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, ¤t_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, ¤t_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, ¤t_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
