/*
   * SiRFSoC Real Time Clock interface for Linux
   *
   * Copyright (c) 2013 Cambridge Silicon Radio Limited, a CSR plc group company.
   *
   * Licensed under GPLv2 or later.
   */
  
  #include <linux/module.h>
  #include <linux/err.h>
  #include <linux/rtc.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  #include <linux/io.h>
  #include <linux/of.h>
  #include <linux/rtc/sirfsoc_rtciobrg.h>
  
  
  #define RTC_CN			0x00
  #define RTC_ALARM0		0x04
  #define RTC_ALARM1		0x18
  #define RTC_STATUS		0x08
  #define RTC_SW_VALUE            0x40
  #define SIRFSOC_RTC_AL1E	(1<<6)
  #define SIRFSOC_RTC_AL1		(1<<4)
  #define SIRFSOC_RTC_HZE		(1<<3)
  #define SIRFSOC_RTC_AL0E	(1<<2)
  #define SIRFSOC_RTC_HZ		(1<<1)
  #define SIRFSOC_RTC_AL0		(1<<0)
  #define RTC_DIV			0x0c
  #define RTC_DEEP_CTRL		0x14
  #define RTC_CLOCK_SWITCH	0x1c
  #define SIRFSOC_RTC_CLK		0x03	/* others are reserved */
  
  /* Refer to RTC DIV switch */
  #define RTC_HZ			16
  
  /* This macro is also defined in arch/arm/plat-sirfsoc/cpu.c */
  #define RTC_SHIFT		4
  
  #define INTR_SYSRTC_CN		0x48
  
  struct sirfsoc_rtc_drv {
  	struct rtc_device	*rtc;
  	u32			rtc_base;
  	u32			irq;
  	unsigned		irq_wake;
  	/* Overflow for every 8 years extra time */
  	u32			overflow_rtc;
  #ifdef CONFIG_PM
  	u32		saved_counter;
  	u32		saved_overflow_rtc;
  #endif
  };
  
  static int sirfsoc_rtc_read_alarm(struct device *dev,
  		struct rtc_wkalrm *alrm)
  {
  	unsigned long rtc_alarm, rtc_count;
  	struct sirfsoc_rtc_drv *rtcdrv;
  
  	rtcdrv = dev_get_drvdata(dev);
  
  	local_irq_disable();
  
  	rtc_count = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN);
  
  	rtc_alarm = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_ALARM0);
  	memset(alrm, 0, sizeof(struct rtc_wkalrm));
  
  	/*
  	 * assume alarm interval not beyond one round counter overflow_rtc:
  	 * 0->0xffffffff
  	 */
  	/* if alarm is in next overflow cycle */
  	if (rtc_count > rtc_alarm)
  		rtc_time_to_tm((rtcdrv->overflow_rtc + 1)
  				<< (BITS_PER_LONG - RTC_SHIFT)
  				| rtc_alarm >> RTC_SHIFT, &(alrm->time));
  	else
  		rtc_time_to_tm(rtcdrv->overflow_rtc
  				<< (BITS_PER_LONG - RTC_SHIFT)
  				| rtc_alarm >> RTC_SHIFT, &(alrm->time));
  	if (sirfsoc_rtc_iobrg_readl(
  			rtcdrv->rtc_base + RTC_STATUS) & SIRFSOC_RTC_AL0E)
  		alrm->enabled = 1;
  	local_irq_enable();
  
  	return 0;
  }
  
  static int sirfsoc_rtc_set_alarm(struct device *dev,
  		struct rtc_wkalrm *alrm)
  {
  	unsigned long rtc_status_reg, rtc_alarm;
  	struct sirfsoc_rtc_drv *rtcdrv;
  	rtcdrv = dev_get_drvdata(dev);
  
  	if (alrm->enabled) {
  		rtc_tm_to_time(&(alrm->time), &rtc_alarm);
  
  		local_irq_disable();
  
  		rtc_status_reg = sirfsoc_rtc_iobrg_readl(
  				rtcdrv->rtc_base + RTC_STATUS);
  		if (rtc_status_reg & SIRFSOC_RTC_AL0E) {
  			/*
  			 * An ongoing alarm in progress - ingore it and not
  			 * to return EBUSY
  			 */
  			dev_info(dev, "An old alarm was set, will be replaced by a new one
  ");
  		}
  
  		sirfsoc_rtc_iobrg_writel(
  			rtc_alarm << RTC_SHIFT, rtcdrv->rtc_base + RTC_ALARM0);
  		rtc_status_reg &= ~0x07; /* mask out the lower status bits */
  		/*
  		 * This bit RTC_AL sets it as a wake-up source for Sleep Mode
  		 * Writing 1 into this bit will clear it
  		 */
  		rtc_status_reg |= SIRFSOC_RTC_AL0;
  		/* enable the RTC alarm interrupt */
  		rtc_status_reg |= SIRFSOC_RTC_AL0E;
  		sirfsoc_rtc_iobrg_writel(
  			rtc_status_reg, rtcdrv->rtc_base + RTC_STATUS);
  		local_irq_enable();
  	} else {
  		/*
  		 * if this function was called with enabled=0
  		 * then it could mean that the application is
  		 * trying to cancel an ongoing alarm
  		 */
  		local_irq_disable();
  
  		rtc_status_reg = sirfsoc_rtc_iobrg_readl(
  				rtcdrv->rtc_base + RTC_STATUS);
  		if (rtc_status_reg & SIRFSOC_RTC_AL0E) {
  			/* clear the RTC status register's alarm bit */
  			rtc_status_reg &= ~0x07;
  			/* write 1 into SIRFSOC_RTC_AL0 to force a clear */
  			rtc_status_reg |= (SIRFSOC_RTC_AL0);
  			/* Clear the Alarm enable bit */
  			rtc_status_reg &= ~(SIRFSOC_RTC_AL0E);
  
  			sirfsoc_rtc_iobrg_writel(rtc_status_reg,
  					rtcdrv->rtc_base + RTC_STATUS);
  		}
  
  		local_irq_enable();
  	}
  
  	return 0;
  }
  
  static int sirfsoc_rtc_read_time(struct device *dev,
  		struct rtc_time *tm)
  {
  	unsigned long tmp_rtc = 0;
  	struct sirfsoc_rtc_drv *rtcdrv;
  	rtcdrv = dev_get_drvdata(dev);
  	/*
  	 * This patch is taken from WinCE - Need to validate this for
  	 * correctness. To work around sirfsoc RTC counter double sync logic
  	 * fail, read several times to make sure get stable value.
  	 */
  	do {
  		tmp_rtc = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN);
  		cpu_relax();
  	} while (tmp_rtc != sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN));
  
  	rtc_time_to_tm(rtcdrv->overflow_rtc << (BITS_PER_LONG - RTC_SHIFT) |
  					tmp_rtc >> RTC_SHIFT, tm);
  	return 0;
  }
  
  static int sirfsoc_rtc_set_time(struct device *dev,
  		struct rtc_time *tm)
  {
  	unsigned long rtc_time;
  	struct sirfsoc_rtc_drv *rtcdrv;
  	rtcdrv = dev_get_drvdata(dev);
  
  	rtc_tm_to_time(tm, &rtc_time);
  
  	rtcdrv->overflow_rtc = rtc_time >> (BITS_PER_LONG - RTC_SHIFT);
  
  	sirfsoc_rtc_iobrg_writel(rtcdrv->overflow_rtc,
  			rtcdrv->rtc_base + RTC_SW_VALUE);
  	sirfsoc_rtc_iobrg_writel(
  			rtc_time << RTC_SHIFT, rtcdrv->rtc_base + RTC_CN);
  
  	return 0;
  }
  
  static int sirfsoc_rtc_ioctl(struct device *dev, unsigned int cmd,
  		unsigned long arg)
  {
  	switch (cmd) {
  	case RTC_PIE_ON:
  	case RTC_PIE_OFF:
  	case RTC_UIE_ON:
  	case RTC_UIE_OFF:
  	case RTC_AIE_ON:
  	case RTC_AIE_OFF:
  		return 0;
  
  	default:
  		return -ENOIOCTLCMD;
  	}
  }
  
  static const struct rtc_class_ops sirfsoc_rtc_ops = {
  	.read_time = sirfsoc_rtc_read_time,
  	.set_time = sirfsoc_rtc_set_time,
  	.read_alarm = sirfsoc_rtc_read_alarm,
  	.set_alarm = sirfsoc_rtc_set_alarm,
  	.ioctl = sirfsoc_rtc_ioctl
  };
  
  static irqreturn_t sirfsoc_rtc_irq_handler(int irq, void *pdata)
  {
  	struct sirfsoc_rtc_drv *rtcdrv = pdata;
  	unsigned long rtc_status_reg = 0x0;
  	unsigned long events = 0x0;
  
  	rtc_status_reg = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_STATUS);
  	/* this bit will be set ONLY if an alarm was active
  	 * and it expired NOW
  	 * So this is being used as an ASSERT
  	 */
  	if (rtc_status_reg & SIRFSOC_RTC_AL0) {
  		/*
  		 * clear the RTC status register's alarm bit
  		 * mask out the lower status bits
  		 */
  		rtc_status_reg &= ~0x07;
  		/* write 1 into SIRFSOC_RTC_AL0 to ACK the alarm interrupt */
  		rtc_status_reg |= (SIRFSOC_RTC_AL0);
  		/* Clear the Alarm enable bit */
  		rtc_status_reg &= ~(SIRFSOC_RTC_AL0E);
  	}
  	sirfsoc_rtc_iobrg_writel(rtc_status_reg, rtcdrv->rtc_base + RTC_STATUS);
  	/* this should wake up any apps polling/waiting on the read
  	 * after setting the alarm
  	 */
  	events |= RTC_IRQF | RTC_AF;
  	rtc_update_irq(rtcdrv->rtc, 1, events);
  
  	return IRQ_HANDLED;
  }
  
  static const struct of_device_id sirfsoc_rtc_of_match[] = {
  	{ .compatible = "sirf,prima2-sysrtc"},
  	{},
  };
  MODULE_DEVICE_TABLE(of, sirfsoc_rtc_of_match);
  
  static int sirfsoc_rtc_probe(struct platform_device *pdev)
  {
  	int err;
  	unsigned long rtc_div;
  	struct sirfsoc_rtc_drv *rtcdrv;
  	struct device_node *np = pdev->dev.of_node;
  
  	rtcdrv = devm_kzalloc(&pdev->dev,
  		sizeof(struct sirfsoc_rtc_drv), GFP_KERNEL);
  	if (rtcdrv == NULL) {
  		dev_err(&pdev->dev,
  			"%s: can't alloc mem for drv struct
  ",
  			pdev->name);
  		return -ENOMEM;
  	}
  
  	err = of_property_read_u32(np, "reg", &rtcdrv->rtc_base);
  	if (err) {
  		dev_err(&pdev->dev, "unable to find base address of rtc node in dtb
  ");
  		return err;
  	}
  
  	platform_set_drvdata(pdev, rtcdrv);
  
  	/* Register rtc alarm as a wakeup source */
  	device_init_wakeup(&pdev->dev, 1);
  
  	/*
  	 * Set SYS_RTC counter in RTC_HZ HZ Units
  	 * We are using 32K RTC crystal (32768 / RTC_HZ / 2) -1
  	 * If 16HZ, therefore RTC_DIV = 1023;
  	 */
  	rtc_div = ((32768 / RTC_HZ) / 2) - 1;
  	sirfsoc_rtc_iobrg_writel(rtc_div, rtcdrv->rtc_base + RTC_DIV);
  
  	rtcdrv->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
  			&sirfsoc_rtc_ops, THIS_MODULE);
  	if (IS_ERR(rtcdrv->rtc)) {
  		err = PTR_ERR(rtcdrv->rtc);
  		dev_err(&pdev->dev, "can't register RTC device
  ");
  		return err;
  	}
  
  	/* 0x3 -> RTC_CLK */
  	sirfsoc_rtc_iobrg_writel(SIRFSOC_RTC_CLK,
  			rtcdrv->rtc_base + RTC_CLOCK_SWITCH);
  
  	/* reset SYS RTC ALARM0 */
  	sirfsoc_rtc_iobrg_writel(0x0, rtcdrv->rtc_base + RTC_ALARM0);
  
  	/* reset SYS RTC ALARM1 */
  	sirfsoc_rtc_iobrg_writel(0x0, rtcdrv->rtc_base + RTC_ALARM1);
  
  	/* Restore RTC Overflow From Register After Command Reboot */
  	rtcdrv->overflow_rtc =
  		sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_SW_VALUE);
  
  	rtcdrv->irq = platform_get_irq(pdev, 0);
  	err = devm_request_irq(
  			&pdev->dev,
  			rtcdrv->irq,
  			sirfsoc_rtc_irq_handler,
  			IRQF_SHARED,
  			pdev->name,
  			rtcdrv);
  	if (err) {
  		dev_err(&pdev->dev, "Unable to register for the SiRF SOC RTC IRQ
  ");
  		return err;
  	}
  
  	return 0;
  }
  
  static int sirfsoc_rtc_remove(struct platform_device *pdev)
  {
  	device_init_wakeup(&pdev->dev, 0);
  
  	return 0;
  }
  
  #ifdef CONFIG_PM
  
  static int sirfsoc_rtc_suspend(struct device *dev)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct sirfsoc_rtc_drv *rtcdrv = platform_get_drvdata(pdev);
  	rtcdrv->overflow_rtc =
  		sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_SW_VALUE);
  
  	rtcdrv->saved_counter =
  		sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN);
  	rtcdrv->saved_overflow_rtc = rtcdrv->overflow_rtc;
  	if (device_may_wakeup(&pdev->dev) && !enable_irq_wake(rtcdrv->irq))
  		rtcdrv->irq_wake = 1;
  
  	return 0;
  }
  
  static int sirfsoc_rtc_freeze(struct device *dev)
  {
  	sirfsoc_rtc_suspend(dev);
  
  	return 0;
  }
  
  static int sirfsoc_rtc_thaw(struct device *dev)
  {
  	u32 tmp;
  	struct sirfsoc_rtc_drv *rtcdrv;
  	rtcdrv = dev_get_drvdata(dev);
  
  	/*
  	 * if resume from snapshot and the rtc power is losed,
  	 * restroe the rtc settings
  	 */
  	if (SIRFSOC_RTC_CLK != sirfsoc_rtc_iobrg_readl(
  			rtcdrv->rtc_base + RTC_CLOCK_SWITCH)) {
  		u32 rtc_div;
  		/* 0x3 -> RTC_CLK */
  		sirfsoc_rtc_iobrg_writel(SIRFSOC_RTC_CLK,
  			rtcdrv->rtc_base + RTC_CLOCK_SWITCH);
  		/*
  		 * Set SYS_RTC counter in RTC_HZ HZ Units
  		 * We are using 32K RTC crystal (32768 / RTC_HZ / 2) -1
  		 * If 16HZ, therefore RTC_DIV = 1023;
  		 */
  		rtc_div = ((32768 / RTC_HZ) / 2) - 1;
  
  		sirfsoc_rtc_iobrg_writel(rtc_div, rtcdrv->rtc_base + RTC_DIV);
  
  		/* reset SYS RTC ALARM0 */
  		sirfsoc_rtc_iobrg_writel(0x0, rtcdrv->rtc_base + RTC_ALARM0);
  
  		/* reset SYS RTC ALARM1 */
  		sirfsoc_rtc_iobrg_writel(0x0, rtcdrv->rtc_base + RTC_ALARM1);
  	}
  	rtcdrv->overflow_rtc = rtcdrv->saved_overflow_rtc;
  
  	/*
  	 * if current counter is small than previous,
  	 * it means overflow in sleep
  	 */
  	tmp = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN);
  	if (tmp <= rtcdrv->saved_counter)
  		rtcdrv->overflow_rtc++;
  	/*
  	 *PWRC Value Be Changed When Suspend, Restore Overflow
  	 * In Memory To Register
  	 */
  	sirfsoc_rtc_iobrg_writel(rtcdrv->overflow_rtc,
  			rtcdrv->rtc_base + RTC_SW_VALUE);
  
  	return 0;
  }
  
  static int sirfsoc_rtc_resume(struct device *dev)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct sirfsoc_rtc_drv *rtcdrv = platform_get_drvdata(pdev);
  	sirfsoc_rtc_thaw(dev);
  	if (device_may_wakeup(&pdev->dev) && rtcdrv->irq_wake) {
  		disable_irq_wake(rtcdrv->irq);
  		rtcdrv->irq_wake = 0;
  	}
  
  	return 0;
  }
  
  static int sirfsoc_rtc_restore(struct device *dev)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct sirfsoc_rtc_drv *rtcdrv = platform_get_drvdata(pdev);
  
  	if (device_may_wakeup(&pdev->dev) && rtcdrv->irq_wake) {
  		disable_irq_wake(rtcdrv->irq);
  		rtcdrv->irq_wake = 0;
  	}
  	return 0;
  }
  
  #else
  #define sirfsoc_rtc_suspend	NULL
  #define sirfsoc_rtc_resume	NULL
  #define sirfsoc_rtc_freeze	NULL
  #define sirfsoc_rtc_thaw	NULL
  #define sirfsoc_rtc_restore	NULL
  #endif
  
  static const struct dev_pm_ops sirfsoc_rtc_pm_ops = {
  	.suspend = sirfsoc_rtc_suspend,
  	.resume = sirfsoc_rtc_resume,
  	.freeze = sirfsoc_rtc_freeze,
  	.thaw = sirfsoc_rtc_thaw,
  	.restore = sirfsoc_rtc_restore,
  };
  
  static struct platform_driver sirfsoc_rtc_driver = {
  	.driver = {
  		.name = "sirfsoc-rtc",
  		.owner = THIS_MODULE,
  #ifdef CONFIG_PM
  		.pm = &sirfsoc_rtc_pm_ops,
  #endif
  		.of_match_table = sirfsoc_rtc_of_match,
  	},
  	.probe = sirfsoc_rtc_probe,
  	.remove = sirfsoc_rtc_remove,
  };
  module_platform_driver(sirfsoc_rtc_driver);
  
  MODULE_DESCRIPTION("SiRF SoC rtc driver");
  MODULE_AUTHOR("Xianglong Du <Xianglong.Du@csr.com>");
  MODULE_LICENSE("GPL v2");
  MODULE_ALIAS("platform:sirfsoc-rtc");