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_CMD_WRITE_ENABLE    0x00            /* Write enable */
  27 #define RTC_CMD_WRITE_DISABLE   0x80            /* Write disable */
  28
  29 #define RTC_ADDR_RAM0   0x20            /* Address of RAM0 */
  30 #define RTC_ADDR_TCR    0x08            /* Address of trickle charge register */
  31 #define RTC_ADDR_CTRL   0x07            /* Address of control register */
  32 #define RTC_ADDR_YEAR   0x06            /* Address of year register */
  33 #define RTC_ADDR_DAY    0x05            /* Address of day of week register */
  34 #define RTC_ADDR_MON    0x04            /* Address of month register */
  35 #define RTC_ADDR_DATE   0x03            /* Address of day of month register */
  36 #define RTC_ADDR_HOUR   0x02            /* Address of hour register */
  37 #define RTC_ADDR_MIN    0x01            /* Address of minute register */
  38 #define RTC_ADDR_SEC    0x00            /* Address of second register */
  39
  40 #ifdef CONFIG_SH_SECUREEDGE5410
  41 #include <asm/rtc.h>
  42 #include <mach/secureedge5410.h>
  43
  44 #define RTC_RESET       0x1000
  45 #define RTC_IODATA      0x0800
  46 #define RTC_SCLK        0x0400
  47
  48 #define set_dp(x)       SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
  49 #define get_dp()        SECUREEDGE_READ_IOPORT()
  50 #define ds1302_set_tx()
  51 #define ds1302_set_rx()
  52
  53 static inline int ds1302_hw_init(void)
  54 {
  55         return 0;
  56 }
  57
  58 static inline void ds1302_reset(void)
  59 {
  60         set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  61 }
  62
  63 static inline void ds1302_clock(void)
  64 {
  65         set_dp(get_dp() | RTC_SCLK);    /* clock high */
  66         set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
  67 }
  68
  69 static inline void ds1302_start(void)
  70 {
  71         set_dp(get_dp() | RTC_RESET);
  72 }
  73
  74 static inline void ds1302_stop(void)
  75 {
  76         set_dp(get_dp() & ~RTC_RESET);
  77 }
  78
  79 static inline void ds1302_txbit(int bit)
  80 {
  81         set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
  82 }
  83
  84 static inline int ds1302_rxbit(void)
  85 {
  86         return !!(get_dp() & RTC_IODATA);
  87 }
  88
  89 #else
  90 #error "Add support for your platform"
  91 #endif
  92
  93 static void ds1302_sendbits(unsigned int val)
  94 {
  95         int i;
  96
  97         ds1302_set_tx();
  98
  99         for (i = 8; (i); i--, val >>= 1) {
 100                 ds1302_txbit(val & 0x1);
 101                 ds1302_clock();
 102         }
 103 }
 104
 105 static unsigned int ds1302_recvbits(void)
 106 {
 107         unsigned int val;
 108         int i;
 109
 110         ds1302_set_rx();
 111
 112         for (i = 0, val = 0; (i < 8); i++) {
 113                 val |= (ds1302_rxbit() << i);
 114                 ds1302_clock();
 115         }
 116
 117         return val;
 118 }
 119
 120 static unsigned int ds1302_readbyte(unsigned int addr)
 121 {
 122         unsigned int val;
 123
 124         ds1302_reset();
 125
 126         ds1302_start();
 127         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
 128         val = ds1302_recvbits();
 129         ds1302_stop();
 130
 131         return val;
 132 }
 133
 134 static void ds1302_writebyte(unsigned int addr, unsigned int val)
 135 {
 136         ds1302_reset();
 137
 138         ds1302_start();
 139         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
 140         ds1302_sendbits(val);
 141         ds1302_stop();
 142 }
 143
 144 static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
 145 {
 146         tm->tm_sec      = bcd2bin(ds1302_readbyte(RTC_ADDR_SEC));
 147         tm->tm_min      = bcd2bin(ds1302_readbyte(RTC_ADDR_MIN));
 148         tm->tm_hour     = bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR));
 149         tm->tm_wday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DAY));
 150         tm->tm_mday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DATE));
 151         tm->tm_mon      = bcd2bin(ds1302_readbyte(RTC_ADDR_MON)) - 1;
 152         tm->tm_year     = bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR));
 153
 154         if (tm->tm_year < 70)
 155                 tm->tm_year += 100;
 156
 157         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 158                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 159                 __func__,
 160                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 161                 tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);
 162
 163         return rtc_valid_tm(tm);
 164 }
 165
 166 static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
 167 {
 168         ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_ENABLE);
 169         /* Stop RTC */
 170         ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);
 171
 172         ds1302_writebyte(RTC_ADDR_SEC, bin2bcd(tm->tm_sec));
 173         ds1302_writebyte(RTC_ADDR_MIN, bin2bcd(tm->tm_min));
 174         ds1302_writebyte(RTC_ADDR_HOUR, bin2bcd(tm->tm_hour));
 175         ds1302_writebyte(RTC_ADDR_DAY, bin2bcd(tm->tm_wday));
 176         ds1302_writebyte(RTC_ADDR_DATE, bin2bcd(tm->tm_mday));
 177         ds1302_writebyte(RTC_ADDR_MON, bin2bcd(tm->tm_mon + 1));
 178         ds1302_writebyte(RTC_ADDR_YEAR, bin2bcd(tm->tm_year % 100));
 179
 180         /* Start RTC */
 181         ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);
 182
 183         ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_DISABLE);
 184
 185         return 0;
 186 }
 187
 188 static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
 189                             unsigned long arg)
 190 {
 191         switch (cmd) {
 192 #ifdef RTC_SET_CHARGE
 193         case RTC_SET_CHARGE:
 194         {
 195                 int tcs_val;
 196
 197                 if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
 198                         return -EFAULT;
 199
 200                 ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
 201                 return 0;
 202         }
 203 #endif
 204         }
 205
 206         return -ENOIOCTLCMD;
 207 }
 208
 209 static struct rtc_class_ops ds1302_rtc_ops = {
 210         .read_time      = ds1302_rtc_read_time,
 211         .set_time       = ds1302_rtc_set_time,
 212         .ioctl          = ds1302_rtc_ioctl,
 213 };
 214
 215 static int __init ds1302_rtc_probe(struct platform_device *pdev)
 216 {
 217         struct rtc_device *rtc;
 218
 219         if (ds1302_hw_init()) {
 220                 dev_err(&pdev->dev, "Failed to init communication channel");
 221                 return -EINVAL;
 222         }
 223
 224         /* Reset */
 225         ds1302_reset();
 226
 227         /* Write a magic value to the DS1302 RAM, and see if it sticks. */
 228         ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
 229         if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42) {
 230                 dev_err(&pdev->dev, "Failed to probe");
 231                 return -ENODEV;
 232         }
 233
 234         rtc = devm_rtc_device_register(&pdev->dev, "ds1302",
 235                                            &ds1302_rtc_ops, THIS_MODULE);
 236         if (IS_ERR(rtc))
 237                 return PTR_ERR(rtc);
 238
 239         platform_set_drvdata(pdev, rtc);
 240
 241         return 0;
 242 }
 243
 244 static struct platform_driver ds1302_platform_driver = {
 245         .driver         = {
 246                 .name   = DRV_NAME,
 247         },
 248 };
 249
 250 module_platform_driver_probe(ds1302_platform_driver, ds1302_rtc_probe);
 251
 252 MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
 253 MODULE_VERSION(DRV_VERSION);
 254 MODULE_AUTHOR("Paul Mundt, David McCullough");
 255 MODULE_LICENSE("GPL v2");