// SPDX-License-Identifier: GPL-2.0+

  /*
   *	Real Time Clock driver for Wolfson Microelectronics WM831x
   *
   *	Copyright (C) 2009 Wolfson Microelectronics PLC.
   *
   *  Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
   *

   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/time.h>
  #include <linux/rtc.h>

  #include <linux/slab.h>

  #include <linux/bcd.h>
  #include <linux/interrupt.h>
  #include <linux/ioctl.h>
  #include <linux/completion.h>
  #include <linux/mfd/wm831x/core.h>
  #include <linux/delay.h>
  #include <linux/platform_device.h>

  #include <linux/random.h>

  
  /*
   * R16416 (0x4020) - RTC Write Counter
   */
  #define WM831X_RTC_WR_CNT_MASK                  0xFFFF  /* RTC_WR_CNT - [15:0] */
  #define WM831X_RTC_WR_CNT_SHIFT                      0  /* RTC_WR_CNT - [15:0] */
  #define WM831X_RTC_WR_CNT_WIDTH                     16  /* RTC_WR_CNT - [15:0] */
  
  /*
   * R16417 (0x4021) - RTC Time 1
   */
  #define WM831X_RTC_TIME_MASK                    0xFFFF  /* RTC_TIME - [15:0] */
  #define WM831X_RTC_TIME_SHIFT                        0  /* RTC_TIME - [15:0] */
  #define WM831X_RTC_TIME_WIDTH                       16  /* RTC_TIME - [15:0] */
  
  /*
   * R16418 (0x4022) - RTC Time 2
   */
  #define WM831X_RTC_TIME_MASK                    0xFFFF  /* RTC_TIME - [15:0] */
  #define WM831X_RTC_TIME_SHIFT                        0  /* RTC_TIME - [15:0] */
  #define WM831X_RTC_TIME_WIDTH                       16  /* RTC_TIME - [15:0] */
  
  /*
   * R16419 (0x4023) - RTC Alarm 1
   */
  #define WM831X_RTC_ALM_MASK                     0xFFFF  /* RTC_ALM - [15:0] */
  #define WM831X_RTC_ALM_SHIFT                         0  /* RTC_ALM - [15:0] */
  #define WM831X_RTC_ALM_WIDTH                        16  /* RTC_ALM - [15:0] */
  
  /*
   * R16420 (0x4024) - RTC Alarm 2
   */
  #define WM831X_RTC_ALM_MASK                     0xFFFF  /* RTC_ALM - [15:0] */
  #define WM831X_RTC_ALM_SHIFT                         0  /* RTC_ALM - [15:0] */
  #define WM831X_RTC_ALM_WIDTH                        16  /* RTC_ALM - [15:0] */
  
  /*
   * R16421 (0x4025) - RTC Control
   */
  #define WM831X_RTC_VALID                        0x8000  /* RTC_VALID */
  #define WM831X_RTC_VALID_MASK                   0x8000  /* RTC_VALID */
  #define WM831X_RTC_VALID_SHIFT                      15  /* RTC_VALID */
  #define WM831X_RTC_VALID_WIDTH                       1  /* RTC_VALID */
  #define WM831X_RTC_SYNC_BUSY                    0x4000  /* RTC_SYNC_BUSY */
  #define WM831X_RTC_SYNC_BUSY_MASK               0x4000  /* RTC_SYNC_BUSY */
  #define WM831X_RTC_SYNC_BUSY_SHIFT                  14  /* RTC_SYNC_BUSY */
  #define WM831X_RTC_SYNC_BUSY_WIDTH                   1  /* RTC_SYNC_BUSY */
  #define WM831X_RTC_ALM_ENA                      0x0400  /* RTC_ALM_ENA */
  #define WM831X_RTC_ALM_ENA_MASK                 0x0400  /* RTC_ALM_ENA */
  #define WM831X_RTC_ALM_ENA_SHIFT                    10  /* RTC_ALM_ENA */
  #define WM831X_RTC_ALM_ENA_WIDTH                     1  /* RTC_ALM_ENA */
  #define WM831X_RTC_PINT_FREQ_MASK               0x0070  /* RTC_PINT_FREQ - [6:4] */
  #define WM831X_RTC_PINT_FREQ_SHIFT                   4  /* RTC_PINT_FREQ - [6:4] */
  #define WM831X_RTC_PINT_FREQ_WIDTH                   3  /* RTC_PINT_FREQ - [6:4] */
  
  /*
   * R16422 (0x4026) - RTC Trim
   */
  #define WM831X_RTC_TRIM_MASK                    0x03FF  /* RTC_TRIM - [9:0] */
  #define WM831X_RTC_TRIM_SHIFT                        0  /* RTC_TRIM - [9:0] */
  #define WM831X_RTC_TRIM_WIDTH                       10  /* RTC_TRIM - [9:0] */
  
  #define WM831X_SET_TIME_RETRIES	5
  #define WM831X_GET_TIME_RETRIES	5
  
  struct wm831x_rtc {
  	struct wm831x *wm831x;
  	struct rtc_device *rtc;
  	unsigned int alarm_enabled:1;
  };

  static void wm831x_rtc_add_randomness(struct wm831x *wm831x)
  {
  	int ret;
  	u16 reg;
  
  	/*
  	 * The write counter contains a pseudo-random number which is
  	 * regenerated every time we set the RTC so it should be a
  	 * useful per-system source of entropy.
  	 */
  	ret = wm831x_reg_read(wm831x, WM831X_RTC_WRITE_COUNTER);
  	if (ret >= 0) {
  		reg = ret;
  		add_device_randomness(&reg, sizeof(reg));
  	} else {
  		dev_warn(wm831x->dev, "Failed to read RTC write counter: %d
  ",
  			 ret);
  	}
  }

  /*
   * Read current time and date in RTC
   */
  static int wm831x_rtc_readtime(struct device *dev, struct rtc_time *tm)
  {
  	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
  	struct wm831x *wm831x = wm831x_rtc->wm831x;
  	u16 time1[2], time2[2];
  	int ret;
  	int count = 0;
  
  	/* Has the RTC been programmed? */
  	ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
  	if (ret < 0) {
  		dev_err(dev, "Failed to read RTC control: %d
  ", ret);
  		return ret;
  	}
  	if (!(ret & WM831X_RTC_VALID)) {
  		dev_dbg(dev, "RTC not yet configured
  ");
  		return -EINVAL;
  	}
  
  	/* Read twice to make sure we don't read a corrupt, partially
  	 * incremented, value.
  	 */
  	do {
  		ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
  				       2, time1);
  		if (ret != 0)
  			continue;
  
  		ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
  				       2, time2);
  		if (ret != 0)
  			continue;
  
  		if (memcmp(time1, time2, sizeof(time1)) == 0) {
  			u32 time = (time1[0] << 16) | time1[1];

  			rtc_time64_to_tm(time, tm);

  			return 0;

  		}
  
  	} while (++count < WM831X_GET_TIME_RETRIES);
  
  	dev_err(dev, "Timed out reading current time
  ");
  
  	return -EIO;
  }
  
  /*
   * Set current time and date in RTC
   */

  static int wm831x_rtc_settime(struct device *dev, struct rtc_time *tm)

  {
  	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
  	struct wm831x *wm831x = wm831x_rtc->wm831x;
  	struct rtc_time new_tm;

  	unsigned long time, new_time;

  	int ret;
  	int count = 0;

  	time = rtc_tm_to_time64(tm);

  	ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_1,
  			       (time >> 16) & 0xffff);
  	if (ret < 0) {
  		dev_err(dev, "Failed to write TIME_1: %d
  ", ret);
  		return ret;
  	}
  
  	ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_2, time & 0xffff);
  	if (ret < 0) {
  		dev_err(dev, "Failed to write TIME_2: %d
  ", ret);
  		return ret;
  	}
  
  	/* Wait for the update to complete - should happen first time
  	 * round but be conservative.
  	 */
  	do {
  		msleep(1);
  
  		ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
  		if (ret < 0)
  			ret = WM831X_RTC_SYNC_BUSY;
  	} while (!(ret & WM831X_RTC_SYNC_BUSY) &&
  		 ++count < WM831X_SET_TIME_RETRIES);
  
  	if (ret & WM831X_RTC_SYNC_BUSY) {
  		dev_err(dev, "Timed out writing RTC update
  ");
  		return -EIO;
  	}
  
  	/* Check that the update was accepted; security features may
  	 * have caused the update to be ignored.
  	 */
  	ret = wm831x_rtc_readtime(dev, &new_tm);
  	if (ret < 0)
  		return ret;

  	new_time = rtc_tm_to_time64(&new_tm);

  
  	/* Allow a second of change in case of tick */
  	if (new_time - time > 1) {
  		dev_err(dev, "RTC update not permitted by hardware
  ");
  		return -EPERM;
  	}
  
  	return 0;
  }
  
  /*
   * Read alarm time and date in RTC
   */
  static int wm831x_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
  	int ret;
  	u16 data[2];
  	u32 time;
  
  	ret = wm831x_bulk_read(wm831x_rtc->wm831x, WM831X_RTC_ALARM_1,
  			       2, data);
  	if (ret != 0) {
  		dev_err(dev, "Failed to read alarm time: %d
  ", ret);
  		return ret;
  	}
  
  	time = (data[0] << 16) | data[1];

  	rtc_time64_to_tm(time, &alrm->time);

  
  	ret = wm831x_reg_read(wm831x_rtc->wm831x, WM831X_RTC_CONTROL);
  	if (ret < 0) {
  		dev_err(dev, "Failed to read RTC control: %d
  ", ret);
  		return ret;
  	}
  
  	if (ret & WM831X_RTC_ALM_ENA)
  		alrm->enabled = 1;
  	else
  		alrm->enabled = 0;
  
  	return 0;
  }
  
  static int wm831x_rtc_stop_alarm(struct wm831x_rtc *wm831x_rtc)
  {
  	wm831x_rtc->alarm_enabled = 0;
  
  	return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
  			       WM831X_RTC_ALM_ENA, 0);
  }
  
  static int wm831x_rtc_start_alarm(struct wm831x_rtc *wm831x_rtc)
  {
  	wm831x_rtc->alarm_enabled = 1;
  
  	return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
  			       WM831X_RTC_ALM_ENA, WM831X_RTC_ALM_ENA);
  }
  
  static int wm831x_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
  	struct wm831x *wm831x = wm831x_rtc->wm831x;
  	int ret;
  	unsigned long time;

  	time = rtc_tm_to_time64(&alrm->time);

  
  	ret = wm831x_rtc_stop_alarm(wm831x_rtc);
  	if (ret < 0) {
  		dev_err(dev, "Failed to stop alarm: %d
  ", ret);
  		return ret;
  	}
  
  	ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_1,
  			       (time >> 16) & 0xffff);
  	if (ret < 0) {
  		dev_err(dev, "Failed to write ALARM_1: %d
  ", ret);
  		return ret;
  	}
  
  	ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_2, time & 0xffff);
  	if (ret < 0) {
  		dev_err(dev, "Failed to write ALARM_2: %d
  ", ret);
  		return ret;
  	}
  
  	if (alrm->enabled) {
  		ret = wm831x_rtc_start_alarm(wm831x_rtc);
  		if (ret < 0) {
  			dev_err(dev, "Failed to start alarm: %d
  ", ret);
  			return ret;
  		}
  	}
  
  	return 0;
  }
  
  static int wm831x_rtc_alarm_irq_enable(struct device *dev,
  				       unsigned int enabled)
  {
  	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
  
  	if (enabled)
  		return wm831x_rtc_start_alarm(wm831x_rtc);
  	else
  		return wm831x_rtc_stop_alarm(wm831x_rtc);
  }

  static irqreturn_t wm831x_alm_irq(int irq, void *data)
  {
  	struct wm831x_rtc *wm831x_rtc = data;
  
  	rtc_update_irq(wm831x_rtc->rtc, 1, RTC_IRQF | RTC_AF);
  
  	return IRQ_HANDLED;
  }

  static const struct rtc_class_ops wm831x_rtc_ops = {
  	.read_time = wm831x_rtc_readtime,

  	.set_time = wm831x_rtc_settime,

  	.read_alarm = wm831x_rtc_readalarm,
  	.set_alarm = wm831x_rtc_setalarm,
  	.alarm_irq_enable = wm831x_rtc_alarm_irq_enable,

  };
  
  #ifdef CONFIG_PM
  /* Turn off the alarm if it should not be a wake source. */
  static int wm831x_rtc_suspend(struct device *dev)
  {

  	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);

  	int ret, enable;

  	if (wm831x_rtc->alarm_enabled && device_may_wakeup(dev))

  		enable = WM831X_RTC_ALM_ENA;
  	else
  		enable = 0;
  
  	ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
  			      WM831X_RTC_ALM_ENA, enable);
  	if (ret != 0)

  		dev_err(dev, "Failed to update RTC alarm: %d
  ", ret);

  
  	return 0;
  }
  
  /* Enable the alarm if it should be enabled (in case it was disabled to
   * prevent use as a wake source).
   */
  static int wm831x_rtc_resume(struct device *dev)
  {

  	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);

  	int ret;
  
  	if (wm831x_rtc->alarm_enabled) {
  		ret = wm831x_rtc_start_alarm(wm831x_rtc);
  		if (ret != 0)

  			dev_err(dev, "Failed to restart RTC alarm: %d
  ", ret);

  	}
  
  	return 0;
  }
  
  /* Unconditionally disable the alarm */
  static int wm831x_rtc_freeze(struct device *dev)
  {

  	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);

  	int ret;
  
  	ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
  			      WM831X_RTC_ALM_ENA, 0);
  	if (ret != 0)

  		dev_err(dev, "Failed to stop RTC alarm: %d
  ", ret);

  
  	return 0;
  }
  #else
  #define wm831x_rtc_suspend NULL
  #define wm831x_rtc_resume NULL
  #define wm831x_rtc_freeze NULL
  #endif
  
  static int wm831x_rtc_probe(struct platform_device *pdev)
  {
  	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
  	struct wm831x_rtc *wm831x_rtc;

  	int alm_irq = wm831x_irq(wm831x, platform_get_irq_byname(pdev, "ALM"));

  	int ret = 0;

  	wm831x_rtc = devm_kzalloc(&pdev->dev, sizeof(*wm831x_rtc), GFP_KERNEL);

  	if (wm831x_rtc == NULL)
  		return -ENOMEM;
  
  	platform_set_drvdata(pdev, wm831x_rtc);
  	wm831x_rtc->wm831x = wm831x;
  
  	ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "Failed to read RTC control: %d
  ", ret);

  		return ret;

  	}
  	if (ret & WM831X_RTC_ALM_ENA)
  		wm831x_rtc->alarm_enabled = 1;
  
  	device_init_wakeup(&pdev->dev, 1);

  	wm831x_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
  	if (IS_ERR(wm831x_rtc->rtc))
  		return PTR_ERR(wm831x_rtc->rtc);
  
  	wm831x_rtc->rtc->ops = &wm831x_rtc_ops;
  	wm831x_rtc->rtc->range_max = U32_MAX;
  
  	ret = rtc_register_device(wm831x_rtc->rtc);
  	if (ret)
  		return ret;

  	ret = devm_request_threaded_irq(&pdev->dev, alm_irq, NULL,
  				wm831x_alm_irq,

  				IRQF_TRIGGER_RISING | IRQF_ONESHOT,
  				"RTC alarm",

  				wm831x_rtc);

  	if (ret != 0) {
  		dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d
  ",
  			alm_irq, ret);
  	}

  	wm831x_rtc_add_randomness(wm831x);

  	return 0;

  }

  static const struct dev_pm_ops wm831x_rtc_pm_ops = {

  	.suspend = wm831x_rtc_suspend,
  	.resume = wm831x_rtc_resume,
  
  	.freeze = wm831x_rtc_freeze,
  	.thaw = wm831x_rtc_resume,
  	.restore = wm831x_rtc_resume,
  
  	.poweroff = wm831x_rtc_suspend,
  };
  
  static struct platform_driver wm831x_rtc_driver = {
  	.probe = wm831x_rtc_probe,

  	.driver = {
  		.name = "wm831x-rtc",
  		.pm = &wm831x_rtc_pm_ops,
  	},
  };

  module_platform_driver(wm831x_rtc_driver);

  
  MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
  MODULE_DESCRIPTION("RTC driver for the WM831x series PMICs");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:wm831x-rtc");