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