xref: /freebsd-13.1/sys/dev/uart/uart_core.c (revision 27d5dc18)

/*
 * Copyright (c) 2003 Marcel Moolenaar
 * 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("$FreeBSD$");

#ifndef KLD_MODULE
#include "opt_comconsole.h"
#include "opt_ddb.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/cons.h>
#include <sys/fcntl.h>
#include <sys/interrupt.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/reboot.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include <sys/termios.h>
#include <sys/tty.h>
#include <machine/resource.h>
#include <machine/stdarg.h>

#include <ddb/ddb.h>

#include <dev/uart/uart.h>
#include <dev/uart/uart_bus.h>
#include <dev/uart/uart_cpu.h>

#include "uart_if.h"

devclass_t uart_devclass;
char uart_driver_name[] = "uart";

SLIST_HEAD(uart_devinfo_list, uart_devinfo) uart_sysdevs =
    SLIST_HEAD_INITIALIZER(uart_sysdevs);

MALLOC_DEFINE(M_UART, "UART", "UART driver");

void
uart_add_sysdev(struct uart_devinfo *di)
{
	SLIST_INSERT_HEAD(&uart_sysdevs, di, next);
}

/*
 * A break condition has been detected. We treat the break condition as
 * a special case that should not happen during normal operation. When
 * the break condition is to be passed to higher levels in the form of
 * a NUL character, we really want the break to be in the right place in
 * the input stream. The overhead to achieve that is not in relation to
 * the exceptional nature of the break condition, so we permit ourselves
 * to be sloppy.
 */
static void
uart_intr_break(struct uart_softc *sc)
{

#if defined(DDB) && defined(BREAK_TO_DEBUGGER)
	if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
		breakpoint();
		return;
	}
#endif
	if (sc->sc_opened)
		atomic_set_32(&sc->sc_ttypend, UART_IPEND_BREAK);
}

/*
 * Handle a receiver overrun situation. We lost at least 1 byte in the
 * input stream and it's our job to contain the situation. We grab as
 * much of the data we can, but otherwise flush the receiver FIFO to
 * create some breathing room. The net effect is that we avoid the
 * overrun condition to happen for the next X characters, where X is
 * related to the FIFO size at the cost of loosing data right away.
 * So, instead of having multiple overrun interrupts in close proximity
 * to each other and possibly pessimizing UART interrupt latency for
 * other UARTs in a multiport configuration, we create a longer segment
 * of missing characters by freeing up the FIFO.
 * Each overrun condition is marked in the input buffer by a token. The
 * token represents the loss of at least one, but possible more bytes in
 * the input stream.
 */
static void
uart_intr_overrun(struct uart_softc *sc)
{

	if (sc->sc_opened) {
		UART_RECEIVE(sc);
		if (uart_rx_put(sc, UART_STAT_OVERRUN))
			sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN;
		atomic_set_32(&sc->sc_ttypend, UART_IPEND_RXREADY);
	}
	UART_FLUSH(sc, UART_FLUSH_RECEIVER);
}

/*
 * Received data ready.
 */
static void
uart_intr_rxready(struct uart_softc *sc)
{
	int rxp;

	rxp = sc->sc_rxput;
	UART_RECEIVE(sc);
#if defined(DDB) && defined(ALT_BREAK_TO_DEBUGGER)
	if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
		while (rxp != sc->sc_rxput) {
			if (db_alt_break(sc->sc_rxbuf[rxp++], &sc->sc_altbrk))
				breakpoint();
			if (rxp == sc->sc_rxbufsz)
				rxp = 0;
		}
	}
#endif
	if (sc->sc_opened)
		atomic_set_32(&sc->sc_ttypend, UART_IPEND_RXREADY);
	else
		sc->sc_rxput = sc->sc_rxget;	/* Ignore received data. */
}

/*
 * Line or modem status change (OOB signalling).
 * We pass the signals to the software interrupt handler for further
 * processing. Note that we merge the delta bits, but set the state
 * bits. This is to avoid loosing state transitions due to having more
 * than 1 hardware interrupt between software interrupts.
 */
static void
uart_intr_sigchg(struct uart_softc *sc)
{
	int new, old, sig;

	sig = UART_GETSIG(sc);
	do {
		old = sc->sc_ttypend;
		new = old & ~UART_SIGMASK_STATE;
		new |= sig & UART_IPEND_SIGMASK;
		new |= UART_IPEND_SIGCHG;
	} while (!atomic_cmpset_32(&sc->sc_ttypend, old, new));
}

/*
 * The transmitter can accept more data.
 */
static void
uart_intr_txidle(struct uart_softc *sc)
{
	if (sc->sc_txbusy) {
		sc->sc_txbusy = 0;
		atomic_set_32(&sc->sc_ttypend, UART_IPEND_TXIDLE);
	}
}

static void
uart_intr(void *arg)
{
	struct uart_softc *sc = arg;
	int ipend;

	if (sc->sc_leaving)
		return;

	ipend = UART_IPEND(sc);
	if (ipend & UART_IPEND_OVERRUN)
		uart_intr_overrun(sc);
	if (ipend & UART_IPEND_BREAK)
		uart_intr_break(sc);
	if (ipend & UART_IPEND_RXREADY)
		uart_intr_rxready(sc);
	if (ipend & UART_IPEND_SIGCHG)
		uart_intr_sigchg(sc);
	if (ipend & UART_IPEND_TXIDLE)
		uart_intr_txidle(sc);

	if (sc->sc_opened && sc->sc_ttypend != 0)
		swi_sched(sc->sc_softih, 0);
}

int
uart_bus_probe(device_t dev, int regshft, int rclk, int rid)
{
	struct uart_softc *sc;
	struct uart_devinfo *sysdev;
	int error;

	/*
	 * Initialize the instance. Note that the instance (=softc) does
	 * not necessarily match the hardware specific softc. We can't do
	 * anything about it now, because we may not attach to the device.
	 * Hardware drivers cannot use any of the class specific fields
	 * while probing.
	 */
	sc = device_get_softc(dev);
	kobj_init((kobj_t)sc, (kobj_class_t)sc->sc_class);
	sc->sc_dev = dev;
	if (device_get_desc(dev) == NULL)
		device_set_desc(dev, sc->sc_class->name);

	/*
	 * Allocate the register resource. We assume that all UARTs have
	 * a single register window in either I/O port space or memory
	 * mapped I/O space. Any UART that needs multiple windows will
	 * consequently not be supported by this driver as-is. We try I/O
	 * port space first because that's the common case.
	 */
	sc->sc_rrid = rid;
	sc->sc_rtype = SYS_RES_IOPORT;
	sc->sc_rres = bus_alloc_resource(dev, sc->sc_rtype, &sc->sc_rrid,
	    0, ~0, sc->sc_class->uc_range, RF_ACTIVE);
	if (sc->sc_rres == NULL) {
		sc->sc_rrid = rid;
		sc->sc_rtype = SYS_RES_MEMORY;
		sc->sc_rres = bus_alloc_resource(dev, sc->sc_rtype,
		    &sc->sc_rrid, 0, ~0, sc->sc_class->uc_range, RF_ACTIVE);
		if (sc->sc_rres == NULL)
			return (ENXIO);
	}

	/*
	 * Fill in the bus access structure and compare this device with
	 * a possible console device and/or a debug port. We set the flags
	 * in the softc so that the hardware dependent probe can adjust
	 * accordingly. In general, you don't want to permanently disrupt
	 * console I/O.
	 */
	sc->sc_bas.bsh = rman_get_bushandle(sc->sc_rres);
	sc->sc_bas.bst = rman_get_bustag(sc->sc_rres);
	sc->sc_bas.regshft = regshft;
	sc->sc_bas.rclk = (rclk == 0) ? sc->sc_class->uc_rclk : rclk;

	SLIST_FOREACH(sysdev, &uart_sysdevs, next) {
		if (uart_cpu_eqres(&sc->sc_bas, &sysdev->bas)) {
			/* XXX check if ops matches class. */
			sc->sc_sysdev = sysdev;
			break;
		}
	}

	error = UART_PROBE(sc);
	bus_release_resource(dev, sc->sc_rtype, sc->sc_rrid, sc->sc_rres);
	return (error);
}

int
uart_bus_attach(device_t dev)
{
	struct uart_softc *sc, *sc0;
	const char *sep;
	int error;

	/*
	 * The sc_class field defines the type of UART we're going to work
	 * with and thus the size of the softc. Replace the generic softc
	 * with one that matches the UART now that we're certain we handle
	 * the device.
	 */
	sc0 = device_get_softc(dev);
	if (sc0->sc_class->size > sizeof(*sc)) {
		sc = malloc(sc0->sc_class->size, M_UART, M_WAITOK|M_ZERO);
		bcopy(sc0, sc, sizeof(*sc));
		device_set_softc(dev, sc);
	} else
		sc = sc0;

	/*
	 * Protect ourselves against interrupts while we're not completely
	 * finished attaching and initializing. We don't expect interrupts
	 * until after UART_ATTACH() though.
	 */
	sc->sc_leaving = 1;

	/*
	 * Re-allocate. We expect that the softc contains the information
	 * collected by uart_bus_probe() intact.
	 */
	sc->sc_rres = bus_alloc_resource(dev, sc->sc_rtype, &sc->sc_rrid,
	    0, ~0, sc->sc_class->uc_range, RF_ACTIVE);
	if (sc->sc_rres == NULL)
		return (ENXIO);

	sc->sc_irid = 0;
	sc->sc_ires = bus_alloc_resource(dev, SYS_RES_IRQ, &sc->sc_irid,
	    0, ~0, 1, RF_ACTIVE);
	if (sc->sc_ires != NULL) {
		error = BUS_SETUP_INTR(device_get_parent(dev), dev,
		    sc->sc_ires, INTR_TYPE_TTY | INTR_FAST, uart_intr,
		    sc, &sc->sc_icookie);
		if (error)
			error = BUS_SETUP_INTR(device_get_parent(dev), dev,
			    sc->sc_ires, INTR_TYPE_TTY, uart_intr, sc,
			    &sc->sc_icookie);
		else
			sc->sc_fastintr = 1;

		if (error) {
			device_printf(dev, "could not activate interrupt\n");
			bus_release_resource(dev, SYS_RES_IRQ, sc->sc_irid,
			    sc->sc_ires);
			sc->sc_ires = NULL;
		}
	}
	if (sc->sc_ires == NULL) {
		/* XXX no interrupt resource. Force polled mode. */
		sc->sc_polled = 1;
	}

	sc->sc_rxbufsz = IBUFSIZ;
	sc->sc_rxbuf = malloc(sc->sc_rxbufsz * sizeof(*sc->sc_rxbuf),
	    M_UART, M_WAITOK);
	sc->sc_txbuf = malloc(sc->sc_txfifosz * sizeof(*sc->sc_txbuf),
	    M_UART, M_WAITOK);

	error = UART_ATTACH(sc);
	if (error)
		goto fail;

	if (sc->sc_hwiflow || sc->sc_hwoflow) {
		sep = "";
		device_print_prettyname(dev);
		if (sc->sc_hwiflow) {
			printf("%sRTS iflow", sep);
			sep = ", ";
		}
		if (sc->sc_hwoflow) {
			printf("%sCTS oflow", sep);
			sep = ", ";
		}
		printf("\n");
	}

	if (bootverbose && (sc->sc_fastintr || sc->sc_polled)) {
		sep = "";
		device_print_prettyname(dev);
		if (sc->sc_fastintr) {
			printf("%sfast interrupt", sep);
			sep = ", ";
		}
		if (sc->sc_polled) {
			printf("%spolled mode", sep);
			sep = ", ";
		}
		printf("\n");
	}

	if (sc->sc_sysdev != NULL) {
		switch (sc->sc_sysdev->type) {
		case UART_DEV_CONSOLE:
			device_printf(dev, "console");
			break;
		case UART_DEV_DBGPORT:
			device_printf(dev, "debug port");
			break;
		case UART_DEV_KEYBOARD:
			device_printf(dev, "keyboard");
			break;
		default:
			device_printf(dev, "unknown system device");
			break;
		}
		printf(" (%d,%c,%d,%d)\n", sc->sc_sysdev->baudrate,
		    "noems"[sc->sc_sysdev->parity], sc->sc_sysdev->databits,
		    sc->sc_sysdev->stopbits);
	}

	error = (sc->sc_sysdev != NULL && sc->sc_sysdev->attach != NULL)
	    ? (*sc->sc_sysdev->attach)(sc) : uart_tty_attach(sc);
	if (error)
		goto fail;

	sc->sc_leaving = 0;
	uart_intr(sc);
	return (0);

 fail:
	free(sc->sc_txbuf, M_UART);
	free(sc->sc_rxbuf, M_UART);

	if (sc->sc_ires != NULL) {
		bus_teardown_intr(dev, sc->sc_ires, sc->sc_icookie);
		bus_release_resource(dev, SYS_RES_IRQ, sc->sc_irid,
		    sc->sc_ires);
	}
	bus_release_resource(dev, sc->sc_rtype, sc->sc_rrid, sc->sc_rres);

	return (error);
}

int
uart_bus_detach(device_t dev)
{
	struct uart_softc *sc;

	sc = device_get_softc(dev);

	sc->sc_leaving = 1;

	UART_DETACH(sc);

	if (sc->sc_sysdev != NULL && sc->sc_sysdev->detach != NULL)
		(*sc->sc_sysdev->detach)(sc);
	else
		uart_tty_detach(sc);

	free(sc->sc_txbuf, M_UART);
	free(sc->sc_rxbuf, M_UART);

	if (sc->sc_ires != NULL) {
		bus_teardown_intr(dev, sc->sc_ires, sc->sc_icookie);
		bus_release_resource(dev, SYS_RES_IRQ, sc->sc_irid,
		    sc->sc_ires);
	}
	bus_release_resource(dev, sc->sc_rtype, sc->sc_rrid, sc->sc_rres);

	if (sc->sc_class->size > sizeof(*sc)) {
		device_set_softc(dev, NULL);
		free(sc, M_UART);
	} else
		device_set_softc(dev, NULL);

	return (0);
}