drivers/rtc/rtc-ds1216.c

   1 /*
   2  * Dallas DS1216 RTC driver
   3  *
   4  * Copyright (c) 2007 Thomas Bogendoerfer
   5  *
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/rtc.h>
  10 #include <linux/platform_device.h>
  11 #include <linux/bcd.h>
  12 #include <linux/slab.h>
  13
  14 #define DRV_VERSION "0.2"
  15
  16 struct ds1216_regs {
  17         u8 tsec;
  18         u8 sec;
  19         u8 min;
  20         u8 hour;
  21         u8 wday;
  22         u8 mday;
  23         u8 month;
  24         u8 year;
  25 };
  26
  27 #define DS1216_HOUR_1224        (1 << 7)
  28 #define DS1216_HOUR_AMPM        (1 << 5)
  29
  30 struct ds1216_priv {
  31         struct rtc_device *rtc;
  32         void __iomem *ioaddr;
  33 };
  34
  35 static const u8 magic[] = {
  36         0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c
  37 };
  38
  39 /*
  40  * Read the 64 bit we'd like to have - It a series
  41  * of 64 bits showing up in the LSB of the base register.
  42  *
  43  */
  44 static void ds1216_read(u8 __iomem *ioaddr, u8 *buf)
  45 {
  46         unsigned char c;
  47         int i, j;
  48
  49         for (i = 0; i < 8; i++) {
  50                 c = 0;
  51                 for (j = 0; j < 8; j++)
  52                         c |= (readb(ioaddr) & 0x1) << j;
  53                 buf[i] = c;
  54         }
  55 }
  56
  57 static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf)
  58 {
  59         unsigned char c;
  60         int i, j;
  61
  62         for (i = 0; i < 8; i++) {
  63                 c = buf[i];
  64                 for (j = 0; j < 8; j++) {
  65                         writeb(c, ioaddr);
  66                         c = c >> 1;
  67                 }
  68         }
  69 }
  70
  71 static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr)
  72 {
  73         /* Reset magic pointer */
  74         readb(ioaddr);
  75         /* Write 64 bit magic to DS1216 */
  76         ds1216_write(ioaddr, magic);
  77 }
  78
  79 static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
  80 {
  81         struct platform_device *pdev = to_platform_device(dev);
  82         struct ds1216_priv *priv = platform_get_drvdata(pdev);
  83         struct ds1216_regs regs;
  84
  85         ds1216_switch_ds_to_clock(priv->ioaddr);
  86         ds1216_read(priv->ioaddr, (u8 *)&regs);
  87
  88         tm->tm_sec = bcd2bin(regs.sec);
  89         tm->tm_min = bcd2bin(regs.min);
  90         if (regs.hour & DS1216_HOUR_1224) {
  91                 /* AM/PM mode */
  92                 tm->tm_hour = bcd2bin(regs.hour & 0x1f);
  93                 if (regs.hour & DS1216_HOUR_AMPM)
  94                         tm->tm_hour += 12;
  95         } else
  96                 tm->tm_hour = bcd2bin(regs.hour & 0x3f);
  97         tm->tm_wday = (regs.wday & 7) - 1;
  98         tm->tm_mday = bcd2bin(regs.mday & 0x3f);
  99         tm->tm_mon = bcd2bin(regs.month & 0x1f);
 100         tm->tm_year = bcd2bin(regs.year);
 101         if (tm->tm_year < 70)
 102                 tm->tm_year += 100;
 103
 104         return rtc_valid_tm(tm);
 105 }
 106
 107 static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
 108 {
 109         struct platform_device *pdev = to_platform_device(dev);
 110         struct ds1216_priv *priv = platform_get_drvdata(pdev);
 111         struct ds1216_regs regs;
 112
 113         ds1216_switch_ds_to_clock(priv->ioaddr);
 114         ds1216_read(priv->ioaddr, (u8 *)&regs);
 115
 116         regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
 117         regs.sec = bin2bcd(tm->tm_sec);
 118         regs.min = bin2bcd(tm->tm_min);
 119         regs.hour &= DS1216_HOUR_1224;
 120         if (regs.hour && tm->tm_hour > 12) {
 121                 regs.hour |= DS1216_HOUR_AMPM;
 122                 tm->tm_hour -= 12;
 123         }
 124         regs.hour |= bin2bcd(tm->tm_hour);
 125         regs.wday &= ~7;
 126         regs.wday |= tm->tm_wday;
 127         regs.mday = bin2bcd(tm->tm_mday);
 128         regs.month = bin2bcd(tm->tm_mon);
 129         regs.year = bin2bcd(tm->tm_year % 100);
 130
 131         ds1216_switch_ds_to_clock(priv->ioaddr);
 132         ds1216_write(priv->ioaddr, (u8 *)&regs);
 133         return 0;
 134 }
 135
 136 static const struct rtc_class_ops ds1216_rtc_ops = {
 137         .read_time      = ds1216_rtc_read_time,
 138         .set_time       = ds1216_rtc_set_time,
 139 };
 140
 141 static int __init ds1216_rtc_probe(struct platform_device *pdev)
 142 {
 143         struct resource *res;
 144         struct ds1216_priv *priv;
 145         u8 dummy[8];
 146
 147         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 148         if (!priv)
 149                 return -ENOMEM;
 150
 151         platform_set_drvdata(pdev, priv);
 152
 153         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 154         priv->ioaddr = devm_ioremap_resource(&pdev->dev, res);
 155         if (IS_ERR(priv->ioaddr))
 156                 return PTR_ERR(priv->ioaddr);
 157
 158         priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216",
 159                                         &ds1216_rtc_ops, THIS_MODULE);
 160         if (IS_ERR(priv->rtc))
 161                 return PTR_ERR(priv->rtc);
 162
 163         /* dummy read to get clock into a known state */
 164         ds1216_read(priv->ioaddr, dummy);
 165         return 0;
 166 }
 167
 168 static struct platform_driver ds1216_rtc_platform_driver = {
 169         .driver         = {
 170                 .name   = "rtc-ds1216",
 171         },
 172 };
 173
 174 module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);
 175
 176 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
 177 MODULE_DESCRIPTION("DS1216 RTC driver");
 178 MODULE_LICENSE("GPL");
 179 MODULE_VERSION(DRV_VERSION);
 180 MODULE_ALIAS("platform:rtc-ds1216");