freebsd-skq/sys/arm/at91/uart_dev_at91usart.c

/*-
 * Copyright (c) 2005 M. Warner Losh
 * Copyright (c) 2005 Olivier Houchard
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_comconsole.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/cons.h>
#include <sys/tty.h>
#include <machine/bus.h>

#include <dev/uart/uart.h>
#include <dev/uart/uart_cpu.h>
#include <dev/uart/uart_bus.h>
#include <arm/at91/at91rm92reg.h>
#include <arm/at91/at91_usartreg.h>
#include <arm/at91/at91_pdcreg.h>

#include "uart_if.h"

#define DEFAULT_RCLK		AT91C_MASTER_CLOCK
#define	USART_BUFFER_SIZE	128

/*
 * High-level UART interface.
 */
struct at91_usart_rx {
	bus_addr_t	pa;
	uint8_t		buffer[USART_BUFFER_SIZE];
	bus_dmamap_t	map;
};

struct at91_usart_softc {
	struct uart_softc base;
	bus_dma_tag_t dmatag;		/* bus dma tag for mbufs */
	bus_dmamap_t tx_map;
	uint32_t flags;
#define HAS_TIMEOUT	1	
	struct at91_usart_rx ping_pong[2];
	struct at91_usart_rx *ping;
	struct at91_usart_rx *pong;
};

#define	RD4(bas, reg)		\
	bus_space_read_4((bas)->bst, (bas)->bsh, uart_regofs(bas, reg))
#define	WR4(bas, reg, value)	\
	bus_space_write_4((bas)->bst, (bas)->bsh, uart_regofs(bas, reg), value)

#define	SIGCHG(c, i, s, d)				\
	do {						\
		if (c) {				\
			i |= (i & s) ? s : s | d;	\
		} else {				\
			i = (i & s) ? (i & ~s) | d : i;	\
		}					\
	} while (0);

#define BAUD2DIVISOR(b) \
	((((DEFAULT_RCLK * 10) / ((b) * 16)) + 5) / 10)

/*
 * Low-level UART interface.
 */
static int at91_usart_probe(struct uart_bas *bas);
static void at91_usart_init(struct uart_bas *bas, int, int, int, int);
static void at91_usart_term(struct uart_bas *bas);
static void at91_usart_putc(struct uart_bas *bas, int);
static int at91_usart_poll(struct uart_bas *bas);
static int at91_usart_getc(struct uart_bas *bas, struct mtx *mtx);

extern SLIST_HEAD(uart_devinfo_list, uart_devinfo) uart_sysdevs;

static int
at91_usart_param(struct uart_bas *bas, int baudrate, int databits,
    int stopbits, int parity)
{
	uint32_t mr;

	/*
	 * Assume 3-write RS-232 configuration.
	 * XXX Not sure how uart will present the other modes to us, so
	 * XXX they are unimplemented.  maybe ioctl?
	 */
	mr = USART_MR_MODE_NORMAL;
	mr |= USART_MR_USCLKS_MCK;	/* Assume MCK */

	/*
	 * Or in the databits requested
	 */
	if (databits < 9)
		mr &= ~USART_MR_MODE9;
	switch (databits) {
	case 5:
		mr |= USART_MR_CHRL_5BITS;
		break;
	case 6:
		mr |= USART_MR_CHRL_6BITS;
		break;
	case 7:
		mr |= USART_MR_CHRL_7BITS;
		break;
	case 8:
		mr |= USART_MR_CHRL_8BITS;
		break;
	case 9:
		mr |= USART_MR_CHRL_8BITS | USART_MR_MODE9;
		break;
	default:
		return (EINVAL);
	}

	/*
	 * Or in the parity
	 */
	switch (parity) {
	case UART_PARITY_NONE:
		mr |= USART_MR_PAR_NONE;
		break;
	case UART_PARITY_ODD:
		mr |= USART_MR_PAR_ODD;
		break;
	case UART_PARITY_EVEN:
		mr |= USART_MR_PAR_EVEN;
		break;
	case UART_PARITY_MARK:
		mr |= USART_MR_PAR_MARK;
		break;
	case UART_PARITY_SPACE:
		mr |= USART_MR_PAR_SPACE;
		break;
	default:
		return (EINVAL);
	}

	/*
	 * Or in the stop bits.  Note: The hardware supports 1.5 stop
	 * bits in async mode, but there's no way to specify that
	 * AFAICT.  Instead, rely on the convention documented at
	 * http://www.lammertbies.nl/comm/info/RS-232_specs.html which
	 * states that 1.5 stop bits are used for 5 bit bytes and
	 * 2 stop bits only for longer bytes.
	 */
	if (stopbits == 1)
		mr |= USART_MR_NBSTOP_1;
	else if (databits > 5)
		mr |= USART_MR_NBSTOP_2;
	else
		mr |= USART_MR_NBSTOP_1_5;

	/*
	 * We want normal plumbing mode too, none of this fancy
	 * loopback or echo mode.
	 */
	mr |= USART_MR_CHMODE_NORMAL;

	mr &= ~USART_MR_MSBF;	/* lsb first */
	mr &= ~USART_MR_CKLO_SCK;	/* Don't drive SCK */

	WR4(bas, USART_MR, mr);

	/*
	 * Set the baud rate
	 */
	WR4(bas, USART_BRGR, BAUD2DIVISOR(baudrate));

	/* XXX Need to take possible synchronous mode into account */
	return (0);
}

struct uart_ops at91_usart_ops = {
	.probe = at91_usart_probe,
	.init = at91_usart_init,
	.term = at91_usart_term,
	.putc = at91_usart_putc,
	.poll = at91_usart_poll,
	.getc = at91_usart_getc,
};

static int
at91_usart_probe(struct uart_bas *bas)
{
	/* We know that this is always here */
	return (0);
}

/*
 * Initialize this device for use as a console.
 */
static void
at91_usart_init(struct uart_bas *bas, int baudrate, int databits, int stopbits,
    int parity)
{

	at91_usart_param(bas, baudrate, databits, stopbits, parity);

	/* Reset the rx and tx buffers and turn on rx and tx */
	WR4(bas, USART_CR, USART_CR_RSTSTA | USART_CR_RSTRX | USART_CR_RSTTX);
	WR4(bas, USART_CR, USART_CR_RXEN | USART_CR_TXEN);
	WR4(bas, USART_IDR, 0xffffffff);
}

/*
 * Free resources now that we're no longer the console.  This appears to
 * be never called, and I'm unsure quite what to do if I am called.
 */
static void
at91_usart_term(struct uart_bas *bas)
{
	/* XXX */
}

/*
 * Put a character of console output (so we do it here polling rather than
 * interrutp driven).
 */
static void
at91_usart_putc(struct uart_bas *bas, int c)
{

    while (!(RD4(bas, USART_CSR) & USART_CSR_TXRDY))
		continue;
	WR4(bas, USART_THR, c);
}

/*
 * Poll for a character available
 */
static int
at91_usart_poll(struct uart_bas *bas)
{

	if (!(RD4(bas, USART_CSR) & USART_CSR_RXRDY))
		return (-1);
	return (RD4(bas, USART_RHR) & 0xff);
}

/*
 * Block waiting for a character.
 */
static int
at91_usart_getc(struct uart_bas *bas, struct mtx *mtx)
{
	int c;

	while (!(RD4(bas, USART_CSR) & USART_CSR_RXRDY))
		continue;
	c = RD4(bas, USART_RHR);
	c &= 0xff;
	return (c);
}

static int at91_usart_bus_probe(struct uart_softc *sc);
static int at91_usart_bus_attach(struct uart_softc *sc);
static int at91_usart_bus_flush(struct uart_softc *, int);
static int at91_usart_bus_getsig(struct uart_softc *);
static int at91_usart_bus_ioctl(struct uart_softc *, int, intptr_t);
static int at91_usart_bus_ipend(struct uart_softc *);
static int at91_usart_bus_param(struct uart_softc *, int, int, int, int);
static int at91_usart_bus_receive(struct uart_softc *);
static int at91_usart_bus_setsig(struct uart_softc *, int);
static int at91_usart_bus_transmit(struct uart_softc *);

static kobj_method_t at91_usart_methods[] = {
	KOBJMETHOD(uart_probe,		at91_usart_bus_probe),
	KOBJMETHOD(uart_attach, 	at91_usart_bus_attach),
	KOBJMETHOD(uart_flush,		at91_usart_bus_flush),
	KOBJMETHOD(uart_getsig,		at91_usart_bus_getsig),
	KOBJMETHOD(uart_ioctl,		at91_usart_bus_ioctl),
	KOBJMETHOD(uart_ipend,		at91_usart_bus_ipend),
	KOBJMETHOD(uart_param,		at91_usart_bus_param),
	KOBJMETHOD(uart_receive,	at91_usart_bus_receive),
	KOBJMETHOD(uart_setsig,		at91_usart_bus_setsig),
	KOBJMETHOD(uart_transmit,	at91_usart_bus_transmit),
	
	{ 0, 0 }
};

int
at91_usart_bus_probe(struct uart_softc *sc)
{
	return (0);
}

#ifndef SKYEYE_WORKAROUNDS
static void
at91_getaddr(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
{
	if (error != 0)
		return;
	*(bus_addr_t *)arg = segs[0].ds_addr;
}
#endif

static int
at91_usart_bus_attach(struct uart_softc *sc)
{
	int err, i;
	uint32_t cr;
	struct at91_usart_softc *atsc;

	atsc = (struct at91_usart_softc *)sc;

	/*
	 * See if we have a TIMEOUT bit.  We disable all interrupts as
	 * a side effect.  Boot loaders may have enabled them.  Since
	 * a TIMEOUT interrupt can't happen without other setup, the
	 * apparent race here can't actually happen.
	 */
	WR4(&sc->sc_bas, USART_IDR, 0xffffffff);
	WR4(&sc->sc_bas, USART_IER, USART_CSR_TIMEOUT);
	if (RD4(&sc->sc_bas, USART_IMR) & USART_CSR_TIMEOUT)
		atsc->flags |= HAS_TIMEOUT;
	WR4(&sc->sc_bas, USART_IDR, 0xffffffff);

	sc->sc_txfifosz = USART_BUFFER_SIZE;
	sc->sc_rxfifosz = USART_BUFFER_SIZE;
	sc->sc_hwiflow = 0;

	/*
	 * Allocate DMA tags and maps
	 */
	err = bus_dma_tag_create(NULL, 1, 0, BUS_SPACE_MAXADDR_32BIT,
	    BUS_SPACE_MAXADDR, NULL, NULL, USART_BUFFER_SIZE, 1,
	    USART_BUFFER_SIZE, BUS_DMA_ALLOCNOW, NULL, NULL, &atsc->dmatag);
	if (err != 0)
		goto errout;
	err = bus_dmamap_create(atsc->dmatag, 0, &atsc->tx_map);
	if (err != 0)
		goto errout;
	if (atsc->flags & HAS_TIMEOUT) {
		for (i = 0; i < 2; i++) {
			err = bus_dmamap_create(atsc->dmatag, 0,
			    &atsc->ping_pong[i].map);
			if (err != 0)
				goto errout;
			err = bus_dmamap_load(atsc->dmatag,
			    atsc->ping_pong[i].map,
			    atsc->ping_pong[i].buffer, sc->sc_rxfifosz,
			    at91_getaddr, &atsc->ping_pong[i].pa, 0);
			if (err != 0)
				goto errout;
			bus_dmamap_sync(atsc->dmatag, atsc->ping_pong[i].map,
			    BUS_DMASYNC_PREREAD);
		}
		atsc->ping = &atsc->ping_pong[0];
		atsc->pong = &atsc->ping_pong[1];
	}

	/*
	 * Prime the pump with the RX buffer.  We use two 64 byte bounce
	 * buffers here to avoid data overflow.
	 */

	/* Turn on rx and tx */
	cr = USART_CR_RSTSTA | USART_CR_RSTRX | USART_CR_RSTTX;
	WR4(&sc->sc_bas, USART_CR, cr);
	WR4(&sc->sc_bas, USART_CR, USART_CR_RXEN | USART_CR_TXEN);

	/*
	 * Setup the PDC to receive data.  We use the ping-pong buffers
	 * so that we can more easily bounce between the two and so that
	 * we get an interrupt 1/2 way through the software 'fifo' we have
	 * to avoid overruns.
	 */
	if (atsc->flags & HAS_TIMEOUT) {
		WR4(&sc->sc_bas, PDC_RPR, atsc->ping->pa);
		WR4(&sc->sc_bas, PDC_RCR, sc->sc_rxfifosz);
		WR4(&sc->sc_bas, PDC_RNPR, atsc->pong->pa);
		WR4(&sc->sc_bas, PDC_RNCR, sc->sc_rxfifosz);
		WR4(&sc->sc_bas, PDC_PTCR, PDC_PTCR_RXTEN);

		/* Set the receive timeout to be 1.5 character times. */
		WR4(&sc->sc_bas, USART_RTOR, 12);
		WR4(&sc->sc_bas, USART_CR, USART_CR_STTTO);
		WR4(&sc->sc_bas, USART_IER, USART_CSR_TIMEOUT |
		    USART_CSR_RXBUFF | USART_CSR_ENDRX);
	} else {
		WR4(&sc->sc_bas, USART_IER, USART_CSR_RXRDY);
	}
	WR4(&sc->sc_bas, USART_IER, USART_CSR_RXBRK);
errout:;
	// XXX bad
	return (err);
}

static int
at91_usart_bus_transmit(struct uart_softc *sc)
{
#ifndef SKYEYE_WORKAROUNDS
	bus_addr_t addr;
#endif
	struct at91_usart_softc *atsc;

	atsc = (struct at91_usart_softc *)sc;
#ifndef SKYEYE_WORKAROUNDS
	if (bus_dmamap_load(atsc->dmatag, atsc->tx_map, sc->sc_txbuf,
	    sc->sc_txdatasz, at91_getaddr, &addr, 0) != 0)
		return (EAGAIN);
	bus_dmamap_sync(atsc->dmatag, atsc->tx_map, BUS_DMASYNC_PREWRITE);
#endif

	uart_lock(sc->sc_hwmtx);
	sc->sc_txbusy = 1;
#ifndef SKYEYE_WORKAROUNDS
	/*
	 * Setup the PDC to transfer the data and interrupt us when it
	 * is done.  We've already requested the interrupt.
	 */
	WR4(&sc->sc_bas, PDC_TPR, addr);
	WR4(&sc->sc_bas, PDC_TCR, sc->sc_txdatasz);
	WR4(&sc->sc_bas, PDC_PTCR, PDC_PTCR_TXTEN);
	WR4(&sc->sc_bas, USART_IER, USART_CSR_ENDTX);
	uart_unlock(sc->sc_hwmtx);
#else
	for (int i = 0; i < sc->sc_txdatasz; i++)
		at91_usart_putc(&sc->sc_bas, sc->sc_txbuf[i]);
	/*
	 * XXX: Gross hack : Skyeye doesn't raise an interrupt once the
	 * transfer is done, so simulate it.
	 */
	WR4(&sc->sc_bas, USART_IER, USART_CSR_TXRDY);
#endif
	return (0);
}
static int
at91_usart_bus_setsig(struct uart_softc *sc, int sig)
{
	uint32_t new, old, cr;
	struct uart_bas *bas;

	do {
		old = sc->sc_hwsig;
		new = old;
		if (sig & SER_DDTR)
			SIGCHG(sig & SER_DTR, new, SER_DTR, SER_DDTR);
		if (sig & SER_DRTS)
			SIGCHG(sig & SER_RTS, new, SER_RTS, SER_DRTS);
	} while (!atomic_cmpset_32(&sc->sc_hwsig, old, new));
	bas = &sc->sc_bas;
	uart_lock(sc->sc_hwmtx);
	cr = 0;
	if (new & SER_DTR)
		cr |= USART_CR_DTREN;
	else
		cr |= USART_CR_DTRDIS;
	if (new & SER_RTS)
		cr |= USART_CR_RTSEN;
	else
		cr |= USART_CR_RTSDIS;
	WR4(bas, USART_CR, cr);
	uart_unlock(sc->sc_hwmtx);
	return (0);
}
static int
at91_usart_bus_receive(struct uart_softc *sc)
{

	return (0);
}
static int
at91_usart_bus_param(struct uart_softc *sc, int baudrate, int databits,
    int stopbits, int parity)
{

	return (at91_usart_param(&sc->sc_bas, baudrate, databits, stopbits,
	    parity));
}

static __inline void
at91_rx_put(struct uart_softc *sc, int key)
{
#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
	if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
		if (kdb_alt_break(key, &sc->sc_altbrk))
			kdb_enter("Break sequence to console");
	}
#endif
	uart_rx_put(sc, key);	
}

static int
at91_usart_bus_ipend(struct uart_softc *sc)
{
	int csr = RD4(&sc->sc_bas, USART_CSR);
	int ipend = 0, i, len;
	struct at91_usart_softc *atsc;
	struct at91_usart_rx *p;

	atsc = (struct at91_usart_softc *)sc;	   
	if (csr & USART_CSR_ENDTX) {
		bus_dmamap_sync(atsc->dmatag, atsc->tx_map,
		    BUS_DMASYNC_POSTWRITE);
		bus_dmamap_unload(atsc->dmatag, atsc->tx_map);
	}
	uart_lock(sc->sc_hwmtx);
	if (csr & USART_CSR_TXRDY) {
		if (sc->sc_txbusy)
			ipend |= SER_INT_TXIDLE;
		WR4(&sc->sc_bas, USART_IDR, USART_CSR_TXRDY);
	}
	if (csr & USART_CSR_ENDTX) {
		if (sc->sc_txbusy)
			ipend |= SER_INT_TXIDLE;
		WR4(&sc->sc_bas, USART_IDR, USART_CSR_ENDTX);
	}

	/*
	 * Due to the contraints of the DMA engine present in the
	 * atmel chip, I can't just say I have a rx interrupt pending
	 * and do all the work elsewhere.  I need to look at the CSR
	 * bits right now and do things based on them to avoid races.
	 */
	if ((atsc->flags & HAS_TIMEOUT) && (csr & USART_CSR_RXBUFF)) {
		// Have a buffer overflow.  Copy all data from both
		// ping and pong.  Insert overflow character.  Reset
		// ping and pong and re-enable the PDC to receive
		// characters again.
		bus_dmamap_sync(atsc->dmatag, atsc->ping->map,
		    BUS_DMASYNC_POSTREAD);
		bus_dmamap_sync(atsc->dmatag, atsc->pong->map,
		    BUS_DMASYNC_POSTREAD);
		for (i = 0; i < sc->sc_rxfifosz; i++)
			at91_rx_put(sc, atsc->ping->buffer[i]);
		for (i = 0; i < sc->sc_rxfifosz; i++)
			at91_rx_put(sc, atsc->pong->buffer[i]);
		uart_rx_put(sc, UART_STAT_OVERRUN);
		csr &= ~(USART_CSR_ENDRX | USART_CSR_TIMEOUT);
		WR4(&sc->sc_bas, PDC_RPR, atsc->ping->pa);
		WR4(&sc->sc_bas, PDC_RCR, sc->sc_rxfifosz);
		WR4(&sc->sc_bas, PDC_RNPR, atsc->pong->pa);
		WR4(&sc->sc_bas, PDC_RNCR, sc->sc_rxfifosz);
		WR4(&sc->sc_bas, PDC_PTCR, PDC_PTCR_RXTEN);
		ipend |= SER_INT_RXREADY;
	}
	if ((atsc->flags & HAS_TIMEOUT) && (csr & USART_CSR_ENDRX)) {
		// Shuffle data from 'ping' of ping pong buffer, but
		// leave current 'pong' in place, as it has become the
		// new 'ping'.  We need to copy data and setup the old
		// 'ping' as the new 'pong' when we're done.
		bus_dmamap_sync(atsc->dmatag, atsc->ping->map,
		    BUS_DMASYNC_POSTREAD);
		for (i = 0; i < sc->sc_rxfifosz; i++)
			at91_rx_put(sc, atsc->ping->buffer[i]);
		p = atsc->ping;
		atsc->ping = atsc->pong;
		atsc->pong = p;
		WR4(&sc->sc_bas, PDC_RNPR, atsc->pong->pa);
		WR4(&sc->sc_bas, PDC_RNCR, sc->sc_rxfifosz);
		ipend |= SER_INT_RXREADY;
	}
	if ((atsc->flags & HAS_TIMEOUT) && (csr & USART_CSR_TIMEOUT)) {
		// We have one partial buffer.  We need to stop the
		// PDC, get the number of characters left and from
		// that compute number of valid characters.  We then
		// need to reset ping and pong and reenable the PDC.
		// Not sure if there's a race here at fast baud rates
		// we need to worry about.
		WR4(&sc->sc_bas, PDC_PTCR, PDC_PTCR_RXTDIS);
		bus_dmamap_sync(atsc->dmatag, atsc->ping->map,
		    BUS_DMASYNC_POSTREAD);
		len = sc->sc_rxfifosz - RD4(&sc->sc_bas, PDC_RCR);
		for (i = 0; i < len; i++)
			at91_rx_put(sc, atsc->ping->buffer[i]);
		WR4(&sc->sc_bas, PDC_RPR, atsc->ping->pa);
		WR4(&sc->sc_bas, PDC_RCR, sc->sc_rxfifosz);
		WR4(&sc->sc_bas, USART_CR, USART_CR_STTTO);
		WR4(&sc->sc_bas, PDC_PTCR, PDC_PTCR_RXTEN);
		ipend |= SER_INT_RXREADY;
	}
	if (!(atsc->flags & HAS_TIMEOUT) && (csr & USART_CSR_RXRDY)) {
		// We have another charater in a device that doesn't support
		// timeouts, so we do it one character at a time.
		at91_rx_put(sc, RD4(&sc->sc_bas, USART_RHR) & 0xff);
		ipend |= SER_INT_RXREADY;
	}

	if (csr & USART_CSR_RXBRK) {
		unsigned int cr = USART_CR_RSTSTA;

		ipend |= SER_INT_BREAK;
		WR4(&sc->sc_bas, USART_CR, cr);
	}
	uart_unlock(sc->sc_hwmtx);
	return (ipend);
}
static int
at91_usart_bus_flush(struct uart_softc *sc, int what)
{
	return (0);
}

static int
at91_usart_bus_getsig(struct uart_softc *sc)
{
	uint32_t new, sig;
	uint8_t csr;

	uart_lock(sc->sc_hwmtx);
	csr = RD4(&sc->sc_bas, USART_CSR);
	sig = 0;
	if (csr & USART_CSR_CTS)
		sig |= SER_CTS;
	if (csr & USART_CSR_DCD)
		sig |= SER_DCD;
	if (csr & USART_CSR_DSR)
		sig |= SER_DSR;
	if (csr & USART_CSR_RI)
		sig |= SER_RI;
	new = sig & ~SER_MASK_DELTA;
	sc->sc_hwsig = new;
	uart_unlock(sc->sc_hwmtx);
	return (sig);
}

static int
at91_usart_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
{
	switch (request) {
	case UART_IOCTL_BREAK:
	case UART_IOCTL_IFLOW:
	case UART_IOCTL_OFLOW:
		break;
	case UART_IOCTL_BAUD:
		WR4(&sc->sc_bas, USART_BRGR, BAUD2DIVISOR(*(int *)data));
		return (0);
	}
	return (EINVAL);
}
struct uart_class at91_usart_class = {
	"at91_usart class",
	at91_usart_methods,
	sizeof(struct at91_usart_softc),
	.uc_range = 8,
	.uc_rclk = DEFAULT_RCLK
};