xref: /linux/drivers/rtc/rtc-brcmstb-waketimer.c (revision 4ab5a5d2a4a2289c2af07accbec7170ca5671f41)
1 /*
2  * Copyright © 2014-2017 Broadcom
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11  * GNU General Public License for more details.
12  */
13 
14 #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
15 
16 #include <linux/clk.h>
17 #include <linux/device.h>
18 #include <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/interrupt.h>
21 #include <linux/io.h>
22 #include <linux/irqreturn.h>
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/of.h>
26 #include <linux/platform_device.h>
27 #include <linux/pm.h>
28 #include <linux/pm_wakeup.h>
29 #include <linux/reboot.h>
30 #include <linux/rtc.h>
31 #include <linux/stat.h>
32 #include <linux/suspend.h>
33 
34 struct brcmstb_waketmr {
35 	struct rtc_device *rtc;
36 	struct device *dev;
37 	void __iomem *base;
38 	int irq;
39 	struct notifier_block reboot_notifier;
40 	struct clk *clk;
41 	u32 rate;
42 };
43 
44 #define BRCMSTB_WKTMR_EVENT		0x00
45 #define BRCMSTB_WKTMR_COUNTER		0x04
46 #define BRCMSTB_WKTMR_ALARM		0x08
47 #define BRCMSTB_WKTMR_PRESCALER		0x0C
48 #define BRCMSTB_WKTMR_PRESCALER_VAL	0x10
49 
50 #define BRCMSTB_WKTMR_DEFAULT_FREQ	27000000
51 
52 static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
53 {
54 	writel_relaxed(1, timer->base + BRCMSTB_WKTMR_EVENT);
55 	(void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
56 }
57 
58 static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
59 				      unsigned int secs)
60 {
61 	brcmstb_waketmr_clear_alarm(timer);
62 
63 	/* Make sure we are actually counting in seconds */
64 	writel_relaxed(timer->rate, timer->base + BRCMSTB_WKTMR_PRESCALER);
65 
66 	writel_relaxed(secs + 1, timer->base + BRCMSTB_WKTMR_ALARM);
67 }
68 
69 static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
70 {
71 	struct brcmstb_waketmr *timer = data;
72 
73 	pm_wakeup_event(timer->dev, 0);
74 
75 	return IRQ_HANDLED;
76 }
77 
78 struct wktmr_time {
79 	u32 sec;
80 	u32 pre;
81 };
82 
83 static void wktmr_read(struct brcmstb_waketmr *timer,
84 		       struct wktmr_time *t)
85 {
86 	u32 tmp;
87 
88 	do {
89 		t->sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
90 		tmp = readl_relaxed(timer->base + BRCMSTB_WKTMR_PRESCALER_VAL);
91 	} while (tmp >= timer->rate);
92 
93 	t->pre = timer->rate - tmp;
94 }
95 
96 static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
97 {
98 	struct device *dev = timer->dev;
99 	int ret = 0;
100 
101 	if (device_may_wakeup(dev)) {
102 		ret = enable_irq_wake(timer->irq);
103 		if (ret) {
104 			dev_err(dev, "failed to enable wake-up interrupt\n");
105 			return ret;
106 		}
107 	}
108 
109 	return ret;
110 }
111 
112 /* If enabled as a wakeup-source, arm the timer when powering off */
113 static int brcmstb_waketmr_reboot(struct notifier_block *nb,
114 		unsigned long action, void *data)
115 {
116 	struct brcmstb_waketmr *timer;
117 
118 	timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);
119 
120 	/* Set timer for cold boot */
121 	if (action == SYS_POWER_OFF)
122 		brcmstb_waketmr_prepare_suspend(timer);
123 
124 	return NOTIFY_DONE;
125 }
126 
127 static int brcmstb_waketmr_gettime(struct device *dev,
128 				   struct rtc_time *tm)
129 {
130 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
131 	struct wktmr_time now;
132 
133 	wktmr_read(timer, &now);
134 
135 	rtc_time_to_tm(now.sec, tm);
136 
137 	return 0;
138 }
139 
140 static int brcmstb_waketmr_settime(struct device *dev,
141 				   struct rtc_time *tm)
142 {
143 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
144 	time64_t sec;
145 
146 	sec = rtc_tm_to_time64(tm);
147 
148 	writel_relaxed(sec, timer->base + BRCMSTB_WKTMR_COUNTER);
149 
150 	return 0;
151 }
152 
153 static int brcmstb_waketmr_getalarm(struct device *dev,
154 				    struct rtc_wkalrm *alarm)
155 {
156 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
157 	time64_t sec;
158 	u32 reg;
159 
160 	sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_ALARM);
161 	if (sec != 0) {
162 		/* Alarm is enabled */
163 		alarm->enabled = 1;
164 		rtc_time64_to_tm(sec, &alarm->time);
165 	}
166 
167 	reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
168 	alarm->pending = !!(reg & 1);
169 
170 	return 0;
171 }
172 
173 static int brcmstb_waketmr_setalarm(struct device *dev,
174 				     struct rtc_wkalrm *alarm)
175 {
176 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
177 	time64_t sec;
178 
179 	if (alarm->enabled)
180 		sec = rtc_tm_to_time64(&alarm->time);
181 	else
182 		sec = 0;
183 
184 	brcmstb_waketmr_set_alarm(timer, sec);
185 
186 	return 0;
187 }
188 
189 /*
190  * Does not do much but keep the RTC class happy. We always support
191  * alarms.
192  */
193 static int brcmstb_waketmr_alarm_enable(struct device *dev,
194 					unsigned int enabled)
195 {
196 	return 0;
197 }
198 
199 static const struct rtc_class_ops brcmstb_waketmr_ops = {
200 	.read_time	= brcmstb_waketmr_gettime,
201 	.set_time	= brcmstb_waketmr_settime,
202 	.read_alarm	= brcmstb_waketmr_getalarm,
203 	.set_alarm	= brcmstb_waketmr_setalarm,
204 	.alarm_irq_enable = brcmstb_waketmr_alarm_enable,
205 };
206 
207 static int brcmstb_waketmr_probe(struct platform_device *pdev)
208 {
209 	struct device *dev = &pdev->dev;
210 	struct brcmstb_waketmr *timer;
211 	struct resource *res;
212 	int ret;
213 
214 	timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
215 	if (!timer)
216 		return -ENOMEM;
217 
218 	platform_set_drvdata(pdev, timer);
219 	timer->dev = dev;
220 
221 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
222 	timer->base = devm_ioremap_resource(dev, res);
223 	if (IS_ERR(timer->base))
224 		return PTR_ERR(timer->base);
225 
226 	timer->rtc = devm_rtc_allocate_device(dev);
227 	if (IS_ERR(timer->rtc))
228 		return PTR_ERR(timer->rtc);
229 
230 	/*
231 	 * Set wakeup capability before requesting wakeup interrupt, so we can
232 	 * process boot-time "wakeups" (e.g., from S5 soft-off)
233 	 */
234 	device_set_wakeup_capable(dev, true);
235 	device_wakeup_enable(dev);
236 
237 	timer->irq = platform_get_irq(pdev, 0);
238 	if (timer->irq < 0)
239 		return -ENODEV;
240 
241 	timer->clk = devm_clk_get(dev, NULL);
242 	if (!IS_ERR(timer->clk)) {
243 		ret = clk_prepare_enable(timer->clk);
244 		if (ret)
245 			return ret;
246 		timer->rate = clk_get_rate(timer->clk);
247 		if (!timer->rate)
248 			timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
249 	} else {
250 		timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
251 		timer->clk = NULL;
252 	}
253 
254 	ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
255 			       "brcmstb-waketimer", timer);
256 	if (ret < 0)
257 		goto err_clk;
258 
259 	timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
260 	register_reboot_notifier(&timer->reboot_notifier);
261 
262 	timer->rtc->ops = &brcmstb_waketmr_ops;
263 	timer->rtc->range_max = U32_MAX;
264 
265 	ret = rtc_register_device(timer->rtc);
266 	if (ret) {
267 		dev_err(dev, "unable to register device\n");
268 		goto err_notifier;
269 	}
270 
271 	dev_info(dev, "registered, with irq %d\n", timer->irq);
272 
273 	return 0;
274 
275 err_notifier:
276 	unregister_reboot_notifier(&timer->reboot_notifier);
277 
278 err_clk:
279 	if (timer->clk)
280 		clk_disable_unprepare(timer->clk);
281 
282 	return ret;
283 }
284 
285 static int brcmstb_waketmr_remove(struct platform_device *pdev)
286 {
287 	struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);
288 
289 	unregister_reboot_notifier(&timer->reboot_notifier);
290 
291 	return 0;
292 }
293 
294 #ifdef CONFIG_PM_SLEEP
295 static int brcmstb_waketmr_suspend(struct device *dev)
296 {
297 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
298 
299 	return brcmstb_waketmr_prepare_suspend(timer);
300 }
301 
302 static int brcmstb_waketmr_resume(struct device *dev)
303 {
304 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
305 	int ret;
306 
307 	if (!device_may_wakeup(dev))
308 		return 0;
309 
310 	ret = disable_irq_wake(timer->irq);
311 
312 	brcmstb_waketmr_clear_alarm(timer);
313 
314 	return ret;
315 }
316 #endif /* CONFIG_PM_SLEEP */
317 
318 static SIMPLE_DEV_PM_OPS(brcmstb_waketmr_pm_ops,
319 			 brcmstb_waketmr_suspend, brcmstb_waketmr_resume);
320 
321 static const struct of_device_id brcmstb_waketmr_of_match[] = {
322 	{ .compatible = "brcm,brcmstb-waketimer" },
323 	{ /* sentinel */ },
324 };
325 
326 static struct platform_driver brcmstb_waketmr_driver = {
327 	.probe			= brcmstb_waketmr_probe,
328 	.remove			= brcmstb_waketmr_remove,
329 	.driver = {
330 		.name		= "brcmstb-waketimer",
331 		.pm		= &brcmstb_waketmr_pm_ops,
332 		.of_match_table	= of_match_ptr(brcmstb_waketmr_of_match),
333 	}
334 };
335 module_platform_driver(brcmstb_waketmr_driver);
336 
337 MODULE_LICENSE("GPL v2");
338 MODULE_AUTHOR("Brian Norris");
339 MODULE_AUTHOR("Markus Mayer");
340 MODULE_DESCRIPTION("Wake-up timer driver for STB chips");
341