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 
41 struct 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 
st_rtc_set_hw_alarm(struct st_rtc * rtc,unsigned long msb,unsigned long lsb)52 static 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 
st_rtc_handler(int this_irq,void * data)70 static 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 
st_rtc_read_time(struct device * dev,struct rtc_time * tm)79 static 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 
st_rtc_set_time(struct device * dev,struct rtc_time * tm)102 static 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 
st_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * wkalrm)123 static 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 
st_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)137 static 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 
st_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * t)152 static 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 
176 static 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 
st_rtc_probe(struct platform_device * pdev)184 static 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
st_rtc_suspend(struct device * dev)258 static 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 
st_rtc_resume(struct device * dev)272 static 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 
294 static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
295 
296 static const struct of_device_id st_rtc_match[] = {
297 	{ .compatible = "st,stih407-lpc" },
298 	{}
299 };
300 MODULE_DEVICE_TABLE(of, st_rtc_match);
301 
302 static 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 
311 module_platform_driver(st_rtc_platform_driver);
312 
313 MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
314 MODULE_AUTHOR("David Paris <david.paris@st.com>");
315 MODULE_LICENSE("GPL");
316