Version:  2.0.40 2.2.26 2.4.37 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15

Linux/drivers/i2c/busses/i2c-nuc900.c

  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 <linux/platform_data/i2c-nuc900.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 
 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 
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 
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 
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 
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 
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 
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 
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 
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 whether 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 
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 
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 
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 
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 */
503 static u32 nuc900_i2c_func(struct i2c_adapter *adap)
504 {
505         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART |
506                 I2C_FUNC_PROTOCOL_MANGLING;
507 }
508 
509 /* i2c bus registration info */
510 
511 static const struct i2c_algorithm nuc900_i2c_algorithm = {
512         .master_xfer            = nuc900_i2c_xfer,
513         .functionality          = nuc900_i2c_func,
514 };
515 
516 /* nuc900_i2c_probe
517  *
518  * called by the bus driver when a suitable device is found
519 */
520 
521 static int nuc900_i2c_probe(struct platform_device *pdev)
522 {
523         struct nuc900_i2c *i2c;
524         struct nuc900_platform_i2c *pdata;
525         struct resource *res;
526         int ret;
527 
528         pdata = dev_get_platdata(&pdev->dev);
529         if (!pdata) {
530                 dev_err(&pdev->dev, "no platform data\n");
531                 return -EINVAL;
532         }
533 
534         i2c = kzalloc(sizeof(struct nuc900_i2c), GFP_KERNEL);
535         if (!i2c) {
536                 dev_err(&pdev->dev, "no memory for state\n");
537                 return -ENOMEM;
538         }
539 
540         strlcpy(i2c->adap.name, "nuc900-i2c0", sizeof(i2c->adap.name));
541         i2c->adap.owner   = THIS_MODULE;
542         i2c->adap.algo    = &nuc900_i2c_algorithm;
543         i2c->adap.retries = 2;
544         i2c->adap.class   = I2C_CLASS_HWMON | I2C_CLASS_SPD;
545 
546         spin_lock_init(&i2c->lock);
547         init_waitqueue_head(&i2c->wait);
548 
549         /* find the clock and enable it */
550 
551         i2c->dev = &pdev->dev;
552         i2c->clk = clk_get(&pdev->dev, NULL);
553         if (IS_ERR(i2c->clk)) {
554                 dev_err(&pdev->dev, "cannot get clock\n");
555                 ret = -ENOENT;
556                 goto err_noclk;
557         }
558 
559         dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);
560 
561         clk_enable(i2c->clk);
562 
563         /* map the registers */
564 
565         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
566         if (res == NULL) {
567                 dev_err(&pdev->dev, "cannot find IO resource\n");
568                 ret = -ENOENT;
569                 goto err_clk;
570         }
571 
572         i2c->ioarea = request_mem_region(res->start, resource_size(res),
573                                          pdev->name);
574 
575         if (i2c->ioarea == NULL) {
576                 dev_err(&pdev->dev, "cannot request IO\n");
577                 ret = -ENXIO;
578                 goto err_clk;
579         }
580 
581         i2c->regs = ioremap(res->start, resource_size(res));
582 
583         if (i2c->regs == NULL) {
584                 dev_err(&pdev->dev, "cannot map IO\n");
585                 ret = -ENXIO;
586                 goto err_ioarea;
587         }
588 
589         dev_dbg(&pdev->dev, "registers %p (%p, %p)\n",
590                 i2c->regs, i2c->ioarea, res);
591 
592         /* setup info block for the i2c core */
593 
594         i2c->adap.algo_data = i2c;
595         i2c->adap.dev.parent = &pdev->dev;
596 
597         mfp_set_groupg(&pdev->dev, NULL);
598 
599         clk_get_rate(i2c->clk);
600 
601         ret = (i2c->clk.apbfreq)/(pdata->bus_freq * 5) - 1;
602         writel(ret & 0xffff, i2c->regs + DIVIDER);
603 
604         /* find the IRQ for this unit (note, this relies on the init call to
605          * ensure no current IRQs pending
606          */
607 
608         i2c->irq = ret = platform_get_irq(pdev, 0);
609         if (ret <= 0) {
610                 dev_err(&pdev->dev, "cannot find IRQ\n");
611                 goto err_iomap;
612         }
613 
614         ret = request_irq(i2c->irq, nuc900_i2c_irq, IRQF_SHARED,
615                           dev_name(&pdev->dev), i2c);
616 
617         if (ret != 0) {
618                 dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
619                 goto err_iomap;
620         }
621 
622         /* Note, previous versions of the driver used i2c_add_adapter()
623          * to add the bus at any number. We now pass the bus number via
624          * the platform data, so if unset it will now default to always
625          * being bus 0.
626          */
627 
628         i2c->adap.nr = pdata->bus_num;
629 
630         ret = i2c_add_numbered_adapter(&i2c->adap);
631         if (ret < 0) {
632                 dev_err(&pdev->dev, "failed to add bus to i2c core\n");
633                 goto err_irq;
634         }
635 
636         platform_set_drvdata(pdev, i2c);
637 
638         dev_info(&pdev->dev, "%s: NUC900 I2C adapter\n",
639                                                 dev_name(&i2c->adap.dev));
640         return 0;
641 
642  err_irq:
643         free_irq(i2c->irq, i2c);
644 
645  err_iomap:
646         iounmap(i2c->regs);
647 
648  err_ioarea:
649         release_resource(i2c->ioarea);
650         kfree(i2c->ioarea);
651 
652  err_clk:
653         clk_disable(i2c->clk);
654         clk_put(i2c->clk);
655 
656  err_noclk:
657         kfree(i2c);
658         return ret;
659 }
660 
661 /* nuc900_i2c_remove
662  *
663  * called when device is removed from the bus
664 */
665 
666 static int nuc900_i2c_remove(struct platform_device *pdev)
667 {
668         struct nuc900_i2c *i2c = platform_get_drvdata(pdev);
669 
670         i2c_del_adapter(&i2c->adap);
671         free_irq(i2c->irq, i2c);
672 
673         clk_disable(i2c->clk);
674         clk_put(i2c->clk);
675 
676         iounmap(i2c->regs);
677 
678         release_resource(i2c->ioarea);
679         kfree(i2c->ioarea);
680         kfree(i2c);
681 
682         return 0;
683 }
684 
685 static struct platform_driver nuc900_i2c_driver = {
686         .probe          = nuc900_i2c_probe,
687         .remove         = nuc900_i2c_remove,
688         .driver         = {
689                 .owner  = THIS_MODULE,
690                 .name   = "nuc900-i2c0",
691         },
692 };
693 
694 static int __init i2c_adap_nuc900_init(void)
695 {
696         return platform_driver_register(&nuc900_i2c_driver);
697 }
698 
699 static void __exit i2c_adap_nuc900_exit(void)
700 {
701         platform_driver_unregister(&nuc900_i2c_driver);
702 }
703 subsys_initcall(i2c_adap_nuc900_init);
704 module_exit(i2c_adap_nuc900_exit);
705 
706 MODULE_DESCRIPTION("NUC900 I2C Bus driver");
707 MODULE_AUTHOR("Wan ZongShun, <mcuos.com-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
708 MODULE_LICENSE("GPL");
709 MODULE_ALIAS("platform:nuc900-i2c0");
710 

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