File content as of revision 20:4263a77256ae:

/* mbed Microcontroller Library
 * Copyright (c) 2006-2013 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 "serial_api.h"

// math.h required for floating point operations for baud rate calculation
#include <math.h>

#include <string.h>

#include "cmsis.h"
#include "pinmap.h"
#include "error.h"

#define UART_CLOCK_HZ 47972352u
#define UART_NUM    1

static const PinMap PinMap_UART_TX[] = {
    {PTB1, UART_0, 2},
    {NC  , NC    , 0}
};

static const PinMap PinMap_UART_RX[] = {
    {PTB2, UART_0, 2},
    {NC  , NC    , 0}
};

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);
    if ((int)uart == NC) {
        error("Serial pinout mapping failed");
    }

    obj->uart = (UARTLP_Type *)uart;
    // enable clk
    switch (uart) {
        case UART_0:
            SIM->SOPT2 |= 1 << SIM_SOPT2_UART0SRC_SHIFT;
            SIM->SCGC5 |= SIM_SCGC5_PORTB_MASK;
            SIM->SCGC4 |= SIM_SCGC4_UART0_MASK;
            break;
    }
    // Disable UART before changing registers
    obj->uart->C2 &= ~(UART0_C2_RE_MASK | UART0_C2_TE_MASK);

    switch (uart) {
        case UART_0:
            obj->index = 0;
            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
    pin_mode(tx, PullUp);
    pin_mode(rx, PullUp);

    obj->uart->C2 |= (UART0_C2_RE_MASK | UART0_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 & (UART0_C2_RE_MASK | UART0_C2_TE_MASK));

    // Disable UART before changing registers
    obj->uart->C2 &= ~(UART0_C2_RE_MASK | UART0_C2_TE_MASK);

    // First we check to see if the basic divide with no DivAddVal/MulVal
    // ratio gives us an integer result. If it does, we set DivAddVal = 0,
    // MulVal = 1. Otherwise, we search the valid ratio value range to find
    // the closest match. This could be more elegant, using search methods
    // and/or lookup tables, but the brute force method is not that much
    // slower, and is more maintainable.
    uint16_t DL = UART_CLOCK_HZ / (16 * baudrate);

    // set BDH and BDL
    obj->uart->BDH = (obj->uart->BDH & ~(0x1f)) | ((DL >> 8) & 0x1f);
    obj->uart->BDL = (obj->uart->BDL & ~(0xff)) | ((DL >> 0) & 0xff);

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

void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
    uint8_t m10 = 0;

    // save C2 state
    uint8_t c2_state = (obj->uart->C2 & (UART0_C2_RE_MASK | UART0_C2_TE_MASK));

    // Disable UART before changing registers
    obj->uart->C2 &= ~(UART0_C2_RE_MASK | UART0_C2_TE_MASK);

    // 8 data bits = 0 ... 9 data bits = 1
    if ((data_bits < 8) || (data_bits > 9)) {
        error("Invalid number of bits (%d) in serial format, should be 8..9\r\n", data_bits);
    }
    data_bits -= 8;

    uint8_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:
            error("Invalid serial parity setting\r\n");
            return;
    }

    // 1 stop bits = 0, 2 stop bits = 1
    if ((stop_bits != 1) && (stop_bits != 2)) {
        error("Invalid stop bits specified\r\n");
    }
    stop_bits -= 1;

    // 9 data bits + parity
    if (data_bits == 2) {
        // only uart0 supports 10 bit communication
        if (obj->index != 0) {
            error("Invalid number of bits (9) to be used with parity\r\n");
        }
        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 &= ~UARTLP_C4_M10_MASK;
        obj->uart->C4 |= (m10 << UARTLP_C4_M10_SHIFT);
    }

    // stop bits
    obj->uart->BDH &= ~UART0_BDH_SBNS_MASK;
    obj->uart->BDH |= (stop_bits << UART0_BDH_SBNS_SHIFT);

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

static inline void uart_irq(uint8_t status, uint32_t index) {
    if (serial_irq_ids[index] != 0) {
        if (status & UART0_S1_TDRE_MASK)
            irq_handler(serial_irq_ids[index], TxIrq);

        if (status & UART0_S1_RDRF_MASK)
            irq_handler(serial_irq_ids[index], RxIrq);
    }
}

void uart0_irq() {
    uart_irq(UART0->S1, 0);
    if (UART0->S1 & UART0_S1_OR_MASK)
        UART0->S1 |= UART0_S1_OR_MASK;
}

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_IRQn;
            vector = (uint32_t)&uart0_irq;
            break;
    }

    if (enable) {
        switch (irq) {
            case RxIrq:
                obj->uart->C2 |= (UART0_C2_RIE_MASK);
                break;
            case TxIrq:
                obj->uart->C2 |= (UART0_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 &= ~(UART0_C2_RIE_MASK);
                break;
            case TxIrq:
                obj->uart->C2 &= ~(UART0_C2_TIE_MASK);
                break;
        }
        switch (other_irq) {
            case RxIrq:
                all_disabled = (obj->uart->C2 & (UART0_C2_RIE_MASK)) == 0;
                break;
            case TxIrq:
                all_disabled = (obj->uart->C2 & (UART0_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) {
    // check overrun
    if (obj->uart->S1 &  UART0_S1_OR_MASK) {
        obj->uart->S1 |= UART0_S1_OR_MASK;
    }
    return (obj->uart->S1 & UART0_S1_RDRF_MASK);
}

int serial_writable(serial_t *obj) {
    // check overrun
    if (obj->uart->S1 &  UART0_S1_OR_MASK) {
        obj->uart->S1 |= UART0_S1_OR_MASK;
    }
    return (obj->uart->S1 & UART0_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 |= UART0_C2_SBK_MASK; 
}

void serial_break_clear(serial_t *obj) {
    obj->uart->C2 &= ~UART0_C2_SBK_MASK;
}