xref: /freebsd/sys/arm/xilinx/uart_dev_cdnc.c (revision e0c4386e)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2005 Olivier Houchard All rights reserved.
5  * Copyright (c) 2012 Thomas Skibo All rights reserved.
6  * Copyright (c) 2005 M. Warner Losh <imp@FreeBSD.org>
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  */
30 
31 /* A driver for the Cadence AMBA UART as used by the Xilinx Zynq-7000.
32  *
33  * Reference: Zynq-7000 All Programmable SoC Technical Reference Manual.
34  * (v1.4) November 16, 2012.  Xilinx doc UG585.  UART is covered in Ch. 19
35  * and register definitions are in appendix B.33.
36  */
37 
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/bus.h>
41 #include <sys/conf.h>
42 #include <sys/cons.h>
43 #include <machine/bus.h>
44 
45 #include <dev/uart/uart.h>
46 #include <dev/uart/uart_cpu.h>
47 #include <dev/uart/uart_cpu_fdt.h>
48 #include <dev/uart/uart_bus.h>
49 
50 #include "uart_if.h"
51 
52 #define	UART_FIFO_SIZE	64
53 
54 #define	RD4(bas, reg)		\
55 	bus_space_read_4((bas)->bst, (bas)->bsh, uart_regofs((bas), (reg)))
56 #define	WR4(bas, reg, value)	\
57 	bus_space_write_4((bas)->bst, (bas)->bsh, uart_regofs((bas), (reg)), \
58 			  (value))
59 
60 /* Register definitions for Cadence UART Controller.
61  */
62 #define CDNC_UART_CTRL_REG	0x00		/* Control Register. */
63 #define CDNC_UART_CTRL_REG_STOPBRK	(1<<8)
64 #define CDNC_UART_CTRL_REG_STARTBRK	(1<<7)
65 #define CDNC_UART_CTRL_REG_TORST	(1<<6)
66 #define CDNC_UART_CTRL_REG_TX_DIS	(1<<5)
67 #define CDNC_UART_CTRL_REG_TX_EN	(1<<4)
68 #define CDNC_UART_CTRL_REG_RX_DIS	(1<<3)
69 #define CDNC_UART_CTRL_REG_RX_EN	(1<<2)
70 #define CDNC_UART_CTRL_REG_TXRST	(1<<1)
71 #define CDNC_UART_CTRL_REG_RXRST	(1<<0)
72 
73 #define CDNC_UART_MODE_REG	0x04		/* Mode Register. */
74 #define CDNC_UART_MODE_REG_CHMOD_R_LOOP	(3<<8)	/* [9:8] - channel mode */
75 #define CDNC_UART_MODE_REG_CHMOD_L_LOOP	(2<<8)
76 #define CDNC_UART_MODE_REG_CHMOD_AUTECHO (1<<8)
77 #define CDNC_UART_MODE_REG_STOP2	(2<<6)	/* [7:6] - stop bits */
78 #define CDNC_UART_MODE_REG_PAR_NONE	(4<<3)	/* [5:3] - parity type */
79 #define CDNC_UART_MODE_REG_PAR_MARK	(3<<3)
80 #define CDNC_UART_MODE_REG_PAR_SPACE	(2<<3)
81 #define CDNC_UART_MODE_REG_PAR_ODD	(1<<3)
82 #define CDNC_UART_MODE_REG_PAR_EVEN	(0<<3)
83 #define CDNC_UART_MODE_REG_6BIT		(3<<1)	/* [2:1] - character len */
84 #define CDNC_UART_MODE_REG_7BIT		(2<<1)
85 #define CDNC_UART_MODE_REG_8BIT		(0<<1)
86 #define CDNC_UART_MODE_REG_CLKSEL	(1<<0)
87 
88 #define CDNC_UART_IEN_REG	0x08		/* Interrupt registers. */
89 #define CDNC_UART_IDIS_REG	0x0C
90 #define CDNC_UART_IMASK_REG	0x10
91 #define CDNC_UART_ISTAT_REG	0x14
92 #define CDNC_UART_INT_TXOVR		(1<<12)
93 #define CDNC_UART_INT_TXNRLYFUL		(1<<11)	/* tx "nearly" full */
94 #define CDNC_UART_INT_TXTRIG		(1<<10)
95 #define CDNC_UART_INT_DMSI		(1<<9)	/* delta modem status */
96 #define CDNC_UART_INT_RXTMOUT		(1<<8)
97 #define CDNC_UART_INT_PARITY		(1<<7)
98 #define CDNC_UART_INT_FRAMING		(1<<6)
99 #define CDNC_UART_INT_RXOVR		(1<<5)
100 #define CDNC_UART_INT_TXFULL		(1<<4)
101 #define CDNC_UART_INT_TXEMPTY		(1<<3)
102 #define CDNC_UART_INT_RXFULL		(1<<2)
103 #define CDNC_UART_INT_RXEMPTY		(1<<1)
104 #define CDNC_UART_INT_RXTRIG		(1<<0)
105 #define CDNC_UART_INT_ALL		0x1FFF
106 
107 #define CDNC_UART_BAUDGEN_REG	0x18
108 #define CDNC_UART_RX_TIMEO_REG	0x1C
109 #define CDNC_UART_RX_WATER_REG	0x20
110 
111 #define CDNC_UART_MODEM_CTRL_REG 0x24
112 #define CDNC_UART_MODEM_CTRL_REG_FCM	(1<<5)	/* automatic flow control */
113 #define CDNC_UART_MODEM_CTRL_REG_RTS	(1<<1)
114 #define CDNC_UART_MODEM_CTRL_REG_DTR	(1<<0)
115 
116 #define CDNC_UART_MODEM_STAT_REG 0x28
117 #define CDNC_UART_MODEM_STAT_REG_FCMS	(1<<8)	/* flow control mode (rw) */
118 #define CDNC_UART_MODEM_STAT_REG_DCD	(1<<7)
119 #define CDNC_UART_MODEM_STAT_REG_RI	(1<<6)
120 #define CDNC_UART_MODEM_STAT_REG_DSR	(1<<5)
121 #define CDNC_UART_MODEM_STAT_REG_CTS	(1<<4)
122 #define CDNC_UART_MODEM_STAT_REG_DDCD	(1<<3)	/* change in DCD (w1tc) */
123 #define CDNC_UART_MODEM_STAT_REG_TERI	(1<<2)	/* trail edge ring (w1tc) */
124 #define CDNC_UART_MODEM_STAT_REG_DDSR	(1<<1)	/* change in DSR (w1tc) */
125 #define CDNC_UART_MODEM_STAT_REG_DCTS	(1<<0)	/* change in CTS (w1tc) */
126 
127 #define CDNC_UART_CHAN_STAT_REG	0x2C		/* Channel status register. */
128 #define CDNC_UART_CHAN_STAT_REG_TXNRLYFUL (1<<14) /* tx "nearly" full */
129 #define CDNC_UART_CHAN_STAT_REG_TXTRIG	(1<<13)
130 #define CDNC_UART_CHAN_STAT_REG_FDELT	(1<<12)
131 #define CDNC_UART_CHAN_STAT_REG_TXACTIVE (1<<11)
132 #define CDNC_UART_CHAN_STAT_REG_RXACTIVE (1<<10)
133 #define CDNC_UART_CHAN_STAT_REG_TXFULL	(1<<4)
134 #define CDNC_UART_CHAN_STAT_REG_TXEMPTY	(1<<3)
135 #define CDNC_UART_CHAN_STAT_REG_RXEMPTY	(1<<1)
136 #define CDNC_UART_CHAN_STAT_REG_RXTRIG	(1<<0)
137 
138 #define CDNC_UART_FIFO		0x30		/* Data FIFO (tx and rx) */
139 #define CDNC_UART_BAUDDIV_REG	0x34
140 #define CDNC_UART_FLOWDEL_REG	0x38
141 #define CDNC_UART_TX_WATER_REG	0x44
142 
143 /*
144  * Low-level UART interface.
145  */
146 static int cdnc_uart_probe(struct uart_bas *bas);
147 static void cdnc_uart_init(struct uart_bas *bas, int, int, int, int);
148 static void cdnc_uart_term(struct uart_bas *bas);
149 static void cdnc_uart_putc(struct uart_bas *bas, int);
150 static int cdnc_uart_rxready(struct uart_bas *bas);
151 static int cdnc_uart_getc(struct uart_bas *bas, struct mtx *mtx);
152 
153 extern SLIST_HEAD(uart_devinfo_list, uart_devinfo) uart_sysdevs;
154 
155 static struct uart_ops cdnc_uart_ops = {
156 	.probe = cdnc_uart_probe,
157 	.init = cdnc_uart_init,
158 	.term = cdnc_uart_term,
159 	.putc = cdnc_uart_putc,
160 	.rxready = cdnc_uart_rxready,
161 	.getc = cdnc_uart_getc,
162 };
163 
164 #define	SIGCHG(c, i, s, d)				\
165 	if (c) {					\
166 		i |= (i & s) ? s : s | d;		\
167 	} else {					\
168 		i = (i & s) ? (i & ~s) | d : i;		\
169 	}
170 
171 static int
172 cdnc_uart_probe(struct uart_bas *bas)
173 {
174 
175 	return (0);
176 }
177 
178 static int
179 cdnc_uart_set_baud(struct uart_bas *bas, int baudrate)
180 {
181 	uint32_t baudgen, bauddiv;
182 	uint32_t best_bauddiv, best_baudgen, best_error;
183 	uint32_t baud_out, err;
184 
185 	best_bauddiv = 0;
186 	best_baudgen = 0;
187 	best_error = ~0;
188 
189 	/* Try all possible bauddiv values and pick best match. */
190 	for (bauddiv = 4; bauddiv <= 255; bauddiv++) {
191 		baudgen = (bas->rclk + (baudrate * (bauddiv + 1)) / 2) /
192 			(baudrate * (bauddiv + 1));
193 		if (baudgen < 1 || baudgen > 0xffff)
194 			continue;
195 
196 		baud_out = bas->rclk / (baudgen * (bauddiv + 1));
197 		err = baud_out > baudrate ?
198 			baud_out - baudrate : baudrate - baud_out;
199 
200 		if (err < best_error) {
201 			best_error = err;
202 			best_bauddiv = bauddiv;
203 			best_baudgen = baudgen;
204 		}
205 	}
206 
207 	if (best_bauddiv > 0) {
208 		WR4(bas, CDNC_UART_BAUDDIV_REG, best_bauddiv);
209 		WR4(bas, CDNC_UART_BAUDGEN_REG, best_baudgen);
210 		return (0);
211 	} else
212 		return (-1); /* out of range */
213 }
214 
215 static int
216 cdnc_uart_set_params(struct uart_bas *bas, int baudrate, int databits,
217 		      int stopbits, int parity)
218 {
219 	uint32_t mode_reg_value = 0;
220 
221 	switch (databits) {
222 	case 6:
223 		mode_reg_value |= CDNC_UART_MODE_REG_6BIT;
224 		break;
225 	case 7:
226 		mode_reg_value |= CDNC_UART_MODE_REG_7BIT;
227 		break;
228 	case 8:
229 	default:
230 		mode_reg_value |= CDNC_UART_MODE_REG_8BIT;
231 		break;
232 	}
233 
234 	if (stopbits == 2)
235 		mode_reg_value |= CDNC_UART_MODE_REG_STOP2;
236 
237 	switch (parity) {
238 	case UART_PARITY_MARK:
239 		mode_reg_value |= CDNC_UART_MODE_REG_PAR_MARK;
240 		break;
241 	case UART_PARITY_SPACE:
242 		mode_reg_value |= CDNC_UART_MODE_REG_PAR_SPACE;
243 		break;
244 	case UART_PARITY_ODD:
245 		mode_reg_value |= CDNC_UART_MODE_REG_PAR_ODD;
246 		break;
247 	case UART_PARITY_EVEN:
248 		mode_reg_value |= CDNC_UART_MODE_REG_PAR_EVEN;
249 		break;
250 	case UART_PARITY_NONE:
251 	default:
252 		mode_reg_value |= CDNC_UART_MODE_REG_PAR_NONE;
253 		break;
254 	}
255 
256 	WR4(bas, CDNC_UART_MODE_REG, mode_reg_value);
257 
258 	if (baudrate > 0 && cdnc_uart_set_baud(bas, baudrate) < 0)
259 		return (EINVAL);
260 
261 	return(0);
262 }
263 
264 static void
265 cdnc_uart_hw_init(struct uart_bas *bas)
266 {
267 
268 	/* Reset RX and TX. */
269 	WR4(bas, CDNC_UART_CTRL_REG,
270 	    CDNC_UART_CTRL_REG_RXRST | CDNC_UART_CTRL_REG_TXRST);
271 
272 	/* Interrupts all off. */
273 	WR4(bas, CDNC_UART_IDIS_REG, CDNC_UART_INT_ALL);
274 	WR4(bas, CDNC_UART_ISTAT_REG, CDNC_UART_INT_ALL);
275 
276 	/* Clear delta bits. */
277 	WR4(bas, CDNC_UART_MODEM_STAT_REG,
278 	    CDNC_UART_MODEM_STAT_REG_DDCD | CDNC_UART_MODEM_STAT_REG_TERI |
279 	    CDNC_UART_MODEM_STAT_REG_DDSR | CDNC_UART_MODEM_STAT_REG_DCTS);
280 
281 	/* RX FIFO water level, stale timeout */
282 	WR4(bas, CDNC_UART_RX_WATER_REG, UART_FIFO_SIZE/2);
283 	WR4(bas, CDNC_UART_RX_TIMEO_REG, 10);
284 
285 	/* TX FIFO water level (not used.) */
286 	WR4(bas, CDNC_UART_TX_WATER_REG, UART_FIFO_SIZE/2);
287 
288 	/* Bring RX and TX online. */
289 	WR4(bas, CDNC_UART_CTRL_REG,
290 	    CDNC_UART_CTRL_REG_RX_EN | CDNC_UART_CTRL_REG_TX_EN |
291 	    CDNC_UART_CTRL_REG_TORST | CDNC_UART_CTRL_REG_STOPBRK);
292 
293 	/* Set DTR and RTS. */
294 	WR4(bas, CDNC_UART_MODEM_CTRL_REG, CDNC_UART_MODEM_CTRL_REG_DTR |
295 	    CDNC_UART_MODEM_CTRL_REG_RTS);
296 }
297 
298 /*
299  * Initialize this device for use as a console.
300  */
301 static void
302 cdnc_uart_init(struct uart_bas *bas, int baudrate, int databits, int stopbits,
303 	      int parity)
304 {
305 
306 	/* Initialize hardware. */
307 	cdnc_uart_hw_init(bas);
308 
309 	/* Set baudrate, parameters. */
310 	(void)cdnc_uart_set_params(bas, baudrate, databits, stopbits, parity);
311 }
312 
313 /*
314  * Free resources now that we're no longer the console.  This appears to
315  * be never called, and I'm unsure quite what to do if I am called.
316  */
317 static void
318 cdnc_uart_term(struct uart_bas *bas)
319 {
320 
321 	/* XXX */
322 }
323 
324 /*
325  * Put a character of console output (so we do it here polling rather than
326  * interrupt driven).
327  */
328 static void
329 cdnc_uart_putc(struct uart_bas *bas, int c)
330 {
331 
332 	/* Wait for room. */
333 	while ((RD4(bas,CDNC_UART_CHAN_STAT_REG) &
334 		CDNC_UART_CHAN_STAT_REG_TXFULL) != 0)
335 		;
336 
337 	WR4(bas, CDNC_UART_FIFO, c);
338 
339 	while ((RD4(bas,CDNC_UART_CHAN_STAT_REG) &
340 		CDNC_UART_CHAN_STAT_REG_TXEMPTY) == 0)
341 		;
342 }
343 
344 /*
345  * Check for a character available.
346  */
347 static int
348 cdnc_uart_rxready(struct uart_bas *bas)
349 {
350 
351 	return ((RD4(bas, CDNC_UART_CHAN_STAT_REG) &
352 		 CDNC_UART_CHAN_STAT_REG_RXEMPTY) == 0);
353 }
354 
355 /*
356  * Block waiting for a character.
357  */
358 static int
359 cdnc_uart_getc(struct uart_bas *bas, struct mtx *mtx)
360 {
361 	int c;
362 
363 	uart_lock(mtx);
364 
365 	while ((RD4(bas, CDNC_UART_CHAN_STAT_REG) &
366 		CDNC_UART_CHAN_STAT_REG_RXEMPTY) != 0) {
367 		uart_unlock(mtx);
368 		DELAY(4);
369 		uart_lock(mtx);
370 	}
371 
372 	c = RD4(bas, CDNC_UART_FIFO);
373 
374 	uart_unlock(mtx);
375 
376 	c &= 0xff;
377 	return (c);
378 }
379 
380 /*****************************************************************************/
381 /*
382  * High-level UART interface.
383  */
384 
385 static int cdnc_uart_bus_probe(struct uart_softc *sc);
386 static int cdnc_uart_bus_attach(struct uart_softc *sc);
387 static int cdnc_uart_bus_flush(struct uart_softc *, int);
388 static int cdnc_uart_bus_getsig(struct uart_softc *);
389 static int cdnc_uart_bus_ioctl(struct uart_softc *, int, intptr_t);
390 static int cdnc_uart_bus_ipend(struct uart_softc *);
391 static int cdnc_uart_bus_param(struct uart_softc *, int, int, int, int);
392 static int cdnc_uart_bus_receive(struct uart_softc *);
393 static int cdnc_uart_bus_setsig(struct uart_softc *, int);
394 static int cdnc_uart_bus_transmit(struct uart_softc *);
395 static void cdnc_uart_bus_grab(struct uart_softc *);
396 static void cdnc_uart_bus_ungrab(struct uart_softc *);
397 
398 static kobj_method_t cdnc_uart_bus_methods[] = {
399 	KOBJMETHOD(uart_probe,		cdnc_uart_bus_probe),
400 	KOBJMETHOD(uart_attach, 	cdnc_uart_bus_attach),
401 	KOBJMETHOD(uart_flush,		cdnc_uart_bus_flush),
402 	KOBJMETHOD(uart_getsig,		cdnc_uart_bus_getsig),
403 	KOBJMETHOD(uart_ioctl,		cdnc_uart_bus_ioctl),
404 	KOBJMETHOD(uart_ipend,		cdnc_uart_bus_ipend),
405 	KOBJMETHOD(uart_param,		cdnc_uart_bus_param),
406 	KOBJMETHOD(uart_receive,	cdnc_uart_bus_receive),
407 	KOBJMETHOD(uart_setsig,		cdnc_uart_bus_setsig),
408 	KOBJMETHOD(uart_transmit,	cdnc_uart_bus_transmit),
409 	KOBJMETHOD(uart_grab,		cdnc_uart_bus_grab),
410 	KOBJMETHOD(uart_ungrab,		cdnc_uart_bus_ungrab),
411 
412 	KOBJMETHOD_END
413 };
414 
415 int
416 cdnc_uart_bus_probe(struct uart_softc *sc)
417 {
418 
419 	sc->sc_txfifosz = UART_FIFO_SIZE;
420 	sc->sc_rxfifosz = UART_FIFO_SIZE;
421 	sc->sc_hwiflow = 0;
422 	sc->sc_hwoflow = 0;
423 
424 	device_set_desc(sc->sc_dev, "Cadence UART");
425 
426 	return (0);
427 }
428 
429 static int
430 cdnc_uart_bus_attach(struct uart_softc *sc)
431 {
432 	struct uart_bas *bas = &sc->sc_bas;
433 	struct uart_devinfo *di;
434 
435 	if (sc->sc_sysdev != NULL) {
436 		di = sc->sc_sysdev;
437 		(void)cdnc_uart_set_params(bas, di->baudrate, di->databits,
438 					   di->stopbits, di->parity);
439 	} else
440 		cdnc_uart_hw_init(bas);
441 
442 	(void)cdnc_uart_bus_getsig(sc);
443 
444 	/* Enable interrupts. */
445 	WR4(bas, CDNC_UART_IEN_REG,
446 	    CDNC_UART_INT_RXTRIG | CDNC_UART_INT_RXTMOUT |
447 	    CDNC_UART_INT_TXOVR | CDNC_UART_INT_RXOVR |
448 	    CDNC_UART_INT_DMSI);
449 
450 	return (0);
451 }
452 
453 static int
454 cdnc_uart_bus_transmit(struct uart_softc *sc)
455 {
456 	int i;
457 	struct uart_bas *bas = &sc->sc_bas;
458 
459 	uart_lock(sc->sc_hwmtx);
460 
461 	/* Clear sticky TXEMPTY status bit. */
462 	WR4(bas, CDNC_UART_ISTAT_REG, CDNC_UART_INT_TXEMPTY);
463 
464 	for (i = 0; i < sc->sc_txdatasz; i++)
465 		WR4(bas, CDNC_UART_FIFO, sc->sc_txbuf[i]);
466 
467 	/* Enable TX empty interrupt. */
468 	WR4(bas, CDNC_UART_IEN_REG, CDNC_UART_INT_TXEMPTY);
469 	sc->sc_txbusy = 1;
470 
471 	uart_unlock(sc->sc_hwmtx);
472 
473 	return (0);
474 }
475 
476 static int
477 cdnc_uart_bus_setsig(struct uart_softc *sc, int sig)
478 {
479 	struct uart_bas *bas = &sc->sc_bas;
480 	uint32_t new, old, modem_ctrl;
481 
482 	do {
483 		old = sc->sc_hwsig;
484 		new = old;
485 		if (sig & SER_DDTR) {
486 			SIGCHG(sig & SER_DTR, new, SER_DTR, SER_DDTR);
487 		}
488 		if (sig & SER_DRTS) {
489 			SIGCHG(sig & SER_RTS, new, SER_RTS, SER_DRTS);
490 		}
491 	} while (!atomic_cmpset_32(&sc->sc_hwsig, old, new));
492 	uart_lock(sc->sc_hwmtx);
493 	modem_ctrl = RD4(bas, CDNC_UART_MODEM_CTRL_REG) &
494 		~(CDNC_UART_MODEM_CTRL_REG_DTR | CDNC_UART_MODEM_CTRL_REG_RTS);
495 	if ((new & SER_DTR) != 0)
496 		modem_ctrl |= CDNC_UART_MODEM_CTRL_REG_DTR;
497 	if ((new & SER_RTS) != 0)
498 		modem_ctrl |= CDNC_UART_MODEM_CTRL_REG_RTS;
499 	WR4(bas, CDNC_UART_MODEM_CTRL_REG, modem_ctrl);
500 
501 	uart_unlock(sc->sc_hwmtx);
502 	return (0);
503 }
504 
505 static int
506 cdnc_uart_bus_receive(struct uart_softc *sc)
507 {
508 	struct uart_bas *bas = &sc->sc_bas;
509 	uint32_t status;
510 	int c, c_status = 0;
511 
512 	uart_lock(sc->sc_hwmtx);
513 
514 	/* Check for parity or framing errors and clear the status bits. */
515 	status = RD4(bas, CDNC_UART_ISTAT_REG);
516 	if ((status & (CDNC_UART_INT_FRAMING | CDNC_UART_INT_PARITY)) != 0) {
517 		WR4(bas, CDNC_UART_ISTAT_REG,
518 		    status & (CDNC_UART_INT_FRAMING | CDNC_UART_INT_PARITY));
519 		if ((status & CDNC_UART_INT_PARITY) != 0)
520 			c_status |= UART_STAT_PARERR;
521 		if ((status & CDNC_UART_INT_FRAMING) != 0)
522 			c_status |= UART_STAT_FRAMERR;
523 	}
524 
525 	while ((RD4(bas, CDNC_UART_CHAN_STAT_REG) &
526 		CDNC_UART_CHAN_STAT_REG_RXEMPTY) == 0) {
527 		c = RD4(bas, CDNC_UART_FIFO) & 0xff;
528 #ifdef KDB
529 		/* Detect break and drop into debugger. */
530 		if (c == 0 && (c_status & UART_STAT_FRAMERR) != 0 &&
531 		    sc->sc_sysdev != NULL &&
532 		    sc->sc_sysdev->type == UART_DEV_CONSOLE) {
533 			kdb_break();
534 			WR4(bas, CDNC_UART_ISTAT_REG, CDNC_UART_INT_FRAMING);
535 		}
536 #endif
537 		uart_rx_put(sc, c | c_status);
538 	}
539 
540 	uart_unlock(sc->sc_hwmtx);
541 
542 	return (0);
543 }
544 
545 static int
546 cdnc_uart_bus_param(struct uart_softc *sc, int baudrate, int databits,
547 		   int stopbits, int parity)
548 {
549 
550 	return (cdnc_uart_set_params(&sc->sc_bas, baudrate,
551 				    databits, stopbits, parity));
552 }
553 
554 static int
555 cdnc_uart_bus_ipend(struct uart_softc *sc)
556 {
557 	int ipend = 0;
558 	struct uart_bas *bas = &sc->sc_bas;
559 	uint32_t istatus;
560 
561 	uart_lock(sc->sc_hwmtx);
562 
563 	istatus = RD4(bas, CDNC_UART_ISTAT_REG);
564 
565 	/* Clear interrupt bits. */
566 	WR4(bas, CDNC_UART_ISTAT_REG, istatus &
567 	    (CDNC_UART_INT_RXTRIG | CDNC_UART_INT_RXTMOUT |
568 	     CDNC_UART_INT_TXOVR | CDNC_UART_INT_RXOVR |
569 	     CDNC_UART_INT_TXEMPTY | CDNC_UART_INT_DMSI));
570 
571 	/* Receive data. */
572 	if ((istatus & (CDNC_UART_INT_RXTRIG | CDNC_UART_INT_RXTMOUT)) != 0)
573 		ipend |= SER_INT_RXREADY;
574 
575 	/* Transmit fifo empty. */
576 	if (sc->sc_txbusy && (istatus & CDNC_UART_INT_TXEMPTY) != 0) {
577 		/* disable txempty interrupt. */
578 		WR4(bas, CDNC_UART_IDIS_REG, CDNC_UART_INT_TXEMPTY);
579 		ipend |= SER_INT_TXIDLE;
580 	}
581 
582 	/* TX Overflow. */
583 	if ((istatus & CDNC_UART_INT_TXOVR) != 0)
584 		ipend |= SER_INT_OVERRUN;
585 
586 	/* RX Overflow. */
587 	if ((istatus & CDNC_UART_INT_RXOVR) != 0)
588 		ipend |= SER_INT_OVERRUN;
589 
590 	/* Modem signal change. */
591 	if ((istatus & CDNC_UART_INT_DMSI) != 0) {
592 		WR4(bas, CDNC_UART_MODEM_STAT_REG,
593 		    CDNC_UART_MODEM_STAT_REG_DDCD |
594 		    CDNC_UART_MODEM_STAT_REG_TERI |
595 		    CDNC_UART_MODEM_STAT_REG_DDSR |
596 		    CDNC_UART_MODEM_STAT_REG_DCTS);
597 		ipend |= SER_INT_SIGCHG;
598 	}
599 
600 	uart_unlock(sc->sc_hwmtx);
601 	return (ipend);
602 }
603 
604 static int
605 cdnc_uart_bus_flush(struct uart_softc *sc, int what)
606 {
607 
608 	return (0);
609 }
610 
611 static int
612 cdnc_uart_bus_getsig(struct uart_softc *sc)
613 {
614 	struct uart_bas *bas = &sc->sc_bas;
615 	uint32_t new, old, sig;
616 	uint8_t modem_status;
617 
618 	do {
619 		old = sc->sc_hwsig;
620 		sig = old;
621 		uart_lock(sc->sc_hwmtx);
622 		modem_status = RD4(bas, CDNC_UART_MODEM_STAT_REG);
623 		uart_unlock(sc->sc_hwmtx);
624 		SIGCHG(modem_status & CDNC_UART_MODEM_STAT_REG_DSR,
625 		       sig, SER_DSR, SER_DDSR);
626 		SIGCHG(modem_status & CDNC_UART_MODEM_STAT_REG_CTS,
627 		       sig, SER_CTS, SER_DCTS);
628 		SIGCHG(modem_status & CDNC_UART_MODEM_STAT_REG_DCD,
629 		       sig, SER_DCD, SER_DDCD);
630 		SIGCHG(modem_status & CDNC_UART_MODEM_STAT_REG_RI,
631 		       sig, SER_RI,  SER_DRI);
632 		new = sig & ~SER_MASK_DELTA;
633 	} while (!atomic_cmpset_32(&sc->sc_hwsig, old, new));
634 	return (sig);
635 }
636 
637 static int
638 cdnc_uart_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
639 {
640 	struct uart_bas *bas = &sc->sc_bas;
641 	uint32_t uart_ctrl, modem_ctrl;
642 	int error = 0;
643 
644 	uart_lock(sc->sc_hwmtx);
645 
646 	switch (request) {
647 	case UART_IOCTL_BREAK:
648 		uart_ctrl = RD4(bas, CDNC_UART_CTRL_REG);
649 		if (data) {
650 			uart_ctrl |= CDNC_UART_CTRL_REG_STARTBRK;
651 			uart_ctrl &= ~CDNC_UART_CTRL_REG_STOPBRK;
652 		} else {
653 			uart_ctrl |= CDNC_UART_CTRL_REG_STOPBRK;
654 			uart_ctrl &= ~CDNC_UART_CTRL_REG_STARTBRK;
655 		}
656 		WR4(bas, CDNC_UART_CTRL_REG, uart_ctrl);
657 		break;
658 	case UART_IOCTL_IFLOW:
659 		modem_ctrl = RD4(bas, CDNC_UART_MODEM_CTRL_REG);
660 		if (data)
661 			modem_ctrl |= CDNC_UART_MODEM_CTRL_REG_RTS;
662 		else
663 			modem_ctrl &= ~CDNC_UART_MODEM_CTRL_REG_RTS;
664 		WR4(bas, CDNC_UART_MODEM_CTRL_REG, modem_ctrl);
665 		break;
666 	default:
667 		error = EINVAL;
668 		break;
669 	}
670 
671 	uart_unlock(sc->sc_hwmtx);
672 
673 	return (error);
674 }
675 
676 static void
677 cdnc_uart_bus_grab(struct uart_softc *sc)
678 {
679 
680 	/* Enable interrupts. */
681 	WR4(&sc->sc_bas, CDNC_UART_IEN_REG,
682 	    CDNC_UART_INT_TXOVR | CDNC_UART_INT_RXOVR |
683 	    CDNC_UART_INT_DMSI);
684 }
685 
686 static void
687 cdnc_uart_bus_ungrab(struct uart_softc *sc)
688 {
689 
690 	/* Enable interrupts. */
691 	WR4(&sc->sc_bas, CDNC_UART_IEN_REG,
692 	    CDNC_UART_INT_RXTRIG | CDNC_UART_INT_RXTMOUT |
693 	    CDNC_UART_INT_TXOVR | CDNC_UART_INT_RXOVR |
694 	    CDNC_UART_INT_DMSI);
695 }
696 
697 static struct uart_class uart_cdnc_class = {
698 	"cdnc_uart",
699 	cdnc_uart_bus_methods,
700 	sizeof(struct uart_softc),
701 	.uc_ops = &cdnc_uart_ops,
702 	.uc_range = 8
703 };
704 
705 static struct ofw_compat_data compat_data[] = {
706 	{"cadence,uart",	(uintptr_t)&uart_cdnc_class},
707 	{"cdns,uart-r1p12",	(uintptr_t)&uart_cdnc_class},
708 	{"xlnx,xuartps",	(uintptr_t)&uart_cdnc_class},
709 	{NULL,			(uintptr_t)NULL},
710 };
711 UART_FDT_CLASS_AND_DEVICE(compat_data);
712