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Merge branch 'timers/core' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
[~andy/linux] / 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, 2011 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/platform_device.h>
15 #include <linux/interrupt.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/delay.h>
19 #include <linux/sched.h>
20 #include <linux/slab.h>
21 #include <linux/init.h>
22 #include <linux/i2c.h>
23 #include <linux/io.h>
24 #include <linux/of.h>
25
26 #include <asm/octeon/octeon.h>
27
28 #define DRV_NAME "i2c-octeon"
29
30 /* The previous out-of-tree version was implicitly version 1.0. */
31 #define DRV_VERSION     "2.0"
32
33 /* register offsets */
34 #define SW_TWSI  0x00
35 #define TWSI_INT 0x10
36
37 /* Controller command patterns */
38 #define SW_TWSI_V               0x8000000000000000ull
39 #define SW_TWSI_EOP_TWSI_DATA   0x0C00000100000000ull
40 #define SW_TWSI_EOP_TWSI_CTL    0x0C00000200000000ull
41 #define SW_TWSI_EOP_TWSI_CLKCTL 0x0C00000300000000ull
42 #define SW_TWSI_EOP_TWSI_STAT   0x0C00000300000000ull
43 #define SW_TWSI_EOP_TWSI_RST    0x0C00000700000000ull
44 #define SW_TWSI_OP_TWSI_CLK     0x0800000000000000ull
45 #define SW_TWSI_R               0x0100000000000000ull
46
47 /* Controller command and status bits */
48 #define TWSI_CTL_CE   0x80
49 #define TWSI_CTL_ENAB 0x40
50 #define TWSI_CTL_STA  0x20
51 #define TWSI_CTL_STP  0x10
52 #define TWSI_CTL_IFLG 0x08
53 #define TWSI_CTL_AAK  0x04
54
55 /* Some status values */
56 #define STAT_START      0x08
57 #define STAT_RSTART     0x10
58 #define STAT_TXADDR_ACK 0x18
59 #define STAT_TXDATA_ACK 0x28
60 #define STAT_RXADDR_ACK 0x40
61 #define STAT_RXDATA_ACK 0x50
62 #define STAT_IDLE       0xF8
63
64 struct octeon_i2c {
65         wait_queue_head_t queue;
66         struct i2c_adapter adap;
67         int irq;
68         u32 twsi_freq;
69         int sys_freq;
70         resource_size_t twsi_phys;
71         void __iomem *twsi_base;
72         resource_size_t regsize;
73         struct device *dev;
74 };
75
76 /**
77  * octeon_i2c_write_sw - write an I2C core register.
78  * @i2c: The struct octeon_i2c.
79  * @eop_reg: Register selector.
80  * @data: Value to be written.
81  *
82  * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
83  */
84 static void octeon_i2c_write_sw(struct octeon_i2c *i2c,
85                                 u64 eop_reg,
86                                 u8 data)
87 {
88         u64 tmp;
89
90         __raw_writeq(SW_TWSI_V | eop_reg | data, i2c->twsi_base + SW_TWSI);
91         do {
92                 tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
93         } while ((tmp & SW_TWSI_V) != 0);
94 }
95
96 /**
97  * octeon_i2c_read_sw - write an I2C core register.
98  * @i2c: The struct octeon_i2c.
99  * @eop_reg: Register selector.
100  *
101  * Returns the data.
102  *
103  * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
104  */
105 static u8 octeon_i2c_read_sw(struct octeon_i2c *i2c, u64 eop_reg)
106 {
107         u64 tmp;
108
109         __raw_writeq(SW_TWSI_V | eop_reg | SW_TWSI_R, i2c->twsi_base + SW_TWSI);
110         do {
111                 tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
112         } while ((tmp & SW_TWSI_V) != 0);
113
114         return tmp & 0xFF;
115 }
116
117 /**
118  * octeon_i2c_write_int - write the TWSI_INT register
119  * @i2c: The struct octeon_i2c.
120  * @data: Value to be written.
121  */
122 static void octeon_i2c_write_int(struct octeon_i2c *i2c, u64 data)
123 {
124         __raw_writeq(data, i2c->twsi_base + TWSI_INT);
125         __raw_readq(i2c->twsi_base + TWSI_INT);
126 }
127
128 /**
129  * octeon_i2c_int_enable - enable the TS interrupt.
130  * @i2c: The struct octeon_i2c.
131  *
132  * The interrupt will be asserted when there is non-STAT_IDLE state in
133  * the SW_TWSI_EOP_TWSI_STAT register.
134  */
135 static void octeon_i2c_int_enable(struct octeon_i2c *i2c)
136 {
137         octeon_i2c_write_int(i2c, 0x40);
138 }
139
140 /**
141  * octeon_i2c_int_disable - disable the TS interrupt.
142  * @i2c: The struct octeon_i2c.
143  */
144 static void octeon_i2c_int_disable(struct octeon_i2c *i2c)
145 {
146         octeon_i2c_write_int(i2c, 0);
147 }
148
149 /**
150  * octeon_i2c_unblock - unblock the bus.
151  * @i2c: The struct octeon_i2c.
152  *
153  * If there was a reset while a device was driving 0 to bus,
154  * bus is blocked. We toggle it free manually by some clock
155  * cycles and send a stop.
156  */
157 static void octeon_i2c_unblock(struct octeon_i2c *i2c)
158 {
159         int i;
160
161         dev_dbg(i2c->dev, "%s\n", __func__);
162         for (i = 0; i < 9; i++) {
163                 octeon_i2c_write_int(i2c, 0x0);
164                 udelay(5);
165                 octeon_i2c_write_int(i2c, 0x200);
166                 udelay(5);
167         }
168         octeon_i2c_write_int(i2c, 0x300);
169         udelay(5);
170         octeon_i2c_write_int(i2c, 0x100);
171         udelay(5);
172         octeon_i2c_write_int(i2c, 0x0);
173 }
174
175 /**
176  * octeon_i2c_isr - the interrupt service routine.
177  * @int: The irq, unused.
178  * @dev_id: Our struct octeon_i2c.
179  */
180 static irqreturn_t octeon_i2c_isr(int irq, void *dev_id)
181 {
182         struct octeon_i2c *i2c = dev_id;
183
184         octeon_i2c_int_disable(i2c);
185         wake_up(&i2c->queue);
186
187         return IRQ_HANDLED;
188 }
189
190
191 static int octeon_i2c_test_iflg(struct octeon_i2c *i2c)
192 {
193         return (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_CTL) & TWSI_CTL_IFLG) != 0;
194 }
195
196 /**
197  * octeon_i2c_wait - wait for the IFLG to be set.
198  * @i2c: The struct octeon_i2c.
199  *
200  * Returns 0 on success, otherwise a negative errno.
201  */
202 static int octeon_i2c_wait(struct octeon_i2c *i2c)
203 {
204         int result;
205
206         octeon_i2c_int_enable(i2c);
207
208         result = wait_event_timeout(i2c->queue,
209                                         octeon_i2c_test_iflg(i2c),
210                                         i2c->adap.timeout);
211
212         octeon_i2c_int_disable(i2c);
213
214         if (result < 0) {
215                 dev_dbg(i2c->dev, "%s: wait interrupted\n", __func__);
216                 return result;
217         } else if (result == 0) {
218                 dev_dbg(i2c->dev, "%s: timeout\n", __func__);
219                 return -ETIMEDOUT;
220         }
221
222         return 0;
223 }
224
225 /**
226  * octeon_i2c_start - send START to the bus.
227  * @i2c: The struct octeon_i2c.
228  *
229  * Returns 0 on success, otherwise a negative errno.
230  */
231 static int octeon_i2c_start(struct octeon_i2c *i2c)
232 {
233         u8 data;
234         int result;
235
236         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
237                                 TWSI_CTL_ENAB | TWSI_CTL_STA);
238
239         result = octeon_i2c_wait(i2c);
240         if (result) {
241                 if (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT) == STAT_IDLE) {
242                         /*
243                          * Controller refused to send start flag May
244                          * be a client is holding SDA low - let's try
245                          * to free it.
246                          */
247                         octeon_i2c_unblock(i2c);
248                         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
249                                             TWSI_CTL_ENAB | TWSI_CTL_STA);
250
251                         result = octeon_i2c_wait(i2c);
252                 }
253                 if (result)
254                         return result;
255         }
256
257         data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
258         if ((data != STAT_START) && (data != STAT_RSTART)) {
259                 dev_err(i2c->dev, "%s: bad status (0x%x)\n", __func__, data);
260                 return -EIO;
261         }
262
263         return 0;
264 }
265
266 /**
267  * octeon_i2c_stop - send STOP to the bus.
268  * @i2c: The struct octeon_i2c.
269  *
270  * Returns 0 on success, otherwise a negative errno.
271  */
272 static int octeon_i2c_stop(struct octeon_i2c *i2c)
273 {
274         u8 data;
275
276         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
277                             TWSI_CTL_ENAB | TWSI_CTL_STP);
278
279         data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
280
281         if (data != STAT_IDLE) {
282                 dev_err(i2c->dev, "%s: bad status(0x%x)\n", __func__, data);
283                 return -EIO;
284         }
285         return 0;
286 }
287
288 /**
289  * octeon_i2c_write - send data to the bus.
290  * @i2c: The struct octeon_i2c.
291  * @target: Target address.
292  * @data: Pointer to the data to be sent.
293  * @length: Length of the data.
294  *
295  * The address is sent over the bus, then the data.
296  *
297  * Returns 0 on success, otherwise a negative errno.
298  */
299 static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
300                             const u8 *data, int length)
301 {
302         int i, result;
303         u8 tmp;
304
305         result = octeon_i2c_start(i2c);
306         if (result)
307                 return result;
308
309         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, target << 1);
310         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
311
312         result = octeon_i2c_wait(i2c);
313         if (result)
314                 return result;
315
316         for (i = 0; i < length; i++) {
317                 tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
318                 if ((tmp != STAT_TXADDR_ACK) && (tmp != STAT_TXDATA_ACK)) {
319                         dev_err(i2c->dev,
320                                 "%s: bad status before write (0x%x)\n",
321                                 __func__, tmp);
322                         return -EIO;
323                 }
324
325                 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, data[i]);
326                 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
327
328                 result = octeon_i2c_wait(i2c);
329                 if (result)
330                         return result;
331         }
332
333         return 0;
334 }
335
336 /**
337  * octeon_i2c_read - receive data from the bus.
338  * @i2c: The struct octeon_i2c.
339  * @target: Target address.
340  * @data: Pointer to the location to store the datae .
341  * @length: Length of the data.
342  *
343  * The address is sent over the bus, then the data is read.
344  *
345  * Returns 0 on success, otherwise a negative errno.
346  */
347 static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
348                            u8 *data, int length)
349 {
350         int i, result;
351         u8 tmp;
352
353         if (length < 1)
354                 return -EINVAL;
355
356         result = octeon_i2c_start(i2c);
357         if (result)
358                 return result;
359
360         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, (target<<1) | 1);
361         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
362
363         result = octeon_i2c_wait(i2c);
364         if (result)
365                 return result;
366
367         for (i = 0; i < length; i++) {
368                 tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
369                 if ((tmp != STAT_RXDATA_ACK) && (tmp != STAT_RXADDR_ACK)) {
370                         dev_err(i2c->dev,
371                                 "%s: bad status before read (0x%x)\n",
372                                 __func__, tmp);
373                         return -EIO;
374                 }
375
376                 if (i+1 < length)
377                         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
378                                                 TWSI_CTL_ENAB | TWSI_CTL_AAK);
379                 else
380                         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
381                                                 TWSI_CTL_ENAB);
382
383                 result = octeon_i2c_wait(i2c);
384                 if (result)
385                         return result;
386
387                 data[i] = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_DATA);
388         }
389         return 0;
390 }
391
392 /**
393  * octeon_i2c_xfer - The driver's master_xfer function.
394  * @adap: Pointer to the i2c_adapter structure.
395  * @msgs: Pointer to the messages to be processed.
396  * @num: Length of the MSGS array.
397  *
398  * Returns the number of messages processed, or a negative errno on
399  * failure.
400  */
401 static int octeon_i2c_xfer(struct i2c_adapter *adap,
402                            struct i2c_msg *msgs,
403                            int num)
404 {
405         struct i2c_msg *pmsg;
406         int i;
407         int ret = 0;
408         struct octeon_i2c *i2c = i2c_get_adapdata(adap);
409
410         for (i = 0; ret == 0 && i < num; i++) {
411                 pmsg = &msgs[i];
412                 dev_dbg(i2c->dev,
413                         "Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
414                          pmsg->flags & I2C_M_RD ? "read" : "write",
415                          pmsg->len, pmsg->addr, i + 1, num);
416                 if (pmsg->flags & I2C_M_RD)
417                         ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
418                                                 pmsg->len);
419                 else
420                         ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf,
421                                                 pmsg->len);
422         }
423         octeon_i2c_stop(i2c);
424
425         return (ret != 0) ? ret : num;
426 }
427
428 static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
429 {
430         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
431 }
432
433 static const struct i2c_algorithm octeon_i2c_algo = {
434         .master_xfer = octeon_i2c_xfer,
435         .functionality = octeon_i2c_functionality,
436 };
437
438 static struct i2c_adapter octeon_i2c_ops = {
439         .owner = THIS_MODULE,
440         .name = "OCTEON adapter",
441         .algo = &octeon_i2c_algo,
442         .timeout = HZ / 50,
443 };
444
445 /**
446  * octeon_i2c_setclock - Calculate and set clock divisors.
447  */
448 static int octeon_i2c_setclock(struct octeon_i2c *i2c)
449 {
450         int tclk, thp_base, inc, thp_idx, mdiv_idx, ndiv_idx, foscl, diff;
451         int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = 1000000;
452
453         for (ndiv_idx = 0; ndiv_idx < 8 && delta_hz != 0; ndiv_idx++) {
454                 /*
455                  * An mdiv value of less than 2 seems to not work well
456                  * with ds1337 RTCs, so we constrain it to larger
457                  * values.
458                  */
459                 for (mdiv_idx = 15; mdiv_idx >= 2 && delta_hz != 0; mdiv_idx--) {
460                         /*
461                          * For given ndiv and mdiv values check the
462                          * two closest thp values.
463                          */
464                         tclk = i2c->twsi_freq * (mdiv_idx + 1) * 10;
465                         tclk *= (1 << ndiv_idx);
466                         thp_base = (i2c->sys_freq / (tclk * 2)) - 1;
467                         for (inc = 0; inc <= 1; inc++) {
468                                 thp_idx = thp_base + inc;
469                                 if (thp_idx < 5 || thp_idx > 0xff)
470                                         continue;
471
472                                 foscl = i2c->sys_freq / (2 * (thp_idx + 1));
473                                 foscl = foscl / (1 << ndiv_idx);
474                                 foscl = foscl / (mdiv_idx + 1) / 10;
475                                 diff = abs(foscl - i2c->twsi_freq);
476                                 if (diff < delta_hz) {
477                                         delta_hz = diff;
478                                         thp = thp_idx;
479                                         mdiv = mdiv_idx;
480                                         ndiv = ndiv_idx;
481                                 }
482                         }
483                 }
484         }
485         octeon_i2c_write_sw(i2c, SW_TWSI_OP_TWSI_CLK, thp);
486         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CLKCTL, (mdiv << 3) | ndiv);
487
488         return 0;
489 }
490
491 static int octeon_i2c_initlowlevel(struct octeon_i2c *i2c)
492 {
493         u8 status;
494         int tries;
495
496         /* disable high level controller, enable bus access */
497         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
498
499         /* reset controller */
500         octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_RST, 0);
501
502         for (tries = 10; tries; tries--) {
503                 udelay(1);
504                 status = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
505                 if (status == STAT_IDLE)
506                         return 0;
507         }
508         dev_err(i2c->dev, "%s: TWSI_RST failed! (0x%x)\n", __func__, status);
509         return -EIO;
510 }
511
512 static int octeon_i2c_probe(struct platform_device *pdev)
513 {
514         int irq, result = 0;
515         struct octeon_i2c *i2c;
516         struct resource *res_mem;
517
518         /* All adaptors have an irq.  */
519         irq = platform_get_irq(pdev, 0);
520         if (irq < 0)
521                 return irq;
522
523         i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
524         if (!i2c) {
525                 dev_err(&pdev->dev, "kzalloc failed\n");
526                 result = -ENOMEM;
527                 goto out;
528         }
529         i2c->dev = &pdev->dev;
530
531         res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
532
533         if (res_mem == NULL) {
534                 dev_err(i2c->dev, "found no memory resource\n");
535                 result = -ENXIO;
536                 goto out;
537         }
538         i2c->twsi_phys = res_mem->start;
539         i2c->regsize = resource_size(res_mem);
540
541         /*
542          * "clock-rate" is a legacy binding, the official binding is
543          * "clock-frequency".  Try the official one first and then
544          * fall back if it doesn't exist.
545          */
546         if (of_property_read_u32(pdev->dev.of_node,
547                                  "clock-frequency", &i2c->twsi_freq) &&
548             of_property_read_u32(pdev->dev.of_node,
549                                  "clock-rate", &i2c->twsi_freq)) {
550                 dev_err(i2c->dev,
551                         "no I2C 'clock-rate' or 'clock-frequency' property\n");
552                 result = -ENXIO;
553                 goto out;
554         }
555
556         i2c->sys_freq = octeon_get_io_clock_rate();
557
558         if (!devm_request_mem_region(&pdev->dev, i2c->twsi_phys, i2c->regsize,
559                                       res_mem->name)) {
560                 dev_err(i2c->dev, "request_mem_region failed\n");
561                 goto out;
562         }
563         i2c->twsi_base = devm_ioremap(&pdev->dev, i2c->twsi_phys, i2c->regsize);
564
565         init_waitqueue_head(&i2c->queue);
566
567         i2c->irq = irq;
568
569         result = devm_request_irq(&pdev->dev, i2c->irq,
570                                   octeon_i2c_isr, 0, DRV_NAME, i2c);
571         if (result < 0) {
572                 dev_err(i2c->dev, "failed to attach interrupt\n");
573                 goto out;
574         }
575
576         result = octeon_i2c_initlowlevel(i2c);
577         if (result) {
578                 dev_err(i2c->dev, "init low level failed\n");
579                 goto  out;
580         }
581
582         result = octeon_i2c_setclock(i2c);
583         if (result) {
584                 dev_err(i2c->dev, "clock init failed\n");
585                 goto  out;
586         }
587
588         i2c->adap = octeon_i2c_ops;
589         i2c->adap.dev.parent = &pdev->dev;
590         i2c->adap.dev.of_node = pdev->dev.of_node;
591         i2c_set_adapdata(&i2c->adap, i2c);
592         platform_set_drvdata(pdev, i2c);
593
594         result = i2c_add_adapter(&i2c->adap);
595         if (result < 0) {
596                 dev_err(i2c->dev, "failed to add adapter\n");
597                 goto out;
598         }
599         dev_info(i2c->dev, "version %s\n", DRV_VERSION);
600
601         return 0;
602
603 out:
604         return result;
605 };
606
607 static int octeon_i2c_remove(struct platform_device *pdev)
608 {
609         struct octeon_i2c *i2c = platform_get_drvdata(pdev);
610
611         i2c_del_adapter(&i2c->adap);
612         return 0;
613 };
614
615 static struct of_device_id octeon_i2c_match[] = {
616         {
617                 .compatible = "cavium,octeon-3860-twsi",
618         },
619         {},
620 };
621 MODULE_DEVICE_TABLE(of, octeon_i2c_match);
622
623 static struct platform_driver octeon_i2c_driver = {
624         .probe          = octeon_i2c_probe,
625         .remove         = octeon_i2c_remove,
626         .driver         = {
627                 .owner  = THIS_MODULE,
628                 .name   = DRV_NAME,
629                 .of_match_table = octeon_i2c_match,
630         },
631 };
632
633 module_platform_driver(octeon_i2c_driver);
634
635 MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
636 MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
637 MODULE_LICENSE("GPL");
638 MODULE_VERSION(DRV_VERSION);