MIPS: I2C: Add driver for Cavium OCTEON I2C ports.
[safe/jmp/linux-2.6] / drivers / i2c / busses / i2c-octeon.c
1 /*
2  * (C) Copyright 2009-2010
3  * Nokia Siemens Networks, michael.lawnick.ext@nsn.com
4  *
5  * Portions Copyright (C) 2010 Cavium Networks, Inc.
6  *
7  * This is a driver for the i2c adapter in Cavium Networks' OCTEON processors.
8  *
9  * This file is licensed under the terms of the GNU General Public
10  * License version 2. This program is licensed "as is" without any
11  * warranty of any kind, whether express or implied.
12  */
13
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/sched.h>
17 #include <linux/init.h>
18
19 #include <linux/io.h>
20 #include <linux/i2c.h>
21 #include <linux/interrupt.h>
22 #include <linux/delay.h>
23 #include <linux/platform_device.h>
24
25 #include <asm/octeon/octeon.h>
26
27 #define DRV_NAME "i2c-octeon"
28
29 /* The previous out-of-tree version was implicitly version 1.0. */
30 #define DRV_VERSION     "2.0"
31
32 /* register offsets */
33 #define SW_TWSI  0x00
34 #define TWSI_INT 0x10
35
36 /* Controller command patterns */
37 #define SW_TWSI_V               0x8000000000000000ull
38 #define SW_TWSI_EOP_TWSI_DATA   0x0C00000100000000ull
39 #define SW_TWSI_EOP_TWSI_CTL    0x0C00000200000000ull
40 #define SW_TWSI_EOP_TWSI_CLKCTL 0x0C00000300000000ull
41 #define SW_TWSI_EOP_TWSI_STAT   0x0C00000300000000ull
42 #define SW_TWSI_EOP_TWSI_RST    0x0C00000700000000ull
43 #define SW_TWSI_OP_TWSI_CLK     0x0800000000000000ull
44 #define SW_TWSI_R               0x0100000000000000ull
45
46 /* Controller command and status bits */
47 #define TWSI_CTL_CE   0x80
48 #define TWSI_CTL_ENAB 0x40
49 #define TWSI_CTL_STA  0x20
50 #define TWSI_CTL_STP  0x10
51 #define TWSI_CTL_IFLG 0x08
52 #define TWSI_CTL_AAK  0x04
53
54 /* Some status values */
55 #define STAT_START      0x08
56 #define STAT_RSTART     0x10
57 #define STAT_TXADDR_ACK 0x18
58 #define STAT_TXDATA_ACK 0x28
59 #define STAT_RXADDR_ACK 0x40
60 #define STAT_RXDATA_ACK 0x50
61 #define STAT_IDLE       0xF8
62
63 struct octeon_i2c {
64         wait_queue_head_t queue;
65         struct i2c_adapter adap;
66         int irq;
67         int twsi_freq;
68         int sys_freq;
69         resource_size_t twsi_phys;
70         void __iomem *twsi_base;
71         resource_size_t regsize;
72         struct device *dev;
73 };
74
75 /**
76  * octeon_i2c_write_sw - write an I2C core register.
77  * @i2c: The struct octeon_i2c.
78  * @eop_reg: Register selector.
79  * @data: Value to be written.
80  *
81  * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
82  */
83 static void octeon_i2c_write_sw(struct octeon_i2c *i2c,
84                                 u64 eop_reg,
85                                 u8 data)
86 {
87         u64 tmp;
88
89         __raw_writeq(SW_TWSI_V | eop_reg | data, i2c->twsi_base + SW_TWSI);
90         do {
91                 tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
92         } while ((tmp & SW_TWSI_V) != 0);
93 }
94
95 /**
96  * octeon_i2c_read_sw - write an I2C core register.
97  * @i2c: The struct octeon_i2c.
98  * @eop_reg: Register selector.
99  *
100  * Returns the data.
101  *
102  * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
103  */
104 static u8 octeon_i2c_read_sw(struct octeon_i2c *i2c, u64 eop_reg)
105 {
106         u64 tmp;
107
108         __raw_writeq(SW_TWSI_V | eop_reg | SW_TWSI_R, i2c->twsi_base + SW_TWSI);
109         do {
110                 tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
111         } while ((tmp & SW_TWSI_V) != 0);
112
113         return tmp & 0xFF;
114 }
115
116 /**
117  * octeon_i2c_write_int - write the TWSI_INT register
118  * @i2c: The struct octeon_i2c.
119  * @data: Value to be written.
120  */
121 static void octeon_i2c_write_int(struct octeon_i2c *i2c, u64 data)
122 {
123         u64 tmp;
124
125         __raw_writeq(data, i2c->twsi_base + TWSI_INT);
126         tmp = __raw_readq(i2c->twsi_base + TWSI_INT);
127 }
128
129 /**
130  * octeon_i2c_int_enable - enable the TS interrupt.
131  * @i2c: The struct octeon_i2c.
132  *
133  * The interrupt will be asserted when there is non-STAT_IDLE state in
134  * the SW_TWSI_EOP_TWSI_STAT register.
135  */
136 static void octeon_i2c_int_enable(struct octeon_i2c *i2c)
137 {
138         octeon_i2c_write_int(i2c, 0x40);
139 }
140
141 /**
142  * octeon_i2c_int_disable - disable the TS interrupt.
143  * @i2c: The struct octeon_i2c.
144  */
145 static void octeon_i2c_int_disable(struct octeon_i2c *i2c)
146 {
147         octeon_i2c_write_int(i2c, 0);
148 }
149
150 /**
151  * octeon_i2c_unblock - unblock the bus.
152  * @i2c: The struct octeon_i2c.
153  *
154  * If there was a reset while a device was driving 0 to bus,
155  * bus is blocked. We toggle it free manually by some clock
156  * cycles and send a stop.
157  */
158 static void octeon_i2c_unblock(struct octeon_i2c *i2c)
159 {
160         int i;
161
162         dev_dbg(i2c->dev, "%s\n", __func__);
163         for (i = 0; i < 9; i++) {
164                 octeon_i2c_write_int(i2c, 0x0);
165                 udelay(5);
166                 octeon_i2c_write_int(i2c, 0x200);
167                 udelay(5);
168         }
169         octeon_i2c_write_int(i2c, 0x300);
170         udelay(5);
171         octeon_i2c_write_int(i2c, 0x100);
172         udelay(5);
173         octeon_i2c_write_int(i2c, 0x0);
174 }
175
176 /**
177  * octeon_i2c_isr - the interrupt service routine.
178  * @int: The irq, unused.
179  * @dev_id: Our struct octeon_i2c.
180  */
181 static irqreturn_t octeon_i2c_isr(int irq, void *dev_id)
182 {
183         struct octeon_i2c *i2c = dev_id;
184
185         octeon_i2c_int_disable(i2c);
186         wake_up_interruptible(&i2c->queue);
187
188         return IRQ_HANDLED;
189 }
190
191
192 static int octeon_i2c_test_iflg(struct octeon_i2c *i2c)
193 {
194         return (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_CTL) & TWSI_CTL_IFLG) != 0;
195 }
196
197 /**
198  * octeon_i2c_wait - wait for the IFLG to be set.
199  * @i2c: The struct octeon_i2c.
200  *
201  * Returns 0 on success, otherwise a negative errno.
202  */
203 static int octeon_i2c_wait(struct octeon_i2c *i2c)
204 {
205         int result;
206
207         octeon_i2c_int_enable(i2c);
208
209         result = wait_event_interruptible_timeout(i2c->queue,
210                                                   octeon_i2c_test_iflg(i2c),
211                                                   i2c->adap.timeout);
212
213         octeon_i2c_int_disable(i2c);
214
215         if (result < 0) {
216                 dev_dbg(i2c->dev, "%s: wait interrupted\n", __func__);
217                 return result;
218         } else if (result == 0) {
219                 dev_dbg(i2c->dev, "%s: timeout\n", __func__);
220                 result = -ETIMEDOUT;
221         }
222
223         return 0;
224 }
225
226 /**
227  * octeon_i2c_start - send START to the bus.
228  * @i2c: The struct octeon_i2c.
229  *
230  * Returns 0 on success, otherwise a negative errno.
231  */
232 static int octeon_i2c_start(struct octeon_i2c *i2c)
233 {
234         u8 data;
235         int result;
236
237         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
238                                 TWSI_CTL_ENAB | TWSI_CTL_STA);
239
240         result = octeon_i2c_wait(i2c);
241         if (result) {
242                 if (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT) == STAT_IDLE) {
243                         /*
244                          * Controller refused to send start flag May
245                          * be a client is holding SDA low - let's try
246                          * to free it.
247                          */
248                         octeon_i2c_unblock(i2c);
249                         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
250                                             TWSI_CTL_ENAB | TWSI_CTL_STA);
251
252                         result = octeon_i2c_wait(i2c);
253                 }
254                 if (result)
255                         return result;
256         }
257
258         data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
259         if ((data != STAT_START) && (data != STAT_RSTART)) {
260                 dev_err(i2c->dev, "%s: bad status (0x%x)\n", __func__, data);
261                 return -EIO;
262         }
263
264         return 0;
265 }
266
267 /**
268  * octeon_i2c_stop - send STOP to the bus.
269  * @i2c: The struct octeon_i2c.
270  *
271  * Returns 0 on success, otherwise a negative errno.
272  */
273 static int octeon_i2c_stop(struct octeon_i2c *i2c)
274 {
275         u8 data;
276
277         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
278                             TWSI_CTL_ENAB | TWSI_CTL_STP);
279
280         data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
281
282         if (data != STAT_IDLE) {
283                 dev_err(i2c->dev, "%s: bad status(0x%x)\n", __func__, data);
284                 return -EIO;
285         }
286         return 0;
287 }
288
289 /**
290  * octeon_i2c_write - send data to the bus.
291  * @i2c: The struct octeon_i2c.
292  * @target: Target address.
293  * @data: Pointer to the data to be sent.
294  * @length: Length of the data.
295  *
296  * The address is sent over the bus, then the data.
297  *
298  * Returns 0 on success, otherwise a negative errno.
299  */
300 static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
301                             const u8 *data, int length)
302 {
303         int i, result;
304         u8 tmp;
305
306         result = octeon_i2c_start(i2c);
307         if (result)
308                 return result;
309
310         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, target << 1);
311         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
312
313         result = octeon_i2c_wait(i2c);
314         if (result)
315                 return result;
316
317         for (i = 0; i < length; i++) {
318                 tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
319                 if ((tmp != STAT_TXADDR_ACK) && (tmp != STAT_TXDATA_ACK)) {
320                         dev_err(i2c->dev,
321                                 "%s: bad status before write (0x%x)\n",
322                                 __func__, tmp);
323                         return -EIO;
324                 }
325
326                 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, data[i]);
327                 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
328
329                 result = octeon_i2c_wait(i2c);
330                 if (result)
331                         return result;
332         }
333
334         return 0;
335 }
336
337 /**
338  * octeon_i2c_read - receive data from the bus.
339  * @i2c: The struct octeon_i2c.
340  * @target: Target address.
341  * @data: Pointer to the location to store the datae .
342  * @length: Length of the data.
343  *
344  * The address is sent over the bus, then the data is read.
345  *
346  * Returns 0 on success, otherwise a negative errno.
347  */
348 static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
349                            u8 *data, int length)
350 {
351         int i, result;
352         u8 tmp;
353
354         if (length < 1)
355                 return -EINVAL;
356
357         result = octeon_i2c_start(i2c);
358         if (result)
359                 return result;
360
361         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, (target<<1) | 1);
362         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
363
364         result = octeon_i2c_wait(i2c);
365         if (result)
366                 return result;
367
368         for (i = 0; i < length; i++) {
369                 tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
370                 if ((tmp != STAT_RXDATA_ACK) && (tmp != STAT_RXADDR_ACK)) {
371                         dev_err(i2c->dev,
372                                 "%s: bad status before read (0x%x)\n",
373                                 __func__, tmp);
374                         return -EIO;
375                 }
376
377                 if (i+1 < length)
378                         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
379                                                 TWSI_CTL_ENAB | TWSI_CTL_AAK);
380                 else
381                         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
382                                                 TWSI_CTL_ENAB);
383
384                 result = octeon_i2c_wait(i2c);
385                 if (result)
386                         return result;
387
388                 data[i] = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_DATA);
389         }
390         return 0;
391 }
392
393 /**
394  * octeon_i2c_xfer - The driver's master_xfer function.
395  * @adap: Pointer to the i2c_adapter structure.
396  * @msgs: Pointer to the messages to be processed.
397  * @num: Length of the MSGS array.
398  *
399  * Returns the number of messages processed, or a negative errno on
400  * failure.
401  */
402 static int octeon_i2c_xfer(struct i2c_adapter *adap,
403                            struct i2c_msg *msgs,
404                            int num)
405 {
406         struct i2c_msg *pmsg;
407         int i;
408         int ret = 0;
409         struct octeon_i2c *i2c = i2c_get_adapdata(adap);
410
411         for (i = 0; ret == 0 && i < num; i++) {
412                 pmsg = &msgs[i];
413                 dev_dbg(i2c->dev,
414                         "Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
415                          pmsg->flags & I2C_M_RD ? "read" : "write",
416                          pmsg->len, pmsg->addr, i + 1, num);
417                 if (pmsg->flags & I2C_M_RD)
418                         ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
419                                                 pmsg->len);
420                 else
421                         ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf,
422                                                 pmsg->len);
423         }
424         octeon_i2c_stop(i2c);
425
426         return (ret != 0) ? ret : num;
427 }
428
429 static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
430 {
431         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
432 }
433
434 static const struct i2c_algorithm octeon_i2c_algo = {
435         .master_xfer = octeon_i2c_xfer,
436         .functionality = octeon_i2c_functionality,
437 };
438
439 static struct i2c_adapter octeon_i2c_ops = {
440         .owner = THIS_MODULE,
441         .name = "OCTEON adapter",
442         .algo = &octeon_i2c_algo,
443         .timeout = 2,
444 };
445
446 /**
447  * octeon_i2c_setclock - Calculate and set clock divisors.
448  */
449 static int __init octeon_i2c_setclock(struct octeon_i2c *i2c)
450 {
451         int tclk, thp_base, inc, thp_idx, mdiv_idx, ndiv_idx, foscl, diff;
452         int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = 1000000;
453
454         for (ndiv_idx = 0; ndiv_idx < 8 && delta_hz != 0; ndiv_idx++) {
455                 /*
456                  * An mdiv value of less than 2 seems to not work well
457                  * with ds1337 RTCs, so we constrain it to larger
458                  * values.
459                  */
460                 for (mdiv_idx = 15; mdiv_idx >= 2 && delta_hz != 0; mdiv_idx--) {
461                         /*
462                          * For given ndiv and mdiv values check the
463                          * two closest thp values.
464                          */
465                         tclk = i2c->twsi_freq * (mdiv_idx + 1) * 10;
466                         tclk *= (1 << ndiv_idx);
467                         thp_base = (i2c->sys_freq / (tclk * 2)) - 1;
468                         for (inc = 0; inc <= 1; inc++) {
469                                 thp_idx = thp_base + inc;
470                                 if (thp_idx < 5 || thp_idx > 0xff)
471                                         continue;
472
473                                 foscl = i2c->sys_freq / (2 * (thp_idx + 1));
474                                 foscl = foscl / (1 << ndiv_idx);
475                                 foscl = foscl / (mdiv_idx + 1) / 10;
476                                 diff = abs(foscl - i2c->twsi_freq);
477                                 if (diff < delta_hz) {
478                                         delta_hz = diff;
479                                         thp = thp_idx;
480                                         mdiv = mdiv_idx;
481                                         ndiv = ndiv_idx;
482                                 }
483                         }
484                 }
485         }
486         octeon_i2c_write_sw(i2c, SW_TWSI_OP_TWSI_CLK, thp);
487         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CLKCTL, (mdiv << 3) | ndiv);
488
489         return 0;
490 }
491
492 static int __init octeon_i2c_initlowlevel(struct octeon_i2c *i2c)
493 {
494         u8 status;
495         int tries;
496
497         /* disable high level controller, enable bus access */
498         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
499
500         /* reset controller */
501         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_RST, 0);
502
503         for (tries = 10; tries; tries--) {
504                 udelay(1);
505                 status = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
506                 if (status == STAT_IDLE)
507                         return 0;
508         }
509         dev_err(i2c->dev, "%s: TWSI_RST failed! (0x%x)\n", __func__, status);
510         return -EIO;
511 }
512
513 static int __devinit octeon_i2c_probe(struct platform_device *pdev)
514 {
515         int irq, result = 0;
516         struct octeon_i2c *i2c;
517         struct octeon_i2c_data *i2c_data;
518         struct resource *res_mem;
519
520         /* All adaptors have an irq.  */
521         irq = platform_get_irq(pdev, 0);
522         if (irq < 0)
523                 return irq;
524
525         i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
526         if (!i2c) {
527                 dev_err(&pdev->dev, "kzalloc failed\n");
528                 result = -ENOMEM;
529                 goto out;
530         }
531         i2c->dev = &pdev->dev;
532         i2c_data = pdev->dev.platform_data;
533
534         res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
535
536         if (res_mem == NULL) {
537                 dev_err(i2c->dev, "found no memory resource\n");
538                 result = -ENXIO;
539                 goto fail_region;
540         }
541
542         if (i2c_data == NULL) {
543                 dev_err(i2c->dev, "no I2C frequency data\n");
544                 result = -ENXIO;
545                 goto fail_region;
546         }
547
548         i2c->twsi_phys = res_mem->start;
549         i2c->regsize = resource_size(res_mem);
550         i2c->twsi_freq = i2c_data->i2c_freq;
551         i2c->sys_freq = i2c_data->sys_freq;
552
553         if (!request_mem_region(i2c->twsi_phys, i2c->regsize, res_mem->name)) {
554                 dev_err(i2c->dev, "request_mem_region failed\n");
555                 goto fail_region;
556         }
557         i2c->twsi_base = ioremap(i2c->twsi_phys, i2c->regsize);
558
559         init_waitqueue_head(&i2c->queue);
560
561         i2c->irq = irq;
562
563         result = request_irq(i2c->irq, octeon_i2c_isr, 0, DRV_NAME, i2c);
564         if (result < 0) {
565                 dev_err(i2c->dev, "failed to attach interrupt\n");
566                 goto fail_irq;
567         }
568
569         result = octeon_i2c_initlowlevel(i2c);
570         if (result) {
571                 dev_err(i2c->dev, "init low level failed\n");
572                 goto  fail_add;
573         }
574
575         result = octeon_i2c_setclock(i2c);
576         if (result) {
577                 dev_err(i2c->dev, "clock init failed\n");
578                 goto  fail_add;
579         }
580
581         i2c->adap = octeon_i2c_ops;
582         i2c->adap.dev.parent = &pdev->dev;
583         i2c->adap.nr = pdev->id >= 0 ? pdev->id : 0;
584         i2c_set_adapdata(&i2c->adap, i2c);
585         platform_set_drvdata(pdev, i2c);
586
587         result = i2c_add_numbered_adapter(&i2c->adap);
588         if (result < 0) {
589                 dev_err(i2c->dev, "failed to add adapter\n");
590                 goto fail_add;
591         }
592
593         dev_info(i2c->dev, "version %s\n", DRV_VERSION);
594
595         return result;
596
597 fail_add:
598         platform_set_drvdata(pdev, NULL);
599         free_irq(i2c->irq, i2c);
600 fail_irq:
601         iounmap(i2c->twsi_base);
602         release_mem_region(i2c->twsi_phys, i2c->regsize);
603 fail_region:
604         kfree(i2c);
605 out:
606         return result;
607 };
608
609 static int __devexit octeon_i2c_remove(struct platform_device *pdev)
610 {
611         struct octeon_i2c *i2c = platform_get_drvdata(pdev);
612
613         i2c_del_adapter(&i2c->adap);
614         platform_set_drvdata(pdev, NULL);
615         free_irq(i2c->irq, i2c);
616         iounmap(i2c->twsi_base);
617         release_mem_region(i2c->twsi_phys, i2c->regsize);
618         kfree(i2c);
619         return 0;
620 };
621
622 static struct platform_driver octeon_i2c_driver = {
623         .probe          = octeon_i2c_probe,
624         .remove         = __devexit_p(octeon_i2c_remove),
625         .driver         = {
626                 .owner  = THIS_MODULE,
627                 .name   = DRV_NAME,
628         },
629 };
630
631 static int __init octeon_i2c_init(void)
632 {
633         int rv;
634
635         rv = platform_driver_register(&octeon_i2c_driver);
636         return rv;
637 }
638
639 static void __exit octeon_i2c_exit(void)
640 {
641         platform_driver_unregister(&octeon_i2c_driver);
642 }
643
644 MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
645 MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
646 MODULE_LICENSE("GPL");
647 MODULE_VERSION(DRV_VERSION);
648 MODULE_ALIAS("platform:" DRV_NAME);
649
650 module_init(octeon_i2c_init);
651 module_exit(octeon_i2c_exit);