1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright © 2014-2017 Broadcom
4  */
5 
6 #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
7 
8 #include <linux/clk.h>
9 #include <linux/device.h>
10 #include <linux/err.h>
11 #include <linux/init.h>
12 #include <linux/interrupt.h>
13 #include <linux/io.h>
14 #include <linux/irqreturn.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/platform_device.h>
19 #include <linux/pm.h>
20 #include <linux/pm_wakeup.h>
21 #include <linux/reboot.h>
22 #include <linux/rtc.h>
23 #include <linux/stat.h>
24 #include <linux/suspend.h>
25 
26 struct brcmstb_waketmr {
27 	struct rtc_device *rtc;
28 	struct device *dev;
29 	void __iomem *base;
30 	int irq;
31 	struct notifier_block reboot_notifier;
32 	struct clk *clk;
33 	u32 rate;
34 };
35 
36 #define BRCMSTB_WKTMR_EVENT		0x00
37 #define BRCMSTB_WKTMR_COUNTER		0x04
38 #define BRCMSTB_WKTMR_ALARM		0x08
39 #define BRCMSTB_WKTMR_PRESCALER		0x0C
40 #define BRCMSTB_WKTMR_PRESCALER_VAL	0x10
41 
42 #define BRCMSTB_WKTMR_DEFAULT_FREQ	27000000
43 
44 static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
45 {
46 	writel_relaxed(1, timer->base + BRCMSTB_WKTMR_EVENT);
47 	(void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
48 }
49 
50 static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
51 				      unsigned int secs)
52 {
53 	brcmstb_waketmr_clear_alarm(timer);
54 
55 	/* Make sure we are actually counting in seconds */
56 	writel_relaxed(timer->rate, timer->base + BRCMSTB_WKTMR_PRESCALER);
57 
58 	writel_relaxed(secs + 1, timer->base + BRCMSTB_WKTMR_ALARM);
59 }
60 
61 static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
62 {
63 	struct brcmstb_waketmr *timer = data;
64 
65 	pm_wakeup_event(timer->dev, 0);
66 
67 	return IRQ_HANDLED;
68 }
69 
70 struct wktmr_time {
71 	u32 sec;
72 	u32 pre;
73 };
74 
75 static void wktmr_read(struct brcmstb_waketmr *timer,
76 		       struct wktmr_time *t)
77 {
78 	u32 tmp;
79 
80 	do {
81 		t->sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
82 		tmp = readl_relaxed(timer->base + BRCMSTB_WKTMR_PRESCALER_VAL);
83 	} while (tmp >= timer->rate);
84 
85 	t->pre = timer->rate - tmp;
86 }
87 
88 static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
89 {
90 	struct device *dev = timer->dev;
91 	int ret = 0;
92 
93 	if (device_may_wakeup(dev)) {
94 		ret = enable_irq_wake(timer->irq);
95 		if (ret) {
96 			dev_err(dev, "failed to enable wake-up interrupt\n");
97 			return ret;
98 		}
99 	}
100 
101 	return ret;
102 }
103 
104 /* If enabled as a wakeup-source, arm the timer when powering off */
105 static int brcmstb_waketmr_reboot(struct notifier_block *nb,
106 		unsigned long action, void *data)
107 {
108 	struct brcmstb_waketmr *timer;
109 
110 	timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);
111 
112 	/* Set timer for cold boot */
113 	if (action == SYS_POWER_OFF)
114 		brcmstb_waketmr_prepare_suspend(timer);
115 
116 	return NOTIFY_DONE;
117 }
118 
119 static int brcmstb_waketmr_gettime(struct device *dev,
120 				   struct rtc_time *tm)
121 {
122 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
123 	struct wktmr_time now;
124 
125 	wktmr_read(timer, &now);
126 
127 	rtc_time64_to_tm(now.sec, tm);
128 
129 	return 0;
130 }
131 
132 static int brcmstb_waketmr_settime(struct device *dev,
133 				   struct rtc_time *tm)
134 {
135 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
136 	time64_t sec;
137 
138 	sec = rtc_tm_to_time64(tm);
139 
140 	writel_relaxed(sec, timer->base + BRCMSTB_WKTMR_COUNTER);
141 
142 	return 0;
143 }
144 
145 static int brcmstb_waketmr_getalarm(struct device *dev,
146 				    struct rtc_wkalrm *alarm)
147 {
148 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
149 	time64_t sec;
150 	u32 reg;
151 
152 	sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_ALARM);
153 	if (sec != 0) {
154 		/* Alarm is enabled */
155 		alarm->enabled = 1;
156 		rtc_time64_to_tm(sec, &alarm->time);
157 	}
158 
159 	reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
160 	alarm->pending = !!(reg & 1);
161 
162 	return 0;
163 }
164 
165 static int brcmstb_waketmr_setalarm(struct device *dev,
166 				     struct rtc_wkalrm *alarm)
167 {
168 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
169 	time64_t sec;
170 
171 	if (alarm->enabled)
172 		sec = rtc_tm_to_time64(&alarm->time);
173 	else
174 		sec = 0;
175 
176 	brcmstb_waketmr_set_alarm(timer, sec);
177 
178 	return 0;
179 }
180 
181 /*
182  * Does not do much but keep the RTC class happy. We always support
183  * alarms.
184  */
185 static int brcmstb_waketmr_alarm_enable(struct device *dev,
186 					unsigned int enabled)
187 {
188 	return 0;
189 }
190 
191 static const struct rtc_class_ops brcmstb_waketmr_ops = {
192 	.read_time	= brcmstb_waketmr_gettime,
193 	.set_time	= brcmstb_waketmr_settime,
194 	.read_alarm	= brcmstb_waketmr_getalarm,
195 	.set_alarm	= brcmstb_waketmr_setalarm,
196 	.alarm_irq_enable = brcmstb_waketmr_alarm_enable,
197 };
198 
199 static int brcmstb_waketmr_probe(struct platform_device *pdev)
200 {
201 	struct device *dev = &pdev->dev;
202 	struct brcmstb_waketmr *timer;
203 	struct resource *res;
204 	int ret;
205 
206 	timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
207 	if (!timer)
208 		return -ENOMEM;
209 
210 	platform_set_drvdata(pdev, timer);
211 	timer->dev = dev;
212 
213 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
214 	timer->base = devm_ioremap_resource(dev, res);
215 	if (IS_ERR(timer->base))
216 		return PTR_ERR(timer->base);
217 
218 	timer->rtc = devm_rtc_allocate_device(dev);
219 	if (IS_ERR(timer->rtc))
220 		return PTR_ERR(timer->rtc);
221 
222 	/*
223 	 * Set wakeup capability before requesting wakeup interrupt, so we can
224 	 * process boot-time "wakeups" (e.g., from S5 soft-off)
225 	 */
226 	device_set_wakeup_capable(dev, true);
227 	device_wakeup_enable(dev);
228 
229 	timer->irq = platform_get_irq(pdev, 0);
230 	if (timer->irq < 0)
231 		return -ENODEV;
232 
233 	timer->clk = devm_clk_get(dev, NULL);
234 	if (!IS_ERR(timer->clk)) {
235 		ret = clk_prepare_enable(timer->clk);
236 		if (ret)
237 			return ret;
238 		timer->rate = clk_get_rate(timer->clk);
239 		if (!timer->rate)
240 			timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
241 	} else {
242 		timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
243 		timer->clk = NULL;
244 	}
245 
246 	ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
247 			       "brcmstb-waketimer", timer);
248 	if (ret < 0)
249 		goto err_clk;
250 
251 	timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
252 	register_reboot_notifier(&timer->reboot_notifier);
253 
254 	timer->rtc->ops = &brcmstb_waketmr_ops;
255 	timer->rtc->range_max = U32_MAX;
256 
257 	ret = rtc_register_device(timer->rtc);
258 	if (ret)
259 		goto err_notifier;
260 
261 	dev_info(dev, "registered, with irq %d\n", timer->irq);
262 
263 	return 0;
264 
265 err_notifier:
266 	unregister_reboot_notifier(&timer->reboot_notifier);
267 
268 err_clk:
269 	if (timer->clk)
270 		clk_disable_unprepare(timer->clk);
271 
272 	return ret;
273 }
274 
275 static int brcmstb_waketmr_remove(struct platform_device *pdev)
276 {
277 	struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);
278 
279 	unregister_reboot_notifier(&timer->reboot_notifier);
280 
281 	return 0;
282 }
283 
284 #ifdef CONFIG_PM_SLEEP
285 static int brcmstb_waketmr_suspend(struct device *dev)
286 {
287 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
288 
289 	return brcmstb_waketmr_prepare_suspend(timer);
290 }
291 
292 static int brcmstb_waketmr_resume(struct device *dev)
293 {
294 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
295 	int ret;
296 
297 	if (!device_may_wakeup(dev))
298 		return 0;
299 
300 	ret = disable_irq_wake(timer->irq);
301 
302 	brcmstb_waketmr_clear_alarm(timer);
303 
304 	return ret;
305 }
306 #endif /* CONFIG_PM_SLEEP */
307 
308 static SIMPLE_DEV_PM_OPS(brcmstb_waketmr_pm_ops,
309 			 brcmstb_waketmr_suspend, brcmstb_waketmr_resume);
310 
311 static const struct of_device_id brcmstb_waketmr_of_match[] = {
312 	{ .compatible = "brcm,brcmstb-waketimer" },
313 	{ /* sentinel */ },
314 };
315 
316 static struct platform_driver brcmstb_waketmr_driver = {
317 	.probe			= brcmstb_waketmr_probe,
318 	.remove			= brcmstb_waketmr_remove,
319 	.driver = {
320 		.name		= "brcmstb-waketimer",
321 		.pm		= &brcmstb_waketmr_pm_ops,
322 		.of_match_table	= of_match_ptr(brcmstb_waketmr_of_match),
323 	}
324 };
325 module_platform_driver(brcmstb_waketmr_driver);
326 
327 MODULE_LICENSE("GPL v2");
328 MODULE_AUTHOR("Brian Norris");
329 MODULE_AUTHOR("Markus Mayer");
330 MODULE_DESCRIPTION("Wake-up timer driver for STB chips");
331