xref: /netbsd-src/sys/dev/ic/dwiic.c (revision bdc22b2e01993381dcefeff2bc9b56ca75a4235c)
1 /* $NetBSD: dwiic.c,v 1.1 2017/12/10 17:12:54 bouyer Exp $ */
2 
3 /* $OpenBSD dwiic.c,v 1.24 2017/08/17 20:41:16 kettenis Exp $ */
4 
5 /*-
6  * Copyright (c) 2017 The NetBSD Foundation, Inc.
7  * All rights reserved.
8  *
9  * This code is derived from software contributed to The NetBSD Foundation
10  * by Manuel Bouyer.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
23  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
25  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31  * POSSIBILITY OF SUCH DAMAGE.
32  */
33 /*
34  * Synopsys DesignWare I2C controller
35  *
36  * Copyright (c) 2015, 2016 joshua stein <jcs@openbsd.org>
37  *
38  * Permission to use, copy, modify, and/or distribute this software for any
39  * purpose with or without fee is hereby granted, provided that the above
40  * copyright notice and this permission notice appear in all copies.
41  *
42  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
43  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
44  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
45  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
46  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
47  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
48  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
49  */
50 
51 #include <sys/cdefs.h>
52 __KERNEL_RCSID(0, "$NetBSD: dwiic.c,v 1.1 2017/12/10 17:12:54 bouyer Exp $");
53 
54 #include <sys/param.h>
55 #include <sys/bus.h>
56 #include <sys/device.h>
57 #include <sys/kernel.h>
58 #include <sys/systm.h>
59 
60 #include <dev/ic/dwiic_var.h>
61 
62 //#define DWIIC_DEBUG
63 
64 #ifdef DWIIC_DEBUG
65 #define DPRINTF(x) printf x
66 #else
67 #define DPRINTF(x)
68 #endif
69 
70 /* register offsets */
71 #define DW_IC_CON		0x0
72 #define DW_IC_TAR		0x4
73 #define DW_IC_DATA_CMD		0x10
74 #define DW_IC_SS_SCL_HCNT	0x14
75 #define DW_IC_SS_SCL_LCNT	0x18
76 #define DW_IC_FS_SCL_HCNT	0x1c
77 #define DW_IC_FS_SCL_LCNT	0x20
78 #define DW_IC_INTR_STAT		0x2c
79 #define DW_IC_INTR_MASK		0x30
80 #define DW_IC_RAW_INTR_STAT	0x34
81 #define DW_IC_RX_TL		0x38
82 #define DW_IC_TX_TL		0x3c
83 #define DW_IC_CLR_INTR		0x40
84 #define DW_IC_CLR_RX_UNDER	0x44
85 #define DW_IC_CLR_RX_OVER	0x48
86 #define DW_IC_CLR_TX_OVER	0x4c
87 #define DW_IC_CLR_RD_REQ	0x50
88 #define DW_IC_CLR_TX_ABRT	0x54
89 #define DW_IC_CLR_RX_DONE	0x58
90 #define DW_IC_CLR_ACTIVITY	0x5c
91 #define DW_IC_CLR_STOP_DET	0x60
92 #define DW_IC_CLR_START_DET	0x64
93 #define DW_IC_CLR_GEN_CALL	0x68
94 #define DW_IC_ENABLE		0x6c
95 #define DW_IC_STATUS		0x70
96 #define DW_IC_TXFLR		0x74
97 #define DW_IC_RXFLR		0x78
98 #define DW_IC_SDA_HOLD		0x7c
99 #define DW_IC_TX_ABRT_SOURCE	0x80
100 #define DW_IC_ENABLE_STATUS	0x9c
101 #define DW_IC_COMP_PARAM_1	0xf4
102 #define DW_IC_COMP_VERSION	0xf8
103 #define DW_IC_SDA_HOLD_MIN_VERS	0x3131312A
104 #define DW_IC_COMP_TYPE		0xfc
105 #define DW_IC_COMP_TYPE_VALUE	0x44570140
106 
107 #define DW_IC_CON_MASTER	0x1
108 #define DW_IC_CON_SPEED_STD	0x2
109 #define DW_IC_CON_SPEED_FAST	0x4
110 #define DW_IC_CON_10BITADDR_MASTER 0x10
111 #define DW_IC_CON_RESTART_EN	0x20
112 #define DW_IC_CON_SLAVE_DISABLE	0x40
113 
114 #define DW_IC_DATA_CMD_READ	0x100
115 #define DW_IC_DATA_CMD_STOP	0x200
116 #define DW_IC_DATA_CMD_RESTART	0x400
117 
118 #define DW_IC_INTR_RX_UNDER	0x001
119 #define DW_IC_INTR_RX_OVER	0x002
120 #define DW_IC_INTR_RX_FULL	0x004
121 #define DW_IC_INTR_TX_OVER	0x008
122 #define DW_IC_INTR_TX_EMPTY	0x010
123 #define DW_IC_INTR_RD_REQ	0x020
124 #define DW_IC_INTR_TX_ABRT	0x040
125 #define DW_IC_INTR_RX_DONE	0x080
126 #define DW_IC_INTR_ACTIVITY	0x100
127 #define DW_IC_INTR_STOP_DET	0x200
128 #define DW_IC_INTR_START_DET	0x400
129 #define DW_IC_INTR_GEN_CALL	0x800
130 
131 #define DW_IC_STATUS_ACTIVITY	0x1
132 
133 /* hardware abort codes from the DW_IC_TX_ABRT_SOURCE register */
134 #define ABRT_7B_ADDR_NOACK	0
135 #define ABRT_10ADDR1_NOACK	1
136 #define ABRT_10ADDR2_NOACK	2
137 #define ABRT_TXDATA_NOACK	3
138 #define ABRT_GCALL_NOACK	4
139 #define ABRT_GCALL_READ		5
140 #define ABRT_SBYTE_ACKDET	7
141 #define ABRT_SBYTE_NORSTRT	9
142 #define ABRT_10B_RD_NORSTRT	10
143 #define ABRT_MASTER_DIS		11
144 #define ARB_LOST		12
145 
146 static int	dwiic_init(struct dwiic_softc *);
147 static void	dwiic_enable(struct dwiic_softc *, bool);
148 static int	dwiic_i2c_acquire_bus(void *, int);
149 static void	dwiic_i2c_release_bus(void *, int);
150 static uint32_t	dwiic_read(struct dwiic_softc *, int);
151 static void	dwiic_write(struct dwiic_softc *, int, uint32_t);
152 static int	dwiic_i2c_exec(void *, i2c_op_t, i2c_addr_t, const void *,
153 		    size_t, void *, size_t, int);
154 
155 bool
156 dwiic_attach(struct dwiic_softc *sc)
157 {
158 	if (sc->sc_power != NULL) {
159 		if (!sc->sc_power(sc, 1)) {
160 			aprint_error_dev(sc->sc_dev, "failed to power up\n");
161 			return 0;
162 		}
163 	}
164 
165 	/* fetch timing parameters */
166 	if (sc->ss_hcnt == 0)
167 		sc->ss_hcnt = dwiic_read(sc, DW_IC_SS_SCL_HCNT);
168 	if (sc->ss_lcnt == 0)
169 		sc->ss_lcnt = dwiic_read(sc, DW_IC_SS_SCL_LCNT);
170 	if (sc->fs_hcnt == 0)
171 		sc->fs_hcnt = dwiic_read(sc, DW_IC_FS_SCL_HCNT);
172 	if (sc->fs_lcnt == 0)
173 		sc->fs_lcnt = dwiic_read(sc, DW_IC_FS_SCL_LCNT);
174 	if (sc->sda_hold_time == 0)
175 		sc->sda_hold_time = dwiic_read(sc, DW_IC_SDA_HOLD);
176 
177 	if (dwiic_init(sc)) {
178 		aprint_error_dev(sc->sc_dev, "failed initializing\n");
179 		return 0;
180 	}
181 
182 	/* leave the controller disabled */
183 	dwiic_write(sc, DW_IC_INTR_MASK, 0);
184 	dwiic_enable(sc, 0);
185 	dwiic_read(sc, DW_IC_CLR_INTR);
186 
187 	mutex_init(&sc->sc_i2c_lock, MUTEX_DEFAULT, IPL_NONE);
188 	mutex_init(&sc->sc_int_lock, MUTEX_DEFAULT, IPL_VM);
189 	cv_init(&sc->sc_int_readwait, "dwiicr");
190 	cv_init(&sc->sc_int_writewait, "dwiicw");
191 
192 	/* setup and attach iic bus */
193 	sc->sc_i2c_tag.ic_cookie = sc;
194 	sc->sc_i2c_tag.ic_acquire_bus = dwiic_i2c_acquire_bus;
195 	sc->sc_i2c_tag.ic_release_bus = dwiic_i2c_release_bus;
196 	sc->sc_i2c_tag.ic_exec = dwiic_i2c_exec;
197 
198 	sc->sc_iba.iba_tag = &sc->sc_i2c_tag;
199 
200 	config_found_ia(sc->sc_dev, "i2cbus", &sc->sc_iba, iicbus_print);
201 	return 1;
202 }
203 
204 int
205 dwiic_detach(device_t self, int flags)
206 {
207 	struct dwiic_softc *sc = device_private(self);
208 
209 	dwiic_enable(sc, 0);
210 	if (sc->sc_ih != NULL) {
211 		intr_disestablish(sc->sc_ih);
212 		sc->sc_ih = NULL;
213 	}
214 
215 	return 0;
216 }
217 
218 bool
219 dwiic_suspend(device_t self, const pmf_qual_t *qual)
220 {
221 	struct dwiic_softc *sc = device_private(self);
222 
223 	/* disable controller */
224 	dwiic_enable(sc, 0);
225 
226 	/* disable interrupts */
227 	dwiic_write(sc, DW_IC_INTR_MASK, 0);
228 	dwiic_read(sc, DW_IC_CLR_INTR);
229 	if (sc->sc_power != NULL) {
230 		if (!sc->sc_power(sc, 0)) {
231 			aprint_error_dev(sc->sc_dev, "failed to power off\n");
232 		}
233 	}
234 	return true;
235 }
236 
237 bool
238 dwiic_resume(device_t self, const pmf_qual_t *qual)
239 {
240 	struct dwiic_softc *sc = device_private(self);
241 	if (sc->sc_power != NULL) {
242 		if (!sc->sc_power(sc, 1)) {
243 			aprint_error_dev(sc->sc_dev, "failed to power up\n");
244 			return false;
245 		}
246 	}
247 	dwiic_init(sc);
248 	return true;
249 }
250 
251 static uint32_t
252 dwiic_read(struct dwiic_softc *sc, int offset)
253 {
254 	u_int32_t b = bus_space_read_4(sc->sc_iot, sc->sc_ioh, offset);
255 
256 	DPRINTF(("%s: read at 0x%x = 0x%x\n", device_xname(sc->sc_dev), offset, b));
257 
258 	return b;
259 }
260 
261 static void
262 dwiic_write(struct dwiic_softc *sc, int offset, uint32_t val)
263 {
264 	bus_space_write_4(sc->sc_iot, sc->sc_ioh, offset, val);
265 
266 	DPRINTF(("%s: write at 0x%x: 0x%x\n", device_xname(sc->sc_dev), offset,
267 	    val));
268 }
269 
270 static int
271 dwiic_i2c_acquire_bus(void *cookie, int flags)
272 {
273 	struct dwiic_softc *sc = cookie;
274 
275 	if (cold || sc->sc_poll || (flags & I2C_F_POLL))
276 		return (0);
277 
278 	mutex_enter(&sc->sc_i2c_lock);
279 	return 1;
280 }
281 
282 void
283 dwiic_i2c_release_bus(void *cookie, int flags)
284 {
285 	struct dwiic_softc *sc = cookie;
286 
287 	if (cold || sc->sc_poll || (flags & I2C_F_POLL))
288 		return;
289 
290 	mutex_exit(&sc->sc_i2c_lock);
291 }
292 
293 static int
294 dwiic_init(struct dwiic_softc *sc)
295 {
296 	uint32_t reg;
297 
298 	/* make sure we're talking to a device we know */
299 	reg = dwiic_read(sc, DW_IC_COMP_TYPE);
300 	if (reg != DW_IC_COMP_TYPE_VALUE) {
301 		DPRINTF(("%s: invalid component type 0x%x\n",
302 		    device_xname(sc->sc_dev), reg));
303 		return 1;
304 	}
305 
306 	/* disable the adapter */
307 	dwiic_enable(sc, 0);
308 
309 	/* write standard-mode SCL timing parameters */
310 	dwiic_write(sc, DW_IC_SS_SCL_HCNT, sc->ss_hcnt);
311 	dwiic_write(sc, DW_IC_SS_SCL_LCNT, sc->ss_lcnt);
312 
313 	/* and fast-mode SCL timing parameters */
314 	dwiic_write(sc, DW_IC_FS_SCL_HCNT, sc->fs_hcnt);
315 	dwiic_write(sc, DW_IC_FS_SCL_LCNT, sc->fs_lcnt);
316 
317 	/* SDA hold time */
318 	reg = dwiic_read(sc, DW_IC_COMP_VERSION);
319 	if (reg >= DW_IC_SDA_HOLD_MIN_VERS)
320 		dwiic_write(sc, DW_IC_SDA_HOLD, sc->sda_hold_time);
321 
322 	/* FIFO threshold levels */
323 	sc->tx_fifo_depth = 32;
324 	sc->rx_fifo_depth = 32;
325 	dwiic_write(sc, DW_IC_TX_TL, sc->tx_fifo_depth / 2);
326 	dwiic_write(sc, DW_IC_RX_TL, 0);
327 
328 	/* configure as i2c master with fast speed */
329 	sc->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
330 	    DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST;
331 	dwiic_write(sc, DW_IC_CON, sc->master_cfg);
332 
333 	return 0;
334 }
335 
336 static void
337 dwiic_enable(struct dwiic_softc *sc, bool enable)
338 {
339 	int retries;
340 
341 	for (retries = 100; retries > 0; retries--) {
342 		dwiic_write(sc, DW_IC_ENABLE, enable);
343 		if ((dwiic_read(sc, DW_IC_ENABLE_STATUS) & 1) == enable)
344 			return;
345 
346 		DELAY(25);
347 	}
348 
349 	aprint_error_dev(sc->sc_dev, "failed to %sable\n",
350 	    (enable ? "en" : "dis"));
351 }
352 
353 static int
354 dwiic_i2c_exec(void *cookie, i2c_op_t op, i2c_addr_t addr, const void *cmdbuf,
355     size_t cmdlen, void *buf, size_t len, int flags)
356 {
357 	struct dwiic_softc *sc = cookie;
358 	u_int32_t ic_con, st, cmd, resp;
359 	int retries, tx_limit, rx_avail, x, readpos;
360 	const uint8_t *bcmd;
361 	uint8_t *bdata;
362 
363 	if (cold || sc->sc_poll)
364 		flags |= I2C_F_POLL;
365 
366 	DPRINTF(("%s: %s: op %d, addr 0x%02x, cmdlen %zu, len %zu, "
367 	    "flags 0x%02x\n", device_xname(sc->sc_dev), __func__, op, addr, cmdlen,
368 	    len, flags));
369 
370 	/* setup transfer */
371 	sc->sc_i2c_xfer.op = op;
372 	sc->sc_i2c_xfer.buf = buf;
373 	sc->sc_i2c_xfer.len = len;
374 	sc->sc_i2c_xfer.flags = flags;
375 	sc->sc_i2c_xfer.error = 0;
376 
377 	/* wait for bus to be idle */
378 	for (retries = 100; retries > 0; retries--) {
379 		st = dwiic_read(sc, DW_IC_STATUS);
380 		if (!(st & DW_IC_STATUS_ACTIVITY))
381 			break;
382 		DELAY(1000);
383 	}
384 	DPRINTF(("%s: %s: status 0x%x\n", device_xname(sc->sc_dev), __func__, st));
385 	if (st & DW_IC_STATUS_ACTIVITY) {
386 		return (1);
387 	}
388 
389 	/* disable controller */
390 	dwiic_enable(sc, 0);
391 
392 	/* set slave address */
393 	ic_con = dwiic_read(sc, DW_IC_CON);
394 	ic_con &= ~DW_IC_CON_10BITADDR_MASTER;
395 	dwiic_write(sc, DW_IC_CON, ic_con);
396 	dwiic_write(sc, DW_IC_TAR, addr);
397 
398 	/* disable interrupts */
399 	dwiic_write(sc, DW_IC_INTR_MASK, 0);
400 	dwiic_read(sc, DW_IC_CLR_INTR);
401 
402 	/* enable controller */
403 	dwiic_enable(sc, 1);
404 
405 	/* wait until the controller is ready for commands */
406 	if (flags & I2C_F_POLL)
407 		DELAY(200);
408 	else {
409 		mutex_enter(&sc->sc_int_lock);
410 		dwiic_read(sc, DW_IC_CLR_INTR);
411 		dwiic_write(sc, DW_IC_INTR_MASK, DW_IC_INTR_TX_EMPTY);
412 
413 		if (cv_timedwait(&sc->sc_int_writewait,
414 		    &sc->sc_int_lock, hz / 2) != 0)
415 			aprint_error_dev(sc->sc_dev,
416 			    "timed out waiting for tx_empty intr\n");
417 		dwiic_write(sc, DW_IC_INTR_MASK, 0);
418 		dwiic_read(sc, DW_IC_CLR_INTR);
419 		mutex_exit(&sc->sc_int_lock);
420 	}
421 
422 	/* send our command, one byte at a time */
423 	if (cmdlen > 0) {
424 		bcmd = (const void *)cmdbuf;
425 
426 		DPRINTF(("%s: %s: sending cmd (len %zu):", device_xname(sc->sc_dev),
427 		    __func__, cmdlen));
428 		for (x = 0; x < cmdlen; x++)
429 			DPRINTF((" %02x", bcmd[x]));
430 		DPRINTF(("\n"));
431 
432 		tx_limit = sc->tx_fifo_depth - dwiic_read(sc, DW_IC_TXFLR);
433 		if (cmdlen > tx_limit) {
434 			/* TODO */
435 			aprint_error_dev(sc->sc_dev, "can't write %zu (> %d)\n",
436 			    cmdlen, tx_limit);
437 			sc->sc_i2c_xfer.error = 1;
438 			return (1);
439 		}
440 
441 		for (x = 0; x < cmdlen; x++) {
442 			cmd = bcmd[x];
443 			/*
444 			 * Generate STOP condition if this is the last
445 			 * byte of the transfer.
446 			 */
447 			if (x == (cmdlen - 1) && len == 0 && I2C_OP_STOP_P(op))
448 				cmd |= DW_IC_DATA_CMD_STOP;
449 			dwiic_write(sc, DW_IC_DATA_CMD, cmd);
450 		}
451 	}
452 
453 	bdata = (void *)buf;
454 	x = readpos = 0;
455 	tx_limit = sc->tx_fifo_depth - dwiic_read(sc, DW_IC_TXFLR);
456 
457 	DPRINTF(("%s: %s: need to read %zu bytes, can send %d read reqs\n",
458 		device_xname(sc->sc_dev), __func__, len, tx_limit));
459 
460 	while (x < len) {
461 		if (I2C_OP_WRITE_P(op))
462 			cmd = bdata[x];
463 		else
464 			cmd = DW_IC_DATA_CMD_READ;
465 
466 		/*
467 		 * Generate RESTART condition if we're reversing
468 		 * direction.
469 		 */
470 		if (x == 0 && cmdlen > 0 && I2C_OP_READ_P(op))
471 			cmd |= DW_IC_DATA_CMD_RESTART;
472 		/*
473 		 * Generate STOP conditon on the last byte of the
474 		 * transfer.
475 		 */
476 		if (x == (len - 1) && I2C_OP_STOP_P(op))
477 			cmd |= DW_IC_DATA_CMD_STOP;
478 
479 		dwiic_write(sc, DW_IC_DATA_CMD, cmd);
480 
481 		tx_limit--;
482 		x++;
483 
484 		/*
485 		 * As TXFLR fills up, we need to clear it out by reading all
486 		 * available data.
487 		 */
488 		while (tx_limit == 0 || x == len) {
489 			DPRINTF(("%s: %s: tx_limit %d, sent %d read reqs\n",
490 			    device_xname(sc->sc_dev), __func__, tx_limit, x));
491 
492 			if (flags & I2C_F_POLL) {
493 				for (retries = 100; retries > 0; retries--) {
494 					rx_avail = dwiic_read(sc, DW_IC_RXFLR);
495 					if (rx_avail > 0)
496 						break;
497 					DELAY(50);
498 				}
499 			} else {
500 				mutex_enter(&sc->sc_int_lock);
501 				dwiic_read(sc, DW_IC_CLR_INTR);
502 				dwiic_write(sc, DW_IC_INTR_MASK,
503 				    DW_IC_INTR_RX_FULL);
504 
505 				if (cv_timedwait(&sc->sc_int_readwait,
506 				    &sc->sc_int_lock, hz / 2) != 0)
507 					aprint_error_dev(sc->sc_dev,
508 					    "timed out waiting for "
509 					    "rx_full intr\n");
510 
511 				dwiic_write(sc, DW_IC_INTR_MASK, 0);
512 				dwiic_read(sc, DW_IC_CLR_INTR);
513 				mutex_exit(&sc->sc_int_lock);
514 				rx_avail = dwiic_read(sc, DW_IC_RXFLR);
515 			}
516 
517 			if (rx_avail == 0) {
518 				aprint_error_dev(sc->sc_dev,
519 				    "timed out reading remaining %d\n",
520 				    (int)(len - 1 - readpos));
521 				sc->sc_i2c_xfer.error = 1;
522 				return (1);
523 			}
524 
525 			DPRINTF(("%s: %s: %d avail to read (%zu remaining)\n",
526 			    device_xname(sc->sc_dev), __func__, rx_avail,
527 			    len - readpos));
528 
529 			while (rx_avail > 0) {
530 				resp = dwiic_read(sc, DW_IC_DATA_CMD);
531 				if (readpos < len) {
532 					bdata[readpos] = resp;
533 					readpos++;
534 				}
535 				rx_avail--;
536 			}
537 
538 			if (readpos >= len)
539 				break;
540 
541 			DPRINTF(("%s: still need to read %d bytes\n",
542 			    device_xname(sc->sc_dev), (int)(len - readpos)));
543 			tx_limit = sc->tx_fifo_depth -
544 			    dwiic_read(sc, DW_IC_TXFLR);
545 		}
546 	}
547 
548 	return 0;
549 }
550 
551 static uint32_t
552 dwiic_read_clear_intrbits(struct dwiic_softc *sc)
553 {
554        uint32_t stat;
555 
556        stat = dwiic_read(sc, DW_IC_INTR_STAT);
557 
558        if (stat & DW_IC_INTR_RX_UNDER)
559 	       dwiic_read(sc, DW_IC_CLR_RX_UNDER);
560        if (stat & DW_IC_INTR_RX_OVER)
561 	       dwiic_read(sc, DW_IC_CLR_RX_OVER);
562        if (stat & DW_IC_INTR_TX_OVER)
563 	       dwiic_read(sc, DW_IC_CLR_TX_OVER);
564        if (stat & DW_IC_INTR_RD_REQ)
565 	       dwiic_read(sc, DW_IC_CLR_RD_REQ);
566        if (stat & DW_IC_INTR_TX_ABRT)
567 	       dwiic_read(sc, DW_IC_CLR_TX_ABRT);
568        if (stat & DW_IC_INTR_RX_DONE)
569 	       dwiic_read(sc, DW_IC_CLR_RX_DONE);
570        if (stat & DW_IC_INTR_ACTIVITY)
571 	       dwiic_read(sc, DW_IC_CLR_ACTIVITY);
572        if (stat & DW_IC_INTR_STOP_DET)
573 	       dwiic_read(sc, DW_IC_CLR_STOP_DET);
574        if (stat & DW_IC_INTR_START_DET)
575 	       dwiic_read(sc, DW_IC_CLR_START_DET);
576        if (stat & DW_IC_INTR_GEN_CALL)
577 	       dwiic_read(sc, DW_IC_CLR_GEN_CALL);
578 
579        return stat;
580 }
581 
582 int
583 dwiic_intr(void *arg)
584 {
585 	struct dwiic_softc *sc = arg;
586 	uint32_t en, stat;
587 
588 	en = dwiic_read(sc, DW_IC_ENABLE);
589 	/* probably for the other controller */
590 	if (!en)
591 		return 0;
592 
593 	stat = dwiic_read_clear_intrbits(sc);
594 	DPRINTF(("%s: %s: enabled=0x%x stat=0x%x\n", device_xname(sc->sc_dev),
595 	    __func__, en, stat));
596 	if (!(stat & ~DW_IC_INTR_ACTIVITY))
597 		return 1;
598 
599 	if (stat & DW_IC_INTR_TX_ABRT)
600 		sc->sc_i2c_xfer.error = 1;
601 
602 	if (sc->sc_i2c_xfer.flags & I2C_F_POLL)
603 		DPRINTF(("%s: %s: intr in poll mode?\n", device_xname(sc->sc_dev),
604 		    __func__));
605 	else {
606 		mutex_enter(&sc->sc_int_lock);
607 		if (stat & DW_IC_INTR_RX_FULL) {
608 			dwiic_write(sc, DW_IC_INTR_MASK, 0);
609 			DPRINTF(("%s: %s: waking up reader\n",
610 			    device_xname(sc->sc_dev), __func__));
611 			cv_signal(&sc->sc_int_readwait);
612 		}
613 		if (stat & DW_IC_INTR_TX_EMPTY) {
614 			dwiic_write(sc, DW_IC_INTR_MASK, 0);
615 			DPRINTF(("%s: %s: waking up writer\n",
616 			    device_xname(sc->sc_dev), __func__));
617 			cv_signal(&sc->sc_int_writewait);
618 		}
619 		mutex_exit(&sc->sc_int_lock);
620 	}
621 
622 	return 1;
623 }
624