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/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 /**
  19  * struct cros_ec_rtc - Driver data for EC RTC
  20  *
  21  * @cros_ec: Pointer to EC device
  22  * @rtc: Pointer to RTC device
  23  * @notifier: Notifier info for responding to EC events
  24  * @saved_alarm: Alarm to restore when interrupts are reenabled
  25  */
  26 struct cros_ec_rtc {
  27         struct cros_ec_device *cros_ec;
  28         struct rtc_device *rtc;
  29         struct notifier_block notifier;
  30         u32 saved_alarm;
  31 };
  32
  33 static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,
  34                            u32 *response)
  35 {
  36         int ret;
  37         struct {
  38                 struct cros_ec_command msg;
  39                 struct ec_response_rtc data;
  40         } __packed msg;
  41
  42         memset(&msg, 0, sizeof(msg));
  43         msg.msg.command = command;
  44         msg.msg.insize = sizeof(msg.data);
  45
  46         ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
  47         if (ret < 0) {
  48                 dev_err(cros_ec->dev,
  49                         "error getting %s from EC: %d\n",
  50                         command == EC_CMD_RTC_GET_VALUE ? "time" : "alarm",
  51                         ret);
  52                 return ret;
  53         }
  54
  55         *response = msg.data.time;
  56
  57         return 0;
  58 }
  59
  60 static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,
  61                            u32 param)
  62 {
  63         int ret = 0;
  64         struct {
  65                 struct cros_ec_command msg;
  66                 struct ec_response_rtc data;
  67         } __packed msg;
  68
  69         memset(&msg, 0, sizeof(msg));
  70         msg.msg.command = command;
  71         msg.msg.outsize = sizeof(msg.data);
  72         msg.data.time = param;
  73
  74         ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
  75         if (ret < 0) {
  76                 dev_err(cros_ec->dev, "error setting %s on EC: %d\n",
  77                         command == EC_CMD_RTC_SET_VALUE ? "time" : "alarm",
  78                         ret);
  79                 return ret;
  80         }
  81
  82         return 0;
  83 }
  84
  85 /* Read the current time from the EC. */
  86 static int cros_ec_rtc_read_time(struct device *dev, struct rtc_time *tm)
  87 {
  88         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
  89         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
  90         int ret;
  91         u32 time;
  92
  93         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &time);
  94         if (ret) {
  95                 dev_err(dev, "error getting time: %d\n", ret);
  96                 return ret;
  97         }
  98
  99         rtc_time64_to_tm(time, tm);
 100
 101         return 0;
 102 }
 103
 104 /* Set the current EC time. */
 105 static int cros_ec_rtc_set_time(struct device *dev, struct rtc_time *tm)
 106 {
 107         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 108         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 109         int ret;
 110         time64_t time = rtc_tm_to_time64(tm);
 111
 112         ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_VALUE, (u32)time);
 113         if (ret < 0) {
 114                 dev_err(dev, "error setting time: %d\n", ret);
 115                 return ret;
 116         }
 117
 118         return 0;
 119 }
 120
 121 /* Read alarm time from RTC. */
 122 static int cros_ec_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 123 {
 124         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 125         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 126         int ret;
 127         u32 current_time, alarm_offset;
 128
 129         /*
 130          * The EC host command for getting the alarm is relative (i.e. 5
 131          * seconds from now) whereas rtc_wkalrm is absolute. Get the current
 132          * RTC time first so we can calculate the relative time.
 133          */
 134         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 135         if (ret < 0) {
 136                 dev_err(dev, "error getting time: %d\n", ret);
 137                 return ret;
 138         }
 139
 140         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM, &alarm_offset);
 141         if (ret < 0) {
 142                 dev_err(dev, "error getting alarm: %d\n", ret);
 143                 return ret;
 144         }
 145
 146         rtc_time64_to_tm(current_time + alarm_offset, &alrm->time);
 147
 148         return 0;
 149 }
 150
 151 /* Set the EC's RTC alarm. */
 152 static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 153 {
 154         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 155         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 156         int ret;
 157         time64_t alarm_time;
 158         u32 current_time, alarm_offset;
 159
 160         /*
 161          * The EC host command for setting the alarm is relative
 162          * (i.e. 5 seconds from now) whereas rtc_wkalrm is absolute.
 163          * Get the current RTC time first so we can calculate the
 164          * relative time.
 165          */
 166         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 167         if (ret < 0) {
 168                 dev_err(dev, "error getting time: %d\n", ret);
 169                 return ret;
 170         }
 171
 172         alarm_time = rtc_tm_to_time64(&alrm->time);
 173
 174         if (alarm_time < 0 || alarm_time > U32_MAX)
 175                 return -EINVAL;
 176
 177         if (!alrm->enabled) {
 178                 /*
 179                  * If the alarm is being disabled, send an alarm
 180                  * clear command.
 181                  */
 182                 alarm_offset = EC_RTC_ALARM_CLEAR;
 183                 cros_ec_rtc->saved_alarm = (u32)alarm_time;
 184         } else {
 185                 /* Don't set an alarm in the past. */
 186                 if ((u32)alarm_time <= current_time)
 187                         return -ETIME;
 188
 189                 alarm_offset = (u32)alarm_time - current_time;
 190         }
 191
 192         ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
 193         if (ret < 0) {
 194                 dev_err(dev, "error setting alarm: %d\n", ret);
 195                 return ret;
 196         }
 197
 198         return 0;
 199 }
 200
 201 static int cros_ec_rtc_alarm_irq_enable(struct device *dev,
 202                                         unsigned int enabled)
 203 {
 204         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 205         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 206         int ret;
 207         u32 current_time, alarm_offset, alarm_value;
 208
 209         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 210         if (ret < 0) {
 211                 dev_err(dev, "error getting time: %d\n", ret);
 212                 return ret;
 213         }
 214
 215         if (enabled) {
 216                 /* Restore saved alarm if it's still in the future. */
 217                 if (cros_ec_rtc->saved_alarm < current_time)
 218                         alarm_offset = EC_RTC_ALARM_CLEAR;
 219                 else
 220                         alarm_offset = cros_ec_rtc->saved_alarm - current_time;
 221
 222                 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
 223                                       alarm_offset);
 224                 if (ret < 0) {
 225                         dev_err(dev, "error restoring alarm: %d\n", ret);
 226                         return ret;
 227                 }
 228         } else {
 229                 /* Disable alarm, saving the old alarm value. */
 230                 ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM,
 231                                       &alarm_offset);
 232                 if (ret < 0) {
 233                         dev_err(dev, "error saving alarm: %d\n", ret);
 234                         return ret;
 235                 }
 236
 237                 alarm_value = current_time + alarm_offset;
 238
 239                 /*
 240                  * If the current EC alarm is already past, we don't want
 241                  * to set an alarm when we go through the alarm irq enable
 242                  * path.
 243                  */
 244                 if (alarm_value < current_time)
 245                         cros_ec_rtc->saved_alarm = EC_RTC_ALARM_CLEAR;
 246                 else
 247                         cros_ec_rtc->saved_alarm = alarm_value;
 248
 249                 alarm_offset = EC_RTC_ALARM_CLEAR;
 250                 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
 251                                       alarm_offset);
 252                 if (ret < 0) {
 253                         dev_err(dev, "error disabling alarm: %d\n", ret);
 254                         return ret;
 255                 }
 256         }
 257
 258         return 0;
 259 }
 260
 261 static int cros_ec_rtc_event(struct notifier_block *nb,
 262                              unsigned long queued_during_suspend,
 263                              void *_notify)
 264 {
 265         struct cros_ec_rtc *cros_ec_rtc;
 266         struct rtc_device *rtc;
 267         struct cros_ec_device *cros_ec;
 268         u32 host_event;
 269
 270         cros_ec_rtc = container_of(nb, struct cros_ec_rtc, notifier);
 271         rtc = cros_ec_rtc->rtc;
 272         cros_ec = cros_ec_rtc->cros_ec;
 273
 274         host_event = cros_ec_get_host_event(cros_ec);
 275         if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_RTC)) {
 276                 rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
 277                 return NOTIFY_OK;
 278         } else {
 279                 return NOTIFY_DONE;
 280         }
 281 }
 282
 283 static const struct rtc_class_ops cros_ec_rtc_ops = {
 284         .read_time = cros_ec_rtc_read_time,
 285         .set_time = cros_ec_rtc_set_time,
 286         .read_alarm = cros_ec_rtc_read_alarm,
 287         .set_alarm = cros_ec_rtc_set_alarm,
 288         .alarm_irq_enable = cros_ec_rtc_alarm_irq_enable,
 289 };
 290
 291 #ifdef CONFIG_PM_SLEEP
 292 static int cros_ec_rtc_suspend(struct device *dev)
 293 {
 294         struct platform_device *pdev = to_platform_device(dev);
 295         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
 296
 297         if (device_may_wakeup(dev))
 298                 return enable_irq_wake(cros_ec_rtc->cros_ec->irq);
 299
 300         return 0;
 301 }
 302
 303 static int cros_ec_rtc_resume(struct device *dev)
 304 {
 305         struct platform_device *pdev = to_platform_device(dev);
 306         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
 307
 308         if (device_may_wakeup(dev))
 309                 return disable_irq_wake(cros_ec_rtc->cros_ec->irq);
 310
 311         return 0;
 312 }
 313 #endif
 314
 315 static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,
 316                          cros_ec_rtc_resume);
 317
 318 static int cros_ec_rtc_probe(struct platform_device *pdev)
 319 {
 320         struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
 321         struct cros_ec_device *cros_ec = ec_dev->ec_dev;
 322         struct cros_ec_rtc *cros_ec_rtc;
 323         struct rtc_time tm;
 324         int ret;
 325
 326         cros_ec_rtc = devm_kzalloc(&pdev->dev, sizeof(*cros_ec_rtc),
 327                                    GFP_KERNEL);
 328         if (!cros_ec_rtc)
 329                 return -ENOMEM;
 330
 331         platform_set_drvdata(pdev, cros_ec_rtc);
 332         cros_ec_rtc->cros_ec = cros_ec;
 333
 334         /* Get initial time */
 335         ret = cros_ec_rtc_read_time(&pdev->dev, &tm);
 336         if (ret) {
 337                 dev_err(&pdev->dev, "failed to read RTC time\n");
 338                 return ret;
 339         }
 340
 341         ret = device_init_wakeup(&pdev->dev, 1);
 342         if (ret) {
 343                 dev_err(&pdev->dev, "failed to initialize wakeup\n");
 344                 return ret;
 345         }
 346
 347         cros_ec_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
 348         if (IS_ERR(cros_ec_rtc->rtc))
 349                 return PTR_ERR(cros_ec_rtc->rtc);
 350
 351         cros_ec_rtc->rtc->ops = &cros_ec_rtc_ops;
 352         cros_ec_rtc->rtc->range_max = U32_MAX;
 353
 354         ret = rtc_register_device(cros_ec_rtc->rtc);
 355         if (ret)
 356                 return ret;
 357
 358         /* Get RTC events from the EC. */
 359         cros_ec_rtc->notifier.notifier_call = cros_ec_rtc_event;
 360         ret = blocking_notifier_chain_register(&cros_ec->event_notifier,
 361                                                &cros_ec_rtc->notifier);
 362         if (ret) {
 363                 dev_err(&pdev->dev, "failed to register notifier\n");
 364                 return ret;
 365         }
 366
 367         return 0;
 368 }
 369
 370 static int cros_ec_rtc_remove(struct platform_device *pdev)
 371 {
 372         struct cros_ec_rtc *cros_ec_rtc = platform_get_drvdata(pdev);
 373         struct device *dev = &pdev->dev;
 374         int ret;
 375
 376         ret = blocking_notifier_chain_unregister(
 377                                 &cros_ec_rtc->cros_ec->event_notifier,
 378                                 &cros_ec_rtc->notifier);
 379         if (ret) {
 380                 dev_err(dev, "failed to unregister notifier\n");
 381                 return ret;
 382         }
 383
 384         return 0;
 385 }
 386
 387 static struct platform_driver cros_ec_rtc_driver = {
 388         .probe = cros_ec_rtc_probe,
 389         .remove = cros_ec_rtc_remove,
 390         .driver = {
 391                 .name = DRV_NAME,
 392                 .pm = &cros_ec_rtc_pm_ops,
 393         },
 394 };
 395
 396 module_platform_driver(cros_ec_rtc_driver);
 397
 398 MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
 399 MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
 400 MODULE_LICENSE("GPL v2");
 401 MODULE_ALIAS("platform:" DRV_NAME);