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 "0.2"
  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
 105         return rtc_valid_tm(tm);
 106 }
 107
 108 static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
 109 {
 110         struct platform_device *pdev = to_platform_device(dev);
 111         struct ds1216_priv *priv = platform_get_drvdata(pdev);
 112         struct ds1216_regs regs;
 113
 114         ds1216_switch_ds_to_clock(priv->ioaddr);
 115         ds1216_read(priv->ioaddr, (u8 *)&regs);
 116
 117         regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
 118         regs.sec = bin2bcd(tm->tm_sec);
 119         regs.min = bin2bcd(tm->tm_min);
 120         regs.hour &= DS1216_HOUR_1224;
 121         if (regs.hour && tm->tm_hour > 12) {
 122                 regs.hour |= DS1216_HOUR_AMPM;
 123                 tm->tm_hour -= 12;
 124         }
 125         regs.hour |= bin2bcd(tm->tm_hour);
 126         regs.wday &= ~7;
 127         regs.wday |= tm->tm_wday;
 128         regs.mday = bin2bcd(tm->tm_mday);
 129         regs.month = bin2bcd(tm->tm_mon);
 130         regs.year = bin2bcd(tm->tm_year % 100);
 131
 132         ds1216_switch_ds_to_clock(priv->ioaddr);
 133         ds1216_write(priv->ioaddr, (u8 *)&regs);
 134         return 0;
 135 }
 136
 137 static const struct rtc_class_ops ds1216_rtc_ops = {
 138         .read_time      = ds1216_rtc_read_time,
 139         .set_time       = ds1216_rtc_set_time,
 140 };
 141
 142 static int __init ds1216_rtc_probe(struct platform_device *pdev)
 143 {
 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
 156         platform_set_drvdata(pdev, priv);
 157
 158         priv->size = resource_size(res);
 159         if (!request_mem_region(res->start, priv->size, pdev->name)) {
 160                 ret = -EBUSY;
 161                 goto out;
 162         }
 163         priv->baseaddr = res->start;
 164         priv->ioaddr = ioremap(priv->baseaddr, priv->size);
 165         if (!priv->ioaddr) {
 166                 ret = -ENOMEM;
 167                 goto out;
 168         }
 169         priv->rtc = rtc_device_register("ds1216", &pdev->dev,
 170                                   &ds1216_rtc_ops, THIS_MODULE);
 171         if (IS_ERR(priv->rtc)) {
 172                 ret = PTR_ERR(priv->rtc);
 173                 goto out;
 174         }
 175
 176         /* dummy read to get clock into a known state */
 177         ds1216_read(priv->ioaddr, dummy);
 178         return 0;
 179
 180 out:
 181         if (priv->ioaddr)
 182                 iounmap(priv->ioaddr);
 183         if (priv->baseaddr)
 184                 release_mem_region(priv->baseaddr, priv->size);
 185         kfree(priv);
 186         return ret;
 187 }
 188
 189 static int __exit ds1216_rtc_remove(struct platform_device *pdev)
 190 {
 191         struct ds1216_priv *priv = platform_get_drvdata(pdev);
 192
 193         rtc_device_unregister(priv->rtc);
 194         iounmap(priv->ioaddr);
 195         release_mem_region(priv->baseaddr, priv->size);
 196         kfree(priv);
 197         return 0;
 198 }
 199
 200 static struct platform_driver ds1216_rtc_platform_driver = {
 201         .driver         = {
 202                 .name   = "rtc-ds1216",
 203                 .owner  = THIS_MODULE,
 204         },
 205         .remove         = __exit_p(ds1216_rtc_remove),
 206 };
 207
 208 static int __init ds1216_rtc_init(void)
 209 {
 210         return platform_driver_probe(&ds1216_rtc_platform_driver, ds1216_rtc_probe);
 211 }
 212
 213 static void __exit ds1216_rtc_exit(void)
 214 {
 215         platform_driver_unregister(&ds1216_rtc_platform_driver);
 216 }
 217
 218 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
 219 MODULE_DESCRIPTION("DS1216 RTC driver");
 220 MODULE_LICENSE("GPL");
 221 MODULE_VERSION(DRV_VERSION);
 222 MODULE_ALIAS("platform:rtc-ds1216");
 223
 224 module_init(ds1216_rtc_init);
 225 module_exit(ds1216_rtc_exit);