drivers/rtc/rtc-ds1390.c

   1 /*
   2  * rtc-ds1390.c -- driver for DS1390/93/94
   3  *
   4  * Copyright (C) 2008 Mercury IMC Ltd
   5  * Written by Mark Jackson <mpfj@mimc.co.uk>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * NOTE : Currently this driver only supports the bare minimum for read
  12  * and write the RTC.  The extra features provided by the chip family
  13  * (alarms, trickle charger, different control registers) are unavailable.
  14  */
  15
  16 #include <linux/platform_device.h>
  17 #include <linux/rtc.h>
  18 #include <linux/spi/spi.h>
  19 #include <linux/bcd.h>
  20
  21 #define DS1390_REG_100THS               0x00
  22 #define DS1390_REG_SECONDS              0x01
  23 #define DS1390_REG_MINUTES              0x02
  24 #define DS1390_REG_HOURS                0x03
  25 #define DS1390_REG_DAY                  0x04
  26 #define DS1390_REG_DATE                 0x05
  27 #define DS1390_REG_MONTH_CENT           0x06
  28 #define DS1390_REG_YEAR                 0x07
  29
  30 #define DS1390_REG_ALARM_100THS         0x08
  31 #define DS1390_REG_ALARM_SECONDS        0x09
  32 #define DS1390_REG_ALARM_MINUTES        0x0A
  33 #define DS1390_REG_ALARM_HOURS          0x0B
  34 #define DS1390_REG_ALARM_DAY_DATE       0x0C
  35
  36 #define DS1390_REG_CONTROL              0x0D
  37 #define DS1390_REG_STATUS               0x0E
  38 #define DS1390_REG_TRICKLE              0x0F
  39
  40 struct ds1390 {
  41         struct rtc_device *rtc;
  42         u8 txrx_buf[9]; /* cmd + 8 registers */
  43 };
  44
  45 static void ds1390_set_reg(struct device *dev, unsigned char address,
  46                                 unsigned char data)
  47 {
  48         struct spi_device *spi = to_spi_device(dev);
  49         struct ds1390 *chip = dev_get_drvdata(dev);
  50
  51         /* Set MSB to indicate write */
  52         chip->txrx_buf[0] = address | 0x80;
  53         chip->txrx_buf[1] = data;
  54
  55         /* do the i/o */
  56         spi_write_then_read(spi, chip->txrx_buf, 2, NULL, 0);
  57 }
  58
  59 static int ds1390_get_reg(struct device *dev, unsigned char address,
  60                                 unsigned char *data)
  61 {
  62         struct spi_device *spi = to_spi_device(dev);
  63         struct ds1390 *chip = dev_get_drvdata(dev);
  64         int status;
  65
  66         if (!data)
  67                 return -EINVAL;
  68
  69         /* Clear MSB to indicate read */
  70         chip->txrx_buf[0] = address & 0x7f;
  71         /* do the i/o */
  72         status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);
  73         if (status != 0)
  74                 return status;
  75
  76         *data = chip->txrx_buf[1];
  77
  78         return 0;
  79 }
  80
  81 static int ds1390_get_datetime(struct device *dev, struct rtc_time *dt)
  82 {
  83         struct spi_device *spi = to_spi_device(dev);
  84         struct ds1390 *chip = dev_get_drvdata(dev);
  85         int status;
  86
  87         /* build the message */
  88         chip->txrx_buf[0] = DS1390_REG_SECONDS;
  89
  90         /* do the i/o */
  91         status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8);
  92         if (status != 0)
  93                 return status;
  94
  95         /* The chip sends data in this order:
  96          * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */
  97         dt->tm_sec      = bcd2bin(chip->txrx_buf[0]);
  98         dt->tm_min      = bcd2bin(chip->txrx_buf[1]);
  99         dt->tm_hour     = bcd2bin(chip->txrx_buf[2]);
 100         dt->tm_wday     = bcd2bin(chip->txrx_buf[3]);
 101         dt->tm_mday     = bcd2bin(chip->txrx_buf[4]);
 102         /* mask off century bit */
 103         dt->tm_mon      = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1;
 104         /* adjust for century bit */
 105         dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0);
 106
 107         return rtc_valid_tm(dt);
 108 }
 109
 110 static int ds1390_set_datetime(struct device *dev, struct rtc_time *dt)
 111 {
 112         struct spi_device *spi = to_spi_device(dev);
 113         struct ds1390 *chip = dev_get_drvdata(dev);
 114
 115         /* build the message */
 116         chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80;
 117         chip->txrx_buf[1] = bin2bcd(dt->tm_sec);
 118         chip->txrx_buf[2] = bin2bcd(dt->tm_min);
 119         chip->txrx_buf[3] = bin2bcd(dt->tm_hour);
 120         chip->txrx_buf[4] = bin2bcd(dt->tm_wday);
 121         chip->txrx_buf[5] = bin2bcd(dt->tm_mday);
 122         chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) |
 123                                 ((dt->tm_year > 99) ? 0x80 : 0x00);
 124         chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100);
 125
 126         /* do the i/o */
 127         return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0);
 128 }
 129
 130 static int ds1390_read_time(struct device *dev, struct rtc_time *tm)
 131 {
 132         return ds1390_get_datetime(dev, tm);
 133 }
 134
 135 static int ds1390_set_time(struct device *dev, struct rtc_time *tm)
 136 {
 137         return ds1390_set_datetime(dev, tm);
 138 }
 139
 140 static const struct rtc_class_ops ds1390_rtc_ops = {
 141         .read_time      = ds1390_read_time,
 142         .set_time       = ds1390_set_time,
 143 };
 144
 145 static int __devinit ds1390_probe(struct spi_device *spi)
 146 {
 147         struct rtc_device *rtc;
 148         unsigned char tmp;
 149         struct ds1390 *chip;
 150         int res;
 151
 152         printk(KERN_DEBUG "DS1390 SPI RTC driver\n");
 153
 154         rtc = rtc_device_register("ds1390",
 155                                 &spi->dev, &ds1390_rtc_ops, THIS_MODULE);
 156         if (IS_ERR(rtc)) {
 157                 printk(KERN_ALERT "RTC : unable to register device\n");
 158                 return PTR_ERR(rtc);
 159         }
 160
 161         spi->mode = SPI_MODE_3;
 162         spi->bits_per_word = 8;
 163         spi_setup(spi);
 164
 165         chip = kzalloc(sizeof *chip, GFP_KERNEL);
 166         if (!chip) {
 167                 printk(KERN_ALERT "RTC : unable to allocate device memory\n");
 168                 rtc_device_unregister(rtc);
 169                 return -ENOMEM;
 170         }
 171         chip->rtc = rtc;
 172         dev_set_drvdata(&spi->dev, chip);
 173
 174         res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);
 175         if (res) {
 176                 printk(KERN_ALERT "RTC : unable to read device\n");
 177                 rtc_device_unregister(rtc);
 178                 return res;
 179         }
 180
 181         return 0;
 182 }
 183
 184 static int __devexit ds1390_remove(struct spi_device *spi)
 185 {
 186         struct ds1390 *chip = platform_get_drvdata(spi);
 187         struct rtc_device *rtc = chip->rtc;
 188
 189         if (rtc)
 190                 rtc_device_unregister(rtc);
 191
 192         kfree(chip);
 193
 194         return 0;
 195 }
 196
 197 static struct spi_driver ds1390_driver = {
 198         .driver = {
 199                 .name   = "rtc-ds1390",
 200                 .owner  = THIS_MODULE,
 201         },
 202         .probe  = ds1390_probe,
 203         .remove = __devexit_p(ds1390_remove),
 204 };
 205
 206 static __init int ds1390_init(void)
 207 {
 208         return spi_register_driver(&ds1390_driver);
 209 }
 210 module_init(ds1390_init);
 211
 212 static __exit void ds1390_exit(void)
 213 {
 214         spi_unregister_driver(&ds1390_driver);
 215 }
 216 module_exit(ds1390_exit);
 217
 218 MODULE_DESCRIPTION("DS1390/93/94 SPI RTC driver");
 219 MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>");
 220 MODULE_LICENSE("GPL");