drivers/rtc/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  */
  28 struct 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
  35 static 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
  57 static 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. */
  78 static 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. */
  97 static 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. */
 114 static 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, &current_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. */
 144 static 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, &current_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
 200 static 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, &current_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
 260 static 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
 282 static 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
 291 static 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
 302 static 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
 314 static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,
 315                          cros_ec_rtc_resume);
 316
 317 static 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
 383 static 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
 396 static const struct platform_device_id cros_ec_rtc_id[] = {
 397         { DRV_NAME, 0 },
 398         {}
 399 };
 400 MODULE_DEVICE_TABLE(platform, cros_ec_rtc_id);
 401
 402 static 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
 412 module_platform_driver(cros_ec_rtc_driver);
 413
 414 MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
 415 MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
 416 MODULE_LICENSE("GPL v2");