summaryrefslogtreecommitdiffstats
path: root/drivers/rtc/rtc-st-lpc.c
blob: d04d46f9cc65a0c311f025ac4c27d38f84a9251d (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
 *
 * Copyright (C) 2014 STMicroelectronics Limited
 *
 * Author: David Paris <david.paris@st.com> for STMicroelectronics
 *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
 *
 * Based on the original driver written by Stuart Menefy.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>

#include <dt-bindings/mfd/st-lpc.h>

/* Low Power Timer */
#define LPC_LPT_LSB_OFF		0x400
#define LPC_LPT_MSB_OFF		0x404
#define LPC_LPT_START_OFF	0x408

/* Low Power Alarm */
#define LPC_LPA_LSB_OFF		0x410
#define LPC_LPA_MSB_OFF		0x414
#define LPC_LPA_START_OFF	0x418

/* LPC as WDT */
#define LPC_WDT_OFF		0x510
#define LPC_WDT_FLAG_OFF	0x514

struct st_rtc {
	struct rtc_device *rtc_dev;
	struct rtc_wkalrm alarm;
	struct clk *clk;
	unsigned long clkrate;
	void __iomem *ioaddr;
	bool irq_enabled:1;
	spinlock_t lock;
	short irq;
};

static void st_rtc_set_hw_alarm(struct st_rtc *rtc,
				unsigned long msb, unsigned long  lsb)
{
	unsigned long flags;

	spin_lock_irqsave(&rtc->lock, flags);

	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);

	writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
	writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);

	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);

	spin_unlock_irqrestore(&rtc->lock, flags);
}

static irqreturn_t st_rtc_handler(int this_irq, void *data)
{
	struct st_rtc *rtc = (struct st_rtc *)data;

	rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);

	return IRQ_HANDLED;
}

static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct st_rtc *rtc = dev_get_drvdata(dev);
	unsigned long lpt_lsb, lpt_msb;
	unsigned long long lpt;
	unsigned long flags;

	spin_lock_irqsave(&rtc->lock, flags);

	do {
		lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF);
		lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF);
	} while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);

	spin_unlock_irqrestore(&rtc->lock, flags);

	lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
	do_div(lpt, rtc->clkrate);
	rtc_time64_to_tm(lpt, tm);

	return 0;
}

static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct st_rtc *rtc = dev_get_drvdata(dev);
	unsigned long long lpt, secs;
	unsigned long flags;

	secs = rtc_tm_to_time64(tm);

	lpt = (unsigned long long)secs * rtc->clkrate;

	spin_lock_irqsave(&rtc->lock, flags);

	writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
	writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
	writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);

	spin_unlock_irqrestore(&rtc->lock, flags);

	return 0;
}

static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
	struct st_rtc *rtc = dev_get_drvdata(dev);
	unsigned long flags;

	spin_lock_irqsave(&rtc->lock, flags);

	memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));

	spin_unlock_irqrestore(&rtc->lock, flags);

	return 0;
}

static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
	struct st_rtc *rtc = dev_get_drvdata(dev);

	if (enabled && !rtc->irq_enabled) {
		enable_irq(rtc->irq);
		rtc->irq_enabled = true;
	} else if (!enabled && rtc->irq_enabled) {
		disable_irq(rtc->irq);
		rtc->irq_enabled = false;
	}

	return 0;
}

static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
{
	struct st_rtc *rtc = dev_get_drvdata(dev);
	struct rtc_time now;
	unsigned long long now_secs;
	unsigned long long alarm_secs;
	unsigned long long lpa;

	st_rtc_read_time(dev, &now);
	now_secs = rtc_tm_to_time64(&now);
	alarm_secs = rtc_tm_to_time64(&t->time);

	memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));

	/* Now many secs to fire */
	alarm_secs -= now_secs;
	lpa = (unsigned long long)alarm_secs * rtc->clkrate;

	st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
	st_rtc_alarm_irq_enable(dev, t->enabled);

	return 0;
}

static const struct rtc_class_ops st_rtc_ops = {
	.read_time		= st_rtc_read_time,
	.set_time		= st_rtc_set_time,
	.read_alarm		= st_rtc_read_alarm,
	.set_alarm		= st_rtc_set_alarm,
	.alarm_irq_enable	= st_rtc_alarm_irq_enable,
};

static int st_rtc_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct st_rtc *rtc;
	uint32_t mode;
	int ret = 0;

	ret = of_property_read_u32(np, "st,lpc-mode", &mode);
	if (ret) {
		dev_err(&pdev->dev, "An LPC mode must be provided\n");
		return -EINVAL;
	}

	/* LPC can either run as a Clocksource or in RTC or WDT mode */
	if (mode != ST_LPC_MODE_RTC)
		return -ENODEV;

	rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
	if (!rtc)
		return -ENOMEM;

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

	spin_lock_init(&rtc->lock);

	rtc->ioaddr = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(rtc->ioaddr))
		return PTR_ERR(rtc->ioaddr);

	rtc->irq = irq_of_parse_and_map(np, 0);
	if (!rtc->irq) {
		dev_err(&pdev->dev, "IRQ missing or invalid\n");
		return -EINVAL;
	}

	ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,
			       pdev->name, rtc);
	if (ret) {
		dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);
		return ret;
	}

	enable_irq_wake(rtc->irq);
	disable_irq(rtc->irq);

	rtc->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(rtc->clk)) {
		dev_err(&pdev->dev, "Unable to request clock\n");
		return PTR_ERR(rtc->clk);
	}

	clk_prepare_enable(rtc->clk);

	rtc->clkrate = clk_get_rate(rtc->clk);
	if (!rtc->clkrate) {
		clk_disable_unprepare(rtc->clk);
		dev_err(&pdev->dev, "Unable to fetch clock rate\n");
		return -EINVAL;
	}

	device_set_wakeup_capable(&pdev->dev, 1);

	platform_set_drvdata(pdev, rtc);

	rtc->rtc_dev->ops = &st_rtc_ops;
	rtc->rtc_dev->range_max = U64_MAX;
	do_div(rtc->rtc_dev->range_max, rtc->clkrate);

	ret = devm_rtc_register_device(rtc->rtc_dev);
	if (ret) {
		clk_disable_unprepare(rtc->clk);
		return ret;
	}

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int st_rtc_suspend(struct device *dev)
{
	struct st_rtc *rtc = dev_get_drvdata(dev);

	if (device_may_wakeup(dev))
		return 0;

	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
	writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);
	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);

	return 0;
}

static int st_rtc_resume(struct device *dev)
{
	struct st_rtc *rtc = dev_get_drvdata(dev);

	rtc_alarm_irq_enable(rtc->rtc_dev, 0);

	/*
	 * clean 'rtc->alarm' to allow a new
	 * .set_alarm to the upper RTC layer
	 */
	memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));

	writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
	writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);

	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);

static const struct of_device_id st_rtc_match[] = {
	{ .compatible = "st,stih407-lpc" },
	{}
};
MODULE_DEVICE_TABLE(of, st_rtc_match);

static struct platform_driver st_rtc_platform_driver = {
	.driver = {
		.name = "st-lpc-rtc",
		.pm = &st_rtc_pm_ops,
		.of_match_table = st_rtc_match,
	},
	.probe = st_rtc_probe,
};

module_platform_driver(st_rtc_platform_driver);

MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
MODULE_AUTHOR("David Paris <david.paris@st.com>");
MODULE_LICENSE("GPL");