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/mfd/cros_ec.h>
   9 #include <linux/mfd/cros_ec_commands.h>
  10 #include <linux/module.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;
 110
 111         time = rtc_tm_to_time64(tm);
 112         if (time < 0 || time > U32_MAX)
 113                 return -EINVAL;
 114
 115         ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_VALUE, (u32)time);
 116         if (ret < 0) {
 117                 dev_err(dev, "error setting time: %d\n", ret);
 118                 return ret;
 119         }
 120
 121         return 0;
 122 }
 123
 124 /* Read alarm time from RTC. */
 125 static int cros_ec_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 126 {
 127         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 128         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 129         int ret;
 130         u32 current_time, alarm_offset;
 131
 132         /*
 133          * The EC host command for getting the alarm is relative (i.e. 5
 134          * seconds from now) whereas rtc_wkalrm is absolute. Get the current
 135          * RTC time first so we can calculate the relative time.
 136          */
 137         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 138         if (ret < 0) {
 139                 dev_err(dev, "error getting time: %d\n", ret);
 140                 return ret;
 141         }
 142
 143         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM, &alarm_offset);
 144         if (ret < 0) {
 145                 dev_err(dev, "error getting alarm: %d\n", ret);
 146                 return ret;
 147         }
 148
 149         rtc_time64_to_tm(current_time + alarm_offset, &alrm->time);
 150
 151         return 0;
 152 }
 153
 154 /* Set the EC's RTC alarm. */
 155 static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 156 {
 157         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 158         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 159         int ret;
 160         time64_t alarm_time;
 161         u32 current_time, alarm_offset;
 162
 163         /*
 164          * The EC host command for setting the alarm is relative
 165          * (i.e. 5 seconds from now) whereas rtc_wkalrm is absolute.
 166          * Get the current RTC time first so we can calculate the
 167          * relative time.
 168          */
 169         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 170         if (ret < 0) {
 171                 dev_err(dev, "error getting time: %d\n", ret);
 172                 return ret;
 173         }
 174
 175         alarm_time = rtc_tm_to_time64(&alrm->time);
 176
 177         if (alarm_time < 0 || alarm_time > U32_MAX)
 178                 return -EINVAL;
 179
 180         if (!alrm->enabled) {
 181                 /*
 182                  * If the alarm is being disabled, send an alarm
 183                  * clear command.
 184                  */
 185                 alarm_offset = EC_RTC_ALARM_CLEAR;
 186                 cros_ec_rtc->saved_alarm = (u32)alarm_time;
 187         } else {
 188                 /* Don't set an alarm in the past. */
 189                 if ((u32)alarm_time <= current_time)
 190                         return -ETIME;
 191
 192                 alarm_offset = (u32)alarm_time - current_time;
 193         }
 194
 195         ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
 196         if (ret < 0) {
 197                 dev_err(dev, "error setting alarm: %d\n", ret);
 198                 return ret;
 199         }
 200
 201         return 0;
 202 }
 203
 204 static int cros_ec_rtc_alarm_irq_enable(struct device *dev,
 205                                         unsigned int enabled)
 206 {
 207         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 208         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 209         int ret;
 210         u32 current_time, alarm_offset, alarm_value;
 211
 212         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 213         if (ret < 0) {
 214                 dev_err(dev, "error getting time: %d\n", ret);
 215                 return ret;
 216         }
 217
 218         if (enabled) {
 219                 /* Restore saved alarm if it's still in the future. */
 220                 if (cros_ec_rtc->saved_alarm < current_time)
 221                         alarm_offset = EC_RTC_ALARM_CLEAR;
 222                 else
 223                         alarm_offset = cros_ec_rtc->saved_alarm - current_time;
 224
 225                 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
 226                                       alarm_offset);
 227                 if (ret < 0) {
 228                         dev_err(dev, "error restoring alarm: %d\n", ret);
 229                         return ret;
 230                 }
 231         } else {
 232                 /* Disable alarm, saving the old alarm value. */
 233                 ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM,
 234                                       &alarm_offset);
 235                 if (ret < 0) {
 236                         dev_err(dev, "error saving alarm: %d\n", ret);
 237                         return ret;
 238                 }
 239
 240                 alarm_value = current_time + alarm_offset;
 241
 242                 /*
 243                  * If the current EC alarm is already past, we don't want
 244                  * to set an alarm when we go through the alarm irq enable
 245                  * path.
 246                  */
 247                 if (alarm_value < current_time)
 248                         cros_ec_rtc->saved_alarm = EC_RTC_ALARM_CLEAR;
 249                 else
 250                         cros_ec_rtc->saved_alarm = alarm_value;
 251
 252                 alarm_offset = EC_RTC_ALARM_CLEAR;
 253                 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
 254                                       alarm_offset);
 255                 if (ret < 0) {
 256                         dev_err(dev, "error disabling alarm: %d\n", ret);
 257                         return ret;
 258                 }
 259         }
 260
 261         return 0;
 262 }
 263
 264 static int cros_ec_rtc_event(struct notifier_block *nb,
 265                              unsigned long queued_during_suspend,
 266                              void *_notify)
 267 {
 268         struct cros_ec_rtc *cros_ec_rtc;
 269         struct rtc_device *rtc;
 270         struct cros_ec_device *cros_ec;
 271         u32 host_event;
 272
 273         cros_ec_rtc = container_of(nb, struct cros_ec_rtc, notifier);
 274         rtc = cros_ec_rtc->rtc;
 275         cros_ec = cros_ec_rtc->cros_ec;
 276
 277         host_event = cros_ec_get_host_event(cros_ec);
 278         if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_RTC)) {
 279                 rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
 280                 return NOTIFY_OK;
 281         } else {
 282                 return NOTIFY_DONE;
 283         }
 284 }
 285
 286 static const struct rtc_class_ops cros_ec_rtc_ops = {
 287         .read_time = cros_ec_rtc_read_time,
 288         .set_time = cros_ec_rtc_set_time,
 289         .read_alarm = cros_ec_rtc_read_alarm,
 290         .set_alarm = cros_ec_rtc_set_alarm,
 291         .alarm_irq_enable = cros_ec_rtc_alarm_irq_enable,
 292 };
 293
 294 #ifdef CONFIG_PM_SLEEP
 295 static int cros_ec_rtc_suspend(struct device *dev)
 296 {
 297         struct platform_device *pdev = to_platform_device(dev);
 298         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
 299
 300         if (device_may_wakeup(dev))
 301                 enable_irq_wake(cros_ec_rtc->cros_ec->irq);
 302
 303         return 0;
 304 }
 305
 306 static int cros_ec_rtc_resume(struct device *dev)
 307 {
 308         struct platform_device *pdev = to_platform_device(dev);
 309         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
 310
 311         if (device_may_wakeup(dev))
 312                 disable_irq_wake(cros_ec_rtc->cros_ec->irq);
 313
 314         return 0;
 315 }
 316 #endif
 317
 318 static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,
 319                          cros_ec_rtc_resume);
 320
 321 static int cros_ec_rtc_probe(struct platform_device *pdev)
 322 {
 323         struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
 324         struct cros_ec_device *cros_ec = ec_dev->ec_dev;
 325         struct cros_ec_rtc *cros_ec_rtc;
 326         struct rtc_time tm;
 327         int ret;
 328
 329         cros_ec_rtc = devm_kzalloc(&pdev->dev, sizeof(*cros_ec_rtc),
 330                                    GFP_KERNEL);
 331         if (!cros_ec_rtc)
 332                 return -ENOMEM;
 333
 334         platform_set_drvdata(pdev, cros_ec_rtc);
 335         cros_ec_rtc->cros_ec = cros_ec;
 336
 337         /* Get initial time */
 338         ret = cros_ec_rtc_read_time(&pdev->dev, &tm);
 339         if (ret) {
 340                 dev_err(&pdev->dev, "failed to read RTC time\n");
 341                 return ret;
 342         }
 343
 344         ret = device_init_wakeup(&pdev->dev, 1);
 345         if (ret) {
 346                 dev_err(&pdev->dev, "failed to initialize wakeup\n");
 347                 return ret;
 348         }
 349
 350         cros_ec_rtc->rtc = devm_rtc_device_register(&pdev->dev, DRV_NAME,
 351                                                     &cros_ec_rtc_ops,
 352                                                     THIS_MODULE);
 353         if (IS_ERR(cros_ec_rtc->rtc)) {
 354                 ret = PTR_ERR(cros_ec_rtc->rtc);
 355                 dev_err(&pdev->dev, "failed to register rtc device\n");
 356                 return ret;
 357         }
 358
 359         /* Get RTC events from the EC. */
 360         cros_ec_rtc->notifier.notifier_call = cros_ec_rtc_event;
 361         ret = blocking_notifier_chain_register(&cros_ec->event_notifier,
 362                                                &cros_ec_rtc->notifier);
 363         if (ret) {
 364                 dev_err(&pdev->dev, "failed to register notifier\n");
 365                 return ret;
 366         }
 367
 368         return 0;
 369 }
 370
 371 static int cros_ec_rtc_remove(struct platform_device *pdev)
 372 {
 373         struct cros_ec_rtc *cros_ec_rtc = platform_get_drvdata(pdev);
 374         struct device *dev = &pdev->dev;
 375         int ret;
 376
 377         ret = blocking_notifier_chain_unregister(
 378                                 &cros_ec_rtc->cros_ec->event_notifier,
 379                                 &cros_ec_rtc->notifier);
 380         if (ret) {
 381                 dev_err(dev, "failed to unregister notifier\n");
 382                 return ret;
 383         }
 384
 385         return 0;
 386 }
 387
 388 static struct platform_driver cros_ec_rtc_driver = {
 389         .probe = cros_ec_rtc_probe,
 390         .remove = cros_ec_rtc_remove,
 391         .driver = {
 392                 .name = DRV_NAME,
 393                 .pm = &cros_ec_rtc_pm_ops,
 394         },
 395 };
 396
 397 module_platform_driver(cros_ec_rtc_driver);
 398
 399 MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
 400 MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
 401 MODULE_LICENSE("GPL v2");
 402 MODULE_ALIAS("platform:" DRV_NAME);