xref: /freebsd/sys/dev/uart/uart_dev_pl011.c (revision 59c8e88e72633afbc47a4ace0d2170d00d51f7dc)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2012 Semihalf.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include "opt_acpi.h"
30 #include "opt_platform.h"
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/kernel.h>
35 #include <sys/bus.h>
36 
37 #include <machine/bus.h>
38 #include <machine/machdep.h>
39 
40 #include <dev/uart/uart.h>
41 #include <dev/uart/uart_cpu.h>
42 #ifdef FDT
43 #include <dev/uart/uart_cpu_fdt.h>
44 #include <dev/ofw/ofw_bus.h>
45 #endif
46 #include <dev/uart/uart_bus.h>
47 #include "uart_if.h"
48 
49 #ifdef DEV_ACPI
50 #include <dev/uart/uart_cpu_acpi.h>
51 #include <contrib/dev/acpica/include/acpi.h>
52 #include <contrib/dev/acpica/include/accommon.h>
53 #include <contrib/dev/acpica/include/actables.h>
54 #endif
55 
56 #include <sys/kdb.h>
57 
58 #ifdef __aarch64__
59 #define	IS_FDT	(arm64_bus_method == ARM64_BUS_FDT)
60 #elif defined(FDT)
61 #define	IS_FDT	1
62 #else
63 #error Unsupported configuration
64 #endif
65 
66 /* PL011 UART registers and masks*/
67 #define	UART_DR		0x00		/* Data register */
68 #define	DR_FE		(1 << 8)	/* Framing error */
69 #define	DR_PE		(1 << 9)	/* Parity error */
70 #define	DR_BE		(1 << 10)	/* Break error */
71 #define	DR_OE		(1 << 11)	/* Overrun error */
72 
73 #define	UART_FR		0x06		/* Flag register */
74 #define	FR_RXFE		(1 << 4)	/* Receive FIFO/reg empty */
75 #define	FR_TXFF		(1 << 5)	/* Transmit FIFO/reg full */
76 #define	FR_RXFF		(1 << 6)	/* Receive FIFO/reg full */
77 #define	FR_TXFE		(1 << 7)	/* Transmit FIFO/reg empty */
78 
79 #define	UART_IBRD	0x09		/* Integer baud rate register */
80 #define	IBRD_BDIVINT	0xffff	/* Significant part of int. divisor value */
81 
82 #define	UART_FBRD	0x0a		/* Fractional baud rate register */
83 #define	FBRD_BDIVFRAC	0x3f	/* Significant part of frac. divisor value */
84 
85 #define	UART_LCR_H	0x0b		/* Line control register */
86 #define	LCR_H_WLEN8	(0x3 << 5)
87 #define	LCR_H_WLEN7	(0x2 << 5)
88 #define	LCR_H_WLEN6	(0x1 << 5)
89 #define	LCR_H_FEN	(1 << 4)	/* FIFO mode enable */
90 #define	LCR_H_STP2	(1 << 3)	/* 2 stop frames at the end */
91 #define	LCR_H_EPS	(1 << 2)	/* Even parity select */
92 #define	LCR_H_PEN	(1 << 1)	/* Parity enable */
93 
94 #define	UART_CR		0x0c		/* Control register */
95 #define	CR_RXE		(1 << 9)	/* Receive enable */
96 #define	CR_TXE		(1 << 8)	/* Transmit enable */
97 #define	CR_UARTEN	(1 << 0)	/* UART enable */
98 
99 #define	UART_IFLS	0x0d		/* FIFO level select register */
100 #define	IFLS_RX_SHIFT	3		/* RX level in bits [5:3] */
101 #define	IFLS_TX_SHIFT	0		/* TX level in bits [2:0] */
102 #define	IFLS_MASK	0x07		/* RX/TX level is 3 bits */
103 #define	IFLS_LVL_1_8th	0		/* Interrupt at 1/8 full */
104 #define	IFLS_LVL_2_8th	1		/* Interrupt at 1/4 full */
105 #define	IFLS_LVL_4_8th	2		/* Interrupt at 1/2 full */
106 #define	IFLS_LVL_6_8th	3		/* Interrupt at 3/4 full */
107 #define	IFLS_LVL_7_8th	4		/* Interrupt at 7/8 full */
108 
109 #define	UART_IMSC	0x0e		/* Interrupt mask set/clear register */
110 #define	IMSC_MASK_ALL	0x7ff		/* Mask all interrupts */
111 
112 #define	UART_RIS	0x0f		/* Raw interrupt status register */
113 #define	UART_RXREADY	(1 << 4)	/* RX buffer full */
114 #define	UART_TXEMPTY	(1 << 5)	/* TX buffer empty */
115 #define	RIS_RTIM	(1 << 6)	/* Receive timeout */
116 #define	RIS_FE		(1 << 7)	/* Framing error interrupt status */
117 #define	RIS_PE		(1 << 8)	/* Parity error interrupt status */
118 #define	RIS_BE		(1 << 9)	/* Break error interrupt status */
119 #define	RIS_OE		(1 << 10)	/* Overrun interrupt status */
120 
121 #define	UART_MIS	0x10		/* Masked interrupt status register */
122 #define	UART_ICR	0x11		/* Interrupt clear register */
123 
124 #define	UART_PIDREG_0	0x3f8		/* Peripheral ID register 0 */
125 #define	UART_PIDREG_1	0x3f9		/* Peripheral ID register 1 */
126 #define	UART_PIDREG_2	0x3fa		/* Peripheral ID register 2 */
127 #define	UART_PIDREG_3	0x3fb		/* Peripheral ID register 3 */
128 
129 /*
130  * The hardware FIFOs are 16 bytes each on rev 2 and earlier hardware, 32 bytes
131  * on rev 3 and later.  We configure them to interrupt when 3/4 full/empty.  For
132  * RX we set the size to the full hardware capacity so that the uart core
133  * allocates enough buffer space to hold a complete fifo full of incoming data.
134  * For TX, we need to limit the size to the capacity we know will be available
135  * when the interrupt occurs; uart_core will feed exactly that many bytes to
136  * uart_pl011_bus_transmit() which must consume them all.
137  */
138 #define	FIFO_RX_SIZE_R2	16
139 #define	FIFO_TX_SIZE_R2	12
140 #define	FIFO_RX_SIZE_R3	32
141 #define	FIFO_TX_SIZE_R3	24
142 #define	FIFO_IFLS_BITS	((IFLS_LVL_6_8th << IFLS_RX_SHIFT) | (IFLS_LVL_2_8th))
143 
144 /*
145  * FIXME: actual register size is SoC-dependent, we need to handle it
146  */
147 #define	__uart_getreg(bas, reg)		\
148 	bus_space_read_4((bas)->bst, (bas)->bsh, uart_regofs(bas, reg))
149 #define	__uart_setreg(bas, reg, value)	\
150 	bus_space_write_4((bas)->bst, (bas)->bsh, uart_regofs(bas, reg), value)
151 
152 /*
153  * Low-level UART interface.
154  */
155 static int uart_pl011_probe(struct uart_bas *bas);
156 static void uart_pl011_init(struct uart_bas *bas, int, int, int, int);
157 static void uart_pl011_term(struct uart_bas *bas);
158 static void uart_pl011_putc(struct uart_bas *bas, int);
159 static int uart_pl011_rxready(struct uart_bas *bas);
160 static int uart_pl011_getc(struct uart_bas *bas, struct mtx *);
161 
162 static struct uart_ops uart_pl011_ops = {
163 	.probe = uart_pl011_probe,
164 	.init = uart_pl011_init,
165 	.term = uart_pl011_term,
166 	.putc = uart_pl011_putc,
167 	.rxready = uart_pl011_rxready,
168 	.getc = uart_pl011_getc,
169 };
170 
171 static int
172 uart_pl011_probe(struct uart_bas *bas)
173 {
174 
175 	return (0);
176 }
177 
178 static void
179 uart_pl011_param(struct uart_bas *bas, int baudrate, int databits, int stopbits,
180     int parity)
181 {
182 	uint32_t ctrl, line;
183 	uint32_t baud;
184 
185 	/*
186 	 * Zero all settings to make sure
187 	 * UART is disabled and not configured
188 	 */
189 	ctrl = line = 0x0;
190 	__uart_setreg(bas, UART_CR, ctrl);
191 
192 	/* As we know UART is disabled we may setup the line */
193 	switch (databits) {
194 	case 7:
195 		line |= LCR_H_WLEN7;
196 		break;
197 	case 6:
198 		line |= LCR_H_WLEN6;
199 		break;
200 	case 8:
201 	default:
202 		line |= LCR_H_WLEN8;
203 		break;
204 	}
205 
206 	if (stopbits == 2)
207 		line |= LCR_H_STP2;
208 	else
209 		line &= ~LCR_H_STP2;
210 
211 	if (parity)
212 		line |= LCR_H_PEN;
213 	else
214 		line &= ~LCR_H_PEN;
215 	line |= LCR_H_FEN;
216 
217 	/* Configure the rest */
218 	ctrl |= (CR_RXE | CR_TXE | CR_UARTEN);
219 
220 	if (bas->rclk != 0 && baudrate != 0) {
221 		baud = bas->rclk * 4 / baudrate;
222 		__uart_setreg(bas, UART_IBRD, ((uint32_t)(baud >> 6)) & IBRD_BDIVINT);
223 		__uart_setreg(bas, UART_FBRD, (uint32_t)(baud & 0x3F) & FBRD_BDIVFRAC);
224 	}
225 
226 	/* Add config. to line before reenabling UART */
227 	__uart_setreg(bas, UART_LCR_H, (__uart_getreg(bas, UART_LCR_H) &
228 	    ~0xff) | line);
229 
230 	/* Set rx and tx fifo levels. */
231 	__uart_setreg(bas, UART_IFLS, FIFO_IFLS_BITS);
232 
233 	__uart_setreg(bas, UART_CR, ctrl);
234 }
235 
236 static void
237 uart_pl011_init(struct uart_bas *bas, int baudrate, int databits, int stopbits,
238     int parity)
239 {
240 	/* Mask all interrupts */
241 	__uart_setreg(bas, UART_IMSC, __uart_getreg(bas, UART_IMSC) &
242 	    ~IMSC_MASK_ALL);
243 
244 	uart_pl011_param(bas, baudrate, databits, stopbits, parity);
245 }
246 
247 static void
248 uart_pl011_term(struct uart_bas *bas)
249 {
250 }
251 
252 #if CHECK_EARLY_PRINTF(pl011)
253 static void
254 uart_pl011_early_putc(int c)
255 {
256 	volatile uint32_t *fr = (uint32_t *)(socdev_va + UART_FR * 4);
257 	volatile uint32_t *dr = (uint32_t *)(socdev_va + UART_DR * 4);
258 
259 	while ((*fr & FR_TXFF) != 0)
260 		;
261 	*dr = c & 0xff;
262 }
263 early_putc_t *early_putc = uart_pl011_early_putc;
264 #endif /* CHECK_EARLY_PRINTF */
265 
266 static void
267 uart_pl011_putc(struct uart_bas *bas, int c)
268 {
269 
270 	/* Wait when TX FIFO full. Push character otherwise. */
271 	while (__uart_getreg(bas, UART_FR) & FR_TXFF)
272 		;
273 	__uart_setreg(bas, UART_DR, c & 0xff);
274 }
275 
276 static int
277 uart_pl011_rxready(struct uart_bas *bas)
278 {
279 
280 	return !(__uart_getreg(bas, UART_FR) & FR_RXFE);
281 }
282 
283 static int
284 uart_pl011_getc(struct uart_bas *bas, struct mtx *hwmtx)
285 {
286 	int c;
287 
288 	while (!uart_pl011_rxready(bas))
289 		;
290 	c = __uart_getreg(bas, UART_DR) & 0xff;
291 
292 	return (c);
293 }
294 
295 /*
296  * High-level UART interface.
297  */
298 struct uart_pl011_softc {
299 	struct uart_softc	base;
300 	uint16_t		imsc; /* Interrupt mask */
301 };
302 
303 static int uart_pl011_bus_attach(struct uart_softc *);
304 static int uart_pl011_bus_detach(struct uart_softc *);
305 static int uart_pl011_bus_flush(struct uart_softc *, int);
306 static int uart_pl011_bus_getsig(struct uart_softc *);
307 static int uart_pl011_bus_ioctl(struct uart_softc *, int, intptr_t);
308 static int uart_pl011_bus_ipend(struct uart_softc *);
309 static int uart_pl011_bus_param(struct uart_softc *, int, int, int, int);
310 static int uart_pl011_bus_probe(struct uart_softc *);
311 static int uart_pl011_bus_receive(struct uart_softc *);
312 static int uart_pl011_bus_setsig(struct uart_softc *, int);
313 static int uart_pl011_bus_transmit(struct uart_softc *);
314 static void uart_pl011_bus_grab(struct uart_softc *);
315 static void uart_pl011_bus_ungrab(struct uart_softc *);
316 
317 static kobj_method_t uart_pl011_methods[] = {
318 	KOBJMETHOD(uart_attach,		uart_pl011_bus_attach),
319 	KOBJMETHOD(uart_detach,		uart_pl011_bus_detach),
320 	KOBJMETHOD(uart_flush,		uart_pl011_bus_flush),
321 	KOBJMETHOD(uart_getsig,		uart_pl011_bus_getsig),
322 	KOBJMETHOD(uart_ioctl,		uart_pl011_bus_ioctl),
323 	KOBJMETHOD(uart_ipend,		uart_pl011_bus_ipend),
324 	KOBJMETHOD(uart_param,		uart_pl011_bus_param),
325 	KOBJMETHOD(uart_probe,		uart_pl011_bus_probe),
326 	KOBJMETHOD(uart_receive,	uart_pl011_bus_receive),
327 	KOBJMETHOD(uart_setsig,		uart_pl011_bus_setsig),
328 	KOBJMETHOD(uart_transmit,	uart_pl011_bus_transmit),
329 	KOBJMETHOD(uart_grab,		uart_pl011_bus_grab),
330 	KOBJMETHOD(uart_ungrab,		uart_pl011_bus_ungrab),
331 	{ 0, 0 }
332 };
333 
334 static struct uart_class uart_pl011_class = {
335 	"pl011",
336 	uart_pl011_methods,
337 	sizeof(struct uart_pl011_softc),
338 	.uc_ops = &uart_pl011_ops,
339 	.uc_range = 0x48,
340 	.uc_rclk = 0,
341 	.uc_rshift = 2
342 };
343 UART_CLASS(uart_pl011_class);
344 
345 #ifdef FDT
346 static struct ofw_compat_data fdt_compat_data[] = {
347 	{"arm,pl011",		(uintptr_t)&uart_pl011_class},
348 	{NULL,			(uintptr_t)NULL},
349 };
350 UART_FDT_CLASS_AND_DEVICE(fdt_compat_data);
351 #endif
352 
353 #ifdef DEV_ACPI
354 static struct acpi_uart_compat_data acpi_compat_data[] = {
355 	{"ARMH0011", &uart_pl011_class, ACPI_DBG2_ARM_PL011, 2, 0, 0, UART_F_IGNORE_SPCR_REGSHFT, "uart pl011"},
356 	{"ARMHB000", &uart_pl011_class, ACPI_DBG2_ARM_SBSA_GENERIC, 2, 0, 0, UART_F_IGNORE_SPCR_REGSHFT, "uart pl011"},
357 	{"ARMHB000", &uart_pl011_class, ACPI_DBG2_ARM_SBSA_32BIT, 2, 0, 0, UART_F_IGNORE_SPCR_REGSHFT, "uart pl011"},
358 	{NULL, NULL, 0, 0, 0, 0, 0, NULL},
359 };
360 UART_ACPI_CLASS_AND_DEVICE(acpi_compat_data);
361 #endif
362 
363 static int
364 uart_pl011_bus_attach(struct uart_softc *sc)
365 {
366 	struct uart_pl011_softc *psc;
367 	struct uart_bas *bas;
368 
369 	psc = (struct uart_pl011_softc *)sc;
370 	bas = &sc->sc_bas;
371 
372 	/* Enable interrupts */
373 	psc->imsc = (UART_RXREADY | RIS_RTIM | UART_TXEMPTY);
374 	__uart_setreg(bas, UART_IMSC, psc->imsc);
375 
376 	/* Clear interrupts */
377 	__uart_setreg(bas, UART_ICR, IMSC_MASK_ALL);
378 
379 	return (0);
380 }
381 
382 static int
383 uart_pl011_bus_detach(struct uart_softc *sc)
384 {
385 
386 	return (0);
387 }
388 
389 static int
390 uart_pl011_bus_flush(struct uart_softc *sc, int what)
391 {
392 
393 	return (0);
394 }
395 
396 static int
397 uart_pl011_bus_getsig(struct uart_softc *sc)
398 {
399 
400 	return (0);
401 }
402 
403 static int
404 uart_pl011_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
405 {
406 	int error;
407 
408 	error = 0;
409 	uart_lock(sc->sc_hwmtx);
410 	switch (request) {
411 	case UART_IOCTL_BREAK:
412 		break;
413 	case UART_IOCTL_BAUD:
414 		*(int*)data = 115200;
415 		break;
416 	default:
417 		error = EINVAL;
418 		break;
419 	}
420 	uart_unlock(sc->sc_hwmtx);
421 
422 	return (error);
423 }
424 
425 static int
426 uart_pl011_bus_ipend(struct uart_softc *sc)
427 {
428 	struct uart_pl011_softc *psc;
429 	struct uart_bas *bas;
430 	uint32_t ints;
431 	int ipend;
432 
433 	psc = (struct uart_pl011_softc *)sc;
434 	bas = &sc->sc_bas;
435 
436 	uart_lock(sc->sc_hwmtx);
437 	ints = __uart_getreg(bas, UART_MIS);
438 	ipend = 0;
439 
440 	if (ints & (UART_RXREADY | RIS_RTIM))
441 		ipend |= SER_INT_RXREADY;
442 	if (ints & RIS_BE)
443 		ipend |= SER_INT_BREAK;
444 	if (ints & RIS_OE)
445 		ipend |= SER_INT_OVERRUN;
446 	if (ints & UART_TXEMPTY) {
447 		if (sc->sc_txbusy)
448 			ipend |= SER_INT_TXIDLE;
449 
450 		/* Disable TX interrupt */
451 		__uart_setreg(bas, UART_IMSC, psc->imsc & ~UART_TXEMPTY);
452 	}
453 
454 	uart_unlock(sc->sc_hwmtx);
455 
456 	return (ipend);
457 }
458 
459 static int
460 uart_pl011_bus_param(struct uart_softc *sc, int baudrate, int databits,
461     int stopbits, int parity)
462 {
463 
464 	uart_lock(sc->sc_hwmtx);
465 	uart_pl011_param(&sc->sc_bas, baudrate, databits, stopbits, parity);
466 	uart_unlock(sc->sc_hwmtx);
467 
468 	return (0);
469 }
470 
471 #ifdef FDT
472 static int
473 uart_pl011_bus_hwrev_fdt(struct uart_softc *sc)
474 {
475 	pcell_t node;
476 	uint32_t periphid;
477 
478 	/*
479 	 * The FIFO sizes vary depending on hardware; rev 2 and below have 16
480 	 * byte FIFOs, rev 3 and up are 32 byte.  The hardware rev is in the
481 	 * primecell periphid register, but we get a bit of drama, as always,
482 	 * with the bcm2835 (rpi), which claims to be rev 3, but has 16 byte
483 	 * FIFOs.  We check for both the old freebsd-historic and the proper
484 	 * bindings-defined compatible strings for bcm2835, and also check the
485 	 * workaround the linux drivers use for rpi3, which is to override the
486 	 * primecell periphid register value with a property.
487 	 */
488 	if (ofw_bus_is_compatible(sc->sc_dev, "brcm,bcm2835-pl011") ||
489 	    ofw_bus_is_compatible(sc->sc_dev, "broadcom,bcm2835-uart")) {
490 		return (2);
491 	} else {
492 		node = ofw_bus_get_node(sc->sc_dev);
493 		if (OF_getencprop(node, "arm,primecell-periphid", &periphid,
494 		    sizeof(periphid)) > 0) {
495 			return ((periphid >> 20) & 0x0f);
496 		}
497 	}
498 
499 	return (-1);
500 }
501 #endif
502 
503 static int
504 uart_pl011_bus_probe(struct uart_softc *sc)
505 {
506 	int hwrev;
507 
508 	hwrev = -1;
509 #ifdef FDT
510 	if (IS_FDT)
511 		hwrev = uart_pl011_bus_hwrev_fdt(sc);
512 #endif
513 	if (hwrev < 0)
514 		hwrev = __uart_getreg(&sc->sc_bas, UART_PIDREG_2) >> 4;
515 
516 	if (hwrev <= 2) {
517 		sc->sc_rxfifosz = FIFO_RX_SIZE_R2;
518 		sc->sc_txfifosz = FIFO_TX_SIZE_R2;
519 	} else {
520 		sc->sc_rxfifosz = FIFO_RX_SIZE_R3;
521 		sc->sc_txfifosz = FIFO_TX_SIZE_R3;
522 	}
523 
524 	device_set_desc(sc->sc_dev, "PrimeCell UART (PL011)");
525 
526 	return (0);
527 }
528 
529 static int
530 uart_pl011_bus_receive(struct uart_softc *sc)
531 {
532 	struct uart_bas *bas;
533 	uint32_t ints, xc;
534 	int rx;
535 
536 	bas = &sc->sc_bas;
537 	uart_lock(sc->sc_hwmtx);
538 
539 	for (;;) {
540 		ints = __uart_getreg(bas, UART_FR);
541 		if (ints & FR_RXFE)
542 			break;
543 		if (uart_rx_full(sc)) {
544 			sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN;
545 			break;
546 		}
547 
548 		xc = __uart_getreg(bas, UART_DR);
549 		rx = xc & 0xff;
550 
551 		if (xc & DR_FE)
552 			rx |= UART_STAT_FRAMERR;
553 		if (xc & DR_PE)
554 			rx |= UART_STAT_PARERR;
555 
556 		uart_rx_put(sc, rx);
557 	}
558 
559 	uart_unlock(sc->sc_hwmtx);
560 
561 	return (0);
562 }
563 
564 static int
565 uart_pl011_bus_setsig(struct uart_softc *sc, int sig)
566 {
567 
568 	return (0);
569 }
570 
571 static int
572 uart_pl011_bus_transmit(struct uart_softc *sc)
573 {
574 	struct uart_pl011_softc *psc;
575 	struct uart_bas *bas;
576 	int i;
577 
578 	psc = (struct uart_pl011_softc *)sc;
579 	bas = &sc->sc_bas;
580 	uart_lock(sc->sc_hwmtx);
581 
582 	for (i = 0; i < sc->sc_txdatasz; i++) {
583 		__uart_setreg(bas, UART_DR, sc->sc_txbuf[i]);
584 		uart_barrier(bas);
585 	}
586 
587 	/* Mark busy and enable TX interrupt */
588 	sc->sc_txbusy = 1;
589 	__uart_setreg(bas, UART_IMSC, psc->imsc);
590 
591 	uart_unlock(sc->sc_hwmtx);
592 
593 	return (0);
594 }
595 
596 static void
597 uart_pl011_bus_grab(struct uart_softc *sc)
598 {
599 	struct uart_pl011_softc *psc;
600 	struct uart_bas *bas;
601 
602 	psc = (struct uart_pl011_softc *)sc;
603 	bas = &sc->sc_bas;
604 
605 	/* Disable interrupts on switch to polling */
606 	uart_lock(sc->sc_hwmtx);
607 	__uart_setreg(bas, UART_IMSC, psc->imsc & ~IMSC_MASK_ALL);
608 	uart_unlock(sc->sc_hwmtx);
609 }
610 
611 static void
612 uart_pl011_bus_ungrab(struct uart_softc *sc)
613 {
614 	struct uart_pl011_softc *psc;
615 	struct uart_bas *bas;
616 
617 	psc = (struct uart_pl011_softc *)sc;
618 	bas = &sc->sc_bas;
619 
620 	/* Switch to using interrupts while not grabbed */
621 	uart_lock(sc->sc_hwmtx);
622 	__uart_setreg(bas, UART_IMSC, psc->imsc);
623 	uart_unlock(sc->sc_hwmtx);
624 }
625