1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
4 *
5 * Copyright (C) 2014 STMicroelectronics Limited
6 *
7 * Author: David Paris <david.paris@st.com> for STMicroelectronics
8 *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
9 *
10 * Based on the original driver written by Stuart Menefy.
11 */
12
13#include <linux/clk.h>
14#include <linux/delay.h>
15#include <linux/init.h>
16#include <linux/io.h>
17#include <linux/irq.h>
18#include <linux/kernel.h>
19#include <linux/module.h>
20#include <linux/of.h>
21#include <linux/of_irq.h>
22#include <linux/platform_device.h>
23#include <linux/rtc.h>
24
25#include <dt-bindings/mfd/st-lpc.h>
26
27/* Low Power Timer */
28#define LPC_LPT_LSB_OFF		0x400
29#define LPC_LPT_MSB_OFF		0x404
30#define LPC_LPT_START_OFF	0x408
31
32/* Low Power Alarm */
33#define LPC_LPA_LSB_OFF		0x410
34#define LPC_LPA_MSB_OFF		0x414
35#define LPC_LPA_START_OFF	0x418
36
37/* LPC as WDT */
38#define LPC_WDT_OFF		0x510
39#define LPC_WDT_FLAG_OFF	0x514
40
41struct st_rtc {
42	struct rtc_device *rtc_dev;
43	struct rtc_wkalrm alarm;
44	struct clk *clk;
45	unsigned long clkrate;
46	void __iomem *ioaddr;
47	bool irq_enabled:1;
48	spinlock_t lock;
49	short irq;
50};
51
52static void st_rtc_set_hw_alarm(struct st_rtc *rtc,
53				unsigned long msb, unsigned long  lsb)
54{
55	unsigned long flags;
56
57	spin_lock_irqsave(&rtc->lock, flags);
58
59	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
60
61	writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
62	writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
63	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
64
65	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
66
67	spin_unlock_irqrestore(&rtc->lock, flags);
68}
69
70static irqreturn_t st_rtc_handler(int this_irq, void *data)
71{
72	struct st_rtc *rtc = (struct st_rtc *)data;
73
74	rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);
75
76	return IRQ_HANDLED;
77}
78
79static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)
80{
81	struct st_rtc *rtc = dev_get_drvdata(dev);
82	unsigned long lpt_lsb, lpt_msb;
83	unsigned long long lpt;
84	unsigned long flags;
85
86	spin_lock_irqsave(&rtc->lock, flags);
87
88	do {
89		lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF);
90		lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF);
91	} while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);
92
93	spin_unlock_irqrestore(&rtc->lock, flags);
94
95	lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
96	do_div(lpt, rtc->clkrate);
97	rtc_time64_to_tm(lpt, tm);
98
99	return 0;
100}
101
102static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)
103{
104	struct st_rtc *rtc = dev_get_drvdata(dev);
105	unsigned long long lpt, secs;
106	unsigned long flags;
107
108	secs = rtc_tm_to_time64(tm);
109
110	lpt = (unsigned long long)secs * rtc->clkrate;
111
112	spin_lock_irqsave(&rtc->lock, flags);
113
114	writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
115	writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
116	writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);
117
118	spin_unlock_irqrestore(&rtc->lock, flags);
119
120	return 0;
121}
122
123static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
124{
125	struct st_rtc *rtc = dev_get_drvdata(dev);
126	unsigned long flags;
127
128	spin_lock_irqsave(&rtc->lock, flags);
129
130	memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
131
132	spin_unlock_irqrestore(&rtc->lock, flags);
133
134	return 0;
135}
136
137static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
138{
139	struct st_rtc *rtc = dev_get_drvdata(dev);
140
141	if (enabled && !rtc->irq_enabled) {
142		enable_irq(rtc->irq);
143		rtc->irq_enabled = true;
144	} else if (!enabled && rtc->irq_enabled) {
145		disable_irq(rtc->irq);
146		rtc->irq_enabled = false;
147	}
148
149	return 0;
150}
151
152static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
153{
154	struct st_rtc *rtc = dev_get_drvdata(dev);
155	struct rtc_time now;
156	unsigned long long now_secs;
157	unsigned long long alarm_secs;
158	unsigned long long lpa;
159
160	st_rtc_read_time(dev, &now);
161	now_secs = rtc_tm_to_time64(&now);
162	alarm_secs = rtc_tm_to_time64(&t->time);
163
164	memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
165
166	/* Now many secs to fire */
167	alarm_secs -= now_secs;
168	lpa = (unsigned long long)alarm_secs * rtc->clkrate;
169
170	st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
171	st_rtc_alarm_irq_enable(dev, t->enabled);
172
173	return 0;
174}
175
176static const struct rtc_class_ops st_rtc_ops = {
177	.read_time		= st_rtc_read_time,
178	.set_time		= st_rtc_set_time,
179	.read_alarm		= st_rtc_read_alarm,
180	.set_alarm		= st_rtc_set_alarm,
181	.alarm_irq_enable	= st_rtc_alarm_irq_enable,
182};
183
184static int st_rtc_probe(struct platform_device *pdev)
185{
186	struct device_node *np = pdev->dev.of_node;
187	struct st_rtc *rtc;
188	uint32_t mode;
189	int ret = 0;
190
191	ret = of_property_read_u32(np, "st,lpc-mode", &mode);
192	if (ret) {
193		dev_err(&pdev->dev, "An LPC mode must be provided\n");
194		return -EINVAL;
195	}
196
197	/* LPC can either run as a Clocksource or in RTC or WDT mode */
198	if (mode != ST_LPC_MODE_RTC)
199		return -ENODEV;
200
201	rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
202	if (!rtc)
203		return -ENOMEM;
204
205	rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
206	if (IS_ERR(rtc->rtc_dev))
207		return PTR_ERR(rtc->rtc_dev);
208
209	spin_lock_init(&rtc->lock);
210
211	rtc->ioaddr = devm_platform_ioremap_resource(pdev, 0);
212	if (IS_ERR(rtc->ioaddr))
213		return PTR_ERR(rtc->ioaddr);
214
215	rtc->irq = irq_of_parse_and_map(np, 0);
216	if (!rtc->irq) {
217		dev_err(&pdev->dev, "IRQ missing or invalid\n");
218		return -EINVAL;
219	}
220
221	ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,
222			       pdev->name, rtc);
223	if (ret) {
224		dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);
225		return ret;
226	}
227
228	enable_irq_wake(rtc->irq);
229	disable_irq(rtc->irq);
230
231	rtc->clk = devm_clk_get_enabled(&pdev->dev, NULL);
232	if (IS_ERR(rtc->clk))
233		return dev_err_probe(&pdev->dev, PTR_ERR(rtc->clk),
234				     "Unable to request clock\n");
235
236	rtc->clkrate = clk_get_rate(rtc->clk);
237	if (!rtc->clkrate) {
238		dev_err(&pdev->dev, "Unable to fetch clock rate\n");
239		return -EINVAL;
240	}
241
242	device_set_wakeup_capable(&pdev->dev, 1);
243
244	platform_set_drvdata(pdev, rtc);
245
246	rtc->rtc_dev->ops = &st_rtc_ops;
247	rtc->rtc_dev->range_max = U64_MAX;
248	do_div(rtc->rtc_dev->range_max, rtc->clkrate);
249
250	ret = devm_rtc_register_device(rtc->rtc_dev);
251	if (ret)
252		return ret;
253
254	return 0;
255}
256
257#ifdef CONFIG_PM_SLEEP
258static int st_rtc_suspend(struct device *dev)
259{
260	struct st_rtc *rtc = dev_get_drvdata(dev);
261
262	if (device_may_wakeup(dev))
263		return 0;
264
265	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
266	writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);
267	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
268
269	return 0;
270}
271
272static int st_rtc_resume(struct device *dev)
273{
274	struct st_rtc *rtc = dev_get_drvdata(dev);
275
276	rtc_alarm_irq_enable(rtc->rtc_dev, 0);
277
278	/*
279	 * clean 'rtc->alarm' to allow a new
280	 * .set_alarm to the upper RTC layer
281	 */
282	memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
283
284	writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
285	writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
286	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
287	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
288	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
289
290	return 0;
291}
292#endif
293
294static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
295
296static const struct of_device_id st_rtc_match[] = {
297	{ .compatible = "st,stih407-lpc" },
298	{}
299};
300MODULE_DEVICE_TABLE(of, st_rtc_match);
301
302static struct platform_driver st_rtc_platform_driver = {
303	.driver = {
304		.name = "st-lpc-rtc",
305		.pm = &st_rtc_pm_ops,
306		.of_match_table = st_rtc_match,
307	},
308	.probe = st_rtc_probe,
309};
310
311module_platform_driver(st_rtc_platform_driver);
312
313MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
314MODULE_AUTHOR("David Paris <david.paris@st.com>");
315MODULE_LICENSE("GPL");
316