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
  13 #define DRV_VERSION "0.1"
  14
  15 struct ds1216_regs {
  16         u8 tsec;
  17         u8 sec;
  18         u8 min;
  19         u8 hour;
  20         u8 wday;
  21         u8 mday;
  22         u8 month;
  23         u8 year;
  24 };
  25
  26 #define DS1216_HOUR_1224        (1 << 7)
  27 #define DS1216_HOUR_AMPM        (1 << 5)
  28
  29 struct ds1216_priv {
  30         struct rtc_device *rtc;
  31         void __iomem *ioaddr;
  32         size_t size;
  33         unsigned long baseaddr;
  34 };
  35
  36 static const u8 magic[] = {
  37         0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c
  38 };
  39
  40 /*
  41  * Read the 64 bit we'd like to have - It a series
  42  * of 64 bits showing up in the LSB of the base register.
  43  *
  44  */
  45 static void ds1216_read(u8 __iomem *ioaddr, u8 *buf)
  46 {
  47         unsigned char c;
  48         int i, j;
  49
  50         for (i = 0; i < 8; i++) {
  51                 c = 0;
  52                 for (j = 0; j < 8; j++)
  53                         c |= (readb(ioaddr) & 0x1) << j;
  54                 buf[i] = c;
  55         }
  56 }
  57
  58 static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf)
  59 {
  60         unsigned char c;
  61         int i, j;
  62
  63         for (i = 0; i < 8; i++) {
  64                 c = buf[i];
  65                 for (j = 0; j < 8; j++) {
  66                         writeb(c, ioaddr);
  67                         c = c >> 1;
  68                 }
  69         }
  70 }
  71
  72 static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr)
  73 {
  74         /* Reset magic pointer */
  75         readb(ioaddr);
  76         /* Write 64 bit magic to DS1216 */
  77         ds1216_write(ioaddr, magic);
  78 }
  79
  80 static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
  81 {
  82         struct platform_device *pdev = to_platform_device(dev);
  83         struct ds1216_priv *priv = platform_get_drvdata(pdev);
  84         struct ds1216_regs regs;
  85
  86         ds1216_switch_ds_to_clock(priv->ioaddr);
  87         ds1216_read(priv->ioaddr, (u8 *)&regs);
  88
  89         tm->tm_sec = bcd2bin(regs.sec);
  90         tm->tm_min = bcd2bin(regs.min);
  91         if (regs.hour & DS1216_HOUR_1224) {
  92                 /* AM/PM mode */
  93                 tm->tm_hour = bcd2bin(regs.hour & 0x1f);
  94                 if (regs.hour & DS1216_HOUR_AMPM)
  95                         tm->tm_hour += 12;
  96         } else
  97                 tm->tm_hour = bcd2bin(regs.hour & 0x3f);
  98         tm->tm_wday = (regs.wday & 7) - 1;
  99         tm->tm_mday = bcd2bin(regs.mday & 0x3f);
 100         tm->tm_mon = bcd2bin(regs.month & 0x1f);
 101         tm->tm_year = bcd2bin(regs.year);
 102         if (tm->tm_year < 70)
 103                 tm->tm_year += 100;
 104         return 0;
 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 __devinit ds1216_rtc_probe(struct platform_device *pdev)
 142 {
 143         struct rtc_device *rtc;
 144         struct resource *res;
 145         struct ds1216_priv *priv;
 146         int ret = 0;
 147         u8 dummy[8];
 148
 149         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 150         if (!res)
 151                 return -ENODEV;
 152         priv = kzalloc(sizeof *priv, GFP_KERNEL);
 153         if (!priv)
 154                 return -ENOMEM;
 155         priv->size = res->end - res->start + 1;
 156         if (!request_mem_region(res->start, priv->size, pdev->name)) {
 157                 ret = -EBUSY;
 158                 goto out;
 159         }
 160         priv->baseaddr = res->start;
 161         priv->ioaddr = ioremap(priv->baseaddr, priv->size);
 162         if (!priv->ioaddr) {
 163                 ret = -ENOMEM;
 164                 goto out;
 165         }
 166         rtc = rtc_device_register("ds1216", &pdev->dev,
 167                                   &ds1216_rtc_ops, THIS_MODULE);
 168         if (IS_ERR(rtc)) {
 169                 ret = PTR_ERR(rtc);
 170                 goto out;
 171         }
 172         priv->rtc = rtc;
 173         platform_set_drvdata(pdev, priv);
 174
 175         /* dummy read to get clock into a known state */
 176         ds1216_read(priv->ioaddr, dummy);
 177         return 0;
 178
 179 out:
 180         if (priv->rtc)
 181                 rtc_device_unregister(priv->rtc);
 182         if (priv->ioaddr)
 183                 iounmap(priv->ioaddr);
 184         if (priv->baseaddr)
 185                 release_mem_region(priv->baseaddr, priv->size);
 186         kfree(priv);
 187         return ret;
 188 }
 189
 190 static int __devexit ds1216_rtc_remove(struct platform_device *pdev)
 191 {
 192         struct ds1216_priv *priv = platform_get_drvdata(pdev);
 193
 194         rtc_device_unregister(priv->rtc);
 195         iounmap(priv->ioaddr);
 196         release_mem_region(priv->baseaddr, priv->size);
 197         kfree(priv);
 198         return 0;
 199 }
 200
 201 static struct platform_driver ds1216_rtc_platform_driver = {
 202         .driver         = {
 203                 .name   = "rtc-ds1216",
 204                 .owner  = THIS_MODULE,
 205         },
 206         .probe          = ds1216_rtc_probe,
 207         .remove         = __devexit_p(ds1216_rtc_remove),
 208 };
 209
 210 static int __init ds1216_rtc_init(void)
 211 {
 212         return platform_driver_register(&ds1216_rtc_platform_driver);
 213 }
 214
 215 static void __exit ds1216_rtc_exit(void)
 216 {
 217         platform_driver_unregister(&ds1216_rtc_platform_driver);
 218 }
 219
 220 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
 221 MODULE_DESCRIPTION("DS1216 RTC driver");
 222 MODULE_LICENSE("GPL");
 223 MODULE_VERSION(DRV_VERSION);
 224 MODULE_ALIAS("platform:rtc-ds1216");
 225
 226 module_init(ds1216_rtc_init);
 227 module_exit(ds1216_rtc_exit);