drivers/rtc/rtc-max6902.c

   1 /* drivers/rtc/rtc-max6902.c
   2  *
   3  * Copyright (C) 2006 8D Technologies inc.
   4  * Copyright (C) 2004 Compulab Ltd.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Driver for MAX6902 spi RTC
  11  *
  12  * Changelog:
  13  *
  14  * 24-May-2006: Raphael Assenat <raph@8d.com>
  15  *                - Major rework
  16  *                              Converted to rtc_device and uses the SPI layer.
  17  *
  18  * ??-???-2005: Someone at Compulab
  19  *                - Initial driver creation.
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/kernel.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/init.h>
  26 #include <linux/rtc.h>
  27 #include <linux/spi/spi.h>
  28 #include <linux/bcd.h>
  29 #include <linux/delay.h>
  30
  31 #define MAX6902_REG_SECONDS             0x01
  32 #define MAX6902_REG_MINUTES             0x03
  33 #define MAX6902_REG_HOURS               0x05
  34 #define MAX6902_REG_DATE                0x07
  35 #define MAX6902_REG_MONTH               0x09
  36 #define MAX6902_REG_DAY                 0x0B
  37 #define MAX6902_REG_YEAR                0x0D
  38 #define MAX6902_REG_CONTROL             0x0F
  39 #define MAX6902_REG_CENTURY             0x13
  40
  41 #undef MAX6902_DEBUG
  42
  43 struct max6902 {
  44         struct rtc_device *rtc;
  45         u8 buf[9]; /* Burst read cmd + 8 registers */
  46         u8 tx_buf[2];
  47         u8 rx_buf[2];
  48 };
  49
  50 static void max6902_set_reg(struct device *dev, unsigned char address,
  51                                 unsigned char data)
  52 {
  53         struct spi_device *spi = to_spi_device(dev);
  54         unsigned char buf[2];
  55
  56         /* MSB must be '0' to write */
  57         buf[0] = address & 0x7f;
  58         buf[1] = data;
  59
  60         spi_write(spi, buf, 2);
  61 }
  62
  63 static int max6902_get_reg(struct device *dev, unsigned char address,
  64                                 unsigned char *data)
  65 {
  66         struct spi_device *spi = to_spi_device(dev);
  67         struct max6902 *chip = dev_get_drvdata(dev);
  68         struct spi_message message;
  69         struct spi_transfer xfer;
  70         int status;
  71
  72         if (!data)
  73                 return -EINVAL;
  74
  75         /* Build our spi message */
  76         spi_message_init(&message);
  77         memset(&xfer, 0, sizeof(xfer));
  78         xfer.len = 2;
  79         /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */
  80         xfer.tx_buf = chip->tx_buf;
  81         xfer.rx_buf = chip->rx_buf;
  82
  83         /* Set MSB to indicate read */
  84         chip->tx_buf[0] = address | 0x80;
  85
  86         spi_message_add_tail(&xfer, &message);
  87
  88         /* do the i/o */
  89         status = spi_sync(spi, &message);
  90
  91         if (status == 0)
  92                 *data = chip->rx_buf[1];
  93         return status;
  94 }
  95
  96 static int max6902_get_datetime(struct device *dev, struct rtc_time *dt)
  97 {
  98         unsigned char tmp;
  99         int century;
 100         int err;
 101         struct spi_device *spi = to_spi_device(dev);
 102         struct max6902 *chip = dev_get_drvdata(dev);
 103         struct spi_message message;
 104         struct spi_transfer xfer;
 105         int status;
 106
 107         err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp);
 108         if (err)
 109                 return err;
 110
 111         /* build the message */
 112         spi_message_init(&message);
 113         memset(&xfer, 0, sizeof(xfer));
 114         xfer.len = 1 + 7;       /* Burst read command + 7 registers */
 115         xfer.tx_buf = chip->buf;
 116         xfer.rx_buf = chip->buf;
 117         chip->buf[0] = 0xbf;    /* Burst read */
 118         spi_message_add_tail(&xfer, &message);
 119
 120         /* do the i/o */
 121         status = spi_sync(spi, &message);
 122         if (status)
 123                 return status;
 124
 125         /* The chip sends data in this order:
 126          * Seconds, Minutes, Hours, Date, Month, Day, Year */
 127         dt->tm_sec      = bcd2bin(chip->buf[1]);
 128         dt->tm_min      = bcd2bin(chip->buf[2]);
 129         dt->tm_hour     = bcd2bin(chip->buf[3]);
 130         dt->tm_mday     = bcd2bin(chip->buf[4]);
 131         dt->tm_mon      = bcd2bin(chip->buf[5]) - 1;
 132         dt->tm_wday     = bcd2bin(chip->buf[6]);
 133         dt->tm_year = bcd2bin(chip->buf[7]);
 134
 135         century = bcd2bin(tmp) * 100;
 136
 137         dt->tm_year += century;
 138         dt->tm_year -= 1900;
 139
 140 #ifdef MAX6902_DEBUG
 141         printk("\n%s : Read RTC values\n",__func__);
 142         printk("tm_hour: %i\n",dt->tm_hour);
 143         printk("tm_min : %i\n",dt->tm_min);
 144         printk("tm_sec : %i\n",dt->tm_sec);
 145         printk("tm_year: %i\n",dt->tm_year);
 146         printk("tm_mon : %i\n",dt->tm_mon);
 147         printk("tm_mday: %i\n",dt->tm_mday);
 148         printk("tm_wday: %i\n",dt->tm_wday);
 149 #endif
 150
 151         return 0;
 152 }
 153
 154 static int max6902_set_datetime(struct device *dev, struct rtc_time *dt)
 155 {
 156         dt->tm_year = dt->tm_year+1900;
 157
 158 #ifdef MAX6902_DEBUG
 159         printk("\n%s : Setting RTC values\n",__func__);
 160         printk("tm_sec : %i\n",dt->tm_sec);
 161         printk("tm_min : %i\n",dt->tm_min);
 162         printk("tm_hour: %i\n",dt->tm_hour);
 163         printk("tm_mday: %i\n",dt->tm_mday);
 164         printk("tm_wday: %i\n",dt->tm_wday);
 165         printk("tm_year: %i\n",dt->tm_year);
 166 #endif
 167
 168         /* Remove write protection */
 169         max6902_set_reg(dev, 0xF, 0);
 170
 171         max6902_set_reg(dev, 0x01, bin2bcd(dt->tm_sec));
 172         max6902_set_reg(dev, 0x03, bin2bcd(dt->tm_min));
 173         max6902_set_reg(dev, 0x05, bin2bcd(dt->tm_hour));
 174
 175         max6902_set_reg(dev, 0x07, bin2bcd(dt->tm_mday));
 176         max6902_set_reg(dev, 0x09, bin2bcd(dt->tm_mon+1));
 177         max6902_set_reg(dev, 0x0B, bin2bcd(dt->tm_wday));
 178         max6902_set_reg(dev, 0x0D, bin2bcd(dt->tm_year%100));
 179         max6902_set_reg(dev, 0x13, bin2bcd(dt->tm_year/100));
 180
 181         /* Compulab used a delay here. However, the datasheet
 182          * does not mention a delay being required anywhere... */
 183         /* delay(2000); */
 184
 185         /* Write protect */
 186         max6902_set_reg(dev, 0xF, 0x80);
 187
 188         return 0;
 189 }
 190
 191 static int max6902_read_time(struct device *dev, struct rtc_time *tm)
 192 {
 193         return max6902_get_datetime(dev, tm);
 194 }
 195
 196 static int max6902_set_time(struct device *dev, struct rtc_time *tm)
 197 {
 198         return max6902_set_datetime(dev, tm);
 199 }
 200
 201 static const struct rtc_class_ops max6902_rtc_ops = {
 202         .read_time      = max6902_read_time,
 203         .set_time       = max6902_set_time,
 204 };
 205
 206 static int __devinit max6902_probe(struct spi_device *spi)
 207 {
 208         struct rtc_device *rtc;
 209         unsigned char tmp;
 210         struct max6902 *chip;
 211         int res;
 212
 213         rtc = rtc_device_register("max6902",
 214                                 &spi->dev, &max6902_rtc_ops, THIS_MODULE);
 215         if (IS_ERR(rtc))
 216                 return PTR_ERR(rtc);
 217
 218         spi->mode = SPI_MODE_3;
 219         spi->bits_per_word = 8;
 220         spi_setup(spi);
 221
 222         chip = kzalloc(sizeof *chip, GFP_KERNEL);
 223         if (!chip) {
 224                 rtc_device_unregister(rtc);
 225                 return -ENOMEM;
 226         }
 227         chip->rtc = rtc;
 228         dev_set_drvdata(&spi->dev, chip);
 229
 230         res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
 231         if (res) {
 232                 rtc_device_unregister(rtc);
 233                 return res;
 234         }
 235
 236         return 0;
 237 }
 238
 239 static int __devexit max6902_remove(struct spi_device *spi)
 240 {
 241         struct max6902 *chip = platform_get_drvdata(spi);
 242         struct rtc_device *rtc = chip->rtc;
 243
 244         if (rtc)
 245                 rtc_device_unregister(rtc);
 246
 247         kfree(chip);
 248
 249         return 0;
 250 }
 251
 252 static struct spi_driver max6902_driver = {
 253         .driver = {
 254                 .name   = "rtc-max6902",
 255                 .bus    = &spi_bus_type,
 256                 .owner  = THIS_MODULE,
 257         },
 258         .probe  = max6902_probe,
 259         .remove = __devexit_p(max6902_remove),
 260 };
 261
 262 static __init int max6902_init(void)
 263 {
 264         printk("max6902 spi driver\n");
 265         return spi_register_driver(&max6902_driver);
 266 }
 267 module_init(max6902_init);
 268
 269 static __exit void max6902_exit(void)
 270 {
 271         spi_unregister_driver(&max6902_driver);
 272 }
 273 module_exit(max6902_exit);
 274
 275 MODULE_DESCRIPTION ("max6902 spi RTC driver");
 276 MODULE_AUTHOR ("Raphael Assenat");
 277 MODULE_LICENSE ("GPL");