xref: /openbmc/u-boot/drivers/i2c/fsl_i2c.c (revision 8f240a3b)
1 /*
2  * Copyright 2006,2009 Freescale Semiconductor, Inc.
3  *
4  * 2012, Heiko Schocher, DENX Software Engineering, hs@denx.de.
5  * Changes for multibus/multiadapter I2C support.
6  *
7  * SPDX-License-Identifier:	GPL-2.0
8  */
9 
10 #include <common.h>
11 #include <command.h>
12 #include <i2c.h>		/* Functional interface */
13 #include <asm/io.h>
14 #include <asm/fsl_i2c.h>	/* HW definitions */
15 #include <dm.h>
16 #include <mapmem.h>
17 
18 /* The maximum number of microseconds we will wait until another master has
19  * released the bus.  If not defined in the board header file, then use a
20  * generic value.
21  */
22 #ifndef CONFIG_I2C_MBB_TIMEOUT
23 #define CONFIG_I2C_MBB_TIMEOUT	100000
24 #endif
25 
26 /* The maximum number of microseconds we will wait for a read or write
27  * operation to complete.  If not defined in the board header file, then use a
28  * generic value.
29  */
30 #ifndef CONFIG_I2C_TIMEOUT
31 #define CONFIG_I2C_TIMEOUT	100000
32 #endif
33 
34 #define I2C_READ_BIT  1
35 #define I2C_WRITE_BIT 0
36 
37 DECLARE_GLOBAL_DATA_PTR;
38 
39 #ifndef CONFIG_DM_I2C
40 static const struct fsl_i2c_base *i2c_base[4] = {
41 	(struct fsl_i2c_base *)(CONFIG_SYS_IMMR + CONFIG_SYS_FSL_I2C_OFFSET),
42 #ifdef CONFIG_SYS_FSL_I2C2_OFFSET
43 	(struct fsl_i2c_base *)(CONFIG_SYS_IMMR + CONFIG_SYS_FSL_I2C2_OFFSET),
44 #endif
45 #ifdef CONFIG_SYS_FSL_I2C3_OFFSET
46 	(struct fsl_i2c_base *)(CONFIG_SYS_IMMR + CONFIG_SYS_FSL_I2C3_OFFSET),
47 #endif
48 #ifdef CONFIG_SYS_FSL_I2C4_OFFSET
49 	(struct fsl_i2c_base *)(CONFIG_SYS_IMMR + CONFIG_SYS_FSL_I2C4_OFFSET)
50 #endif
51 };
52 #endif
53 
54 /* I2C speed map for a DFSR value of 1 */
55 
56 #ifdef __M68K__
57 /*
58  * Map I2C frequency dividers to FDR and DFSR values
59  *
60  * This structure is used to define the elements of a table that maps I2C
61  * frequency divider (I2C clock rate divided by I2C bus speed) to a value to be
62  * programmed into the Frequency Divider Ratio (FDR) and Digital Filter
63  * Sampling Rate (DFSR) registers.
64  *
65  * The actual table should be defined in the board file, and it must be called
66  * fsl_i2c_speed_map[].
67  *
68  * The last entry of the table must have a value of {-1, X}, where X is same
69  * FDR/DFSR values as the second-to-last entry.  This guarantees that any
70  * search through the array will always find a match.
71  *
72  * The values of the divider must be in increasing numerical order, i.e.
73  * fsl_i2c_speed_map[x+1].divider > fsl_i2c_speed_map[x].divider.
74  *
75  * For this table, the values are based on a value of 1 for the DFSR
76  * register.  See the application note AN2919 "Determining the I2C Frequency
77  * Divider Ratio for SCL"
78  *
79  * ColdFire I2C frequency dividers for FDR values are different from
80  * PowerPC. The protocol to use the I2C module is still the same.
81  * A different table is defined and are based on MCF5xxx user manual.
82  *
83  */
84 static const struct {
85 	unsigned short divider;
86 	u8 fdr;
87 } fsl_i2c_speed_map[] = {
88 	{20, 32}, {22, 33}, {24, 34}, {26, 35},
89 	{28, 0}, {28, 36}, {30, 1}, {32, 37},
90 	{34, 2}, {36, 38}, {40, 3}, {40, 39},
91 	{44, 4}, {48, 5}, {48, 40}, {56, 6},
92 	{56, 41}, {64, 42}, {68, 7}, {72, 43},
93 	{80, 8}, {80, 44}, {88, 9}, {96, 41},
94 	{104, 10}, {112, 42}, {128, 11}, {128, 43},
95 	{144, 12}, {160, 13}, {160, 48}, {192, 14},
96 	{192, 49}, {224, 50}, {240, 15}, {256, 51},
97 	{288, 16}, {320, 17}, {320, 52}, {384, 18},
98 	{384, 53}, {448, 54}, {480, 19}, {512, 55},
99 	{576, 20}, {640, 21}, {640, 56}, {768, 22},
100 	{768, 57}, {960, 23}, {896, 58}, {1024, 59},
101 	{1152, 24}, {1280, 25}, {1280, 60}, {1536, 26},
102 	{1536, 61}, {1792, 62}, {1920, 27}, {2048, 63},
103 	{2304, 28}, {2560, 29}, {3072, 30}, {3840, 31},
104 	{-1, 31}
105 };
106 #endif
107 
108 /**
109  * Set the I2C bus speed for a given I2C device
110  *
111  * @param base: the I2C device registers
112  * @i2c_clk: I2C bus clock frequency
113  * @speed: the desired speed of the bus
114  *
115  * The I2C device must be stopped before calling this function.
116  *
117  * The return value is the actual bus speed that is set.
118  */
119 static uint set_i2c_bus_speed(const struct fsl_i2c_base *base,
120 			      uint i2c_clk, uint speed)
121 {
122 	ushort divider = min(i2c_clk / speed, (uint)USHRT_MAX);
123 
124 	/*
125 	 * We want to choose an FDR/DFSR that generates an I2C bus speed that
126 	 * is equal to or lower than the requested speed.  That means that we
127 	 * want the first divider that is equal to or greater than the
128 	 * calculated divider.
129 	 */
130 #ifdef __PPC__
131 	u8 dfsr, fdr = 0x31; /* Default if no FDR found */
132 	/* a, b and dfsr matches identifiers A,B and C respectively in AN2919 */
133 	ushort a, b, ga, gb;
134 	ulong c_div, est_div;
135 
136 #ifdef CONFIG_FSL_I2C_CUSTOM_DFSR
137 	dfsr = CONFIG_FSL_I2C_CUSTOM_DFSR;
138 #else
139 	/* Condition 1: dfsr <= 50/T */
140 	dfsr = (5 * (i2c_clk / 1000)) / 100000;
141 #endif
142 #ifdef CONFIG_FSL_I2C_CUSTOM_FDR
143 	fdr = CONFIG_FSL_I2C_CUSTOM_FDR;
144 	speed = i2c_clk / divider; /* Fake something */
145 #else
146 	debug("Requested speed:%d, i2c_clk:%d\n", speed, i2c_clk);
147 	if (!dfsr)
148 		dfsr = 1;
149 
150 	est_div = ~0;
151 	for (ga = 0x4, a = 10; a <= 30; ga++, a += 2) {
152 		for (gb = 0; gb < 8; gb++) {
153 			b = 16 << gb;
154 			c_div = b * (a + ((3 * dfsr) / b) * 2);
155 			if (c_div > divider && c_div < est_div) {
156 				ushort bin_gb, bin_ga;
157 
158 				est_div = c_div;
159 				bin_gb = gb << 2;
160 				bin_ga = (ga & 0x3) | ((ga & 0x4) << 3);
161 				fdr = bin_gb | bin_ga;
162 				speed = i2c_clk / est_div;
163 
164 				debug("FDR: 0x%.2x, ", fdr);
165 				debug("div: %ld, ", est_div);
166 				debug("ga: 0x%x, gb: 0x%x, ", ga, gb);
167 				debug("a: %d, b: %d, speed: %d\n", a, b, speed);
168 
169 				/* Condition 2 not accounted for */
170 				debug("Tr <= %d ns\n",
171 				      (b - 3 * dfsr) * 1000000 /
172 				      (i2c_clk / 1000));
173 			}
174 		}
175 		if (a == 20)
176 			a += 2;
177 		if (a == 24)
178 			a += 4;
179 	}
180 	debug("divider: %d, est_div: %ld, DFSR: %d\n", divider, est_div, dfsr);
181 	debug("FDR: 0x%.2x, speed: %d\n", fdr, speed);
182 #endif
183 	writeb(dfsr, &base->dfsrr);	/* set default filter */
184 	writeb(fdr, &base->fdr);	/* set bus speed */
185 #else
186 	uint i;
187 
188 	for (i = 0; i < ARRAY_SIZE(fsl_i2c_speed_map); i++)
189 		if (fsl_i2c_speed_map[i].divider >= divider) {
190 			u8 fdr;
191 
192 			fdr = fsl_i2c_speed_map[i].fdr;
193 			speed = i2c_clk / fsl_i2c_speed_map[i].divider;
194 			writeb(fdr, &base->fdr);	/* set bus speed */
195 
196 			break;
197 		}
198 #endif
199 	return speed;
200 }
201 
202 #ifndef CONFIG_DM_I2C
203 static uint get_i2c_clock(int bus)
204 {
205 	if (bus)
206 		return gd->arch.i2c2_clk;	/* I2C2 clock */
207 	else
208 		return gd->arch.i2c1_clk;	/* I2C1 clock */
209 }
210 #endif
211 
212 static int fsl_i2c_fixup(const struct fsl_i2c_base *base)
213 {
214 	const unsigned long long timeout = usec2ticks(CONFIG_I2C_MBB_TIMEOUT);
215 	unsigned long long timeval = 0;
216 	int ret = -1;
217 	uint flags = 0;
218 
219 #ifdef CONFIG_SYS_FSL_ERRATUM_I2C_A004447
220 	uint svr = get_svr();
221 
222 	if ((SVR_SOC_VER(svr) == SVR_8548 && IS_SVR_REV(svr, 3, 1)) ||
223 	    (SVR_REV(svr) <= CONFIG_SYS_FSL_A004447_SVR_REV))
224 		flags = I2C_CR_BIT6;
225 #endif
226 
227 	writeb(I2C_CR_MEN | I2C_CR_MSTA, &base->cr);
228 
229 	timeval = get_ticks();
230 	while (!(readb(&base->sr) & I2C_SR_MBB)) {
231 		if ((get_ticks() - timeval) > timeout)
232 			goto err;
233 	}
234 
235 	if (readb(&base->sr) & I2C_SR_MAL) {
236 		/* SDA is stuck low */
237 		writeb(0, &base->cr);
238 		udelay(100);
239 		writeb(I2C_CR_MSTA | flags, &base->cr);
240 		writeb(I2C_CR_MEN | I2C_CR_MSTA | flags, &base->cr);
241 	}
242 
243 	readb(&base->dr);
244 
245 	timeval = get_ticks();
246 	while (!(readb(&base->sr) & I2C_SR_MIF)) {
247 		if ((get_ticks() - timeval) > timeout)
248 			goto err;
249 	}
250 	ret = 0;
251 
252 err:
253 	writeb(I2C_CR_MEN | flags, &base->cr);
254 	writeb(0, &base->sr);
255 	udelay(100);
256 
257 	return ret;
258 }
259 
260 static void __i2c_init(const struct fsl_i2c_base *base, int speed, int
261 		       slaveadd, int i2c_clk, int busnum)
262 {
263 	const unsigned long long timeout = usec2ticks(CONFIG_I2C_MBB_TIMEOUT);
264 	unsigned long long timeval;
265 
266 #ifdef CONFIG_SYS_I2C_INIT_BOARD
267 	/* Call board specific i2c bus reset routine before accessing the
268 	 * environment, which might be in a chip on that bus. For details
269 	 * about this problem see doc/I2C_Edge_Conditions.
270 	 */
271 	i2c_init_board();
272 #endif
273 	writeb(0, &base->cr);		/* stop I2C controller */
274 	udelay(5);			/* let it shutdown in peace */
275 	set_i2c_bus_speed(base, i2c_clk, speed);
276 	writeb(slaveadd << 1, &base->adr);/* write slave address */
277 	writeb(0x0, &base->sr);		/* clear status register */
278 	writeb(I2C_CR_MEN, &base->cr);	/* start I2C controller */
279 
280 	timeval = get_ticks();
281 	while (readb(&base->sr) & I2C_SR_MBB) {
282 		if ((get_ticks() - timeval) < timeout)
283 			continue;
284 
285 		if (fsl_i2c_fixup(base))
286 			debug("i2c_init: BUS#%d failed to init\n",
287 			      busnum);
288 
289 		break;
290 	}
291 }
292 
293 static int i2c_wait4bus(const struct fsl_i2c_base *base)
294 {
295 	unsigned long long timeval = get_ticks();
296 	const unsigned long long timeout = usec2ticks(CONFIG_I2C_MBB_TIMEOUT);
297 
298 	while (readb(&base->sr) & I2C_SR_MBB) {
299 		if ((get_ticks() - timeval) > timeout)
300 			return -1;
301 	}
302 
303 	return 0;
304 }
305 
306 static int i2c_wait(const struct fsl_i2c_base *base, int write)
307 {
308 	u32 csr;
309 	unsigned long long timeval = get_ticks();
310 	const unsigned long long timeout = usec2ticks(CONFIG_I2C_TIMEOUT);
311 
312 	do {
313 		csr = readb(&base->sr);
314 		if (!(csr & I2C_SR_MIF))
315 			continue;
316 		/* Read again to allow register to stabilise */
317 		csr = readb(&base->sr);
318 
319 		writeb(0x0, &base->sr);
320 
321 		if (csr & I2C_SR_MAL) {
322 			debug("%s: MAL\n", __func__);
323 			return -1;
324 		}
325 
326 		if (!(csr & I2C_SR_MCF))	{
327 			debug("%s: unfinished\n", __func__);
328 			return -1;
329 		}
330 
331 		if (write == I2C_WRITE_BIT && (csr & I2C_SR_RXAK)) {
332 			debug("%s: No RXACK\n", __func__);
333 			return -1;
334 		}
335 
336 		return 0;
337 	} while ((get_ticks() - timeval) < timeout);
338 
339 	debug("%s: timed out\n", __func__);
340 	return -1;
341 }
342 
343 static int i2c_write_addr(const struct fsl_i2c_base *base, u8 dev,
344 			  u8 dir, int rsta)
345 {
346 	writeb(I2C_CR_MEN | I2C_CR_MSTA | I2C_CR_MTX
347 	       | (rsta ? I2C_CR_RSTA : 0),
348 	       &base->cr);
349 
350 	writeb((dev << 1) | dir, &base->dr);
351 
352 	if (i2c_wait(base, I2C_WRITE_BIT) < 0)
353 		return 0;
354 
355 	return 1;
356 }
357 
358 static int __i2c_write_data(const struct fsl_i2c_base *base, u8 *data,
359 			    int length)
360 {
361 	int i;
362 
363 	for (i = 0; i < length; i++) {
364 		writeb(data[i], &base->dr);
365 
366 		if (i2c_wait(base, I2C_WRITE_BIT) < 0)
367 			break;
368 	}
369 
370 	return i;
371 }
372 
373 static int __i2c_read_data(const struct fsl_i2c_base *base, u8 *data,
374 			   int length)
375 {
376 	int i;
377 
378 	writeb(I2C_CR_MEN | I2C_CR_MSTA | ((length == 1) ? I2C_CR_TXAK : 0),
379 	       &base->cr);
380 
381 	/* dummy read */
382 	readb(&base->dr);
383 
384 	for (i = 0; i < length; i++) {
385 		if (i2c_wait(base, I2C_READ_BIT) < 0)
386 			break;
387 
388 		/* Generate ack on last next to last byte */
389 		if (i == length - 2)
390 			writeb(I2C_CR_MEN | I2C_CR_MSTA | I2C_CR_TXAK,
391 			       &base->cr);
392 
393 		/* Do not generate stop on last byte */
394 		if (i == length - 1)
395 			writeb(I2C_CR_MEN | I2C_CR_MSTA | I2C_CR_MTX,
396 			       &base->cr);
397 
398 		data[i] = readb(&base->dr);
399 	}
400 
401 	return i;
402 }
403 
404 static int __i2c_read(const struct fsl_i2c_base *base, u8 chip_addr, u8 *offset,
405 		      int olen, u8 *data, int dlen)
406 {
407 	int ret = -1; /* signal error */
408 
409 	if (i2c_wait4bus(base) < 0)
410 		return -1;
411 
412 	/* Some drivers use offset lengths in excess of 4 bytes. These drivers
413 	 * adhere to the following convention:
414 	 * - the offset length is passed as negative (that is, the absolute
415 	 *   value of olen is the actual offset length)
416 	 * - the offset itself is passed in data, which is overwritten by the
417 	 *   subsequent read operation
418 	 */
419 	if (olen < 0) {
420 		if (i2c_write_addr(base, chip_addr, I2C_WRITE_BIT, 0) != 0)
421 			ret = __i2c_write_data(base, data, -olen);
422 
423 		if (ret != -olen)
424 			return -1;
425 
426 		if (dlen && i2c_write_addr(base, chip_addr,
427 					   I2C_READ_BIT, 1) != 0)
428 			ret = __i2c_read_data(base, data, dlen);
429 	} else {
430 		if ((!dlen || olen > 0) &&
431 		    i2c_write_addr(base, chip_addr, I2C_WRITE_BIT, 0) != 0  &&
432 		    __i2c_write_data(base, offset, olen) == olen)
433 			ret = 0; /* No error so far */
434 
435 		if (dlen && i2c_write_addr(base, chip_addr, I2C_READ_BIT,
436 					   olen ? 1 : 0) != 0)
437 			ret = __i2c_read_data(base, data, dlen);
438 	}
439 
440 	writeb(I2C_CR_MEN, &base->cr);
441 
442 	if (i2c_wait4bus(base)) /* Wait until STOP */
443 		debug("i2c_read: wait4bus timed out\n");
444 
445 	if (ret == dlen)
446 		return 0;
447 
448 	return -1;
449 }
450 
451 static int __i2c_write(const struct fsl_i2c_base *base, u8 chip_addr,
452 		       u8 *offset, int olen, u8 *data, int dlen)
453 {
454 	int ret = -1; /* signal error */
455 
456 	if (i2c_wait4bus(base) < 0)
457 		return -1;
458 
459 	if (i2c_write_addr(base, chip_addr, I2C_WRITE_BIT, 0) != 0 &&
460 	    __i2c_write_data(base, offset, olen) == olen) {
461 		ret = __i2c_write_data(base, data, dlen);
462 	}
463 
464 	writeb(I2C_CR_MEN, &base->cr);
465 	if (i2c_wait4bus(base)) /* Wait until STOP */
466 		debug("i2c_write: wait4bus timed out\n");
467 
468 	if (ret == dlen)
469 		return 0;
470 
471 	return -1;
472 }
473 
474 static int __i2c_probe_chip(const struct fsl_i2c_base *base, uchar chip)
475 {
476 	/* For unknown reason the controller will ACK when
477 	 * probing for a slave with the same address, so skip
478 	 * it.
479 	 */
480 	if (chip == (readb(&base->adr) >> 1))
481 		return -1;
482 
483 	return __i2c_read(base, chip, 0, 0, NULL, 0);
484 }
485 
486 static uint __i2c_set_bus_speed(const struct fsl_i2c_base *base,
487 				uint speed, int i2c_clk)
488 {
489 	writeb(0, &base->cr);		/* stop controller */
490 	set_i2c_bus_speed(base, i2c_clk, speed);
491 	writeb(I2C_CR_MEN, &base->cr);	/* start controller */
492 
493 	return 0;
494 }
495 
496 #ifndef CONFIG_DM_I2C
497 static void fsl_i2c_init(struct i2c_adapter *adap, int speed, int slaveadd)
498 {
499 	__i2c_init(i2c_base[adap->hwadapnr], speed, slaveadd,
500 		   get_i2c_clock(adap->hwadapnr), adap->hwadapnr);
501 }
502 
503 static int fsl_i2c_probe_chip(struct i2c_adapter *adap, uchar chip)
504 {
505 	return __i2c_probe_chip(i2c_base[adap->hwadapnr], chip);
506 }
507 
508 static int fsl_i2c_read(struct i2c_adapter *adap, u8 chip_addr, uint offset,
509 			int olen, u8 *data, int dlen)
510 {
511 	u8 *o = (u8 *)&offset;
512 
513 	return __i2c_read(i2c_base[adap->hwadapnr], chip_addr, &o[4 - olen],
514 			  olen, data, dlen);
515 }
516 
517 static int fsl_i2c_write(struct i2c_adapter *adap, u8 chip_addr, uint offset,
518 			 int olen, u8 *data, int dlen)
519 {
520 	u8 *o = (u8 *)&offset;
521 
522 	return __i2c_write(i2c_base[adap->hwadapnr], chip_addr, &o[4 - olen],
523 			   olen, data, dlen);
524 }
525 
526 static uint fsl_i2c_set_bus_speed(struct i2c_adapter *adap, uint speed)
527 {
528 	return __i2c_set_bus_speed(i2c_base[adap->hwadapnr], speed,
529 				   get_i2c_clock(adap->hwadapnr));
530 }
531 
532 /*
533  * Register fsl i2c adapters
534  */
535 U_BOOT_I2C_ADAP_COMPLETE(fsl_0, fsl_i2c_init, fsl_i2c_probe_chip, fsl_i2c_read,
536 			 fsl_i2c_write, fsl_i2c_set_bus_speed,
537 			 CONFIG_SYS_FSL_I2C_SPEED, CONFIG_SYS_FSL_I2C_SLAVE,
538 			 0)
539 #ifdef CONFIG_SYS_FSL_I2C2_OFFSET
540 U_BOOT_I2C_ADAP_COMPLETE(fsl_1, fsl_i2c_init, fsl_i2c_probe_chip, fsl_i2c_read,
541 			 fsl_i2c_write, fsl_i2c_set_bus_speed,
542 			 CONFIG_SYS_FSL_I2C2_SPEED, CONFIG_SYS_FSL_I2C2_SLAVE,
543 			 1)
544 #endif
545 #ifdef CONFIG_SYS_FSL_I2C3_OFFSET
546 U_BOOT_I2C_ADAP_COMPLETE(fsl_2, fsl_i2c_init, fsl_i2c_probe_chip, fsl_i2c_read,
547 			 fsl_i2c_write, fsl_i2c_set_bus_speed,
548 			 CONFIG_SYS_FSL_I2C3_SPEED, CONFIG_SYS_FSL_I2C3_SLAVE,
549 			 2)
550 #endif
551 #ifdef CONFIG_SYS_FSL_I2C4_OFFSET
552 U_BOOT_I2C_ADAP_COMPLETE(fsl_3, fsl_i2c_init, fsl_i2c_probe_chip, fsl_i2c_read,
553 			 fsl_i2c_write, fsl_i2c_set_bus_speed,
554 			 CONFIG_SYS_FSL_I2C4_SPEED, CONFIG_SYS_FSL_I2C4_SLAVE,
555 			 3)
556 #endif
557 #else /* CONFIG_DM_I2C */
558 static int fsl_i2c_probe_chip(struct udevice *bus, u32 chip_addr,
559 			      u32 chip_flags)
560 {
561 	struct fsl_i2c_dev *dev = dev_get_priv(bus);
562 
563 	return __i2c_probe_chip(dev->base, chip_addr);
564 }
565 
566 static int fsl_i2c_set_bus_speed(struct udevice *bus, uint speed)
567 {
568 	struct fsl_i2c_dev *dev = dev_get_priv(bus);
569 
570 	return __i2c_set_bus_speed(dev->base, speed, dev->i2c_clk);
571 }
572 
573 static int fsl_i2c_ofdata_to_platdata(struct udevice *bus)
574 {
575 	struct fsl_i2c_dev *dev = dev_get_priv(bus);
576 	fdt_addr_t addr;
577 
578 	addr = dev_read_u32_default(bus, "reg", -1);
579 
580 	dev->base = map_sysmem(CONFIG_SYS_IMMR + addr, sizeof(struct fsl_i2c_base));
581 
582 	if (!dev->base)
583 		return -ENOMEM;
584 
585 	dev->index = dev_read_u32_default(bus, "cell-index", -1);
586 	dev->slaveadd = dev_read_u32_default(bus, "u-boot,i2c-slave-addr",
587 					     0x7f);
588 	dev->speed = dev_read_u32_default(bus, "clock-frequency", 400000);
589 
590 	dev->i2c_clk = dev->index ? gd->arch.i2c2_clk : gd->arch.i2c1_clk;
591 
592 	return 0;
593 }
594 
595 static int fsl_i2c_probe(struct udevice *bus)
596 {
597 	struct fsl_i2c_dev *dev = dev_get_priv(bus);
598 
599 	__i2c_init(dev->base, dev->speed, dev->slaveadd, dev->i2c_clk,
600 		   dev->index);
601 	return 0;
602 }
603 
604 static int fsl_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
605 {
606 	struct fsl_i2c_dev *dev = dev_get_priv(bus);
607 	struct i2c_msg *dmsg, *omsg, dummy;
608 
609 	memset(&dummy, 0, sizeof(struct i2c_msg));
610 
611 	/* We expect either two messages (one with an offset and one with the
612 	 * actual data) or one message (just data)
613 	 */
614 	if (nmsgs > 2 || nmsgs == 0) {
615 		debug("%s: Only one or two messages are supported.", __func__);
616 		return -1;
617 	}
618 
619 	omsg = nmsgs == 1 ? &dummy : msg;
620 	dmsg = nmsgs == 1 ? msg : msg + 1;
621 
622 	if (dmsg->flags & I2C_M_RD)
623 		return __i2c_read(dev->base, dmsg->addr, omsg->buf, omsg->len,
624 				  dmsg->buf, dmsg->len);
625 	else
626 		return __i2c_write(dev->base, dmsg->addr, omsg->buf, omsg->len,
627 				   dmsg->buf, dmsg->len);
628 }
629 
630 static const struct dm_i2c_ops fsl_i2c_ops = {
631 	.xfer           = fsl_i2c_xfer,
632 	.probe_chip     = fsl_i2c_probe_chip,
633 	.set_bus_speed  = fsl_i2c_set_bus_speed,
634 };
635 
636 static const struct udevice_id fsl_i2c_ids[] = {
637 	{ .compatible = "fsl-i2c", },
638 	{ /* sentinel */ }
639 };
640 
641 U_BOOT_DRIVER(i2c_fsl) = {
642 	.name = "i2c_fsl",
643 	.id = UCLASS_I2C,
644 	.of_match = fsl_i2c_ids,
645 	.probe = fsl_i2c_probe,
646 	.ofdata_to_platdata = fsl_i2c_ofdata_to_platdata,
647 	.priv_auto_alloc_size = sizeof(struct fsl_i2c_dev),
648 	.ops = &fsl_i2c_ops,
649 };
650 
651 #endif /* CONFIG_DM_I2C */
652