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 	writel_relaxed(secs + 1, timer->base + BRCMSTB_WKTMR_ALARM);
64 }
65 
66 static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
67 {
68 	struct brcmstb_waketmr *timer = data;
69 
70 	pm_wakeup_event(timer->dev, 0);
71 
72 	return IRQ_HANDLED;
73 }
74 
75 struct wktmr_time {
76 	u32 sec;
77 	u32 pre;
78 };
79 
80 static void wktmr_read(struct brcmstb_waketmr *timer,
81 		       struct wktmr_time *t)
82 {
83 	u32 tmp;
84 
85 	do {
86 		t->sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
87 		tmp = readl_relaxed(timer->base + BRCMSTB_WKTMR_PRESCALER_VAL);
88 	} while (tmp >= timer->rate);
89 
90 	t->pre = timer->rate - tmp;
91 }
92 
93 static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
94 {
95 	struct device *dev = timer->dev;
96 	int ret = 0;
97 
98 	if (device_may_wakeup(dev)) {
99 		ret = enable_irq_wake(timer->irq);
100 		if (ret) {
101 			dev_err(dev, "failed to enable wake-up interrupt\n");
102 			return ret;
103 		}
104 	}
105 
106 	return ret;
107 }
108 
109 /* If enabled as a wakeup-source, arm the timer when powering off */
110 static int brcmstb_waketmr_reboot(struct notifier_block *nb,
111 		unsigned long action, void *data)
112 {
113 	struct brcmstb_waketmr *timer;
114 
115 	timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);
116 
117 	/* Set timer for cold boot */
118 	if (action == SYS_POWER_OFF)
119 		brcmstb_waketmr_prepare_suspend(timer);
120 
121 	return NOTIFY_DONE;
122 }
123 
124 static int brcmstb_waketmr_gettime(struct device *dev,
125 				   struct rtc_time *tm)
126 {
127 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
128 	struct wktmr_time now;
129 
130 	wktmr_read(timer, &now);
131 
132 	rtc_time_to_tm(now.sec, tm);
133 
134 	return 0;
135 }
136 
137 static int brcmstb_waketmr_settime(struct device *dev,
138 				   struct rtc_time *tm)
139 {
140 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
141 	time64_t sec;
142 
143 	sec = rtc_tm_to_time64(tm);
144 
145 	if (sec > U32_MAX || sec < 0)
146 		return -EINVAL;
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 	if (sec > U32_MAX || sec < 0)
185 		return -EINVAL;
186 
187 	brcmstb_waketmr_set_alarm(timer, sec);
188 
189 	return 0;
190 }
191 
192 /*
193  * Does not do much but keep the RTC class happy. We always support
194  * alarms.
195  */
196 static int brcmstb_waketmr_alarm_enable(struct device *dev,
197 					unsigned int enabled)
198 {
199 	return 0;
200 }
201 
202 static const struct rtc_class_ops brcmstb_waketmr_ops = {
203 	.read_time	= brcmstb_waketmr_gettime,
204 	.set_time	= brcmstb_waketmr_settime,
205 	.read_alarm	= brcmstb_waketmr_getalarm,
206 	.set_alarm	= brcmstb_waketmr_setalarm,
207 	.alarm_irq_enable = brcmstb_waketmr_alarm_enable,
208 };
209 
210 static int brcmstb_waketmr_probe(struct platform_device *pdev)
211 {
212 	struct device *dev = &pdev->dev;
213 	struct brcmstb_waketmr *timer;
214 	struct resource *res;
215 	int ret;
216 
217 	timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
218 	if (!timer)
219 		return -ENOMEM;
220 
221 	platform_set_drvdata(pdev, timer);
222 	timer->dev = dev;
223 
224 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
225 	timer->base = devm_ioremap_resource(dev, res);
226 	if (IS_ERR(timer->base))
227 		return PTR_ERR(timer->base);
228 
229 	/*
230 	 * Set wakeup capability before requesting wakeup interrupt, so we can
231 	 * process boot-time "wakeups" (e.g., from S5 soft-off)
232 	 */
233 	device_set_wakeup_capable(dev, true);
234 	device_wakeup_enable(dev);
235 
236 	timer->irq = platform_get_irq(pdev, 0);
237 	if (timer->irq < 0)
238 		return -ENODEV;
239 
240 	timer->clk = devm_clk_get(dev, NULL);
241 	if (!IS_ERR(timer->clk)) {
242 		ret = clk_prepare_enable(timer->clk);
243 		if (ret)
244 			return ret;
245 		timer->rate = clk_get_rate(timer->clk);
246 		if (!timer->rate)
247 			timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
248 	} else {
249 		timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
250 		timer->clk = NULL;
251 	}
252 
253 	ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
254 			       "brcmstb-waketimer", timer);
255 	if (ret < 0)
256 		goto err_clk;
257 
258 	timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
259 	register_reboot_notifier(&timer->reboot_notifier);
260 
261 	timer->rtc = rtc_device_register("brcmstb-waketmr", dev,
262 					 &brcmstb_waketmr_ops, THIS_MODULE);
263 	if (IS_ERR(timer->rtc)) {
264 		dev_err(dev, "unable to register device\n");
265 		ret = PTR_ERR(timer->rtc);
266 		goto err_notifier;
267 	}
268 
269 	dev_info(dev, "registered, with irq %d\n", timer->irq);
270 
271 	return 0;
272 
273 err_notifier:
274 	unregister_reboot_notifier(&timer->reboot_notifier);
275 
276 err_clk:
277 	if (timer->clk)
278 		clk_disable_unprepare(timer->clk);
279 
280 	return ret;
281 }
282 
283 static int brcmstb_waketmr_remove(struct platform_device *pdev)
284 {
285 	struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);
286 
287 	unregister_reboot_notifier(&timer->reboot_notifier);
288 	rtc_device_unregister(timer->rtc);
289 
290 	return 0;
291 }
292 
293 #ifdef CONFIG_PM_SLEEP
294 static int brcmstb_waketmr_suspend(struct device *dev)
295 {
296 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
297 
298 	return brcmstb_waketmr_prepare_suspend(timer);
299 }
300 
301 static int brcmstb_waketmr_resume(struct device *dev)
302 {
303 	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
304 	int ret;
305 
306 	if (!device_may_wakeup(dev))
307 		return 0;
308 
309 	ret = disable_irq_wake(timer->irq);
310 
311 	brcmstb_waketmr_clear_alarm(timer);
312 
313 	return ret;
314 }
315 #endif /* CONFIG_PM_SLEEP */
316 
317 static SIMPLE_DEV_PM_OPS(brcmstb_waketmr_pm_ops,
318 			 brcmstb_waketmr_suspend, brcmstb_waketmr_resume);
319 
320 static const struct of_device_id brcmstb_waketmr_of_match[] = {
321 	{ .compatible = "brcm,brcmstb-waketimer" },
322 	{ /* sentinel */ },
323 };
324 
325 static struct platform_driver brcmstb_waketmr_driver = {
326 	.probe			= brcmstb_waketmr_probe,
327 	.remove			= brcmstb_waketmr_remove,
328 	.driver = {
329 		.name		= "brcmstb-waketimer",
330 		.pm		= &brcmstb_waketmr_pm_ops,
331 		.of_match_table	= of_match_ptr(brcmstb_waketmr_of_match),
332 	}
333 };
334 module_platform_driver(brcmstb_waketmr_driver);
335 
336 MODULE_LICENSE("GPL v2");
337 MODULE_AUTHOR("Brian Norris");
338 MODULE_AUTHOR("Markus Mayer");
339 MODULE_DESCRIPTION("Wake-up timer driver for STB chips");
340