drivers/rtc/rtc-ds3234.c

   1 /* drivers/rtc/rtc-ds3234.c
   2  *
   3  * Driver for Dallas Semiconductor (DS3234) SPI RTC with Integrated Crystal
   4  * and SRAM.
   5  *
   6  * Copyright (C) 2008 MIMOMax Wireless Ltd.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * Changelog:
  13  *
  14  * 07-May-2008: Dennis Aberilla <denzzzhome@yahoo.com>
  15  *              - Created based on the max6902 code. Only implements the
  16  *                date/time keeping functions; no SRAM yet.
  17  */
  18
  19 #include <linux/device.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/rtc.h>
  22 #include <linux/spi/spi.h>
  23 #include <linux/bcd.h>
  24
  25 #define DS3234_REG_SECONDS      0x00
  26 #define DS3234_REG_MINUTES      0x01
  27 #define DS3234_REG_HOURS        0x02
  28 #define DS3234_REG_DAY          0x03
  29 #define DS3234_REG_DATE         0x04
  30 #define DS3234_REG_MONTH        0x05
  31 #define DS3234_REG_YEAR         0x06
  32 #define DS3234_REG_CENTURY      (1 << 7) /* Bit 7 of the Month register */
  33
  34 #define DS3234_REG_CONTROL      0x0E
  35 #define DS3234_REG_CONT_STAT    0x0F
  36
  37 #undef DS3234_DEBUG
  38
  39 struct ds3234 {
  40         struct rtc_device *rtc;
  41         u8 buf[8]; /* Burst read: addr + 7 regs */
  42         u8 tx_buf[2];
  43         u8 rx_buf[2];
  44 };
  45
  46 static void ds3234_set_reg(struct device *dev, unsigned char address,
  47                                 unsigned char data)
  48 {
  49         struct spi_device *spi = to_spi_device(dev);
  50         unsigned char buf[2];
  51
  52         /* MSB must be '1' to indicate write */
  53         buf[0] = address | 0x80;
  54         buf[1] = data;
  55
  56         spi_write(spi, buf, 2);
  57 }
  58
  59 static int ds3234_get_reg(struct device *dev, unsigned char address,
  60                                 unsigned char *data)
  61 {
  62         struct spi_device *spi = to_spi_device(dev);
  63         struct ds3234 *chip = dev_get_drvdata(dev);
  64         struct spi_message message;
  65         struct spi_transfer xfer;
  66         int status;
  67
  68         if (!data)
  69                 return -EINVAL;
  70
  71         /* Build our spi message */
  72         spi_message_init(&message);
  73         memset(&xfer, 0, sizeof(xfer));
  74
  75         /* Address + dummy tx byte */
  76         xfer.len = 2;
  77         xfer.tx_buf = chip->tx_buf;
  78         xfer.rx_buf = chip->rx_buf;
  79
  80         chip->tx_buf[0] = address;
  81         chip->tx_buf[1] = 0xff;
  82
  83         spi_message_add_tail(&xfer, &message);
  84
  85         /* do the i/o */
  86         status = spi_sync(spi, &message);
  87         if (status == 0)
  88                 status = message.status;
  89         else
  90                 return status;
  91
  92         *data = chip->rx_buf[1];
  93
  94         return status;
  95 }
  96
  97 static int ds3234_get_datetime(struct device *dev, struct rtc_time *dt)
  98 {
  99         struct spi_device *spi = to_spi_device(dev);
 100         struct ds3234 *chip = dev_get_drvdata(dev);
 101         struct spi_message message;
 102         struct spi_transfer xfer;
 103         int status;
 104
 105         /* build the message */
 106         spi_message_init(&message);
 107         memset(&xfer, 0, sizeof(xfer));
 108         xfer.len = 1 + 7;       /* Addr + 7 registers */
 109         xfer.tx_buf = chip->buf;
 110         xfer.rx_buf = chip->buf;
 111         chip->buf[0] = 0x00;    /* Start address */
 112         spi_message_add_tail(&xfer, &message);
 113
 114         /* do the i/o */
 115         status = spi_sync(spi, &message);
 116         if (status == 0)
 117                 status = message.status;
 118         else
 119                 return status;
 120
 121         /* Seconds, Minutes, Hours, Day, Date, Month, Year */
 122         dt->tm_sec      = bcd2bin(chip->buf[1]);
 123         dt->tm_min      = bcd2bin(chip->buf[2]);
 124         dt->tm_hour     = bcd2bin(chip->buf[3] & 0x3f);
 125         dt->tm_wday     = bcd2bin(chip->buf[4]) - 1; /* 0 = Sun */
 126         dt->tm_mday     = bcd2bin(chip->buf[5]);
 127         dt->tm_mon      = bcd2bin(chip->buf[6] & 0x1f) - 1; /* 0 = Jan */
 128         dt->tm_year     = bcd2bin(chip->buf[7] & 0xff) + 100; /* Assume 20YY */
 129
 130 #ifdef DS3234_DEBUG
 131         dev_dbg(dev, "\n%s : Read RTC values\n", __func__);
 132         dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
 133         dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
 134         dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
 135         dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
 136         dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
 137         dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
 138         dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
 139 #endif
 140
 141         return 0;
 142 }
 143
 144 static int ds3234_set_datetime(struct device *dev, struct rtc_time *dt)
 145 {
 146 #ifdef DS3234_DEBUG
 147         dev_dbg(dev, "\n%s : Setting RTC values\n", __func__);
 148         dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
 149         dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
 150         dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
 151         dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
 152         dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
 153         dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
 154         dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
 155 #endif
 156
 157         ds3234_set_reg(dev, DS3234_REG_SECONDS, bin2bcd(dt->tm_sec));
 158         ds3234_set_reg(dev, DS3234_REG_MINUTES, bin2bcd(dt->tm_min));
 159         ds3234_set_reg(dev, DS3234_REG_HOURS, bin2bcd(dt->tm_hour) & 0x3f);
 160
 161         /* 0 = Sun */
 162         ds3234_set_reg(dev, DS3234_REG_DAY, bin2bcd(dt->tm_wday + 1));
 163         ds3234_set_reg(dev, DS3234_REG_DATE, bin2bcd(dt->tm_mday));
 164
 165         /* 0 = Jan */
 166         ds3234_set_reg(dev, DS3234_REG_MONTH, bin2bcd(dt->tm_mon + 1));
 167
 168         /* Assume 20YY although we just want to make sure not to go negative. */
 169         if (dt->tm_year > 100)
 170                 dt->tm_year -= 100;
 171
 172         ds3234_set_reg(dev, DS3234_REG_YEAR, bin2bcd(dt->tm_year));
 173
 174         return 0;
 175 }
 176
 177 static int ds3234_read_time(struct device *dev, struct rtc_time *tm)
 178 {
 179         return ds3234_get_datetime(dev, tm);
 180 }
 181
 182 static int ds3234_set_time(struct device *dev, struct rtc_time *tm)
 183 {
 184         return ds3234_set_datetime(dev, tm);
 185 }
 186
 187 static const struct rtc_class_ops ds3234_rtc_ops = {
 188         .read_time      = ds3234_read_time,
 189         .set_time       = ds3234_set_time,
 190 };
 191
 192 static int ds3234_probe(struct spi_device *spi)
 193 {
 194         struct rtc_device *rtc;
 195         unsigned char tmp;
 196         struct ds3234 *chip;
 197         int res;
 198
 199         rtc = rtc_device_register("ds3234",
 200                                 &spi->dev, &ds3234_rtc_ops, THIS_MODULE);
 201         if (IS_ERR(rtc))
 202                 return PTR_ERR(rtc);
 203
 204         spi->mode = SPI_MODE_3;
 205         spi->bits_per_word = 8;
 206         spi_setup(spi);
 207
 208         chip = kzalloc(sizeof(struct ds3234), GFP_KERNEL);
 209         if (!chip) {
 210                 rtc_device_unregister(rtc);
 211                 return -ENOMEM;
 212         }
 213         chip->rtc = rtc;
 214         dev_set_drvdata(&spi->dev, chip);
 215
 216         res = ds3234_get_reg(&spi->dev, DS3234_REG_SECONDS, &tmp);
 217         if (res) {
 218                 rtc_device_unregister(rtc);
 219                 return res;
 220         }
 221
 222         /* Control settings
 223          *
 224          * CONTROL_REG
 225          * BIT 7        6       5       4       3       2       1       0
 226          *     EOSC     BBSQW   CONV    RS2     RS1     INTCN   A2IE    A1IE
 227          *
 228          *     0        0       0       1       1       1       0       0
 229          *
 230          * CONTROL_STAT_REG
 231          * BIT 7        6       5       4       3       2       1       0
 232          *     OSF      BB32kHz CRATE1  CRATE0  EN32kHz BSY     A2F     A1F
 233          *
 234          *     1        0       0       0       1       0       0       0
 235          */
 236         ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
 237         ds3234_set_reg(&spi->dev, DS3234_REG_CONTROL, tmp & 0x1c);
 238
 239         ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
 240         ds3234_set_reg(&spi->dev, DS3234_REG_CONT_STAT, tmp & 0x88);
 241
 242         /* Print our settings */
 243         ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
 244         dev_info(&spi->dev, "Control Reg: 0x%02x\n", tmp);
 245
 246         ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
 247         dev_info(&spi->dev, "Ctrl/Stat Reg: 0x%02x\n", tmp);
 248
 249         return 0;
 250 }
 251
 252 static int __exit ds3234_remove(struct spi_device *spi)
 253 {
 254         struct ds3234 *chip = platform_get_drvdata(spi);
 255         struct rtc_device *rtc = chip->rtc;
 256
 257         if (rtc)
 258                 rtc_device_unregister(rtc);
 259
 260         kfree(chip);
 261
 262         return 0;
 263 }
 264
 265 static struct spi_driver ds3234_driver = {
 266         .driver = {
 267                 .name    = "ds3234",
 268                 .bus    = &spi_bus_type,
 269                 .owner  = THIS_MODULE,
 270         },
 271         .probe   = ds3234_probe,
 272         .remove = __devexit_p(ds3234_remove),
 273 };
 274
 275 static __init int ds3234_init(void)
 276 {
 277         printk(KERN_INFO "DS3234 SPI RTC Driver\n");
 278         return spi_register_driver(&ds3234_driver);
 279 }
 280 module_init(ds3234_init);
 281
 282 static __exit void ds3234_exit(void)
 283 {
 284         spi_unregister_driver(&ds3234_driver);
 285 }
 286 module_exit(ds3234_exit);
 287
 288 MODULE_DESCRIPTION("DS3234 SPI RTC driver");
 289 MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
 290 MODULE_LICENSE("GPL");