serial_sicc.c

底层驱动开发

               clockSource = 324000000;
           }
           else {
               clockSource = 216000000;
           }
           clockSource = clockSource/(unsigned long)((temp&0x00FC0000)>>18);
           divisor = clockSource/(16*baud) - 1;
           /* divisor has only 12 bits of resolution */
           if(divisor>0x00000FFF){
               divisor=0x00000FFF;
           }

           quot = divisor;
        }

        if (baud == 38400 &&
            ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST))
            quot = info->state->custom_divisor;

        if (!quot && old_termios) {
            info->tty->termios->c_cflag &= ~CBAUD;
            info->tty->termios->c_cflag |= (old_termios->c_cflag & CBAUD);
            old_termios = NULL;
        }
    } while (quot == 0 && old_termios);

    /* As a last resort, if the quotient is zero, default to 9600 bps */
    if (!quot)
        quot = (info->port->uartclk / (16 * 9600)) - 1;

    info->timeout = info->port->fifosize * HZ * bits / baud;
    info->timeout += HZ/50;     /* Add .02 seconds of slop */

    if (cflag & CRTSCTS)
        info->flags |= ASYNC_CTS_FLOW;
    else
        info->flags &= ~ASYNC_CTS_FLOW;
    if (cflag & CLOCAL)
        info->flags &= ~ASYNC_CHECK_CD;
    else
        info->flags |= ASYNC_CHECK_CD;

    /*
     * Set up parity check flag
     */
#define RELEVENT_IFLAG(iflag)   ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

    info->read_status_mask = _LSR_OE_MASK;
    if (I_INPCK(info->tty))
        info->read_status_mask |= _LSR_FE_MASK | _LSR_PE_MASK;
    if (I_BRKINT(info->tty) || I_PARMRK(info->tty))
        info->read_status_mask |= _LSR_LB_MASK;

    /*
     * Characters to ignore
     */
    info->ignore_status_mask = 0;
    if (I_IGNPAR(info->tty))
        info->ignore_status_mask |= _LSR_FE_MASK | _LSR_PE_MASK;
    if (I_IGNBRK(info->tty)) {
        info->ignore_status_mask |=  _LSR_LB_MASK;
        /*
         * If we're ignoring parity and break indicators,
         * ignore overruns to (for real raw support).
         */
        if (I_IGNPAR(info->tty))
            info->ignore_status_mask |=  _LSR_OE_MASK;
    }

    /* disable interrupts while reading and clearing registers */
    spin_lock_irqsave(&info->state->sicc_lock,flags);

    old_rcr = readb(info->port->uart_base + BL_SICC_RCR);
    old_tcr = readb(info->port->uart_base + BL_SICC_TxCR);


    writeb(0, info->port->uart_base + BL_SICC_RCR);
    writeb(0, info->port->uart_base + BL_SICC_TxCR);

    /*RLBtrace (&ppc403Chan0, 0x2000000c, 0, 0);*/


    spin_unlock_irqrestore(&info->state->sicc_lock,flags);


    /* Set baud rate */
    writeb((quot & 0x00000F00)>>8, info->port->uart_base + BL_SICC_BRDH );
    writeb( quot & 0x00000FF,      info->port->uart_base + BL_SICC_BRDL );

    /* Set CTL2 reg to use external clock (ExtClk) and enable FIFOs. */
    /* For now, do NOT use FIFOs since 403 UART did not have this    */
    /* capability and this driver was inherited from 403UART.        */
    writeb(_CTL2_EXTERN, info->port->uart_base + BL_SICC_CTL2);

    writeb(lcr_h, info->port->uart_base + BL_SICC_LCR);

    writeb(old_rcr, info->port->uart_base + BL_SICC_RCR);  // restore rcr
    writeb(old_tcr, info->port->uart_base + BL_SICC_TxCR); // restore txcr

}


static void siccuart_put_char(struct tty_struct *tty, u_char ch)
{
    struct SICC_info *info = tty->driver_data;
    unsigned long flags;

    if (!tty || !info->xmit.buf)
        return;

    /* lock info->xmit while adding character to tx buffer */
    spin_lock_irqsave(&info->state->sicc_lock,flags);
    if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SICC_XMIT_SIZE) != 0) {
        info->xmit.buf[info->xmit.head] = ch;
        info->xmit.head = (info->xmit.head + 1) & (SICC_XMIT_SIZE - 1);
    }
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
}

static void siccuart_flush_chars(struct tty_struct *tty)
{
    struct SICC_info *info = tty->driver_data;
    unsigned long flags;

    if (info->xmit.head == info->xmit.tail
        || tty->stopped
        || tty->hw_stopped
        || !info->xmit.buf)
        return;

    /* disable interrupts while transmitting characters */
    spin_lock_irqsave(&info->state->sicc_lock,flags);
    siccuart_enable_tx_interrupt(info);
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
}

static int siccuart_write(struct tty_struct *tty,
              const u_char * buf, int count)
{
    struct SICC_info *info = tty->driver_data;
    unsigned long flags;
    int c, ret = 0;

    if (!tty || !info->xmit.buf || !tmp_buf)
        return 0;

    /* lock info->xmit while removing characters from buffer */
    spin_lock_irqsave(&info->state->sicc_lock,flags);
    while (1) {
        c = CIRC_SPACE_TO_END(info->xmit.head,
                      info->xmit.tail,
                      SICC_XMIT_SIZE);
        if (count < c)
            c = count;
        if (c <= 0)
            break;
        memcpy(info->xmit.buf + info->xmit.head, buf, c);
        info->xmit.head = (info->xmit.head + c) &
                  (SICC_XMIT_SIZE - 1);
        buf += c;
        count -= c;
        ret += c;
    }
    if (info->xmit.head != info->xmit.tail
        && !tty->stopped
        && !tty->hw_stopped)
        siccuart_enable_tx_interrupt(info);
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    return ret;
}

static int siccuart_write_room(struct tty_struct *tty)
{
    struct SICC_info *info = tty->driver_data;

    return CIRC_SPACE(info->xmit.head, info->xmit.tail, SICC_XMIT_SIZE);
}

static int siccuart_chars_in_buffer(struct tty_struct *tty)
{
    struct SICC_info *info = tty->driver_data;

    return CIRC_CNT(info->xmit.head, info->xmit.tail, SICC_XMIT_SIZE);
}

static void siccuart_flush_buffer(struct tty_struct *tty)
{
    struct SICC_info *info = tty->driver_data;
    unsigned long flags;

    pr_debug("siccuart_flush_buffer(%d) called\n", tty->index);
    /* lock info->xmit while zeroing buffer counts */
    spin_lock_irqsave(&info->state->sicc_lock,flags);
    info->xmit.head = info->xmit.tail = 0;
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    wake_up_interruptible(&tty->write_wait);
    if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
        tty->ldisc.write_wakeup)
        (tty->ldisc.write_wakeup)(tty);
}

/*
 * This function is used to send a high-priority XON/XOFF character to
 * the device
 */
static void siccuart_send_xchar(struct tty_struct *tty, char ch)
{
    struct SICC_info *info = tty->driver_data;

    info->x_char = ch;
    if (ch)
       siccuart_enable_tx_interrupt(info);
}

static void siccuart_throttle(struct tty_struct *tty)
{
    struct SICC_info *info = tty->driver_data;
    unsigned long flags;

    if (I_IXOFF(tty))
        siccuart_send_xchar(tty, STOP_CHAR(tty));

    if (tty->termios->c_cflag & CRTSCTS) {
        /* disable interrupts while setting modem control lines */
        spin_lock_irqsave(&info->state->sicc_lock,flags);
        info->mctrl &= ~TIOCM_RTS;
        info->port->set_mctrl(info->port, info->mctrl);
        spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    }
}

static void siccuart_unthrottle(struct tty_struct *tty)
{
    struct SICC_info *info = (struct SICC_info *) tty->driver_data;
    unsigned long flags;

    if (I_IXOFF(tty)) {
        if (info->x_char)
            info->x_char = 0;
        else
            siccuart_send_xchar(tty, START_CHAR(tty));
    }

    if (tty->termios->c_cflag & CRTSCTS) {
        /* disable interrupts while setting modem control lines */
        spin_lock_irqsave(&info->state->sicc_lock,flags);
        info->mctrl |= TIOCM_RTS;
        info->port->set_mctrl(info->port, info->mctrl);
        spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    }
}

static int get_serial_info(struct SICC_info *info, struct serial_struct *retinfo)
{
    struct SICC_state *state = info->state;
    struct SICC_port *port = info->port;
    struct serial_struct tmp;

    memset(&tmp, 0, sizeof(tmp));
    tmp.type       = 0;
    tmp.line       = state->line;
    tmp.port       = port->uart_base;
    if (HIGH_BITS_OFFSET)
        tmp.port_high = port->uart_base >> HIGH_BITS_OFFSET;
    tmp.irq        = port->irqrx;
    tmp.flags      = 0;
    tmp.xmit_fifo_size = port->fifosize;
    tmp.baud_base      = port->uartclk / 16;
    tmp.close_delay    = state->close_delay;
    tmp.closing_wait   = state->closing_wait;
    tmp.custom_divisor = state->custom_divisor;

    if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
        return -EFAULT;
    return 0;
}

static int set_serial_info(struct SICC_info *info,
               struct serial_struct *newinfo)
{
    struct serial_struct new_serial;
    struct SICC_state *state, old_state;
    struct SICC_port *port;
    unsigned long new_port;
    unsigned int i, change_irq, change_port;
    int retval = 0;

    if (copy_from_user(&new_serial, newinfo, sizeof(new_serial)))
        return -EFAULT;

    state = info->state;
    old_state = *state;
    port = info->port;

    new_port = new_serial.port;
    if (HIGH_BITS_OFFSET)
        new_port += (unsigned long) new_serial.port_high << HIGH_BITS_OFFSET;

    change_irq  = new_serial.irq != port->irqrx;
    change_port = new_port != port->uart_base;

    if (!capable(CAP_SYS_ADMIN)) {
        if (change_irq || change_port ||
            (new_serial.baud_base != port->uartclk / 16) ||
            (new_serial.close_delay != state->close_delay) ||
            (new_serial.xmit_fifo_size != port->fifosize) ||
            ((new_serial.flags & ~ASYNC_USR_MASK) !=
             (state->flags & ~ASYNC_USR_MASK)))
            return -EPERM;
        state->flags = ((state->flags & ~ASYNC_USR_MASK) |
                (new_serial.flags & ASYNC_USR_MASK));
        info->flags = ((info->flags & ~ASYNC_USR_MASK) |
                   (new_serial.flags & ASYNC_USR_MASK));
        state->custom_divisor = new_serial.custom_divisor;
        goto check_and_exit;
    }

    if ((new_serial.irq >= NR_IRQS) || (new_serial.irq < 0) ||
        (new_serial.baud_base < 9600))
        return -EINVAL;

    if (new_serial.type && change_port) {
        for (i = 0; i < SERIAL_SICC_NR; i++)
            if ((port != sicc_ports + i) &&
                sicc_ports[i].uart_base != new_port)
                return -EADDRINUSE;
    }

    if ((change_port || change_irq) && (state->count > 1))
        return -EBUSY;

    /*
     * OK, past this point, all the error checking has been done.
     * At this point, we start making changes.....
     */
    port->uartclk = new_serial.baud_base * 16;
    state->flags = ((state->flags & ~ASYNC_FLAGS) |
            (new_serial.flags & ASYNC_FLAGS));
    info->flags = ((state->flags & ~ASYNC_INTERNAL_FLAGS) |
               (info->flags & ASYNC_INTERNAL_FLAGS));
    state->custom_divisor = new_serial.custom_divisor;
    state->close_delay = new_serial.close_delay * HZ / 100;
    state->closing_wait = new_serial.closing_wait * HZ / 100;
    info->tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
    port->fifosize = new_serial.xmit_fifo_size;

    if (change_port || change_irq) {
        /*
         * We need to shutdown the serial port at the old
         * port/irq combination.
         */
        siccuart_shutdown(info);
        port->irqrx = new_serial.irq;
        port->uart_base = new_port;
    }

check_and_exit:
    if (!port->uart_base)
        return 0;
    if (info->flags & ASYNC_INITIALIZED) {
        if ((old_state.flags & ASYNC_SPD_MASK) !=
            (state->flags & ASYNC_SPD_MASK) ||
            (old_state.custom_divisor != state->custom_divisor)) {
            if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
                info->tty->alt_speed = 57600;
            if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
                info->tty->alt_speed = 115200;
            if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
                info->tty->alt_speed = 230400;
            if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
                info->tty->alt_speed = 460800;
            siccuart_change_speed(info, NULL);
        }
    } else
        retval = siccuart_startup(info);
    return retval;
}


/*
 * get_lsr_info - get line status register info
 */
static int get_lsr_info(struct SICC_info *info, unsigned int *value)
{
    unsigned int result, status;
    unsigned long flags;

    /* disable interrupts while reading status from port */
    spin_lock_irqsave(&info->state->sicc_lock,flags);
    status = readb(info->port->uart_base +  BL_SICC_LSR);
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    result = status & _LSR_TSR_EMPTY ? TIOCSER_TEMT : 0;

    /*
     * If we're about to load something into the transmit
     * register, we'll pretend the transmitter isn't empty to
     * avoid a race condition (depending on when the transmit
     * interrupt happens).
     */
    if (info->x_char ||
        ((CIRC_CNT(info->xmit.head, info->xmit.tail,
               SICC_XMIT_SIZE) > 0) &&
         !info->tty->stopped && !info->tty->hw_stopped))