drivers/rtc/rtc-ds1302.c

   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 <asm/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
  50 struct ds1302_rtc {
  51         struct rtc_device *rtc_dev;
  52         spinlock_t lock;
  53 };
  54
  55 static 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
  67 static 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
  81 static 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
  95 static 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
 104 static 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
 135 static 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
 160 static 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
 184 static 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
 190 static 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;
 218 out:
 219         kfree(rtc);
 220         return ret;
 221 }
 222
 223 static 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
 237 static 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
 246 static int __init ds1302_rtc_init(void)
 247 {
 248         return platform_driver_register(&ds1302_platform_driver);
 249 }
 250
 251 static void __exit ds1302_rtc_exit(void)
 252 {
 253         platform_driver_unregister(&ds1302_platform_driver);
 254 }
 255
 256 module_init(ds1302_rtc_init);
 257 module_exit(ds1302_rtc_exit);
 258
 259 MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
 260 MODULE_VERSION(DRV_VERSION);
 261 MODULE_AUTHOR("Paul Mundt, David McCullough");
 262 MODULE_LICENSE("GPL v2");