "trace.h"

namespace {

constexpr uintptr_t kUart0BaseAddress = 0x40001000;
XUartLite uart0_inst;
XUartLite_Config uart0_config = {
    .DeviceId = 0,
    .RegBaseAddr = kUart0BaseAddress,
    .BaudRate = 115200,
    .UseParity = false,
    .DataBits = 8,
};

constexpr size_t kUartTxBufferSize = 256;
std::array<std::byte, kUartTxBufferSize> tx_buffer = {};
RingBuffer tx_ring_buffer{.buffer = tx_buffer};

}  // namespace

XUartLite* uart0 = &uart0_inst;

void InitUarts() {
    XUartLite_CfgInitialize(uart0, &uart0_config, uart0_config.RegBaseAddr);
}

extern "C" uint8_t XUartLite_GetSR(XUartLite* InstancePtr);
#define XUL_SR_TX_FIFO_EMPTY 0x04 /* transmit FIFO empty */

void UartSendCrash(std::span<const std::byte> data) {
    while (data.size() > 0) {
        while ((XUartLite_GetSR(uart0) & XUL_SR_TX_FIFO_EMPTY) == 0) {
        }
        auto* dat =
            reinterpret_cast<uint8_t*>(const_cast<std::byte*>(data.data()));
        uint8_t sent = XUartLite_Send(uart0, dat, data.size());
        data = data.subspan(sent);
    }
    while ((XUartLite_GetSR(uart0) & XUL_SR_TX_FIFO_EMPTY) == 0) {
    }
}

// blocking
void UartSend(std::span<const std::byte> data) {
    while (!tx_ring_buffer.Store(data)) {
    }

    if (!XUartLite_IsSending(uart0)) {
        XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(),
                       tx_ring_buffer.ContiguousAvailableData());
    }
}

void HandleUartTxFromIsr(void*, unsigned int transmitted) {
    tracing::trace(tracing::TraceEvent::kUartTxCb);
    tx_ring_buffer.Pop(transmitted);
    if (tx_ring_buffer.AvailableData() > 0) {
        XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(),
                       tx_ring_buffer.ContiguousAvailableData());
    }
}