/* Copyright 2018 Canaan Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdint.h>
#include <stdio.h>
#include "encoding.h"
#include "sysctl.h"
#include "uarths.h"

volatile uarths_t *const uarths = (volatile uarths_t *)UARTHS_BASE_ADDR;

typedef struct _uarths_instance
{
    plic_irq_callback_t callback;
    void *ctx;
    uarths_interrupt_mode_t uarths_interrupt_mode;
} uarths_instance_t;

uarths_instance_t g_uarths_instance;

uarths_interrupt_mode_t uarths_get_interrupt_mode(void)
{
    uint32_t v_rx_interrupt = uarths->ip.rxwm;
    uint32_t v_tx_interrupt = uarths->ip.txwm;
    return (v_rx_interrupt << 1) | v_tx_interrupt;
}

int uarths_irq_callback(void *ctx)
{
    uarths_instance_t *uart_context = (uarths_instance_t *)ctx;

    if(uart_context->callback)
        uart_context->callback(uart_context->ctx);
    return 0;
}

void uarths_set_interrupt_cnt(uarths_interrupt_mode_t interrupt_mode, uint8_t cnt)
{
    switch(interrupt_mode)
    {
        case UARTHS_SEND:
            uarths->txctrl.txcnt = cnt;
            break;
        case UARTHS_RECEIVE:
            uarths->rxctrl.rxcnt = cnt;
            break;
        case UARTHS_SEND_RECEIVE:
        default:
            uarths->txctrl.txcnt = cnt;
            uarths->rxctrl.rxcnt = cnt;
            break;
    }
}

void uarths_set_irq(uarths_interrupt_mode_t interrupt_mode, plic_irq_callback_t uarths_callback, void *ctx, uint32_t priority)
{
    g_uarths_instance.callback = uarths_callback;
    g_uarths_instance.ctx = ctx;

    switch(interrupt_mode)
    {
        case UARTHS_SEND:
            uarths->ie.txwm = 1;
            uarths->ie.rxwm = 0;
            break;
        case UARTHS_RECEIVE:
            uarths->ie.txwm = 0;
            uarths->ie.rxwm = 1;
            break;
        default:
            uarths->ie.txwm = 1;
            uarths->ie.rxwm = 1;
            break;
    }
    g_uarths_instance.uarths_interrupt_mode = interrupt_mode;

    plic_set_priority(IRQN_UARTHS_INTERRUPT, priority);
    plic_irq_register(IRQN_UARTHS_INTERRUPT, uarths_irq_callback, &g_uarths_instance);
    plic_irq_enable(IRQN_UARTHS_INTERRUPT);
}

int uarths_putchar(char c)
{
    while(uarths->txdata.full)
        continue;
    uarths->txdata.data = (uint8_t)c;

    return (c & 0xff);
}

int uarths_getchar(void)
{
    /* while not empty */
    uarths_rxdata_t recv = uarths->rxdata;

    if(recv.empty)
        return EOF;
    else
        return (recv.data & 0xff);
}

/* [Deprecated] this function will remove in future */
int uarths_getc(void) __attribute__((weak, alias("uarths_getchar")));

size_t uarths_receive_data(uint8_t *buf, size_t buf_len)
{
    size_t i;
    for(i = 0; i < buf_len; i++)
    {
        uarths_rxdata_t recv = uarths->rxdata;
        if(recv.empty)
            break;
        else
            buf[i] = (recv.data & 0xFF);
    }
    return i;
}

size_t uarths_send_data(const uint8_t *buf, size_t buf_len)
{
    size_t write = 0;
    while(write < buf_len)
    {
        uarths_putchar(*buf++);
        write++;
    }
    return write;
}

int uarths_puts(const char *s)
{
    while(*s)
        if(uarths_putchar(*s++) != 0)
            return -1;
    return 0;
}

void uarths_init(void)
{
    uint32_t freq = sysctl_clock_get_freq(SYSCTL_CLOCK_CPU);
    uint16_t div = freq / 115200 - 1;

    /* Set UART registers */
    uarths->div.div = div;
    uarths->txctrl.txen = 1;
    uarths->rxctrl.rxen = 1;
    uarths->txctrl.txcnt = 0;
    uarths->rxctrl.rxcnt = 0;
    uarths->ip.txwm = 1;
    uarths->ip.rxwm = 1;
    uarths->ie.txwm = 0;
    uarths->ie.rxwm = 1;
}

void uarths_config(uint32_t baud_rate, uarths_stopbit_t stopbit)
{
    uint32_t freq = sysctl_clock_get_freq(SYSCTL_CLOCK_CPU);
    uint16_t div = freq / baud_rate - 1;
    uarths->div.div = div;
    uarths->txctrl.nstop = stopbit;
}