rtc-cros-ec.c

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