Subversion Repositories igor

#include <avr/io.h>

#include <avr/interrupt.h>

#include <global.h>

#include <stdint.h>

#include <device.h>

#include <dispatch.h>

#include <stdlib.h>

#include <string.h>

#define BAUD 9600

#define MUBRR ((FOSC/16/BAUD)-1)

static struct {

        struct buf readbuf;

        struct buf writebuf;

} usart_data;

#define XON     0x11

#define XOFF    0x13

/* Internal flow control. */

uint8_t xflow_local;

/* Internal flow control for transmit. */

uint8_t xflow_state_transmit;

/* External flow control. */

uint8_t xflow_remote;

static int8_t usart_send_data(void);

static igordev_read_fn_t usart_recv;

static igordev_write_fn_t usart_send;

static igordev_init_fn_t init;

static igordev_flush_fn_t usart_flush;

/* XXX: Not completed. */

struct igordev igordev_usart = {

        .init = init,

        .read = usart_recv,

        .write = usart_send,

        .flush = usart_flush,

        .read_status = 0,

        .write_status = 0,

        .priv = &usart_data

};

void init() {

        /* Set internal stuff first. */

        const char *uhello = "Hello, world from USART!\r\n";

        buf_init(&usart_data.readbuf);

        buf_init(&usart_data.writebuf);

        igordev_usart.read_status = igordev_usart.write_status = IDEV_STATUS_OK;

        xflow_local = xflow_remote = xflow_state_transmit = XON;

        igordev_usart.id = (CAN_READ | CAN_WRITE |

            (DEVTYPE_SERIAL << DEVTYPE_OFFSET));

        // Disable powersaving

        PRR0 &= ~(1<<PRUSART0);

        // Set tranfser speed

        UBRR0L = (uint8_t)MUBRR;

        UBRR0H = (uint8_t)(MUBRR>>8);

        // Enable reciever, transmitter and interrupts ( Not active until global interrupts are enabled)

        UCSR0B = (1<<RXEN0)|(1<<TXEN0)|(1<<RXCIE0);

        // Set format, stopbits, mode: 8n1

        UCSR0C = (0<<USBS0)|(0<<UPM01)|(0<<UPM00)|(0<<UMSEL01)|(0<<UMSEL00)|(3<<UCSZ00);

        buf_write(&usart_data.writebuf, (uint8_t *)uhello, strlen(uhello));

        // XXX: Return value not checked

        dispatch_request_make(&igordev_usart, REQ_TYPE_FLUSH, 0, 0, NULL);

}

// Received a word

ISR(SIG_USART0_RECV) {

        // Read UDR to reset interrupt flag

        struct buf *buf;

        uint8_t data;

        igordev_usart.read_status = IDEV_STATUS_INTR;

        /* Store in the buffers. */

        data = UDR0;

        /* If we received external flow control signal. */

        if (data == XOFF || data == XON) {

                xflow_remote = data;

                igordev_usart.read_status = IDEV_STATUS_OK;

                return;

        }

        buf = &usart_data.readbuf;

#define ONESQUARE (MAXBUFLEN / 4)

        if (buf_writesleft(buf) < (ONESQUARE - 1))

                xflow_local = XOFF;

        buf_write(buf, &data, 1);

        igordev_usart.read_status = IDEV_STATUS_OK;

#if 0

        // Check if we have a second byte buffered.

        if ( !(UCSR0A & ( 1>> RXC0 ) ) ) {

            igordev_usart.read_status = IDEV_STATUS_INTR;

            /* Store in the buffers. */

            data = UDR0;

            /* If we received external flow control signal. */

            if (data == XOFF || data == XON) {

                xflow_remote = data;

                igordev_usart.read_status = IDEV_STATUS_OK;

                return;

            }

            if (buf_writesleft(buf) < (ONESQUARE - 1))

                xflow_local = XOFF;

            buf_write(buf, &data, 1);

            igordev_usart.read_status = IDEV_STATUS_OK;

        }

#endif

}

/*

 * Read num bytes from addr and place it into data.

 * Data assumed to be a buffer large enough for num bytes.

 * Addr here is ignored, since serial is a streaming device.

 */

uint8_t

usart_recv(uint64_t addr, uint8_t *data, uint8_t num)

{

        struct buf *buf;

        uint8_t byte;

        uint8_t i;

        buf = &usart_data.readbuf;

        /* Avoid making larger buffers for now. */

        for (i = 0; i < num; i++) {

                buf_read(buf, &byte, 1);

                if (BUF_EMPTY(buf))

                        break;

                *(data + i) = byte;

        }

        return (i);

}

/*

 * Example of transmit. Currently initiates the write and let the TX interrupt

 * handle the rest.

 */

uint8_t

usart_send(uint64_t addr, uint8_t *data, uint8_t num)

{

        struct buf *buf;

        uint8_t i = 0;

        /* Transmit only once, and the buffer will be flushed anyway. */

        /* Only output data if we're provided with data. */

        if (num > 0 && data != NULL) {

                /* Copy data into write buffer. */

                buf = &usart_data.writebuf;

                i = buf_write(buf, data, num);

        }

        return (i);

}

/* Send whatever we have in the output buffer. */

static void

usart_flush(void)

{

        struct buf *buf;

        buf = &usart_data.writebuf;

        igordev_usart.write_status = IDEV_STATUS_BUSY;

        /* Flush as long as it is ok. */

        while (!BUF_EMPTY(buf) && usart_send_data() == 0);

        igordev_usart.write_status = IDEV_STATUS_OK;

}

/* Sends the next byte in the buffer. */

static int8_t

usart_send_data(void)

{

        struct buf *buf;

        uint8_t data;

        /* Cannot send data yet. */

        if (xflow_remote == XOFF)

                return (-1);

        buf = &usart_data.writebuf;

        switch (xflow_local) {

        case XON:

                /* If we have few reads left, make sure we can get more. */

                buf_read(buf, &data, 1);

                if (BUF_EMPTY(buf))

                        return (-1);

                break;

        case XOFF:

                /* If we have not signalled OK again, do it. */

                if (buf_readsleft(buf) >= (MAXBUFLEN - ONESQUARE) &&

                    xflow_state_transmit == XOFF) {

                        data = XON;

                        xflow_state_transmit = XON;

                        xflow_local = XON;

                        break;

                }

                /* If we have not sent the xflow_state signal, do it. */

                if (xflow_state_transmit == XON) {

                        data = XOFF;

                        xflow_state_transmit = XOFF;

                        break;

                }

                return (-1);

        default:

                return (-1);

        }

        while (!(UCSR0A & (1<<UDRE0)));

        UDR0 = data; /* Initiate transfer. */

        return (0);

}

#if 0

void

usart_loopback(void *arg)

{

        struct buf *in;

        uint8_t data[MAXBUFLEN];

        uint8_t i, num;

        cli();

        in = &usart_data.readbuf;

        /* Fill output buffer from input buffer. */

        i = 0;

        num = buf_read(in, data, MAXBUFLEN);

        usart_send(data, num);

        sei();

}

#endif