linux/drivers/rtc/rtc-brcmstb-waketimer.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright \xC2\xA9 2014-2017 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
  26struct brcmstb_waketmr {
  27        struct rtc_device *rtc;
  28        struct device *dev;
  29        void __iomem *base;
  30        int irq;
  31        struct notifier_block reboot_notifier;
  32        struct clk *clk;
  33        u32 rate;
  34};
  35
  36#define BRCMSTB_WKTMR_EVENT             0x00
  37#define BRCMSTB_WKTMR_COUNTER           0x04
  38#define BRCMSTB_WKTMR_ALARM             0x08
  39#define BRCMSTB_WKTMR_PRESCALER         0x0C
  40#define BRCMSTB_WKTMR_PRESCALER_VAL     0x10
  41
  42#define BRCMSTB_WKTMR_DEFAULT_FREQ      27000000
  43
  44static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
  45{
  46        writel_relaxed(1, timer->base + BRCMSTB_WKTMR_EVENT);
  47        (void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
  48}
  49
  50static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
  51                                      unsigned int secs)
  52{
  53        brcmstb_waketmr_clear_alarm(timer);
  54
  55        /* Make sure we are actually counting in seconds */
  56        writel_relaxed(timer->rate, timer->base + BRCMSTB_WKTMR_PRESCALER);
  57
  58        writel_relaxed(secs + 1, timer->base + BRCMSTB_WKTMR_ALARM);
  59}
  60
  61static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
  62{
  63        struct brcmstb_waketmr *timer = data;
  64
  65        pm_wakeup_event(timer->dev, 0);
  66
  67        return IRQ_HANDLED;
  68}
  69
  70struct wktmr_time {
  71        u32 sec;
  72        u32 pre;
  73};
  74
  75static void wktmr_read(struct brcmstb_waketmr *timer,
  76                       struct wktmr_time *t)
  77{
  78        u32 tmp;
  79
  80        do {
  81                t->sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
  82                tmp = readl_relaxed(timer->base + BRCMSTB_WKTMR_PRESCALER_VAL);
  83        } while (tmp >= timer->rate);
  84
  85        t->pre = timer->rate - tmp;
  86}
  87
  88static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
  89{
  90        struct device *dev = timer->dev;
  91        int ret = 0;
  92
  93        if (device_may_wakeup(dev)) {
  94                ret = enable_irq_wake(timer->irq);
  95                if (ret) {
  96                        dev_err(dev, "failed to enable wake-up interrupt\n");
  97                        return ret;
  98                }
  99        }
 100
 101        return ret;
 102}
 103
 104/* If enabled as a wakeup-source, arm the timer when powering off */
 105static int brcmstb_waketmr_reboot(struct notifier_block *nb,
 106                unsigned long action, void *data)
 107{
 108        struct brcmstb_waketmr *timer;
 109
 110        timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);
 111
 112        /* Set timer for cold boot */
 113        if (action == SYS_POWER_OFF)
 114                brcmstb_waketmr_prepare_suspend(timer);
 115
 116        return NOTIFY_DONE;
 117}
 118
 119static int brcmstb_waketmr_gettime(struct device *dev,
 120                                   struct rtc_time *tm)
 121{
 122        struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 123        struct wktmr_time now;
 124
 125        wktmr_read(timer, &now);
 126
 127        rtc_time64_to_tm(now.sec, tm);
 128
 129        return 0;
 130}
 131
 132static int brcmstb_waketmr_settime(struct device *dev,
 133                                   struct rtc_time *tm)
 134{
 135        struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 136        time64_t sec;
 137
 138        sec = rtc_tm_to_time64(tm);
 139
 140        writel_relaxed(sec, timer->base + BRCMSTB_WKTMR_COUNTER);
 141
 142        return 0;
 143}
 144
 145static int brcmstb_waketmr_getalarm(struct device *dev,
 146                                    struct rtc_wkalrm *alarm)
 147{
 148        struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 149        time64_t sec;
 150        u32 reg;
 151
 152        sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_ALARM);
 153        if (sec != 0) {
 154                /* Alarm is enabled */
 155                alarm->enabled = 1;
 156                rtc_time64_to_tm(sec, &alarm->time);
 157        }
 158
 159        reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
 160        alarm->pending = !!(reg & 1);
 161
 162        return 0;
 163}
 164
 165static int brcmstb_waketmr_setalarm(struct device *dev,
 166                                     struct rtc_wkalrm *alarm)
 167{
 168        struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 169        time64_t sec;
 170
 171        if (alarm->enabled)
 172                sec = rtc_tm_to_time64(&alarm->time);
 173        else
 174                sec = 0;
 175
 176        brcmstb_waketmr_set_alarm(timer, sec);
 177
 178        return 0;
 179}
 180
 181/*
 182 * Does not do much but keep the RTC class happy. We always support
 183 * alarms.
 184 */
 185static int brcmstb_waketmr_alarm_enable(struct device *dev,
 186                                        unsigned int enabled)
 187{
 188        return 0;
 189}
 190
 191static const struct rtc_class_ops brcmstb_waketmr_ops = {
 192        .read_time      = brcmstb_waketmr_gettime,
 193        .set_time       = brcmstb_waketmr_settime,
 194        .read_alarm     = brcmstb_waketmr_getalarm,
 195        .set_alarm      = brcmstb_waketmr_setalarm,
 196        .alarm_irq_enable = brcmstb_waketmr_alarm_enable,
 197};
 198
 199static int brcmstb_waketmr_probe(struct platform_device *pdev)
 200{
 201        struct device *dev = &pdev->dev;
 202        struct brcmstb_waketmr *timer;
 203        int ret;
 204
 205        timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
 206        if (!timer)
 207                return -ENOMEM;
 208
 209        platform_set_drvdata(pdev, timer);
 210        timer->dev = dev;
 211
 212        timer->base = devm_platform_ioremap_resource(pdev, 0);
 213        if (IS_ERR(timer->base))
 214                return PTR_ERR(timer->base);
 215
 216        timer->rtc = devm_rtc_allocate_device(dev);
 217        if (IS_ERR(timer->rtc))
 218                return PTR_ERR(timer->rtc);
 219
 220        /*
 221         * Set wakeup capability before requesting wakeup interrupt, so we can
 222         * process boot-time "wakeups" (e.g., from S5 soft-off)
 223         */
 224        device_set_wakeup_capable(dev, true);
 225        device_wakeup_enable(dev);
 226
 227        timer->irq = platform_get_irq(pdev, 0);
 228        if (timer->irq < 0)
 229                return -ENODEV;
 230
 231        timer->clk = devm_clk_get(dev, NULL);
 232        if (!IS_ERR(timer->clk)) {
 233                ret = clk_prepare_enable(timer->clk);
 234                if (ret)
 235                        return ret;
 236                timer->rate = clk_get_rate(timer->clk);
 237                if (!timer->rate)
 238                        timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
 239        } else {
 240                timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
 241                timer->clk = NULL;
 242        }
 243
 244        ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
 245                               "brcmstb-waketimer", timer);
 246        if (ret < 0)
 247                goto err_clk;
 248
 249        timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
 250        register_reboot_notifier(&timer->reboot_notifier);
 251
 252        timer->rtc->ops = &brcmstb_waketmr_ops;
 253        timer->rtc->range_max = U32_MAX;
 254
 255        ret = devm_rtc_register_device(timer->rtc);
 256        if (ret)
 257                goto err_notifier;
 258
 259        dev_info(dev, "registered, with irq %d\n", timer->irq);
 260
 261        return 0;
 262
 263err_notifier:
 264        unregister_reboot_notifier(&timer->reboot_notifier);
 265
 266err_clk:
 267        clk_disable_unprepare(timer->clk);
 268
 269        return ret;
 270}
 271
 272static int brcmstb_waketmr_remove(struct platform_device *pdev)
 273{
 274        struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);
 275
 276        unregister_reboot_notifier(&timer->reboot_notifier);
 277        clk_disable_unprepare(timer->clk);
 278
 279        return 0;
 280}
 281
 282#ifdef CONFIG_PM_SLEEP
 283static int brcmstb_waketmr_suspend(struct device *dev)
 284{
 285        struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 286
 287        return brcmstb_waketmr_prepare_suspend(timer);
 288}
 289
 290static int brcmstb_waketmr_resume(struct device *dev)
 291{
 292        struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 293        int ret;
 294
 295        if (!device_may_wakeup(dev))
 296                return 0;
 297
 298        ret = disable_irq_wake(timer->irq);
 299
 300        brcmstb_waketmr_clear_alarm(timer);
 301
 302        return ret;
 303}
 304#endif /* CONFIG_PM_SLEEP */
 305
 306static SIMPLE_DEV_PM_OPS(brcmstb_waketmr_pm_ops,
 307                         brcmstb_waketmr_suspend, brcmstb_waketmr_resume);
 308
 309static const __maybe_unused struct of_device_id brcmstb_waketmr_of_match[] = {
 310        { .compatible = "brcm,brcmstb-waketimer" },
 311        { /* sentinel */ },
 312};
 313
 314static struct platform_driver brcmstb_waketmr_driver = {
 315        .probe                  = brcmstb_waketmr_probe,
 316        .remove                 = brcmstb_waketmr_remove,
 317        .driver = {
 318                .name           = "brcmstb-waketimer",
 319                .pm             = &brcmstb_waketmr_pm_ops,
 320                .of_match_table = of_match_ptr(brcmstb_waketmr_of_match),
 321        }
 322};
 323module_platform_driver(brcmstb_waketmr_driver);
 324
 325MODULE_LICENSE("GPL v2");
 326MODULE_AUTHOR("Brian Norris");
 327MODULE_AUTHOR("Markus Mayer");
 328MODULE_DESCRIPTION("Wake-up timer driver for STB chips");
 329