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scoutos / prex-0.9.0 / bsp / drv / dev / serial / ns16550.c @ 03e9c04a

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/*-
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 * Copyright (c) 2009, Kohsuke Ohtani
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the author nor the names of any co-contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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/*
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 * ns16550.c - NS16550 serial driver
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 */
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#include <driver.h>
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#include <tty.h>
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#include <serial.h>
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/* #define DEBUG_NS16550 1 */
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#ifdef DEBUG_NS16550
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#define DPRINTF(a) printf a
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#else
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#define DPRINTF(a)
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#endif
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#define COM_BASE        CONFIG_NS16550_BASE
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#define COM_IRQ                CONFIG_NS16550_IRQ
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/* Register offsets */
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#define COM_RBR                (COM_BASE + 0x00)        /* receive buffer register */
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#define COM_THR                (COM_BASE + 0x00)        /* transmit holding register */
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#define COM_IER                (COM_BASE + 0x01)        /* interrupt enable register */
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#define COM_FCR                (COM_BASE + 0x02)        /* FIFO control register */
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#define COM_IIR                (COM_BASE + 0x02)        /* interrupt identification register */
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#define COM_LCR                (COM_BASE + 0x03)        /* line control register */
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#define COM_MCR                (COM_BASE + 0x04)        /* modem control register */
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#define COM_LSR                (COM_BASE + 0x05)        /* line status register */
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#define COM_MSR                (COM_BASE + 0x06)        /* modem status register */
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#define COM_DLL                (COM_BASE + 0x00)        /* divisor latch LSB (LCR[7] = 1) */
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#define COM_DLM                (COM_BASE + 0x01)        /* divisor latch MSB (LCR[7] = 1) */
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/* Interrupt enable register */
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#define        IER_RDA                0x01        /* enable receive data available */
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#define        IER_THRE        0x02        /* enable transmitter holding register empty */
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#define        IER_RLS                0x04        /* enable recieve line status */
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#define        IER_RMS                0x08        /* enable receive modem status */
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/* Interrupt identification register */
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#define        IIR_MSR                0x00        /* modem status change */
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#define        IIR_IP                0x01        /* 0 when interrupt pending */
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#define        IIR_TXB                0x02        /* transmitter holding register empty */
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#define        IIR_RXB                0x04        /* received data available */
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#define        IIR_LSR                0x06        /* line status change */
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#define        IIR_MASK        0x07        /* mask off just the meaningful bits */
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/* line status register */
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#define        LSR_RCV_FIFO        0x80
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#define        LSR_TSRE        0x40        /* Transmitter empty: byte sent */
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#define        LSR_TXRDY        0x20        /* Transmitter buffer empty */
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#define        LSR_BI                0x10        /* Break detected */
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#define        LSR_FE                0x08        /* Framing error: bad stop bit */
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#define        LSR_PE                0x04        /* Parity error */
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#define        LSR_OE                0x02        /* Overrun, lost incoming byte */
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#define        LSR_RXRDY        0x01        /* Byte ready in Receive Buffer */
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#define        LSR_RCV_MASK        0x1f        /* Mask for incoming data or error */
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/* Forward functions */
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static int        ns16550_probe(struct driver *);
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static int        ns16550_init(struct driver *);
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static void        ns16550_xmt_char(struct serial_port *, char);
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static char        ns16550_rcv_char(struct serial_port *);
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static void        ns16550_set_poll(struct serial_port *, int);
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static void        ns16550_start(struct serial_port *);
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static void        ns16550_stop(struct serial_port *);
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struct driver ns16550_driver = {
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        /* name */        "ns16550",
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        /* devops */        NULL,
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        /* devsz */        0,
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        /* flags */        0,
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        /* probe */        ns16550_probe,
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        /* init */        ns16550_init,
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        /* unload */        NULL,
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};
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static struct serial_ops ns16550_ops = {
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        /* xmt_char */        ns16550_xmt_char,
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        /* rcv_char */        ns16550_rcv_char,
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        /* set_poll */        ns16550_set_poll,
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        /* start */        ns16550_start,
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        /* stop */        ns16550_stop,
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};
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static struct serial_port ns16550_port;
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static void
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ns16550_xmt_char(struct serial_port *sp, char c)
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{
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        while (!(bus_read_8(COM_LSR) & LSR_TXRDY))
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                ;
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        bus_write_8(COM_THR, c);
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}
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static char
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ns16550_rcv_char(struct serial_port *sp)
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{
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        while (!(bus_read_8(COM_LSR) & LSR_RXRDY))
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                ;
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        return bus_read_8(COM_RBR);
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}
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static void
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ns16550_set_poll(struct serial_port *sp, int on)
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{
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        if (on) {
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                /* Disable interrupt for polling mode. */
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                bus_write_8(COM_IER, 0x00);
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        } else {
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                /* enable interrupt again */
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                bus_write_8(COM_IER, IER_RDA|IER_THRE|IER_RLS);
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        }
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}
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static int
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ns16550_isr(void *arg)
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{
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        struct serial_port *sp = arg;
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        switch (bus_read_8(COM_IIR) & IIR_MASK) {
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        case IIR_MSR:                /* Modem status change */
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                break;
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        case IIR_LSR:                /* Line status change */
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                bus_read_8(COM_LSR);
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                break;
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        case IIR_TXB:                /* Transmitter holding register empty */
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                serial_xmt_done(sp);
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                break;
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        case IIR_RXB:                /* Received data available */
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                bus_read_8(COM_LSR);
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                serial_rcv_char(sp, bus_read_8(COM_RBR));
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                break;
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        }
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        return 0;
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}
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static void
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ns16550_start(struct serial_port *sp)
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{
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        int s;
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        bus_write_8(COM_IER, 0x00);        /* Disable interrupt */
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        bus_write_8(COM_LCR, 0x80);        /* Access baud rate */
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        bus_write_8(COM_DLL, 0x01);        /* 115200 baud */
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        bus_write_8(COM_DLM, 0x00);
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        bus_write_8(COM_LCR, 0x03);        /* N, 8, 1 */
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        bus_write_8(COM_FCR, 0x06);        /* Disable & clear FIFO */
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        sp->irq = irq_attach(COM_IRQ, IPL_COMM, 0, ns16550_isr,
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                             IST_NONE, sp);
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        s = splhigh();
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        bus_write_8(COM_MCR, 0x0b);  /* Enable OUT2 interrupt */
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        bus_write_8(COM_IER, IER_RDA|IER_THRE|IER_RLS);  /* Enable interrupt */
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        bus_read_8(COM_IIR);
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        splx(s);
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}
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static void
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ns16550_stop(struct serial_port *sp)
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{
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        /* Disable all interrupts */
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        bus_write_8(COM_IER, 0x00);
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}
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static int
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ns16550_probe(struct driver *self)
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{
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        if (bus_read_8(COM_LSR) == 0xff)
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                return ENXIO;        /* Port is disabled */
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        return 0;
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}
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static int
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ns16550_init(struct driver *self)
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{
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        serial_attach(&ns16550_ops, &ns16550_port);
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        return 0;
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}