xref: /openbmc/u-boot/drivers/i2c/mvtwsi.c (revision 2399e401)
1 /*
2  * Driver for the TWSI (i2c) controller found on the Marvell
3  * orion5x and kirkwood SoC families.
4  *
5  * Author: Albert Aribaud <albert.u.boot@aribaud.net>
6  * Copyright (c) 2010 Albert Aribaud.
7  *
8  * SPDX-License-Identifier:	GPL-2.0+
9  */
10 
11 #include <common.h>
12 #include <i2c.h>
13 #include <linux/errno.h>
14 #include <asm/io.h>
15 #include <linux/compat.h>
16 #ifdef CONFIG_DM_I2C
17 #include <dm.h>
18 #endif
19 
20 DECLARE_GLOBAL_DATA_PTR;
21 
22 /*
23  * Include a file that will provide CONFIG_I2C_MVTWSI_BASE*, and possibly other
24  * settings
25  */
26 
27 #ifndef CONFIG_DM_I2C
28 #if defined(CONFIG_ORION5X)
29 #include <asm/arch/orion5x.h>
30 #elif (defined(CONFIG_KIRKWOOD) || defined(CONFIG_ARCH_MVEBU))
31 #include <asm/arch/soc.h>
32 #elif defined(CONFIG_ARCH_SUNXI)
33 #include <asm/arch/i2c.h>
34 #else
35 #error Driver mvtwsi not supported by SoC or board
36 #endif
37 #endif /* CONFIG_DM_I2C */
38 
39 /*
40  * TWSI register structure
41  */
42 
43 #ifdef CONFIG_ARCH_SUNXI
44 
45 struct  mvtwsi_registers {
46 	u32 slave_address;
47 	u32 xtnd_slave_addr;
48 	u32 data;
49 	u32 control;
50 	u32 status;
51 	u32 baudrate;
52 	u32 soft_reset;
53 };
54 
55 #else
56 
57 struct  mvtwsi_registers {
58 	u32 slave_address;
59 	u32 data;
60 	u32 control;
61 	union {
62 		u32 status;	/* When reading */
63 		u32 baudrate;	/* When writing */
64 	};
65 	u32 xtnd_slave_addr;
66 	u32 reserved[2];
67 	u32 soft_reset;
68 };
69 
70 #endif
71 
72 #ifdef CONFIG_DM_I2C
73 struct mvtwsi_i2c_dev {
74 	/* TWSI Register base for the device */
75 	struct mvtwsi_registers *base;
76 	/* Number of the device (determined from cell-index property) */
77 	int index;
78 	/* The I2C slave address for the device */
79 	u8 slaveadd;
80 	/* The configured I2C speed in Hz */
81 	uint speed;
82 	/* The current length of a clock period (depending on speed) */
83 	uint tick;
84 };
85 #endif /* CONFIG_DM_I2C */
86 
87 /*
88  * enum mvtwsi_ctrl_register_fields - Bit masks for flags in the control
89  * register
90  */
91 enum mvtwsi_ctrl_register_fields {
92 	/* Acknowledge bit */
93 	MVTWSI_CONTROL_ACK	= 0x00000004,
94 	/* Interrupt flag */
95 	MVTWSI_CONTROL_IFLG	= 0x00000008,
96 	/* Stop bit */
97 	MVTWSI_CONTROL_STOP	= 0x00000010,
98 	/* Start bit */
99 	MVTWSI_CONTROL_START	= 0x00000020,
100 	/* I2C enable */
101 	MVTWSI_CONTROL_TWSIEN	= 0x00000040,
102 	/* Interrupt enable */
103 	MVTWSI_CONTROL_INTEN	= 0x00000080,
104 };
105 
106 /*
107  * On sun6i and newer, IFLG is a write-clear bit, which is cleared by writing 1;
108  * on other platforms, it is a normal r/w bit, which is cleared by writing 0.
109  */
110 
111 #ifdef CONFIG_SUNXI_GEN_SUN6I
112 #define	MVTWSI_CONTROL_CLEAR_IFLG	0x00000008
113 #else
114 #define	MVTWSI_CONTROL_CLEAR_IFLG	0x00000000
115 #endif
116 
117 /*
118  * enum mvstwsi_status_values - Possible values of I2C controller's status
119  * register
120  *
121  * Only those statuses expected in normal master operation on
122  * non-10-bit-address devices are specified.
123  *
124  * Every status that's unexpected during normal operation (bus errors,
125  * arbitration losses, missing ACKs...) is passed back to the caller as an error
126  * code.
127  */
128 enum mvstwsi_status_values {
129 	/* START condition transmitted */
130 	MVTWSI_STATUS_START		= 0x08,
131 	/* Repeated START condition transmitted */
132 	MVTWSI_STATUS_REPEATED_START	= 0x10,
133 	/* Address + write bit transmitted, ACK received */
134 	MVTWSI_STATUS_ADDR_W_ACK	= 0x18,
135 	/* Data transmitted, ACK received */
136 	MVTWSI_STATUS_DATA_W_ACK	= 0x28,
137 	/* Address + read bit transmitted, ACK received */
138 	MVTWSI_STATUS_ADDR_R_ACK	= 0x40,
139 	/* Address + read bit transmitted, ACK not received */
140 	MVTWSI_STATUS_ADDR_R_NAK	= 0x48,
141 	/* Data received, ACK transmitted */
142 	MVTWSI_STATUS_DATA_R_ACK	= 0x50,
143 	/* Data received, ACK not transmitted */
144 	MVTWSI_STATUS_DATA_R_NAK	= 0x58,
145 	/* No relevant status */
146 	MVTWSI_STATUS_IDLE		= 0xF8,
147 };
148 
149 /*
150  * enum mvstwsi_ack_flags - Determine whether a read byte should be
151  * acknowledged or not.
152  */
153 enum mvtwsi_ack_flags {
154 	/* Send NAK after received byte */
155 	MVTWSI_READ_NAK = 0,
156 	/* Send ACK after received byte */
157 	MVTWSI_READ_ACK = 1,
158 };
159 
160 /*
161  * calc_tick() - Calculate the duration of a clock cycle from the I2C speed
162  *
163  * @speed:	The speed in Hz to calculate the clock cycle duration for.
164  * @return The duration of a clock cycle in ns.
165  */
166 inline uint calc_tick(uint speed)
167 {
168 	/* One tick = the duration of a period at the specified speed in ns (we
169 	 * add 100 ns to be on the safe side) */
170 	return (1000000000u / speed) + 100;
171 }
172 
173 #ifndef CONFIG_DM_I2C
174 
175 /*
176  * twsi_get_base() - Get controller register base for specified adapter
177  *
178  * @adap:	Adapter to get the register base for.
179  * @return Register base for the specified adapter.
180  */
181 static struct mvtwsi_registers *twsi_get_base(struct i2c_adapter *adap)
182 {
183 	switch (adap->hwadapnr) {
184 #ifdef CONFIG_I2C_MVTWSI_BASE0
185 	case 0:
186 		return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE0;
187 #endif
188 #ifdef CONFIG_I2C_MVTWSI_BASE1
189 	case 1:
190 		return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE1;
191 #endif
192 #ifdef CONFIG_I2C_MVTWSI_BASE2
193 	case 2:
194 		return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE2;
195 #endif
196 #ifdef CONFIG_I2C_MVTWSI_BASE3
197 	case 3:
198 		return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE3;
199 #endif
200 #ifdef CONFIG_I2C_MVTWSI_BASE4
201 	case 4:
202 		return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE4;
203 #endif
204 #ifdef CONFIG_I2C_MVTWSI_BASE5
205 	case 5:
206 		return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE5;
207 #endif
208 	default:
209 		printf("Missing mvtwsi controller %d base\n", adap->hwadapnr);
210 		break;
211 	}
212 
213 	return NULL;
214 }
215 #endif
216 
217 /*
218  * enum mvtwsi_error_class - types of I2C errors
219  */
220 enum mvtwsi_error_class {
221 	/* The controller returned a different status than expected */
222 	MVTWSI_ERROR_WRONG_STATUS       = 0x01,
223 	/* The controller timed out */
224 	MVTWSI_ERROR_TIMEOUT            = 0x02,
225 };
226 
227 /*
228  * mvtwsi_error() - Build I2C return code from error information
229  *
230  * For debugging purposes, this function packs some information of an occurred
231  * error into a return code. These error codes are returned from I2C API
232  * functions (i2c_{read,write}, dm_i2c_{read,write}, etc.).
233  *
234  * @ec:		The error class of the error (enum mvtwsi_error_class).
235  * @lc:		The last value of the control register.
236  * @ls:		The last value of the status register.
237  * @es:		The expected value of the status register.
238  * @return The generated error code.
239  */
240 inline uint mvtwsi_error(uint ec, uint lc, uint ls, uint es)
241 {
242 	return ((ec << 24) & 0xFF000000)
243 	       | ((lc << 16) & 0x00FF0000)
244 	       | ((ls << 8) & 0x0000FF00)
245 	       | (es & 0xFF);
246 }
247 
248 /*
249  * twsi_wait() - Wait for I2C bus interrupt flag and check status, or time out.
250  *
251  * @return Zero if status is as expected, or a non-zero code if either a time
252  *	   out occurred, or the status was not the expected one.
253  */
254 static int twsi_wait(struct mvtwsi_registers *twsi, int expected_status,
255 		     uint tick)
256 {
257 	int control, status;
258 	int timeout = 1000;
259 
260 	do {
261 		control = readl(&twsi->control);
262 		if (control & MVTWSI_CONTROL_IFLG) {
263 			status = readl(&twsi->status);
264 			if (status == expected_status)
265 				return 0;
266 			else
267 				return mvtwsi_error(
268 					MVTWSI_ERROR_WRONG_STATUS,
269 					control, status, expected_status);
270 		}
271 		ndelay(tick); /* One clock cycle */
272 	} while (timeout--);
273 	status = readl(&twsi->status);
274 	return mvtwsi_error(MVTWSI_ERROR_TIMEOUT, control, status,
275 			    expected_status);
276 }
277 
278 /*
279  * twsi_start() - Assert a START condition on the bus.
280  *
281  * This function is used in both single I2C transactions and inside
282  * back-to-back transactions (repeated starts).
283  *
284  * @twsi:		The MVTWSI register structure to use.
285  * @expected_status:	The I2C bus status expected to be asserted after the
286  *			operation completion.
287  * @tick:		The duration of a clock cycle at the current I2C speed.
288  * @return Zero if status is as expected, or a non-zero code if either a time
289  *	   out occurred or the status was not the expected one.
290  */
291 static int twsi_start(struct mvtwsi_registers *twsi, int expected_status,
292 		      uint tick)
293 {
294 	/* Assert START */
295 	writel(MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_START |
296 	       MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
297 	/* Wait for controller to process START */
298 	return twsi_wait(twsi, expected_status, tick);
299 }
300 
301 /*
302  * twsi_send() - Send a byte on the I2C bus.
303  *
304  * The byte may be part of an address byte or data.
305  *
306  * @twsi:		The MVTWSI register structure to use.
307  * @byte:		The byte to send.
308  * @expected_status:	The I2C bus status expected to be asserted after the
309  *			operation completion.
310  * @tick:		The duration of a clock cycle at the current I2C speed.
311  * @return Zero if status is as expected, or a non-zero code if either a time
312  *	   out occurred or the status was not the expected one.
313  */
314 static int twsi_send(struct mvtwsi_registers *twsi, u8 byte,
315 		     int expected_status, uint tick)
316 {
317 	/* Write byte to data register for sending */
318 	writel(byte, &twsi->data);
319 	/* Clear any pending interrupt -- that will cause sending */
320 	writel(MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_CLEAR_IFLG,
321 	       &twsi->control);
322 	/* Wait for controller to receive byte, and check ACK */
323 	return twsi_wait(twsi, expected_status, tick);
324 }
325 
326 /*
327  * twsi_recv() - Receive a byte on the I2C bus.
328  *
329  * The static variable mvtwsi_control_flags controls whether we ack or nak.
330  *
331  * @twsi:		The MVTWSI register structure to use.
332  * @byte:		The byte to send.
333  * @ack_flag:		Flag that determines whether the received byte should
334  *			be acknowledged by the controller or not (sent ACK/NAK).
335  * @tick:		The duration of a clock cycle at the current I2C speed.
336  * @return Zero if status is as expected, or a non-zero code if either a time
337  *	   out occurred or the status was not the expected one.
338  */
339 static int twsi_recv(struct mvtwsi_registers *twsi, u8 *byte, int ack_flag,
340 		     uint tick)
341 {
342 	int expected_status, status, control;
343 
344 	/* Compute expected status based on passed ACK flag */
345 	expected_status = ack_flag ? MVTWSI_STATUS_DATA_R_ACK :
346 			  MVTWSI_STATUS_DATA_R_NAK;
347 	/* Acknowledge *previous state*, and launch receive */
348 	control = MVTWSI_CONTROL_TWSIEN;
349 	control |= ack_flag == MVTWSI_READ_ACK ? MVTWSI_CONTROL_ACK : 0;
350 	writel(control | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
351 	/* Wait for controller to receive byte, and assert ACK or NAK */
352 	status = twsi_wait(twsi, expected_status, tick);
353 	/* If we did receive the expected byte, store it */
354 	if (status == 0)
355 		*byte = readl(&twsi->data);
356 	return status;
357 }
358 
359 /*
360  * twsi_stop() - Assert a STOP condition on the bus.
361  *
362  * This function is also used to force the bus back to idle state (SDA =
363  * SCL = 1).
364  *
365  * @twsi:	The MVTWSI register structure to use.
366  * @tick:	The duration of a clock cycle at the current I2C speed.
367  * @return Zero if the operation succeeded, or a non-zero code if a time out
368  *	   occurred.
369  */
370 static int twsi_stop(struct mvtwsi_registers *twsi, uint tick)
371 {
372 	int control, stop_status;
373 	int status = 0;
374 	int timeout = 1000;
375 
376 	/* Assert STOP */
377 	control = MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_STOP;
378 	writel(control | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
379 	/* Wait for IDLE; IFLG won't rise, so we can't use twsi_wait() */
380 	do {
381 		stop_status = readl(&twsi->status);
382 		if (stop_status == MVTWSI_STATUS_IDLE)
383 			break;
384 		ndelay(tick); /* One clock cycle */
385 	} while (timeout--);
386 	control = readl(&twsi->control);
387 	if (stop_status != MVTWSI_STATUS_IDLE)
388 		status = mvtwsi_error(MVTWSI_ERROR_TIMEOUT,
389 				      control, status, MVTWSI_STATUS_IDLE);
390 	return status;
391 }
392 
393 /*
394  * twsi_calc_freq() - Compute I2C frequency depending on m and n parameters.
395  *
396  * @n:		Parameter 'n' for the frequency calculation algorithm.
397  * @m:		Parameter 'm' for the frequency calculation algorithm.
398  * @return The I2C frequency corresponding to the passed m and n parameters.
399  */
400 static uint twsi_calc_freq(const int n, const int m)
401 {
402 #ifdef CONFIG_ARCH_SUNXI
403 	return CONFIG_SYS_TCLK / (10 * (m + 1) * (1 << n));
404 #else
405 	return CONFIG_SYS_TCLK / (10 * (m + 1) * (2 << n));
406 #endif
407 }
408 
409 /*
410  * twsi_reset() - Reset the I2C controller.
411  *
412  * Resetting the controller also resets the baud rate and slave address, hence
413  * they must be re-established after the reset.
414  *
415  * @twsi:	The MVTWSI register structure to use.
416  */
417 static void twsi_reset(struct mvtwsi_registers *twsi)
418 {
419 	/* Reset controller */
420 	writel(0, &twsi->soft_reset);
421 	/* Wait 2 ms -- this is what the Marvell LSP does */
422 	udelay(20000);
423 }
424 
425 /*
426  * __twsi_i2c_set_bus_speed() - Set the speed of the I2C controller.
427  *
428  * This function sets baud rate to the highest possible value that does not
429  * exceed the requested rate.
430  *
431  * @twsi:		The MVTWSI register structure to use.
432  * @requested_speed:	The desired frequency the controller should run at
433  *			in Hz.
434  * @return The actual frequency the controller was configured to.
435  */
436 static uint __twsi_i2c_set_bus_speed(struct mvtwsi_registers *twsi,
437 				     uint requested_speed)
438 {
439 	uint tmp_speed, highest_speed, n, m;
440 	uint baud = 0x44; /* Baud rate after controller reset */
441 
442 	highest_speed = 0;
443 	/* Successively try m, n combinations, and use the combination
444 	 * resulting in the largest speed that's not above the requested
445 	 * speed */
446 	for (n = 0; n < 8; n++) {
447 		for (m = 0; m < 16; m++) {
448 			tmp_speed = twsi_calc_freq(n, m);
449 			if ((tmp_speed <= requested_speed) &&
450 			    (tmp_speed > highest_speed)) {
451 				highest_speed = tmp_speed;
452 				baud = (m << 3) | n;
453 			}
454 		}
455 	}
456 	writel(baud, &twsi->baudrate);
457 
458 	/* Wait for controller for one tick */
459 #ifdef CONFIG_DM_I2C
460 	ndelay(calc_tick(highest_speed));
461 #else
462 	ndelay(10000);
463 #endif
464 	return highest_speed;
465 }
466 
467 /*
468  * __twsi_i2c_init() - Initialize the I2C controller.
469  *
470  * @twsi:		The MVTWSI register structure to use.
471  * @speed:		The initial frequency the controller should run at
472  *			in Hz.
473  * @slaveadd:		The I2C address to be set for the I2C master.
474  * @actual_speed:	A output parameter that receives the actual frequency
475  *			in Hz the controller was set to by the function.
476  * @return Zero if the operation succeeded, or a non-zero code if a time out
477  *	   occurred.
478  */
479 static void __twsi_i2c_init(struct mvtwsi_registers *twsi, int speed,
480 			    int slaveadd, uint *actual_speed)
481 {
482 	/* Reset controller */
483 	twsi_reset(twsi);
484 	/* Set speed */
485 	*actual_speed = __twsi_i2c_set_bus_speed(twsi, speed);
486 	/* Set slave address; even though we don't use it */
487 	writel(slaveadd, &twsi->slave_address);
488 	writel(0, &twsi->xtnd_slave_addr);
489 	/* Assert STOP, but don't care for the result */
490 #ifdef CONFIG_DM_I2C
491 	(void) twsi_stop(twsi, calc_tick(*actual_speed));
492 #else
493 	(void) twsi_stop(twsi, 10000);
494 #endif
495 }
496 
497 /*
498  * i2c_begin() - Start a I2C transaction.
499  *
500  * Begin a I2C transaction with a given expected start status and chip address.
501  * A START is asserted, and the address byte is sent to the I2C controller. The
502  * expected address status will be derived from the direction bit (bit 0) of
503  * the address byte.
504  *
505  * @twsi:			The MVTWSI register structure to use.
506  * @expected_start_status:	The I2C status the controller is expected to
507  *				assert after the address byte was sent.
508  * @addr:			The address byte to be sent.
509  * @tick:			The duration of a clock cycle at the current
510  *				I2C speed.
511  * @return Zero if the operation succeeded, or a non-zero code if a time out or
512  *	   unexpected I2C status occurred.
513  */
514 static int i2c_begin(struct mvtwsi_registers *twsi, int expected_start_status,
515 		     u8 addr, uint tick)
516 {
517 	int status, expected_addr_status;
518 
519 	/* Compute the expected address status from the direction bit in
520 	 * the address byte */
521 	if (addr & 1) /* Reading */
522 		expected_addr_status = MVTWSI_STATUS_ADDR_R_ACK;
523 	else /* Writing */
524 		expected_addr_status = MVTWSI_STATUS_ADDR_W_ACK;
525 	/* Assert START */
526 	status = twsi_start(twsi, expected_start_status, tick);
527 	/* Send out the address if the start went well */
528 	if (status == 0)
529 		status = twsi_send(twsi, addr, expected_addr_status, tick);
530 	/* Return 0, or the status of the first failure */
531 	return status;
532 }
533 
534 /*
535  * __twsi_i2c_probe_chip() - Probe the given I2C chip address.
536  *
537  * This function begins a I2C read transaction, does a dummy read and NAKs; if
538  * the procedure succeeds, the chip is considered to be present.
539  *
540  * @twsi:	The MVTWSI register structure to use.
541  * @chip:	The chip address to probe.
542  * @tick:	The duration of a clock cycle at the current I2C speed.
543  * @return Zero if the operation succeeded, or a non-zero code if a time out or
544  *	   unexpected I2C status occurred.
545  */
546 static int __twsi_i2c_probe_chip(struct mvtwsi_registers *twsi, uchar chip,
547 				 uint tick)
548 {
549 	u8 dummy_byte;
550 	int status;
551 
552 	/* Begin i2c read */
553 	status = i2c_begin(twsi, MVTWSI_STATUS_START, (chip << 1) | 1, tick);
554 	/* Dummy read was accepted: receive byte, but NAK it. */
555 	if (status == 0)
556 		status = twsi_recv(twsi, &dummy_byte, MVTWSI_READ_NAK, tick);
557 	/* Stop transaction */
558 	twsi_stop(twsi, tick);
559 	/* Return 0, or the status of the first failure */
560 	return status;
561 }
562 
563 /*
564  * __twsi_i2c_read() - Read data from a I2C chip.
565  *
566  * This function begins a I2C write transaction, and transmits the address
567  * bytes; then begins a I2C read transaction, and receives the data bytes.
568  *
569  * NOTE: Some devices want a stop right before the second start, while some
570  * will choke if it is there. Since deciding this is not yet supported in
571  * higher level APIs, we need to make a decision here, and for the moment that
572  * will be a repeated start without a preceding stop.
573  *
574  * @twsi:	The MVTWSI register structure to use.
575  * @chip:	The chip address to read from.
576  * @addr:	The address bytes to send.
577  * @alen:	The length of the address bytes in bytes.
578  * @data:	The buffer to receive the data read from the chip (has to have
579  *		a size of at least 'length' bytes).
580  * @length:	The amount of data to be read from the chip in bytes.
581  * @tick:	The duration of a clock cycle at the current I2C speed.
582  * @return Zero if the operation succeeded, or a non-zero code if a time out or
583  *	   unexpected I2C status occurred.
584  */
585 static int __twsi_i2c_read(struct mvtwsi_registers *twsi, uchar chip,
586 			   u8 *addr, int alen, uchar *data, int length,
587 			   uint tick)
588 {
589 	int status = 0;
590 	int stop_status;
591 	int expected_start = MVTWSI_STATUS_START;
592 
593 	if (alen > 0) {
594 		/* Begin i2c write to send the address bytes */
595 		status = i2c_begin(twsi, expected_start, (chip << 1), tick);
596 		/* Send address bytes */
597 		while ((status == 0) && alen--)
598 			status = twsi_send(twsi, addr[alen],
599 					   MVTWSI_STATUS_DATA_W_ACK, tick);
600 		/* Send repeated STARTs after the initial START */
601 		expected_start = MVTWSI_STATUS_REPEATED_START;
602 	}
603 	/* Begin i2c read to receive data bytes */
604 	if (status == 0)
605 		status = i2c_begin(twsi, expected_start, (chip << 1) | 1, tick);
606 	/* Receive actual data bytes; set NAK if we if we have nothing more to
607 	 * read */
608 	while ((status == 0) && length--)
609 		status = twsi_recv(twsi, data++,
610 				   length > 0 ?
611 				   MVTWSI_READ_ACK : MVTWSI_READ_NAK, tick);
612 	/* Stop transaction */
613 	stop_status = twsi_stop(twsi, tick);
614 	/* Return 0, or the status of the first failure */
615 	return status != 0 ? status : stop_status;
616 }
617 
618 /*
619  * __twsi_i2c_write() - Send data to a I2C chip.
620  *
621  * This function begins a I2C write transaction, and transmits the address
622  * bytes; then begins a new I2C write transaction, and sends the data bytes.
623  *
624  * @twsi:	The MVTWSI register structure to use.
625  * @chip:	The chip address to read from.
626  * @addr:	The address bytes to send.
627  * @alen:	The length of the address bytes in bytes.
628  * @data:	The buffer containing the data to be sent to the chip.
629  * @length:	The length of data to be sent to the chip in bytes.
630  * @tick:	The duration of a clock cycle at the current I2C speed.
631  * @return Zero if the operation succeeded, or a non-zero code if a time out or
632  *	   unexpected I2C status occurred.
633  */
634 static int __twsi_i2c_write(struct mvtwsi_registers *twsi, uchar chip,
635 			    u8 *addr, int alen, uchar *data, int length,
636 			    uint tick)
637 {
638 	int status, stop_status;
639 
640 	/* Begin i2c write to send first the address bytes, then the
641 	 * data bytes */
642 	status = i2c_begin(twsi, MVTWSI_STATUS_START, (chip << 1), tick);
643 	/* Send address bytes */
644 	while ((status == 0) && (alen-- > 0))
645 		status = twsi_send(twsi, addr[alen], MVTWSI_STATUS_DATA_W_ACK,
646 				   tick);
647 	/* Send data bytes */
648 	while ((status == 0) && (length-- > 0))
649 		status = twsi_send(twsi, *(data++), MVTWSI_STATUS_DATA_W_ACK,
650 				   tick);
651 	/* Stop transaction */
652 	stop_status = twsi_stop(twsi, tick);
653 	/* Return 0, or the status of the first failure */
654 	return status != 0 ? status : stop_status;
655 }
656 
657 #ifndef CONFIG_DM_I2C
658 static void twsi_i2c_init(struct i2c_adapter *adap, int speed,
659 			  int slaveadd)
660 {
661 	struct mvtwsi_registers *twsi = twsi_get_base(adap);
662 	__twsi_i2c_init(twsi, speed, slaveadd, NULL);
663 }
664 
665 static uint twsi_i2c_set_bus_speed(struct i2c_adapter *adap,
666 				   uint requested_speed)
667 {
668 	struct mvtwsi_registers *twsi = twsi_get_base(adap);
669 	__twsi_i2c_set_bus_speed(twsi, requested_speed);
670 	return 0;
671 }
672 
673 static int twsi_i2c_probe(struct i2c_adapter *adap, uchar chip)
674 {
675 	struct mvtwsi_registers *twsi = twsi_get_base(adap);
676 	return __twsi_i2c_probe_chip(twsi, chip, 10000);
677 }
678 
679 static int twsi_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
680 			 int alen, uchar *data, int length)
681 {
682 	struct mvtwsi_registers *twsi = twsi_get_base(adap);
683 	u8 addr_bytes[4];
684 
685 	addr_bytes[0] = (addr >> 0) & 0xFF;
686 	addr_bytes[1] = (addr >> 8) & 0xFF;
687 	addr_bytes[2] = (addr >> 16) & 0xFF;
688 	addr_bytes[3] = (addr >> 24) & 0xFF;
689 
690 	return __twsi_i2c_read(twsi, chip, addr_bytes, alen, data, length,
691 			       10000);
692 }
693 
694 static int twsi_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
695 			  int alen, uchar *data, int length)
696 {
697 	struct mvtwsi_registers *twsi = twsi_get_base(adap);
698 	u8 addr_bytes[4];
699 
700 	addr_bytes[0] = (addr >> 0) & 0xFF;
701 	addr_bytes[1] = (addr >> 8) & 0xFF;
702 	addr_bytes[2] = (addr >> 16) & 0xFF;
703 	addr_bytes[3] = (addr >> 24) & 0xFF;
704 
705 	return __twsi_i2c_write(twsi, chip, addr_bytes, alen, data, length,
706 				10000);
707 }
708 
709 #ifdef CONFIG_I2C_MVTWSI_BASE0
710 U_BOOT_I2C_ADAP_COMPLETE(twsi0, twsi_i2c_init, twsi_i2c_probe,
711 			 twsi_i2c_read, twsi_i2c_write,
712 			 twsi_i2c_set_bus_speed,
713 			 CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 0)
714 #endif
715 #ifdef CONFIG_I2C_MVTWSI_BASE1
716 U_BOOT_I2C_ADAP_COMPLETE(twsi1, twsi_i2c_init, twsi_i2c_probe,
717 			 twsi_i2c_read, twsi_i2c_write,
718 			 twsi_i2c_set_bus_speed,
719 			 CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 1)
720 
721 #endif
722 #ifdef CONFIG_I2C_MVTWSI_BASE2
723 U_BOOT_I2C_ADAP_COMPLETE(twsi2, twsi_i2c_init, twsi_i2c_probe,
724 			 twsi_i2c_read, twsi_i2c_write,
725 			 twsi_i2c_set_bus_speed,
726 			 CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 2)
727 
728 #endif
729 #ifdef CONFIG_I2C_MVTWSI_BASE3
730 U_BOOT_I2C_ADAP_COMPLETE(twsi3, twsi_i2c_init, twsi_i2c_probe,
731 			 twsi_i2c_read, twsi_i2c_write,
732 			 twsi_i2c_set_bus_speed,
733 			 CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 3)
734 
735 #endif
736 #ifdef CONFIG_I2C_MVTWSI_BASE4
737 U_BOOT_I2C_ADAP_COMPLETE(twsi4, twsi_i2c_init, twsi_i2c_probe,
738 			 twsi_i2c_read, twsi_i2c_write,
739 			 twsi_i2c_set_bus_speed,
740 			 CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 4)
741 
742 #endif
743 #ifdef CONFIG_I2C_MVTWSI_BASE5
744 U_BOOT_I2C_ADAP_COMPLETE(twsi5, twsi_i2c_init, twsi_i2c_probe,
745 			 twsi_i2c_read, twsi_i2c_write,
746 			 twsi_i2c_set_bus_speed,
747 			 CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 5)
748 
749 #endif
750 #else /* CONFIG_DM_I2C */
751 
752 static int mvtwsi_i2c_probe_chip(struct udevice *bus, u32 chip_addr,
753 				 u32 chip_flags)
754 {
755 	struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);
756 	return __twsi_i2c_probe_chip(dev->base, chip_addr, dev->tick);
757 }
758 
759 static int mvtwsi_i2c_set_bus_speed(struct udevice *bus, uint speed)
760 {
761 	struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);
762 
763 	dev->speed = __twsi_i2c_set_bus_speed(dev->base, speed);
764 	dev->tick = calc_tick(dev->speed);
765 
766 	return 0;
767 }
768 
769 static int mvtwsi_i2c_ofdata_to_platdata(struct udevice *bus)
770 {
771 	struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);
772 
773 	dev->base = dev_get_addr_ptr(bus);
774 
775 	if (!dev->base)
776 		return -ENOMEM;
777 
778 	dev->index = fdtdec_get_int(gd->fdt_blob, dev_of_offset(bus),
779 				    "cell-index", -1);
780 	dev->slaveadd = fdtdec_get_int(gd->fdt_blob, dev_of_offset(bus),
781 				       "u-boot,i2c-slave-addr", 0x0);
782 	dev->speed = fdtdec_get_int(gd->fdt_blob, dev_of_offset(bus),
783 				    "clock-frequency", 100000);
784 	return 0;
785 }
786 
787 static int mvtwsi_i2c_probe(struct udevice *bus)
788 {
789 	struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);
790 	uint actual_speed;
791 
792 	__twsi_i2c_init(dev->base, dev->speed, dev->slaveadd, &actual_speed);
793 	dev->speed = actual_speed;
794 	dev->tick = calc_tick(dev->speed);
795 	return 0;
796 }
797 
798 static int mvtwsi_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
799 {
800 	struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);
801 	struct i2c_msg *dmsg, *omsg, dummy;
802 
803 	memset(&dummy, 0, sizeof(struct i2c_msg));
804 
805 	/* We expect either two messages (one with an offset and one with the
806 	 * actual data) or one message (just data or offset/data combined) */
807 	if (nmsgs > 2 || nmsgs == 0) {
808 		debug("%s: Only one or two messages are supported.", __func__);
809 		return -1;
810 	}
811 
812 	omsg = nmsgs == 1 ? &dummy : msg;
813 	dmsg = nmsgs == 1 ? msg : msg + 1;
814 
815 	if (dmsg->flags & I2C_M_RD)
816 		return __twsi_i2c_read(dev->base, dmsg->addr, omsg->buf,
817 				       omsg->len, dmsg->buf, dmsg->len,
818 				       dev->tick);
819 	else
820 		return __twsi_i2c_write(dev->base, dmsg->addr, omsg->buf,
821 					omsg->len, dmsg->buf, dmsg->len,
822 					dev->tick);
823 }
824 
825 static const struct dm_i2c_ops mvtwsi_i2c_ops = {
826 	.xfer		= mvtwsi_i2c_xfer,
827 	.probe_chip	= mvtwsi_i2c_probe_chip,
828 	.set_bus_speed	= mvtwsi_i2c_set_bus_speed,
829 };
830 
831 static const struct udevice_id mvtwsi_i2c_ids[] = {
832 	{ .compatible = "marvell,mv64xxx-i2c", },
833 	{ .compatible = "marvell,mv78230-i2c", },
834 	{ /* sentinel */ }
835 };
836 
837 U_BOOT_DRIVER(i2c_mvtwsi) = {
838 	.name = "i2c_mvtwsi",
839 	.id = UCLASS_I2C,
840 	.of_match = mvtwsi_i2c_ids,
841 	.probe = mvtwsi_i2c_probe,
842 	.ofdata_to_platdata = mvtwsi_i2c_ofdata_to_platdata,
843 	.priv_auto_alloc_size = sizeof(struct mvtwsi_i2c_dev),
844 	.ops = &mvtwsi_i2c_ops,
845 };
846 #endif /* CONFIG_DM_I2C */
847