// See LICENSE for license details.

#include "femto.h"

enum {
    /* UART Registers */
    UART_REG_TXFIFO = 0,
    UART_REG_RXFIFO = 1,
    UART_REG_TXCTRL = 2,
    UART_REG_RXCTRL = 3,
    UART_REG_IE     = 4,
    UART_REG_IP     = 5,
    UART_REG_DIV    = 6,

    /* TXCTRL register */
    UART_TXEN       = 1,
    UART_TXSTOP     = 2,

    /* RXCTRL register */
    UART_RXEN       = 1,

    /* IP register */
    UART_IP_TXWM    = 1,
    UART_IP_RXWM    = 2
};

static volatile int *uart;

static void sifive_uart_init()
{
	uart = (int *)(void *)getauxval(SIFIVE_UART0_CTRL_ADDR);
	uint32_t uart_freq = getauxval(UART0_CLOCK_FREQ);
	uint32_t baud_rate = getauxval(UART0_BAUD_RATE);
    uint32_t divisor = uart_freq / baud_rate - 1;
    uart[UART_REG_DIV] = divisor;
    uart[UART_REG_TXCTRL] = UART_TXEN;
    uart[UART_REG_RXCTRL] = UART_RXEN;
    uart[UART_REG_IE] = 0;
}

static int sifive_uart_getchar()
{
    int ch = uart[UART_REG_RXFIFO];
    if (ch < 0) return -1;
    return ch;
}

static int sifive_uart_putchar(int ch)
{
    while (uart[UART_REG_TXFIFO] < 0);
    return uart[UART_REG_TXFIFO] = ch & 0xff;
}

console_device_t console_sifive_uart = {
    sifive_uart_init,
    sifive_uart_getchar,
    sifive_uart_putchar
};