/* mbed Microcontroller Library
 * Copyright (c) 2006-2015 ARM Limited
 *
 * 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 "mbed_assert.h"
#include "serial_api.h"

#include <string.h>

#include "cmsis.h"
#include "pinmap.h"
#include "clk_freqs.h"
#include "PeripheralPins.h"

#define UART_NUM    3

static uint32_t serial_irq_ids[UART_NUM] = {0};
static uart_irq_handler irq_handler;

int stdio_uart_inited = 0;
serial_t stdio_uart;

void serial_init(serial_t *obj, PinName tx, PinName rx) {
    // determine the UART to use
    UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
    UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
    UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
    MBED_ASSERT((int)uart != NC);

    obj->uart = (UART_Type *)uart;
    // enable clk
    switch (uart) {
        case UART_0: 
            mcgpllfll_frequency();
            SIM->SCGC4 |= SIM_SCGC4_UART0_MASK; 
            break;
        case UART_1:
            mcgpllfll_frequency();
            SIM->SCGC4 |= SIM_SCGC4_UART1_MASK;
            break;
        case UART_2:
            SIM->SCGC4 |= SIM_SCGC4_UART2_MASK;
            break;
    }
    // Disable UART before changing registers
    obj->uart->C2 &= ~(UART_C2_RE_MASK | UART_C2_TE_MASK);

    switch (uart) {
        case UART_0:
            obj->index = 0;
            break;
        case UART_1:
            obj->index = 1;
            break;
        case UART_2:
            obj->index = 2;
            break;
    }

    // set default baud rate and format
    serial_baud  (obj, 9600);
    serial_format(obj, 8, ParityNone, 1);

    // pinout the chosen uart
    pinmap_pinout(tx, PinMap_UART_TX);
    pinmap_pinout(rx, PinMap_UART_RX);

    // set rx/tx pins in PullUp mode
    if (tx != NC) {
        pin_mode(tx, PullUp);
    }
    if (rx != NC) {
        pin_mode(rx, PullUp);
    }

    obj->uart->C2 |= (UART_C2_RE_MASK | UART_C2_TE_MASK);

    if (uart == STDIO_UART) {
        stdio_uart_inited = 1;
        memcpy(&stdio_uart, obj, sizeof(serial_t));
    }
}

void serial_free(serial_t *obj) {
    serial_irq_ids[obj->index] = 0;
}

void serial_baud(serial_t *obj, int baudrate) {
    // save C2 state
    uint8_t c2_state = (obj->uart->C2 & (UART_C2_RE_MASK | UART_C2_TE_MASK));
    
    // Disable UART before changing registers
    obj->uart->C2 &= ~(UART_C2_RE_MASK | UART_C2_TE_MASK);
    
    uint32_t PCLK;
    if (obj->uart != UART2) {
        PCLK = mcgpllfll_frequency();
    }
    else {
        PCLK = bus_frequency();
    }
    
    uint16_t DL = PCLK / (16 * baudrate);
    uint32_t BRFA = (2 * PCLK) / baudrate - 32 * DL;

    // set BDH and BDL
    obj->uart->BDH = (obj->uart->BDH & ~(0x1f)) | ((DL >> 8) & 0x1f);
    obj->uart->BDL = (obj->uart->BDL & ~(0xff)) | ((DL >> 0) & 0xff);
    
    obj->uart->C4 &= ~0x1F;
    obj->uart->C4 |= BRFA & 0x1F;    
    
    // restore C2 state
    obj->uart->C2 |= c2_state;
}

void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
    MBED_ASSERT((stop_bits == 1) || (stop_bits == 2));
    MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven));
    MBED_ASSERT((data_bits == 8) || (data_bits == 9));

    // save C2 state
    uint32_t c2_state = (obj->uart->C2 & (UART_C2_RE_MASK | UART_C2_TE_MASK));

    // Disable UART before changing registers
    obj->uart->C2 &= ~(UART_C2_RE_MASK | UART_C2_TE_MASK);

    // 8 data bits = 0 ... 9 data bits = 1
    data_bits -= 8;

    uint32_t parity_enable, parity_select;
    switch (parity) {
        case ParityNone:
            parity_enable = 0;
            parity_select = 0;
            break;
        case ParityOdd :
            parity_enable = 1;
            parity_select = 1;
            data_bits++;
            break;
        case ParityEven:
            parity_enable = 1;
            parity_select = 0;
            data_bits++;
            break;
        default:
            break;
    }

    stop_bits -= 1;

    uint32_t m10 = 0;

    // 9 data bits + parity - only uart0 support
    if (data_bits == 2) {
        MBED_ASSERT(obj->index == 0);
        data_bits = 0;
        m10 = 1;
    }

    // data bits, parity and parity mode
    obj->uart->C1 = ((data_bits << 4)
                  |  (parity_enable << 1)
                  |  (parity_select << 0));

    //enable 10bit mode if needed
    if (obj->index == 0) {
        obj->uart->C4 &= ~UART_C4_M10_MASK;
        obj->uart->C4 |= (m10 << UART_C4_M10_SHIFT);
    }

    // stop bits
    obj->uart->BDH &= ~UART_BDH_SBR_MASK;
    obj->uart->BDH |= (stop_bits << UART_BDH_SBR_SHIFT);

    // restore C2 state
    obj->uart->C2 |= c2_state;
}

/******************************************************************************
 * INTERRUPTS HANDLING
 ******************************************************************************/
static inline void uart_irq(uint8_t status, uint32_t index) {
    if (serial_irq_ids[index] != 0) {
        if (status & UART_S1_TDRE_MASK)
            irq_handler(serial_irq_ids[index], TxIrq);

        if (status & UART_S1_RDRF_MASK)
            irq_handler(serial_irq_ids[index], RxIrq);
    }
}

void uart0_irq() {uart_irq(UART0->S1, 0);}
void uart1_irq() {uart_irq(UART1->S1, 1);}
void uart2_irq() {uart_irq(UART2->S1, 2);}

void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
    irq_handler = handler;
    serial_irq_ids[obj->index] = id;
}

void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
    IRQn_Type irq_n = (IRQn_Type)0;
    uint32_t vector = 0;
    switch ((int)obj->uart) {
        case UART_0:
            irq_n=UART0_RX_TX_IRQn;
            vector = (uint32_t)&uart0_irq;
            break;
        case UART_1:
            irq_n=UART1_RX_TX_IRQn;
            vector = (uint32_t)&uart1_irq;
            break;
        case UART_2:
            irq_n=UART2_RX_TX_IRQn;
            vector = (uint32_t)&uart2_irq;
            break;
    }

    if (enable) {
        switch (irq) {
            case RxIrq:
                obj->uart->C2 |= (UART_C2_RIE_MASK);
                break;
            case TxIrq:
                obj->uart->C2 |= (UART_C2_TIE_MASK);
                break;
        }
        NVIC_SetVector(irq_n, vector);
        NVIC_EnableIRQ(irq_n);

    } else { // disable
        int all_disabled = 0;
        SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
        switch (irq) {
            case RxIrq:
                obj->uart->C2 &= ~(UART_C2_RIE_MASK);
                break;
            case TxIrq:
                obj->uart->C2 &= ~(UART_C2_TIE_MASK);
                break;
        }
        switch (other_irq) {
            case RxIrq:
                all_disabled = (obj->uart->C2 & (UART_C2_RIE_MASK)) == 0;
                break;
            case TxIrq:
                all_disabled = (obj->uart->C2 & (UART_C2_TIE_MASK)) == 0;
                break;
        }
        if (all_disabled)
            NVIC_DisableIRQ(irq_n);
    }
}

int serial_getc(serial_t *obj) {
    while (!serial_readable(obj));
    return obj->uart->D;
}

void serial_putc(serial_t *obj, int c) {
    while (!serial_writable(obj));
    obj->uart->D = c;
}

int serial_readable(serial_t *obj) {

    return (obj->uart->S1 & UART_S1_RDRF_MASK);
}

int serial_writable(serial_t *obj) {

    return (obj->uart->S1 & UART_S1_TDRE_MASK);
}

void serial_clear(serial_t *obj) {
}

void serial_pinout_tx(PinName tx) {
    pinmap_pinout(tx, PinMap_UART_TX);
}

void serial_break_set(serial_t *obj) {
    obj->uart->C2 |= UART_C2_SBK_MASK;
}

void serial_break_clear(serial_t *obj) {
    obj->uart->C2 &= ~UART_C2_SBK_MASK;
}