linux/drivers/rtc/rtc-ds1302.c
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   1/*
   2 * Dallas DS1302 RTC Support
   3 *
   4 *  Copyright (C) 2002  David McCullough
   5 *  Copyright (C) 2003 - 2007  Paul Mundt
   6 *
   7 * This file is subject to the terms and conditions of the GNU General Public
   8 * License version 2.  See the file "COPYING" in the main directory of
   9 * this archive for more details.
  10 */
  11#include <linux/init.h>
  12#include <linux/module.h>
  13#include <linux/kernel.h>
  14#include <linux/platform_device.h>
  15#include <linux/time.h>
  16#include <linux/rtc.h>
  17#include <linux/spinlock.h>
  18#include <linux/io.h>
  19#include <linux/bcd.h>
  20#include <asm/rtc.h>
  21
  22#define DRV_NAME        "rtc-ds1302"
  23#define DRV_VERSION     "0.1.0"
  24
  25#define RTC_CMD_READ    0x81            /* Read command */
  26#define RTC_CMD_WRITE   0x80            /* Write command */
  27
  28#define RTC_ADDR_RAM0   0x20            /* Address of RAM0 */
  29#define RTC_ADDR_TCR    0x08            /* Address of trickle charge register */
  30#define RTC_ADDR_YEAR   0x06            /* Address of year register */
  31#define RTC_ADDR_DAY    0x05            /* Address of day of week register */
  32#define RTC_ADDR_MON    0x04            /* Address of month register */
  33#define RTC_ADDR_DATE   0x03            /* Address of day of month register */
  34#define RTC_ADDR_HOUR   0x02            /* Address of hour register */
  35#define RTC_ADDR_MIN    0x01            /* Address of minute register */
  36#define RTC_ADDR_SEC    0x00            /* Address of second register */
  37
  38#define RTC_RESET       0x1000
  39#define RTC_IODATA      0x0800
  40#define RTC_SCLK        0x0400
  41
  42#ifdef CONFIG_SH_SECUREEDGE5410
  43#include <mach/snapgear.h>
  44#define set_dp(x)       SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
  45#define get_dp()        SECUREEDGE_READ_IOPORT()
  46#else
  47#error "Add support for your platform"
  48#endif
  49
  50struct ds1302_rtc {
  51        struct rtc_device *rtc_dev;
  52        spinlock_t lock;
  53};
  54
  55static void ds1302_sendbits(unsigned int val)
  56{
  57        int i;
  58
  59        for (i = 8; (i); i--, val >>= 1) {
  60                set_dp((get_dp() & ~RTC_IODATA) | ((val & 0x1) ?
  61                        RTC_IODATA : 0));
  62                set_dp(get_dp() | RTC_SCLK);    /* clock high */
  63                set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
  64        }
  65}
  66
  67static unsigned int ds1302_recvbits(void)
  68{
  69        unsigned int val;
  70        int i;
  71
  72        for (i = 0, val = 0; (i < 8); i++) {
  73                val |= (((get_dp() & RTC_IODATA) ? 1 : 0) << i);
  74                set_dp(get_dp() | RTC_SCLK);    /* clock high */
  75                set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
  76        }
  77
  78        return val;
  79}
  80
  81static unsigned int ds1302_readbyte(unsigned int addr)
  82{
  83        unsigned int val;
  84
  85        set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  86
  87        set_dp(get_dp() | RTC_RESET);
  88        ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
  89        val = ds1302_recvbits();
  90        set_dp(get_dp() & ~RTC_RESET);
  91
  92        return val;
  93}
  94
  95static void ds1302_writebyte(unsigned int addr, unsigned int val)
  96{
  97        set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  98        set_dp(get_dp() | RTC_RESET);
  99        ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
 100        ds1302_sendbits(val);
 101        set_dp(get_dp() & ~RTC_RESET);
 102}
 103
 104static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
 105{
 106        struct ds1302_rtc *rtc = dev_get_drvdata(dev);
 107
 108        spin_lock_irq(&rtc->lock);
 109
 110        tm->tm_sec      = bcd2bin(ds1302_readbyte(RTC_ADDR_SEC));
 111        tm->tm_min      = bcd2bin(ds1302_readbyte(RTC_ADDR_MIN));
 112        tm->tm_hour     = bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR));
 113        tm->tm_wday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DAY));
 114        tm->tm_mday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DATE));
 115        tm->tm_mon      = bcd2bin(ds1302_readbyte(RTC_ADDR_MON)) - 1;
 116        tm->tm_year     = bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR));
 117
 118        if (tm->tm_year < 70)
 119                tm->tm_year += 100;
 120
 121        spin_unlock_irq(&rtc->lock);
 122
 123        dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 124                "mday=%d, mon=%d, year=%d, wday=%d\n",
 125                __func__,
 126                tm->tm_sec, tm->tm_min, tm->tm_hour,
 127                tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);
 128
 129        if (rtc_valid_tm(tm) < 0)
 130                dev_err(dev, "invalid date\n");
 131
 132        return 0;
 133}
 134
 135static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
 136{
 137        struct ds1302_rtc *rtc = dev_get_drvdata(dev);
 138
 139        spin_lock_irq(&rtc->lock);
 140
 141        /* Stop RTC */
 142        ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);
 143
 144        ds1302_writebyte(RTC_ADDR_SEC, bin2bcd(tm->tm_sec));
 145        ds1302_writebyte(RTC_ADDR_MIN, bin2bcd(tm->tm_min));
 146        ds1302_writebyte(RTC_ADDR_HOUR, bin2bcd(tm->tm_hour));
 147        ds1302_writebyte(RTC_ADDR_DAY, bin2bcd(tm->tm_wday));
 148        ds1302_writebyte(RTC_ADDR_DATE, bin2bcd(tm->tm_mday));
 149        ds1302_writebyte(RTC_ADDR_MON, bin2bcd(tm->tm_mon + 1));
 150        ds1302_writebyte(RTC_ADDR_YEAR, bin2bcd(tm->tm_year % 100));
 151
 152        /* Start RTC */
 153        ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);
 154
 155        spin_unlock_irq(&rtc->lock);
 156
 157        return 0;
 158}
 159
 160static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
 161                            unsigned long arg)
 162{
 163        switch (cmd) {
 164#ifdef RTC_SET_CHARGE
 165        case RTC_SET_CHARGE:
 166        {
 167                struct ds1302_rtc *rtc = dev_get_drvdata(dev);
 168                int tcs_val;
 169
 170                if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
 171                        return -EFAULT;
 172
 173                spin_lock_irq(&rtc->lock);
 174                ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
 175                spin_unlock_irq(&rtc->lock);
 176                return 0;
 177        }
 178#endif
 179        }
 180
 181        return -ENOIOCTLCMD;
 182}
 183
 184static struct rtc_class_ops ds1302_rtc_ops = {
 185        .read_time      = ds1302_rtc_read_time,
 186        .set_time       = ds1302_rtc_set_time,
 187        .ioctl          = ds1302_rtc_ioctl,
 188};
 189
 190static int __devinit ds1302_rtc_probe(struct platform_device *pdev)
 191{
 192        struct ds1302_rtc *rtc;
 193        int ret;
 194
 195        /* Reset */
 196        set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
 197
 198        /* Write a magic value to the DS1302 RAM, and see if it sticks. */
 199        ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
 200        if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42)
 201                return -ENODEV;
 202
 203        rtc = kzalloc(sizeof(struct ds1302_rtc), GFP_KERNEL);
 204        if (unlikely(!rtc))
 205                return -ENOMEM;
 206
 207        spin_lock_init(&rtc->lock);
 208        rtc->rtc_dev = rtc_device_register("ds1302", &pdev->dev,
 209                                           &ds1302_rtc_ops, THIS_MODULE);
 210        if (IS_ERR(rtc->rtc_dev)) {
 211                ret = PTR_ERR(rtc->rtc_dev);
 212                goto out;
 213        }
 214
 215        platform_set_drvdata(pdev, rtc);
 216
 217        return 0;
 218out:
 219        kfree(rtc);
 220        return ret;
 221}
 222
 223static int __devexit ds1302_rtc_remove(struct platform_device *pdev)
 224{
 225        struct ds1302_rtc *rtc = platform_get_drvdata(pdev);
 226
 227        if (likely(rtc->rtc_dev))
 228                rtc_device_unregister(rtc->rtc_dev);
 229
 230        platform_set_drvdata(pdev, NULL);
 231
 232        kfree(rtc);
 233
 234        return 0;
 235}
 236
 237static struct platform_driver ds1302_platform_driver = {
 238        .driver         = {
 239                .name   = DRV_NAME,
 240                .owner  = THIS_MODULE,
 241        },
 242        .probe          = ds1302_rtc_probe,
 243        .remove         = __devexit_p(ds1302_rtc_remove),
 244};
 245
 246static int __init ds1302_rtc_init(void)
 247{
 248        return platform_driver_register(&ds1302_platform_driver);
 249}
 250
 251static void __exit ds1302_rtc_exit(void)
 252{
 253        platform_driver_unregister(&ds1302_platform_driver);
 254}
 255
 256module_init(ds1302_rtc_init);
 257module_exit(ds1302_rtc_exit);
 258
 259MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
 260MODULE_VERSION(DRV_VERSION);
 261MODULE_AUTHOR("Paul Mundt, David McCullough");
 262MODULE_LICENSE("GPL v2");
 263
The original LXR software by the LXR community, this experimental version by lxr@linux.no.