Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc
[linux-2.6-block.git] / 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 - 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");