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 struct 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
  28 struct ds1216_priv {
  29         struct rtc_device *rtc;
  30         void __iomem *ioaddr;
  31 };
  32
  33 static 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  */
  42 static 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
  55 static 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
  69 static 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
  77 static 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
 105 static 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
 134 static const struct rtc_class_ops ds1216_rtc_ops = {
 135         .read_time      = ds1216_rtc_read_time,
 136         .set_time       = ds1216_rtc_set_time,
 137 };
 138
 139 static 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
 166 static struct platform_driver ds1216_rtc_platform_driver = {
 167         .driver         = {
 168                 .name   = "rtc-ds1216",
 169         },
 170 };
 171
 172 module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);
 173
 174 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
 175 MODULE_DESCRIPTION("DS1216 RTC driver");
 176 MODULE_LICENSE("GPL");
 177 MODULE_ALIAS("platform:rtc-ds1216");