text: /*
   * drivers/rtc/rtc-pl031.c
   *
   * Real Time Clock interface for ARM AMBA PrimeCell 031 RTC
   *
   * Author: Deepak Saxena <dsaxena@plexity.net>
   *
   * Copyright 2006 (c) MontaVista Software, Inc.
   *
   * Author: Mian Yousaf Kaukab <mian.yousaf.kaukab@stericsson.com>
   * Copyright 2010 (c) ST-Ericsson AB
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  #include <linux/module.h>
  #include <linux/rtc.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/amba/bus.h>
  #include <linux/io.h>
  #include <linux/bcd.h>
  #include <linux/delay.h>
  #include <linux/version.h>
  #include <linux/slab.h>
  
  /*
   * Register definitions
   */
  #define	RTC_DR		0x00	/* Data read register */
  #define	RTC_MR		0x04	/* Match register */
  #define	RTC_LR		0x08	/* Data load register */
  #define	RTC_CR		0x0c	/* Control register */
  #define	RTC_IMSC	0x10	/* Interrupt mask and set register */
  #define	RTC_RIS		0x14	/* Raw interrupt status register */
  #define	RTC_MIS		0x18	/* Masked interrupt status register */
  #define	RTC_ICR		0x1c	/* Interrupt clear register */
  /* ST variants have additional timer functionality */
  #define RTC_TDR		0x20	/* Timer data read register */
  #define RTC_TLR		0x24	/* Timer data load register */
  #define RTC_TCR		0x28	/* Timer control register */
  #define RTC_YDR		0x30	/* Year data read register */
  #define RTC_YMR		0x34	/* Year match register */
  #define RTC_YLR		0x38	/* Year data load register */
  
  #define RTC_CR_CWEN	(1 << 26)	/* Clockwatch enable bit */
  
  #define RTC_TCR_EN	(1 << 1) /* Periodic timer enable bit */
  
  /* Common bit definitions for Interrupt status and control registers */
  #define RTC_BIT_AI	(1 << 0) /* Alarm interrupt bit */
  #define RTC_BIT_PI	(1 << 1) /* Periodic interrupt bit. ST variants only. */
  
  /* Common bit definations for ST v2 for reading/writing time */
  #define RTC_SEC_SHIFT 0
  #define RTC_SEC_MASK (0x3F << RTC_SEC_SHIFT) /* Second [0-59] */
  #define RTC_MIN_SHIFT 6
  #define RTC_MIN_MASK (0x3F << RTC_MIN_SHIFT) /* Minute [0-59] */
  #define RTC_HOUR_SHIFT 12
  #define RTC_HOUR_MASK (0x1F << RTC_HOUR_SHIFT) /* Hour [0-23] */
  #define RTC_WDAY_SHIFT 17
  #define RTC_WDAY_MASK (0x7 << RTC_WDAY_SHIFT) /* Day of Week [1-7] 1=Sunday */
  #define RTC_MDAY_SHIFT 20
  #define RTC_MDAY_MASK (0x1F << RTC_MDAY_SHIFT) /* Day of Month [1-31] */
  #define RTC_MON_SHIFT 25
  #define RTC_MON_MASK (0xF << RTC_MON_SHIFT) /* Month [1-12] 1=January */
  
  #define RTC_TIMER_FREQ 32768
  
  struct pl031_local {
  	struct rtc_device *rtc;
  	void __iomem *base;
  	u8 hw_designer;
  	u8 hw_revision:4;
  };
  
  static int pl031_alarm_irq_enable(struct device *dev,
  	unsigned int enabled)
  {
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  	unsigned long imsc;
  
  	/* Clear any pending alarm interrupts. */
  	writel(RTC_BIT_AI, ldata->base + RTC_ICR);
  
  	imsc = readl(ldata->base + RTC_IMSC);
  
  	if (enabled == 1)
  		writel(imsc | RTC_BIT_AI, ldata->base + RTC_IMSC);
  	else
  		writel(imsc & ~RTC_BIT_AI, ldata->base + RTC_IMSC);
  
  	return 0;
  }
  
  /*
   * Convert Gregorian date to ST v2 RTC format.
   */
  static int pl031_stv2_tm_to_time(struct device *dev,
  				 struct rtc_time *tm, unsigned long *st_time,
  	unsigned long *bcd_year)
  {
  	int year = tm->tm_year + 1900;
  	int wday = tm->tm_wday;
  
  	/* wday masking is not working in hardware so wday must be valid */
  	if (wday < -1 || wday > 6) {
  		dev_err(dev, "invalid wday value %d\n", tm->tm_wday);
  		return -EINVAL;
  	} else if (wday == -1) {
  		/* wday is not provided, calculate it here */
  		unsigned long time;
  		struct rtc_time calc_tm;
  
  		rtc_tm_to_time(tm, &time);
  		rtc_time_to_tm(time, &calc_tm);
  		wday = calc_tm.tm_wday;
  	}
  
  	*bcd_year = (bin2bcd(year % 100) | bin2bcd(year / 100) << 8);
  
  	*st_time = ((tm->tm_mon + 1) << RTC_MON_SHIFT)
  			|	(tm->tm_mday << RTC_MDAY_SHIFT)
  			|	((wday + 1) << RTC_WDAY_SHIFT)
  			|	(tm->tm_hour << RTC_HOUR_SHIFT)
  			|	(tm->tm_min << RTC_MIN_SHIFT)
  			|	(tm->tm_sec << RTC_SEC_SHIFT);
  
  	return 0;
  }
  
  /*
   * Convert ST v2 RTC format to Gregorian date.
   */
  static int pl031_stv2_time_to_tm(unsigned long st_time, unsigned long bcd_year,
  	struct rtc_time *tm)
  {
  	tm->tm_year = bcd2bin(bcd_year) + (bcd2bin(bcd_year >> 8) * 100);
  	tm->tm_mon  = ((st_time & RTC_MON_MASK) >> RTC_MON_SHIFT) - 1;
  	tm->tm_mday = ((st_time & RTC_MDAY_MASK) >> RTC_MDAY_SHIFT);
  	tm->tm_wday = ((st_time & RTC_WDAY_MASK) >> RTC_WDAY_SHIFT) - 1;
  	tm->tm_hour = ((st_time & RTC_HOUR_MASK) >> RTC_HOUR_SHIFT);
  	tm->tm_min  = ((st_time & RTC_MIN_MASK) >> RTC_MIN_SHIFT);
  	tm->tm_sec  = ((st_time & RTC_SEC_MASK) >> RTC_SEC_SHIFT);
  
  	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
  	tm->tm_year -= 1900;
  
  	return 0;
  }
  
  static int pl031_stv2_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  
  	pl031_stv2_time_to_tm(readl(ldata->base + RTC_DR),
  			readl(ldata->base + RTC_YDR), tm);
  
  	return 0;
  }
  
  static int pl031_stv2_set_time(struct device *dev, struct rtc_time *tm)
  {
  	unsigned long time;
  	unsigned long bcd_year;
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  	int ret;
  
  	ret = pl031_stv2_tm_to_time(dev, tm, &time, &bcd_year);
  	if (ret == 0) {
  		writel(bcd_year, ldata->base + RTC_YLR);
  		writel(time, ldata->base + RTC_LR);
  	}
  
  	return ret;
  }
  
  static int pl031_stv2_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
  {
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  	int ret;
  
  	ret = pl031_stv2_time_to_tm(readl(ldata->base + RTC_MR),
  			readl(ldata->base + RTC_YMR), &alarm->time);
  
  	alarm->pending = readl(ldata->base + RTC_RIS) & RTC_BIT_AI;
  	alarm->enabled = readl(ldata->base + RTC_IMSC) & RTC_BIT_AI;
  
  	return ret;
  }
  
  static int pl031_stv2_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
  {
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  	unsigned long time;
  	unsigned long bcd_year;
  	int ret;
  
  	/* At the moment, we can only deal with non-wildcarded alarm times. */
  	ret = rtc_valid_tm(&alarm->time);
  	if (ret == 0) {
  		ret = pl031_stv2_tm_to_time(dev, &alarm->time,
  					    &time, &bcd_year);
  		if (ret == 0) {
  			writel(bcd_year, ldata->base + RTC_YMR);
  			writel(time, ldata->base + RTC_MR);
  
  			pl031_alarm_irq_enable(dev, alarm->enabled);
  		}
  	}
  
  	return ret;
  }
  
  static irqreturn_t pl031_interrupt(int irq, void *dev_id)
  {
  	struct pl031_local *ldata = dev_id;
  	unsigned long rtcmis;
  	unsigned long events = 0;
  
  	rtcmis = readl(ldata->base + RTC_MIS);
  	if (rtcmis) {
  		writel(rtcmis, ldata->base + RTC_ICR);
  
  		if (rtcmis & RTC_BIT_AI)
  			events |= (RTC_AF | RTC_IRQF);
  
  		/* Timer interrupt is only available in ST variants */
  		if ((rtcmis & RTC_BIT_PI) &&
  			(ldata->hw_designer == AMBA_VENDOR_ST))
  			events |= (RTC_PF | RTC_IRQF);
  
  		rtc_update_irq(ldata->rtc, 1, events);
  
  		return IRQ_HANDLED;
  	}
  
  	return IRQ_NONE;
  }
  
  static int pl031_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  
  	rtc_time_to_tm(readl(ldata->base + RTC_DR), tm);
  
  	return 0;
  }
  
  static int pl031_set_time(struct device *dev, struct rtc_time *tm)
  {
  	unsigned long time;
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  	int ret;
  
  	ret = rtc_tm_to_time(tm, &time);
  
  	if (ret == 0)
  		writel(time, ldata->base + RTC_LR);
  
  	return ret;
  }
  
  static int pl031_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
  {
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  
  	rtc_time_to_tm(readl(ldata->base + RTC_MR), &alarm->time);
  
  	alarm->pending = readl(ldata->base + RTC_RIS) & RTC_BIT_AI;
  	alarm->enabled = readl(ldata->base + RTC_IMSC) & RTC_BIT_AI;
  
  	return 0;
  }
  
  static int pl031_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
  {
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  	unsigned long time;
  	int ret;
  
  	/* At the moment, we can only deal with non-wildcarded alarm times. */
  	ret = rtc_valid_tm(&alarm->time);
  	if (ret == 0) {
  		ret = rtc_tm_to_time(&alarm->time, &time);
  		if (ret == 0) {
  			writel(time, ldata->base + RTC_MR);
  			pl031_alarm_irq_enable(dev, alarm->enabled);
  		}
  	}
  
  	return ret;
  }
  
  /* Periodic interrupt is only available in ST variants. */
  static int pl031_irq_set_state(struct device *dev, int enabled)
  {
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  
  	if (enabled == 1) {
  		/* Clear any pending timer interrupt. */
  		writel(RTC_BIT_PI, ldata->base + RTC_ICR);
  
  		writel(readl(ldata->base + RTC_IMSC) | RTC_BIT_PI,
  			ldata->base + RTC_IMSC);
  
  		/* Now start the timer */
  		writel(readl(ldata->base + RTC_TCR) | RTC_TCR_EN,
  			ldata->base + RTC_TCR);
  
  	} else {
  		writel(readl(ldata->base + RTC_IMSC) & (~RTC_BIT_PI),
  			ldata->base + RTC_IMSC);
  
  		/* Also stop the timer */
  		writel(readl(ldata->base + RTC_TCR) & (~RTC_TCR_EN),
  			ldata->base + RTC_TCR);
  	}
  	/* Wait at least 1 RTC32 clock cycle to ensure next access
  	 * to RTC_TCR will succeed.
  	 */
  	udelay(40);
  
  	return 0;
  }
  
  static int pl031_irq_set_freq(struct device *dev, int freq)
  {
  	struct pl031_local *ldata = dev_get_drvdata(dev);
  
  	/* Cant set timer if it is already enabled */
  	if (readl(ldata->base + RTC_TCR) & RTC_TCR_EN) {
  		dev_err(dev, "can't change frequency while timer enabled\n");
  		return -EINVAL;
  	}
  
  	/* If self start bit in RTC_TCR is set timer will start here,
  	 * but we never set that bit. Instead we start the timer when
  	 * set_state is called with enabled == 1.
  	 */
  	writel(RTC_TIMER_FREQ / freq, ldata->base + RTC_TLR);
  
  	return 0;
  }
  
  static int pl031_remove(struct amba_device *adev)
  {
  	struct pl031_local *ldata = dev_get_drvdata(&adev->dev);
  
  	amba_set_drvdata(adev, NULL);
  	free_irq(adev->irq[0], ldata->rtc);
  	rtc_device_unregister(ldata->rtc);
  	iounmap(ldata->base);
  	kfree(ldata);
  	amba_release_regions(adev);
  
  	return 0;
  }
  
  static int pl031_probe(struct amba_device *adev, struct amba_id *id)
  {
  	int ret;
  	struct pl031_local *ldata;
  	struct rtc_class_ops *ops = id->data;
  
  	ret = amba_request_regions(adev, NULL);
  	if (ret)
  		goto err_req;
  
  	ldata = kzalloc(sizeof(struct pl031_local), GFP_KERNEL);
  	if (!ldata) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	ldata->base = ioremap(adev->res.start, resource_size(&adev->res));
  
  	if (!ldata->base) {
  		ret = -ENOMEM;
  		goto out_no_remap;
  	}
  
  	amba_set_drvdata(adev, ldata);
  
  	ldata->hw_designer = amba_manf(adev);
  	ldata->hw_revision = amba_rev(adev);
  
  	dev_dbg(&adev->dev, "designer ID = 0x%02x\n", ldata->hw_designer);
  	dev_dbg(&adev->dev, "revision = 0x%01x\n", ldata->hw_revision);
  
  	/* Enable the clockwatch on ST Variants */
  	if ((ldata->hw_designer == AMBA_VENDOR_ST) &&
  	    (ldata->hw_revision > 1))
  		writel(readl(ldata->base + RTC_CR) | RTC_CR_CWEN,
  		       ldata->base + RTC_CR);
  
  	ldata->rtc = rtc_device_register("pl031", &adev->dev, ops,
  					THIS_MODULE);
  	if (IS_ERR(ldata->rtc)) {
  		ret = PTR_ERR(ldata->rtc);
  		goto out_no_rtc;
  	}
  
  	if (request_irq(adev->irq[0], pl031_interrupt,
  			IRQF_DISABLED | IRQF_SHARED, "rtc-pl031", ldata)) {
  		ret = -EIO;
  		goto out_no_irq;
  	}
  
  	return 0;
  
  out_no_irq:
  	rtc_device_unregister(ldata->rtc);
  out_no_rtc:
  	iounmap(ldata->base);
  	amba_set_drvdata(adev, NULL);
  out_no_remap:
  	kfree(ldata);
  out:
  	amba_release_regions(adev);
  err_req:
  
  	return ret;
  }
  
  /* Operations for the original ARM version */
  static struct rtc_class_ops arm_pl031_ops = {
  	.read_time = pl031_read_time,
  	.set_time = pl031_set_time,
  	.read_alarm = pl031_read_alarm,
  	.set_alarm = pl031_set_alarm,
  	.alarm_irq_enable = pl031_alarm_irq_enable,
  };
  
  /* The First ST derivative */
  static struct rtc_class_ops stv1_pl031_ops = {
  	.read_time = pl031_read_time,
  	.set_time = pl031_set_time,
  	.read_alarm = pl031_read_alarm,
  	.set_alarm = pl031_set_alarm,
  	.alarm_irq_enable = pl031_alarm_irq_enable,
  	.irq_set_state = pl031_irq_set_state,
  	.irq_set_freq = pl031_irq_set_freq,
  };
  
  /* And the second ST derivative */
  static struct rtc_class_ops stv2_pl031_ops = {
  	.read_time = pl031_stv2_read_time,
  	.set_time = pl031_stv2_set_time,
  	.read_alarm = pl031_stv2_read_alarm,
  	.set_alarm = pl031_stv2_set_alarm,
  	.alarm_irq_enable = pl031_alarm_irq_enable,
  	.irq_set_state = pl031_irq_set_state,
  	.irq_set_freq = pl031_irq_set_freq,
  };
  
  static struct amba_id pl031_ids[] __initdata = {
  	{
  		.id = 0x00041031,
  		.mask = 0x000fffff,
  		.data = &arm_pl031_ops,
  	},
  	/* ST Micro variants */
  	{
  		.id = 0x00180031,
  		.mask = 0x00ffffff,
  		.data = &stv1_pl031_ops,
  	},
  	{
  		.id = 0x00280031,
  		.mask = 0x00ffffff,
  		.data = &stv2_pl031_ops,
  	},
  	{0, 0},
  };
  
  static struct amba_driver pl031_driver = {
  	.drv = {
  		.name = "rtc-pl031",
  	},
  	.id_table = pl031_ids,
  	.probe = pl031_probe,
  	.remove = pl031_remove,
  };
  
  static int __init pl031_init(void)
  {
  	return amba_driver_register(&pl031_driver);
  }
  
  static void __exit pl031_exit(void)
  {
  	amba_driver_unregister(&pl031_driver);
  }
  
  module_init(pl031_init);
  module_exit(pl031_exit);
  
  MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net");
  MODULE_DESCRIPTION("ARM AMBA PL031 RTC Driver");
  MODULE_LICENSE("GPL");
  