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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Renesas RIIC driver
4 *
5 * Copyright (C) 2013 Wolfram Sang <wsa@sang-engineering.com>
6 * Copyright (C) 2013 Renesas Solutions Corp.
7 */
8
9/*
10 * This i2c core has a lot of interrupts, namely 8. We use their chaining as
11 * some kind of state machine.
12 *
13 * 1) The main xfer routine kicks off a transmission by putting the start bit
14 * (or repeated start) on the bus and enabling the transmit interrupt (TIE)
15 * since we need to send the target address + RW bit in every case.
16 *
17 * 2) TIE sends target address + RW bit and selects how to continue.
18 *
19 * 3a) Write case: We keep utilizing TIE as long as we have data to send. If we
20 * are done, we switch over to the transmission done interrupt (TEIE) and mark
21 * the message as completed (includes sending STOP) there.
22 *
23 * 3b) Read case: We switch over to receive interrupt (RIE). One dummy read is
24 * needed to start clocking, then we keep receiving until we are done. Note
25 * that we use the RDRFS mode all the time, i.e. we ACK/NACK every byte by
26 * writing to the ACKBT bit. I tried using the RDRFS mode only at the end of a
27 * message to create the final NACK as sketched in the datasheet. This caused
28 * some subtle races (when byte n was processed and byte n+1 was already
29 * waiting), though, and I started with the safe approach.
30 *
31 * 4) If we got a NACK somewhere, we flag the error and stop the transmission
32 * via NAKIE.
33 *
34 * Also check the comments in the interrupt routines for some gory details.
35 */
36
37#include <linux/clk.h>
38#include <linux/completion.h>
39#include <linux/err.h>
40#include <linux/i2c.h>
41#include <linux/interrupt.h>
42#include <linux/io.h>
43#include <linux/module.h>
44#include <linux/of.h>
45#include <linux/platform_device.h>
46#include <linux/pm_runtime.h>
47#include <linux/reset.h>
48
49#define ICCR1_ICE 0x80
50#define ICCR1_IICRST 0x40
51#define ICCR1_SOWP 0x10
52
53#define ICCR2_BBSY 0x80
54#define ICCR2_SP 0x08
55#define ICCR2_RS 0x04
56#define ICCR2_ST 0x02
57
58#define ICMR1_CKS_MASK 0x70
59#define ICMR1_BCWP 0x08
60#define ICMR1_CKS(_x) ((((_x) << 4) & ICMR1_CKS_MASK) | ICMR1_BCWP)
61
62#define ICMR3_RDRFS 0x20
63#define ICMR3_ACKWP 0x10
64#define ICMR3_ACKBT 0x08
65
66#define ICFER_FMPE 0x80
67
68#define ICIER_TIE 0x80
69#define ICIER_TEIE 0x40
70#define ICIER_RIE 0x20
71#define ICIER_NAKIE 0x10
72#define ICIER_SPIE 0x08
73
74#define ICSR2_NACKF 0x10
75
76#define ICBR_RESERVED 0xe0 /* Should be 1 on writes */
77
78#define RIIC_INIT_MSG -1
79
80enum riic_reg_list {
81 RIIC_ICCR1 = 0,
82 RIIC_ICCR2,
83 RIIC_ICMR1,
84 RIIC_ICMR3,
85 RIIC_ICFER,
86 RIIC_ICSER,
87 RIIC_ICIER,
88 RIIC_ICSR2,
89 RIIC_ICBRL,
90 RIIC_ICBRH,
91 RIIC_ICDRT,
92 RIIC_ICDRR,
93 RIIC_REG_END,
94};
95
96struct riic_of_data {
97 const u8 *regs;
98 bool fast_mode_plus;
99};
100
101struct riic_dev {
102 void __iomem *base;
103 u8 *buf;
104 struct i2c_msg *msg;
105 int bytes_left;
106 int err;
107 int is_last;
108 const struct riic_of_data *info;
109 struct completion msg_done;
110 struct i2c_adapter adapter;
111 struct clk *clk;
112 struct reset_control *rstc;
113 struct i2c_timings i2c_t;
114};
115
116struct riic_irq_desc {
117 int res_num;
118 irq_handler_t isr;
119 char *name;
120};
121
122static inline void riic_writeb(struct riic_dev *riic, u8 val, u8 offset)
123{
124 writeb(val, riic->base + riic->info->regs[offset]);
125}
126
127static inline u8 riic_readb(struct riic_dev *riic, u8 offset)
128{
129 return readb(riic->base + riic->info->regs[offset]);
130}
131
132static inline void riic_clear_set_bit(struct riic_dev *riic, u8 clear, u8 set, u8 reg)
133{
134 riic_writeb(riic, (riic_readb(riic, reg) & ~clear) | set, reg);
135}
136
137static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
138{
139 struct riic_dev *riic = i2c_get_adapdata(adap);
140 struct device *dev = adap->dev.parent;
141 unsigned long time_left;
142 int i, ret;
143 u8 start_bit;
144
145 ret = pm_runtime_resume_and_get(dev);
146 if (ret)
147 return ret;
148
149 if (riic_readb(riic, RIIC_ICCR2) & ICCR2_BBSY) {
150 riic->err = -EBUSY;
151 goto out;
152 }
153
154 reinit_completion(&riic->msg_done);
155 riic->err = 0;
156
157 riic_writeb(riic, 0, RIIC_ICSR2);
158
159 for (i = 0, start_bit = ICCR2_ST; i < num; i++) {
160 riic->bytes_left = RIIC_INIT_MSG;
161 riic->buf = msgs[i].buf;
162 riic->msg = &msgs[i];
163 riic->is_last = (i == num - 1);
164
165 riic_writeb(riic, ICIER_NAKIE | ICIER_TIE, RIIC_ICIER);
166
167 riic_writeb(riic, start_bit, RIIC_ICCR2);
168
169 time_left = wait_for_completion_timeout(&riic->msg_done, riic->adapter.timeout);
170 if (time_left == 0)
171 riic->err = -ETIMEDOUT;
172
173 if (riic->err)
174 break;
175
176 start_bit = ICCR2_RS;
177 }
178
179 out:
180 pm_runtime_mark_last_busy(dev);
181 pm_runtime_put_autosuspend(dev);
182
183 return riic->err ?: num;
184}
185
186static irqreturn_t riic_tdre_isr(int irq, void *data)
187{
188 struct riic_dev *riic = data;
189 u8 val;
190
191 if (!riic->bytes_left)
192 return IRQ_NONE;
193
194 if (riic->bytes_left == RIIC_INIT_MSG) {
195 if (riic->msg->flags & I2C_M_RD)
196 /* On read, switch over to receive interrupt */
197 riic_clear_set_bit(riic, ICIER_TIE, ICIER_RIE, RIIC_ICIER);
198 else
199 /* On write, initialize length */
200 riic->bytes_left = riic->msg->len;
201
202 val = i2c_8bit_addr_from_msg(riic->msg);
203 } else {
204 val = *riic->buf;
205 riic->buf++;
206 riic->bytes_left--;
207 }
208
209 /*
210 * Switch to transmission ended interrupt when done. Do check here
211 * after bytes_left was initialized to support SMBUS_QUICK (new msg has
212 * 0 length then)
213 */
214 if (riic->bytes_left == 0)
215 riic_clear_set_bit(riic, ICIER_TIE, ICIER_TEIE, RIIC_ICIER);
216
217 /*
218 * This acks the TIE interrupt. We get another TIE immediately if our
219 * value could be moved to the shadow shift register right away. So
220 * this must be after updates to ICIER (where we want to disable TIE)!
221 */
222 riic_writeb(riic, val, RIIC_ICDRT);
223
224 return IRQ_HANDLED;
225}
226
227static irqreturn_t riic_tend_isr(int irq, void *data)
228{
229 struct riic_dev *riic = data;
230
231 if (riic_readb(riic, RIIC_ICSR2) & ICSR2_NACKF) {
232 /* We got a NACKIE */
233 riic_readb(riic, RIIC_ICDRR); /* dummy read */
234 riic_clear_set_bit(riic, ICSR2_NACKF, 0, RIIC_ICSR2);
235 riic->err = -ENXIO;
236 } else if (riic->bytes_left) {
237 return IRQ_NONE;
238 }
239
240 if (riic->is_last || riic->err) {
241 riic_clear_set_bit(riic, ICIER_TEIE, ICIER_SPIE, RIIC_ICIER);
242 riic_writeb(riic, ICCR2_SP, RIIC_ICCR2);
243 } else {
244 /* Transfer is complete, but do not send STOP */
245 riic_clear_set_bit(riic, ICIER_TEIE, 0, RIIC_ICIER);
246 complete(&riic->msg_done);
247 }
248
249 return IRQ_HANDLED;
250}
251
252static irqreturn_t riic_rdrf_isr(int irq, void *data)
253{
254 struct riic_dev *riic = data;
255
256 if (!riic->bytes_left)
257 return IRQ_NONE;
258
259 if (riic->bytes_left == RIIC_INIT_MSG) {
260 riic->bytes_left = riic->msg->len;
261 riic_readb(riic, RIIC_ICDRR); /* dummy read */
262 return IRQ_HANDLED;
263 }
264
265 if (riic->bytes_left == 1) {
266 /* STOP must come before we set ACKBT! */
267 if (riic->is_last) {
268 riic_clear_set_bit(riic, 0, ICIER_SPIE, RIIC_ICIER);
269 riic_writeb(riic, ICCR2_SP, RIIC_ICCR2);
270 }
271
272 riic_clear_set_bit(riic, 0, ICMR3_ACKBT, RIIC_ICMR3);
273
274 } else {
275 riic_clear_set_bit(riic, ICMR3_ACKBT, 0, RIIC_ICMR3);
276 }
277
278 /* Reading acks the RIE interrupt */
279 *riic->buf = riic_readb(riic, RIIC_ICDRR);
280 riic->buf++;
281 riic->bytes_left--;
282
283 return IRQ_HANDLED;
284}
285
286static irqreturn_t riic_stop_isr(int irq, void *data)
287{
288 struct riic_dev *riic = data;
289
290 /* read back registers to confirm writes have fully propagated */
291 riic_writeb(riic, 0, RIIC_ICSR2);
292 riic_readb(riic, RIIC_ICSR2);
293 riic_writeb(riic, 0, RIIC_ICIER);
294 riic_readb(riic, RIIC_ICIER);
295
296 complete(&riic->msg_done);
297
298 return IRQ_HANDLED;
299}
300
301static u32 riic_func(struct i2c_adapter *adap)
302{
303 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
304}
305
306static const struct i2c_algorithm riic_algo = {
307 .xfer = riic_xfer,
308 .functionality = riic_func,
309};
310
311static int riic_init_hw(struct riic_dev *riic)
312{
313 int ret;
314 unsigned long rate;
315 int total_ticks, cks, brl, brh;
316 struct i2c_timings *t = &riic->i2c_t;
317 struct device *dev = riic->adapter.dev.parent;
318 bool fast_mode_plus = riic->info->fast_mode_plus;
319 u32 max_freq = fast_mode_plus ? I2C_MAX_FAST_MODE_PLUS_FREQ
320 : I2C_MAX_FAST_MODE_FREQ;
321
322 if (t->bus_freq_hz > max_freq)
323 return dev_err_probe(&riic->adapter.dev, -EINVAL,
324 "unsupported bus speed %uHz (%u max)\n",
325 t->bus_freq_hz, max_freq);
326
327 rate = clk_get_rate(riic->clk);
328
329 /*
330 * Assume the default register settings:
331 * FER.SCLE = 1 (SCL sync circuit enabled, adds 2 or 3 cycles)
332 * FER.NFE = 1 (noise circuit enabled)
333 * MR3.NF = 0 (1 cycle of noise filtered out)
334 *
335 * Freq (CKS=000) = (I2CCLK + tr + tf)/ (BRH + 3 + 1) + (BRL + 3 + 1)
336 * Freq (CKS!=000) = (I2CCLK + tr + tf)/ (BRH + 2 + 1) + (BRL + 2 + 1)
337 */
338
339 /*
340 * Determine reference clock rate. We must be able to get the desired
341 * frequency with only 62 clock ticks max (31 high, 31 low).
342 * Aim for a duty of 60% LOW, 40% HIGH.
343 */
344 total_ticks = DIV_ROUND_UP(rate, t->bus_freq_hz ?: 1);
345
346 for (cks = 0; cks < 7; cks++) {
347 /*
348 * 60% low time must be less than BRL + 2 + 1
349 * BRL max register value is 0x1F.
350 */
351 brl = ((total_ticks * 6) / 10);
352 if (brl <= (0x1F + 3))
353 break;
354
355 total_ticks = DIV_ROUND_UP(total_ticks, 2);
356 rate /= 2;
357 }
358
359 if (brl > (0x1F + 3)) {
360 dev_err(&riic->adapter.dev, "invalid speed (%lu). Too slow.\n",
361 (unsigned long)t->bus_freq_hz);
362 return -EINVAL;
363 }
364
365 brh = total_ticks - brl;
366
367 /* Remove automatic clock ticks for sync circuit and NF */
368 if (cks == 0) {
369 brl -= 4;
370 brh -= 4;
371 } else {
372 brl -= 3;
373 brh -= 3;
374 }
375
376 /*
377 * Remove clock ticks for rise and fall times. Convert ns to clock
378 * ticks.
379 */
380 brl -= t->scl_fall_ns / (1000000000 / rate);
381 brh -= t->scl_rise_ns / (1000000000 / rate);
382
383 /* Adjust for min register values for when SCLE=1 and NFE=1 */
384 if (brl < 1)
385 brl = 1;
386 if (brh < 1)
387 brh = 1;
388
389 pr_debug("i2c-riic: freq=%lu, duty=%d, fall=%lu, rise=%lu, cks=%d, brl=%d, brh=%d\n",
390 rate / total_ticks, ((brl + 3) * 100) / (brl + brh + 6),
391 t->scl_fall_ns / (1000000000 / rate),
392 t->scl_rise_ns / (1000000000 / rate), cks, brl, brh);
393
394 ret = pm_runtime_resume_and_get(dev);
395 if (ret)
396 return ret;
397
398 /* Changing the order of accessing IICRST and ICE may break things! */
399 riic_writeb(riic, ICCR1_IICRST | ICCR1_SOWP, RIIC_ICCR1);
400 riic_clear_set_bit(riic, 0, ICCR1_ICE, RIIC_ICCR1);
401
402 riic_writeb(riic, ICMR1_CKS(cks), RIIC_ICMR1);
403 riic_writeb(riic, brh | ICBR_RESERVED, RIIC_ICBRH);
404 riic_writeb(riic, brl | ICBR_RESERVED, RIIC_ICBRL);
405
406 riic_writeb(riic, 0, RIIC_ICSER);
407 riic_writeb(riic, ICMR3_ACKWP | ICMR3_RDRFS, RIIC_ICMR3);
408
409 if (fast_mode_plus && t->bus_freq_hz > I2C_MAX_FAST_MODE_FREQ)
410 riic_clear_set_bit(riic, 0, ICFER_FMPE, RIIC_ICFER);
411
412 riic_clear_set_bit(riic, ICCR1_IICRST, 0, RIIC_ICCR1);
413
414 pm_runtime_mark_last_busy(dev);
415 pm_runtime_put_autosuspend(dev);
416 return 0;
417}
418
419static struct riic_irq_desc riic_irqs[] = {
420 { .res_num = 0, .isr = riic_tend_isr, .name = "riic-tend" },
421 { .res_num = 1, .isr = riic_rdrf_isr, .name = "riic-rdrf" },
422 { .res_num = 2, .isr = riic_tdre_isr, .name = "riic-tdre" },
423 { .res_num = 3, .isr = riic_stop_isr, .name = "riic-stop" },
424 { .res_num = 5, .isr = riic_tend_isr, .name = "riic-nack" },
425};
426
427static void riic_reset_control_assert(void *data)
428{
429 reset_control_assert(data);
430}
431
432static int riic_i2c_probe(struct platform_device *pdev)
433{
434 struct device *dev = &pdev->dev;
435 struct riic_dev *riic;
436 struct i2c_adapter *adap;
437 int i, ret;
438
439 riic = devm_kzalloc(dev, sizeof(*riic), GFP_KERNEL);
440 if (!riic)
441 return -ENOMEM;
442
443 riic->base = devm_platform_ioremap_resource(pdev, 0);
444 if (IS_ERR(riic->base))
445 return PTR_ERR(riic->base);
446
447 riic->clk = devm_clk_get(dev, NULL);
448 if (IS_ERR(riic->clk)) {
449 dev_err(dev, "missing controller clock");
450 return PTR_ERR(riic->clk);
451 }
452
453 riic->rstc = devm_reset_control_get_optional_exclusive(dev, NULL);
454 if (IS_ERR(riic->rstc))
455 return dev_err_probe(dev, PTR_ERR(riic->rstc),
456 "Error: missing reset ctrl\n");
457
458 ret = reset_control_deassert(riic->rstc);
459 if (ret)
460 return ret;
461
462 ret = devm_add_action_or_reset(dev, riic_reset_control_assert, riic->rstc);
463 if (ret)
464 return ret;
465
466 for (i = 0; i < ARRAY_SIZE(riic_irqs); i++) {
467 ret = platform_get_irq(pdev, riic_irqs[i].res_num);
468 if (ret < 0)
469 return ret;
470
471 ret = devm_request_irq(dev, ret, riic_irqs[i].isr,
472 0, riic_irqs[i].name, riic);
473 if (ret) {
474 dev_err(dev, "failed to request irq %s\n", riic_irqs[i].name);
475 return ret;
476 }
477 }
478
479 riic->info = of_device_get_match_data(dev);
480
481 adap = &riic->adapter;
482 i2c_set_adapdata(adap, riic);
483 strscpy(adap->name, "Renesas RIIC adapter", sizeof(adap->name));
484 adap->owner = THIS_MODULE;
485 adap->algo = &riic_algo;
486 adap->dev.parent = dev;
487 adap->dev.of_node = dev->of_node;
488
489 init_completion(&riic->msg_done);
490
491 i2c_parse_fw_timings(dev, &riic->i2c_t, true);
492
493 /* Default 0 to save power. Can be overridden via sysfs for lower latency. */
494 pm_runtime_set_autosuspend_delay(dev, 0);
495 pm_runtime_use_autosuspend(dev);
496 pm_runtime_enable(dev);
497
498 ret = riic_init_hw(riic);
499 if (ret)
500 goto out;
501
502 ret = i2c_add_adapter(adap);
503 if (ret)
504 goto out;
505
506 platform_set_drvdata(pdev, riic);
507
508 dev_info(dev, "registered with %dHz bus speed\n", riic->i2c_t.bus_freq_hz);
509 return 0;
510
511out:
512 pm_runtime_disable(dev);
513 pm_runtime_dont_use_autosuspend(dev);
514 return ret;
515}
516
517static void riic_i2c_remove(struct platform_device *pdev)
518{
519 struct riic_dev *riic = platform_get_drvdata(pdev);
520 struct device *dev = &pdev->dev;
521 int ret;
522
523 ret = pm_runtime_resume_and_get(dev);
524 if (!ret) {
525 riic_writeb(riic, 0, RIIC_ICIER);
526 pm_runtime_put(dev);
527 }
528 i2c_del_adapter(&riic->adapter);
529 pm_runtime_disable(dev);
530 pm_runtime_dont_use_autosuspend(dev);
531}
532
533static const u8 riic_rz_a_regs[RIIC_REG_END] = {
534 [RIIC_ICCR1] = 0x00,
535 [RIIC_ICCR2] = 0x04,
536 [RIIC_ICMR1] = 0x08,
537 [RIIC_ICMR3] = 0x10,
538 [RIIC_ICFER] = 0x14,
539 [RIIC_ICSER] = 0x18,
540 [RIIC_ICIER] = 0x1c,
541 [RIIC_ICSR2] = 0x24,
542 [RIIC_ICBRL] = 0x34,
543 [RIIC_ICBRH] = 0x38,
544 [RIIC_ICDRT] = 0x3c,
545 [RIIC_ICDRR] = 0x40,
546};
547
548static const struct riic_of_data riic_rz_a_info = {
549 .regs = riic_rz_a_regs,
550 .fast_mode_plus = true,
551};
552
553static const struct riic_of_data riic_rz_a1h_info = {
554 .regs = riic_rz_a_regs,
555};
556
557static const u8 riic_rz_v2h_regs[RIIC_REG_END] = {
558 [RIIC_ICCR1] = 0x00,
559 [RIIC_ICCR2] = 0x01,
560 [RIIC_ICMR1] = 0x02,
561 [RIIC_ICMR3] = 0x04,
562 [RIIC_ICFER] = 0x05,
563 [RIIC_ICSER] = 0x06,
564 [RIIC_ICIER] = 0x07,
565 [RIIC_ICSR2] = 0x09,
566 [RIIC_ICBRL] = 0x10,
567 [RIIC_ICBRH] = 0x11,
568 [RIIC_ICDRT] = 0x12,
569 [RIIC_ICDRR] = 0x13,
570};
571
572static const struct riic_of_data riic_rz_v2h_info = {
573 .regs = riic_rz_v2h_regs,
574 .fast_mode_plus = true,
575};
576
577static int riic_i2c_suspend(struct device *dev)
578{
579 struct riic_dev *riic = dev_get_drvdata(dev);
580 int ret;
581
582 ret = pm_runtime_resume_and_get(dev);
583 if (ret)
584 return ret;
585
586 i2c_mark_adapter_suspended(&riic->adapter);
587
588 /* Disable output on SDA, SCL pins. */
589 riic_clear_set_bit(riic, ICCR1_ICE, 0, RIIC_ICCR1);
590
591 pm_runtime_mark_last_busy(dev);
592 pm_runtime_put_sync(dev);
593
594 return reset_control_assert(riic->rstc);
595}
596
597static int riic_i2c_resume(struct device *dev)
598{
599 struct riic_dev *riic = dev_get_drvdata(dev);
600 int ret;
601
602 ret = reset_control_deassert(riic->rstc);
603 if (ret)
604 return ret;
605
606 ret = riic_init_hw(riic);
607 if (ret) {
608 /*
609 * In case this happens there is no way to recover from this
610 * state. The driver will remain loaded. We want to avoid
611 * keeping the reset line de-asserted for no reason.
612 */
613 reset_control_assert(riic->rstc);
614 return ret;
615 }
616
617 i2c_mark_adapter_resumed(&riic->adapter);
618
619 return 0;
620}
621
622static const struct dev_pm_ops riic_i2c_pm_ops = {
623 SYSTEM_SLEEP_PM_OPS(riic_i2c_suspend, riic_i2c_resume)
624};
625
626static const struct of_device_id riic_i2c_dt_ids[] = {
627 { .compatible = "renesas,riic-rz", .data = &riic_rz_a_info },
628 { .compatible = "renesas,riic-r7s72100", .data = &riic_rz_a1h_info, },
629 { .compatible = "renesas,riic-r9a09g057", .data = &riic_rz_v2h_info },
630 { /* Sentinel */ },
631};
632
633static struct platform_driver riic_i2c_driver = {
634 .probe = riic_i2c_probe,
635 .remove = riic_i2c_remove,
636 .driver = {
637 .name = "i2c-riic",
638 .of_match_table = riic_i2c_dt_ids,
639 .pm = pm_ptr(&riic_i2c_pm_ops),
640 },
641};
642
643module_platform_driver(riic_i2c_driver);
644
645MODULE_DESCRIPTION("Renesas RIIC adapter");
646MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
647MODULE_LICENSE("GPL v2");
648MODULE_DEVICE_TABLE(of, riic_i2c_dt_ids);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Renesas RIIC driver
4 *
5 * Copyright (C) 2013 Wolfram Sang <wsa@sang-engineering.com>
6 * Copyright (C) 2013 Renesas Solutions Corp.
7 */
8
9/*
10 * This i2c core has a lot of interrupts, namely 8. We use their chaining as
11 * some kind of state machine.
12 *
13 * 1) The main xfer routine kicks off a transmission by putting the start bit
14 * (or repeated start) on the bus and enabling the transmit interrupt (TIE)
15 * since we need to send the slave address + RW bit in every case.
16 *
17 * 2) TIE sends slave address + RW bit and selects how to continue.
18 *
19 * 3a) Write case: We keep utilizing TIE as long as we have data to send. If we
20 * are done, we switch over to the transmission done interrupt (TEIE) and mark
21 * the message as completed (includes sending STOP) there.
22 *
23 * 3b) Read case: We switch over to receive interrupt (RIE). One dummy read is
24 * needed to start clocking, then we keep receiving until we are done. Note
25 * that we use the RDRFS mode all the time, i.e. we ACK/NACK every byte by
26 * writing to the ACKBT bit. I tried using the RDRFS mode only at the end of a
27 * message to create the final NACK as sketched in the datasheet. This caused
28 * some subtle races (when byte n was processed and byte n+1 was already
29 * waiting), though, and I started with the safe approach.
30 *
31 * 4) If we got a NACK somewhere, we flag the error and stop the transmission
32 * via NAKIE.
33 *
34 * Also check the comments in the interrupt routines for some gory details.
35 */
36
37#include <linux/clk.h>
38#include <linux/completion.h>
39#include <linux/err.h>
40#include <linux/i2c.h>
41#include <linux/interrupt.h>
42#include <linux/io.h>
43#include <linux/module.h>
44#include <linux/of.h>
45#include <linux/platform_device.h>
46#include <linux/pm_runtime.h>
47#include <linux/reset.h>
48
49#define RIIC_ICCR1 0x00
50#define RIIC_ICCR2 0x04
51#define RIIC_ICMR1 0x08
52#define RIIC_ICMR3 0x10
53#define RIIC_ICSER 0x18
54#define RIIC_ICIER 0x1c
55#define RIIC_ICSR2 0x24
56#define RIIC_ICBRL 0x34
57#define RIIC_ICBRH 0x38
58#define RIIC_ICDRT 0x3c
59#define RIIC_ICDRR 0x40
60
61#define ICCR1_ICE 0x80
62#define ICCR1_IICRST 0x40
63#define ICCR1_SOWP 0x10
64
65#define ICCR2_BBSY 0x80
66#define ICCR2_SP 0x08
67#define ICCR2_RS 0x04
68#define ICCR2_ST 0x02
69
70#define ICMR1_CKS_MASK 0x70
71#define ICMR1_BCWP 0x08
72#define ICMR1_CKS(_x) ((((_x) << 4) & ICMR1_CKS_MASK) | ICMR1_BCWP)
73
74#define ICMR3_RDRFS 0x20
75#define ICMR3_ACKWP 0x10
76#define ICMR3_ACKBT 0x08
77
78#define ICIER_TIE 0x80
79#define ICIER_TEIE 0x40
80#define ICIER_RIE 0x20
81#define ICIER_NAKIE 0x10
82#define ICIER_SPIE 0x08
83
84#define ICSR2_NACKF 0x10
85
86#define ICBR_RESERVED 0xe0 /* Should be 1 on writes */
87
88#define RIIC_INIT_MSG -1
89
90struct riic_dev {
91 void __iomem *base;
92 u8 *buf;
93 struct i2c_msg *msg;
94 int bytes_left;
95 int err;
96 int is_last;
97 struct completion msg_done;
98 struct i2c_adapter adapter;
99 struct clk *clk;
100};
101
102struct riic_irq_desc {
103 int res_num;
104 irq_handler_t isr;
105 char *name;
106};
107
108static inline void riic_clear_set_bit(struct riic_dev *riic, u8 clear, u8 set, u8 reg)
109{
110 writeb((readb(riic->base + reg) & ~clear) | set, riic->base + reg);
111}
112
113static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
114{
115 struct riic_dev *riic = i2c_get_adapdata(adap);
116 unsigned long time_left;
117 int i;
118 u8 start_bit;
119
120 pm_runtime_get_sync(adap->dev.parent);
121
122 if (readb(riic->base + RIIC_ICCR2) & ICCR2_BBSY) {
123 riic->err = -EBUSY;
124 goto out;
125 }
126
127 reinit_completion(&riic->msg_done);
128 riic->err = 0;
129
130 writeb(0, riic->base + RIIC_ICSR2);
131
132 for (i = 0, start_bit = ICCR2_ST; i < num; i++) {
133 riic->bytes_left = RIIC_INIT_MSG;
134 riic->buf = msgs[i].buf;
135 riic->msg = &msgs[i];
136 riic->is_last = (i == num - 1);
137
138 writeb(ICIER_NAKIE | ICIER_TIE, riic->base + RIIC_ICIER);
139
140 writeb(start_bit, riic->base + RIIC_ICCR2);
141
142 time_left = wait_for_completion_timeout(&riic->msg_done, riic->adapter.timeout);
143 if (time_left == 0)
144 riic->err = -ETIMEDOUT;
145
146 if (riic->err)
147 break;
148
149 start_bit = ICCR2_RS;
150 }
151
152 out:
153 pm_runtime_put(adap->dev.parent);
154
155 return riic->err ?: num;
156}
157
158static irqreturn_t riic_tdre_isr(int irq, void *data)
159{
160 struct riic_dev *riic = data;
161 u8 val;
162
163 if (!riic->bytes_left)
164 return IRQ_NONE;
165
166 if (riic->bytes_left == RIIC_INIT_MSG) {
167 if (riic->msg->flags & I2C_M_RD)
168 /* On read, switch over to receive interrupt */
169 riic_clear_set_bit(riic, ICIER_TIE, ICIER_RIE, RIIC_ICIER);
170 else
171 /* On write, initialize length */
172 riic->bytes_left = riic->msg->len;
173
174 val = i2c_8bit_addr_from_msg(riic->msg);
175 } else {
176 val = *riic->buf;
177 riic->buf++;
178 riic->bytes_left--;
179 }
180
181 /*
182 * Switch to transmission ended interrupt when done. Do check here
183 * after bytes_left was initialized to support SMBUS_QUICK (new msg has
184 * 0 length then)
185 */
186 if (riic->bytes_left == 0)
187 riic_clear_set_bit(riic, ICIER_TIE, ICIER_TEIE, RIIC_ICIER);
188
189 /*
190 * This acks the TIE interrupt. We get another TIE immediately if our
191 * value could be moved to the shadow shift register right away. So
192 * this must be after updates to ICIER (where we want to disable TIE)!
193 */
194 writeb(val, riic->base + RIIC_ICDRT);
195
196 return IRQ_HANDLED;
197}
198
199static irqreturn_t riic_tend_isr(int irq, void *data)
200{
201 struct riic_dev *riic = data;
202
203 if (readb(riic->base + RIIC_ICSR2) & ICSR2_NACKF) {
204 /* We got a NACKIE */
205 readb(riic->base + RIIC_ICDRR); /* dummy read */
206 riic_clear_set_bit(riic, ICSR2_NACKF, 0, RIIC_ICSR2);
207 riic->err = -ENXIO;
208 } else if (riic->bytes_left) {
209 return IRQ_NONE;
210 }
211
212 if (riic->is_last || riic->err) {
213 riic_clear_set_bit(riic, ICIER_TEIE, ICIER_SPIE, RIIC_ICIER);
214 writeb(ICCR2_SP, riic->base + RIIC_ICCR2);
215 } else {
216 /* Transfer is complete, but do not send STOP */
217 riic_clear_set_bit(riic, ICIER_TEIE, 0, RIIC_ICIER);
218 complete(&riic->msg_done);
219 }
220
221 return IRQ_HANDLED;
222}
223
224static irqreturn_t riic_rdrf_isr(int irq, void *data)
225{
226 struct riic_dev *riic = data;
227
228 if (!riic->bytes_left)
229 return IRQ_NONE;
230
231 if (riic->bytes_left == RIIC_INIT_MSG) {
232 riic->bytes_left = riic->msg->len;
233 readb(riic->base + RIIC_ICDRR); /* dummy read */
234 return IRQ_HANDLED;
235 }
236
237 if (riic->bytes_left == 1) {
238 /* STOP must come before we set ACKBT! */
239 if (riic->is_last) {
240 riic_clear_set_bit(riic, 0, ICIER_SPIE, RIIC_ICIER);
241 writeb(ICCR2_SP, riic->base + RIIC_ICCR2);
242 }
243
244 riic_clear_set_bit(riic, 0, ICMR3_ACKBT, RIIC_ICMR3);
245
246 } else {
247 riic_clear_set_bit(riic, ICMR3_ACKBT, 0, RIIC_ICMR3);
248 }
249
250 /* Reading acks the RIE interrupt */
251 *riic->buf = readb(riic->base + RIIC_ICDRR);
252 riic->buf++;
253 riic->bytes_left--;
254
255 return IRQ_HANDLED;
256}
257
258static irqreturn_t riic_stop_isr(int irq, void *data)
259{
260 struct riic_dev *riic = data;
261
262 /* read back registers to confirm writes have fully propagated */
263 writeb(0, riic->base + RIIC_ICSR2);
264 readb(riic->base + RIIC_ICSR2);
265 writeb(0, riic->base + RIIC_ICIER);
266 readb(riic->base + RIIC_ICIER);
267
268 complete(&riic->msg_done);
269
270 return IRQ_HANDLED;
271}
272
273static u32 riic_func(struct i2c_adapter *adap)
274{
275 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
276}
277
278static const struct i2c_algorithm riic_algo = {
279 .master_xfer = riic_xfer,
280 .functionality = riic_func,
281};
282
283static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
284{
285 int ret = 0;
286 unsigned long rate;
287 int total_ticks, cks, brl, brh;
288
289 pm_runtime_get_sync(riic->adapter.dev.parent);
290
291 if (t->bus_freq_hz > I2C_MAX_FAST_MODE_FREQ) {
292 dev_err(&riic->adapter.dev,
293 "unsupported bus speed (%dHz). %d max\n",
294 t->bus_freq_hz, I2C_MAX_FAST_MODE_FREQ);
295 ret = -EINVAL;
296 goto out;
297 }
298
299 rate = clk_get_rate(riic->clk);
300
301 /*
302 * Assume the default register settings:
303 * FER.SCLE = 1 (SCL sync circuit enabled, adds 2 or 3 cycles)
304 * FER.NFE = 1 (noise circuit enabled)
305 * MR3.NF = 0 (1 cycle of noise filtered out)
306 *
307 * Freq (CKS=000) = (I2CCLK + tr + tf)/ (BRH + 3 + 1) + (BRL + 3 + 1)
308 * Freq (CKS!=000) = (I2CCLK + tr + tf)/ (BRH + 2 + 1) + (BRL + 2 + 1)
309 */
310
311 /*
312 * Determine reference clock rate. We must be able to get the desired
313 * frequency with only 62 clock ticks max (31 high, 31 low).
314 * Aim for a duty of 60% LOW, 40% HIGH.
315 */
316 total_ticks = DIV_ROUND_UP(rate, t->bus_freq_hz ?: 1);
317
318 for (cks = 0; cks < 7; cks++) {
319 /*
320 * 60% low time must be less than BRL + 2 + 1
321 * BRL max register value is 0x1F.
322 */
323 brl = ((total_ticks * 6) / 10);
324 if (brl <= (0x1F + 3))
325 break;
326
327 total_ticks /= 2;
328 rate /= 2;
329 }
330
331 if (brl > (0x1F + 3)) {
332 dev_err(&riic->adapter.dev, "invalid speed (%lu). Too slow.\n",
333 (unsigned long)t->bus_freq_hz);
334 ret = -EINVAL;
335 goto out;
336 }
337
338 brh = total_ticks - brl;
339
340 /* Remove automatic clock ticks for sync circuit and NF */
341 if (cks == 0) {
342 brl -= 4;
343 brh -= 4;
344 } else {
345 brl -= 3;
346 brh -= 3;
347 }
348
349 /*
350 * Remove clock ticks for rise and fall times. Convert ns to clock
351 * ticks.
352 */
353 brl -= t->scl_fall_ns / (1000000000 / rate);
354 brh -= t->scl_rise_ns / (1000000000 / rate);
355
356 /* Adjust for min register values for when SCLE=1 and NFE=1 */
357 if (brl < 1)
358 brl = 1;
359 if (brh < 1)
360 brh = 1;
361
362 pr_debug("i2c-riic: freq=%lu, duty=%d, fall=%lu, rise=%lu, cks=%d, brl=%d, brh=%d\n",
363 rate / total_ticks, ((brl + 3) * 100) / (brl + brh + 6),
364 t->scl_fall_ns / (1000000000 / rate),
365 t->scl_rise_ns / (1000000000 / rate), cks, brl, brh);
366
367 /* Changing the order of accessing IICRST and ICE may break things! */
368 writeb(ICCR1_IICRST | ICCR1_SOWP, riic->base + RIIC_ICCR1);
369 riic_clear_set_bit(riic, 0, ICCR1_ICE, RIIC_ICCR1);
370
371 writeb(ICMR1_CKS(cks), riic->base + RIIC_ICMR1);
372 writeb(brh | ICBR_RESERVED, riic->base + RIIC_ICBRH);
373 writeb(brl | ICBR_RESERVED, riic->base + RIIC_ICBRL);
374
375 writeb(0, riic->base + RIIC_ICSER);
376 writeb(ICMR3_ACKWP | ICMR3_RDRFS, riic->base + RIIC_ICMR3);
377
378 riic_clear_set_bit(riic, ICCR1_IICRST, 0, RIIC_ICCR1);
379
380out:
381 pm_runtime_put(riic->adapter.dev.parent);
382 return ret;
383}
384
385static struct riic_irq_desc riic_irqs[] = {
386 { .res_num = 0, .isr = riic_tend_isr, .name = "riic-tend" },
387 { .res_num = 1, .isr = riic_rdrf_isr, .name = "riic-rdrf" },
388 { .res_num = 2, .isr = riic_tdre_isr, .name = "riic-tdre" },
389 { .res_num = 3, .isr = riic_stop_isr, .name = "riic-stop" },
390 { .res_num = 5, .isr = riic_tend_isr, .name = "riic-nack" },
391};
392
393static void riic_reset_control_assert(void *data)
394{
395 reset_control_assert(data);
396}
397
398static int riic_i2c_probe(struct platform_device *pdev)
399{
400 struct riic_dev *riic;
401 struct i2c_adapter *adap;
402 struct i2c_timings i2c_t;
403 struct reset_control *rstc;
404 int i, ret;
405
406 riic = devm_kzalloc(&pdev->dev, sizeof(*riic), GFP_KERNEL);
407 if (!riic)
408 return -ENOMEM;
409
410 riic->base = devm_platform_ioremap_resource(pdev, 0);
411 if (IS_ERR(riic->base))
412 return PTR_ERR(riic->base);
413
414 riic->clk = devm_clk_get(&pdev->dev, NULL);
415 if (IS_ERR(riic->clk)) {
416 dev_err(&pdev->dev, "missing controller clock");
417 return PTR_ERR(riic->clk);
418 }
419
420 rstc = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
421 if (IS_ERR(rstc))
422 return dev_err_probe(&pdev->dev, PTR_ERR(rstc),
423 "Error: missing reset ctrl\n");
424
425 ret = reset_control_deassert(rstc);
426 if (ret)
427 return ret;
428
429 ret = devm_add_action_or_reset(&pdev->dev, riic_reset_control_assert, rstc);
430 if (ret)
431 return ret;
432
433 for (i = 0; i < ARRAY_SIZE(riic_irqs); i++) {
434 ret = platform_get_irq(pdev, riic_irqs[i].res_num);
435 if (ret < 0)
436 return ret;
437
438 ret = devm_request_irq(&pdev->dev, ret, riic_irqs[i].isr,
439 0, riic_irqs[i].name, riic);
440 if (ret) {
441 dev_err(&pdev->dev, "failed to request irq %s\n", riic_irqs[i].name);
442 return ret;
443 }
444 }
445
446 adap = &riic->adapter;
447 i2c_set_adapdata(adap, riic);
448 strscpy(adap->name, "Renesas RIIC adapter", sizeof(adap->name));
449 adap->owner = THIS_MODULE;
450 adap->algo = &riic_algo;
451 adap->dev.parent = &pdev->dev;
452 adap->dev.of_node = pdev->dev.of_node;
453
454 init_completion(&riic->msg_done);
455
456 i2c_parse_fw_timings(&pdev->dev, &i2c_t, true);
457
458 pm_runtime_enable(&pdev->dev);
459
460 ret = riic_init_hw(riic, &i2c_t);
461 if (ret)
462 goto out;
463
464 ret = i2c_add_adapter(adap);
465 if (ret)
466 goto out;
467
468 platform_set_drvdata(pdev, riic);
469
470 dev_info(&pdev->dev, "registered with %dHz bus speed\n",
471 i2c_t.bus_freq_hz);
472 return 0;
473
474out:
475 pm_runtime_disable(&pdev->dev);
476 return ret;
477}
478
479static void riic_i2c_remove(struct platform_device *pdev)
480{
481 struct riic_dev *riic = platform_get_drvdata(pdev);
482
483 pm_runtime_get_sync(&pdev->dev);
484 writeb(0, riic->base + RIIC_ICIER);
485 pm_runtime_put(&pdev->dev);
486 i2c_del_adapter(&riic->adapter);
487 pm_runtime_disable(&pdev->dev);
488}
489
490static const struct of_device_id riic_i2c_dt_ids[] = {
491 { .compatible = "renesas,riic-rz", },
492 { /* Sentinel */ },
493};
494
495static struct platform_driver riic_i2c_driver = {
496 .probe = riic_i2c_probe,
497 .remove_new = riic_i2c_remove,
498 .driver = {
499 .name = "i2c-riic",
500 .of_match_table = riic_i2c_dt_ids,
501 },
502};
503
504module_platform_driver(riic_i2c_driver);
505
506MODULE_DESCRIPTION("Renesas RIIC adapter");
507MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
508MODULE_LICENSE("GPL v2");
509MODULE_DEVICE_TABLE(of, riic_i2c_dt_ids);