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