21 files changed, 184 insertions, 76 deletions

diff --git a/sys/arm/at91/uart_cpu_at91rm9200usart.c b/sys/arm/at91/uart_cpu_at91rm9200usart.c
index 75a053d0f091d..459badbd14082 100644
--- a/sys/arm/at91/uart_cpu_at91rm9200usart.c
+++ b/sys/arm/at91/uart_cpu_at91rm9200usart.c
@@ -43,7 +43,7 @@ __FBSDID("$FreeBSD$");
 bus_space_tag_t uart_bus_space_io;
 bus_space_tag_t uart_bus_space_mem;
 
-extern struct uart_ops at91_usart_ops;
+extern struct uart_class at91_usart_class;
 extern struct bus_space at91_bs_tag;
 
 int
@@ -55,7 +55,10 @@ uart_cpu_eqres(struct uart_bas *b1, struct uart_bas *b2)
 int
 uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
-	di->ops = at91_usart_ops;
+	struct uart_class *class;
+
+	class = &at91_usart_class;
+	di->ops = uart_getops(class);
 	di->bas.chan = 0;
 	di->bas.bst = &at91_bs_tag;
 	/* 
@@ -77,7 +80,5 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 	uart_bus_space_io = &at91_bs_tag;
 	uart_bus_space_mem = NULL;
 	/* Check the environment for overrides */
-	if (uart_getenv(devtype, di) == 0)
-		return (0);
-	return (0);
+	return (uart_getenv(devtype, di, class));
 }
diff --git a/sys/arm/at91/uart_dev_at91usart.c b/sys/arm/at91/uart_dev_at91usart.c
index a405aa3120101..88625899f1970 100644
--- a/sys/arm/at91/uart_dev_at91usart.c
+++ b/sys/arm/at91/uart_dev_at91usart.c
@@ -196,7 +196,7 @@ at91_usart_param(struct uart_bas *bas, int baudrate, int databits,
 	return (0);
 }
 
-struct uart_ops at91_usart_ops = {
+static struct uart_ops at91_usart_ops = {
 	.probe = at91_usart_probe,
 	.init = at91_usart_init,
 	.term = at91_usart_term,
@@ -662,10 +662,12 @@ at91_usart_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
 	}
 	return (EINVAL);
 }
+
 struct uart_class at91_usart_class = {
-	"at91_usart class",
+	"at91_usart",
 	at91_usart_methods,
 	sizeof(struct at91_usart_softc),
+	.uc_ops = &at91_usart_ops,
 	.uc_range = 8,
 	.uc_rclk = DEFAULT_RCLK
 };
diff --git a/sys/arm/sa11x0/uart_cpu_sa1110.c b/sys/arm/sa11x0/uart_cpu_sa1110.c
index d96dee309e4de..5d6a3c3bfe721 100644
--- a/sys/arm/sa11x0/uart_cpu_sa1110.c
+++ b/sys/arm/sa11x0/uart_cpu_sa1110.c
@@ -42,7 +42,7 @@ __FBSDID("$FreeBSD$");
 bus_space_tag_t uart_bus_space_io;
 bus_space_tag_t uart_bus_space_mem;
 
-extern struct uart_ops uart_sa1110_ops;
+extern struct uart_class uart_sa1110_class;
 
 vm_offset_t sa1110_uart_vaddr;
 
@@ -55,7 +55,8 @@ uart_cpu_eqres(struct uart_bas *b1, struct uart_bas *b2)
 int
 uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
-	di->ops = uart_sa1110_ops;
+
+	di->ops = uart_getops(&uart_sa1110_class);
 	di->bas.chan = 0;
 	di->bas.bst = &sa11x0_bs_tag;
 	di->bas.bsh = sa1110_uart_vaddr;
diff --git a/sys/arm/sa11x0/uart_dev_sa1110.c b/sys/arm/sa11x0/uart_dev_sa1110.c
index 0a36bca116255..35ff22bc00d31 100644
--- a/sys/arm/sa11x0/uart_dev_sa1110.c
+++ b/sys/arm/sa11x0/uart_dev_sa1110.c
@@ -57,7 +57,7 @@ static int sa1110_getc(struct uart_bas *bas, struct mtx *mtx);
 
 extern SLIST_HEAD(uart_devinfo_list, uart_devinfo) uart_sysdevs;
 
-struct uart_ops uart_sa1110_ops = {
+static struct uart_ops uart_sa1110_ops = {
 	.probe = sa1110_probe,
 	.init = sa1110_init,
 	.term = sa1110_term,
@@ -272,10 +272,12 @@ sa1110_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
 {
 	return (EINVAL);
 }
+
 struct uart_class uart_sa1110_class = {
-	"sa1110 class",
+	"sa1110",
 	sa1110_methods,
 	1,
+	.uc_ops = &uart_sa1110_ops,
 	.uc_range = 8,
 	.uc_rclk = 3686400
 };
diff --git a/sys/arm/xscale/i80321/uart_cpu_i80321.c b/sys/arm/xscale/i80321/uart_cpu_i80321.c
index 987422ee24d01..32dd463cfb47d 100644
--- a/sys/arm/xscale/i80321/uart_cpu_i80321.c
+++ b/sys/arm/xscale/i80321/uart_cpu_i80321.c
@@ -51,7 +51,7 @@ uart_cpu_eqres(struct uart_bas *b1, struct uart_bas *b2)
 int
 uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
-	di->ops = uart_ns8250_ops;
+	di->ops = uart_getops(&uart_ns8250_class);
 	di->bas.chan = 0;
 	di->bas.bst = &obio_bs_tag;
 	di->bas.regshft = 0;
diff --git a/sys/arm/xscale/ixp425/uart_cpu_ixp425.c b/sys/arm/xscale/ixp425/uart_cpu_ixp425.c
index e691968538c67..837e2711378cf 100644
--- a/sys/arm/xscale/ixp425/uart_cpu_ixp425.c
+++ b/sys/arm/xscale/ixp425/uart_cpu_ixp425.c
@@ -51,7 +51,7 @@ uart_cpu_eqres(struct uart_bas *b1, struct uart_bas *b2)
 int
 uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
-	di->ops = uart_ns8250_ops;
+	di->ops = uart_getops(&uart_ns8250_class);
 	di->bas.chan = 0;
 	di->bas.bst = &ixp425_a4x_bs_tag;
 	di->bas.regshft = 0;
diff --git a/sys/dev/uart/uart.h b/sys/dev/uart/uart.h
index da9bd1baf4d46..f4320d4c53ab0 100644
--- a/sys/dev/uart/uart.h
+++ b/sys/dev/uart/uart.h
@@ -60,6 +60,15 @@ struct uart_bas {
 	    BUS_SPACE_BARRIER_READ|BUS_SPACE_BARRIER_WRITE)
 
 /*
+ * UART device classes.
+ */
+struct uart_class;
+
+extern struct uart_class uart_ns8250_class __attribute__((weak));
+extern struct uart_class uart_sab82532_class __attribute__((weak));
+extern struct uart_class uart_z8530_class __attribute__((weak));
+
+/*
  * Device flags.
  */
 #define	UART_FLAGS_CONSOLE(f)		((f) & 0x10)
diff --git a/sys/dev/uart/uart_bus.h b/sys/dev/uart/uart_bus.h
index 5396515a8c910..7154d859026a0 100644
--- a/sys/dev/uart/uart_bus.h
+++ b/sys/dev/uart/uart_bus.h
@@ -67,14 +67,11 @@
  */
 struct uart_class {
 	KOBJ_CLASS_FIELDS;
+	struct uart_ops *uc_ops;	/* Low-level console operations. */
 	u_int	uc_range;		/* Bus space address range. */
 	u_int	uc_rclk;		/* Default rclk for this device. */
 };
 
-extern struct uart_class uart_ns8250_class;
-extern struct uart_class uart_sab82532_class;
-extern struct uart_class uart_z8530_class;
-
 struct uart_softc {
 	KOBJ_FIELDS;
 	struct uart_class *sc_class;
diff --git a/sys/dev/uart/uart_core.c b/sys/dev/uart/uart_core.c
index 6daf938c04823..f99127881e82b 100644
--- a/sys/dev/uart/uart_core.c
+++ b/sys/dev/uart/uart_core.c
@@ -70,6 +70,24 @@ uart_add_sysdev(struct uart_devinfo *di)
 	SLIST_INSERT_HEAD(&uart_sysdevs, di, next);
 }
 
+const char *
+uart_getname(struct uart_class *uc)
+{
+	return ((uc != NULL) ? uc->name : NULL);
+}
+
+struct uart_ops *
+uart_getops(struct uart_class *uc)
+{
+	return ((uc != NULL) ? uc->uc_ops : NULL);
+}
+
+int
+uart_getrange(struct uart_class *uc)
+{
+	return ((uc != NULL) ? uc->uc_range : 0);
+}
+
 /*
  * Schedule a soft interrupt. We do this on the 0 to !0 transition
  * of the TTY pending interrupt status.
@@ -293,6 +311,15 @@ uart_bus_probe(device_t dev, int regshft, int rclk, int rid, int chan)
 	struct uart_devinfo *sysdev;
 	int error;
 
+	sc = device_get_softc(dev);
+
+	/*
+	 * All uart_class references are weak. Check that the needed
+	 * class has been compiled-in. Fail if not.
+	 */
+	if (sc->sc_class == NULL)
+		return (ENXIO);
+
 	/*
 	 * Initialize the instance. Note that the instance (=softc) does
 	 * not necessarily match the hardware specific softc. We can't do
@@ -300,11 +327,10 @@ uart_bus_probe(device_t dev, int regshft, int rclk, int rid, int chan)
 	 * 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);
+		device_set_desc(dev, uart_getname(sc->sc_class));
 
 	/*
 	 * Allocate the register resource. We assume that all UARTs have
@@ -316,12 +342,13 @@ uart_bus_probe(device_t dev, int regshft, int rclk, int rid, int chan)
 	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);
+	    0, ~0, uart_getrange(sc->sc_class), 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);
+		    &sc->sc_rrid, 0, ~0, uart_getrange(sc->sc_class),
+		    RF_ACTIVE);
 		if (sc->sc_rres == NULL)
 			return (ENXIO);
 	}
@@ -390,7 +417,7 @@ uart_bus_attach(device_t dev)
 	 * 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);
+	    0, ~0, uart_getrange(sc->sc_class), RF_ACTIVE);
 	if (sc->sc_rres == NULL) {
 		mtx_destroy(&sc->sc_hwmtx_s);
 		return (ENXIO);
diff --git a/sys/dev/uart/uart_cpu.h b/sys/dev/uart/uart_cpu.h
index b41ed508f09ef..db64d497e5946 100644
--- a/sys/dev/uart/uart_cpu.h
+++ b/sys/dev/uart/uart_cpu.h
@@ -45,11 +45,6 @@ struct uart_ops {
 	int (*getc)(struct uart_bas *, struct mtx *);
 };
 
-extern struct uart_ops uart_i8251_ops;
-extern struct uart_ops uart_ns8250_ops;
-extern struct uart_ops uart_sab82532_ops;
-extern struct uart_ops uart_z8530_ops;
-
 extern bus_space_tag_t uart_bus_space_io;
 extern bus_space_tag_t uart_bus_space_mem;
 
@@ -59,7 +54,7 @@ extern bus_space_tag_t uart_bus_space_mem;
 struct uart_softc;
 struct uart_devinfo {
 	SLIST_ENTRY(uart_devinfo) next;
-	struct uart_ops ops;
+	struct uart_ops *ops;
 	struct uart_bas bas;
 	int	baudrate;
 	int	databits;
@@ -77,7 +72,11 @@ struct uart_devinfo {
 
 int uart_cpu_eqres(struct uart_bas *, struct uart_bas *);
 int uart_cpu_getdev(int, struct uart_devinfo *);
-int uart_getenv(int, struct uart_devinfo *);
+
+int uart_getenv(int, struct uart_devinfo *, struct uart_class *);
+const char *uart_getname(struct uart_class *);
+struct uart_ops *uart_getops(struct uart_class *);
+int uart_getrange(struct uart_class *);
 
 void uart_add_sysdev(struct uart_devinfo *);
 
@@ -106,7 +105,7 @@ uart_probe(struct uart_devinfo *di)
 	int res;
 
 	uart_lock(di->hwmtx);
-	res = di->ops.probe(&di->bas);
+	res = di->ops->probe(&di->bas);
 	uart_unlock(di->hwmtx);
 	return (res);
 }
@@ -115,7 +114,7 @@ static __inline void
 uart_init(struct uart_devinfo *di)
 {
 	uart_lock(di->hwmtx);
-	di->ops.init(&di->bas, di->baudrate, di->databits, di->stopbits,
+	di->ops->init(&di->bas, di->baudrate, di->databits, di->stopbits,
 	    di->parity);
 	uart_unlock(di->hwmtx);
 }
@@ -124,7 +123,7 @@ static __inline void
 uart_term(struct uart_devinfo *di)
 {
 	uart_lock(di->hwmtx);
-	di->ops.term(&di->bas);
+	di->ops->term(&di->bas);
 	uart_unlock(di->hwmtx);
 }
 
@@ -132,7 +131,7 @@ static __inline void
 uart_putc(struct uart_devinfo *di, int c)
 {
 	uart_lock(di->hwmtx);
-	di->ops.putc(&di->bas, c);
+	di->ops->putc(&di->bas, c);
 	uart_unlock(di->hwmtx);
 }
 
@@ -142,7 +141,7 @@ uart_rxready(struct uart_devinfo *di)
 	int res;
 
 	uart_lock(di->hwmtx);
-	res = di->ops.rxready(&di->bas);
+	res = di->ops->rxready(&di->bas);
 	uart_unlock(di->hwmtx);
 	return (res);
 }
@@ -153,8 +152,8 @@ uart_poll(struct uart_devinfo *di)
 	int res;
 
 	uart_lock(di->hwmtx);
-	if (di->ops.rxready(&di->bas))
-		res = di->ops.getc(&di->bas, NULL);
+	if (di->ops->rxready(&di->bas))
+		res = di->ops->getc(&di->bas, NULL);
 	else
 		res = -1;
 	uart_unlock(di->hwmtx);
@@ -165,7 +164,7 @@ static __inline int
 uart_getc(struct uart_devinfo *di)
 {
 
-	return (di->ops.getc(&di->bas, di->hwmtx));
+	return (di->ops->getc(&di->bas, di->hwmtx));
 }
 
 #endif /* _DEV_UART_CPU_H_ */
diff --git a/sys/dev/uart/uart_cpu_amd64.c b/sys/dev/uart/uart_cpu_amd64.c
index fb8b99476eb60..3624f7973d5c4 100644
--- a/sys/dev/uart/uart_cpu_amd64.c
+++ b/sys/dev/uart/uart_cpu_amd64.c
@@ -49,11 +49,15 @@ uart_cpu_eqres(struct uart_bas *b1, struct uart_bas *b2)
 int
 uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
+	struct uart_class *class;
 	unsigned int i, ivar;
 
+	class = &uart_ns8250_class;
+	if (class == NULL)
+		return (ENXIO);
+
 	/* Check the environment. */
-	di->ops = uart_ns8250_ops;
-	if (uart_getenv(devtype, di) == 0)
+	if (uart_getenv(devtype, di, class) == 0)
 		return (0);
 
 	/*
@@ -82,10 +86,11 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 		 * Got it. Fill in the instance and return it. We only have
 		 * ns8250 and successors on i386.
 		 */
-		di->ops = uart_ns8250_ops;
+		di->ops = uart_getops(class);
 		di->bas.chan = 0;
 		di->bas.bst = uart_bus_space_io;
-		if (bus_space_map(di->bas.bst, ivar, 8, 0, &di->bas.bsh) != 0)
+		if (bus_space_map(di->bas.bst, ivar, uart_getrange(class), 0,
+		    &di->bas.bsh) != 0)
 			continue;
 		di->bas.regshft = 0;
 		di->bas.rclk = 0;
diff --git a/sys/dev/uart/uart_cpu_i386.c b/sys/dev/uart/uart_cpu_i386.c
index c8e2e2ec721fc..0d0f0f71134fa 100644
--- a/sys/dev/uart/uart_cpu_i386.c
+++ b/sys/dev/uart/uart_cpu_i386.c
@@ -49,11 +49,15 @@ uart_cpu_eqres(struct uart_bas *b1, struct uart_bas *b2)
 int
 uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
+	struct uart_class *class;
 	unsigned int i, ivar;
 
+	class = &uart_ns8250_class;
+	if (class == NULL)
+		return (ENXIO);
+
 	/* Check the environment. */
-	di->ops = uart_ns8250_ops;
-	if (uart_getenv(devtype, di) == 0)
+	if (uart_getenv(devtype, di, class) == 0)
 		return (0);
 
 	/*
@@ -82,10 +86,11 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 		 * Got it. Fill in the instance and return it. We only have
 		 * ns8250 and successors on i386.
 		 */
-		di->ops = uart_ns8250_ops;
+		di->ops = uart_getops(class);
 		di->bas.chan = 0;
 		di->bas.bst = uart_bus_space_io;
-		if (bus_space_map(di->bas.bst, ivar, 8, 0, &di->bas.bsh) != 0)
+		if (bus_space_map(di->bas.bst, ivar, uart_getrange(class), 0,
+		    &di->bas.bsh) != 0)
 			continue;
 		di->bas.regshft = 0;
 		di->bas.rclk = 0;
diff --git a/sys/dev/uart/uart_cpu_ia64.c b/sys/dev/uart/uart_cpu_ia64.c
index 496049200c2d4..9a71e20e506e0 100644
--- a/sys/dev/uart/uart_cpu_ia64.c
+++ b/sys/dev/uart/uart_cpu_ia64.c
@@ -59,10 +59,15 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
 	struct dig64_hcdp_table *tbl;
 	struct dig64_hcdp_entry *ent;
+	struct uart_class *class;
 	bus_addr_t addr;
 	uint64_t hcdp;
 	unsigned int i;
 
+	class = &uart_ns8250_class;
+	if (class == NULL)
+		return (ENXIO);
+
 	/*
 	 * Use the DIG64 HCDP table if present.
 	 */
@@ -82,12 +87,12 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 
 			addr = ent->address.addr_high;
 			addr = (addr << 32) + ent->address.addr_low;
-			di->ops = uart_ns8250_ops;
+			di->ops = uart_getops(class);
 			di->bas.chan = 0;
 			di->bas.bst = (ent->address.addr_space == 0)
 			    ? uart_bus_space_mem : uart_bus_space_io;
-			if (bus_space_map(di->bas.bst, addr, 8, 0,
-			    &di->bas.bsh) != 0)
+			if (bus_space_map(di->bas.bst, addr,
+			    uart_getrange(class), 0, &di->bas.bsh) != 0)
 				continue;
 			di->bas.regshft = 0;
 			di->bas.rclk = ent->pclock << 4;
@@ -104,6 +109,5 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 	}
 
 	/* Check the environment. */
-	di->ops = uart_ns8250_ops;
-	return (uart_getenv(devtype, di));
+	return (uart_getenv(devtype, di, class));
 }
diff --git a/sys/dev/uart/uart_cpu_pc98.c b/sys/dev/uart/uart_cpu_pc98.c
index 0887a67666241..c0c1f4e1d5c23 100644
--- a/sys/dev/uart/uart_cpu_pc98.c
+++ b/sys/dev/uart/uart_cpu_pc98.c
@@ -49,11 +49,15 @@ uart_cpu_eqres(struct uart_bas *b1, struct uart_bas *b2)
 int
 uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
+	struct uart_class *class;
 	unsigned int i, ivar, flags;
 
+	class = &uart_ns8250_class;
+	if (class == NULL)
+		return (ENXIO);
+
 	/* Check the environment. */
-	di->ops = uart_ns8250_ops;
-	if (uart_getenv(devtype, di) == 0)
+	if (uart_getenv(devtype, di, class) == 0)
 		return (0);
 
 	/*
@@ -81,10 +85,11 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 		    ivar == 0)
 			continue;
 
-		di->ops = uart_ns8250_ops;
+		di->ops = uart_getops(class);
 		di->bas.chan = 0;
 		di->bas.bst = uart_bus_space_io;
-		if (bus_space_map(di->bas.bst, ivar, 8, 0, &di->bas.bsh) != 0)
+		if (bus_space_map(di->bas.bst, ivar, uart_getrange(class), 0,
+		    &di->bas.bsh) != 0)
 			continue;
 		di->bas.regshft = 0;
 		di->bas.rclk = 0;
diff --git a/sys/dev/uart/uart_cpu_powerpc.c b/sys/dev/uart/uart_cpu_powerpc.c
index 53f57dc7e49a5..6647c7dbb3479 100644
--- a/sys/dev/uart/uart_cpu_powerpc.c
+++ b/sys/dev/uart/uart_cpu_powerpc.c
@@ -52,9 +52,14 @@ int
 uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
 	char buf[64];
+	struct uart_class *class;
 	phandle_t input, opts;
 	int error;
 
+	class = &uart_z8530_class;
+	if (class == NULL)
+		return (ENXIO);
+
 	if ((opts = OF_finddevice("/options")) == -1)
 		return (ENXIO);
 	switch (devtype) {
@@ -93,7 +98,7 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 	if (error)
 		return (error);
 
-	di->ops = uart_z8530_ops;
+	di->ops = uart_getops(class);
 
 	di->bas.rclk = 230400;
 	di->bas.chan = 1;
diff --git a/sys/dev/uart/uart_cpu_sparc64.c b/sys/dev/uart/uart_cpu_sparc64.c
index efe0283df2048..9d92a3908732f 100644
--- a/sys/dev/uart/uart_cpu_sparc64.c
+++ b/sys/dev/uart/uart_cpu_sparc64.c
@@ -194,9 +194,10 @@ int
 uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 {
 	char buf[32], compat[32], dev[64];
+	struct uart_class *class;
 	phandle_t input, options;
 	bus_addr_t addr;
-	int baud, bits, error, space, stop;
+	int baud, bits, error, range, space, stop;
 	char flag, par;
 
 	if ((options = OF_finddevice("/options")) == -1)
@@ -228,14 +229,15 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 		compat[0] = '\0';
 	di->bas.regshft = 0;
 	di->bas.rclk = 0;
+	class = NULL;
 	if (!strcmp(buf, "se") || !strcmp(compat, "sab82532")) {
-		di->ops = uart_sab82532_ops;
+		class = &uart_sab82532_class;
 		/* SAB82532 are only known to be used for TTYs. */
 		if ((di->bas.chan = uart_cpu_channel(dev)) == 0)
 			return (ENXIO);
-		addr += 64 * (di->bas.chan - 1);
+		addr += uart_getrange(class) * (di->bas.chan - 1);
 	} else if (!strcmp(buf, "zs")) {
-		di->ops = uart_z8530_ops;
+		class = &uart_z8530_class;
 		if ((di->bas.chan = uart_cpu_channel(dev)) == 0) {
 			/*
 			 * There's no way to determine from OF which
@@ -248,16 +250,19 @@ uart_cpu_getdev(int devtype, struct uart_devinfo *di)
 				return (ENXIO);
 		}
 		di->bas.regshft = 1;
-		addr += 4 - 4 * (di->bas.chan - 1);
+		range = uart_getrange(class) << di->bas.regshft;
+		addr += range - range * (di->bas.chan - 1);
 	} else if (!strcmp(buf, "lom-console") || !strcmp(buf, "su") ||
 	    !strcmp(buf, "su_pnp") || !strcmp(compat, "rsc-console") ||
 	    !strcmp(compat, "su") || !strcmp(compat, "su16550")) {
-		di->ops = uart_ns8250_ops;
+		class = &uart_ns8250_class;
 		di->bas.chan = 0;
-	} else
+	}
+	if (class == NULL)
 		return (ENXIO);
 
 	/* Fill in the device info. */
+	di->ops = uart_getops(class);
 	di->bas.bst = &bst_store[devtype];
 	di->bas.bsh = sparc64_fake_bustag(space, addr, di->bas.bst);
 
diff --git a/sys/dev/uart/uart_dev_ns8250.c b/sys/dev/uart/uart_dev_ns8250.c
index 8e6177be329d9..4e5141796d203 100644
--- a/sys/dev/uart/uart_dev_ns8250.c
+++ b/sys/dev/uart/uart_dev_ns8250.c
@@ -222,7 +222,7 @@ static void ns8250_putc(struct uart_bas *bas, int);
 static int ns8250_rxready(struct uart_bas *bas);
 static int ns8250_getc(struct uart_bas *bas, struct mtx *);
 
-struct uart_ops uart_ns8250_ops = {
+static struct uart_ops uart_ns8250_ops = {
 	.probe = ns8250_probe,
 	.init = ns8250_init,
 	.term = ns8250_term,
@@ -368,9 +368,10 @@ static kobj_method_t ns8250_methods[] = {
 };
 
 struct uart_class uart_ns8250_class = {
-	"ns8250 class",
+	"ns8250",
 	ns8250_methods,
 	sizeof(struct ns8250_softc),
+	.uc_ops = &uart_ns8250_ops,
 	.uc_range = 8,
 	.uc_rclk = DEFAULT_RCLK
 };
diff --git a/sys/dev/uart/uart_dev_sab82532.c b/sys/dev/uart/uart_dev_sab82532.c
index e10ae177a2774..11cdb4b47387a 100644
--- a/sys/dev/uart/uart_dev_sab82532.c
+++ b/sys/dev/uart/uart_dev_sab82532.c
@@ -176,7 +176,7 @@ static void sab82532_putc(struct uart_bas *bas, int);
 static int sab82532_rxready(struct uart_bas *bas);
 static int sab82532_getc(struct uart_bas *bas, struct mtx *);
 
-struct uart_ops uart_sab82532_ops = {
+static struct uart_ops uart_sab82532_ops = {
 	.probe = sab82532_probe,
 	.init = sab82532_init,
 	.term = sab82532_term,
@@ -382,9 +382,10 @@ static kobj_method_t sab82532_methods[] = {
 };
 
 struct uart_class uart_sab82532_class = {
-	"sab82532 class",
+	"sab82532",
 	sab82532_methods,
 	sizeof(struct sab82532_softc),
+	.uc_ops = &uart_sab82532_ops,
 	.uc_range = 64,
 	.uc_rclk = DEFAULT_RCLK
 };
diff --git a/sys/dev/uart/uart_dev_z8530.c b/sys/dev/uart/uart_dev_z8530.c
index 850971817050b..33bacdc98f72c 100644
--- a/sys/dev/uart/uart_dev_z8530.c
+++ b/sys/dev/uart/uart_dev_z8530.c
@@ -195,7 +195,7 @@ static void z8530_putc(struct uart_bas *bas, int);
 static int z8530_rxready(struct uart_bas *bas);
 static int z8530_getc(struct uart_bas *bas, struct mtx *);
 
-struct uart_ops uart_z8530_ops = {
+static struct uart_ops uart_z8530_ops = {
 	.probe = z8530_probe,
 	.init = z8530_init,
 	.term = z8530_term,
@@ -298,9 +298,10 @@ static kobj_method_t z8530_methods[] = {
 };
 
 struct uart_class uart_z8530_class = {
-	"z8530 class",
+	"z8530",
 	z8530_methods,
 	sizeof(struct z8530_softc),
+	.uc_ops = &uart_z8530_ops,
 	.uc_range = 2,
 	.uc_rclk = DEFAULT_RCLK
 };
diff --git a/sys/dev/uart/uart_kbd_sun.c b/sys/dev/uart/uart_kbd_sun.c
index 7395f9dcc12a1..78238a73d95c6 100644
--- a/sys/dev/uart/uart_kbd_sun.c
+++ b/sys/dev/uart/uart_kbd_sun.c
@@ -712,8 +712,8 @@ sunkbd_ioctl(keyboard_t *kbd, u_long cmd, caddr_t data)
 		if (*(int *)data & SLKED)
 			c |= SKBD_LED_SCROLLLOCK;
 		uart_lock(sc->sc_sysdev->hwmtx);
-		sc->sc_sysdev->ops.putc(&sc->sc_sysdev->bas, SKBD_CMD_SETLED);
-		sc->sc_sysdev->ops.putc(&sc->sc_sysdev->bas, c);
+		sc->sc_sysdev->ops->putc(&sc->sc_sysdev->bas, SKBD_CMD_SETLED);
+		sc->sc_sysdev->ops->putc(&sc->sc_sysdev->bas, c);
 		uart_unlock(sc->sc_sysdev->hwmtx);
 		KBD_LED_VAL(kbd) = *(int *)data;
 		break;
diff --git a/sys/dev/uart/uart_subr.c b/sys/dev/uart/uart_subr.c
index c9b6fe7ab5042..2cab82535d0a7 100644
--- a/sys/dev/uart/uart_subr.c
+++ b/sys/dev/uart/uart_subr.c
@@ -48,12 +48,41 @@ __FBSDID("$FreeBSD$");
 #define	UART_TAG_SB	8
 #define	UART_TAG_XO	9
 
+static struct uart_class *uart_classes[] = {
+	&uart_ns8250_class,
+	&uart_sab82532_class,
+	&uart_z8530_class,
+};
+static size_t uart_nclasses = sizeof(uart_classes) / sizeof(uart_classes[0]);
+
 static bus_addr_t
 uart_parse_addr(__const char **p)
 {
 	return (strtoul(*p, (char**)(uintptr_t)p, 0));
 }
 
+static struct uart_class *
+uart_parse_class(struct uart_class *class, __const char **p)
+{
+	struct uart_class *uc;
+	const char *nm;
+	size_t len;
+	u_int i;
+
+	for (i = 0; i < uart_nclasses; i++) {
+		uc = uart_classes[i];
+		nm = uart_getname(uc);
+		if (nm == NULL || *nm == '\0')
+			continue;
+		len = strlen(nm);
+		if (strncmp(nm, *p, len) == 0) {
+			*p += len;
+			return (uc);
+		}
+	}
+	return (class);
+}
+
 static long
 uart_parse_long(__const char **p)
 {
@@ -161,10 +190,18 @@ out:
  */
 
 int
-uart_getenv(int devtype, struct uart_devinfo *di)
+uart_getenv(int devtype, struct uart_devinfo *di, struct uart_class *class)
 {
 	__const char *spec;
 	bus_addr_t addr = ~0U;
+	int error;
+
+	/*
+	 * All uart_class references are weak. Make sure the default
+	 * device class has been compiled-in.
+	 */
+	if (class == NULL)
+		return (ENXIO);
 
 	/*
 	 * Check the environment variables "hw.uart.console" and
@@ -203,7 +240,7 @@ uart_getenv(int devtype, struct uart_devinfo *di)
 			di->databits = uart_parse_long(&spec);
 			break;
 		case UART_TAG_DT:
-			return (EINVAL);	/* XXX not yet implemented. */
+			class = uart_parse_class(class, &spec);
 			break;
 		case UART_TAG_IO:
 			di->bas.bst = uart_bus_space_io;
@@ -261,8 +298,9 @@ uart_getenv(int devtype, struct uart_devinfo *di)
 	} else
 		di->baudrate = 0;
 
-	/* XXX the size of the mapping depends on the UART class. */
-	if (bus_space_map(di->bas.bst, addr, 8, 0, &di->bas.bsh) != 0)
-		return (EINVAL);
-	return (0);
+	/* Set the ops and create a bus space handle. */
+	di->ops = uart_getops(class);
+	error = bus_space_map(di->bas.bst, addr, uart_getrange(class), 0,
+	    &di->bas.bsh);
+	return (error);
 }