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_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
  53static inline int ds1302_hw_init(void)
  54{
  55        return 0;
  56}
  57
  58static inline void ds1302_reset(void)
  59{
  60        set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  61}
  62
  63static 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
  69static inline void ds1302_start(void)
  70{
  71        set_dp(get_dp() | RTC_RESET);
  72}
  73
  74static inline void ds1302_stop(void)
  75{
  76        set_dp(get_dp() & ~RTC_RESET);
  77}
  78
  79static inline void ds1302_txbit(int bit)
  80{
  81        set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
  82}
  83
  84static 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
  93static 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
 105static 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
 120static 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
 134static 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
 144static 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
 166static 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
 188static 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
 209static 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
 215static 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
 244static struct platform_driver ds1302_platform_driver = {
 245        .driver         = {
 246                .name   = DRV_NAME,
 247                .owner  = THIS_MODULE,
 248        },
 249};
 250
 251module_platform_driver_probe(ds1302_platform_driver, ds1302_rtc_probe);
 252
 253MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
 254MODULE_VERSION(DRV_VERSION);
 255MODULE_AUTHOR("Paul Mundt, David McCullough");
 256MODULE_LICENSE("GPL v2");
 257
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