LXR linux/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
  14struct 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
  28struct ds1216_priv {
  29        struct rtc_device *rtc;
  30        void __iomem *ioaddr;
  31};
  32
  33static 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 */
  42static 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
  55static 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
  69static 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
  77static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
  78{
  79        struct platform_device *pdev = to_platform_device(dev);
  80        struct ds1216_priv *priv = platform_get_drvdata(pdev);
  81        struct ds1216_regs regs;
  82
  83        ds1216_switch_ds_to_clock(priv->ioaddr);
  84        ds1216_read(priv->ioaddr, (u8 *)&regs);
  85
  86        tm->tm_sec = bcd2bin(regs.sec);
  87        tm->tm_min = bcd2bin(regs.min);
  88        if (regs.hour & DS1216_HOUR_1224) {
  89                /* AM/PM mode */
  90                tm->tm_hour = bcd2bin(regs.hour & 0x1f);
  91                if (regs.hour & DS1216_HOUR_AMPM)
  92                        tm->tm_hour += 12;
  93        } else
  94                tm->tm_hour = bcd2bin(regs.hour & 0x3f);
  95        tm->tm_wday = (regs.wday & 7) - 1;
  96        tm->tm_mday = bcd2bin(regs.mday & 0x3f);
  97        tm->tm_mon = bcd2bin(regs.month & 0x1f);
  98        tm->tm_year = bcd2bin(regs.year);
  99        if (tm->tm_year < 70)
 100                tm->tm_year += 100;
 101
 102        return rtc_valid_tm(tm);
 103}
 104
 105static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
 106{
 107        struct platform_device *pdev = to_platform_device(dev);
 108        struct ds1216_priv *priv = platform_get_drvdata(pdev);
 109        struct ds1216_regs regs;
 110
 111        ds1216_switch_ds_to_clock(priv->ioaddr);
 112        ds1216_read(priv->ioaddr, (u8 *)&regs);
 113
 114        regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
 115        regs.sec = bin2bcd(tm->tm_sec);
 116        regs.min = bin2bcd(tm->tm_min);
 117        regs.hour &= DS1216_HOUR_1224;
 118        if (regs.hour && tm->tm_hour > 12) {
 119                regs.hour |= DS1216_HOUR_AMPM;
 120                tm->tm_hour -= 12;
 121        }
 122        regs.hour |= bin2bcd(tm->tm_hour);
 123        regs.wday &= ~7;
 124        regs.wday |= tm->tm_wday;
 125        regs.mday = bin2bcd(tm->tm_mday);
 126        regs.month = bin2bcd(tm->tm_mon);
 127        regs.year = bin2bcd(tm->tm_year % 100);
 128
 129        ds1216_switch_ds_to_clock(priv->ioaddr);
 130        ds1216_write(priv->ioaddr, (u8 *)&regs);
 131        return 0;
 132}
 133
 134static const struct rtc_class_ops ds1216_rtc_ops = {
 135        .read_time      = ds1216_rtc_read_time,
 136        .set_time       = ds1216_rtc_set_time,
 137};
 138
 139static int __init ds1216_rtc_probe(struct platform_device *pdev)
 140{
 141        struct resource *res;
 142        struct ds1216_priv *priv;
 143        u8 dummy[8];
 144
 145        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 146        if (!priv)
 147                return -ENOMEM;
 148
 149        platform_set_drvdata(pdev, priv);
 150
 151        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 152        priv->ioaddr = devm_ioremap_resource(&pdev->dev, res);
 153        if (IS_ERR(priv->ioaddr))
 154                return PTR_ERR(priv->ioaddr);
 155
 156        priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216",
 157                                        &ds1216_rtc_ops, THIS_MODULE);
 158        if (IS_ERR(priv->rtc))
 159                return PTR_ERR(priv->rtc);
 160
 161        /* dummy read to get clock into a known state */
 162        ds1216_read(priv->ioaddr, dummy);
 163        return 0;
 164}
 165
 166static struct platform_driver ds1216_rtc_platform_driver = {
 167        .driver         = {
 168                .name   = "rtc-ds1216",
 169        },
 170};
 171
 172module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);
 173
 174MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
 175MODULE_DESCRIPTION("DS1216 RTC driver");
 176MODULE_LICENSE("GPL");
 177MODULE_ALIAS("platform:rtc-ds1216");
 178