1 /*
2 * linux/drivers/i2c/busses/i2c-nuc900.c
3 *
4 * Copyright (c) 2010 Nuvoton technology corporation.
5 *
6 * This driver based on S3C2410 I2C driver of Ben Dooks <ben-Y5A6D6n0/KfQXOPxS62xeg@public.gmane.org>.
7 * Written by Wan ZongShun <mcuos.com-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation;version 2 of the License.
12 *
13 */
14
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17
18 #include <linux/i2c.h>
19 #include <linux/init.h>
20 #include <linux/time.h>
21 #include <linux/interrupt.h>
22 #include <linux/delay.h>
23 #include <linux/errno.h>
24 #include <linux/err.h>
25 #include <linux/platform_device.h>
26 #include <linux/clk.h>
27 #include <linux/cpufreq.h>
28 #include <linux/slab.h>
29 #include <linux/io.h>
30
31 #include <mach/mfp.h>
32 #include <mach/i2c.h>
33
34 /* nuc900 i2c registers offset */
35
36 #define CSR 0x00
37 #define DIVIDER 0x04
38 #define CMDR 0x08
39 #define SWR 0x0C
40 #define RXR 0x10
41 #define TXR 0x14
42
43 /* nuc900 i2c CSR register bits */
44
45 #define IRQEN 0x003
46 #define I2CBUSY 0x400
47 #define I2CSTART 0x018
48 #define IRQFLAG 0x004
49 #define ARBIT_LOST 0x200
50 #define SLAVE_ACK 0x800
51
52 /* nuc900 i2c CMDR register bits */
53
54 #define I2C_CMD_START 0x10
55 #define I2C_CMD_STOP 0x08
56 #define I2C_CMD_READ 0x04
57 #define I2C_CMD_WRITE 0x02
58 #define I2C_CMD_NACK 0x01
59
60 /* i2c controller state */
61
62 enum nuc900_i2c_state {
63 STATE_IDLE,
64 STATE_START,
65 STATE_READ,
66 STATE_WRITE,
67 STATE_STOP
68 };
69
70 /* i2c controller private data */
71
72 struct nuc900_i2c {
73 spinlock_t lock;
74 wait_queue_head_t wait;
75
76 struct i2c_msg *msg;
77 unsigned int msg_num;
78 unsigned int msg_idx;
79 unsigned int msg_ptr;
80 unsigned int irq;
81
82 enum nuc900_i2c_state state;
83
84 void __iomem *regs;
85 struct clk *clk;
86 struct device *dev;
87 struct resource *ioarea;
88 struct i2c_adapter adap;
89 };
90
91 /* nuc900_i2c_master_complete
92 *
93 * complete the message and wake up the caller, using the given return code,
94 * or zero to mean ok.
95 */
96
nuc900_i2c_master_complete(struct nuc900_i2c * i2c,int ret)97 static inline void nuc900_i2c_master_complete(struct nuc900_i2c *i2c, int ret)
98 {
99 dev_dbg(i2c->dev, "master_complete %d\n", ret);
100
101 i2c->msg_ptr = 0;
102 i2c->msg = NULL;
103 i2c->msg_idx++;
104 i2c->msg_num = 0;
105 if (ret)
106 i2c->msg_idx = ret;
107
108 wake_up(&i2c->wait);
109 }
110
111 /* irq enable/disable functions */
112
nuc900_i2c_disable_irq(struct nuc900_i2c * i2c)113 static inline void nuc900_i2c_disable_irq(struct nuc900_i2c *i2c)
114 {
115 unsigned long tmp;
116
117 tmp = readl(i2c->regs + CSR);
118 writel(tmp & ~IRQEN, i2c->regs + CSR);
119 }
120
nuc900_i2c_enable_irq(struct nuc900_i2c * i2c)121 static inline void nuc900_i2c_enable_irq(struct nuc900_i2c *i2c)
122 {
123 unsigned long tmp;
124
125 tmp = readl(i2c->regs + CSR);
126 writel(tmp | IRQEN, i2c->regs + CSR);
127 }
128
129
130 /* nuc900_i2c_message_start
131 *
132 * put the start of a message onto the bus
133 */
134
nuc900_i2c_message_start(struct nuc900_i2c * i2c,struct i2c_msg * msg)135 static void nuc900_i2c_message_start(struct nuc900_i2c *i2c,
136 struct i2c_msg *msg)
137 {
138 unsigned int addr = (msg->addr & 0x7f) << 1;
139
140 if (msg->flags & I2C_M_RD)
141 addr |= 0x1;
142 writel(addr & 0xff, i2c->regs + TXR);
143 writel(I2C_CMD_START | I2C_CMD_WRITE, i2c->regs + CMDR);
144 }
145
nuc900_i2c_stop(struct nuc900_i2c * i2c,int ret)146 static inline void nuc900_i2c_stop(struct nuc900_i2c *i2c, int ret)
147 {
148
149 dev_dbg(i2c->dev, "STOP\n");
150
151 /* stop the transfer */
152 i2c->state = STATE_STOP;
153 writel(I2C_CMD_STOP, i2c->regs + CMDR);
154
155 nuc900_i2c_master_complete(i2c, ret);
156 nuc900_i2c_disable_irq(i2c);
157 }
158
159 /* helper functions to determine the current state in the set of
160 * messages we are sending
161 */
162
163 /* is_lastmsg()
164 *
165 * returns TRUE if the current message is the last in the set
166 */
167
is_lastmsg(struct nuc900_i2c * i2c)168 static inline int is_lastmsg(struct nuc900_i2c *i2c)
169 {
170 return i2c->msg_idx >= (i2c->msg_num - 1);
171 }
172
173 /* is_msglast
174 *
175 * returns TRUE if we this is the last byte in the current message
176 */
177
is_msglast(struct nuc900_i2c * i2c)178 static inline int is_msglast(struct nuc900_i2c *i2c)
179 {
180 return i2c->msg_ptr == i2c->msg->len-1;
181 }
182
183 /* is_msgend
184 *
185 * returns TRUE if we reached the end of the current message
186 */
187
is_msgend(struct nuc900_i2c * i2c)188 static inline int is_msgend(struct nuc900_i2c *i2c)
189 {
190 return i2c->msg_ptr >= i2c->msg->len;
191 }
192
193 /* i2c_nuc900_irq_nextbyte
194 *
195 * process an interrupt and work out what to do
196 */
197
i2c_nuc900_irq_nextbyte(struct nuc900_i2c * i2c,unsigned long iicstat)198 static void i2c_nuc900_irq_nextbyte(struct nuc900_i2c *i2c,
199 unsigned long iicstat)
200 {
201 unsigned char byte;
202
203 switch (i2c->state) {
204
205 case STATE_IDLE:
206 dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __func__);
207 break;
208
209 case STATE_STOP:
210 dev_err(i2c->dev, "%s: called in STATE_STOP\n", __func__);
211 nuc900_i2c_disable_irq(i2c);
212 break;
213
214 case STATE_START:
215 /* last thing we did was send a start condition on the
216 * bus, or started a new i2c message
217 */
218
219 if (iicstat & SLAVE_ACK &&
220 !(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
221 /* ack was not received... */
222
223 dev_dbg(i2c->dev, "ack was not received\n");
224 nuc900_i2c_stop(i2c, -ENXIO);
225 break;
226 }
227
228 if (i2c->msg->flags & I2C_M_RD)
229 i2c->state = STATE_READ;
230 else
231 i2c->state = STATE_WRITE;
232
233 /* terminate the transfer if there is nothing to do
234 * as this is used by the i2c probe to find devices.
235 */
236
237 if (is_lastmsg(i2c) && i2c->msg->len == 0) {
238 nuc900_i2c_stop(i2c, 0);
239 break;
240 }
241
242 if (i2c->state == STATE_READ)
243 goto prepare_read;
244
245 /* fall through to the write state, as we will need to
246 * send a byte as well
247 */
248
249 case STATE_WRITE:
250 /* we are writing data to the device... check for the
251 * end of the message, and if so, work out what to do
252 */
253
254 if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
255 if (iicstat & SLAVE_ACK) {
256 dev_dbg(i2c->dev, "WRITE: No Ack\n");
257
258 nuc900_i2c_stop(i2c, -ECONNREFUSED);
259 break;
260 }
261 }
262
263 retry_write:
264
265 if (!is_msgend(i2c)) {
266 byte = i2c->msg->buf[i2c->msg_ptr++];
267 writeb(byte, i2c->regs + TXR);
268 writel(I2C_CMD_WRITE, i2c->regs + CMDR);
269
270 } else if (!is_lastmsg(i2c)) {
271 /* we need to go to the next i2c message */
272
273 dev_dbg(i2c->dev, "WRITE: Next Message\n");
274
275 i2c->msg_ptr = 0;
276 i2c->msg_idx++;
277 i2c->msg++;
278
279 /* check to see if we need to do another message */
280 if (i2c->msg->flags & I2C_M_NOSTART) {
281
282 if (i2c->msg->flags & I2C_M_RD) {
283 /* cannot do this, the controller
284 * forces us to send a new START
285 * when we change direction
286 */
287
288 nuc900_i2c_stop(i2c, -EINVAL);
289 }
290
291 goto retry_write;
292 } else {
293 /* send the new start */
294 nuc900_i2c_message_start(i2c, i2c->msg);
295 i2c->state = STATE_START;
296 }
297
298 } else {
299 /* send stop */
300
301 nuc900_i2c_stop(i2c, 0);
302 }
303 break;
304
305 case STATE_READ:
306 /* we have a byte of data in the data register, do
307 * something with it, and then work out wether we are
308 * going to do any more read/write
309 */
310
311 byte = readb(i2c->regs + RXR);
312 i2c->msg->buf[i2c->msg_ptr++] = byte;
313
314 prepare_read:
315 if (is_msglast(i2c)) {
316 /* last byte of buffer */
317
318 if (is_lastmsg(i2c))
319 writel(I2C_CMD_READ | I2C_CMD_NACK,
320 i2c->regs + CMDR);
321
322 } else if (is_msgend(i2c)) {
323 /* ok, we've read the entire buffer, see if there
324 * is anything else we need to do
325 */
326
327 if (is_lastmsg(i2c)) {
328 /* last message, send stop and complete */
329 dev_dbg(i2c->dev, "READ: Send Stop\n");
330
331 nuc900_i2c_stop(i2c, 0);
332 } else {
333 /* go to the next transfer */
334 dev_dbg(i2c->dev, "READ: Next Transfer\n");
335
336 i2c->msg_ptr = 0;
337 i2c->msg_idx++;
338 i2c->msg++;
339
340 writel(I2C_CMD_READ, i2c->regs + CMDR);
341 }
342
343 } else {
344 writel(I2C_CMD_READ, i2c->regs + CMDR);
345 }
346
347 break;
348 }
349 }
350
351 /* nuc900_i2c_irq
352 *
353 * top level IRQ servicing routine
354 */
355
nuc900_i2c_irq(int irqno,void * dev_id)356 static irqreturn_t nuc900_i2c_irq(int irqno, void *dev_id)
357 {
358 struct nuc900_i2c *i2c = dev_id;
359 unsigned long status;
360
361 status = readl(i2c->regs + CSR);
362 writel(status | IRQFLAG, i2c->regs + CSR);
363
364 if (status & ARBIT_LOST) {
365 /* deal with arbitration loss */
366 dev_err(i2c->dev, "deal with arbitration loss\n");
367 goto out;
368 }
369
370 if (i2c->state == STATE_IDLE) {
371 dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");
372 goto out;
373 }
374
375 /* pretty much this leaves us with the fact that we've
376 * transmitted or received whatever byte we last sent
377 */
378
379 i2c_nuc900_irq_nextbyte(i2c, status);
380
381 out:
382 return IRQ_HANDLED;
383 }
384
385
386 /* nuc900_i2c_set_master
387 *
388 * get the i2c bus for a master transaction
389 */
390
nuc900_i2c_set_master(struct nuc900_i2c * i2c)391 static int nuc900_i2c_set_master(struct nuc900_i2c *i2c)
392 {
393 int timeout = 400;
394
395 while (timeout-- > 0) {
396 if (((readl(i2c->regs + SWR) & I2CSTART) == I2CSTART) &&
397 ((readl(i2c->regs + CSR) & I2CBUSY) == 0)) {
398 return 0;
399 }
400
401 msleep(1);
402 }
403
404 return -ETIMEDOUT;
405 }
406
407 /* nuc900_i2c_doxfer
408 *
409 * this starts an i2c transfer
410 */
411
nuc900_i2c_doxfer(struct nuc900_i2c * i2c,struct i2c_msg * msgs,int num)412 static int nuc900_i2c_doxfer(struct nuc900_i2c *i2c,
413 struct i2c_msg *msgs, int num)
414 {
415 unsigned long iicstat, timeout;
416 int spins = 20;
417 int ret;
418
419 ret = nuc900_i2c_set_master(i2c);
420 if (ret != 0) {
421 dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
422 ret = -EAGAIN;
423 goto out;
424 }
425
426 spin_lock_irq(&i2c->lock);
427
428 i2c->msg = msgs;
429 i2c->msg_num = num;
430 i2c->msg_ptr = 0;
431 i2c->msg_idx = 0;
432 i2c->state = STATE_START;
433
434 nuc900_i2c_message_start(i2c, msgs);
435 spin_unlock_irq(&i2c->lock);
436
437 timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
438
439 ret = i2c->msg_idx;
440
441 /* having these next two as dev_err() makes life very
442 * noisy when doing an i2cdetect
443 */
444
445 if (timeout == 0)
446 dev_dbg(i2c->dev, "timeout\n");
447 else if (ret != num)
448 dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
449
450 /* ensure the stop has been through the bus */
451
452 dev_dbg(i2c->dev, "waiting for bus idle\n");
453
454 /* first, try busy waiting briefly */
455 do {
456 iicstat = readl(i2c->regs + CSR);
457 } while ((iicstat & I2CBUSY) && --spins);
458
459 /* if that timed out sleep */
460 if (!spins) {
461 msleep(1);
462 iicstat = readl(i2c->regs + CSR);
463 }
464
465 if (iicstat & I2CBUSY)
466 dev_warn(i2c->dev, "timeout waiting for bus idle\n");
467
468 out:
469 return ret;
470 }
471
472 /* nuc900_i2c_xfer
473 *
474 * first port of call from the i2c bus code when an message needs
475 * transferring across the i2c bus.
476 */
477
nuc900_i2c_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)478 static int nuc900_i2c_xfer(struct i2c_adapter *adap,
479 struct i2c_msg *msgs, int num)
480 {
481 struct nuc900_i2c *i2c = (struct nuc900_i2c *)adap->algo_data;
482 int retry;
483 int ret;
484
485 nuc900_i2c_enable_irq(i2c);
486
487 for (retry = 0; retry < adap->retries; retry++) {
488
489 ret = nuc900_i2c_doxfer(i2c, msgs, num);
490
491 if (ret != -EAGAIN)
492 return ret;
493
494 dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);
495
496 udelay(100);
497 }
498
499 return -EREMOTEIO;
500 }
501
502 /* declare our i2c functionality */
nuc900_i2c_func(struct i2c_adapter * adap)503 static u32 nuc900_i2c_func(struct i2c_adapter *adap)
504 {
505 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
506 }
507
508 /* i2c bus registration info */
509
510 static const struct i2c_algorithm nuc900_i2c_algorithm = {
511 .master_xfer = nuc900_i2c_xfer,
512 .functionality = nuc900_i2c_func,
513 };
514
515 /* nuc900_i2c_probe
516 *
517 * called by the bus driver when a suitable device is found
518 */
519
nuc900_i2c_probe(struct platform_device * pdev)520 static int __devinit nuc900_i2c_probe(struct platform_device *pdev)
521 {
522 struct nuc900_i2c *i2c;
523 struct nuc900_platform_i2c *pdata;
524 struct resource *res;
525 int ret;
526
527 pdata = pdev->dev.platform_data;
528 if (!pdata) {
529 dev_err(&pdev->dev, "no platform data\n");
530 return -EINVAL;
531 }
532
533 i2c = kzalloc(sizeof(struct nuc900_i2c), GFP_KERNEL);
534 if (!i2c) {
535 dev_err(&pdev->dev, "no memory for state\n");
536 return -ENOMEM;
537 }
538
539 strlcpy(i2c->adap.name, "nuc900-i2c0", sizeof(i2c->adap.name));
540 i2c->adap.owner = THIS_MODULE;
541 i2c->adap.algo = &nuc900_i2c_algorithm;
542 i2c->adap.retries = 2;
543 i2c->adap.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
544
545 spin_lock_init(&i2c->lock);
546 init_waitqueue_head(&i2c->wait);
547
548 /* find the clock and enable it */
549
550 i2c->dev = &pdev->dev;
551 i2c->clk = clk_get(&pdev->dev, NULL);
552 if (IS_ERR(i2c->clk)) {
553 dev_err(&pdev->dev, "cannot get clock\n");
554 ret = -ENOENT;
555 goto err_noclk;
556 }
557
558 dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);
559
560 clk_enable(i2c->clk);
561
562 /* map the registers */
563
564 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
565 if (res == NULL) {
566 dev_err(&pdev->dev, "cannot find IO resource\n");
567 ret = -ENOENT;
568 goto err_clk;
569 }
570
571 i2c->ioarea = request_mem_region(res->start, resource_size(res),
572 pdev->name);
573
574 if (i2c->ioarea == NULL) {
575 dev_err(&pdev->dev, "cannot request IO\n");
576 ret = -ENXIO;
577 goto err_clk;
578 }
579
580 i2c->regs = ioremap(res->start, resource_size(res));
581
582 if (i2c->regs == NULL) {
583 dev_err(&pdev->dev, "cannot map IO\n");
584 ret = -ENXIO;
585 goto err_ioarea;
586 }
587
588 dev_dbg(&pdev->dev, "registers %p (%p, %p)\n",
589 i2c->regs, i2c->ioarea, res);
590
591 /* setup info block for the i2c core */
592
593 i2c->adap.algo_data = i2c;
594 i2c->adap.dev.parent = &pdev->dev;
595
596 mfp_set_groupg(&pdev->dev, NULL);
597
598 clk_get_rate(i2c->clk);
599
600 ret = (i2c->clk.apbfreq)/(pdata->bus_freq * 5) - 1;
601 writel(ret & 0xffff, i2c->regs + DIVIDER);
602
603 /* find the IRQ for this unit (note, this relies on the init call to
604 * ensure no current IRQs pending
605 */
606
607 i2c->irq = ret = platform_get_irq(pdev, 0);
608 if (ret <= 0) {
609 dev_err(&pdev->dev, "cannot find IRQ\n");
610 goto err_iomap;
611 }
612
613 ret = request_irq(i2c->irq, nuc900_i2c_irq, IRQF_SHARED,
614 dev_name(&pdev->dev), i2c);
615
616 if (ret != 0) {
617 dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
618 goto err_iomap;
619 }
620
621 /* Note, previous versions of the driver used i2c_add_adapter()
622 * to add the bus at any number. We now pass the bus number via
623 * the platform data, so if unset it will now default to always
624 * being bus 0.
625 */
626
627 i2c->adap.nr = pdata->bus_num;
628
629 ret = i2c_add_numbered_adapter(&i2c->adap);
630 if (ret < 0) {
631 dev_err(&pdev->dev, "failed to add bus to i2c core\n");
632 goto err_irq;
633 }
634
635 platform_set_drvdata(pdev, i2c);
636
637 dev_info(&pdev->dev, "%s: NUC900 I2C adapter\n",
638 dev_name(&i2c->adap.dev));
639 return 0;
640
641 err_irq:
642 free_irq(i2c->irq, i2c);
643
644 err_iomap:
645 iounmap(i2c->regs);
646
647 err_ioarea:
648 release_resource(i2c->ioarea);
649 kfree(i2c->ioarea);
650
651 err_clk:
652 clk_disable(i2c->clk);
653 clk_put(i2c->clk);
654
655 err_noclk:
656 kfree(i2c);
657 return ret;
658 }
659
660 /* nuc900_i2c_remove
661 *
662 * called when device is removed from the bus
663 */
664
nuc900_i2c_remove(struct platform_device * pdev)665 static int __devexit nuc900_i2c_remove(struct platform_device *pdev)
666 {
667 struct nuc900_i2c *i2c = platform_get_drvdata(pdev);
668
669 i2c_del_adapter(&i2c->adap);
670 free_irq(i2c->irq, i2c);
671
672 clk_disable(i2c->clk);
673 clk_put(i2c->clk);
674
675 iounmap(i2c->regs);
676
677 release_resource(i2c->ioarea);
678 kfree(i2c->ioarea);
679 kfree(i2c);
680
681 return 0;
682 }
683
684 static struct platform_driver nuc900_i2c_driver = {
685 .probe = nuc900_i2c_probe,
686 .remove = __devexit_p(nuc900_i2c_remove),
687 .driver = {
688 .owner = THIS_MODULE,
689 .name = "nuc900-i2c0",
690 },
691 };
692
i2c_adap_nuc900_init(void)693 static int __init i2c_adap_nuc900_init(void)
694 {
695 return platform_driver_register(&nuc900_i2c_driver);
696 }
697
i2c_adap_nuc900_exit(void)698 static void __exit i2c_adap_nuc900_exit(void)
699 {
700 platform_driver_unregister(&nuc900_i2c_driver);
701 }
702 subsys_initcall(i2c_adap_nuc900_init);
703 module_exit(i2c_adap_nuc900_exit);
704
705 MODULE_DESCRIPTION("NUC900 I2C Bus driver");
706 MODULE_AUTHOR("Wan ZongShun, <mcuos.com-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
707 MODULE_LICENSE("GPL");
708 MODULE_ALIAS("platform:nuc900-i2c0");
709