drivers/rtc/rtc-r9701.c

   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/version.h>
  18 #include <linux/kernel.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/device.h>
  21 #include <linux/init.h>
  22 #include <linux/rtc.h>
  23 #include <linux/spi/spi.h>
  24 #include <linux/bcd.h>
  25 #include <linux/delay.h>
  26 #include <linux/bitops.h>
  27
  28 #define RSECCNT 0x00    /* Second Counter */
  29 #define RMINCNT 0x01    /* Minute Counter */
  30 #define RHRCNT  0x02    /* Hour Counter */
  31 #define RWKCNT  0x03    /* Week Counter */
  32 #define RDAYCNT 0x04    /* Day Counter */
  33 #define RMONCNT 0x05    /* Month Counter */
  34 #define RYRCNT  0x06    /* Year Counter */
  35 #define R100CNT 0x07    /* Y100 Counter */
  36 #define RMINAR  0x08    /* Minute Alarm */
  37 #define RHRAR   0x09    /* Hour Alarm */
  38 #define RWKAR   0x0a    /* Week/Day Alarm */
  39 #define RTIMCNT 0x0c    /* Interval Timer */
  40 #define REXT    0x0d    /* Extension Register */
  41 #define RFLAG   0x0e    /* RTC Flag Register */
  42 #define RCR     0x0f    /* RTC Control Register */
  43
  44 static int write_reg(struct device *dev, int address, unsigned char data)
  45 {
  46         struct spi_device *spi = to_spi_device(dev);
  47         unsigned char buf[2];
  48
  49         buf[0] = address & 0x7f;
  50         buf[1] = data;
  51
  52         return spi_write(spi, buf, ARRAY_SIZE(buf));
  53 }
  54
  55 static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
  56 {
  57         struct spi_device *spi = to_spi_device(dev);
  58         u8 txbuf[1], rxbuf[1];
  59         int k, ret;
  60
  61         ret = 0;
  62
  63         for (k = 0; ret == 0 && k < no_regs; k++) {
  64                 txbuf[0] = 0x80 | regs[k];
  65                 ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
  66                 regs[k] = rxbuf[0];
  67         }
  68
  69         return ret;
  70 }
  71
  72 static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
  73 {
  74         int ret;
  75         unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
  76                                 RDAYCNT, RMONCNT, RYRCNT };
  77
  78         ret = read_regs(dev, buf, ARRAY_SIZE(buf));
  79         if (ret)
  80                 return ret;
  81
  82         memset(dt, 0, sizeof(*dt));
  83
  84         dt->tm_sec = BCD2BIN(buf[0]); /* RSECCNT */
  85         dt->tm_min = BCD2BIN(buf[1]); /* RMINCNT */
  86         dt->tm_hour = BCD2BIN(buf[2]); /* RHRCNT */
  87
  88         dt->tm_mday = BCD2BIN(buf[3]); /* RDAYCNT */
  89         dt->tm_mon = BCD2BIN(buf[4]) - 1; /* RMONCNT */
  90         dt->tm_year = BCD2BIN(buf[5]) + 100; /* RYRCNT */
  91
  92         /* the rtc device may contain illegal values on power up
  93          * according to the data sheet. make sure they are valid.
  94          */
  95
  96         return rtc_valid_tm(dt);
  97 }
  98
  99 static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
 100 {
 101         int ret, year;
 102
 103         year = dt->tm_year + 1900;
 104         if (year >= 2100 || year < 2000)
 105                 return -EINVAL;
 106
 107         ret = write_reg(dev, RHRCNT, BIN2BCD(dt->tm_hour));
 108         ret = ret ? ret : write_reg(dev, RMINCNT, BIN2BCD(dt->tm_min));
 109         ret = ret ? ret : write_reg(dev, RSECCNT, BIN2BCD(dt->tm_sec));
 110         ret = ret ? ret : write_reg(dev, RDAYCNT, BIN2BCD(dt->tm_mday));
 111         ret = ret ? ret : write_reg(dev, RMONCNT, BIN2BCD(dt->tm_mon + 1));
 112         ret = ret ? ret : write_reg(dev, RYRCNT, BIN2BCD(dt->tm_year - 100));
 113         ret = ret ? ret : write_reg(dev, RWKCNT, 1 << dt->tm_wday);
 114
 115         return ret;
 116 }
 117
 118 static const struct rtc_class_ops r9701_rtc_ops = {
 119         .read_time      = r9701_get_datetime,
 120         .set_time       = r9701_set_datetime,
 121 };
 122
 123 static int __devinit r9701_probe(struct spi_device *spi)
 124 {
 125         struct rtc_device *rtc;
 126         unsigned char tmp;
 127         int res;
 128
 129         rtc = rtc_device_register("r9701",
 130                                 &spi->dev, &r9701_rtc_ops, THIS_MODULE);
 131         if (IS_ERR(rtc))
 132                 return PTR_ERR(rtc);
 133
 134         dev_set_drvdata(&spi->dev, rtc);
 135
 136         tmp = R100CNT;
 137         res = read_regs(&spi->dev, &tmp, 1);
 138         if (res || tmp != 0x20) {
 139                 rtc_device_unregister(rtc);
 140                 return res;
 141         }
 142
 143         return 0;
 144 }
 145
 146 static int __devexit r9701_remove(struct spi_device *spi)
 147 {
 148         struct rtc_device *rtc = dev_get_drvdata(&spi->dev);
 149
 150         rtc_device_unregister(rtc);
 151         return 0;
 152 }
 153
 154 static struct spi_driver r9701_driver = {
 155         .driver = {
 156                 .name   = "rtc-r9701",
 157                 .owner  = THIS_MODULE,
 158         },
 159         .probe  = r9701_probe,
 160         .remove = __devexit_p(r9701_remove),
 161 };
 162
 163 static __init int r9701_init(void)
 164 {
 165         return spi_register_driver(&r9701_driver);
 166 }
 167 module_init(r9701_init);
 168
 169 static __exit void r9701_exit(void)
 170 {
 171         spi_unregister_driver(&r9701_driver);
 172 }
 173 module_exit(r9701_exit);
 174
 175 MODULE_DESCRIPTION("r9701 spi RTC driver");
 176 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
 177 MODULE_LICENSE("GPL");