LXR linux/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 */
  25struct 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
  32static 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
  59static 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. */
  85static 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. */
 104static 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. */
 121static 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. */
 151static 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
 200static 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
 260static 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
 282static 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
 291static 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
 302static 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
 314static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,
 315                         cros_ec_rtc_resume);
 316
 317static 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 = devm_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
 369static 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
 386static 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
 395module_platform_driver(cros_ec_rtc_driver);
 396
 397MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
 398MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
 399MODULE_LICENSE("GPL v2");
 400MODULE_ALIAS("platform:" DRV_NAME);
 401