linux/drivers/rtc/rtc-r9701.c
<<
>>
Prefs
   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        unsigned char tmp;
 126        int res;
 127
 128        tmp = R100CNT;
 129        res = read_regs(&spi->dev, &tmp, 1);
 130        if (res || tmp != 0x20) {
 131                dev_err(&spi->dev, "cannot read RTC register\n");
 132                return -ENODEV;
 133        }
 134
 135        rtc = rtc_device_register("r9701",
 136                                &spi->dev, &r9701_rtc_ops, THIS_MODULE);
 137        if (IS_ERR(rtc))
 138                return PTR_ERR(rtc);
 139
 140        dev_set_drvdata(&spi->dev, rtc);
 141
 142        return 0;
 143}
 144
 145static int __devexit r9701_remove(struct spi_device *spi)
 146{
 147        struct rtc_device *rtc = dev_get_drvdata(&spi->dev);
 148
 149        rtc_device_unregister(rtc);
 150        return 0;
 151}
 152
 153static struct spi_driver r9701_driver = {
 154        .driver = {
 155                .name   = "rtc-r9701",
 156                .owner  = THIS_MODULE,
 157        },
 158        .probe  = r9701_probe,
 159        .remove = __devexit_p(r9701_remove),
 160};
 161
 162static __init int r9701_init(void)
 163{
 164        return spi_register_driver(&r9701_driver);
 165}
 166module_init(r9701_init);
 167
 168static __exit void r9701_exit(void)
 169{
 170        spi_unregister_driver(&r9701_driver);
 171}
 172module_exit(r9701_exit);
 173
 174MODULE_DESCRIPTION("r9701 spi RTC driver");
 175MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
 176MODULE_LICENSE("GPL");
 177MODULE_ALIAS("spi:rtc-r9701");
 178