1 /*
2 * I2C bus driver for the SH7760 I2C Interfaces.
3 *
4 * (c) 2005-2008 MSC Vertriebsges.m.b.H, Manuel Lauss <mlau@msc-ge.com>
5 *
6 * licensed under the terms outlined in the file COPYING.
7 *
8 */
9
10 #include <linux/completion.h>
11 #include <linux/delay.h>
12 #include <linux/err.h>
13 #include <linux/i2c.h>
14 #include <linux/interrupt.h>
15 #include <linux/ioport.h>
16 #include <linux/platform_device.h>
17 #include <linux/slab.h>
18 #include <linux/io.h>
19 #include <linux/module.h>
20
21 #include <asm/clock.h>
22 #include <asm/i2c-sh7760.h>
23
24 /* register offsets */
25 #define I2CSCR 0x0 /* slave ctrl */
26 #define I2CMCR 0x4 /* master ctrl */
27 #define I2CSSR 0x8 /* slave status */
28 #define I2CMSR 0xC /* master status */
29 #define I2CSIER 0x10 /* slave irq enable */
30 #define I2CMIER 0x14 /* master irq enable */
31 #define I2CCCR 0x18 /* clock dividers */
32 #define I2CSAR 0x1c /* slave address */
33 #define I2CMAR 0x20 /* master address */
34 #define I2CRXTX 0x24 /* data port */
35 #define I2CFCR 0x28 /* fifo control */
36 #define I2CFSR 0x2C /* fifo status */
37 #define I2CFIER 0x30 /* fifo irq enable */
38 #define I2CRFDR 0x34 /* rx fifo count */
39 #define I2CTFDR 0x38 /* tx fifo count */
40
41 #define REGSIZE 0x3C
42
43 #define MCR_MDBS 0x80 /* non-fifo mode switch */
44 #define MCR_FSCL 0x40 /* override SCL pin */
45 #define MCR_FSDA 0x20 /* override SDA pin */
46 #define MCR_OBPC 0x10 /* override pins */
47 #define MCR_MIE 0x08 /* master if enable */
48 #define MCR_TSBE 0x04
49 #define MCR_FSB 0x02 /* force stop bit */
50 #define MCR_ESG 0x01 /* en startbit gen. */
51
52 #define MSR_MNR 0x40 /* nack received */
53 #define MSR_MAL 0x20 /* arbitration lost */
54 #define MSR_MST 0x10 /* sent a stop */
55 #define MSR_MDE 0x08
56 #define MSR_MDT 0x04
57 #define MSR_MDR 0x02
58 #define MSR_MAT 0x01 /* slave addr xfer done */
59
60 #define MIE_MNRE 0x40 /* nack irq en */
61 #define MIE_MALE 0x20 /* arblos irq en */
62 #define MIE_MSTE 0x10 /* stop irq en */
63 #define MIE_MDEE 0x08
64 #define MIE_MDTE 0x04
65 #define MIE_MDRE 0x02
66 #define MIE_MATE 0x01 /* address sent irq en */
67
68 #define FCR_RFRST 0x02 /* reset rx fifo */
69 #define FCR_TFRST 0x01 /* reset tx fifo */
70
71 #define FSR_TEND 0x04 /* last byte sent */
72 #define FSR_RDF 0x02 /* rx fifo trigger */
73 #define FSR_TDFE 0x01 /* tx fifo empty */
74
75 #define FIER_TEIE 0x04 /* tx fifo empty irq en */
76 #define FIER_RXIE 0x02 /* rx fifo trig irq en */
77 #define FIER_TXIE 0x01 /* tx fifo trig irq en */
78
79 #define FIFO_SIZE 16
80
81 struct cami2c {
82 void __iomem *iobase;
83 struct i2c_adapter adap;
84
85 /* message processing */
86 struct i2c_msg *msg;
87 #define IDF_SEND 1
88 #define IDF_RECV 2
89 #define IDF_STOP 4
90 int flags;
91
92 #define IDS_DONE 1
93 #define IDS_ARBLOST 2
94 #define IDS_NACK 4
95 int status;
96 struct completion xfer_done;
97
98 int irq;
99 struct resource *ioarea;
100 };
101
OUT32(struct cami2c * cam,int reg,unsigned long val)102 static inline void OUT32(struct cami2c *cam, int reg, unsigned long val)
103 {
104 __raw_writel(val, (unsigned long)cam->iobase + reg);
105 }
106
IN32(struct cami2c * cam,int reg)107 static inline unsigned long IN32(struct cami2c *cam, int reg)
108 {
109 return __raw_readl((unsigned long)cam->iobase + reg);
110 }
111
sh7760_i2c_irq(int irq,void * ptr)112 static irqreturn_t sh7760_i2c_irq(int irq, void *ptr)
113 {
114 struct cami2c *id = ptr;
115 struct i2c_msg *msg = id->msg;
116 char *data = msg->buf;
117 unsigned long msr, fsr, fier, len;
118
119 msr = IN32(id, I2CMSR);
120 fsr = IN32(id, I2CFSR);
121
122 /* arbitration lost */
123 if (msr & MSR_MAL) {
124 OUT32(id, I2CMCR, 0);
125 OUT32(id, I2CSCR, 0);
126 OUT32(id, I2CSAR, 0);
127 id->status |= IDS_DONE | IDS_ARBLOST;
128 goto out;
129 }
130
131 if (msr & MSR_MNR) {
132 /* NACK handling is very screwed up. After receiving a
133 * NAK IRQ one has to wait a bit before writing to any
134 * registers, or the ctl will lock up. After that delay
135 * do a normal i2c stop. Then wait at least 1 ms before
136 * attempting another transfer or ctl will stop working
137 */
138 udelay(100); /* wait or risk ctl hang */
139 OUT32(id, I2CFCR, FCR_RFRST | FCR_TFRST);
140 OUT32(id, I2CMCR, MCR_MIE | MCR_FSB);
141 OUT32(id, I2CFIER, 0);
142 OUT32(id, I2CMIER, MIE_MSTE);
143 OUT32(id, I2CSCR, 0);
144 OUT32(id, I2CSAR, 0);
145 id->status |= IDS_NACK;
146 msr &= ~MSR_MAT;
147 fsr = 0;
148 /* In some cases the MST bit is also set. */
149 }
150
151 /* i2c-stop was sent */
152 if (msr & MSR_MST) {
153 id->status |= IDS_DONE;
154 goto out;
155 }
156
157 /* i2c slave addr was sent; set to "normal" operation */
158 if (msr & MSR_MAT)
159 OUT32(id, I2CMCR, MCR_MIE);
160
161 fier = IN32(id, I2CFIER);
162
163 if (fsr & FSR_RDF) {
164 len = IN32(id, I2CRFDR);
165 if (msg->len <= len) {
166 if (id->flags & IDF_STOP) {
167 OUT32(id, I2CMCR, MCR_MIE | MCR_FSB);
168 OUT32(id, I2CFIER, 0);
169 /* manual says: wait >= 0.5 SCL times */
170 udelay(5);
171 /* next int should be MST */
172 } else {
173 id->status |= IDS_DONE;
174 /* keep the RDF bit: ctrl holds SCL low
175 * until the setup for the next i2c_msg
176 * clears this bit.
177 */
178 fsr &= ~FSR_RDF;
179 }
180 }
181 while (msg->len && len) {
182 *data++ = IN32(id, I2CRXTX);
183 msg->len--;
184 len--;
185 }
186
187 if (msg->len) {
188 len = (msg->len >= FIFO_SIZE) ? FIFO_SIZE - 1
189 : msg->len - 1;
190
191 OUT32(id, I2CFCR, FCR_TFRST | ((len & 0xf) << 4));
192 }
193
194 } else if (id->flags & IDF_SEND) {
195 if ((fsr & FSR_TEND) && (msg->len < 1)) {
196 if (id->flags & IDF_STOP) {
197 OUT32(id, I2CMCR, MCR_MIE | MCR_FSB);
198 } else {
199 id->status |= IDS_DONE;
200 /* keep the TEND bit: ctl holds SCL low
201 * until the setup for the next i2c_msg
202 * clears this bit.
203 */
204 fsr &= ~FSR_TEND;
205 }
206 }
207 if (fsr & FSR_TDFE) {
208 while (msg->len && (IN32(id, I2CTFDR) < FIFO_SIZE)) {
209 OUT32(id, I2CRXTX, *data++);
210 msg->len--;
211 }
212
213 if (msg->len < 1) {
214 fier &= ~FIER_TXIE;
215 OUT32(id, I2CFIER, fier);
216 } else {
217 len = (msg->len >= FIFO_SIZE) ? 2 : 0;
218 OUT32(id, I2CFCR,
219 FCR_RFRST | ((len & 3) << 2));
220 }
221 }
222 }
223 out:
224 if (id->status & IDS_DONE) {
225 OUT32(id, I2CMIER, 0);
226 OUT32(id, I2CFIER, 0);
227 id->msg = NULL;
228 complete(&id->xfer_done);
229 }
230 /* clear status flags and ctrl resumes work */
231 OUT32(id, I2CMSR, ~msr);
232 OUT32(id, I2CFSR, ~fsr);
233 OUT32(id, I2CSSR, 0);
234
235 return IRQ_HANDLED;
236 }
237
238
239 /* prepare and start a master receive operation */
sh7760_i2c_mrecv(struct cami2c * id)240 static void sh7760_i2c_mrecv(struct cami2c *id)
241 {
242 int len;
243
244 id->flags |= IDF_RECV;
245
246 /* set the slave addr reg; otherwise rcv wont work! */
247 OUT32(id, I2CSAR, 0xfe);
248 OUT32(id, I2CMAR, (id->msg->addr << 1) | 1);
249
250 /* adjust rx fifo trigger */
251 if (id->msg->len >= FIFO_SIZE)
252 len = FIFO_SIZE - 1; /* trigger at fifo full */
253 else
254 len = id->msg->len - 1; /* trigger before all received */
255
256 OUT32(id, I2CFCR, FCR_RFRST | FCR_TFRST);
257 OUT32(id, I2CFCR, FCR_TFRST | ((len & 0xF) << 4));
258
259 OUT32(id, I2CMSR, 0);
260 OUT32(id, I2CMCR, MCR_MIE | MCR_ESG);
261 OUT32(id, I2CMIER, MIE_MNRE | MIE_MALE | MIE_MSTE | MIE_MATE);
262 OUT32(id, I2CFIER, FIER_RXIE);
263 }
264
265 /* prepare and start a master send operation */
sh7760_i2c_msend(struct cami2c * id)266 static void sh7760_i2c_msend(struct cami2c *id)
267 {
268 int len;
269
270 id->flags |= IDF_SEND;
271
272 /* set the slave addr reg; otherwise xmit wont work! */
273 OUT32(id, I2CSAR, 0xfe);
274 OUT32(id, I2CMAR, (id->msg->addr << 1) | 0);
275
276 /* adjust tx fifo trigger */
277 if (id->msg->len >= FIFO_SIZE)
278 len = 2; /* trig: 2 bytes left in TX fifo */
279 else
280 len = 0; /* trig: 8 bytes left in TX fifo */
281
282 OUT32(id, I2CFCR, FCR_RFRST | FCR_TFRST);
283 OUT32(id, I2CFCR, FCR_RFRST | ((len & 3) << 2));
284
285 while (id->msg->len && IN32(id, I2CTFDR) < FIFO_SIZE) {
286 OUT32(id, I2CRXTX, *(id->msg->buf));
287 (id->msg->len)--;
288 (id->msg->buf)++;
289 }
290
291 OUT32(id, I2CMSR, 0);
292 OUT32(id, I2CMCR, MCR_MIE | MCR_ESG);
293 OUT32(id, I2CFSR, 0);
294 OUT32(id, I2CMIER, MIE_MNRE | MIE_MALE | MIE_MSTE | MIE_MATE);
295 OUT32(id, I2CFIER, FIER_TEIE | (id->msg->len ? FIER_TXIE : 0));
296 }
297
sh7760_i2c_busy_check(struct cami2c * id)298 static inline int sh7760_i2c_busy_check(struct cami2c *id)
299 {
300 return (IN32(id, I2CMCR) & MCR_FSDA);
301 }
302
sh7760_i2c_master_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)303 static int sh7760_i2c_master_xfer(struct i2c_adapter *adap,
304 struct i2c_msg *msgs,
305 int num)
306 {
307 struct cami2c *id = adap->algo_data;
308 int i, retr;
309
310 if (sh7760_i2c_busy_check(id)) {
311 dev_err(&adap->dev, "sh7760-i2c%d: bus busy!\n", adap->nr);
312 return -EBUSY;
313 }
314
315 i = 0;
316 while (i < num) {
317 retr = adap->retries;
318 retry:
319 id->flags = ((i == (num-1)) ? IDF_STOP : 0);
320 id->status = 0;
321 id->msg = msgs;
322 init_completion(&id->xfer_done);
323
324 if (msgs->flags & I2C_M_RD)
325 sh7760_i2c_mrecv(id);
326 else
327 sh7760_i2c_msend(id);
328
329 wait_for_completion(&id->xfer_done);
330
331 if (id->status == 0) {
332 num = -EIO;
333 break;
334 }
335
336 if (id->status & IDS_NACK) {
337 /* wait a bit or i2c module stops working */
338 mdelay(1);
339 num = -EREMOTEIO;
340 break;
341 }
342
343 if (id->status & IDS_ARBLOST) {
344 if (retr--) {
345 mdelay(2);
346 goto retry;
347 }
348 num = -EREMOTEIO;
349 break;
350 }
351
352 msgs++;
353 i++;
354 }
355
356 id->msg = NULL;
357 id->flags = 0;
358 id->status = 0;
359
360 OUT32(id, I2CMCR, 0);
361 OUT32(id, I2CMSR, 0);
362 OUT32(id, I2CMIER, 0);
363 OUT32(id, I2CFIER, 0);
364
365 /* reset slave module registers too: master mode enables slave
366 * module for receive ops (ack, data). Without this reset,
367 * eternal bus activity might be reported after NACK / ARBLOST.
368 */
369 OUT32(id, I2CSCR, 0);
370 OUT32(id, I2CSAR, 0);
371 OUT32(id, I2CSSR, 0);
372
373 return num;
374 }
375
sh7760_i2c_func(struct i2c_adapter * adap)376 static u32 sh7760_i2c_func(struct i2c_adapter *adap)
377 {
378 return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
379 }
380
381 static const struct i2c_algorithm sh7760_i2c_algo = {
382 .master_xfer = sh7760_i2c_master_xfer,
383 .functionality = sh7760_i2c_func,
384 };
385
386 /* calculate CCR register setting for a desired scl clock. SCL clock is
387 * derived from I2C module clock (iclk) which in turn is derived from
388 * peripheral module clock (mclk, usually around 33MHz):
389 * iclk = mclk/(CDF + 1). iclk must be < 20MHz.
390 * scl = iclk/(SCGD*8 + 20).
391 */
calc_CCR(unsigned long scl_hz)392 static int calc_CCR(unsigned long scl_hz)
393 {
394 struct clk *mclk;
395 unsigned long mck, m1, dff, odff, iclk;
396 signed char cdf, cdfm;
397 int scgd, scgdm, scgds;
398
399 mclk = clk_get(NULL, "peripheral_clk");
400 if (IS_ERR(mclk)) {
401 return PTR_ERR(mclk);
402 } else {
403 mck = mclk->rate;
404 clk_put(mclk);
405 }
406
407 odff = scl_hz;
408 scgdm = cdfm = m1 = 0;
409 for (cdf = 3; cdf >= 0; cdf--) {
410 iclk = mck / (1 + cdf);
411 if (iclk >= 20000000)
412 continue;
413 scgds = ((iclk / scl_hz) - 20) >> 3;
414 for (scgd = scgds; (scgd < 63) && scgd <= scgds + 1; scgd++) {
415 m1 = iclk / (20 + (scgd << 3));
416 dff = abs(scl_hz - m1);
417 if (dff < odff) {
418 odff = dff;
419 cdfm = cdf;
420 scgdm = scgd;
421 }
422 }
423 }
424 /* fail if more than 25% off of requested SCL */
425 if (odff > (scl_hz >> 2))
426 return -EINVAL;
427
428 /* create a CCR register value */
429 return ((scgdm << 2) | cdfm);
430 }
431
sh7760_i2c_probe(struct platform_device * pdev)432 static int sh7760_i2c_probe(struct platform_device *pdev)
433 {
434 struct sh7760_i2c_platdata *pd;
435 struct resource *res;
436 struct cami2c *id;
437 int ret;
438
439 pd = dev_get_platdata(&pdev->dev);
440 if (!pd) {
441 dev_err(&pdev->dev, "no platform_data!\n");
442 ret = -ENODEV;
443 goto out0;
444 }
445
446 id = kzalloc(sizeof(struct cami2c), GFP_KERNEL);
447 if (!id) {
448 dev_err(&pdev->dev, "no mem for private data\n");
449 ret = -ENOMEM;
450 goto out0;
451 }
452
453 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
454 if (!res) {
455 dev_err(&pdev->dev, "no mmio resources\n");
456 ret = -ENODEV;
457 goto out1;
458 }
459
460 id->ioarea = request_mem_region(res->start, REGSIZE, pdev->name);
461 if (!id->ioarea) {
462 dev_err(&pdev->dev, "mmio already reserved\n");
463 ret = -EBUSY;
464 goto out1;
465 }
466
467 id->iobase = ioremap(res->start, REGSIZE);
468 if (!id->iobase) {
469 dev_err(&pdev->dev, "cannot ioremap\n");
470 ret = -ENODEV;
471 goto out2;
472 }
473
474 id->irq = platform_get_irq(pdev, 0);
475
476 id->adap.nr = pdev->id;
477 id->adap.algo = &sh7760_i2c_algo;
478 id->adap.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
479 id->adap.retries = 3;
480 id->adap.algo_data = id;
481 id->adap.dev.parent = &pdev->dev;
482 snprintf(id->adap.name, sizeof(id->adap.name),
483 "SH7760 I2C at %08lx", (unsigned long)res->start);
484
485 OUT32(id, I2CMCR, 0);
486 OUT32(id, I2CMSR, 0);
487 OUT32(id, I2CMIER, 0);
488 OUT32(id, I2CMAR, 0);
489 OUT32(id, I2CSIER, 0);
490 OUT32(id, I2CSAR, 0);
491 OUT32(id, I2CSCR, 0);
492 OUT32(id, I2CSSR, 0);
493 OUT32(id, I2CFIER, 0);
494 OUT32(id, I2CFCR, FCR_RFRST | FCR_TFRST);
495 OUT32(id, I2CFSR, 0);
496
497 ret = calc_CCR(pd->speed_khz * 1000);
498 if (ret < 0) {
499 dev_err(&pdev->dev, "invalid SCL clock: %dkHz\n",
500 pd->speed_khz);
501 goto out3;
502 }
503 OUT32(id, I2CCCR, ret);
504
505 if (request_irq(id->irq, sh7760_i2c_irq, 0,
506 SH7760_I2C_DEVNAME, id)) {
507 dev_err(&pdev->dev, "cannot get irq %d\n", id->irq);
508 ret = -EBUSY;
509 goto out3;
510 }
511
512 ret = i2c_add_numbered_adapter(&id->adap);
513 if (ret < 0)
514 goto out4;
515
516 platform_set_drvdata(pdev, id);
517
518 dev_info(&pdev->dev, "%d kHz mmio %08x irq %d\n",
519 pd->speed_khz, res->start, id->irq);
520
521 return 0;
522
523 out4:
524 free_irq(id->irq, id);
525 out3:
526 iounmap(id->iobase);
527 out2:
528 release_resource(id->ioarea);
529 kfree(id->ioarea);
530 out1:
531 kfree(id);
532 out0:
533 return ret;
534 }
535
sh7760_i2c_remove(struct platform_device * pdev)536 static int sh7760_i2c_remove(struct platform_device *pdev)
537 {
538 struct cami2c *id = platform_get_drvdata(pdev);
539
540 i2c_del_adapter(&id->adap);
541 free_irq(id->irq, id);
542 iounmap(id->iobase);
543 release_resource(id->ioarea);
544 kfree(id->ioarea);
545 kfree(id);
546
547 return 0;
548 }
549
550 static struct platform_driver sh7760_i2c_drv = {
551 .driver = {
552 .name = SH7760_I2C_DEVNAME,
553 },
554 .probe = sh7760_i2c_probe,
555 .remove = sh7760_i2c_remove,
556 };
557
558 module_platform_driver(sh7760_i2c_drv);
559
560 MODULE_LICENSE("GPL");
561 MODULE_DESCRIPTION("SH7760 I2C bus driver");
562 MODULE_AUTHOR("Manuel Lauss <mano@roarinelk.homelinux.net>");
563