drivers/rtc/rtc-cros-ec.c

   1 /*
   2  * RTC driver for Chrome OS Embedded Controller
   3  *
   4  * Copyright (c) 2017, Google, Inc
   5  *
   6  * Author: Stephen Barber <smbarber@chromium.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms and conditions of the GNU General Public License,
  10  * version 2, as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15  * more details.
  16  */
  17
  18 #include <linux/kernel.h>
  19 #include <linux/mfd/cros_ec.h>
  20 #include <linux/mfd/cros_ec_commands.h>
  21 #include <linux/module.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/rtc.h>
  24 #include <linux/slab.h>
  25
  26 #define DRV_NAME        "cros-ec-rtc"
  27
  28 /**
  29  * struct cros_ec_rtc - Driver data for EC RTC
  30  *
  31  * @cros_ec: Pointer to EC device
  32  * @rtc: Pointer to RTC device
  33  * @notifier: Notifier info for responding to EC events
  34  * @saved_alarm: Alarm to restore when interrupts are reenabled
  35  */
  36 struct cros_ec_rtc {
  37         struct cros_ec_device *cros_ec;
  38         struct rtc_device *rtc;
  39         struct notifier_block notifier;
  40         u32 saved_alarm;
  41 };
  42
  43 static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,
  44                            u32 *response)
  45 {
  46         int ret;
  47         struct {
  48                 struct cros_ec_command msg;
  49                 struct ec_response_rtc data;
  50         } __packed msg;
  51
  52         memset(&msg, 0, sizeof(msg));
  53         msg.msg.command = command;
  54         msg.msg.insize = sizeof(msg.data);
  55
  56         ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
  57         if (ret < 0) {
  58                 dev_err(cros_ec->dev,
  59                         "error getting %s from EC: %d\n",
  60                         command == EC_CMD_RTC_GET_VALUE ? "time" : "alarm",
  61                         ret);
  62                 return ret;
  63         }
  64
  65         *response = msg.data.time;
  66
  67         return 0;
  68 }
  69
  70 static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,
  71                            u32 param)
  72 {
  73         int ret = 0;
  74         struct {
  75                 struct cros_ec_command msg;
  76                 struct ec_response_rtc data;
  77         } __packed msg;
  78
  79         memset(&msg, 0, sizeof(msg));
  80         msg.msg.command = command;
  81         msg.msg.outsize = sizeof(msg.data);
  82         msg.data.time = param;
  83
  84         ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
  85         if (ret < 0) {
  86                 dev_err(cros_ec->dev, "error setting %s on EC: %d\n",
  87                         command == EC_CMD_RTC_SET_VALUE ? "time" : "alarm",
  88                         ret);
  89                 return ret;
  90         }
  91
  92         return 0;
  93 }
  94
  95 /* Read the current time from the EC. */
  96 static int cros_ec_rtc_read_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         u32 time;
 102
 103         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &time);
 104         if (ret) {
 105                 dev_err(dev, "error getting time: %d\n", ret);
 106                 return ret;
 107         }
 108
 109         rtc_time64_to_tm(time, tm);
 110
 111         return 0;
 112 }
 113
 114 /* Set the current EC time. */
 115 static int cros_ec_rtc_set_time(struct device *dev, struct rtc_time *tm)
 116 {
 117         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 118         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 119         int ret;
 120         time64_t time;
 121
 122         time = rtc_tm_to_time64(tm);
 123         if (time < 0 || time > U32_MAX)
 124                 return -EINVAL;
 125
 126         ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_VALUE, (u32)time);
 127         if (ret < 0) {
 128                 dev_err(dev, "error setting time: %d\n", ret);
 129                 return ret;
 130         }
 131
 132         return 0;
 133 }
 134
 135 /* Read alarm time from RTC. */
 136 static int cros_ec_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 137 {
 138         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 139         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 140         int ret;
 141         u32 current_time, alarm_offset;
 142
 143         /*
 144          * The EC host command for getting the alarm is relative (i.e. 5
 145          * seconds from now) whereas rtc_wkalrm is absolute. Get the current
 146          * RTC time first so we can calculate the relative time.
 147          */
 148         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 149         if (ret < 0) {
 150                 dev_err(dev, "error getting time: %d\n", ret);
 151                 return ret;
 152         }
 153
 154         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM, &alarm_offset);
 155         if (ret < 0) {
 156                 dev_err(dev, "error getting alarm: %d\n", ret);
 157                 return ret;
 158         }
 159
 160         rtc_time64_to_tm(current_time + alarm_offset, &alrm->time);
 161
 162         return 0;
 163 }
 164
 165 /* Set the EC's RTC alarm. */
 166 static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 167 {
 168         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 169         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 170         int ret;
 171         time64_t alarm_time;
 172         u32 current_time, alarm_offset;
 173
 174         /*
 175          * The EC host command for setting the alarm is relative
 176          * (i.e. 5 seconds from now) whereas rtc_wkalrm is absolute.
 177          * Get the current RTC time first so we can calculate the
 178          * relative time.
 179          */
 180         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 181         if (ret < 0) {
 182                 dev_err(dev, "error getting time: %d\n", ret);
 183                 return ret;
 184         }
 185
 186         alarm_time = rtc_tm_to_time64(&alrm->time);
 187
 188         if (alarm_time < 0 || alarm_time > U32_MAX)
 189                 return -EINVAL;
 190
 191         if (!alrm->enabled) {
 192                 /*
 193                  * If the alarm is being disabled, send an alarm
 194                  * clear command.
 195                  */
 196                 alarm_offset = EC_RTC_ALARM_CLEAR;
 197                 cros_ec_rtc->saved_alarm = (u32)alarm_time;
 198         } else {
 199                 /* Don't set an alarm in the past. */
 200                 if ((u32)alarm_time < current_time)
 201                         alarm_offset = EC_RTC_ALARM_CLEAR;
 202                 else
 203                         alarm_offset = (u32)alarm_time - current_time;
 204         }
 205
 206         ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
 207         if (ret < 0) {
 208                 dev_err(dev, "error setting alarm: %d\n", ret);
 209                 return ret;
 210         }
 211
 212         return 0;
 213 }
 214
 215 static int cros_ec_rtc_alarm_irq_enable(struct device *dev,
 216                                         unsigned int enabled)
 217 {
 218         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
 219         struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
 220         int ret;
 221         u32 current_time, alarm_offset, alarm_value;
 222
 223         ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
 224         if (ret < 0) {
 225                 dev_err(dev, "error getting time: %d\n", ret);
 226                 return ret;
 227         }
 228
 229         if (enabled) {
 230                 /* Restore saved alarm if it's still in the future. */
 231                 if (cros_ec_rtc->saved_alarm < current_time)
 232                         alarm_offset = EC_RTC_ALARM_CLEAR;
 233                 else
 234                         alarm_offset = cros_ec_rtc->saved_alarm - current_time;
 235
 236                 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
 237                                       alarm_offset);
 238                 if (ret < 0) {
 239                         dev_err(dev, "error restoring alarm: %d\n", ret);
 240                         return ret;
 241                 }
 242         } else {
 243                 /* Disable alarm, saving the old alarm value. */
 244                 ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM,
 245                                       &alarm_offset);
 246                 if (ret < 0) {
 247                         dev_err(dev, "error saving alarm: %d\n", ret);
 248                         return ret;
 249                 }
 250
 251                 alarm_value = current_time + alarm_offset;
 252
 253                 /*
 254                  * If the current EC alarm is already past, we don't want
 255                  * to set an alarm when we go through the alarm irq enable
 256                  * path.
 257                  */
 258                 if (alarm_value < current_time)
 259                         cros_ec_rtc->saved_alarm = EC_RTC_ALARM_CLEAR;
 260                 else
 261                         cros_ec_rtc->saved_alarm = alarm_value;
 262
 263                 alarm_offset = EC_RTC_ALARM_CLEAR;
 264                 ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
 265                                       alarm_offset);
 266                 if (ret < 0) {
 267                         dev_err(dev, "error disabling alarm: %d\n", ret);
 268                         return ret;
 269                 }
 270         }
 271
 272         return 0;
 273 }
 274
 275 static int cros_ec_rtc_event(struct notifier_block *nb,
 276                              unsigned long queued_during_suspend,
 277                              void *_notify)
 278 {
 279         struct cros_ec_rtc *cros_ec_rtc;
 280         struct rtc_device *rtc;
 281         struct cros_ec_device *cros_ec;
 282         u32 host_event;
 283
 284         cros_ec_rtc = container_of(nb, struct cros_ec_rtc, notifier);
 285         rtc = cros_ec_rtc->rtc;
 286         cros_ec = cros_ec_rtc->cros_ec;
 287
 288         host_event = cros_ec_get_host_event(cros_ec);
 289         if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_RTC)) {
 290                 rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
 291                 return NOTIFY_OK;
 292         } else {
 293                 return NOTIFY_DONE;
 294         }
 295 }
 296
 297 static const struct rtc_class_ops cros_ec_rtc_ops = {
 298         .read_time = cros_ec_rtc_read_time,
 299         .set_time = cros_ec_rtc_set_time,
 300         .read_alarm = cros_ec_rtc_read_alarm,
 301         .set_alarm = cros_ec_rtc_set_alarm,
 302         .alarm_irq_enable = cros_ec_rtc_alarm_irq_enable,
 303 };
 304
 305 #ifdef CONFIG_PM_SLEEP
 306 static int cros_ec_rtc_suspend(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                 enable_irq_wake(cros_ec_rtc->cros_ec->irq);
 313
 314         return 0;
 315 }
 316
 317 static int cros_ec_rtc_resume(struct device *dev)
 318 {
 319         struct platform_device *pdev = to_platform_device(dev);
 320         struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
 321
 322         if (device_may_wakeup(dev))
 323                 disable_irq_wake(cros_ec_rtc->cros_ec->irq);
 324
 325         return 0;
 326 }
 327 #endif
 328
 329 static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,
 330                          cros_ec_rtc_resume);
 331
 332 static int cros_ec_rtc_probe(struct platform_device *pdev)
 333 {
 334         struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
 335         struct cros_ec_device *cros_ec = ec_dev->ec_dev;
 336         struct cros_ec_rtc *cros_ec_rtc;
 337         struct rtc_time tm;
 338         int ret;
 339
 340         cros_ec_rtc = devm_kzalloc(&pdev->dev, sizeof(*cros_ec_rtc),
 341                                    GFP_KERNEL);
 342         if (!cros_ec_rtc)
 343                 return -ENOMEM;
 344
 345         platform_set_drvdata(pdev, cros_ec_rtc);
 346         cros_ec_rtc->cros_ec = cros_ec;
 347
 348         /* Get initial time */
 349         ret = cros_ec_rtc_read_time(&pdev->dev, &tm);
 350         if (ret) {
 351                 dev_err(&pdev->dev, "failed to read RTC time\n");
 352                 return ret;
 353         }
 354
 355         ret = device_init_wakeup(&pdev->dev, 1);
 356         if (ret) {
 357                 dev_err(&pdev->dev, "failed to initialize wakeup\n");
 358                 return ret;
 359         }
 360
 361         cros_ec_rtc->rtc = devm_rtc_device_register(&pdev->dev, DRV_NAME,
 362                                                     &cros_ec_rtc_ops,
 363                                                     THIS_MODULE);
 364         if (IS_ERR(cros_ec_rtc->rtc)) {
 365                 ret = PTR_ERR(cros_ec_rtc->rtc);
 366                 dev_err(&pdev->dev, "failed to register rtc device\n");
 367                 return ret;
 368         }
 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
 382 static int 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                 return ret;
 394         }
 395
 396         return 0;
 397 }
 398
 399 static struct platform_driver cros_ec_rtc_driver = {
 400         .probe = cros_ec_rtc_probe,
 401         .remove = cros_ec_rtc_remove,
 402         .driver = {
 403                 .name = DRV_NAME,
 404                 .pm = &cros_ec_rtc_pm_ops,
 405         },
 406 };
 407
 408 module_platform_driver(cros_ec_rtc_driver);
 409
 410 MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
 411 MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
 412 MODULE_LICENSE("GPL");
 413 MODULE_ALIAS("platform:" DRV_NAME);