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1 /*
2 * (C) Copyright 2009-2010
3 * Nokia Siemens Networks, michael.lawnick.ext@nsn.com
4 *
5 * Portions Copyright (C) 2010 - 2016 Cavium, 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/i2c.h>
22 #include <linux/io.h>
23 #include <linux/of.h>
24
25 #include <asm/octeon/octeon.h>
26
27 #define DRV_NAME "i2c-octeon"
28
29 /* Register offsets */
30 #define SW_TWSI 0x00
31 #define TWSI_INT 0x10
32
33 /* Controller command patterns */
34 #define SW_TWSI_V BIT_ULL(63) /* Valid bit */
35 #define SW_TWSI_R BIT_ULL(56) /* Result or read bit */
36
37 /* Controller opcode word (bits 60:57) */
38 #define SW_TWSI_OP_SHIFT 57
39 #define SW_TWSI_OP_TWSI_CLK (4ULL << SW_TWSI_OP_SHIFT)
40 #define SW_TWSI_OP_EOP (6ULL << SW_TWSI_OP_SHIFT) /* Extended opcode */
41
42 /* Controller extended opcode word (bits 34:32) */
43 #define SW_TWSI_EOP_SHIFT 32
44 #define SW_TWSI_EOP_TWSI_DATA (SW_TWSI_OP_EOP | 1ULL << SW_TWSI_EOP_SHIFT)
45 #define SW_TWSI_EOP_TWSI_CTL (SW_TWSI_OP_EOP | 2ULL << SW_TWSI_EOP_SHIFT)
46 #define SW_TWSI_EOP_TWSI_CLKCTL (SW_TWSI_OP_EOP | 3ULL << SW_TWSI_EOP_SHIFT)
47 #define SW_TWSI_EOP_TWSI_STAT (SW_TWSI_OP_EOP | 3ULL << SW_TWSI_EOP_SHIFT)
48 #define SW_TWSI_EOP_TWSI_RST (SW_TWSI_OP_EOP | 7ULL << SW_TWSI_EOP_SHIFT)
49
50 /* Controller command and status bits */
51 #define TWSI_CTL_CE 0x80
52 #define TWSI_CTL_ENAB 0x40 /* Bus enable */
53 #define TWSI_CTL_STA 0x20 /* Master-mode start, HW clears when done */
54 #define TWSI_CTL_STP 0x10 /* Master-mode stop, HW clears when done */
55 #define TWSI_CTL_IFLG 0x08 /* HW event, SW writes 0 to ACK */
56 #define TWSI_CTL_AAK 0x04 /* Assert ACK */
57
58 /* Some status values */
59 #define STAT_START 0x08
60 #define STAT_RSTART 0x10
61 #define STAT_TXADDR_ACK 0x18
62 #define STAT_TXDATA_ACK 0x28
63 #define STAT_RXADDR_ACK 0x40
64 #define STAT_RXDATA_ACK 0x50
65 #define STAT_IDLE 0xF8
66
67 /* TWSI_INT values */
68 #define TWSI_INT_CORE_EN BIT_ULL(6)
69 #define TWSI_INT_SDA_OVR BIT_ULL(8)
70 #define TWSI_INT_SCL_OVR BIT_ULL(9)
71
72 struct octeon_i2c {
73 wait_queue_head_t queue;
74 struct i2c_adapter adap;
75 int irq;
76 u32 twsi_freq;
77 int sys_freq;
78 void __iomem *twsi_base;
79 struct device *dev;
80 };
81
82 /**
83 * octeon_i2c_write_sw - write an I2C core register
84 * @i2c: The struct octeon_i2c
85 * @eop_reg: Register selector
86 * @data: Value to be written
87 *
88 * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
89 */
90 static void octeon_i2c_write_sw(struct octeon_i2c *i2c, u64 eop_reg, u8 data)
91 {
92 u64 tmp;
93
94 __raw_writeq(SW_TWSI_V | eop_reg | data, i2c->twsi_base + SW_TWSI);
95 do {
96 tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
97 } while ((tmp & SW_TWSI_V) != 0);
98 }
99
100 /**
101 * octeon_i2c_read_sw - read lower bits of an I2C core register
102 * @i2c: The struct octeon_i2c
103 * @eop_reg: Register selector
104 *
105 * Returns the data.
106 *
107 * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
108 */
109 static u8 octeon_i2c_read_sw(struct octeon_i2c *i2c, u64 eop_reg)
110 {
111 u64 tmp;
112
113 __raw_writeq(SW_TWSI_V | eop_reg | SW_TWSI_R, i2c->twsi_base + SW_TWSI);
114 do {
115 tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
116 } while ((tmp & SW_TWSI_V) != 0);
117
118 return tmp & 0xFF;
119 }
120
121 /**
122 * octeon_i2c_write_int - write the TWSI_INT register
123 * @i2c: The struct octeon_i2c
124 * @data: Value to be written
125 */
126 static void octeon_i2c_write_int(struct octeon_i2c *i2c, u64 data)
127 {
128 __raw_writeq(data, i2c->twsi_base + TWSI_INT);
129 __raw_readq(i2c->twsi_base + TWSI_INT);
130 }
131
132 /**
133 * octeon_i2c_int_enable - enable the CORE interrupt
134 * @i2c: The struct octeon_i2c
135 *
136 * The interrupt will be asserted when there is non-STAT_IDLE state in
137 * the SW_TWSI_EOP_TWSI_STAT register.
138 */
139 static void octeon_i2c_int_enable(struct octeon_i2c *i2c)
140 {
141 octeon_i2c_write_int(i2c, TWSI_INT_CORE_EN);
142 }
143
144 /* disable the CORE interrupt */
145 static void octeon_i2c_int_disable(struct octeon_i2c *i2c)
146 {
147 /* clear TS/ST/IFLG events */
148 octeon_i2c_write_int(i2c, 0);
149 }
150
151 /**
152 * octeon_i2c_unblock - unblock the bus
153 * @i2c: The struct octeon_i2c
154 *
155 * If there was a reset while a device was driving 0 to bus, bus is blocked.
156 * We toggle it free manually by some clock 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
164 for (i = 0; i < 9; i++) {
165 octeon_i2c_write_int(i2c, 0);
166 udelay(5);
167 octeon_i2c_write_int(i2c, TWSI_INT_SCL_OVR);
168 udelay(5);
169 }
170 /* hand-crank a STOP */
171 octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR | TWSI_INT_SCL_OVR);
172 udelay(5);
173 octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR);
174 udelay(5);
175 octeon_i2c_write_int(i2c, 0);
176 }
177
178 /* interrupt service routine */
179 static irqreturn_t octeon_i2c_isr(int irq, void *dev_id)
180 {
181 struct octeon_i2c *i2c = dev_id;
182
183 octeon_i2c_int_disable(i2c);
184 wake_up(&i2c->queue);
185
186 return IRQ_HANDLED;
187 }
188
189
190 static int octeon_i2c_test_iflg(struct octeon_i2c *i2c)
191 {
192 return (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_CTL) & TWSI_CTL_IFLG) != 0;
193 }
194
195 /**
196 * octeon_i2c_wait - wait for the IFLG to be set
197 * @i2c: The struct octeon_i2c
198 *
199 * Returns 0 on success, otherwise a negative errno.
200 */
201 static int octeon_i2c_wait(struct octeon_i2c *i2c)
202 {
203 long time_left;
204
205 octeon_i2c_int_enable(i2c);
206 time_left = wait_event_timeout(i2c->queue, octeon_i2c_test_iflg(i2c),
207 i2c->adap.timeout);
208 octeon_i2c_int_disable(i2c);
209 if (!time_left) {
210 dev_dbg(i2c->dev, "%s: timeout\n", __func__);
211 return -ETIMEDOUT;
212 }
213
214 return 0;
215 }
216
217 /**
218 * octeon_i2c_start - send START to the bus
219 * @i2c: The struct octeon_i2c
220 *
221 * Returns 0 on success, otherwise a negative errno.
222 */
223 static int octeon_i2c_start(struct octeon_i2c *i2c)
224 {
225 int result;
226 u8 data;
227
228 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
229 TWSI_CTL_ENAB | TWSI_CTL_STA);
230
231 result = octeon_i2c_wait(i2c);
232 if (result) {
233 if (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT) == STAT_IDLE) {
234 /*
235 * Controller refused to send start flag May
236 * be a client is holding SDA low - let's try
237 * to free it.
238 */
239 octeon_i2c_unblock(i2c);
240 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
241 TWSI_CTL_ENAB | TWSI_CTL_STA);
242 result = octeon_i2c_wait(i2c);
243 }
244 if (result)
245 return result;
246 }
247
248 data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
249 if ((data != STAT_START) && (data != STAT_RSTART)) {
250 dev_err(i2c->dev, "%s: bad status (0x%x)\n", __func__, data);
251 return -EIO;
252 }
253
254 return 0;
255 }
256
257 /* send STOP to the bus */
258 static void octeon_i2c_stop(struct octeon_i2c *i2c)
259 {
260 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
261 TWSI_CTL_ENAB | TWSI_CTL_STP);
262 }
263
264 /**
265 * octeon_i2c_write - send data to the bus via low-level controller
266 * @i2c: The struct octeon_i2c
267 * @target: Target address
268 * @data: Pointer to the data to be sent
269 * @length: Length of the data
270 *
271 * The address is sent over the bus, then the data.
272 *
273 * Returns 0 on success, otherwise a negative errno.
274 */
275 static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
276 const u8 *data, int length)
277 {
278 int i, result;
279 u8 tmp;
280
281 result = octeon_i2c_start(i2c);
282 if (result)
283 return result;
284
285 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, target << 1);
286 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
287
288 result = octeon_i2c_wait(i2c);
289 if (result)
290 return result;
291
292 for (i = 0; i < length; i++) {
293 tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
294
295 if ((tmp != STAT_TXADDR_ACK) && (tmp != STAT_TXDATA_ACK)) {
296 dev_err(i2c->dev,
297 "%s: bad status before write (0x%x)\n",
298 __func__, tmp);
299 return -EIO;
300 }
301
302 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, data[i]);
303 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
304
305 result = octeon_i2c_wait(i2c);
306 if (result)
307 return result;
308 }
309
310 return 0;
311 }
312
313 /**
314 * octeon_i2c_read - receive data from the bus via low-level controller
315 * @i2c: The struct octeon_i2c
316 * @target: Target address
317 * @data: Pointer to the location to store the data
318 * @rlength: Length of the data
319 * @recv_len: flag for length byte
320 *
321 * The address is sent over the bus, then the data is read.
322 *
323 * Returns 0 on success, otherwise a negative errno.
324 */
325 static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
326 u8 *data, u16 *rlength, bool recv_len)
327 {
328 int i, result, length = *rlength;
329 u8 tmp;
330
331 if (length < 1)
332 return -EINVAL;
333
334 result = octeon_i2c_start(i2c);
335 if (result)
336 return result;
337
338 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, (target << 1) | 1);
339 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
340
341 result = octeon_i2c_wait(i2c);
342 if (result)
343 return result;
344
345 for (i = 0; i < length; i++) {
346 tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
347
348 if ((tmp != STAT_RXDATA_ACK) && (tmp != STAT_RXADDR_ACK)) {
349 dev_err(i2c->dev,
350 "%s: bad status before read (0x%x)\n",
351 __func__, tmp);
352 return -EIO;
353 }
354
355 if (i + 1 < length)
356 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
357 TWSI_CTL_ENAB | TWSI_CTL_AAK);
358 else
359 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
360 TWSI_CTL_ENAB);
361
362 result = octeon_i2c_wait(i2c);
363 if (result)
364 return result;
365
366 data[i] = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_DATA);
367 if (recv_len && i == 0) {
368 if (data[i] > I2C_SMBUS_BLOCK_MAX + 1) {
369 dev_err(i2c->dev,
370 "%s: read len > I2C_SMBUS_BLOCK_MAX %d\n",
371 __func__, data[i]);
372 return -EPROTO;
373 }
374 length += data[i];
375 }
376 }
377 *rlength = length;
378 return 0;
379 }
380
381 /**
382 * octeon_i2c_xfer - The driver's master_xfer function
383 * @adap: Pointer to the i2c_adapter structure
384 * @msgs: Pointer to the messages to be processed
385 * @num: Length of the MSGS array
386 *
387 * Returns the number of messages processed, or a negative errno on failure.
388 */
389 static int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
390 int num)
391 {
392 struct octeon_i2c *i2c = i2c_get_adapdata(adap);
393 int i, ret = 0;
394
395 for (i = 0; ret == 0 && i < num; i++) {
396 struct i2c_msg *pmsg = &msgs[i];
397
398 dev_dbg(i2c->dev,
399 "Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
400 pmsg->flags & I2C_M_RD ? "read" : "write",
401 pmsg->len, pmsg->addr, i + 1, num);
402 if (pmsg->flags & I2C_M_RD)
403 ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
404 &pmsg->len, pmsg->flags & I2C_M_RECV_LEN);
405 else
406 ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf,
407 pmsg->len);
408 }
409 octeon_i2c_stop(i2c);
410
411 return (ret != 0) ? ret : num;
412 }
413
414 static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
415 {
416 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
417 I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_SMBUS_BLOCK_PROC_CALL;
418 }
419
420 static const struct i2c_algorithm octeon_i2c_algo = {
421 .master_xfer = octeon_i2c_xfer,
422 .functionality = octeon_i2c_functionality,
423 };
424
425 static struct i2c_adapter octeon_i2c_ops = {
426 .owner = THIS_MODULE,
427 .name = "OCTEON adapter",
428 .algo = &octeon_i2c_algo,
429 .timeout = HZ / 50,
430 };
431
432 /* calculate and set clock divisors */
433 static void octeon_i2c_set_clock(struct octeon_i2c *i2c)
434 {
435 int tclk, thp_base, inc, thp_idx, mdiv_idx, ndiv_idx, foscl, diff;
436 int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = 1000000;
437
438 for (ndiv_idx = 0; ndiv_idx < 8 && delta_hz != 0; ndiv_idx++) {
439 /*
440 * An mdiv value of less than 2 seems to not work well
441 * with ds1337 RTCs, so we constrain it to larger values.
442 */
443 for (mdiv_idx = 15; mdiv_idx >= 2 && delta_hz != 0; mdiv_idx--) {
444 /*
445 * For given ndiv and mdiv values check the
446 * two closest thp values.
447 */
448 tclk = i2c->twsi_freq * (mdiv_idx + 1) * 10;
449 tclk *= (1 << ndiv_idx);
450 thp_base = (i2c->sys_freq / (tclk * 2)) - 1;
451
452 for (inc = 0; inc <= 1; inc++) {
453 thp_idx = thp_base + inc;
454 if (thp_idx < 5 || thp_idx > 0xff)
455 continue;
456
457 foscl = i2c->sys_freq / (2 * (thp_idx + 1));
458 foscl = foscl / (1 << ndiv_idx);
459 foscl = foscl / (mdiv_idx + 1) / 10;
460 diff = abs(foscl - i2c->twsi_freq);
461 if (diff < delta_hz) {
462 delta_hz = diff;
463 thp = thp_idx;
464 mdiv = mdiv_idx;
465 ndiv = ndiv_idx;
466 }
467 }
468 }
469 }
470 octeon_i2c_write_sw(i2c, SW_TWSI_OP_TWSI_CLK, thp);
471 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CLKCTL, (mdiv << 3) | ndiv);
472 }
473
474 static int octeon_i2c_init_lowlevel(struct octeon_i2c *i2c)
475 {
476 u8 status;
477 int tries;
478
479 /* disable high level controller, enable bus access */
480 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
481
482 /* reset controller */
483 octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_RST, 0);
484
485 for (tries = 10; tries; tries--) {
486 udelay(1);
487 status = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
488 if (status == STAT_IDLE)
489 return 0;
490 }
491 dev_err(i2c->dev, "%s: TWSI_RST failed! (0x%x)\n", __func__, status);
492 return -EIO;
493 }
494
495 static int octeon_i2c_probe(struct platform_device *pdev)
496 {
497 struct device_node *node = pdev->dev.of_node;
498 struct resource *res_mem;
499 struct octeon_i2c *i2c;
500 int irq, result = 0;
501
502 /* All adaptors have an irq. */
503 irq = platform_get_irq(pdev, 0);
504 if (irq < 0)
505 return irq;
506
507 i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
508 if (!i2c) {
509 result = -ENOMEM;
510 goto out;
511 }
512 i2c->dev = &pdev->dev;
513
514 res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
515 i2c->twsi_base = devm_ioremap_resource(&pdev->dev, res_mem);
516 if (IS_ERR(i2c->twsi_base)) {
517 result = PTR_ERR(i2c->twsi_base);
518 goto out;
519 }
520
521 /*
522 * "clock-rate" is a legacy binding, the official binding is
523 * "clock-frequency". Try the official one first and then
524 * fall back if it doesn't exist.
525 */
526 if (of_property_read_u32(node, "clock-frequency", &i2c->twsi_freq) &&
527 of_property_read_u32(node, "clock-rate", &i2c->twsi_freq)) {
528 dev_err(i2c->dev,
529 "no I2C 'clock-rate' or 'clock-frequency' property\n");
530 result = -ENXIO;
531 goto out;
532 }
533
534 i2c->sys_freq = octeon_get_io_clock_rate();
535
536 init_waitqueue_head(&i2c->queue);
537
538 i2c->irq = irq;
539
540 result = devm_request_irq(&pdev->dev, i2c->irq,
541 octeon_i2c_isr, 0, DRV_NAME, i2c);
542 if (result < 0) {
543 dev_err(i2c->dev, "failed to attach interrupt\n");
544 goto out;
545 }
546
547 result = octeon_i2c_init_lowlevel(i2c);
548 if (result) {
549 dev_err(i2c->dev, "init low level failed\n");
550 goto out;
551 }
552
553 octeon_i2c_set_clock(i2c);
554
555 i2c->adap = octeon_i2c_ops;
556 i2c->adap.dev.parent = &pdev->dev;
557 i2c->adap.dev.of_node = node;
558 i2c_set_adapdata(&i2c->adap, i2c);
559 platform_set_drvdata(pdev, i2c);
560
561 result = i2c_add_adapter(&i2c->adap);
562 if (result < 0) {
563 dev_err(i2c->dev, "failed to add adapter\n");
564 goto out;
565 }
566 dev_info(i2c->dev, "probed\n");
567 return 0;
568
569 out:
570 return result;
571 };
572
573 static int octeon_i2c_remove(struct platform_device *pdev)
574 {
575 struct octeon_i2c *i2c = platform_get_drvdata(pdev);
576
577 i2c_del_adapter(&i2c->adap);
578 return 0;
579 };
580
581 static const struct of_device_id octeon_i2c_match[] = {
582 { .compatible = "cavium,octeon-3860-twsi", },
583 {},
584 };
585 MODULE_DEVICE_TABLE(of, octeon_i2c_match);
586
587 static struct platform_driver octeon_i2c_driver = {
588 .probe = octeon_i2c_probe,
589 .remove = octeon_i2c_remove,
590 .driver = {
591 .name = DRV_NAME,
592 .of_match_table = octeon_i2c_match,
593 },
594 };
595
596 module_platform_driver(octeon_i2c_driver);
597
598 MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
599 MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
600 MODULE_LICENSE("GPL");