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/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 /**
  18  * struct cros_ec_rtc - Driver data for EC RTC
  19  *
  20  * @cros_ec: Pointer to EC device
  21  * @rtc: Pointer to RTC device
  22  * @notifier: Notifier info for responding to EC events
  23  * @saved_alarm: Alarm to restore when interrupts are reenabled
  24  */
  25 struct cros_ec_rtc {
  26         struct cros_ec_device *cros_ec;
  27         struct rtc_device *rtc;
  28         struct notifier_block notifier;
  29         u32 saved_alarm;
  30 };
  31
  32 static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,
  33                            u32 *response)
  34 {
  35         int ret;
  36         struct {
  37                 struct cros_ec_command msg;
  38                 struct ec_response_rtc data;
  39         } __packed msg;
  40
  41         memset(&msg, 0, sizeof(msg));
  42         msg.msg.command = command;
  43         msg.msg.insize = sizeof(msg.data);
  44
  45         ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
  46         if (ret < 0) {
  47                 dev_err(cros_ec->dev,
  48                         "error getting %s from EC: %d\n",
  49                         command == EC_CMD_RTC_GET_VALUE ? "time" : "alarm",
  50                         ret);
  51                 return ret;
  52         }
  53
  54         *response = msg.data.time;
  55
  56         return 0;
  57 }
  58
  59 static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,
  60                            u32 param)
  61 {
  62         int ret = 0;
  63         struct {
  64                 struct cros_ec_command msg;
  65                 struct ec_response_rtc data;
  66         } __packed msg;
  67
  68         memset(&msg, 0, sizeof(msg));
  69         msg.msg.command = command;
  70         msg.msg.outsize = sizeof(msg.data);
  71         msg.data.time = param;
  72
  73         ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
  74         if (ret < 0) {
  75                 dev_err(cros_ec->dev, "error setting %s on EC: %d\n",
  76                         command == EC_CMD_RTC_SET_VALUE ? "time" : "alarm",
  77                         ret);
  78                 return ret;
  79         }
  80
  81         return 0;
  82 }
  83
  84 /* Read the current time from the EC. */
  85 static int cros_ec_rtc_read_time(struct device *dev, struct rtc_time *tm)
  86 {
  87         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
  88         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
  89         int ret;
  90         u32 time;
  91
  92         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &time);
  93         if (ret) {
  94                 dev_err(dev, "error getting time: %d\n", ret);
  95                 return ret;
  96         }
  97
  98         rtc_time64_to_tm(time, tm);
  99
 100         return 0;
 101 }
 102
 103 /* Set the current EC time. */
 104 static int cros_ec_rtc_set_time(struct device *dev, struct rtc_time *tm)
 105 {
 106         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 107         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 108         int ret;
 109         time64_t time = rtc_tm_to_time64(tm);
 110
 111         ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_VALUE, (u32)time);
 112         if (ret < 0) {
 113                 dev_err(dev, "error setting time: %d\n", ret);
 114                 return ret;
 115         }
 116
 117         return 0;
 118 }
 119
 120 /* Read alarm time from RTC. */
 121 static int cros_ec_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 122 {
 123         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 124         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 125         int ret;
 126         u32 current_time, alarm_offset;
 127
 128         /*
 129          * The EC host command for getting the alarm is relative (i.e. 5
 130          * seconds from now) whereas rtc_wkalrm is absolute. Get the current
 131          * RTC time first so we can calculate the relative time.
 132          */
 133         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 134         if (ret < 0) {
 135                 dev_err(dev, "error getting time: %d\n", ret);
 136                 return ret;
 137         }
 138
 139         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM, &alarm_offset);
 140         if (ret < 0) {
 141                 dev_err(dev, "error getting alarm: %d\n", ret);
 142                 return ret;
 143         }
 144
 145         rtc_time64_to_tm(current_time + alarm_offset, &alrm->time);
 146
 147         return 0;
 148 }
 149
 150 /* Set the EC's RTC alarm. */
 151 static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 152 {
 153         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 154         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 155         int ret;
 156         time64_t alarm_time;
 157         u32 current_time, alarm_offset;
 158
 159         /*
 160          * The EC host command for setting the alarm is relative
 161          * (i.e. 5 seconds from now) whereas rtc_wkalrm is absolute.
 162          * Get the current RTC time first so we can calculate the
 163          * relative time.
 164          */
 165         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 166         if (ret < 0) {
 167                 dev_err(dev, "error getting time: %d\n", ret);
 168                 return ret;
 169         }
 170
 171         alarm_time = rtc_tm_to_time64(&alrm->time);
 172
 173         if (alarm_time < 0 || alarm_time > U32_MAX)
 174                 return -EINVAL;
 175
 176         if (!alrm->enabled) {
 177                 /*
 178                  * If the alarm is being disabled, send an alarm
 179                  * clear command.
 180                  */
 181                 alarm_offset = EC_RTC_ALARM_CLEAR;
 182                 cros_ec_rtc->saved_alarm = (u32)alarm_time;
 183         } else {
 184                 /* Don't set an alarm in the past. */
 185                 if ((u32)alarm_time <= current_time)
 186                         return -ETIME;
 187
 188                 alarm_offset = (u32)alarm_time - current_time;
 189         }
 190
 191         ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
 192         if (ret < 0) {
 193                 dev_err(dev, "error setting alarm: %d\n", ret);
 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         ret = rtc_register_device(cros_ec_rtc->rtc);
 354         if (ret)
 355                 return ret;
 356
 357         /* Get RTC events from the EC. */
 358         cros_ec_rtc->notifier.notifier_call = cros_ec_rtc_event;
 359         ret = blocking_notifier_chain_register(&cros_ec->event_notifier,
 360                                                &cros_ec_rtc->notifier);
 361         if (ret) {
 362                 dev_err(&pdev->dev, "failed to register notifier\n");
 363                 return ret;
 364         }
 365
 366         return 0;
 367 }
 368
 369 static int cros_ec_rtc_remove(struct platform_device *pdev)
 370 {
 371         struct cros_ec_rtc *cros_ec_rtc = platform_get_drvdata(pdev);
 372         struct device *dev = &pdev->dev;
 373         int ret;
 374
 375         ret = blocking_notifier_chain_unregister(
 376                                 &cros_ec_rtc->cros_ec->event_notifier,
 377                                 &cros_ec_rtc->notifier);
 378         if (ret) {
 379                 dev_err(dev, "failed to unregister notifier\n");
 380                 return ret;
 381         }
 382
 383         return 0;
 384 }
 385
 386 static struct platform_driver cros_ec_rtc_driver = {
 387         .probe = cros_ec_rtc_probe,
 388         .remove = cros_ec_rtc_remove,
 389         .driver = {
 390                 .name = DRV_NAME,
 391                 .pm = &cros_ec_rtc_pm_ops,
 392         },
 393 };
 394
 395 module_platform_driver(cros_ec_rtc_driver);
 396
 397 MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
 398 MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
 399 MODULE_LICENSE("GPL v2");
 400 MODULE_ALIAS("platform:" DRV_NAME);