linux/drivers/rtc/rtc-ds1216.c
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   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
  15struct 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
  29struct ds1216_priv {
  30        struct rtc_device *rtc;
  31        void __iomem *ioaddr;
  32        size_t size;
  33        unsigned long baseaddr;
  34};
  35
  36static 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 */
  45static 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
  58static 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
  72static 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
  80static 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
 108static 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
 137static const struct rtc_class_ops ds1216_rtc_ops = {
 138        .read_time      = ds1216_rtc_read_time,
 139        .set_time       = ds1216_rtc_set_time,
 140};
 141
 142static 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
 180out:
 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
 189static 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
 200static 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
 208static int __init ds1216_rtc_init(void)
 209{
 210        return platform_driver_probe(&ds1216_rtc_platform_driver, ds1216_rtc_probe);
 211}
 212
 213static void __exit ds1216_rtc_exit(void)
 214{
 215        platform_driver_unregister(&ds1216_rtc_platform_driver);
 216}
 217
 218MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
 219MODULE_DESCRIPTION("DS1216 RTC driver");
 220MODULE_LICENSE("GPL");
 221MODULE_VERSION(DRV_VERSION);
 222MODULE_ALIAS("platform:rtc-ds1216");
 223
 224module_init(ds1216_rtc_init);
 225module_exit(ds1216_rtc_exit);
 226