linux/drivers/rtc/rtc-r9701.c
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   1/*
   2 * Driver for Epson RTC-9701JE
   3 *
   4 * Copyright (C) 2008 Magnus Damm
   5 *
   6 * Based on rtc-max6902.c
   7 *
   8 * Copyright (C) 2006 8D Technologies inc.
   9 * Copyright (C) 2004 Compulab Ltd.
  10 *
  11 * This program is free software; you can redistribute it and/or modify
  12 * it under the terms of the GNU General Public License version 2 as
  13 * published by the Free Software Foundation.
  14 */
  15
  16#include <linux/module.h>
  17#include <linux/kernel.h>
  18#include <linux/platform_device.h>
  19#include <linux/device.h>
  20#include <linux/init.h>
  21#include <linux/rtc.h>
  22#include <linux/spi/spi.h>
  23#include <linux/bcd.h>
  24#include <linux/delay.h>
  25#include <linux/bitops.h>
  26
  27#define RSECCNT 0x00    /* Second Counter */
  28#define RMINCNT 0x01    /* Minute Counter */
  29#define RHRCNT  0x02    /* Hour Counter */
  30#define RWKCNT  0x03    /* Week Counter */
  31#define RDAYCNT 0x04    /* Day Counter */
  32#define RMONCNT 0x05    /* Month Counter */
  33#define RYRCNT  0x06    /* Year Counter */
  34#define R100CNT 0x07    /* Y100 Counter */
  35#define RMINAR  0x08    /* Minute Alarm */
  36#define RHRAR   0x09    /* Hour Alarm */
  37#define RWKAR   0x0a    /* Week/Day Alarm */
  38#define RTIMCNT 0x0c    /* Interval Timer */
  39#define REXT    0x0d    /* Extension Register */
  40#define RFLAG   0x0e    /* RTC Flag Register */
  41#define RCR     0x0f    /* RTC Control Register */
  42
  43static int write_reg(struct device *dev, int address, unsigned char data)
  44{
  45        struct spi_device *spi = to_spi_device(dev);
  46        unsigned char buf[2];
  47
  48        buf[0] = address & 0x7f;
  49        buf[1] = data;
  50
  51        return spi_write(spi, buf, ARRAY_SIZE(buf));
  52}
  53
  54static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
  55{
  56        struct spi_device *spi = to_spi_device(dev);
  57        u8 txbuf[1], rxbuf[1];
  58        int k, ret;
  59
  60        ret = 0;
  61
  62        for (k = 0; ret == 0 && k < no_regs; k++) {
  63                txbuf[0] = 0x80 | regs[k];
  64                ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
  65                regs[k] = rxbuf[0];
  66        }
  67
  68        return ret;
  69}
  70
  71static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
  72{
  73        int ret;
  74        unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
  75                                RDAYCNT, RMONCNT, RYRCNT };
  76
  77        ret = read_regs(dev, buf, ARRAY_SIZE(buf));
  78        if (ret)
  79                return ret;
  80
  81        memset(dt, 0, sizeof(*dt));
  82
  83        dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
  84        dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
  85        dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
  86
  87        dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
  88        dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
  89        dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
  90
  91        /* the rtc device may contain illegal values on power up
  92         * according to the data sheet. make sure they are valid.
  93         */
  94
  95        return rtc_valid_tm(dt);
  96}
  97
  98static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
  99{
 100        int ret, year;
 101
 102        year = dt->tm_year + 1900;
 103        if (year >= 2100 || year < 2000)
 104                return -EINVAL;
 105
 106        ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
 107        ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
 108        ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
 109        ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
 110        ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
 111        ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
 112        ret = ret ? ret : write_reg(dev, RWKCNT, 1 << dt->tm_wday);
 113
 114        return ret;
 115}
 116
 117static const struct rtc_class_ops r9701_rtc_ops = {
 118        .read_time      = r9701_get_datetime,
 119        .set_time       = r9701_set_datetime,
 120};
 121
 122static int __devinit r9701_probe(struct spi_device *spi)
 123{
 124        struct rtc_device *rtc;
 125        struct rtc_time dt;
 126        unsigned char tmp;
 127        int res;
 128
 129        tmp = R100CNT;
 130        res = read_regs(&spi->dev, &tmp, 1);
 131        if (res || tmp != 0x20) {
 132                dev_err(&spi->dev, "cannot read RTC register\n");
 133                return -ENODEV;
 134        }
 135
 136        /*
 137         * The device seems to be present. Now check if the registers
 138         * contain invalid values. If so, try to write a default date:
 139         * 2000/1/1 00:00:00
 140         */
 141        if (r9701_get_datetime(&spi->dev, &dt)) {
 142                dev_info(&spi->dev, "trying to repair invalid date/time\n");
 143                dt.tm_sec  = 0;
 144                dt.tm_min  = 0;
 145                dt.tm_hour = 0;
 146                dt.tm_mday = 1;
 147                dt.tm_mon  = 0;
 148                dt.tm_year = 100;
 149
 150                if (r9701_set_datetime(&spi->dev, &dt) ||
 151                                r9701_get_datetime(&spi->dev, &dt)) {
 152                        dev_err(&spi->dev, "cannot repair RTC register\n");
 153                        return -ENODEV;
 154                }
 155        }
 156
 157        rtc = rtc_device_register("r9701",
 158                                &spi->dev, &r9701_rtc_ops, THIS_MODULE);
 159        if (IS_ERR(rtc))
 160                return PTR_ERR(rtc);
 161
 162        dev_set_drvdata(&spi->dev, rtc);
 163
 164        return 0;
 165}
 166
 167static int __devexit r9701_remove(struct spi_device *spi)
 168{
 169        struct rtc_device *rtc = dev_get_drvdata(&spi->dev);
 170
 171        rtc_device_unregister(rtc);
 172        return 0;
 173}
 174
 175static struct spi_driver r9701_driver = {
 176        .driver = {
 177                .name   = "rtc-r9701",
 178                .owner  = THIS_MODULE,
 179        },
 180        .probe  = r9701_probe,
 181        .remove = __devexit_p(r9701_remove),
 182};
 183
 184module_spi_driver(r9701_driver);
 185
 186MODULE_DESCRIPTION("r9701 spi RTC driver");
 187MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
 188MODULE_LICENSE("GPL");
 189MODULE_ALIAS("spi:rtc-r9701");
 190
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