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
  20 #define DRV_NAME        "rtc-ds1302"
  21 #define DRV_VERSION     "0.1.1"
  22
  23 #define RTC_CMD_READ    0x81            /* Read command */
  24 #define RTC_CMD_WRITE   0x80            /* Write command */
  25
  26 #define RTC_ADDR_RAM0   0x20            /* Address of RAM0 */
  27 #define RTC_ADDR_TCR    0x08            /* Address of trickle charge register */
  28 #define RTC_ADDR_YEAR   0x06            /* Address of year register */
  29 #define RTC_ADDR_DAY    0x05            /* Address of day of week register */
  30 #define RTC_ADDR_MON    0x04            /* Address of month register */
  31 #define RTC_ADDR_DATE   0x03            /* Address of day of month register */
  32 #define RTC_ADDR_HOUR   0x02            /* Address of hour register */
  33 #define RTC_ADDR_MIN    0x01            /* Address of minute register */
  34 #define RTC_ADDR_SEC    0x00            /* Address of second register */
  35
  36 #ifdef CONFIG_SH_SECUREEDGE5410
  37 #include <asm/rtc.h>
  38 #include <mach/secureedge5410.h>
  39
  40 #define RTC_RESET       0x1000
  41 #define RTC_IODATA      0x0800
  42 #define RTC_SCLK        0x0400
  43
  44 #define set_dp(x)       SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
  45 #define get_dp()        SECUREEDGE_READ_IOPORT()
  46 #define ds1302_set_tx()
  47 #define ds1302_set_rx()
  48
  49 static inline int ds1302_hw_init(void)
  50 {
  51         return 0;
  52 }
  53
  54 static inline void ds1302_reset(void)
  55 {
  56         set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  57 }
  58
  59 static inline void ds1302_clock(void)
  60 {
  61         set_dp(get_dp() | RTC_SCLK);    /* clock high */
  62         set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
  63 }
  64
  65 static inline void ds1302_start(void)
  66 {
  67         set_dp(get_dp() | RTC_RESET);
  68 }
  69
  70 static inline void ds1302_stop(void)
  71 {
  72         set_dp(get_dp() & ~RTC_RESET);
  73 }
  74
  75 static inline void ds1302_txbit(int bit)
  76 {
  77         set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
  78 }
  79
  80 static inline int ds1302_rxbit(void)
  81 {
  82         return !!(get_dp() & RTC_IODATA);
  83 }
  84
  85 #else
  86 #error "Add support for your platform"
  87 #endif
  88
  89 static void ds1302_sendbits(unsigned int val)
  90 {
  91         int i;
  92
  93         ds1302_set_tx();
  94
  95         for (i = 8; (i); i--, val >>= 1) {
  96                 ds1302_txbit(val & 0x1);
  97                 ds1302_clock();
  98         }
  99 }
 100
 101 static unsigned int ds1302_recvbits(void)
 102 {
 103         unsigned int val;
 104         int i;
 105
 106         ds1302_set_rx();
 107
 108         for (i = 0, val = 0; (i < 8); i++) {
 109                 val |= (ds1302_rxbit() << i);
 110                 ds1302_clock();
 111         }
 112
 113         return val;
 114 }
 115
 116 static unsigned int ds1302_readbyte(unsigned int addr)
 117 {
 118         unsigned int val;
 119
 120         ds1302_reset();
 121
 122         ds1302_start();
 123         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
 124         val = ds1302_recvbits();
 125         ds1302_stop();
 126
 127         return val;
 128 }
 129
 130 static void ds1302_writebyte(unsigned int addr, unsigned int val)
 131 {
 132         ds1302_reset();
 133
 134         ds1302_start();
 135         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
 136         ds1302_sendbits(val);
 137         ds1302_stop();
 138 }
 139
 140 static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
 141 {
 142         tm->tm_sec      = bcd2bin(ds1302_readbyte(RTC_ADDR_SEC));
 143         tm->tm_min      = bcd2bin(ds1302_readbyte(RTC_ADDR_MIN));
 144         tm->tm_hour     = bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR));
 145         tm->tm_wday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DAY));
 146         tm->tm_mday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DATE));
 147         tm->tm_mon      = bcd2bin(ds1302_readbyte(RTC_ADDR_MON)) - 1;
 148         tm->tm_year     = bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR));
 149
 150         if (tm->tm_year < 70)
 151                 tm->tm_year += 100;
 152
 153         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 154                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 155                 __func__,
 156                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 157                 tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);
 158
 159         return rtc_valid_tm(tm);
 160 }
 161
 162 static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
 163 {
 164         /* Stop RTC */
 165         ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);
 166
 167         ds1302_writebyte(RTC_ADDR_SEC, bin2bcd(tm->tm_sec));
 168         ds1302_writebyte(RTC_ADDR_MIN, bin2bcd(tm->tm_min));
 169         ds1302_writebyte(RTC_ADDR_HOUR, bin2bcd(tm->tm_hour));
 170         ds1302_writebyte(RTC_ADDR_DAY, bin2bcd(tm->tm_wday));
 171         ds1302_writebyte(RTC_ADDR_DATE, bin2bcd(tm->tm_mday));
 172         ds1302_writebyte(RTC_ADDR_MON, bin2bcd(tm->tm_mon + 1));
 173         ds1302_writebyte(RTC_ADDR_YEAR, bin2bcd(tm->tm_year % 100));
 174
 175         /* Start RTC */
 176         ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);
 177
 178         return 0;
 179 }
 180
 181 static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
 182                             unsigned long arg)
 183 {
 184         switch (cmd) {
 185 #ifdef RTC_SET_CHARGE
 186         case RTC_SET_CHARGE:
 187         {
 188                 int tcs_val;
 189
 190                 if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
 191                         return -EFAULT;
 192
 193                 ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
 194                 return 0;
 195         }
 196 #endif
 197         }
 198
 199         return -ENOIOCTLCMD;
 200 }
 201
 202 static struct rtc_class_ops ds1302_rtc_ops = {
 203         .read_time      = ds1302_rtc_read_time,
 204         .set_time       = ds1302_rtc_set_time,
 205         .ioctl          = ds1302_rtc_ioctl,
 206 };
 207
 208 static int __init ds1302_rtc_probe(struct platform_device *pdev)
 209 {
 210         struct rtc_device *rtc;
 211
 212         if (ds1302_hw_init()) {
 213                 dev_err(&pdev->dev, "Failed to init communication channel");
 214                 return -EINVAL;
 215         }
 216
 217         /* Reset */
 218         ds1302_reset();
 219
 220         /* Write a magic value to the DS1302 RAM, and see if it sticks. */
 221         ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
 222         if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42) {
 223                 dev_err(&pdev->dev, "Failed to probe");
 224                 return -ENODEV;
 225         }
 226
 227         rtc = devm_rtc_device_register(&pdev->dev, "ds1302",
 228                                            &ds1302_rtc_ops, THIS_MODULE);
 229         if (IS_ERR(rtc))
 230                 return PTR_ERR(rtc);
 231
 232         platform_set_drvdata(pdev, rtc);
 233
 234         return 0;
 235 }
 236
 237 static int __exit ds1302_rtc_remove(struct platform_device *pdev)
 238 {
 239         platform_set_drvdata(pdev, NULL);
 240
 241         return 0;
 242 }
 243
 244 static struct platform_driver ds1302_platform_driver = {
 245         .driver         = {
 246                 .name   = DRV_NAME,
 247                 .owner  = THIS_MODULE,
 248         },
 249         .remove         = __exit_p(ds1302_rtc_remove),
 250 };
 251
 252 module_platform_driver_probe(ds1302_platform_driver, ds1302_rtc_probe);
 253
 254 MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
 255 MODULE_VERSION(DRV_VERSION);
 256 MODULE_AUTHOR("Paul Mundt, David McCullough");
 257 MODULE_LICENSE("GPL v2");