aboutsummaryrefslogtreecommitdiff
path: root/drivers/rtc/rtc-snvs.c
blob: bd929b0e7d7defdd94335cca248a8526ee24d1e0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
// SPDX-License-Identifier: GPL-2.0+
//
// Copyright (C) 2011-2012 Freescale Semiconductor, Inc.

#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_wakeirq.h>
#include <linux/rtc.h>
#include <linux/clk.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>

#define SNVS_LPREGISTER_OFFSET	0x34

/* These register offsets are relative to LP (Low Power) range */
#define SNVS_LPCR		0x04
#define SNVS_LPSR		0x18
#define SNVS_LPSRTCMR		0x1c
#define SNVS_LPSRTCLR		0x20
#define SNVS_LPTAR		0x24
#define SNVS_LPPGDR		0x30

#define SNVS_LPCR_SRTC_ENV	(1 << 0)
#define SNVS_LPCR_LPTA_EN	(1 << 1)
#define SNVS_LPCR_LPWUI_EN	(1 << 3)
#define SNVS_LPSR_LPTA		(1 << 0)

#define SNVS_LPPGDR_INIT	0x41736166
#define CNTR_TO_SECS_SH		15

struct snvs_rtc_data {
	struct rtc_device *rtc;
	struct regmap *regmap;
	int offset;
	int irq;
	struct clk *clk;
};

/* Read 64 bit timer register, which could be in inconsistent state */
static u64 rtc_read_lpsrt(struct snvs_rtc_data *data)
{
	u32 msb, lsb;

	regmap_read(data->regmap, data->offset + SNVS_LPSRTCMR, &msb);
	regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &lsb);
	return (u64)msb << 32 | lsb;
}

/* Read the secure real time counter, taking care to deal with the cases of the
 * counter updating while being read.
 */
static u32 rtc_read_lp_counter(struct snvs_rtc_data *data)
{
	u64 read1, read2;
	unsigned int timeout = 100;

	/* As expected, the registers might update between the read of the LSB
	 * reg and the MSB reg.  It's also possible that one register might be
	 * in partially modified state as well.
	 */
	read1 = rtc_read_lpsrt(data);
	do {
		read2 = read1;
		read1 = rtc_read_lpsrt(data);
	} while (read1 != read2 && --timeout);
	if (!timeout)
		dev_err(&data->rtc->dev, "Timeout trying to get valid LPSRT Counter read\n");

	/* Convert 47-bit counter to 32-bit raw second count */
	return (u32) (read1 >> CNTR_TO_SECS_SH);
}

/* Just read the lsb from the counter, dealing with inconsistent state */
static int rtc_read_lp_counter_lsb(struct snvs_rtc_data *data, u32 *lsb)
{
	u32 count1, count2;
	unsigned int timeout = 100;

	regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count1);
	do {
		count2 = count1;
		regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count1);
	} while (count1 != count2 && --timeout);
	if (!timeout) {
		dev_err(&data->rtc->dev, "Timeout trying to get valid LPSRT Counter read\n");
		return -ETIMEDOUT;
	}

	*lsb = count1;
	return 0;
}

static int rtc_write_sync_lp(struct snvs_rtc_data *data)
{
	u32 count1, count2;
	u32 elapsed;
	unsigned int timeout = 1000;
	int ret;

	ret = rtc_read_lp_counter_lsb(data, &count1);
	if (ret)
		return ret;

	/* Wait for 3 CKIL cycles, about 61.0-91.5 µs */
	do {
		ret = rtc_read_lp_counter_lsb(data, &count2);
		if (ret)
			return ret;
		elapsed = count2 - count1; /* wrap around _is_ handled! */
	} while (elapsed < 3 && --timeout);
	if (!timeout) {
		dev_err(&data->rtc->dev, "Timeout waiting for LPSRT Counter to change\n");
		return -ETIMEDOUT;
	}
	return 0;
}

static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable)
{
	int timeout = 1000;
	u32 lpcr;

	regmap_update_bits(data->regmap, data->offset + SNVS_LPCR, SNVS_LPCR_SRTC_ENV,
			   enable ? SNVS_LPCR_SRTC_ENV : 0);

	while (--timeout) {
		regmap_read(data->regmap, data->offset + SNVS_LPCR, &lpcr);

		if (enable) {
			if (lpcr & SNVS_LPCR_SRTC_ENV)
				break;
		} else {
			if (!(lpcr & SNVS_LPCR_SRTC_ENV))
				break;
		}
	}

	if (!timeout)
		return -ETIMEDOUT;

	return 0;
}

static int snvs_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct snvs_rtc_data *data = dev_get_drvdata(dev);
	unsigned long time;
	int ret;

	ret = clk_enable(data->clk);
	if (ret)
		return ret;

	time = rtc_read_lp_counter(data);
	rtc_time64_to_tm(time, tm);

	clk_disable(data->clk);

	return 0;
}

static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct snvs_rtc_data *data = dev_get_drvdata(dev);
	unsigned long time = rtc_tm_to_time64(tm);
	int ret;

	ret = clk_enable(data->clk);
	if (ret)
		return ret;

	/* Disable RTC first */
	ret = snvs_rtc_enable(data, false);
	if (ret)
		return ret;

	/* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */
	regmap_write(data->regmap, data->offset + SNVS_LPSRTCLR, time << CNTR_TO_SECS_SH);
	regmap_write(data->regmap, data->offset + SNVS_LPSRTCMR, time >> (32 - CNTR_TO_SECS_SH));

	/* Enable RTC again */
	ret = snvs_rtc_enable(data, true);

	clk_disable(data->clk);

	return ret;
}

static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct snvs_rtc_data *data = dev_get_drvdata(dev);
	u32 lptar, lpsr;
	int ret;

	ret = clk_enable(data->clk);
	if (ret)
		return ret;

	regmap_read(data->regmap, data->offset + SNVS_LPTAR, &lptar);
	rtc_time64_to_tm(lptar, &alrm->time);

	regmap_read(data->regmap, data->offset + SNVS_LPSR, &lpsr);
	alrm->pending = (lpsr & SNVS_LPSR_LPTA) ? 1 : 0;

	clk_disable(data->clk);

	return 0;
}

static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
{
	struct snvs_rtc_data *data = dev_get_drvdata(dev);
	int ret;

	ret = clk_enable(data->clk);
	if (ret)
		return ret;

	regmap_update_bits(data->regmap, data->offset + SNVS_LPCR,
			   (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN),
			   enable ? (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN) : 0);

	ret = rtc_write_sync_lp(data);

	clk_disable(data->clk);

	return ret;
}

static int snvs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct snvs_rtc_data *data = dev_get_drvdata(dev);
	unsigned long time = rtc_tm_to_time64(&alrm->time);
	int ret;

	ret = clk_enable(data->clk);
	if (ret)
		return ret;

	regmap_update_bits(data->regmap, data->offset + SNVS_LPCR, SNVS_LPCR_LPTA_EN, 0);
	ret = rtc_write_sync_lp(data);
	if (ret)
		return ret;
	regmap_write(data->regmap, data->offset + SNVS_LPTAR, time);

	/* Clear alarm interrupt status bit */
	regmap_write(data->regmap, data->offset + SNVS_LPSR, SNVS_LPSR_LPTA);

	clk_disable(data->clk);

	return snvs_rtc_alarm_irq_enable(dev, alrm->enabled);
}

static const struct rtc_class_ops snvs_rtc_ops = {
	.read_time = snvs_rtc_read_time,
	.set_time = snvs_rtc_set_time,
	.read_alarm = snvs_rtc_read_alarm,
	.set_alarm = snvs_rtc_set_alarm,
	.alarm_irq_enable = snvs_rtc_alarm_irq_enable,
};

static irqreturn_t snvs_rtc_irq_handler(int irq, void *dev_id)
{
	struct device *dev = dev_id;
	struct snvs_rtc_data *data = dev_get_drvdata(dev);
	u32 lpsr;
	u32 events = 0;

	clk_enable(data->clk);

	regmap_read(data->regmap, data->offset + SNVS_LPSR, &lpsr);

	if (lpsr & SNVS_LPSR_LPTA) {
		events |= (RTC_AF | RTC_IRQF);

		/* RTC alarm should be one-shot */
		snvs_rtc_alarm_irq_enable(dev, 0);

		rtc_update_irq(data->rtc, 1, events);
	}

	/* clear interrupt status */
	regmap_write(data->regmap, data->offset + SNVS_LPSR, lpsr);

	clk_disable(data->clk);

	return events ? IRQ_HANDLED : IRQ_NONE;
}

static const struct regmap_config snvs_rtc_config = {
	.reg_bits = 32,
	.val_bits = 32,
	.reg_stride = 4,
};

static void snvs_rtc_action(void *data)
{
	clk_disable_unprepare(data);
}

static int snvs_rtc_probe(struct platform_device *pdev)
{
	struct snvs_rtc_data *data;
	int ret;
	void __iomem *mmio;

	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->rtc = devm_rtc_allocate_device(&pdev->dev);
	if (IS_ERR(data->rtc))
		return PTR_ERR(data->rtc);

	data->regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");

	if (IS_ERR(data->regmap)) {
		dev_warn(&pdev->dev, "snvs rtc: you use old dts file, please update it\n");

		mmio = devm_platform_ioremap_resource(pdev, 0);
		if (IS_ERR(mmio))
			return PTR_ERR(mmio);

		data->regmap = devm_regmap_init_mmio(&pdev->dev, mmio, &snvs_rtc_config);
	} else {
		data->offset = SNVS_LPREGISTER_OFFSET;
		of_property_read_u32(pdev->dev.of_node, "offset", &data->offset);
	}

	if (IS_ERR(data->regmap)) {
		dev_err(&pdev->dev, "Can't find snvs syscon\n");
		return -ENODEV;
	}

	data->irq = platform_get_irq(pdev, 0);
	if (data->irq < 0)
		return data->irq;

	data->clk = devm_clk_get(&pdev->dev, "snvs-rtc");
	if (IS_ERR(data->clk)) {
		data->clk = NULL;
	} else {
		ret = clk_prepare_enable(data->clk);
		if (ret) {
			dev_err(&pdev->dev,
				"Could not prepare or enable the snvs clock\n");
			return ret;
		}
	}

	ret = devm_add_action_or_reset(&pdev->dev, snvs_rtc_action, data->clk);
	if (ret)
		return ret;

	platform_set_drvdata(pdev, data);

	/* Initialize glitch detect */
	regmap_write(data->regmap, data->offset + SNVS_LPPGDR, SNVS_LPPGDR_INIT);

	/* Clear interrupt status */
	regmap_write(data->regmap, data->offset + SNVS_LPSR, 0xffffffff);

	/* Enable RTC */
	ret = snvs_rtc_enable(data, true);
	if (ret) {
		dev_err(&pdev->dev, "failed to enable rtc %d\n", ret);
		return ret;
	}

	device_init_wakeup(&pdev->dev, true);
	ret = dev_pm_set_wake_irq(&pdev->dev, data->irq);
	if (ret)
		dev_err(&pdev->dev, "failed to enable irq wake\n");

	ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler,
			       IRQF_SHARED, "rtc alarm", &pdev->dev);
	if (ret) {
		dev_err(&pdev->dev, "failed to request irq %d: %d\n",
			data->irq, ret);
		return ret;
	}

	data->rtc->ops = &snvs_rtc_ops;
	data->rtc->range_max = U32_MAX;

	return devm_rtc_register_device(data->rtc);
}

static int __maybe_unused snvs_rtc_suspend_noirq(struct device *dev)
{
	struct snvs_rtc_data *data = dev_get_drvdata(dev);

	clk_disable(data->clk);

	return 0;
}

static int __maybe_unused snvs_rtc_resume_noirq(struct device *dev)
{
	struct snvs_rtc_data *data = dev_get_drvdata(dev);

	if (data->clk)
		return clk_enable(data->clk);

	return 0;
}

static const struct dev_pm_ops snvs_rtc_pm_ops = {
	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(snvs_rtc_suspend_noirq, snvs_rtc_resume_noirq)
};

static const struct of_device_id snvs_dt_ids[] = {
	{ .compatible = "fsl,sec-v4.0-mon-rtc-lp", },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, snvs_dt_ids);

static struct platform_driver snvs_rtc_driver = {
	.driver = {
		.name	= "snvs_rtc",
		.pm	= &snvs_rtc_pm_ops,
		.of_match_table = snvs_dt_ids,
	},
	.probe		= snvs_rtc_probe,
};
module_platform_driver(snvs_rtc_driver);

MODULE_AUTHOR("Freescale Semiconductor, Inc.");
MODULE_DESCRIPTION("Freescale SNVS RTC Driver");
MODULE_LICENSE("GPL");