Quelle  rtc-brcmstb-waketimer.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright © 2014-2023 Broadcom
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/clk.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irqreturn.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/reboot.h>
#include <linux/rtc.h>
#include <linux/stat.h>
#include <linux/suspend.h>

struct brcmstb_waketmr {
 struct rtc_device *rtc;
 struct device *dev;
 void __iomem *base;
 unsigned int wake_irq;
 unsigned int alarm_irq;
 struct notifier_block reboot_notifier;
 struct clk *clk;
 u32 rate;
 unsigned long rtc_alarm;
 bool alarm_en;
 bool alarm_expired;
};

#define BRCMSTB_WKTMR_EVENT  0x00
#define  WKTMR_ALARM_EVENT  BIT(0)
#define BRCMSTB_WKTMR_COUNTER  0x04
#define BRCMSTB_WKTMR_ALARM  0x08
#define BRCMSTB_WKTMR_PRESCALER  0x0C
#define BRCMSTB_WKTMR_PRESCALER_VAL 0x10

#define BRCMSTB_WKTMR_DEFAULT_FREQ 27000000

static inline bool brcmstb_waketmr_is_pending(struct brcmstb_waketmr *timer)
{
 u32 reg;

 reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
 return !!(reg & WKTMR_ALARM_EVENT);
}

static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
{
 u32 reg;

 if (timer->alarm_en && timer->alarm_irq)
  disable_irq(timer->alarm_irq);
 timer->alarm_en = false;
 reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
 writel_relaxed(reg - 1, timer->base + BRCMSTB_WKTMR_ALARM);
 writel_relaxed(WKTMR_ALARM_EVENT, timer->base + BRCMSTB_WKTMR_EVENT);
 (void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
 if (timer->alarm_expired) {
  timer->alarm_expired = false;
  /* maintain call balance */
  enable_irq(timer->alarm_irq);
 }
}

static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
          unsigned int secs)
{
 unsigned int now;

 brcmstb_waketmr_clear_alarm(timer);

 /* Make sure we are actually counting in seconds */
 writel_relaxed(timer->rate, timer->base + BRCMSTB_WKTMR_PRESCALER);

 writel_relaxed(secs, timer->base + BRCMSTB_WKTMR_ALARM);
 now = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);

 while ((int)(secs - now) <= 0 &&
  !brcmstb_waketmr_is_pending(timer)) {
  secs = now + 1;
  writel_relaxed(secs, timer->base + BRCMSTB_WKTMR_ALARM);
  now = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
 }
}

static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
{
 struct brcmstb_waketmr *timer = data;

 if (!timer->alarm_irq)
  pm_wakeup_event(timer->dev, 0);
 return IRQ_HANDLED;
}

static irqreturn_t brcmstb_alarm_irq(int irq, void *data)
{
 struct brcmstb_waketmr *timer = data;

 /* Ignore spurious interrupts */
 if (!brcmstb_waketmr_is_pending(timer))
  return IRQ_HANDLED;

 if (timer->alarm_en) {
  if (device_may_wakeup(timer->dev)) {
   disable_irq_nosync(irq);
   timer->alarm_expired = true;
  } else {
   writel_relaxed(WKTMR_ALARM_EVENT,
           timer->base + BRCMSTB_WKTMR_EVENT);
  }
  rtc_update_irq(timer->rtc, 1, RTC_IRQF | RTC_AF);
 } else {
  writel_relaxed(WKTMR_ALARM_EVENT,
          timer->base + BRCMSTB_WKTMR_EVENT);
 }

 return IRQ_HANDLED;
}

struct wktmr_time {
 u32 sec;
 u32 pre;
};

static void wktmr_read(struct brcmstb_waketmr *timer,
         struct wktmr_time *t)
{
 u32 tmp;

 do {
  t->sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
  tmp = readl_relaxed(timer->base + BRCMSTB_WKTMR_PRESCALER_VAL);
 } while (tmp >= timer->rate);

 t->pre = timer->rate - tmp;
}

static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
{
 struct device *dev = timer->dev;
 int ret;

 if (device_may_wakeup(dev)) {
  ret = enable_irq_wake(timer->wake_irq);
  if (ret) {
   dev_err(dev, "failed to enable wake-up interrupt\n");
   return ret;
  }
  if (timer->alarm_en && timer->alarm_irq) {
   ret = enable_irq_wake(timer->alarm_irq);
   if (ret) {
    dev_err(dev, "failed to enable rtc interrupt\n");
    disable_irq_wake(timer->wake_irq);
    return ret;
   }
  }
 }

 return 0;
}

/* If enabled as a wakeup-source, arm the timer when powering off */
static int brcmstb_waketmr_reboot(struct notifier_block *nb,
  unsigned long action, void *data)
{
 struct brcmstb_waketmr *timer;

 timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);

 /* Set timer for cold boot */
 if (action == SYS_POWER_OFF)
  brcmstb_waketmr_prepare_suspend(timer);

 return NOTIFY_DONE;
}

static int brcmstb_waketmr_gettime(struct device *dev,
       struct rtc_time *tm)
{
 struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 struct wktmr_time now;

 wktmr_read(timer, &now);

 rtc_time64_to_tm(now.sec, tm);

 return 0;
}

static int brcmstb_waketmr_settime(struct device *dev,
       struct rtc_time *tm)
{
 struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 time64_t sec;

 sec = rtc_tm_to_time64(tm);

 writel_relaxed(sec, timer->base + BRCMSTB_WKTMR_COUNTER);

 return 0;
}

static int brcmstb_waketmr_getalarm(struct device *dev,
        struct rtc_wkalrm *alarm)
{
 struct brcmstb_waketmr *timer = dev_get_drvdata(dev);

 alarm->enabled = timer->alarm_en;
 rtc_time64_to_tm(timer->rtc_alarm, &alarm->time);

 alarm->pending = brcmstb_waketmr_is_pending(timer);

 return 0;
}

static int brcmstb_waketmr_alarm_enable(struct device *dev,
     unsigned int enabled)
{
 struct brcmstb_waketmr *timer = dev_get_drvdata(dev);

 if (enabled && !timer->alarm_en) {
  if ((int)(readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER) -
      readl_relaxed(timer->base + BRCMSTB_WKTMR_ALARM)) >= 0 &&
      !brcmstb_waketmr_is_pending(timer))
   return -EINVAL;
  timer->alarm_en = true;
  if (timer->alarm_irq) {
   if (timer->alarm_expired) {
    timer->alarm_expired = false;
    /* maintain call balance */
    enable_irq(timer->alarm_irq);
   }
   enable_irq(timer->alarm_irq);
  }
 } else if (!enabled && timer->alarm_en) {
  if (timer->alarm_irq)
   disable_irq(timer->alarm_irq);
  timer->alarm_en = false;
 }

 return 0;
}

static int brcmstb_waketmr_setalarm(struct device *dev,
         struct rtc_wkalrm *alarm)
{
 struct brcmstb_waketmr *timer = dev_get_drvdata(dev);

 timer->rtc_alarm = rtc_tm_to_time64(&alarm->time);

 brcmstb_waketmr_set_alarm(timer, timer->rtc_alarm);

 return brcmstb_waketmr_alarm_enable(dev, alarm->enabled);
}

static const struct rtc_class_ops brcmstb_waketmr_ops = {
 .read_time = brcmstb_waketmr_gettime,
 .set_time = brcmstb_waketmr_settime,
 .read_alarm = brcmstb_waketmr_getalarm,
 .set_alarm = brcmstb_waketmr_setalarm,
 .alarm_irq_enable = brcmstb_waketmr_alarm_enable,
};

static int brcmstb_waketmr_probe(struct platform_device *pdev)
{
 struct device *dev = &pdev->dev;
 struct brcmstb_waketmr *timer;
 int ret;

 timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
 if (!timer)
  return -ENOMEM;

 platform_set_drvdata(pdev, timer);
 timer->dev = dev;

 timer->base = devm_platform_ioremap_resource(pdev, 0);
 if (IS_ERR(timer->base))
  return PTR_ERR(timer->base);

 timer->rtc = devm_rtc_allocate_device(dev);
 if (IS_ERR(timer->rtc))
  return PTR_ERR(timer->rtc);

 /*
 * Set wakeup capability before requesting wakeup interrupt, so we can
 * process boot-time "wakeups" (e.g., from S5 soft-off)
 */
 device_init_wakeup(dev, true);

 ret = platform_get_irq(pdev, 0);
 if (ret < 0)
  return -ENODEV;
 timer->wake_irq = (unsigned int)ret;

 timer->clk = devm_clk_get(dev, NULL);
 if (!IS_ERR(timer->clk)) {
  ret = clk_prepare_enable(timer->clk);
  if (ret)
   return ret;
  timer->rate = clk_get_rate(timer->clk);
  if (!timer->rate)
   timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
 } else {
  timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
  timer->clk = NULL;
 }

 ret = devm_request_irq(dev, timer->wake_irq, brcmstb_waketmr_irq, 0,
          "brcmstb-waketimer", timer);
 if (ret < 0)
  goto err_clk;

 brcmstb_waketmr_clear_alarm(timer);

 /* Attempt to initialize non-wake irq */
 ret = platform_get_irq(pdev, 1);
 if (ret > 0) {
  timer->alarm_irq = (unsigned int)ret;
  ret = devm_request_irq(dev, timer->alarm_irq, brcmstb_alarm_irq,
           IRQF_NO_AUTOEN, "brcmstb-waketimer-rtc",
           timer);
  if (ret < 0)
   timer->alarm_irq = 0;
 }

 timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
 register_reboot_notifier(&timer->reboot_notifier);

 timer->rtc->ops = &brcmstb_waketmr_ops;
 timer->rtc->range_max = U32_MAX;

 ret = devm_rtc_register_device(timer->rtc);
 if (ret)
  goto err_notifier;

 return 0;

err_notifier:
 unregister_reboot_notifier(&timer->reboot_notifier);

err_clk:
 clk_disable_unprepare(timer->clk);

 return ret;
}

static void brcmstb_waketmr_remove(struct platform_device *pdev)
{
 struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);

 unregister_reboot_notifier(&timer->reboot_notifier);
 clk_disable_unprepare(timer->clk);
}

#ifdef CONFIG_PM_SLEEP
static int brcmstb_waketmr_suspend(struct device *dev)
{
 struct brcmstb_waketmr *timer = dev_get_drvdata(dev);

 return brcmstb_waketmr_prepare_suspend(timer);
}

static int brcmstb_waketmr_suspend_noirq(struct device *dev)
{
 struct brcmstb_waketmr *timer = dev_get_drvdata(dev);

 /* Catch any alarms occurring prior to noirq */
 if (timer->alarm_expired && device_may_wakeup(dev))
  return -EBUSY;

 return 0;
}

static int brcmstb_waketmr_resume(struct device *dev)
{
 struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 int ret;

 if (!device_may_wakeup(dev))
  return 0;

 ret = disable_irq_wake(timer->wake_irq);
 if (timer->alarm_en && timer->alarm_irq)
  disable_irq_wake(timer->alarm_irq);

 brcmstb_waketmr_clear_alarm(timer);

 return ret;
}
#else
#define brcmstb_waketmr_suspend  NULL
#define brcmstb_waketmr_suspend_noirq NULL
#define brcmstb_waketmr_resume  NULL
#endif /* CONFIG_PM_SLEEP */

static const struct dev_pm_ops brcmstb_waketmr_pm_ops = {
 .suspend = brcmstb_waketmr_suspend,
 .suspend_noirq = brcmstb_waketmr_suspend_noirq,
 .resume  = brcmstb_waketmr_resume,
};

static const __maybe_unused struct of_device_id brcmstb_waketmr_of_match[] = {
 { .compatible = "brcm,brcmstb-waketimer" },
 { /* sentinel */ },
};

static struct platform_driver brcmstb_waketmr_driver = {
 .probe   = brcmstb_waketmr_probe,
 .remove   = brcmstb_waketmr_remove,
 .driver = {
  .name  = "brcmstb-waketimer",
  .pm  = &brcmstb_waketmr_pm_ops,
  .of_match_table = of_match_ptr(brcmstb_waketmr_of_match),
 }
};
module_platform_driver(brcmstb_waketmr_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Brian Norris");
MODULE_AUTHOR("Markus Mayer");
MODULE_AUTHOR("Doug Berger");
MODULE_DESCRIPTION("Wake-up timer driver for STB chips");