xref: /openbmc/u-boot/drivers/i2c/mxc_i2c.c (revision 6451223a)
1 /*
2  * i2c driver for Freescale i.MX series
3  *
4  * (c) 2007 Pengutronix, Sascha Hauer <s.hauer@pengutronix.de>
5  * (c) 2011 Marek Vasut <marek.vasut@gmail.com>
6  *
7  * Based on i2c-imx.c from linux kernel:
8  *  Copyright (C) 2005 Torsten Koschorrek <koschorrek at synertronixx.de>
9  *  Copyright (C) 2005 Matthias Blaschke <blaschke at synertronixx.de>
10  *  Copyright (C) 2007 RightHand Technologies, Inc.
11  *  Copyright (C) 2008 Darius Augulis <darius.augulis at teltonika.lt>
12  *
13  *
14  * SPDX-License-Identifier:	GPL-2.0+
15  */
16 
17 #include <common.h>
18 #include <asm/arch/clock.h>
19 #include <asm/arch/imx-regs.h>
20 #include <asm/errno.h>
21 #include <asm/imx-common/mxc_i2c.h>
22 #include <asm/io.h>
23 #include <i2c.h>
24 #include <watchdog.h>
25 #include <dm.h>
26 #include <fdtdec.h>
27 
28 DECLARE_GLOBAL_DATA_PTR;
29 
30 #define I2C_QUIRK_FLAG		(1 << 0)
31 
32 #define IMX_I2C_REGSHIFT	2
33 #define VF610_I2C_REGSHIFT	0
34 /* Register index */
35 #define IADR	0
36 #define IFDR	1
37 #define I2CR	2
38 #define I2SR	3
39 #define I2DR	4
40 
41 #define I2CR_IIEN	(1 << 6)
42 #define I2CR_MSTA	(1 << 5)
43 #define I2CR_MTX	(1 << 4)
44 #define I2CR_TX_NO_AK	(1 << 3)
45 #define I2CR_RSTA	(1 << 2)
46 
47 #define I2SR_ICF	(1 << 7)
48 #define I2SR_IBB	(1 << 5)
49 #define I2SR_IAL	(1 << 4)
50 #define I2SR_IIF	(1 << 1)
51 #define I2SR_RX_NO_AK	(1 << 0)
52 
53 #ifdef I2C_QUIRK_REG
54 #define I2CR_IEN	(0 << 7)
55 #define I2CR_IDIS	(1 << 7)
56 #define I2SR_IIF_CLEAR	(1 << 1)
57 #else
58 #define I2CR_IEN	(1 << 7)
59 #define I2CR_IDIS	(0 << 7)
60 #define I2SR_IIF_CLEAR	(0 << 1)
61 #endif
62 
63 #if defined(CONFIG_HARD_I2C) && !defined(CONFIG_SYS_I2C_BASE)
64 #error "define CONFIG_SYS_I2C_BASE to use the mxc_i2c driver"
65 #endif
66 
67 #ifdef I2C_QUIRK_REG
68 static u16 i2c_clk_div[60][2] = {
69 	{ 20,	0x00 }, { 22,	0x01 }, { 24,	0x02 }, { 26,	0x03 },
70 	{ 28,	0x04 },	{ 30,	0x05 },	{ 32,	0x09 }, { 34,	0x06 },
71 	{ 36,	0x0A }, { 40,	0x07 }, { 44,	0x0C }, { 48,	0x0D },
72 	{ 52,	0x43 },	{ 56,	0x0E }, { 60,	0x45 }, { 64,	0x12 },
73 	{ 68,	0x0F },	{ 72,	0x13 },	{ 80,	0x14 },	{ 88,	0x15 },
74 	{ 96,	0x19 },	{ 104,	0x16 },	{ 112,	0x1A },	{ 128,	0x17 },
75 	{ 136,	0x4F }, { 144,	0x1C },	{ 160,	0x1D }, { 176,	0x55 },
76 	{ 192,	0x1E }, { 208,	0x56 },	{ 224,	0x22 }, { 228,	0x24 },
77 	{ 240,	0x1F },	{ 256,	0x23 }, { 288,	0x5C },	{ 320,	0x25 },
78 	{ 384,	0x26 }, { 448,	0x2A },	{ 480,	0x27 }, { 512,	0x2B },
79 	{ 576,	0x2C },	{ 640,	0x2D },	{ 768,	0x31 }, { 896,	0x32 },
80 	{ 960,	0x2F },	{ 1024,	0x33 },	{ 1152,	0x34 }, { 1280,	0x35 },
81 	{ 1536,	0x36 }, { 1792,	0x3A },	{ 1920,	0x37 },	{ 2048,	0x3B },
82 	{ 2304,	0x3C },	{ 2560,	0x3D },	{ 3072,	0x3E }, { 3584,	0x7A },
83 	{ 3840,	0x3F }, { 4096,	0x7B }, { 5120,	0x7D },	{ 6144,	0x7E },
84 };
85 #else
86 static u16 i2c_clk_div[50][2] = {
87 	{ 22,	0x20 }, { 24,	0x21 }, { 26,	0x22 }, { 28,	0x23 },
88 	{ 30,	0x00 }, { 32,	0x24 }, { 36,	0x25 }, { 40,	0x26 },
89 	{ 42,	0x03 }, { 44,	0x27 }, { 48,	0x28 }, { 52,	0x05 },
90 	{ 56,	0x29 }, { 60,	0x06 }, { 64,	0x2A }, { 72,	0x2B },
91 	{ 80,	0x2C }, { 88,	0x09 }, { 96,	0x2D }, { 104,	0x0A },
92 	{ 112,	0x2E }, { 128,	0x2F }, { 144,	0x0C }, { 160,	0x30 },
93 	{ 192,	0x31 }, { 224,	0x32 }, { 240,	0x0F }, { 256,	0x33 },
94 	{ 288,	0x10 }, { 320,	0x34 }, { 384,	0x35 }, { 448,	0x36 },
95 	{ 480,	0x13 }, { 512,	0x37 }, { 576,	0x14 }, { 640,	0x38 },
96 	{ 768,	0x39 }, { 896,	0x3A }, { 960,	0x17 }, { 1024,	0x3B },
97 	{ 1152,	0x18 }, { 1280,	0x3C }, { 1536,	0x3D }, { 1792,	0x3E },
98 	{ 1920,	0x1B }, { 2048,	0x3F }, { 2304,	0x1C }, { 2560,	0x1D },
99 	{ 3072,	0x1E }, { 3840,	0x1F }
100 };
101 #endif
102 
103 #ifndef CONFIG_SYS_MXC_I2C1_SPEED
104 #define CONFIG_SYS_MXC_I2C1_SPEED 100000
105 #endif
106 #ifndef CONFIG_SYS_MXC_I2C2_SPEED
107 #define CONFIG_SYS_MXC_I2C2_SPEED 100000
108 #endif
109 #ifndef CONFIG_SYS_MXC_I2C3_SPEED
110 #define CONFIG_SYS_MXC_I2C3_SPEED 100000
111 #endif
112 #ifndef CONFIG_SYS_MXC_I2C4_SPEED
113 #define CONFIG_SYS_MXC_I2C4_SPEED 100000
114 #endif
115 
116 #ifndef CONFIG_SYS_MXC_I2C1_SLAVE
117 #define CONFIG_SYS_MXC_I2C1_SLAVE 0
118 #endif
119 #ifndef CONFIG_SYS_MXC_I2C2_SLAVE
120 #define CONFIG_SYS_MXC_I2C2_SLAVE 0
121 #endif
122 #ifndef CONFIG_SYS_MXC_I2C3_SLAVE
123 #define CONFIG_SYS_MXC_I2C3_SLAVE 0
124 #endif
125 #ifndef CONFIG_SYS_MXC_I2C4_SLAVE
126 #define CONFIG_SYS_MXC_I2C4_SLAVE 0
127 #endif
128 
129 /*
130  * Calculate and set proper clock divider
131  */
132 static uint8_t i2c_imx_get_clk(struct mxc_i2c_bus *i2c_bus, unsigned int rate)
133 {
134 	unsigned int i2c_clk_rate;
135 	unsigned int div;
136 	u8 clk_div;
137 
138 #if defined(CONFIG_MX31)
139 	struct clock_control_regs *sc_regs =
140 		(struct clock_control_regs *)CCM_BASE;
141 
142 	/* start the required I2C clock */
143 	writel(readl(&sc_regs->cgr0) | (3 << CONFIG_SYS_I2C_CLK_OFFSET),
144 		&sc_regs->cgr0);
145 #endif
146 
147 	/* Divider value calculation */
148 	i2c_clk_rate = mxc_get_clock(MXC_I2C_CLK);
149 	div = (i2c_clk_rate + rate - 1) / rate;
150 	if (div < i2c_clk_div[0][0])
151 		clk_div = 0;
152 	else if (div > i2c_clk_div[ARRAY_SIZE(i2c_clk_div) - 1][0])
153 		clk_div = ARRAY_SIZE(i2c_clk_div) - 1;
154 	else
155 		for (clk_div = 0; i2c_clk_div[clk_div][0] < div; clk_div++)
156 			;
157 
158 	/* Store divider value */
159 	return clk_div;
160 }
161 
162 /*
163  * Set I2C Bus speed
164  */
165 static int bus_i2c_set_bus_speed(struct mxc_i2c_bus *i2c_bus, int speed)
166 {
167 	ulong base = i2c_bus->base;
168 	bool quirk = i2c_bus->driver_data & I2C_QUIRK_FLAG ? true : false;
169 	u8 clk_idx = i2c_imx_get_clk(i2c_bus, speed);
170 	u8 idx = i2c_clk_div[clk_idx][1];
171 	int reg_shift = quirk ? VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
172 
173 	if (!base)
174 		return -ENODEV;
175 
176 	/* Store divider value */
177 	writeb(idx, base + (IFDR << reg_shift));
178 
179 	/* Reset module */
180 	writeb(I2CR_IDIS, base + (I2CR << reg_shift));
181 	writeb(0, base + (I2SR << reg_shift));
182 	return 0;
183 }
184 
185 #define ST_BUS_IDLE (0 | (I2SR_IBB << 8))
186 #define ST_BUS_BUSY (I2SR_IBB | (I2SR_IBB << 8))
187 #define ST_IIF (I2SR_IIF | (I2SR_IIF << 8))
188 
189 static int wait_for_sr_state(struct mxc_i2c_bus *i2c_bus, unsigned state)
190 {
191 	unsigned sr;
192 	ulong elapsed;
193 	bool quirk = i2c_bus->driver_data & I2C_QUIRK_FLAG ? true : false;
194 	int reg_shift = quirk ? VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
195 	ulong base = i2c_bus->base;
196 	ulong start_time = get_timer(0);
197 	for (;;) {
198 		sr = readb(base + (I2SR << reg_shift));
199 		if (sr & I2SR_IAL) {
200 			if (quirk)
201 				writeb(sr | I2SR_IAL, base +
202 				       (I2SR << reg_shift));
203 			else
204 				writeb(sr & ~I2SR_IAL, base +
205 				       (I2SR << reg_shift));
206 			printf("%s: Arbitration lost sr=%x cr=%x state=%x\n",
207 				__func__, sr, readb(base + (I2CR << reg_shift)),
208 				state);
209 			return -ERESTART;
210 		}
211 		if ((sr & (state >> 8)) == (unsigned char)state)
212 			return sr;
213 		WATCHDOG_RESET();
214 		elapsed = get_timer(start_time);
215 		if (elapsed > (CONFIG_SYS_HZ / 10))	/* .1 seconds */
216 			break;
217 	}
218 	printf("%s: failed sr=%x cr=%x state=%x\n", __func__,
219 	       sr, readb(base + (I2CR << reg_shift)), state);
220 	return -ETIMEDOUT;
221 }
222 
223 static int tx_byte(struct mxc_i2c_bus *i2c_bus, u8 byte)
224 {
225 	int ret;
226 	int reg_shift = i2c_bus->driver_data & I2C_QUIRK_FLAG ?
227 			VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
228 	ulong base = i2c_bus->base;
229 
230 	writeb(I2SR_IIF_CLEAR, base + (I2SR << reg_shift));
231 	writeb(byte, base + (I2DR << reg_shift));
232 
233 	ret = wait_for_sr_state(i2c_bus, ST_IIF);
234 	if (ret < 0)
235 		return ret;
236 	if (ret & I2SR_RX_NO_AK)
237 		return -ENODEV;
238 	return 0;
239 }
240 
241 /*
242  * Stub implementations for outer i2c slave operations.
243  */
244 void __i2c_force_reset_slave(void)
245 {
246 }
247 void i2c_force_reset_slave(void)
248 	__attribute__((weak, alias("__i2c_force_reset_slave")));
249 
250 /*
251  * Stop I2C transaction
252  */
253 static void i2c_imx_stop(struct mxc_i2c_bus *i2c_bus)
254 {
255 	int ret;
256 	int reg_shift = i2c_bus->driver_data & I2C_QUIRK_FLAG ?
257 			VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
258 	ulong base = i2c_bus->base;
259 	unsigned int temp = readb(base + (I2CR << reg_shift));
260 
261 	temp &= ~(I2CR_MSTA | I2CR_MTX);
262 	writeb(temp, base + (I2CR << reg_shift));
263 	ret = wait_for_sr_state(i2c_bus, ST_BUS_IDLE);
264 	if (ret < 0)
265 		printf("%s:trigger stop failed\n", __func__);
266 }
267 
268 /*
269  * Send start signal, chip address and
270  * write register address
271  */
272 static int i2c_init_transfer_(struct mxc_i2c_bus *i2c_bus, u8 chip,
273 			      u32 addr, int alen)
274 {
275 	unsigned int temp;
276 	int ret;
277 	bool quirk = i2c_bus->driver_data & I2C_QUIRK_FLAG ? true : false;
278 	ulong base = i2c_bus->base;
279 	int reg_shift = quirk ? VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
280 
281 	/* Reset i2c slave */
282 	i2c_force_reset_slave();
283 
284 	/* Enable I2C controller */
285 	if (quirk)
286 		ret = readb(base + (I2CR << reg_shift)) & I2CR_IDIS;
287 	else
288 		ret = !(readb(base + (I2CR << reg_shift)) & I2CR_IEN);
289 
290 	if (ret) {
291 		writeb(I2CR_IEN, base + (I2CR << reg_shift));
292 		/* Wait for controller to be stable */
293 		udelay(50);
294 	}
295 
296 	if (readb(base + (IADR << reg_shift)) == (chip << 1))
297 		writeb((chip << 1) ^ 2, base + (IADR << reg_shift));
298 	writeb(I2SR_IIF_CLEAR, base + (I2SR << reg_shift));
299 	ret = wait_for_sr_state(i2c_bus, ST_BUS_IDLE);
300 	if (ret < 0)
301 		return ret;
302 
303 	/* Start I2C transaction */
304 	temp = readb(base + (I2CR << reg_shift));
305 	temp |= I2CR_MSTA;
306 	writeb(temp, base + (I2CR << reg_shift));
307 
308 	ret = wait_for_sr_state(i2c_bus, ST_BUS_BUSY);
309 	if (ret < 0)
310 		return ret;
311 
312 	temp |= I2CR_MTX | I2CR_TX_NO_AK;
313 	writeb(temp, base + (I2CR << reg_shift));
314 
315 	/* write slave address */
316 	ret = tx_byte(i2c_bus, chip << 1);
317 	if (ret < 0)
318 		return ret;
319 
320 	while (alen--) {
321 		ret = tx_byte(i2c_bus, (addr >> (alen * 8)) & 0xff);
322 		if (ret < 0)
323 			return ret;
324 	}
325 	return 0;
326 }
327 
328 #ifndef CONFIG_DM_I2C
329 int i2c_idle_bus(struct mxc_i2c_bus *i2c_bus)
330 {
331 	if (i2c_bus && i2c_bus->idle_bus_fn)
332 		return i2c_bus->idle_bus_fn(i2c_bus->idle_bus_data);
333 	return 0;
334 }
335 #else
336 /*
337  * Since pinmux is not supported, implement a weak function here.
338  * You can implement your i2c_bus_idle in board file. When pinctrl
339  * is supported, this can be removed.
340  */
341 int __i2c_idle_bus(struct mxc_i2c_bus *i2c_bus)
342 {
343 	return 0;
344 }
345 
346 int i2c_idle_bus(struct mxc_i2c_bus *i2c_bus)
347 	__attribute__((weak, alias("__i2c_idle_bus")));
348 #endif
349 
350 static int i2c_init_transfer(struct mxc_i2c_bus *i2c_bus, u8 chip,
351 			     u32 addr, int alen)
352 {
353 	int retry;
354 	int ret;
355 	int reg_shift = i2c_bus->driver_data & I2C_QUIRK_FLAG ?
356 			VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
357 
358 	if (!i2c_bus->base)
359 		return -ENODEV;
360 
361 	for (retry = 0; retry < 3; retry++) {
362 		ret = i2c_init_transfer_(i2c_bus, chip, addr, alen);
363 		if (ret >= 0)
364 			return 0;
365 		i2c_imx_stop(i2c_bus);
366 		if (ret == -ENODEV)
367 			return ret;
368 
369 		printf("%s: failed for chip 0x%x retry=%d\n", __func__, chip,
370 				retry);
371 		if (ret != -ERESTART)
372 			/* Disable controller */
373 			writeb(I2CR_IDIS, i2c_bus->base + (I2CR << reg_shift));
374 		udelay(100);
375 		if (i2c_idle_bus(i2c_bus) < 0)
376 			break;
377 	}
378 	printf("%s: give up i2c_regs=0x%lx\n", __func__, i2c_bus->base);
379 	return ret;
380 }
381 
382 
383 static int i2c_write_data(struct mxc_i2c_bus *i2c_bus, u8 chip, const u8 *buf,
384 			  int len)
385 {
386 	int i, ret = 0;
387 
388 	debug("i2c_write_data: chip=0x%x, len=0x%x\n", chip, len);
389 	debug("write_data: ");
390 	/* use rc for counter */
391 	for (i = 0; i < len; ++i)
392 		debug(" 0x%02x", buf[i]);
393 	debug("\n");
394 
395 	for (i = 0; i < len; i++) {
396 		ret = tx_byte(i2c_bus, buf[i]);
397 		if (ret < 0) {
398 			debug("i2c_write_data(): rc=%d\n", ret);
399 			break;
400 		}
401 	}
402 
403 	return ret;
404 }
405 
406 static int i2c_read_data(struct mxc_i2c_bus *i2c_bus, uchar chip, uchar *buf,
407 			 int len)
408 {
409 	int ret;
410 	unsigned int temp;
411 	int i;
412 	int reg_shift = i2c_bus->driver_data & I2C_QUIRK_FLAG ?
413 			VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
414 	ulong base = i2c_bus->base;
415 
416 	debug("i2c_read_data: chip=0x%x, len=0x%x\n", chip, len);
417 
418 	/* setup bus to read data */
419 	temp = readb(base + (I2CR << reg_shift));
420 	temp &= ~(I2CR_MTX | I2CR_TX_NO_AK);
421 	if (len == 1)
422 		temp |= I2CR_TX_NO_AK;
423 	writeb(temp, base + (I2CR << reg_shift));
424 	writeb(I2SR_IIF_CLEAR, base + (I2SR << reg_shift));
425 	/* dummy read to clear ICF */
426 	readb(base + (I2DR << reg_shift));
427 
428 	/* read data */
429 	for (i = 0; i < len; i++) {
430 		ret = wait_for_sr_state(i2c_bus, ST_IIF);
431 		if (ret < 0) {
432 			debug("i2c_read_data(): ret=%d\n", ret);
433 			i2c_imx_stop(i2c_bus);
434 			return ret;
435 		}
436 
437 		/*
438 		 * It must generate STOP before read I2DR to prevent
439 		 * controller from generating another clock cycle
440 		 */
441 		if (i == (len - 1)) {
442 			i2c_imx_stop(i2c_bus);
443 		} else if (i == (len - 2)) {
444 			temp = readb(base + (I2CR << reg_shift));
445 			temp |= I2CR_TX_NO_AK;
446 			writeb(temp, base + (I2CR << reg_shift));
447 		}
448 		writeb(I2SR_IIF_CLEAR, base + (I2SR << reg_shift));
449 		buf[i] = readb(base + (I2DR << reg_shift));
450 	}
451 
452 	/* reuse ret for counter*/
453 	for (ret = 0; ret < len; ++ret)
454 		debug(" 0x%02x", buf[ret]);
455 	debug("\n");
456 
457 	i2c_imx_stop(i2c_bus);
458 	return 0;
459 }
460 
461 #ifndef CONFIG_DM_I2C
462 /*
463  * Read data from I2C device
464  */
465 static int bus_i2c_read(struct mxc_i2c_bus *i2c_bus, u8 chip, u32 addr,
466 			int alen, u8 *buf, int len)
467 {
468 	int ret = 0;
469 	u32 temp;
470 	int reg_shift = i2c_bus->driver_data & I2C_QUIRK_FLAG ?
471 		VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
472 	ulong base = i2c_bus->base;
473 
474 	ret = i2c_init_transfer(i2c_bus, chip, addr, alen);
475 	if (ret < 0)
476 		return ret;
477 
478 	temp = readb(base + (I2CR << reg_shift));
479 	temp |= I2CR_RSTA;
480 	writeb(temp, base + (I2CR << reg_shift));
481 
482 	ret = tx_byte(i2c_bus, (chip << 1) | 1);
483 	if (ret < 0) {
484 		i2c_imx_stop(i2c_bus);
485 		return ret;
486 	}
487 
488 	ret = i2c_read_data(i2c_bus, chip, buf, len);
489 
490 	i2c_imx_stop(i2c_bus);
491 	return ret;
492 }
493 
494 /*
495  * Write data to I2C device
496  */
497 static int bus_i2c_write(struct mxc_i2c_bus *i2c_bus, u8 chip, u32 addr,
498 			 int alen, const u8 *buf, int len)
499 {
500 	int ret = 0;
501 
502 	ret = i2c_init_transfer(i2c_bus, chip, addr, alen);
503 	if (ret < 0)
504 		return ret;
505 
506 	ret = i2c_write_data(i2c_bus, chip, buf, len);
507 
508 	i2c_imx_stop(i2c_bus);
509 
510 	return ret;
511 }
512 
513 #if !defined(I2C2_BASE_ADDR)
514 #define I2C2_BASE_ADDR	0
515 #endif
516 
517 #if !defined(I2C3_BASE_ADDR)
518 #define I2C3_BASE_ADDR	0
519 #endif
520 
521 #if !defined(I2C4_BASE_ADDR)
522 #define I2C4_BASE_ADDR	0
523 #endif
524 
525 static struct mxc_i2c_bus mxc_i2c_buses[] = {
526 #if defined(CONFIG_LS102XA) || defined(CONFIG_VF610) || \
527 	defined(CONFIG_FSL_LAYERSCAPE)
528 	{ 0, I2C1_BASE_ADDR, I2C_QUIRK_FLAG },
529 	{ 1, I2C2_BASE_ADDR, I2C_QUIRK_FLAG },
530 	{ 2, I2C3_BASE_ADDR, I2C_QUIRK_FLAG },
531 	{ 3, I2C4_BASE_ADDR, I2C_QUIRK_FLAG },
532 #else
533 	{ 0, I2C1_BASE_ADDR, 0 },
534 	{ 1, I2C2_BASE_ADDR, 0 },
535 	{ 2, I2C3_BASE_ADDR, 0 },
536 	{ 3, I2C4_BASE_ADDR, 0 },
537 #endif
538 };
539 
540 struct mxc_i2c_bus *i2c_get_base(struct i2c_adapter *adap)
541 {
542 	return &mxc_i2c_buses[adap->hwadapnr];
543 }
544 
545 static int mxc_i2c_read(struct i2c_adapter *adap, uint8_t chip,
546 				uint addr, int alen, uint8_t *buffer,
547 				int len)
548 {
549 	return bus_i2c_read(i2c_get_base(adap), chip, addr, alen, buffer, len);
550 }
551 
552 static int mxc_i2c_write(struct i2c_adapter *adap, uint8_t chip,
553 				uint addr, int alen, uint8_t *buffer,
554 				int len)
555 {
556 	return bus_i2c_write(i2c_get_base(adap), chip, addr, alen, buffer, len);
557 }
558 
559 /*
560  * Test if a chip at a given address responds (probe the chip)
561  */
562 static int mxc_i2c_probe(struct i2c_adapter *adap, uint8_t chip)
563 {
564 	return bus_i2c_write(i2c_get_base(adap), chip, 0, 0, NULL, 0);
565 }
566 
567 int __enable_i2c_clk(unsigned char enable, unsigned i2c_num)
568 {
569 	return 1;
570 }
571 int enable_i2c_clk(unsigned char enable, unsigned i2c_num)
572 	__attribute__((weak, alias("__enable_i2c_clk")));
573 
574 void bus_i2c_init(int index, int speed, int unused,
575 		  int (*idle_bus_fn)(void *p), void *idle_bus_data)
576 {
577 	int ret;
578 
579 	if (index >= ARRAY_SIZE(mxc_i2c_buses)) {
580 		debug("Error i2c index\n");
581 		return;
582 	}
583 
584 	/*
585 	 * Warning: Be careful to allow the assignment to a static
586 	 * variable here. This function could be called while U-Boot is
587 	 * still running in flash memory. So such assignment is equal
588 	 * to write data to flash without erasing.
589 	 */
590 	if (idle_bus_fn)
591 		mxc_i2c_buses[index].idle_bus_fn = idle_bus_fn;
592 	if (idle_bus_data)
593 		mxc_i2c_buses[index].idle_bus_data = idle_bus_data;
594 
595 	ret = enable_i2c_clk(1, index);
596 	if (ret < 0) {
597 		debug("I2C-%d clk fail to enable.\n", index);
598 		return;
599 	}
600 
601 	bus_i2c_set_bus_speed(&mxc_i2c_buses[index], speed);
602 }
603 
604 /*
605  * Init I2C Bus
606  */
607 static void mxc_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr)
608 {
609 	bus_i2c_init(adap->hwadapnr, speed, slaveaddr, NULL, NULL);
610 }
611 
612 /*
613  * Set I2C Speed
614  */
615 static u32 mxc_i2c_set_bus_speed(struct i2c_adapter *adap, uint speed)
616 {
617 	return bus_i2c_set_bus_speed(i2c_get_base(adap), speed);
618 }
619 
620 /*
621  * Register mxc i2c adapters
622  */
623 #ifdef CONFIG_SYS_I2C_MXC_I2C1
624 U_BOOT_I2C_ADAP_COMPLETE(mxc0, mxc_i2c_init, mxc_i2c_probe,
625 			 mxc_i2c_read, mxc_i2c_write,
626 			 mxc_i2c_set_bus_speed,
627 			 CONFIG_SYS_MXC_I2C1_SPEED,
628 			 CONFIG_SYS_MXC_I2C1_SLAVE, 0)
629 #endif
630 
631 #ifdef CONFIG_SYS_I2C_MXC_I2C2
632 U_BOOT_I2C_ADAP_COMPLETE(mxc1, mxc_i2c_init, mxc_i2c_probe,
633 			 mxc_i2c_read, mxc_i2c_write,
634 			 mxc_i2c_set_bus_speed,
635 			 CONFIG_SYS_MXC_I2C2_SPEED,
636 			 CONFIG_SYS_MXC_I2C2_SLAVE, 1)
637 #endif
638 
639 #ifdef CONFIG_SYS_I2C_MXC_I2C3
640 U_BOOT_I2C_ADAP_COMPLETE(mxc2, mxc_i2c_init, mxc_i2c_probe,
641 			 mxc_i2c_read, mxc_i2c_write,
642 			 mxc_i2c_set_bus_speed,
643 			 CONFIG_SYS_MXC_I2C3_SPEED,
644 			 CONFIG_SYS_MXC_I2C3_SLAVE, 2)
645 #endif
646 
647 #ifdef CONFIG_SYS_I2C_MXC_I2C4
648 U_BOOT_I2C_ADAP_COMPLETE(mxc3, mxc_i2c_init, mxc_i2c_probe,
649 			 mxc_i2c_read, mxc_i2c_write,
650 			 mxc_i2c_set_bus_speed,
651 			 CONFIG_SYS_MXC_I2C4_SPEED,
652 			 CONFIG_SYS_MXC_I2C4_SLAVE, 3)
653 #endif
654 
655 #else
656 
657 static int mxc_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
658 {
659 	struct mxc_i2c_bus *i2c_bus = dev_get_priv(bus);
660 
661 	return bus_i2c_set_bus_speed(i2c_bus, speed);
662 }
663 
664 static int mxc_i2c_probe(struct udevice *bus)
665 {
666 	struct mxc_i2c_bus *i2c_bus = dev_get_priv(bus);
667 	fdt_addr_t addr;
668 	int ret;
669 
670 	i2c_bus->driver_data = dev_get_driver_data(bus);
671 
672 	addr = dev_get_addr(bus);
673 	if (addr == FDT_ADDR_T_NONE)
674 		return -ENODEV;
675 
676 	i2c_bus->base = addr;
677 	i2c_bus->index = bus->seq;
678 
679 	/* Enable clk */
680 	ret = enable_i2c_clk(1, bus->seq);
681 	if (ret < 0)
682 		return ret;
683 
684 	ret = i2c_idle_bus(i2c_bus);
685 	if (ret < 0) {
686 		/* Disable clk */
687 		enable_i2c_clk(0, bus->seq);
688 		return ret;
689 	}
690 
691 	/*
692 	 * Pinmux settings are in board file now, until pinmux is supported,
693 	 * we can set pinmux here in probe function.
694 	 */
695 
696 	debug("i2c : controller bus %d at %lu , speed %d: ",
697 	      bus->seq, i2c_bus->base,
698 	      i2c_bus->speed);
699 
700 	return 0;
701 }
702 
703 static int mxc_i2c_probe_chip(struct udevice *bus, u32 chip_addr,
704 			      u32 chip_flags)
705 {
706 	int ret;
707 	struct mxc_i2c_bus *i2c_bus = dev_get_priv(bus);
708 
709 	ret = i2c_init_transfer(i2c_bus, chip_addr, 0, 0);
710 	if (ret < 0) {
711 		debug("%s failed, ret = %d\n", __func__, ret);
712 		return ret;
713 	}
714 
715 	i2c_imx_stop(i2c_bus);
716 
717 	return 0;
718 }
719 
720 static int mxc_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
721 {
722 	struct mxc_i2c_bus *i2c_bus = dev_get_priv(bus);
723 	int ret = 0;
724 	ulong base = i2c_bus->base;
725 	int reg_shift = i2c_bus->driver_data & I2C_QUIRK_FLAG ?
726 		VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
727 
728 	/*
729 	 * Here the 3rd parameter addr and the 4th one alen are set to 0,
730 	 * because here we only want to send out chip address. The register
731 	 * address is wrapped in msg.
732 	 */
733 	ret = i2c_init_transfer(i2c_bus, msg->addr, 0, 0);
734 	if (ret < 0) {
735 		debug("i2c_init_transfer error: %d\n", ret);
736 		return ret;
737 	}
738 
739 	for (; nmsgs > 0; nmsgs--, msg++) {
740 		bool next_is_read = nmsgs > 1 && (msg[1].flags & I2C_M_RD);
741 		debug("i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
742 		if (msg->flags & I2C_M_RD)
743 			ret = i2c_read_data(i2c_bus, msg->addr, msg->buf,
744 					    msg->len);
745 		else {
746 			ret = i2c_write_data(i2c_bus, msg->addr, msg->buf,
747 					     msg->len);
748 			if (ret)
749 				break;
750 			if (next_is_read) {
751 				/* Reuse ret */
752 				ret = readb(base + (I2CR << reg_shift));
753 				ret |= I2CR_RSTA;
754 				writeb(ret, base + (I2CR << reg_shift));
755 
756 				ret = tx_byte(i2c_bus, (msg->addr << 1) | 1);
757 				if (ret < 0) {
758 					i2c_imx_stop(i2c_bus);
759 					break;
760 				}
761 			}
762 		}
763 	}
764 
765 	if (ret)
766 		debug("i2c_write: error sending\n");
767 
768 	i2c_imx_stop(i2c_bus);
769 
770 	return ret;
771 }
772 
773 static const struct dm_i2c_ops mxc_i2c_ops = {
774 	.xfer		= mxc_i2c_xfer,
775 	.probe_chip	= mxc_i2c_probe_chip,
776 	.set_bus_speed	= mxc_i2c_set_bus_speed,
777 };
778 
779 static const struct udevice_id mxc_i2c_ids[] = {
780 	{ .compatible = "fsl,imx21-i2c", },
781 	{ .compatible = "fsl,vf610-i2c", .data = I2C_QUIRK_FLAG, },
782 	{}
783 };
784 
785 U_BOOT_DRIVER(i2c_mxc) = {
786 	.name = "i2c_mxc",
787 	.id = UCLASS_I2C,
788 	.of_match = mxc_i2c_ids,
789 	.probe = mxc_i2c_probe,
790 	.priv_auto_alloc_size = sizeof(struct mxc_i2c_bus),
791 	.ops = &mxc_i2c_ops,
792 };
793 #endif
794