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