/*
 * Copyright (c) 2015 Travis Geiselbrecht
 *
 * Use of this source code is governed by a MIT-style
 * license that can be found in the LICENSE file or at
 * https://opensource.org/licenses/MIT
 */
#include <lk/reg.h>
#include <lk/trace.h>
#include <lib/cbuf.h>
#include <lk/init.h>
#include <kernel/thread.h>
#include <platform.h>
#include <platform/interrupts.h>
#include <sys/types.h>
#include <target/microblaze-config.h>

#include "uartlite.h"

#define LOCAL_TRACE 0

#define R_RX            0
#define R_TX            1
#define R_STATUS        2
#define R_CTRL          3
#define R_MAX           4

#define STATUS_RXVALID    0x01
#define STATUS_RXFULL     0x02
#define STATUS_TXEMPTY    0x04
#define STATUS_TXFULL     0x08
#define STATUS_IE         0x10
#define STATUS_OVERRUN    0x20
#define STATUS_FRAME      0x40
#define STATUS_PARITY     0x80

#define CONTROL_RST_TX    0x01
#define CONTROL_RST_RX    0x02
#define CONTROL_IE        0x10

#define UART_REG(reg) (*REG32(UARTLITE_BASEADDR + (reg) * 4))

#define RXBUF_SIZE 128
static cbuf_t uart_rx_buf;

void uartlite_putc(char c) {
    while (UART_REG(R_STATUS) & STATUS_TXFULL)
        ;
    UART_REG(R_TX) = c;
}

int uartlite_getc(bool wait) {
#if 0
    char c;
    if (cbuf_read_char(&uart_rx_buf, &c, wait) == 1)
        return c;
#else
    do {
        if (UART_REG(R_STATUS) & STATUS_RXVALID) {
            char c = UART_REG(R_RX);
            return c;
        }
    } while (wait);
#endif

    return -1;
}

static enum handler_return uartlite_irq(void *arg) {
    bool resched = false;

    /* while receive fifo not empty, read a char */
    while (UART_REG(R_STATUS) & STATUS_RXVALID) {
        char c = UART_REG(R_RX);
        cbuf_write_char(&uart_rx_buf, c, false);

        resched = true;
    }

    return resched ? INT_RESCHEDULE : INT_NO_RESCHEDULE;
}

static void uartlite_init(uint level) {
    TRACE;

    //UART_REG(R_CTRL) = CONTROL_RST_TX | CONTROL_RST_RX;
//    UART_REG(R_CTRL) |= CONTROL_IE;

    cbuf_initialize(&uart_rx_buf, RXBUF_SIZE);

//    register_int_handler(UARTLITE_IRQ, uartlite_irq, NULL);
//    unmask_interrupt(UARTLITE_IRQ);
}

LK_INIT_HOOK(uartlite, uartlite_init, LK_INIT_LEVEL_PLATFORM);