1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * RTC driver for the Armada 38x Marvell SoCs
4 *
5 * Copyright (C) 2015 Marvell
6 *
7 * Gregory Clement <gregory.clement@free-electrons.com>
8 */
9
10#include <linux/delay.h>
11#include <linux/io.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/platform_device.h>
15#include <linux/rtc.h>
16
17#define RTC_STATUS 0x0
18#define RTC_STATUS_ALARM1 BIT(0)
19#define RTC_STATUS_ALARM2 BIT(1)
20#define RTC_IRQ1_CONF 0x4
21#define RTC_IRQ2_CONF 0x8
22#define RTC_IRQ_AL_EN BIT(0)
23#define RTC_IRQ_FREQ_EN BIT(1)
24#define RTC_IRQ_FREQ_1HZ BIT(2)
25#define RTC_CCR 0x18
26#define RTC_CCR_MODE BIT(15)
27#define RTC_CONF_TEST 0x1C
28#define RTC_NOMINAL_TIMING BIT(13)
29
30#define RTC_TIME 0xC
31#define RTC_ALARM1 0x10
32#define RTC_ALARM2 0x14
33
34/* Armada38x SoC registers */
35#define RTC_38X_BRIDGE_TIMING_CTL 0x0
36#define RTC_38X_PERIOD_OFFS 0
37#define RTC_38X_PERIOD_MASK (0x3FF << RTC_38X_PERIOD_OFFS)
38#define RTC_38X_READ_DELAY_OFFS 26
39#define RTC_38X_READ_DELAY_MASK (0x1F << RTC_38X_READ_DELAY_OFFS)
40
41/* Armada 7K/8K registers */
42#define RTC_8K_BRIDGE_TIMING_CTL0 0x0
43#define RTC_8K_WRCLK_PERIOD_OFFS 0
44#define RTC_8K_WRCLK_PERIOD_MASK (0xFFFF << RTC_8K_WRCLK_PERIOD_OFFS)
45#define RTC_8K_WRCLK_SETUP_OFFS 16
46#define RTC_8K_WRCLK_SETUP_MASK (0xFFFF << RTC_8K_WRCLK_SETUP_OFFS)
47#define RTC_8K_BRIDGE_TIMING_CTL1 0x4
48#define RTC_8K_READ_DELAY_OFFS 0
49#define RTC_8K_READ_DELAY_MASK (0xFFFF << RTC_8K_READ_DELAY_OFFS)
50
51#define RTC_8K_ISR 0x10
52#define RTC_8K_IMR 0x14
53#define RTC_8K_ALARM2 BIT(0)
54
55#define SOC_RTC_INTERRUPT 0x8
56#define SOC_RTC_ALARM1 BIT(0)
57#define SOC_RTC_ALARM2 BIT(1)
58#define SOC_RTC_ALARM1_MASK BIT(2)
59#define SOC_RTC_ALARM2_MASK BIT(3)
60
61#define SAMPLE_NR 100
62
63struct value_to_freq {
64 u32 value;
65 u8 freq;
66};
67
68struct armada38x_rtc {
69 struct rtc_device *rtc_dev;
70 void __iomem *regs;
71 void __iomem *regs_soc;
72 spinlock_t lock;
73 int irq;
74 bool initialized;
75 struct value_to_freq *val_to_freq;
76 const struct armada38x_rtc_data *data;
77};
78
79#define ALARM1 0
80#define ALARM2 1
81
82#define ALARM_REG(base, alarm) ((base) + (alarm) * sizeof(u32))
83
84struct armada38x_rtc_data {
85 /* Initialize the RTC-MBUS bridge timing */
86 void (*update_mbus_timing)(struct armada38x_rtc *rtc);
87 u32 (*read_rtc_reg)(struct armada38x_rtc *rtc, u8 rtc_reg);
88 void (*clear_isr)(struct armada38x_rtc *rtc);
89 void (*unmask_interrupt)(struct armada38x_rtc *rtc);
90 u32 alarm;
91};
92
93/*
94 * According to the datasheet, the OS should wait 5us after every
95 * register write to the RTC hard macro so that the required update
96 * can occur without holding off the system bus
97 * According to errata RES-3124064, Write to any RTC register
98 * may fail. As a workaround, before writing to RTC
99 * register, issue a dummy write of 0x0 twice to RTC Status
100 * register.
101 */
102
103static void rtc_delayed_write(u32 val, struct armada38x_rtc *rtc, int offset)
104{
105 writel(val: 0, addr: rtc->regs + RTC_STATUS);
106 writel(val: 0, addr: rtc->regs + RTC_STATUS);
107 writel(val, addr: rtc->regs + offset);
108 udelay(usec: 5);
109}
110
111/* Update RTC-MBUS bridge timing parameters */
112static void rtc_update_38x_mbus_timing_params(struct armada38x_rtc *rtc)
113{
114 u32 reg;
115
116 reg = readl(addr: rtc->regs_soc + RTC_38X_BRIDGE_TIMING_CTL);
117 reg &= ~RTC_38X_PERIOD_MASK;
118 reg |= 0x3FF << RTC_38X_PERIOD_OFFS; /* Maximum value */
119 reg &= ~RTC_38X_READ_DELAY_MASK;
120 reg |= 0x1F << RTC_38X_READ_DELAY_OFFS; /* Maximum value */
121 writel(val: reg, addr: rtc->regs_soc + RTC_38X_BRIDGE_TIMING_CTL);
122}
123
124static void rtc_update_8k_mbus_timing_params(struct armada38x_rtc *rtc)
125{
126 u32 reg;
127
128 reg = readl(addr: rtc->regs_soc + RTC_8K_BRIDGE_TIMING_CTL0);
129 reg &= ~RTC_8K_WRCLK_PERIOD_MASK;
130 reg |= 0x3FF << RTC_8K_WRCLK_PERIOD_OFFS;
131 reg &= ~RTC_8K_WRCLK_SETUP_MASK;
132 reg |= 0x29 << RTC_8K_WRCLK_SETUP_OFFS;
133 writel(val: reg, addr: rtc->regs_soc + RTC_8K_BRIDGE_TIMING_CTL0);
134
135 reg = readl(addr: rtc->regs_soc + RTC_8K_BRIDGE_TIMING_CTL1);
136 reg &= ~RTC_8K_READ_DELAY_MASK;
137 reg |= 0x3F << RTC_8K_READ_DELAY_OFFS;
138 writel(val: reg, addr: rtc->regs_soc + RTC_8K_BRIDGE_TIMING_CTL1);
139}
140
141static u32 read_rtc_register(struct armada38x_rtc *rtc, u8 rtc_reg)
142{
143 return readl(addr: rtc->regs + rtc_reg);
144}
145
146static u32 read_rtc_register_38x_wa(struct armada38x_rtc *rtc, u8 rtc_reg)
147{
148 int i, index_max = 0, max = 0;
149
150 for (i = 0; i < SAMPLE_NR; i++) {
151 rtc->val_to_freq[i].value = readl(addr: rtc->regs + rtc_reg);
152 rtc->val_to_freq[i].freq = 0;
153 }
154
155 for (i = 0; i < SAMPLE_NR; i++) {
156 int j = 0;
157 u32 value = rtc->val_to_freq[i].value;
158
159 while (rtc->val_to_freq[j].freq) {
160 if (rtc->val_to_freq[j].value == value) {
161 rtc->val_to_freq[j].freq++;
162 break;
163 }
164 j++;
165 }
166
167 if (!rtc->val_to_freq[j].freq) {
168 rtc->val_to_freq[j].value = value;
169 rtc->val_to_freq[j].freq = 1;
170 }
171
172 if (rtc->val_to_freq[j].freq > max) {
173 index_max = j;
174 max = rtc->val_to_freq[j].freq;
175 }
176
177 /*
178 * If a value already has half of the sample this is the most
179 * frequent one and we can stop the research right now
180 */
181 if (max > SAMPLE_NR / 2)
182 break;
183 }
184
185 return rtc->val_to_freq[index_max].value;
186}
187
188static void armada38x_clear_isr(struct armada38x_rtc *rtc)
189{
190 u32 val = readl(addr: rtc->regs_soc + SOC_RTC_INTERRUPT);
191
192 writel(val: val & ~SOC_RTC_ALARM1, addr: rtc->regs_soc + SOC_RTC_INTERRUPT);
193}
194
195static void armada38x_unmask_interrupt(struct armada38x_rtc *rtc)
196{
197 u32 val = readl(addr: rtc->regs_soc + SOC_RTC_INTERRUPT);
198
199 writel(val: val | SOC_RTC_ALARM1_MASK, addr: rtc->regs_soc + SOC_RTC_INTERRUPT);
200}
201
202static void armada8k_clear_isr(struct armada38x_rtc *rtc)
203{
204 writel(RTC_8K_ALARM2, addr: rtc->regs_soc + RTC_8K_ISR);
205}
206
207static void armada8k_unmask_interrupt(struct armada38x_rtc *rtc)
208{
209 writel(RTC_8K_ALARM2, addr: rtc->regs_soc + RTC_8K_IMR);
210}
211
212static int armada38x_rtc_read_time(struct device *dev, struct rtc_time *tm)
213{
214 struct armada38x_rtc *rtc = dev_get_drvdata(dev);
215 unsigned long time, flags;
216
217 spin_lock_irqsave(&rtc->lock, flags);
218 time = rtc->data->read_rtc_reg(rtc, RTC_TIME);
219 spin_unlock_irqrestore(lock: &rtc->lock, flags);
220
221 rtc_time64_to_tm(time, tm);
222
223 return 0;
224}
225
226static void armada38x_rtc_reset(struct armada38x_rtc *rtc)
227{
228 u32 reg;
229
230 reg = rtc->data->read_rtc_reg(rtc, RTC_CONF_TEST);
231 /* If bits [7:0] are non-zero, assume RTC was uninitialized */
232 if (reg & 0xff) {
233 rtc_delayed_write(val: 0, rtc, RTC_CONF_TEST);
234 msleep(msecs: 500); /* Oscillator startup time */
235 rtc_delayed_write(val: 0, rtc, RTC_TIME);
236 rtc_delayed_write(SOC_RTC_ALARM1 | SOC_RTC_ALARM2, rtc,
237 RTC_STATUS);
238 rtc_delayed_write(RTC_NOMINAL_TIMING, rtc, RTC_CCR);
239 }
240 rtc->initialized = true;
241}
242
243static int armada38x_rtc_set_time(struct device *dev, struct rtc_time *tm)
244{
245 struct armada38x_rtc *rtc = dev_get_drvdata(dev);
246 unsigned long time, flags;
247
248 time = rtc_tm_to_time64(tm);
249
250 if (!rtc->initialized)
251 armada38x_rtc_reset(rtc);
252
253 spin_lock_irqsave(&rtc->lock, flags);
254 rtc_delayed_write(val: time, rtc, RTC_TIME);
255 spin_unlock_irqrestore(lock: &rtc->lock, flags);
256
257 return 0;
258}
259
260static int armada38x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
261{
262 struct armada38x_rtc *rtc = dev_get_drvdata(dev);
263 unsigned long time, flags;
264 u32 reg = ALARM_REG(RTC_ALARM1, rtc->data->alarm);
265 u32 reg_irq = ALARM_REG(RTC_IRQ1_CONF, rtc->data->alarm);
266 u32 val;
267
268 spin_lock_irqsave(&rtc->lock, flags);
269
270 time = rtc->data->read_rtc_reg(rtc, reg);
271 val = rtc->data->read_rtc_reg(rtc, reg_irq) & RTC_IRQ_AL_EN;
272
273 spin_unlock_irqrestore(lock: &rtc->lock, flags);
274
275 alrm->enabled = val ? 1 : 0;
276 rtc_time64_to_tm(time, tm: &alrm->time);
277
278 return 0;
279}
280
281static int armada38x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
282{
283 struct armada38x_rtc *rtc = dev_get_drvdata(dev);
284 u32 reg = ALARM_REG(RTC_ALARM1, rtc->data->alarm);
285 u32 reg_irq = ALARM_REG(RTC_IRQ1_CONF, rtc->data->alarm);
286 unsigned long time, flags;
287
288 time = rtc_tm_to_time64(tm: &alrm->time);
289
290 spin_lock_irqsave(&rtc->lock, flags);
291
292 rtc_delayed_write(val: time, rtc, offset: reg);
293
294 if (alrm->enabled) {
295 rtc_delayed_write(RTC_IRQ_AL_EN, rtc, offset: reg_irq);
296 rtc->data->unmask_interrupt(rtc);
297 }
298
299 spin_unlock_irqrestore(lock: &rtc->lock, flags);
300
301 return 0;
302}
303
304static int armada38x_rtc_alarm_irq_enable(struct device *dev,
305 unsigned int enabled)
306{
307 struct armada38x_rtc *rtc = dev_get_drvdata(dev);
308 u32 reg_irq = ALARM_REG(RTC_IRQ1_CONF, rtc->data->alarm);
309 unsigned long flags;
310
311 spin_lock_irqsave(&rtc->lock, flags);
312
313 if (enabled)
314 rtc_delayed_write(RTC_IRQ_AL_EN, rtc, offset: reg_irq);
315 else
316 rtc_delayed_write(val: 0, rtc, offset: reg_irq);
317
318 spin_unlock_irqrestore(lock: &rtc->lock, flags);
319
320 return 0;
321}
322
323static irqreturn_t armada38x_rtc_alarm_irq(int irq, void *data)
324{
325 struct armada38x_rtc *rtc = data;
326 u32 val;
327 int event = RTC_IRQF | RTC_AF;
328 u32 reg_irq = ALARM_REG(RTC_IRQ1_CONF, rtc->data->alarm);
329
330 dev_dbg(&rtc->rtc_dev->dev, "%s:irq(%d)\n", __func__, irq);
331
332 spin_lock(lock: &rtc->lock);
333
334 rtc->data->clear_isr(rtc);
335 val = rtc->data->read_rtc_reg(rtc, reg_irq);
336 /* disable all the interrupts for alarm*/
337 rtc_delayed_write(val: 0, rtc, offset: reg_irq);
338 /* Ack the event */
339 rtc_delayed_write(val: 1 << rtc->data->alarm, rtc, RTC_STATUS);
340
341 spin_unlock(lock: &rtc->lock);
342
343 if (val & RTC_IRQ_FREQ_EN) {
344 if (val & RTC_IRQ_FREQ_1HZ)
345 event |= RTC_UF;
346 else
347 event |= RTC_PF;
348 }
349
350 rtc_update_irq(rtc: rtc->rtc_dev, num: 1, events: event);
351
352 return IRQ_HANDLED;
353}
354
355/*
356 * The information given in the Armada 388 functional spec is complex.
357 * They give two different formulas for calculating the offset value,
358 * but when considering "Offset" as an 8-bit signed integer, they both
359 * reduce down to (we shall rename "Offset" as "val" here):
360 *
361 * val = (f_ideal / f_measured - 1) / resolution where f_ideal = 32768
362 *
363 * Converting to time, f = 1/t:
364 * val = (t_measured / t_ideal - 1) / resolution where t_ideal = 1/32768
365 *
366 * => t_measured / t_ideal = val * resolution + 1
367 *
368 * "offset" in the RTC interface is defined as:
369 * t = t0 * (1 + offset * 1e-9)
370 * where t is the desired period, t0 is the measured period with a zero
371 * offset, which is t_measured above. With t0 = t_measured and t = t_ideal,
372 * offset = (t_ideal / t_measured - 1) / 1e-9
373 *
374 * => t_ideal / t_measured = offset * 1e-9 + 1
375 *
376 * so:
377 *
378 * offset * 1e-9 + 1 = 1 / (val * resolution + 1)
379 *
380 * We want "resolution" to be an integer, so resolution = R * 1e-9, giving
381 * offset = 1e18 / (val * R + 1e9) - 1e9
382 * val = (1e18 / (offset + 1e9) - 1e9) / R
383 * with a common transformation:
384 * f(x) = 1e18 / (x + 1e9) - 1e9
385 * offset = f(val * R)
386 * val = f(offset) / R
387 *
388 * Armada 38x supports two modes, fine mode (954ppb) and coarse mode (3815ppb).
389 */
390static long armada38x_ppb_convert(long ppb)
391{
392 long div = ppb + 1000000000L;
393
394 return div_s64(dividend: 1000000000000000000LL + div / 2, divisor: div) - 1000000000L;
395}
396
397static int armada38x_rtc_read_offset(struct device *dev, long *offset)
398{
399 struct armada38x_rtc *rtc = dev_get_drvdata(dev);
400 unsigned long ccr, flags;
401 long ppb_cor;
402
403 spin_lock_irqsave(&rtc->lock, flags);
404 ccr = rtc->data->read_rtc_reg(rtc, RTC_CCR);
405 spin_unlock_irqrestore(lock: &rtc->lock, flags);
406
407 ppb_cor = (ccr & RTC_CCR_MODE ? 3815 : 954) * (s8)ccr;
408 /* ppb_cor + 1000000000L can never be zero */
409 *offset = armada38x_ppb_convert(ppb: ppb_cor);
410
411 return 0;
412}
413
414static int armada38x_rtc_set_offset(struct device *dev, long offset)
415{
416 struct armada38x_rtc *rtc = dev_get_drvdata(dev);
417 unsigned long ccr = 0;
418 long ppb_cor, off;
419
420 /*
421 * The maximum ppb_cor is -128 * 3815 .. 127 * 3815, but we
422 * need to clamp the input. This equates to -484270 .. 488558.
423 * Not only is this to stop out of range "off" but also to
424 * avoid the division by zero in armada38x_ppb_convert().
425 */
426 offset = clamp(offset, -484270L, 488558L);
427
428 ppb_cor = armada38x_ppb_convert(ppb: offset);
429
430 /*
431 * Use low update mode where possible, which gives a better
432 * resolution of correction.
433 */
434 off = DIV_ROUND_CLOSEST(ppb_cor, 954);
435 if (off > 127 || off < -128) {
436 ccr = RTC_CCR_MODE;
437 off = DIV_ROUND_CLOSEST(ppb_cor, 3815);
438 }
439
440 /*
441 * Armada 388 requires a bit pattern in bits 14..8 depending on
442 * the sign bit: { 0, ~S, S, S, S, S, S }
443 */
444 ccr |= (off & 0x3fff) ^ 0x2000;
445 rtc_delayed_write(val: ccr, rtc, RTC_CCR);
446
447 return 0;
448}
449
450static const struct rtc_class_ops armada38x_rtc_ops = {
451 .read_time = armada38x_rtc_read_time,
452 .set_time = armada38x_rtc_set_time,
453 .read_alarm = armada38x_rtc_read_alarm,
454 .set_alarm = armada38x_rtc_set_alarm,
455 .alarm_irq_enable = armada38x_rtc_alarm_irq_enable,
456 .read_offset = armada38x_rtc_read_offset,
457 .set_offset = armada38x_rtc_set_offset,
458};
459
460static const struct armada38x_rtc_data armada38x_data = {
461 .update_mbus_timing = rtc_update_38x_mbus_timing_params,
462 .read_rtc_reg = read_rtc_register_38x_wa,
463 .clear_isr = armada38x_clear_isr,
464 .unmask_interrupt = armada38x_unmask_interrupt,
465 .alarm = ALARM1,
466};
467
468static const struct armada38x_rtc_data armada8k_data = {
469 .update_mbus_timing = rtc_update_8k_mbus_timing_params,
470 .read_rtc_reg = read_rtc_register,
471 .clear_isr = armada8k_clear_isr,
472 .unmask_interrupt = armada8k_unmask_interrupt,
473 .alarm = ALARM2,
474};
475
476static const struct of_device_id armada38x_rtc_of_match_table[] = {
477 {
478 .compatible = "marvell,armada-380-rtc",
479 .data = &armada38x_data,
480 },
481 {
482 .compatible = "marvell,armada-8k-rtc",
483 .data = &armada8k_data,
484 },
485 {}
486};
487MODULE_DEVICE_TABLE(of, armada38x_rtc_of_match_table);
488
489static __init int armada38x_rtc_probe(struct platform_device *pdev)
490{
491 struct armada38x_rtc *rtc;
492
493 rtc = devm_kzalloc(dev: &pdev->dev, size: sizeof(struct armada38x_rtc),
494 GFP_KERNEL);
495 if (!rtc)
496 return -ENOMEM;
497
498 rtc->data = of_device_get_match_data(dev: &pdev->dev);
499
500 rtc->val_to_freq = devm_kcalloc(dev: &pdev->dev, SAMPLE_NR,
501 size: sizeof(struct value_to_freq), GFP_KERNEL);
502 if (!rtc->val_to_freq)
503 return -ENOMEM;
504
505 spin_lock_init(&rtc->lock);
506
507 rtc->regs = devm_platform_ioremap_resource_byname(pdev, name: "rtc");
508 if (IS_ERR(ptr: rtc->regs))
509 return PTR_ERR(ptr: rtc->regs);
510 rtc->regs_soc = devm_platform_ioremap_resource_byname(pdev, name: "rtc-soc");
511 if (IS_ERR(ptr: rtc->regs_soc))
512 return PTR_ERR(ptr: rtc->regs_soc);
513
514 rtc->irq = platform_get_irq(pdev, 0);
515 if (rtc->irq < 0)
516 return rtc->irq;
517
518 rtc->rtc_dev = devm_rtc_allocate_device(dev: &pdev->dev);
519 if (IS_ERR(ptr: rtc->rtc_dev))
520 return PTR_ERR(ptr: rtc->rtc_dev);
521
522 if (devm_request_irq(dev: &pdev->dev, irq: rtc->irq, handler: armada38x_rtc_alarm_irq,
523 irqflags: 0, devname: pdev->name, dev_id: rtc) < 0) {
524 dev_warn(&pdev->dev, "Interrupt not available.\n");
525 rtc->irq = -1;
526 }
527 platform_set_drvdata(pdev, data: rtc);
528
529 if (rtc->irq != -1)
530 device_init_wakeup(dev: &pdev->dev, enable: true);
531 else
532 clear_bit(RTC_FEATURE_ALARM, addr: rtc->rtc_dev->features);
533
534 /* Update RTC-MBUS bridge timing parameters */
535 rtc->data->update_mbus_timing(rtc);
536
537 rtc->rtc_dev->ops = &armada38x_rtc_ops;
538 rtc->rtc_dev->range_max = U32_MAX;
539
540 return devm_rtc_register_device(rtc->rtc_dev);
541}
542
543#ifdef CONFIG_PM_SLEEP
544static int armada38x_rtc_suspend(struct device *dev)
545{
546 if (device_may_wakeup(dev)) {
547 struct armada38x_rtc *rtc = dev_get_drvdata(dev);
548
549 return enable_irq_wake(irq: rtc->irq);
550 }
551
552 return 0;
553}
554
555static int armada38x_rtc_resume(struct device *dev)
556{
557 if (device_may_wakeup(dev)) {
558 struct armada38x_rtc *rtc = dev_get_drvdata(dev);
559
560 /* Update RTC-MBUS bridge timing parameters */
561 rtc->data->update_mbus_timing(rtc);
562
563 return disable_irq_wake(irq: rtc->irq);
564 }
565
566 return 0;
567}
568#endif
569
570static SIMPLE_DEV_PM_OPS(armada38x_rtc_pm_ops,
571 armada38x_rtc_suspend, armada38x_rtc_resume);
572
573static struct platform_driver armada38x_rtc_driver = {
574 .driver = {
575 .name = "armada38x-rtc",
576 .pm = &armada38x_rtc_pm_ops,
577 .of_match_table = armada38x_rtc_of_match_table,
578 },
579};
580
581module_platform_driver_probe(armada38x_rtc_driver, armada38x_rtc_probe);
582
583MODULE_DESCRIPTION("Marvell Armada 38x RTC driver");
584MODULE_AUTHOR("Gregory CLEMENT <gregory.clement@free-electrons.com>");
585MODULE_LICENSE("GPL");
586

source code of linux/drivers/rtc/rtc-armada38x.c