xref: /openbmc/linux/drivers/rtc/rtc-cros-ec.c (revision 00c3092d)
1 // SPDX-License-Identifier: GPL-2.0
2 // RTC driver for ChromeOS Embedded Controller.
3 //
4 // Copyright (C) 2017 Google, Inc.
5 // Author: Stephen Barber <smbarber@chromium.org>
6 
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/platform_data/cros_ec_commands.h>
10 #include <linux/platform_data/cros_ec_proto.h>
11 #include <linux/platform_device.h>
12 #include <linux/rtc.h>
13 #include <linux/slab.h>
14 
15 #define DRV_NAME	"cros-ec-rtc"
16 
17 #define SECS_PER_DAY	(24 * 60 * 60)
18 
19 /**
20  * struct cros_ec_rtc - Driver data for EC RTC
21  *
22  * @cros_ec: Pointer to EC device
23  * @rtc: Pointer to RTC device
24  * @notifier: Notifier info for responding to EC events
25  * @saved_alarm: Alarm to restore when interrupts are reenabled
26  */
27 struct cros_ec_rtc {
28 	struct cros_ec_device *cros_ec;
29 	struct rtc_device *rtc;
30 	struct notifier_block notifier;
31 	u32 saved_alarm;
32 };
33 
cros_ec_rtc_get(struct cros_ec_device * cros_ec,u32 command,u32 * response)34 static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,
35 			   u32 *response)
36 {
37 	int ret;
38 	struct {
39 		struct cros_ec_command msg;
40 		struct ec_response_rtc data;
41 	} __packed msg;
42 
43 	memset(&msg, 0, sizeof(msg));
44 	msg.msg.command = command;
45 	msg.msg.insize = sizeof(msg.data);
46 
47 	ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
48 	if (ret < 0)
49 		return ret;
50 
51 	*response = msg.data.time;
52 
53 	return 0;
54 }
55 
cros_ec_rtc_set(struct cros_ec_device * cros_ec,u32 command,u32 param)56 static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,
57 			   u32 param)
58 {
59 	int ret;
60 	struct {
61 		struct cros_ec_command msg;
62 		struct ec_response_rtc data;
63 	} __packed msg;
64 
65 	memset(&msg, 0, sizeof(msg));
66 	msg.msg.command = command;
67 	msg.msg.outsize = sizeof(msg.data);
68 	msg.data.time = param;
69 
70 	ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
71 	if (ret < 0)
72 		return ret;
73 	return 0;
74 }
75 
76 /* Read the current time from the EC. */
cros_ec_rtc_read_time(struct device * dev,struct rtc_time * tm)77 static int cros_ec_rtc_read_time(struct device *dev, struct rtc_time *tm)
78 {
79 	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
80 	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
81 	int ret;
82 	u32 time;
83 
84 	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &time);
85 	if (ret) {
86 		dev_err(dev, "error getting time: %d\n", ret);
87 		return ret;
88 	}
89 
90 	rtc_time64_to_tm(time, tm);
91 
92 	return 0;
93 }
94 
95 /* Set the current EC time. */
cros_ec_rtc_set_time(struct device * dev,struct rtc_time * tm)96 static int cros_ec_rtc_set_time(struct device *dev, struct rtc_time *tm)
97 {
98 	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
99 	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
100 	int ret;
101 	time64_t time = rtc_tm_to_time64(tm);
102 
103 	ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_VALUE, (u32)time);
104 	if (ret < 0) {
105 		dev_err(dev, "error setting time: %d\n", ret);
106 		return ret;
107 	}
108 
109 	return 0;
110 }
111 
112 /* Read alarm time from RTC. */
cros_ec_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)113 static int cros_ec_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
114 {
115 	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
116 	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
117 	int ret;
118 	u32 current_time, alarm_offset;
119 
120 	/*
121 	 * The EC host command for getting the alarm is relative (i.e. 5
122 	 * seconds from now) whereas rtc_wkalrm is absolute. Get the current
123 	 * RTC time first so we can calculate the relative time.
124 	 */
125 	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
126 	if (ret < 0) {
127 		dev_err(dev, "error getting time: %d\n", ret);
128 		return ret;
129 	}
130 
131 	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM, &alarm_offset);
132 	if (ret < 0) {
133 		dev_err(dev, "error getting alarm: %d\n", ret);
134 		return ret;
135 	}
136 
137 	rtc_time64_to_tm(current_time + alarm_offset, &alrm->time);
138 
139 	return 0;
140 }
141 
142 /* Set the EC's RTC alarm. */
cros_ec_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)143 static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
144 {
145 	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
146 	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
147 	int ret;
148 	time64_t alarm_time;
149 	u32 current_time, alarm_offset;
150 
151 	/*
152 	 * The EC host command for setting the alarm is relative
153 	 * (i.e. 5 seconds from now) whereas rtc_wkalrm is absolute.
154 	 * Get the current RTC time first so we can calculate the
155 	 * relative time.
156 	 */
157 	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
158 	if (ret < 0) {
159 		dev_err(dev, "error getting time: %d\n", ret);
160 		return ret;
161 	}
162 
163 	alarm_time = rtc_tm_to_time64(&alrm->time);
164 
165 	if (alarm_time < 0 || alarm_time > U32_MAX)
166 		return -EINVAL;
167 
168 	if (!alrm->enabled) {
169 		/*
170 		 * If the alarm is being disabled, send an alarm
171 		 * clear command.
172 		 */
173 		alarm_offset = EC_RTC_ALARM_CLEAR;
174 		cros_ec_rtc->saved_alarm = (u32)alarm_time;
175 	} else {
176 		/* Don't set an alarm in the past. */
177 		if ((u32)alarm_time <= current_time)
178 			return -ETIME;
179 
180 		alarm_offset = (u32)alarm_time - current_time;
181 	}
182 
183 	ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
184 	if (ret < 0) {
185 		dev_err(dev, "error setting alarm in %u seconds: %d\n",
186 			alarm_offset, ret);
187 		/*
188 		 * The EC code returns -EINVAL if the alarm time is too
189 		 * far in the future. Convert it to the expected error code.
190 		 */
191 		if (ret == -EINVAL)
192 			ret = -ERANGE;
193 		return ret;
194 	}
195 
196 	return 0;
197 }
198 
cros_ec_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)199 static int cros_ec_rtc_alarm_irq_enable(struct device *dev,
200 					unsigned int enabled)
201 {
202 	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
203 	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
204 	int ret;
205 	u32 current_time, alarm_offset, alarm_value;
206 
207 	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
208 	if (ret < 0) {
209 		dev_err(dev, "error getting time: %d\n", ret);
210 		return ret;
211 	}
212 
213 	if (enabled) {
214 		/* Restore saved alarm if it's still in the future. */
215 		if (cros_ec_rtc->saved_alarm < current_time)
216 			alarm_offset = EC_RTC_ALARM_CLEAR;
217 		else
218 			alarm_offset = cros_ec_rtc->saved_alarm - current_time;
219 
220 		ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
221 				      alarm_offset);
222 		if (ret < 0) {
223 			dev_err(dev, "error restoring alarm: %d\n", ret);
224 			return ret;
225 		}
226 	} else {
227 		/* Disable alarm, saving the old alarm value. */
228 		ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM,
229 				      &alarm_offset);
230 		if (ret < 0) {
231 			dev_err(dev, "error saving alarm: %d\n", ret);
232 			return ret;
233 		}
234 
235 		alarm_value = current_time + alarm_offset;
236 
237 		/*
238 		 * If the current EC alarm is already past, we don't want
239 		 * to set an alarm when we go through the alarm irq enable
240 		 * path.
241 		 */
242 		if (alarm_value < current_time)
243 			cros_ec_rtc->saved_alarm = EC_RTC_ALARM_CLEAR;
244 		else
245 			cros_ec_rtc->saved_alarm = alarm_value;
246 
247 		alarm_offset = EC_RTC_ALARM_CLEAR;
248 		ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
249 				      alarm_offset);
250 		if (ret < 0) {
251 			dev_err(dev, "error disabling alarm: %d\n", ret);
252 			return ret;
253 		}
254 	}
255 
256 	return 0;
257 }
258 
cros_ec_rtc_event(struct notifier_block * nb,unsigned long queued_during_suspend,void * _notify)259 static int cros_ec_rtc_event(struct notifier_block *nb,
260 			     unsigned long queued_during_suspend,
261 			     void *_notify)
262 {
263 	struct cros_ec_rtc *cros_ec_rtc;
264 	struct rtc_device *rtc;
265 	struct cros_ec_device *cros_ec;
266 	u32 host_event;
267 
268 	cros_ec_rtc = container_of(nb, struct cros_ec_rtc, notifier);
269 	rtc = cros_ec_rtc->rtc;
270 	cros_ec = cros_ec_rtc->cros_ec;
271 
272 	host_event = cros_ec_get_host_event(cros_ec);
273 	if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_RTC)) {
274 		rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
275 		return NOTIFY_OK;
276 	} else {
277 		return NOTIFY_DONE;
278 	}
279 }
280 
281 static const struct rtc_class_ops cros_ec_rtc_ops = {
282 	.read_time = cros_ec_rtc_read_time,
283 	.set_time = cros_ec_rtc_set_time,
284 	.read_alarm = cros_ec_rtc_read_alarm,
285 	.set_alarm = cros_ec_rtc_set_alarm,
286 	.alarm_irq_enable = cros_ec_rtc_alarm_irq_enable,
287 };
288 
289 #ifdef CONFIG_PM_SLEEP
cros_ec_rtc_suspend(struct device * dev)290 static int cros_ec_rtc_suspend(struct device *dev)
291 {
292 	struct platform_device *pdev = to_platform_device(dev);
293 	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
294 
295 	if (device_may_wakeup(dev))
296 		return enable_irq_wake(cros_ec_rtc->cros_ec->irq);
297 
298 	return 0;
299 }
300 
cros_ec_rtc_resume(struct device * dev)301 static int cros_ec_rtc_resume(struct device *dev)
302 {
303 	struct platform_device *pdev = to_platform_device(dev);
304 	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
305 
306 	if (device_may_wakeup(dev))
307 		return disable_irq_wake(cros_ec_rtc->cros_ec->irq);
308 
309 	return 0;
310 }
311 #endif
312 
313 static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,
314 			 cros_ec_rtc_resume);
315 
cros_ec_rtc_probe(struct platform_device * pdev)316 static int cros_ec_rtc_probe(struct platform_device *pdev)
317 {
318 	struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
319 	struct cros_ec_device *cros_ec = ec_dev->ec_dev;
320 	struct cros_ec_rtc *cros_ec_rtc;
321 	struct rtc_time tm;
322 	int ret;
323 
324 	cros_ec_rtc = devm_kzalloc(&pdev->dev, sizeof(*cros_ec_rtc),
325 				   GFP_KERNEL);
326 	if (!cros_ec_rtc)
327 		return -ENOMEM;
328 
329 	platform_set_drvdata(pdev, cros_ec_rtc);
330 	cros_ec_rtc->cros_ec = cros_ec;
331 
332 	/* Get initial time */
333 	ret = cros_ec_rtc_read_time(&pdev->dev, &tm);
334 	if (ret) {
335 		dev_err(&pdev->dev, "failed to read RTC time\n");
336 		return ret;
337 	}
338 
339 	ret = device_init_wakeup(&pdev->dev, 1);
340 	if (ret) {
341 		dev_err(&pdev->dev, "failed to initialize wakeup\n");
342 		return ret;
343 	}
344 
345 	cros_ec_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
346 	if (IS_ERR(cros_ec_rtc->rtc))
347 		return PTR_ERR(cros_ec_rtc->rtc);
348 
349 	cros_ec_rtc->rtc->ops = &cros_ec_rtc_ops;
350 	cros_ec_rtc->rtc->range_max = U32_MAX;
351 
352 	/*
353 	 * The RTC on some older Chromebooks can only handle alarms less than
354 	 * 24 hours in the future. The only way to find out is to try to set an
355 	 * alarm further in the future. If that fails, assume that the RTC
356 	 * connected to the EC can only handle less than 24 hours of alarm
357 	 * window.
358 	 */
359 	ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, SECS_PER_DAY * 2);
360 	if (ret == -EINVAL)
361 		cros_ec_rtc->rtc->alarm_offset_max = SECS_PER_DAY - 1;
362 
363 	(void)cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
364 			      EC_RTC_ALARM_CLEAR);
365 
366 	ret = devm_rtc_register_device(cros_ec_rtc->rtc);
367 	if (ret)
368 		return ret;
369 
370 	/* Get RTC events from the EC. */
371 	cros_ec_rtc->notifier.notifier_call = cros_ec_rtc_event;
372 	ret = blocking_notifier_chain_register(&cros_ec->event_notifier,
373 					       &cros_ec_rtc->notifier);
374 	if (ret) {
375 		dev_err(&pdev->dev, "failed to register notifier\n");
376 		return ret;
377 	}
378 
379 	return 0;
380 }
381 
cros_ec_rtc_remove(struct platform_device * pdev)382 static void cros_ec_rtc_remove(struct platform_device *pdev)
383 {
384 	struct cros_ec_rtc *cros_ec_rtc = platform_get_drvdata(pdev);
385 	struct device *dev = &pdev->dev;
386 	int ret;
387 
388 	ret = blocking_notifier_chain_unregister(
389 				&cros_ec_rtc->cros_ec->event_notifier,
390 				&cros_ec_rtc->notifier);
391 	if (ret)
392 		dev_err(dev, "failed to unregister notifier\n");
393 }
394 
395 static struct platform_driver cros_ec_rtc_driver = {
396 	.probe = cros_ec_rtc_probe,
397 	.remove_new = cros_ec_rtc_remove,
398 	.driver = {
399 		.name = DRV_NAME,
400 		.pm = &cros_ec_rtc_pm_ops,
401 	},
402 };
403 
404 module_platform_driver(cros_ec_rtc_driver);
405 
406 MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
407 MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
408 MODULE_LICENSE("GPL v2");
409 MODULE_ALIAS("platform:" DRV_NAME);
410