drivers/rtc/rtc-brcmstb-waketimer.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright © 2014-2023 Broadcom
   4  */
   5
   6 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
   7
   8 #include <linux/clk.h>
   9 #include <linux/device.h>
  10 #include <linux/err.h>
  11 #include <linux/init.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/io.h>
  14 #include <linux/irqreturn.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/pm.h>
  20 #include <linux/pm_wakeup.h>
  21 #include <linux/reboot.h>
  22 #include <linux/rtc.h>
  23 #include <linux/stat.h>
  24 #include <linux/suspend.h>
  25
  26 struct brcmstb_waketmr {
  27         struct rtc_device *rtc;
  28         struct device *dev;
  29         void __iomem *base;
  30         unsigned int wake_irq;
  31         unsigned int alarm_irq;
  32         struct notifier_block reboot_notifier;
  33         struct clk *clk;
  34         u32 rate;
  35         unsigned long rtc_alarm;
  36         bool alarm_en;
  37         bool alarm_expired;
  38 };
  39
  40 #define BRCMSTB_WKTMR_EVENT             0x00
  41 #define  WKTMR_ALARM_EVENT              BIT(0)
  42 #define BRCMSTB_WKTMR_COUNTER           0x04
  43 #define BRCMSTB_WKTMR_ALARM             0x08
  44 #define BRCMSTB_WKTMR_PRESCALER         0x0C
  45 #define BRCMSTB_WKTMR_PRESCALER_VAL     0x10
  46
  47 #define BRCMSTB_WKTMR_DEFAULT_FREQ      27000000
  48
  49 static inline bool brcmstb_waketmr_is_pending(struct brcmstb_waketmr *timer)
  50 {
  51         u32 reg;
  52
  53         reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
  54         return !!(reg & WKTMR_ALARM_EVENT);
  55 }
  56
  57 static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
  58 {
  59         u32 reg;
  60
  61         if (timer->alarm_en && timer->alarm_irq)
  62                 disable_irq(timer->alarm_irq);
  63         timer->alarm_en = false;
  64         reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
  65         writel_relaxed(reg - 1, timer->base + BRCMSTB_WKTMR_ALARM);
  66         writel_relaxed(WKTMR_ALARM_EVENT, timer->base + BRCMSTB_WKTMR_EVENT);
  67         (void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
  68         if (timer->alarm_expired) {
  69                 timer->alarm_expired = false;
  70                 /* maintain call balance */
  71                 enable_irq(timer->alarm_irq);
  72         }
  73 }
  74
  75 static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
  76                                       unsigned int secs)
  77 {
  78         unsigned int now;
  79
  80         brcmstb_waketmr_clear_alarm(timer);
  81
  82         /* Make sure we are actually counting in seconds */
  83         writel_relaxed(timer->rate, timer->base + BRCMSTB_WKTMR_PRESCALER);
  84
  85         writel_relaxed(secs, timer->base + BRCMSTB_WKTMR_ALARM);
  86         now = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
  87
  88         while ((int)(secs - now) <= 0 &&
  89                 !brcmstb_waketmr_is_pending(timer)) {
  90                 secs = now + 1;
  91                 writel_relaxed(secs, timer->base + BRCMSTB_WKTMR_ALARM);
  92                 now = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
  93         }
  94 }
  95
  96 static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
  97 {
  98         struct brcmstb_waketmr *timer = data;
  99
 100         if (!timer->alarm_irq)
 101                 pm_wakeup_event(timer->dev, 0);
 102         return IRQ_HANDLED;
 103 }
 104
 105 static irqreturn_t brcmstb_alarm_irq(int irq, void *data)
 106 {
 107         struct brcmstb_waketmr *timer = data;
 108
 109         /* Ignore spurious interrupts */
 110         if (!brcmstb_waketmr_is_pending(timer))
 111                 return IRQ_HANDLED;
 112
 113         if (timer->alarm_en) {
 114                 if (device_may_wakeup(timer->dev)) {
 115                         disable_irq_nosync(irq);
 116                         timer->alarm_expired = true;
 117                 } else {
 118                         writel_relaxed(WKTMR_ALARM_EVENT,
 119                                        timer->base + BRCMSTB_WKTMR_EVENT);
 120                 }
 121                 rtc_update_irq(timer->rtc, 1, RTC_IRQF | RTC_AF);
 122         } else {
 123                 writel_relaxed(WKTMR_ALARM_EVENT,
 124                                timer->base + BRCMSTB_WKTMR_EVENT);
 125         }
 126
 127         return IRQ_HANDLED;
 128 }
 129
 130 struct wktmr_time {
 131         u32 sec;
 132         u32 pre;
 133 };
 134
 135 static void wktmr_read(struct brcmstb_waketmr *timer,
 136                        struct wktmr_time *t)
 137 {
 138         u32 tmp;
 139
 140         do {
 141                 t->sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
 142                 tmp = readl_relaxed(timer->base + BRCMSTB_WKTMR_PRESCALER_VAL);
 143         } while (tmp >= timer->rate);
 144
 145         t->pre = timer->rate - tmp;
 146 }
 147
 148 static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
 149 {
 150         struct device *dev = timer->dev;
 151         int ret;
 152
 153         if (device_may_wakeup(dev)) {
 154                 ret = enable_irq_wake(timer->wake_irq);
 155                 if (ret) {
 156                         dev_err(dev, "failed to enable wake-up interrupt\n");
 157                         return ret;
 158                 }
 159                 if (timer->alarm_en && timer->alarm_irq) {
 160                         ret = enable_irq_wake(timer->alarm_irq);
 161                         if (ret) {
 162                                 dev_err(dev, "failed to enable rtc interrupt\n");
 163                                 disable_irq_wake(timer->wake_irq);
 164                                 return ret;
 165                         }
 166                 }
 167         }
 168
 169         return 0;
 170 }
 171
 172 /* If enabled as a wakeup-source, arm the timer when powering off */
 173 static int brcmstb_waketmr_reboot(struct notifier_block *nb,
 174                 unsigned long action, void *data)
 175 {
 176         struct brcmstb_waketmr *timer;
 177
 178         timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);
 179
 180         /* Set timer for cold boot */
 181         if (action == SYS_POWER_OFF)
 182                 brcmstb_waketmr_prepare_suspend(timer);
 183
 184         return NOTIFY_DONE;
 185 }
 186
 187 static int brcmstb_waketmr_gettime(struct device *dev,
 188                                    struct rtc_time *tm)
 189 {
 190         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 191         struct wktmr_time now;
 192
 193         wktmr_read(timer, &now);
 194
 195         rtc_time64_to_tm(now.sec, tm);
 196
 197         return 0;
 198 }
 199
 200 static int brcmstb_waketmr_settime(struct device *dev,
 201                                    struct rtc_time *tm)
 202 {
 203         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 204         time64_t sec;
 205
 206         sec = rtc_tm_to_time64(tm);
 207
 208         writel_relaxed(sec, timer->base + BRCMSTB_WKTMR_COUNTER);
 209
 210         return 0;
 211 }
 212
 213 static int brcmstb_waketmr_getalarm(struct device *dev,
 214                                     struct rtc_wkalrm *alarm)
 215 {
 216         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 217
 218         alarm->enabled = timer->alarm_en;
 219         rtc_time64_to_tm(timer->rtc_alarm, &alarm->time);
 220
 221         alarm->pending = brcmstb_waketmr_is_pending(timer);
 222
 223         return 0;
 224 }
 225
 226 static int brcmstb_waketmr_alarm_enable(struct device *dev,
 227                                         unsigned int enabled)
 228 {
 229         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 230
 231         if (enabled && !timer->alarm_en) {
 232                 if ((int)(readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER) -
 233                     readl_relaxed(timer->base + BRCMSTB_WKTMR_ALARM)) >= 0 &&
 234                     !brcmstb_waketmr_is_pending(timer))
 235                         return -EINVAL;
 236                 timer->alarm_en = true;
 237                 if (timer->alarm_irq) {
 238                         if (timer->alarm_expired) {
 239                                 timer->alarm_expired = false;
 240                                 /* maintain call balance */
 241                                 enable_irq(timer->alarm_irq);
 242                         }
 243                         enable_irq(timer->alarm_irq);
 244                 }
 245         } else if (!enabled && timer->alarm_en) {
 246                 if (timer->alarm_irq)
 247                         disable_irq(timer->alarm_irq);
 248                 timer->alarm_en = false;
 249         }
 250
 251         return 0;
 252 }
 253
 254 static int brcmstb_waketmr_setalarm(struct device *dev,
 255                                      struct rtc_wkalrm *alarm)
 256 {
 257         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 258
 259         timer->rtc_alarm = rtc_tm_to_time64(&alarm->time);
 260
 261         brcmstb_waketmr_set_alarm(timer, timer->rtc_alarm);
 262
 263         return brcmstb_waketmr_alarm_enable(dev, alarm->enabled);
 264 }
 265
 266 static const struct rtc_class_ops brcmstb_waketmr_ops = {
 267         .read_time      = brcmstb_waketmr_gettime,
 268         .set_time       = brcmstb_waketmr_settime,
 269         .read_alarm     = brcmstb_waketmr_getalarm,
 270         .set_alarm      = brcmstb_waketmr_setalarm,
 271         .alarm_irq_enable = brcmstb_waketmr_alarm_enable,
 272 };
 273
 274 static int brcmstb_waketmr_probe(struct platform_device *pdev)
 275 {
 276         struct device *dev = &pdev->dev;
 277         struct brcmstb_waketmr *timer;
 278         int ret;
 279
 280         timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
 281         if (!timer)
 282                 return -ENOMEM;
 283
 284         platform_set_drvdata(pdev, timer);
 285         timer->dev = dev;
 286
 287         timer->base = devm_platform_ioremap_resource(pdev, 0);
 288         if (IS_ERR(timer->base))
 289                 return PTR_ERR(timer->base);
 290
 291         timer->rtc = devm_rtc_allocate_device(dev);
 292         if (IS_ERR(timer->rtc))
 293                 return PTR_ERR(timer->rtc);
 294
 295         /*
 296          * Set wakeup capability before requesting wakeup interrupt, so we can
 297          * process boot-time "wakeups" (e.g., from S5 soft-off)
 298          */
 299         device_init_wakeup(dev, true);
 300
 301         ret = platform_get_irq(pdev, 0);
 302         if (ret < 0)
 303                 return -ENODEV;
 304         timer->wake_irq = (unsigned int)ret;
 305
 306         timer->clk = devm_clk_get(dev, NULL);
 307         if (!IS_ERR(timer->clk)) {
 308                 ret = clk_prepare_enable(timer->clk);
 309                 if (ret)
 310                         return ret;
 311                 timer->rate = clk_get_rate(timer->clk);
 312                 if (!timer->rate)
 313                         timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
 314         } else {
 315                 timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
 316                 timer->clk = NULL;
 317         }
 318
 319         ret = devm_request_irq(dev, timer->wake_irq, brcmstb_waketmr_irq, 0,
 320                                "brcmstb-waketimer", timer);
 321         if (ret < 0)
 322                 goto err_clk;
 323
 324         brcmstb_waketmr_clear_alarm(timer);
 325
 326         /* Attempt to initialize non-wake irq */
 327         ret = platform_get_irq(pdev, 1);
 328         if (ret > 0) {
 329                 timer->alarm_irq = (unsigned int)ret;
 330                 ret = devm_request_irq(dev, timer->alarm_irq, brcmstb_alarm_irq,
 331                                        IRQF_NO_AUTOEN, "brcmstb-waketimer-rtc",
 332                                        timer);
 333                 if (ret < 0)
 334                         timer->alarm_irq = 0;
 335         }
 336
 337         timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
 338         register_reboot_notifier(&timer->reboot_notifier);
 339
 340         timer->rtc->ops = &brcmstb_waketmr_ops;
 341         timer->rtc->range_max = U32_MAX;
 342
 343         ret = devm_rtc_register_device(timer->rtc);
 344         if (ret)
 345                 goto err_notifier;
 346
 347         return 0;
 348
 349 err_notifier:
 350         unregister_reboot_notifier(&timer->reboot_notifier);
 351
 352 err_clk:
 353         clk_disable_unprepare(timer->clk);
 354
 355         return ret;
 356 }
 357
 358 static void brcmstb_waketmr_remove(struct platform_device *pdev)
 359 {
 360         struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);
 361
 362         unregister_reboot_notifier(&timer->reboot_notifier);
 363         clk_disable_unprepare(timer->clk);
 364 }
 365
 366 #ifdef CONFIG_PM_SLEEP
 367 static int brcmstb_waketmr_suspend(struct device *dev)
 368 {
 369         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 370
 371         return brcmstb_waketmr_prepare_suspend(timer);
 372 }
 373
 374 static int brcmstb_waketmr_suspend_noirq(struct device *dev)
 375 {
 376         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 377
 378         /* Catch any alarms occurring prior to noirq */
 379         if (timer->alarm_expired && device_may_wakeup(dev))
 380                 return -EBUSY;
 381
 382         return 0;
 383 }
 384
 385 static int brcmstb_waketmr_resume(struct device *dev)
 386 {
 387         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 388         int ret;
 389
 390         if (!device_may_wakeup(dev))
 391                 return 0;
 392
 393         ret = disable_irq_wake(timer->wake_irq);
 394         if (timer->alarm_en && timer->alarm_irq)
 395                 disable_irq_wake(timer->alarm_irq);
 396
 397         brcmstb_waketmr_clear_alarm(timer);
 398
 399         return ret;
 400 }
 401 #else
 402 #define brcmstb_waketmr_suspend         NULL
 403 #define brcmstb_waketmr_suspend_noirq   NULL
 404 #define brcmstb_waketmr_resume          NULL
 405 #endif /* CONFIG_PM_SLEEP */
 406
 407 static const struct dev_pm_ops brcmstb_waketmr_pm_ops = {
 408         .suspend        = brcmstb_waketmr_suspend,
 409         .suspend_noirq  = brcmstb_waketmr_suspend_noirq,
 410         .resume         = brcmstb_waketmr_resume,
 411 };
 412
 413 static const __maybe_unused struct of_device_id brcmstb_waketmr_of_match[] = {
 414         { .compatible = "brcm,brcmstb-waketimer" },
 415         { /* sentinel */ },
 416 };
 417
 418 static struct platform_driver brcmstb_waketmr_driver = {
 419         .probe                  = brcmstb_waketmr_probe,
 420         .remove_new             = brcmstb_waketmr_remove,
 421         .driver = {
 422                 .name           = "brcmstb-waketimer",
 423                 .pm             = &brcmstb_waketmr_pm_ops,
 424                 .of_match_table = of_match_ptr(brcmstb_waketmr_of_match),
 425         }
 426 };
 427 module_platform_driver(brcmstb_waketmr_driver);
 428
 429 MODULE_LICENSE("GPL v2");
 430 MODULE_AUTHOR("Brian Norris");
 431 MODULE_AUTHOR("Markus Mayer");
 432 MODULE_AUTHOR("Doug Berger");
 433 MODULE_DESCRIPTION("Wake-up timer driver for STB chips");