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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 int ret;
39 struct {
40 struct cros_ec_command msg;
41 struct ec_response_rtc data;
42 } __packed msg;
43
44 memset(&msg, 0, sizeof(msg));
45 msg.msg.command = command;
46 msg.msg.insize = sizeof(msg.data);
47
48 ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
49 if (ret < 0)
50 return ret;
51
52 *response = msg.data.time;
53
54 return 0;
55}
56
57static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,
58 u32 param)
59{
60 int ret;
61 struct {
62 struct cros_ec_command msg;
63 struct ec_response_rtc data;
64 } __packed msg;
65
66 memset(&msg, 0, sizeof(msg));
67 msg.msg.command = command;
68 msg.msg.outsize = sizeof(msg.data);
69 msg.data.time = param;
70
71 ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
72 if (ret < 0)
73 return ret;
74 return 0;
75}
76
77/* Read the current time from the EC. */
78static int cros_ec_rtc_read_time(struct device *dev, struct rtc_time *tm)
79{
80 struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
81 struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
82 int ret;
83 u32 time;
84
85 ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &time);
86 if (ret) {
87 dev_err(dev, "error getting time: %d\n", ret);
88 return ret;
89 }
90
91 rtc_time64_to_tm(time, tm);
92
93 return 0;
94}
95
96/* Set the current EC time. */
97static int cros_ec_rtc_set_time(struct device *dev, struct rtc_time *tm)
98{
99 struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
100 struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
101 int ret;
102 time64_t time = rtc_tm_to_time64(tm);
103
104 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_VALUE, (u32)time);
105 if (ret < 0) {
106 dev_err(dev, "error setting time: %d\n", ret);
107 return ret;
108 }
109
110 return 0;
111}
112
113/* Read alarm time from RTC. */
114static int cros_ec_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
115{
116 struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
117 struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
118 int ret;
119 u32 current_time, alarm_offset;
120
121 /*
122 * The EC host command for getting the alarm is relative (i.e. 5
123 * seconds from now) whereas rtc_wkalrm is absolute. Get the current
124 * RTC time first so we can calculate the relative time.
125 */
126 ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, ¤t_time);
127 if (ret < 0) {
128 dev_err(dev, "error getting time: %d\n", ret);
129 return ret;
130 }
131
132 ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM, &alarm_offset);
133 if (ret < 0) {
134 dev_err(dev, "error getting alarm: %d\n", ret);
135 return ret;
136 }
137
138 rtc_time64_to_tm(current_time + alarm_offset, &alrm->time);
139
140 return 0;
141}
142
143/* Set the EC's RTC alarm. */
144static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
145{
146 struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
147 struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
148 int ret;
149 time64_t alarm_time;
150 u32 current_time, alarm_offset;
151
152 /*
153 * The EC host command for setting the alarm is relative
154 * (i.e. 5 seconds from now) whereas rtc_wkalrm is absolute.
155 * Get the current RTC time first so we can calculate the
156 * relative time.
157 */
158 ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, ¤t_time);
159 if (ret < 0) {
160 dev_err(dev, "error getting time: %d\n", ret);
161 return ret;
162 }
163
164 alarm_time = rtc_tm_to_time64(&alrm->time);
165
166 if (alarm_time < 0 || alarm_time > U32_MAX)
167 return -EINVAL;
168
169 if (!alrm->enabled) {
170 /*
171 * If the alarm is being disabled, send an alarm
172 * clear command.
173 */
174 alarm_offset = EC_RTC_ALARM_CLEAR;
175 cros_ec_rtc->saved_alarm = (u32)alarm_time;
176 } else {
177 /* Don't set an alarm in the past. */
178 if ((u32)alarm_time <= current_time)
179 return -ETIME;
180
181 alarm_offset = (u32)alarm_time - current_time;
182 }
183
184 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
185 if (ret < 0) {
186 dev_err(dev, "error setting alarm in %u seconds: %d\n",
187 alarm_offset, ret);
188 /*
189 * The EC code returns -EINVAL if the alarm time is too
190 * far in the future. Convert it to the expected error code.
191 */
192 if (ret == -EINVAL)
193 ret = -ERANGE;
194 return ret;
195 }
196
197 return 0;
198}
199
200static int cros_ec_rtc_alarm_irq_enable(struct device *dev,
201 unsigned int enabled)
202{
203 struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
204 struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
205 int ret;
206 u32 current_time, alarm_offset, alarm_value;
207
208 ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, ¤t_time);
209 if (ret < 0) {
210 dev_err(dev, "error getting time: %d\n", ret);
211 return ret;
212 }
213
214 if (enabled) {
215 /* Restore saved alarm if it's still in the future. */
216 if (cros_ec_rtc->saved_alarm < current_time)
217 alarm_offset = EC_RTC_ALARM_CLEAR;
218 else
219 alarm_offset = cros_ec_rtc->saved_alarm - current_time;
220
221 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
222 alarm_offset);
223 if (ret < 0) {
224 dev_err(dev, "error restoring alarm: %d\n", ret);
225 return ret;
226 }
227 } else {
228 /* Disable alarm, saving the old alarm value. */
229 ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM,
230 &alarm_offset);
231 if (ret < 0) {
232 dev_err(dev, "error saving alarm: %d\n", ret);
233 return ret;
234 }
235
236 alarm_value = current_time + alarm_offset;
237
238 /*
239 * If the current EC alarm is already past, we don't want
240 * to set an alarm when we go through the alarm irq enable
241 * path.
242 */
243 if (alarm_value < current_time)
244 cros_ec_rtc->saved_alarm = EC_RTC_ALARM_CLEAR;
245 else
246 cros_ec_rtc->saved_alarm = alarm_value;
247
248 alarm_offset = EC_RTC_ALARM_CLEAR;
249 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
250 alarm_offset);
251 if (ret < 0) {
252 dev_err(dev, "error disabling alarm: %d\n", ret);
253 return ret;
254 }
255 }
256
257 return 0;
258}
259
260static int cros_ec_rtc_event(struct notifier_block *nb,
261 unsigned long queued_during_suspend,
262 void *_notify)
263{
264 struct cros_ec_rtc *cros_ec_rtc;
265 struct rtc_device *rtc;
266 struct cros_ec_device *cros_ec;
267 u32 host_event;
268
269 cros_ec_rtc = container_of(nb, struct cros_ec_rtc, notifier);
270 rtc = cros_ec_rtc->rtc;
271 cros_ec = cros_ec_rtc->cros_ec;
272
273 host_event = cros_ec_get_host_event(cros_ec);
274 if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_RTC)) {
275 rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
276 return NOTIFY_OK;
277 } else {
278 return NOTIFY_DONE;
279 }
280}
281
282static const struct rtc_class_ops cros_ec_rtc_ops = {
283 .read_time = cros_ec_rtc_read_time,
284 .set_time = cros_ec_rtc_set_time,
285 .read_alarm = cros_ec_rtc_read_alarm,
286 .set_alarm = cros_ec_rtc_set_alarm,
287 .alarm_irq_enable = cros_ec_rtc_alarm_irq_enable,
288};
289
290#ifdef CONFIG_PM_SLEEP
291static int cros_ec_rtc_suspend(struct device *dev)
292{
293 struct platform_device *pdev = to_platform_device(dev);
294 struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
295
296 if (device_may_wakeup(dev))
297 return enable_irq_wake(cros_ec_rtc->cros_ec->irq);
298
299 return 0;
300}
301
302static int cros_ec_rtc_resume(struct device *dev)
303{
304 struct platform_device *pdev = to_platform_device(dev);
305 struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
306
307 if (device_may_wakeup(dev))
308 return disable_irq_wake(cros_ec_rtc->cros_ec->irq);
309
310 return 0;
311}
312#endif
313
314static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,
315 cros_ec_rtc_resume);
316
317static int cros_ec_rtc_probe(struct platform_device *pdev)
318{
319 struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
320 struct cros_ec_device *cros_ec = ec_dev->ec_dev;
321 struct cros_ec_rtc *cros_ec_rtc;
322 struct rtc_time tm;
323 int ret;
324
325 cros_ec_rtc = devm_kzalloc(&pdev->dev, sizeof(*cros_ec_rtc),
326 GFP_KERNEL);
327 if (!cros_ec_rtc)
328 return -ENOMEM;
329
330 platform_set_drvdata(pdev, cros_ec_rtc);
331 cros_ec_rtc->cros_ec = cros_ec;
332
333 /* Get initial time */
334 ret = cros_ec_rtc_read_time(&pdev->dev, &tm);
335 if (ret) {
336 dev_err(&pdev->dev, "failed to read RTC time\n");
337 return ret;
338 }
339
340 ret = device_init_wakeup(&pdev->dev, 1);
341 if (ret) {
342 dev_err(&pdev->dev, "failed to initialize wakeup\n");
343 return ret;
344 }
345
346 cros_ec_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
347 if (IS_ERR(cros_ec_rtc->rtc))
348 return PTR_ERR(cros_ec_rtc->rtc);
349
350 cros_ec_rtc->rtc->ops = &cros_ec_rtc_ops;
351 cros_ec_rtc->rtc->range_max = U32_MAX;
352
353 /*
354 * The RTC on some older Chromebooks can only handle alarms less than
355 * 24 hours in the future. The only way to find out is to try to set an
356 * alarm further in the future. If that fails, assume that the RTC
357 * connected to the EC can only handle less than 24 hours of alarm
358 * window.
359 */
360 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, SECS_PER_DAY * 2);
361 if (ret == -EINVAL)
362 cros_ec_rtc->rtc->alarm_offset_max = SECS_PER_DAY - 1;
363
364 (void)cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
365 EC_RTC_ALARM_CLEAR);
366
367 ret = devm_rtc_register_device(cros_ec_rtc->rtc);
368 if (ret)
369 return ret;
370
371 /* Get RTC events from the EC. */
372 cros_ec_rtc->notifier.notifier_call = cros_ec_rtc_event;
373 ret = blocking_notifier_chain_register(&cros_ec->event_notifier,
374 &cros_ec_rtc->notifier);
375 if (ret) {
376 dev_err(&pdev->dev, "failed to register notifier\n");
377 return ret;
378 }
379
380 return 0;
381}
382
383static void cros_ec_rtc_remove(struct platform_device *pdev)
384{
385 struct cros_ec_rtc *cros_ec_rtc = platform_get_drvdata(pdev);
386 struct device *dev = &pdev->dev;
387 int ret;
388
389 ret = blocking_notifier_chain_unregister(
390 &cros_ec_rtc->cros_ec->event_notifier,
391 &cros_ec_rtc->notifier);
392 if (ret)
393 dev_err(dev, "failed to unregister notifier\n");
394}
395
396static const struct platform_device_id cros_ec_rtc_id[] = {
397 { DRV_NAME, 0 },
398 {}
399};
400MODULE_DEVICE_TABLE(platform, cros_ec_rtc_id);
401
402static struct platform_driver cros_ec_rtc_driver = {
403 .probe = cros_ec_rtc_probe,
404 .remove = cros_ec_rtc_remove,
405 .driver = {
406 .name = DRV_NAME,
407 .pm = &cros_ec_rtc_pm_ops,
408 },
409 .id_table = cros_ec_rtc_id,
410};
411
412module_platform_driver(cros_ec_rtc_driver);
413
414MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
415MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
416MODULE_LICENSE("GPL v2");