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kernel/linux-imx6_3.14.28/drivers/rtc/rtc-ds1216.c 4.05 KB
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  /*
   * Dallas DS1216 RTC driver
   *
   * Copyright (c) 2007 Thomas Bogendoerfer
   *
   */
  
  #include <linux/module.h>
  #include <linux/rtc.h>
  #include <linux/platform_device.h>
  #include <linux/bcd.h>
  #include <linux/slab.h>
  
  #define DRV_VERSION "0.2"
  
  struct ds1216_regs {
  	u8 tsec;
  	u8 sec;
  	u8 min;
  	u8 hour;
  	u8 wday;
  	u8 mday;
  	u8 month;
  	u8 year;
  };
  
  #define DS1216_HOUR_1224	(1 << 7)
  #define DS1216_HOUR_AMPM	(1 << 5)
  
  struct ds1216_priv {
  	struct rtc_device *rtc;
  	void __iomem *ioaddr;
  };
  
  static const u8 magic[] = {
  	0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c
  };
  
  /*
   * Read the 64 bit we'd like to have - It a series
   * of 64 bits showing up in the LSB of the base register.
   *
   */
  static void ds1216_read(u8 __iomem *ioaddr, u8 *buf)
  {
  	unsigned char c;
  	int i, j;
  
  	for (i = 0; i < 8; i++) {
  		c = 0;
  		for (j = 0; j < 8; j++)
  			c |= (readb(ioaddr) & 0x1) << j;
  		buf[i] = c;
  	}
  }
  
  static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf)
  {
  	unsigned char c;
  	int i, j;
  
  	for (i = 0; i < 8; i++) {
  		c = buf[i];
  		for (j = 0; j < 8; j++) {
  			writeb(c, ioaddr);
  			c = c >> 1;
  		}
  	}
  }
  
  static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr)
  {
  	/* Reset magic pointer */
  	readb(ioaddr);
  	/* Write 64 bit magic to DS1216 */
  	ds1216_write(ioaddr, magic);
  }
  
  static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct ds1216_priv *priv = platform_get_drvdata(pdev);
  	struct ds1216_regs regs;
  
  	ds1216_switch_ds_to_clock(priv->ioaddr);
  	ds1216_read(priv->ioaddr, (u8 *)&regs);
  
  	tm->tm_sec = bcd2bin(regs.sec);
  	tm->tm_min = bcd2bin(regs.min);
  	if (regs.hour & DS1216_HOUR_1224) {
  		/* AM/PM mode */
  		tm->tm_hour = bcd2bin(regs.hour & 0x1f);
  		if (regs.hour & DS1216_HOUR_AMPM)
  			tm->tm_hour += 12;
  	} else
  		tm->tm_hour = bcd2bin(regs.hour & 0x3f);
  	tm->tm_wday = (regs.wday & 7) - 1;
  	tm->tm_mday = bcd2bin(regs.mday & 0x3f);
  	tm->tm_mon = bcd2bin(regs.month & 0x1f);
  	tm->tm_year = bcd2bin(regs.year);
  	if (tm->tm_year < 70)
  		tm->tm_year += 100;
  
  	return rtc_valid_tm(tm);
  }
  
  static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct ds1216_priv *priv = platform_get_drvdata(pdev);
  	struct ds1216_regs regs;
  
  	ds1216_switch_ds_to_clock(priv->ioaddr);
  	ds1216_read(priv->ioaddr, (u8 *)&regs);
  
  	regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
  	regs.sec = bin2bcd(tm->tm_sec);
  	regs.min = bin2bcd(tm->tm_min);
  	regs.hour &= DS1216_HOUR_1224;
  	if (regs.hour && tm->tm_hour > 12) {
  		regs.hour |= DS1216_HOUR_AMPM;
  		tm->tm_hour -= 12;
  	}
  	regs.hour |= bin2bcd(tm->tm_hour);
  	regs.wday &= ~7;
  	regs.wday |= tm->tm_wday;
  	regs.mday = bin2bcd(tm->tm_mday);
  	regs.month = bin2bcd(tm->tm_mon);
  	regs.year = bin2bcd(tm->tm_year % 100);
  
  	ds1216_switch_ds_to_clock(priv->ioaddr);
  	ds1216_write(priv->ioaddr, (u8 *)&regs);
  	return 0;
  }
  
  static const struct rtc_class_ops ds1216_rtc_ops = {
  	.read_time	= ds1216_rtc_read_time,
  	.set_time	= ds1216_rtc_set_time,
  };
  
  static int __init ds1216_rtc_probe(struct platform_device *pdev)
  {
  	struct resource *res;
  	struct ds1216_priv *priv;
  	u8 dummy[8];
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res)
  		return -ENODEV;
  	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;
  
  	platform_set_drvdata(pdev, priv);
  
  	priv->ioaddr = devm_ioremap_resource(&pdev->dev, res);
  	if (IS_ERR(priv->ioaddr))
  		return PTR_ERR(priv->ioaddr);
  
  	priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216",
  					&ds1216_rtc_ops, THIS_MODULE);
  	if (IS_ERR(priv->rtc))
  		return PTR_ERR(priv->rtc);
  
  	/* dummy read to get clock into a known state */
  	ds1216_read(priv->ioaddr, dummy);
  	return 0;
  }
  
  static struct platform_driver ds1216_rtc_platform_driver = {
  	.driver		= {
  		.name	= "rtc-ds1216",
  		.owner	= THIS_MODULE,
  	},
  };
  
  module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);
  
  MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
  MODULE_DESCRIPTION("DS1216 RTC driver");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(DRV_VERSION);
  MODULE_ALIAS("platform:rtc-ds1216");