drivers/rtc/rtc-ds1302.c

   1 /****************************************************************************/
   2
   3 /*
   4  * drivers/rtc/rtc-ds1302.c -- DS1302 RTC code
   5  *
   6  *  Copyright (C) 2002  David McCullough <davidm@snapgear.com>
   7  *  Copyright (C) 2003  Paul Mundt <lethal@linux-sh.org>
   8  *  Copyright (C) 2006  Greg Ungerer <gerg@snapgear.com>
   9  *
  10  * Support for the DS1302 on some Snapgear SH based boards.
  11  */
  12
  13 /****************************************************************************/
  14
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/rtc.h>
  19 #include <linux/bcd.h>
  20 #include <linux/platform_device.h>
  21 #include <asm/io.h>
  22 #include <asm/snapgear.h>
  23
  24 /****************************************************************************/
  25 /*
  26  *      we need to implement a DS1302 driver here that can operate in
  27  *      conjunction with the builtin rtc driver which is already quite friendly
  28  */
  29 /*****************************************************************************/
  30
  31 #define RTC_CMD_READ    0x81            /* Read command */
  32 #define RTC_CMD_WRITE   0x80            /* Write command */
  33
  34 #define RTC_ADDR_YEAR   0x06            /* Address of year register */
  35 #define RTC_ADDR_DAY    0x05            /* Address of day of week register */
  36 #define RTC_ADDR_MON    0x04            /* Address of month register */
  37 #define RTC_ADDR_DATE   0x03            /* Address of day of month register */
  38 #define RTC_ADDR_HOUR   0x02            /* Address of hour register */
  39 #define RTC_ADDR_MIN    0x01            /* Address of minute register */
  40 #define RTC_ADDR_SEC    0x00            /* Address of second register */
  41
  42 #define RTC_RESET       0x1000
  43 #define RTC_IODATA      0x0800
  44 #define RTC_SCLK        0x0400
  45
  46 #define set_dirp(x)
  47 #define get_dirp(x) 0
  48 #define set_dp(x)       SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
  49 #define get_dp(x)       SECUREEDGE_READ_IOPORT()
  50
  51 static void ds1302_sendbits(unsigned int val)
  52 {
  53         int     i;
  54
  55         for (i = 8; (i); i--, val >>= 1) {
  56                 set_dp((get_dp() & ~RTC_IODATA) | ((val & 0x1) ? RTC_IODATA : 0));
  57                 set_dp(get_dp() | RTC_SCLK);    // clock high
  58                 set_dp(get_dp() & ~RTC_SCLK);   // clock low
  59         }
  60 }
  61
  62 static unsigned int ds1302_recvbits(void)
  63 {
  64         unsigned int    val;
  65         int             i;
  66
  67         for (i = 0, val = 0; (i < 8); i++) {
  68                 val |= (((get_dp() & RTC_IODATA) ? 1 : 0) << i);
  69                 set_dp(get_dp() | RTC_SCLK);    // clock high
  70                 set_dp(get_dp() & ~RTC_SCLK);   // clock low
  71         }
  72         return(val);
  73 }
  74
  75 static unsigned int ds1302_readbyte(unsigned int addr)
  76 {
  77         unsigned int    val;
  78         unsigned long   flags;
  79
  80         local_irq_save(flags);
  81         set_dirp(get_dirp() | RTC_RESET | RTC_IODATA | RTC_SCLK);
  82         set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  83
  84         set_dp(get_dp() | RTC_RESET);
  85         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
  86         set_dirp(get_dirp() & ~RTC_IODATA);
  87         val = ds1302_recvbits();
  88         set_dp(get_dp() & ~RTC_RESET);
  89         local_irq_restore(flags);
  90
  91         return(val);
  92 }
  93
  94 static void ds1302_writebyte(unsigned int addr, unsigned int val)
  95 {
  96         unsigned long   flags;
  97
  98         local_irq_save(flags);
  99         set_dirp(get_dirp() | RTC_RESET | RTC_IODATA | RTC_SCLK);
 100         set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
 101         set_dp(get_dp() | RTC_RESET);
 102         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
 103         ds1302_sendbits(val);
 104         set_dp(get_dp() & ~RTC_RESET);
 105         local_irq_restore(flags);
 106 }
 107
 108 static void ds1302_reset(void)
 109 {
 110         unsigned long   flags;
 111         /* Hardware dependant reset/init */
 112         local_irq_save(flags);
 113         set_dirp(get_dirp() | RTC_RESET | RTC_IODATA | RTC_SCLK);
 114         set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
 115         local_irq_restore(flags);
 116 }
 117
 118 /****************************************************************************/
 119
 120 static inline int bcd2bin(int val)
 121 {
 122         return BCD2BIN(val);
 123 }
 124
 125 static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
 126 {
 127         tm->tm_sec = bcd2bin(ds1302_readbyte(RTC_ADDR_SEC) & 0x7f);
 128         tm->tm_min = bcd2bin(ds1302_readbyte(RTC_ADDR_MIN) & 0x7f);
 129         tm->tm_hour = bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR) & 0x3f);
 130         tm->tm_wday = bcd2bin(ds1302_readbyte(RTC_ADDR_DAY) & 0x07) - 1;
 131         tm->tm_mday = bcd2bin(ds1302_readbyte(RTC_ADDR_DATE) & 0x3f);
 132         tm->tm_mon = bcd2bin(ds1302_readbyte(RTC_ADDR_MON) & 0x1f) - 1;
 133         tm->tm_year = bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR)) + 100;
 134
 135         return 0;
 136 }
 137
 138 static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
 139 {
 140         /* STOP RTC */
 141         ds1302_writebyte(RTC_ADDR_SEC, 0x80);
 142
 143         ds1302_writebyte(RTC_ADDR_MIN, BIN2BCD(tm->tm_min));
 144         ds1302_writebyte(RTC_ADDR_HOUR, BIN2BCD(tm->tm_hour));
 145         ds1302_writebyte(RTC_ADDR_DAY, BIN2BCD(tm->tm_wday + 1));
 146         ds1302_writebyte(RTC_ADDR_DATE, BIN2BCD(tm->tm_mday));
 147         ds1302_writebyte(RTC_ADDR_MON, BIN2BCD(tm->tm_mon + 1));
 148         ds1302_writebyte(RTC_ADDR_YEAR, BIN2BCD(tm->tm_year - 100));
 149
 150         /* RESTARTS RTC */
 151         ds1302_writebyte(RTC_ADDR_SEC, BIN2BCD(tm->tm_sec));
 152
 153         return 0;
 154 }
 155
 156 /****************************************************************************/
 157
 158 static struct rtc_class_ops ds1302_rtc_ops = {
 159         .read_time      = ds1302_rtc_read_time,
 160         .set_time       = ds1302_rtc_set_time,
 161 };
 162
 163 /****************************************************************************/
 164
 165 static int __devinit ds1302_rtc_probe(struct platform_device *pdev)
 166 {
 167         struct rtc_device *rdev;
 168         unsigned char *test = "snapgear";
 169         int i;
 170
 171         ds1302_reset();
 172
 173         for (i = 0; test[i]; i++)
 174                 ds1302_writebyte(32 + i, test[i]);
 175
 176         for (i = 0; test[i]; i++) {
 177                 if (ds1302_readbyte(32 + i) != test[i])
 178                         return -ENOENT;
 179         }
 180
 181         rdev = rtc_device_register("ds1302", &pdev->dev, &ds1302_rtc_ops, THIS_MODULE);
 182
 183         printk("SnapGear RTC: using ds1302 rtc.\n");
 184
 185         platform_set_drvdata(pdev, rdev);
 186         return 0;
 187 }
 188
 189 /****************************************************************************/
 190
 191 static int __devexit ds1302_rtc_remove(struct platform_device *pdev)
 192 {
 193         struct rtc_device *rdev = platform_get_drvdata(pdev);
 194
 195         if (rdev)
 196                 rtc_device_unregister(rdev);
 197         return 0;
 198 }
 199
 200 /****************************************************************************/
 201
 202 static struct platform_driver ds1302_rtc_platform_driver = {
 203         .driver         = {
 204                 .name   = "ds1302",
 205                 .owner  = THIS_MODULE,
 206         },
 207         .probe          = ds1302_rtc_probe,
 208         .remove         = __devexit_p(ds1302_rtc_remove),
 209 };
 210
 211 /****************************************************************************/
 212
 213 static int __init ds1302_rtc_init(void)
 214 {
 215         return platform_driver_register(&ds1302_rtc_platform_driver);
 216 }
 217
 218 static void __exit ds1302_rtc_exit(void)
 219 {
 220         platform_driver_unregister(&ds1302_rtc_platform_driver);
 221 }
 222
 223 /****************************************************************************/
 224
 225 module_init(ds1302_rtc_init);
 226 module_exit(ds1302_rtc_exit);
 227
 228 /****************************************************************************/
 229
 230 MODULE_DESCRIPTION("DS1302 on SnapGear SH hardware platforms");
 231 MODULE_AUTHOR("David McCullough <davidm@snapgear.com>, Paul Mundt <lethal@linux-sh.org>, Greg Ungerer <gerg@snapgear.com>");
 232 MODULE_LICENSE("GPL");
 233
 234 /****************************************************************************/