summaryrefslogtreecommitdiffstats
path: root/drivers/i2c/busses/i2c-nuc900.c
blob: f41502ef3f55086db9f87610b95d2acb07d72434 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
/*
 * linux/drivers/i2c/busses/i2c-nuc900.c
 *
 * Copyright (c) 2010 Nuvoton technology corporation.
 *
 * This driver based on S3C2410 I2C driver of Ben Dooks <ben-Y5A6D6n0/KfQXOPxS62xeg@public.gmane.org>.
 * Written by Wan ZongShun <mcuos.com-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation;version 2 of the License.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>

#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/cpufreq.h>
#include <linux/slab.h>
#include <linux/io.h>

#include <mach/mfp.h>
#include <linux/platform_data/i2c-nuc900.h>

/* nuc900 i2c registers offset */

#define CSR		0x00
#define DIVIDER		0x04
#define CMDR		0x08
#define SWR		0x0C
#define RXR		0x10
#define TXR		0x14

/* nuc900 i2c CSR register bits */

#define IRQEN		0x003
#define I2CBUSY		0x400
#define I2CSTART	0x018
#define IRQFLAG		0x004
#define ARBIT_LOST	0x200
#define SLAVE_ACK	0x800

/* nuc900 i2c CMDR register bits */

#define I2C_CMD_START	0x10
#define I2C_CMD_STOP	0x08
#define I2C_CMD_READ	0x04
#define I2C_CMD_WRITE	0x02
#define I2C_CMD_NACK	0x01

/* i2c controller state */

enum nuc900_i2c_state {
	STATE_IDLE,
	STATE_START,
	STATE_READ,
	STATE_WRITE,
	STATE_STOP
};

/* i2c controller private data */

struct nuc900_i2c {
	spinlock_t		lock;
	wait_queue_head_t	wait;

	struct i2c_msg		*msg;
	unsigned int		msg_num;
	unsigned int		msg_idx;
	unsigned int		msg_ptr;
	unsigned int		irq;

	enum nuc900_i2c_state	state;

	void __iomem		*regs;
	struct clk		*clk;
	struct device		*dev;
	struct resource		*ioarea;
	struct i2c_adapter	adap;
};

/* nuc900_i2c_master_complete
 *
 * complete the message and wake up the caller, using the given return code,
 * or zero to mean ok.
*/

static inline void nuc900_i2c_master_complete(struct nuc900_i2c *i2c, int ret)
{
	dev_dbg(i2c->dev, "master_complete %d\n", ret);

	i2c->msg_ptr = 0;
	i2c->msg = NULL;
	i2c->msg_idx++;
	i2c->msg_num = 0;
	if (ret)
		i2c->msg_idx = ret;

	wake_up(&i2c->wait);
}

/* irq enable/disable functions */

static inline void nuc900_i2c_disable_irq(struct nuc900_i2c *i2c)
{
	unsigned long tmp;

	tmp = readl(i2c->regs + CSR);
	writel(tmp & ~IRQEN, i2c->regs + CSR);
}

static inline void nuc900_i2c_enable_irq(struct nuc900_i2c *i2c)
{
	unsigned long tmp;

	tmp = readl(i2c->regs + CSR);
	writel(tmp | IRQEN, i2c->regs + CSR);
}


/* nuc900_i2c_message_start
 *
 * put the start of a message onto the bus
*/

static void nuc900_i2c_message_start(struct nuc900_i2c *i2c,
				      struct i2c_msg *msg)
{
	unsigned int addr = (msg->addr & 0x7f) << 1;

	if (msg->flags & I2C_M_RD)
		addr |= 0x1;
	writel(addr & 0xff, i2c->regs + TXR);
	writel(I2C_CMD_START | I2C_CMD_WRITE, i2c->regs + CMDR);
}

static inline void nuc900_i2c_stop(struct nuc900_i2c *i2c, int ret)
{

	dev_dbg(i2c->dev, "STOP\n");

	/* stop the transfer */
	i2c->state = STATE_STOP;
	writel(I2C_CMD_STOP, i2c->regs + CMDR);

	nuc900_i2c_master_complete(i2c, ret);
	nuc900_i2c_disable_irq(i2c);
}

/* helper functions to determine the current state in the set of
 * messages we are sending
*/

/* is_lastmsg()
 *
 * returns TRUE if the current message is the last in the set
*/

static inline int is_lastmsg(struct nuc900_i2c *i2c)
{
	return i2c->msg_idx >= (i2c->msg_num - 1);
}

/* is_msglast
 *
 * returns TRUE if we this is the last byte in the current message
*/

static inline int is_msglast(struct nuc900_i2c *i2c)
{
	return i2c->msg_ptr == i2c->msg->len-1;
}

/* is_msgend
 *
 * returns TRUE if we reached the end of the current message
*/

static inline int is_msgend(struct nuc900_i2c *i2c)
{
	return i2c->msg_ptr >= i2c->msg->len;
}

/* i2c_nuc900_irq_nextbyte
 *
 * process an interrupt and work out what to do
 */

static void i2c_nuc900_irq_nextbyte(struct nuc900_i2c *i2c,
							unsigned long iicstat)
{
	unsigned char byte;

	switch (i2c->state) {

	case STATE_IDLE:
		dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __func__);
		break;

	case STATE_STOP:
		dev_err(i2c->dev, "%s: called in STATE_STOP\n", __func__);
		nuc900_i2c_disable_irq(i2c);
		break;

	case STATE_START:
		/* last thing we did was send a start condition on the
		 * bus, or started a new i2c message
		 */

		if (iicstat & SLAVE_ACK &&
		    !(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
			/* ack was not received... */

			dev_dbg(i2c->dev, "ack was not received\n");
			nuc900_i2c_stop(i2c, -ENXIO);
			break;
		}

		if (i2c->msg->flags & I2C_M_RD)
			i2c->state = STATE_READ;
		else
			i2c->state = STATE_WRITE;

		/* terminate the transfer if there is nothing to do
		 * as this is used by the i2c probe to find devices.
		*/

		if (is_lastmsg(i2c) && i2c->msg->len == 0) {
			nuc900_i2c_stop(i2c, 0);
			break;
		}

		if (i2c->state == STATE_READ)
			goto prepare_read;

		/* fall through to the write state, as we will need to
		 * send a byte as well
		*/

	case STATE_WRITE:
		/* we are writing data to the device... check for the
		 * end of the message, and if so, work out what to do
		 */

		if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
			if (iicstat & SLAVE_ACK) {
				dev_dbg(i2c->dev, "WRITE: No Ack\n");

				nuc900_i2c_stop(i2c, -ECONNREFUSED);
				break;
			}
		}

retry_write:

		if (!is_msgend(i2c)) {
			byte = i2c->msg->buf[i2c->msg_ptr++];
			writeb(byte, i2c->regs + TXR);
			writel(I2C_CMD_WRITE, i2c->regs + CMDR);

		} else if (!is_lastmsg(i2c)) {
			/* we need to go to the next i2c message */

			dev_dbg(i2c->dev, "WRITE: Next Message\n");

			i2c->msg_ptr = 0;
			i2c->msg_idx++;
			i2c->msg++;

			/* check to see if we need to do another message */
			if (i2c->msg->flags & I2C_M_NOSTART) {

				if (i2c->msg->flags & I2C_M_RD) {
					/* cannot do this, the controller
					 * forces us to send a new START
					 * when we change direction
					*/

					nuc900_i2c_stop(i2c, -EINVAL);
				}

				goto retry_write;
			} else {
				/* send the new start */
				nuc900_i2c_message_start(i2c, i2c->msg);
				i2c->state = STATE_START;
			}

		} else {
			/* send stop */

			nuc900_i2c_stop(i2c, 0);
		}
		break;

	case STATE_READ:
		/* we have a byte of data in the data register, do
		 * something with it, and then work out wether we are
		 * going to do any more read/write
		 */

		byte = readb(i2c->regs + RXR);
		i2c->msg->buf[i2c->msg_ptr++] = byte;

prepare_read:
		if (is_msglast(i2c)) {
			/* last byte of buffer */

			if (is_lastmsg(i2c))
				writel(I2C_CMD_READ | I2C_CMD_NACK,
							i2c->regs + CMDR);

		} else if (is_msgend(i2c)) {
			/* ok, we've read the entire buffer, see if there
			 * is anything else we need to do
			*/

			if (is_lastmsg(i2c)) {
				/* last message, send stop and complete */
				dev_dbg(i2c->dev, "READ: Send Stop\n");

				nuc900_i2c_stop(i2c, 0);
			} else {
				/* go to the next transfer */
				dev_dbg(i2c->dev, "READ: Next Transfer\n");

				i2c->msg_ptr = 0;
				i2c->msg_idx++;
				i2c->msg++;

				writel(I2C_CMD_READ, i2c->regs + CMDR);
			}

		} else {
			writel(I2C_CMD_READ, i2c->regs + CMDR);
		}

		break;
	}
}

/* nuc900_i2c_irq
 *
 * top level IRQ servicing routine
*/

static irqreturn_t nuc900_i2c_irq(int irqno, void *dev_id)
{
	struct nuc900_i2c *i2c = dev_id;
	unsigned long status;

	status = readl(i2c->regs + CSR);
	writel(status | IRQFLAG, i2c->regs + CSR);

	if (status & ARBIT_LOST) {
		/* deal with arbitration loss */
		dev_err(i2c->dev, "deal with arbitration loss\n");
		goto out;
	}

	if (i2c->state == STATE_IDLE) {
		dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");
		goto out;
	}

	/* pretty much this leaves us with the fact that we've
	 * transmitted or received whatever byte we last sent
	*/

	i2c_nuc900_irq_nextbyte(i2c, status);

 out:
	return IRQ_HANDLED;
}


/* nuc900_i2c_set_master
 *
 * get the i2c bus for a master transaction
*/

static int nuc900_i2c_set_master(struct nuc900_i2c *i2c)
{
	int timeout = 400;

	while (timeout-- > 0) {
		if (((readl(i2c->regs + SWR) & I2CSTART) == I2CSTART) &&
				((readl(i2c->regs + CSR) & I2CBUSY) == 0)) {
			return 0;
		}

		msleep(1);
	}

	return -ETIMEDOUT;
}

/* nuc900_i2c_doxfer
 *
 * this starts an i2c transfer
*/

static int nuc900_i2c_doxfer(struct nuc900_i2c *i2c,
			      struct i2c_msg *msgs, int num)
{
	unsigned long iicstat, timeout;
	int spins = 20;
	int ret;

	ret = nuc900_i2c_set_master(i2c);
	if (ret != 0) {
		dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
		ret = -EAGAIN;
		goto out;
	}

	spin_lock_irq(&i2c->lock);

	i2c->msg     = msgs;
	i2c->msg_num = num;
	i2c->msg_ptr = 0;
	i2c->msg_idx = 0;
	i2c->state   = STATE_START;

	nuc900_i2c_message_start(i2c, msgs);
	spin_unlock_irq(&i2c->lock);

	timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);

	ret = i2c->msg_idx;

	/* having these next two as dev_err() makes life very
	 * noisy when doing an i2cdetect
	*/

	if (timeout == 0)
		dev_dbg(i2c->dev, "timeout\n");
	else if (ret != num)
		dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);

	/* ensure the stop has been through the bus */

	dev_dbg(i2c->dev, "waiting for bus idle\n");

	/* first, try busy waiting briefly */
	do {
		iicstat = readl(i2c->regs + CSR);
	} while ((iicstat & I2CBUSY) && --spins);

	/* if that timed out sleep */
	if (!spins) {
		msleep(1);
		iicstat = readl(i2c->regs + CSR);
	}

	if (iicstat & I2CBUSY)
		dev_warn(i2c->dev, "timeout waiting for bus idle\n");

 out:
	return ret;
}

/* nuc900_i2c_xfer
 *
 * first port of call from the i2c bus code when an message needs
 * transferring across the i2c bus.
*/

static int nuc900_i2c_xfer(struct i2c_adapter *adap,
			struct i2c_msg *msgs, int num)
{
	struct nuc900_i2c *i2c = (struct nuc900_i2c *)adap->algo_data;
	int retry;
	int ret;

	nuc900_i2c_enable_irq(i2c);

	for (retry = 0; retry < adap->retries; retry++) {

		ret = nuc900_i2c_doxfer(i2c, msgs, num);

		if (ret != -EAGAIN)
			return ret;

		dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);

		udelay(100);
	}

	return -EREMOTEIO;
}

/* declare our i2c functionality */
static u32 nuc900_i2c_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART |
		I2C_FUNC_PROTOCOL_MANGLING;
}

/* i2c bus registration info */

static const struct i2c_algorithm nuc900_i2c_algorithm = {
	.master_xfer		= nuc900_i2c_xfer,
	.functionality		= nuc900_i2c_func,
};

/* nuc900_i2c_probe
 *
 * called by the bus driver when a suitable device is found
*/

static int __devinit nuc900_i2c_probe(struct platform_device *pdev)
{
	struct nuc900_i2c *i2c;
	struct nuc900_platform_i2c *pdata;
	struct resource *res;
	int ret;

	pdata = pdev->dev.platform_data;
	if (!pdata) {
		dev_err(&pdev->dev, "no platform data\n");
		return -EINVAL;
	}

	i2c = kzalloc(sizeof(struct nuc900_i2c), GFP_KERNEL);
	if (!i2c) {
		dev_err(&pdev->dev, "no memory for state\n");
		return -ENOMEM;
	}

	strlcpy(i2c->adap.name, "nuc900-i2c0", sizeof(i2c->adap.name));
	i2c->adap.owner   = THIS_MODULE;
	i2c->adap.algo    = &nuc900_i2c_algorithm;
	i2c->adap.retries = 2;
	i2c->adap.class   = I2C_CLASS_HWMON | I2C_CLASS_SPD;

	spin_lock_init(&i2c->lock);
	init_waitqueue_head(&i2c->wait);

	/* find the clock and enable it */

	i2c->dev = &pdev->dev;
	i2c->clk = clk_get(&pdev->dev, NULL);
	if (IS_ERR(i2c->clk)) {
		dev_err(&pdev->dev, "cannot get clock\n");
		ret = -ENOENT;
		goto err_noclk;
	}

	dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);

	clk_enable(i2c->clk);

	/* map the registers */

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res == NULL) {
		dev_err(&pdev->dev, "cannot find IO resource\n");
		ret = -ENOENT;
		goto err_clk;
	}

	i2c->ioarea = request_mem_region(res->start, resource_size(res),
					 pdev->name);

	if (i2c->ioarea == NULL) {
		dev_err(&pdev->dev, "cannot request IO\n");
		ret = -ENXIO;
		goto err_clk;
	}

	i2c->regs = ioremap(res->start, resource_size(res));

	if (i2c->regs == NULL) {
		dev_err(&pdev->dev, "cannot map IO\n");
		ret = -ENXIO;
		goto err_ioarea;
	}

	dev_dbg(&pdev->dev, "registers %p (%p, %p)\n",
		i2c->regs, i2c->ioarea, res);

	/* setup info block for the i2c core */

	i2c->adap.algo_data = i2c;
	i2c->adap.dev.parent = &pdev->dev;

	mfp_set_groupg(&pdev->dev, NULL);

	clk_get_rate(i2c->clk);

	ret = (i2c->clk.apbfreq)/(pdata->bus_freq * 5) - 1;
	writel(ret & 0xffff, i2c->regs + DIVIDER);

	/* find the IRQ for this unit (note, this relies on the init call to
	 * ensure no current IRQs pending
	 */

	i2c->irq = ret = platform_get_irq(pdev, 0);
	if (ret <= 0) {
		dev_err(&pdev->dev, "cannot find IRQ\n");
		goto err_iomap;
	}

	ret = request_irq(i2c->irq, nuc900_i2c_irq, IRQF_SHARED,
			  dev_name(&pdev->dev), i2c);

	if (ret != 0) {
		dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
		goto err_iomap;
	}

	/* Note, previous versions of the driver used i2c_add_adapter()
	 * to add the bus at any number. We now pass the bus number via
	 * the platform data, so if unset it will now default to always
	 * being bus 0.
	 */

	i2c->adap.nr = pdata->bus_num;

	ret = i2c_add_numbered_adapter(&i2c->adap);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to add bus to i2c core\n");
		goto err_irq;
	}

	platform_set_drvdata(pdev, i2c);

	dev_info(&pdev->dev, "%s: NUC900 I2C adapter\n",
						dev_name(&i2c->adap.dev));
	return 0;

 err_irq:
	free_irq(i2c->irq, i2c);

 err_iomap:
	iounmap(i2c->regs);

 err_ioarea:
	release_resource(i2c->ioarea);
	kfree(i2c->ioarea);

 err_clk:
	clk_disable(i2c->clk);
	clk_put(i2c->clk);

 err_noclk:
	kfree(i2c);
	return ret;
}

/* nuc900_i2c_remove
 *
 * called when device is removed from the bus
*/

static int __devexit nuc900_i2c_remove(struct platform_device *pdev)
{
	struct nuc900_i2c *i2c = platform_get_drvdata(pdev);

	i2c_del_adapter(&i2c->adap);
	free_irq(i2c->irq, i2c);

	clk_disable(i2c->clk);
	clk_put(i2c->clk);

	iounmap(i2c->regs);

	release_resource(i2c->ioarea);
	kfree(i2c->ioarea);
	kfree(i2c);

	return 0;
}

static struct platform_driver nuc900_i2c_driver = {
	.probe		= nuc900_i2c_probe,
	.remove		= __devexit_p(nuc900_i2c_remove),
	.driver		= {
		.owner	= THIS_MODULE,
		.name	= "nuc900-i2c0",
	},
};

static int __init i2c_adap_nuc900_init(void)
{
	return platform_driver_register(&nuc900_i2c_driver);
}

static void __exit i2c_adap_nuc900_exit(void)
{
	platform_driver_unregister(&nuc900_i2c_driver);
}
subsys_initcall(i2c_adap_nuc900_init);
module_exit(i2c_adap_nuc900_exit);

MODULE_DESCRIPTION("NUC900 I2C Bus driver");
MODULE_AUTHOR("Wan ZongShun, <mcuos.com-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:nuc900-i2c0");
OpenPOWER on IntegriCloud