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         size_t size;
  34         unsigned long baseaddr;
  35 };
  36
  37 static const u8 magic[] = {
  38         0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c
  39 };
  40
  41 /*
  42  * Read the 64 bit we'd like to have - It a series
  43  * of 64 bits showing up in the LSB of the base register.
  44  *
  45  */
  46 static void ds1216_read(u8 __iomem *ioaddr, u8 *buf)
  47 {
  48         unsigned char c;
  49         int i, j;
  50
  51         for (i = 0; i < 8; i++) {
  52                 c = 0;
  53                 for (j = 0; j < 8; j++)
  54                         c |= (readb(ioaddr) & 0x1) << j;
  55                 buf[i] = c;
  56         }
  57 }
  58
  59 static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf)
  60 {
  61         unsigned char c;
  62         int i, j;
  63
  64         for (i = 0; i < 8; i++) {
  65                 c = buf[i];
  66                 for (j = 0; j < 8; j++) {
  67                         writeb(c, ioaddr);
  68                         c = c >> 1;
  69                 }
  70         }
  71 }
  72
  73 static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr)
  74 {
  75         /* Reset magic pointer */
  76         readb(ioaddr);
  77         /* Write 64 bit magic to DS1216 */
  78         ds1216_write(ioaddr, magic);
  79 }
  80
  81 static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
  82 {
  83         struct platform_device *pdev = to_platform_device(dev);
  84         struct ds1216_priv *priv = platform_get_drvdata(pdev);
  85         struct ds1216_regs regs;
  86
  87         ds1216_switch_ds_to_clock(priv->ioaddr);
  88         ds1216_read(priv->ioaddr, (u8 *)&regs);
  89
  90         tm->tm_sec = bcd2bin(regs.sec);
  91         tm->tm_min = bcd2bin(regs.min);
  92         if (regs.hour & DS1216_HOUR_1224) {
  93                 /* AM/PM mode */
  94                 tm->tm_hour = bcd2bin(regs.hour & 0x1f);
  95                 if (regs.hour & DS1216_HOUR_AMPM)
  96                         tm->tm_hour += 12;
  97         } else
  98                 tm->tm_hour = bcd2bin(regs.hour & 0x3f);
  99         tm->tm_wday = (regs.wday & 7) - 1;
 100         tm->tm_mday = bcd2bin(regs.mday & 0x3f);
 101         tm->tm_mon = bcd2bin(regs.month & 0x1f);
 102         tm->tm_year = bcd2bin(regs.year);
 103         if (tm->tm_year < 70)
 104                 tm->tm_year += 100;
 105
 106         return rtc_valid_tm(tm);
 107 }
 108
 109 static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
 110 {
 111         struct platform_device *pdev = to_platform_device(dev);
 112         struct ds1216_priv *priv = platform_get_drvdata(pdev);
 113         struct ds1216_regs regs;
 114
 115         ds1216_switch_ds_to_clock(priv->ioaddr);
 116         ds1216_read(priv->ioaddr, (u8 *)&regs);
 117
 118         regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
 119         regs.sec = bin2bcd(tm->tm_sec);
 120         regs.min = bin2bcd(tm->tm_min);
 121         regs.hour &= DS1216_HOUR_1224;
 122         if (regs.hour && tm->tm_hour > 12) {
 123                 regs.hour |= DS1216_HOUR_AMPM;
 124                 tm->tm_hour -= 12;
 125         }
 126         regs.hour |= bin2bcd(tm->tm_hour);
 127         regs.wday &= ~7;
 128         regs.wday |= tm->tm_wday;
 129         regs.mday = bin2bcd(tm->tm_mday);
 130         regs.month = bin2bcd(tm->tm_mon);
 131         regs.year = bin2bcd(tm->tm_year % 100);
 132
 133         ds1216_switch_ds_to_clock(priv->ioaddr);
 134         ds1216_write(priv->ioaddr, (u8 *)&regs);
 135         return 0;
 136 }
 137
 138 static const struct rtc_class_ops ds1216_rtc_ops = {
 139         .read_time      = ds1216_rtc_read_time,
 140         .set_time       = ds1216_rtc_set_time,
 141 };
 142
 143 static int __init ds1216_rtc_probe(struct platform_device *pdev)
 144 {
 145         struct resource *res;
 146         struct ds1216_priv *priv;
 147         int ret = 0;
 148         u8 dummy[8];
 149
 150         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 151         if (!res)
 152                 return -ENODEV;
 153         priv = kzalloc(sizeof *priv, GFP_KERNEL);
 154         if (!priv)
 155                 return -ENOMEM;
 156
 157         platform_set_drvdata(pdev, priv);
 158
 159         priv->size = resource_size(res);
 160         if (!request_mem_region(res->start, priv->size, pdev->name)) {
 161                 ret = -EBUSY;
 162                 goto out;
 163         }
 164         priv->baseaddr = res->start;
 165         priv->ioaddr = ioremap(priv->baseaddr, priv->size);
 166         if (!priv->ioaddr) {
 167                 ret = -ENOMEM;
 168                 goto out;
 169         }
 170         priv->rtc = rtc_device_register("ds1216", &pdev->dev,
 171                                   &ds1216_rtc_ops, THIS_MODULE);
 172         if (IS_ERR(priv->rtc)) {
 173                 ret = PTR_ERR(priv->rtc);
 174                 goto out;
 175         }
 176
 177         /* dummy read to get clock into a known state */
 178         ds1216_read(priv->ioaddr, dummy);
 179         return 0;
 180
 181 out:
 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 __exit 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         .remove         = __exit_p(ds1216_rtc_remove),
 207 };
 208
 209 static int __init ds1216_rtc_init(void)
 210 {
 211         return platform_driver_probe(&ds1216_rtc_platform_driver, ds1216_rtc_probe);
 212 }
 213
 214 static void __exit ds1216_rtc_exit(void)
 215 {
 216         platform_driver_unregister(&ds1216_rtc_platform_driver);
 217 }
 218
 219 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
 220 MODULE_DESCRIPTION("DS1216 RTC driver");
 221 MODULE_LICENSE("GPL");
 222 MODULE_VERSION(DRV_VERSION);
 223 MODULE_ALIAS("platform:rtc-ds1216");
 224
 225 module_init(ds1216_rtc_init);
 226 module_exit(ds1216_rtc_exit);