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
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/kernel.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/rtc.h>
  17 #include <linux/io.h>
  18 #include <linux/bcd.h>
  19 #include <asm/rtc.h>
  20
  21 #define DRV_NAME        "rtc-ds1302"
  22 #define DRV_VERSION     "0.1.1"
  23
  24 #define RTC_CMD_READ    0x81            /* Read command */
  25 #define RTC_CMD_WRITE   0x80            /* Write command */
  26
  27 #define RTC_ADDR_RAM0   0x20            /* Address of RAM0 */
  28 #define RTC_ADDR_TCR    0x08            /* Address of trickle charge register */
  29 #define RTC_ADDR_YEAR   0x06            /* Address of year register */
  30 #define RTC_ADDR_DAY    0x05            /* Address of day of week register */
  31 #define RTC_ADDR_MON    0x04            /* Address of month register */
  32 #define RTC_ADDR_DATE   0x03            /* Address of day of month register */
  33 #define RTC_ADDR_HOUR   0x02            /* Address of hour register */
  34 #define RTC_ADDR_MIN    0x01            /* Address of minute register */
  35 #define RTC_ADDR_SEC    0x00            /* Address of second register */
  36
  37 #define RTC_RESET       0x1000
  38 #define RTC_IODATA      0x0800
  39 #define RTC_SCLK        0x0400
  40
  41 #ifdef CONFIG_SH_SECUREEDGE5410
  42 #include <mach/snapgear.h>
  43 #define set_dp(x)       SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
  44 #define get_dp()        SECUREEDGE_READ_IOPORT()
  45 #else
  46 #error "Add support for your platform"
  47 #endif
  48
  49 static void ds1302_sendbits(unsigned int val)
  50 {
  51         int i;
  52
  53         for (i = 8; (i); i--, val >>= 1) {
  54                 set_dp((get_dp() & ~RTC_IODATA) | ((val & 0x1) ?
  55                         RTC_IODATA : 0));
  56                 set_dp(get_dp() | RTC_SCLK);    /* clock high */
  57                 set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
  58         }
  59 }
  60
  61 static unsigned int ds1302_recvbits(void)
  62 {
  63         unsigned int val;
  64         int i;
  65
  66         for (i = 0, val = 0; (i < 8); i++) {
  67                 val |= (((get_dp() & RTC_IODATA) ? 1 : 0) << i);
  68                 set_dp(get_dp() | RTC_SCLK);    /* clock high */
  69                 set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
  70         }
  71
  72         return val;
  73 }
  74
  75 static unsigned int ds1302_readbyte(unsigned int addr)
  76 {
  77         unsigned int val;
  78
  79         set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  80
  81         set_dp(get_dp() | RTC_RESET);
  82         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
  83         val = ds1302_recvbits();
  84         set_dp(get_dp() & ~RTC_RESET);
  85
  86         return val;
  87 }
  88
  89 static void ds1302_writebyte(unsigned int addr, unsigned int val)
  90 {
  91         set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  92         set_dp(get_dp() | RTC_RESET);
  93         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
  94         ds1302_sendbits(val);
  95         set_dp(get_dp() & ~RTC_RESET);
  96 }
  97
  98 static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
  99 {
 100         tm->tm_sec      = bcd2bin(ds1302_readbyte(RTC_ADDR_SEC));
 101         tm->tm_min      = bcd2bin(ds1302_readbyte(RTC_ADDR_MIN));
 102         tm->tm_hour     = bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR));
 103         tm->tm_wday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DAY));
 104         tm->tm_mday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DATE));
 105         tm->tm_mon      = bcd2bin(ds1302_readbyte(RTC_ADDR_MON)) - 1;
 106         tm->tm_year     = bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR));
 107
 108         if (tm->tm_year < 70)
 109                 tm->tm_year += 100;
 110
 111         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 112                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 113                 __func__,
 114                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 115                 tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);
 116
 117         return rtc_valid_tm(tm);
 118 }
 119
 120 static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
 121 {
 122         /* Stop RTC */
 123         ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);
 124
 125         ds1302_writebyte(RTC_ADDR_SEC, bin2bcd(tm->tm_sec));
 126         ds1302_writebyte(RTC_ADDR_MIN, bin2bcd(tm->tm_min));
 127         ds1302_writebyte(RTC_ADDR_HOUR, bin2bcd(tm->tm_hour));
 128         ds1302_writebyte(RTC_ADDR_DAY, bin2bcd(tm->tm_wday));
 129         ds1302_writebyte(RTC_ADDR_DATE, bin2bcd(tm->tm_mday));
 130         ds1302_writebyte(RTC_ADDR_MON, bin2bcd(tm->tm_mon + 1));
 131         ds1302_writebyte(RTC_ADDR_YEAR, bin2bcd(tm->tm_year % 100));
 132
 133         /* Start RTC */
 134         ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);
 135
 136         return 0;
 137 }
 138
 139 static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
 140                             unsigned long arg)
 141 {
 142         switch (cmd) {
 143 #ifdef RTC_SET_CHARGE
 144         case RTC_SET_CHARGE:
 145         {
 146                 struct ds1302_rtc *rtc = dev_get_drvdata(dev);
 147                 int tcs_val;
 148
 149                 if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
 150                         return -EFAULT;
 151
 152                 ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
 153                 return 0;
 154         }
 155 #endif
 156         }
 157
 158         return -ENOIOCTLCMD;
 159 }
 160
 161 static struct rtc_class_ops ds1302_rtc_ops = {
 162         .read_time      = ds1302_rtc_read_time,
 163         .set_time       = ds1302_rtc_set_time,
 164         .ioctl          = ds1302_rtc_ioctl,
 165 };
 166
 167 static int __init ds1302_rtc_probe(struct platform_device *pdev)
 168 {
 169         struct rtc_device *rtc;
 170
 171         /* Reset */
 172         set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
 173
 174         /* Write a magic value to the DS1302 RAM, and see if it sticks. */
 175         ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
 176         if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42)
 177                 return -ENODEV;
 178
 179         rtc = rtc_device_register("ds1302", &pdev->dev,
 180                                            &ds1302_rtc_ops, THIS_MODULE);
 181         if (IS_ERR(rtc))
 182                 return PTR_ERR(rtc);
 183
 184         platform_set_drvdata(pdev, rtc);
 185
 186         return 0;
 187 }
 188
 189 static int __devexit ds1302_rtc_remove(struct platform_device *pdev)
 190 {
 191         struct rtc_device *rtc = platform_get_drvdata(pdev);
 192
 193         rtc_device_unregister(rtc);
 194         platform_set_drvdata(pdev, NULL);
 195
 196         return 0;
 197 }
 198
 199 static struct platform_driver ds1302_platform_driver = {
 200         .driver         = {
 201                 .name   = DRV_NAME,
 202                 .owner  = THIS_MODULE,
 203         },
 204         .remove         = __exit_p(ds1302_rtc_remove),
 205 };
 206
 207 static int __init ds1302_rtc_init(void)
 208 {
 209         return platform_driver_probe(&ds1302_platform_driver, ds1302_rtc_probe);
 210 }
 211
 212 static void __exit ds1302_rtc_exit(void)
 213 {
 214         platform_driver_unregister(&ds1302_platform_driver);
 215 }
 216
 217 module_init(ds1302_rtc_init);
 218 module_exit(ds1302_rtc_exit);
 219
 220 MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
 221 MODULE_VERSION(DRV_VERSION);
 222 MODULE_AUTHOR("Paul Mundt, David McCullough");
 223 MODULE_LICENSE("GPL v2");