drivers/rtc/rtc-m48t35.c

   1 /*
   2  * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
   3  *
   4  * Copyright (C) 2000 Silicon Graphics, Inc.
   5  * Written by Ulf Carlsson (ulfc@engr.sgi.com)
   6  *
   7  * Copyright (C) 2008 Thomas Bogendoerfer
   8  *
   9  * Based on code written by Paul Gortmaker.
  10  *
  11  * This program is free software; you can redistribute it and/or modify it
  12  * under the terms of the GNU General Public License as published by the
  13  * Free Software Foundation; either version 2 of the License, or (at your
  14  * option) any later version.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/rtc.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/bcd.h>
  21
  22 #define DRV_VERSION             "1.0"
  23
  24 struct m48t35_rtc {
  25         u8      pad[0x7ff8];    /* starts at 0x7ff8 */
  26         u8      control;
  27         u8      sec;
  28         u8      min;
  29         u8      hour;
  30         u8      day;
  31         u8      date;
  32         u8      month;
  33         u8      year;
  34 };
  35
  36 #define M48T35_RTC_SET          0x80
  37 #define M48T35_RTC_READ         0x40
  38
  39 struct m48t35_priv {
  40         struct rtc_device *rtc;
  41         struct m48t35_rtc __iomem *reg;
  42         size_t size;
  43         unsigned long baseaddr;
  44         spinlock_t lock;
  45 };
  46
  47 static int m48t35_read_time(struct device *dev, struct rtc_time *tm)
  48 {
  49         struct m48t35_priv *priv = dev_get_drvdata(dev);
  50         u8 control;
  51
  52         /*
  53          * Only the values that we read from the RTC are set. We leave
  54          * tm_wday, tm_yday and tm_isdst untouched. Even though the
  55          * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
  56          * by the RTC when initially set to a non-zero value.
  57          */
  58         spin_lock_irq(&priv->lock);
  59         control = readb(&priv->reg->control);
  60         writeb(control | M48T35_RTC_READ, &priv->reg->control);
  61         tm->tm_sec = readb(&priv->reg->sec);
  62         tm->tm_min = readb(&priv->reg->min);
  63         tm->tm_hour = readb(&priv->reg->hour);
  64         tm->tm_mday = readb(&priv->reg->date);
  65         tm->tm_mon = readb(&priv->reg->month);
  66         tm->tm_year = readb(&priv->reg->year);
  67         writeb(control, &priv->reg->control);
  68         spin_unlock_irq(&priv->lock);
  69
  70         tm->tm_sec = bcd2bin(tm->tm_sec);
  71         tm->tm_min = bcd2bin(tm->tm_min);
  72         tm->tm_hour = bcd2bin(tm->tm_hour);
  73         tm->tm_mday = bcd2bin(tm->tm_mday);
  74         tm->tm_mon = bcd2bin(tm->tm_mon);
  75         tm->tm_year = bcd2bin(tm->tm_year);
  76
  77         /*
  78          * Account for differences between how the RTC uses the values
  79          * and how they are defined in a struct rtc_time;
  80          */
  81         tm->tm_year += 70;
  82         if (tm->tm_year <= 69)
  83                 tm->tm_year += 100;
  84
  85         tm->tm_mon--;
  86         return rtc_valid_tm(tm);
  87 }
  88
  89 static int m48t35_set_time(struct device *dev, struct rtc_time *tm)
  90 {
  91         struct m48t35_priv *priv = dev_get_drvdata(dev);
  92         unsigned char mon, day, hrs, min, sec;
  93         unsigned int yrs;
  94         u8 control;
  95
  96         yrs = tm->tm_year + 1900;
  97         mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
  98         day = tm->tm_mday;
  99         hrs = tm->tm_hour;
 100         min = tm->tm_min;
 101         sec = tm->tm_sec;
 102
 103         if (yrs < 1970)
 104                 return -EINVAL;
 105
 106         yrs -= 1970;
 107         if (yrs > 255)    /* They are unsigned */
 108                 return -EINVAL;
 109
 110         if (yrs > 169)
 111                 return -EINVAL;
 112
 113         if (yrs >= 100)
 114                 yrs -= 100;
 115
 116         sec = bin2bcd(sec);
 117         min = bin2bcd(min);
 118         hrs = bin2bcd(hrs);
 119         day = bin2bcd(day);
 120         mon = bin2bcd(mon);
 121         yrs = bin2bcd(yrs);
 122
 123         spin_lock_irq(&priv->lock);
 124         control = readb(&priv->reg->control);
 125         writeb(control | M48T35_RTC_SET, &priv->reg->control);
 126         writeb(yrs, &priv->reg->year);
 127         writeb(mon, &priv->reg->month);
 128         writeb(day, &priv->reg->date);
 129         writeb(hrs, &priv->reg->hour);
 130         writeb(min, &priv->reg->min);
 131         writeb(sec, &priv->reg->sec);
 132         writeb(control, &priv->reg->control);
 133         spin_unlock_irq(&priv->lock);
 134         return 0;
 135 }
 136
 137 static const struct rtc_class_ops m48t35_ops = {
 138         .read_time      = m48t35_read_time,
 139         .set_time       = m48t35_set_time,
 140 };
 141
 142 static int __devinit m48t35_probe(struct platform_device *pdev)
 143 {
 144         struct rtc_device *rtc;
 145         struct resource *res;
 146         struct m48t35_priv *priv;
 147         int ret = 0;
 148
 149         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 150         if (!res)
 151                 return -ENODEV;
 152         priv = kzalloc(sizeof(struct m48t35_priv), GFP_KERNEL);
 153         if (!priv)
 154                 return -ENOMEM;
 155
 156         priv->size = res->end - res->start + 1;
 157         /*
 158          * kludge: remove the #ifndef after ioc3 resource
 159          * conflicts are resolved
 160          */
 161 #ifndef CONFIG_SGI_IP27
 162         if (!request_mem_region(res->start, priv->size, pdev->name)) {
 163                 ret = -EBUSY;
 164                 goto out;
 165         }
 166 #endif
 167         priv->baseaddr = res->start;
 168         priv->reg = ioremap(priv->baseaddr, priv->size);
 169         if (!priv->reg) {
 170                 ret = -ENOMEM;
 171                 goto out;
 172         }
 173         spin_lock_init(&priv->lock);
 174         rtc = rtc_device_register("m48t35", &pdev->dev,
 175                                   &m48t35_ops, THIS_MODULE);
 176         if (IS_ERR(rtc)) {
 177                 ret = PTR_ERR(rtc);
 178                 goto out;
 179         }
 180         priv->rtc = rtc;
 181         platform_set_drvdata(pdev, priv);
 182         return 0;
 183
 184 out:
 185         if (priv->rtc)
 186                 rtc_device_unregister(priv->rtc);
 187         if (priv->reg)
 188                 iounmap(priv->reg);
 189         if (priv->baseaddr)
 190                 release_mem_region(priv->baseaddr, priv->size);
 191         kfree(priv);
 192         return ret;
 193 }
 194
 195 static int __devexit m48t35_remove(struct platform_device *pdev)
 196 {
 197         struct m48t35_priv *priv = platform_get_drvdata(pdev);
 198
 199         rtc_device_unregister(priv->rtc);
 200         iounmap(priv->reg);
 201 #ifndef CONFIG_SGI_IP27
 202         release_mem_region(priv->baseaddr, priv->size);
 203 #endif
 204         kfree(priv);
 205         return 0;
 206 }
 207
 208 static struct platform_driver m48t35_platform_driver = {
 209         .driver         = {
 210                 .name   = "rtc-m48t35",
 211                 .owner  = THIS_MODULE,
 212         },
 213         .probe          = m48t35_probe,
 214         .remove         = __devexit_p(m48t35_remove),
 215 };
 216
 217 static int __init m48t35_init(void)
 218 {
 219         return platform_driver_register(&m48t35_platform_driver);
 220 }
 221
 222 static void __exit m48t35_exit(void)
 223 {
 224         platform_driver_unregister(&m48t35_platform_driver);
 225 }
 226
 227 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
 228 MODULE_DESCRIPTION("M48T35 RTC driver");
 229 MODULE_LICENSE("GPL");
 230 MODULE_VERSION(DRV_VERSION);
 231 MODULE_ALIAS("platform:rtc-m48t35");
 232
 233 module_init(m48t35_init);
 234 module_exit(m48t35_exit);