linux/drivers/rtc/rtc-ds1302.c
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   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
  49static inline int ds1302_hw_init(void)
  50{
  51        return 0;
  52}
  53
  54static inline void ds1302_reset(void)
  55{
  56        set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  57}
  58
  59static 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
  65static inline void ds1302_start(void)
  66{
  67        set_dp(get_dp() | RTC_RESET);
  68}
  69
  70static inline void ds1302_stop(void)
  71{
  72        set_dp(get_dp() & ~RTC_RESET);
  73}
  74
  75static inline void ds1302_txbit(int bit)
  76{
  77        set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
  78}
  79
  80static 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
  89static 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
 101static 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
 116static 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
 130static 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
 140static 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
 162static 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
 181static 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
 202static 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
 208static 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 = rtc_device_register("ds1302", &pdev->dev,
 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
 237static int __devexit ds1302_rtc_remove(struct platform_device *pdev)
 238{
 239        struct rtc_device *rtc = platform_get_drvdata(pdev);
 240
 241        rtc_device_unregister(rtc);
 242        platform_set_drvdata(pdev, NULL);
 243
 244        return 0;
 245}
 246
 247static struct platform_driver ds1302_platform_driver = {
 248        .driver         = {
 249                .name   = DRV_NAME,
 250                .owner  = THIS_MODULE,
 251        },
 252        .remove         = __devexit_p(ds1302_rtc_remove),
 253};
 254
 255static int __init ds1302_rtc_init(void)
 256{
 257        return platform_driver_probe(&ds1302_platform_driver, ds1302_rtc_probe);
 258}
 259
 260static void __exit ds1302_rtc_exit(void)
 261{
 262        platform_driver_unregister(&ds1302_platform_driver);
 263}
 264
 265module_init(ds1302_rtc_init);
 266module_exit(ds1302_rtc_exit);
 267
 268MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
 269MODULE_VERSION(DRV_VERSION);
 270MODULE_AUTHOR("Paul Mundt, David McCullough");
 271MODULE_LICENSE("GPL v2");
 272
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