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 
brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr * timer)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 
brcmstb_waketmr_set_alarm(struct brcmstb_waketmr * timer,unsigned int secs)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 
brcmstb_waketmr_irq(int irq,void * data)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 
wktmr_read(struct brcmstb_waketmr * timer,struct wktmr_time * t)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 
brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr * timer)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 */
brcmstb_waketmr_reboot(struct notifier_block * nb,unsigned long action,void * data)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 
brcmstb_waketmr_gettime(struct device * dev,struct rtc_time * tm)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 
brcmstb_waketmr_settime(struct device * dev,struct rtc_time * tm)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 
brcmstb_waketmr_getalarm(struct device * dev,struct rtc_wkalrm * alarm)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 
brcmstb_waketmr_setalarm(struct device * dev,struct rtc_wkalrm * alarm)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  */
brcmstb_waketmr_alarm_enable(struct device * dev,unsigned int enabled)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 
brcmstb_waketmr_probe(struct platform_device * pdev)199 static int brcmstb_waketmr_probe(struct platform_device *pdev)
200 {
201 	struct device *dev = &pdev->dev;
202 	struct brcmstb_waketmr *timer;
203 	int ret;
204 
205 	timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
206 	if (!timer)
207 		return -ENOMEM;
208 
209 	platform_set_drvdata(pdev, timer);
210 	timer->dev = dev;
211 
212 	timer->base = devm_platform_ioremap_resource(pdev, 0);
213 	if (IS_ERR(timer->base))
214 		return PTR_ERR(timer->base);
215 
216 	timer->rtc = devm_rtc_allocate_device(dev);
217 	if (IS_ERR(timer->rtc))
218 		return PTR_ERR(timer->rtc);
219 
220 	/*
221 	 * Set wakeup capability before requesting wakeup interrupt, so we can
222 	 * process boot-time "wakeups" (e.g., from S5 soft-off)
223 	 */
224 	device_set_wakeup_capable(dev, true);
225 	device_wakeup_enable(dev);
226 
227 	timer->irq = platform_get_irq(pdev, 0);
228 	if (timer->irq < 0)
229 		return -ENODEV;
230 
231 	timer->clk = devm_clk_get(dev, NULL);
232 	if (!IS_ERR(timer->clk)) {
233 		ret = clk_prepare_enable(timer->clk);
234 		if (ret)
235 			return ret;
236 		timer->rate = clk_get_rate(timer->clk);
237 		if (!timer->rate)
238 			timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
239 	} else {
240 		timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
241 		timer->clk = NULL;
242 	}
243 
244 	ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
245 			       "brcmstb-waketimer", timer);
246 	if (ret < 0)
247 		goto err_clk;
248 
249 	timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
250 	register_reboot_notifier(&timer->reboot_notifier);
251 
252 	timer->rtc->ops = &brcmstb_waketmr_ops;
253 	timer->rtc->range_max = U32_MAX;
254 
255 	ret = devm_rtc_register_device(timer->rtc);
256 	if (ret)
257 		goto err_notifier;
258 
259 	dev_info(dev, "registered, with irq %d\n", timer->irq);
260 
261 	return 0;
262 
263 err_notifier:
264 	unregister_reboot_notifier(&timer->reboot_notifier);
265 
266 err_clk:
267 	clk_disable_unprepare(timer->clk);
268 
269 	return ret;
270 }
271 
brcmstb_waketmr_remove(struct platform_device * pdev)272 static int brcmstb_waketmr_remove(struct platform_device *pdev)
273 {
274 	struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);
275 
276 	unregister_reboot_notifier(&timer->reboot_notifier);
277 	clk_disable_unprepare(timer->clk);
278 
279 	return 0;
280 }
281 
282 #ifdef CONFIG_PM_SLEEP
brcmstb_waketmr_suspend(struct device * dev)283 static int brcmstb_waketmr_suspend(struct device *dev)
284 {
285 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
286 
287 	return brcmstb_waketmr_prepare_suspend(timer);
288 }
289 
brcmstb_waketmr_resume(struct device * dev)290 static int brcmstb_waketmr_resume(struct device *dev)
291 {
292 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
293 	int ret;
294 
295 	if (!device_may_wakeup(dev))
296 		return 0;
297 
298 	ret = disable_irq_wake(timer->irq);
299 
300 	brcmstb_waketmr_clear_alarm(timer);
301 
302 	return ret;
303 }
304 #endif /* CONFIG_PM_SLEEP */
305 
306 static SIMPLE_DEV_PM_OPS(brcmstb_waketmr_pm_ops,
307 			 brcmstb_waketmr_suspend, brcmstb_waketmr_resume);
308 
309 static const __maybe_unused struct of_device_id brcmstb_waketmr_of_match[] = {
310 	{ .compatible = "brcm,brcmstb-waketimer" },
311 	{ /* sentinel */ },
312 };
313 
314 static struct platform_driver brcmstb_waketmr_driver = {
315 	.probe			= brcmstb_waketmr_probe,
316 	.remove			= brcmstb_waketmr_remove,
317 	.driver = {
318 		.name		= "brcmstb-waketimer",
319 		.pm		= &brcmstb_waketmr_pm_ops,
320 		.of_match_table	= of_match_ptr(brcmstb_waketmr_of_match),
321 	}
322 };
323 module_platform_driver(brcmstb_waketmr_driver);
324 
325 MODULE_LICENSE("GPL v2");
326 MODULE_AUTHOR("Brian Norris");
327 MODULE_AUTHOR("Markus Mayer");
328 MODULE_DESCRIPTION("Wake-up timer driver for STB chips");
329