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/version.h>
  24
  25 #include <linux/kernel.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/init.h>
  28 #include <linux/rtc.h>
  29 #include <linux/spi/spi.h>
  30 #include <linux/bcd.h>
  31 #include <linux/delay.h>
  32
  33 #define MAX6902_REG_SECONDS             0x01
  34 #define MAX6902_REG_MINUTES             0x03
  35 #define MAX6902_REG_HOURS               0x05
  36 #define MAX6902_REG_DATE                0x07
  37 #define MAX6902_REG_MONTH               0x09
  38 #define MAX6902_REG_DAY                 0x0B
  39 #define MAX6902_REG_YEAR                0x0D
  40 #define MAX6902_REG_CONTROL             0x0F
  41 #define MAX6902_REG_CENTURY             0x13
  42
  43 #undef MAX6902_DEBUG
  44
  45 struct max6902 {
  46         struct rtc_device *rtc;
  47         u8 buf[9]; /* Burst read cmd + 8 registers */
  48         u8 tx_buf[2];
  49         u8 rx_buf[2];
  50 };
  51
  52 static void max6902_set_reg(struct device *dev, unsigned char address,
  53                                 unsigned char data)
  54 {
  55         struct spi_device *spi = to_spi_device(dev);
  56         unsigned char buf[2];
  57
  58         /* MSB must be '0' to write */
  59         buf[0] = address & 0x7f;
  60         buf[1] = data;
  61
  62         spi_write(spi, buf, 2);
  63 }
  64
  65 static int max6902_get_reg(struct device *dev, unsigned char address,
  66                                 unsigned char *data)
  67 {
  68         struct spi_device *spi = to_spi_device(dev);
  69         struct max6902 *chip = dev_get_drvdata(dev);
  70         struct spi_message message;
  71         struct spi_transfer xfer;
  72         int status;
  73
  74         if (!data)
  75                 return -EINVAL;
  76
  77         /* Build our spi message */
  78         spi_message_init(&message);
  79         memset(&xfer, 0, sizeof(xfer));
  80         xfer.len = 2;
  81         /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */
  82         xfer.tx_buf = chip->tx_buf;
  83         xfer.rx_buf = chip->rx_buf;
  84
  85         /* Set MSB to indicate read */
  86         chip->tx_buf[0] = address | 0x80;
  87
  88         spi_message_add_tail(&xfer, &message);
  89
  90         /* do the i/o */
  91         status = spi_sync(spi, &message);
  92
  93         if (status == 0)
  94                 *data = chip->rx_buf[1];
  95         return status;
  96 }
  97
  98 static int max6902_get_datetime(struct device *dev, struct rtc_time *dt)
  99 {
 100         unsigned char tmp;
 101         int century;
 102         int err;
 103         struct spi_device *spi = to_spi_device(dev);
 104         struct max6902 *chip = dev_get_drvdata(dev);
 105         struct spi_message message;
 106         struct spi_transfer xfer;
 107         int status;
 108
 109         err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp);
 110         if (err)
 111                 return err;
 112
 113         /* build the message */
 114         spi_message_init(&message);
 115         memset(&xfer, 0, sizeof(xfer));
 116         xfer.len = 1 + 7;       /* Burst read command + 7 registers */
 117         xfer.tx_buf = chip->buf;
 118         xfer.rx_buf = chip->buf;
 119         chip->buf[0] = 0xbf;    /* Burst read */
 120         spi_message_add_tail(&xfer, &message);
 121
 122         /* do the i/o */
 123         status = spi_sync(spi, &message);
 124         if (status)
 125                 return status;
 126
 127         /* The chip sends data in this order:
 128          * Seconds, Minutes, Hours, Date, Month, Day, Year */
 129         dt->tm_sec      = BCD2BIN(chip->buf[1]);
 130         dt->tm_min      = BCD2BIN(chip->buf[2]);
 131         dt->tm_hour     = BCD2BIN(chip->buf[3]);
 132         dt->tm_mday     = BCD2BIN(chip->buf[4]);
 133         dt->tm_mon      = BCD2BIN(chip->buf[5]) - 1;
 134         dt->tm_wday     = BCD2BIN(chip->buf[6]);
 135         dt->tm_year = BCD2BIN(chip->buf[7]);
 136
 137         century = BCD2BIN(tmp) * 100;
 138
 139         dt->tm_year += century;
 140         dt->tm_year -= 1900;
 141
 142 #ifdef MAX6902_DEBUG
 143         printk("\n%s : Read RTC values\n",__func__);
 144         printk("tm_hour: %i\n",dt->tm_hour);
 145         printk("tm_min : %i\n",dt->tm_min);
 146         printk("tm_sec : %i\n",dt->tm_sec);
 147         printk("tm_year: %i\n",dt->tm_year);
 148         printk("tm_mon : %i\n",dt->tm_mon);
 149         printk("tm_mday: %i\n",dt->tm_mday);
 150         printk("tm_wday: %i\n",dt->tm_wday);
 151 #endif
 152
 153         return 0;
 154 }
 155
 156 static int max6902_set_datetime(struct device *dev, struct rtc_time *dt)
 157 {
 158         dt->tm_year = dt->tm_year+1900;
 159
 160 #ifdef MAX6902_DEBUG
 161         printk("\n%s : Setting RTC values\n",__func__);
 162         printk("tm_sec : %i\n",dt->tm_sec);
 163         printk("tm_min : %i\n",dt->tm_min);
 164         printk("tm_hour: %i\n",dt->tm_hour);
 165         printk("tm_mday: %i\n",dt->tm_mday);
 166         printk("tm_wday: %i\n",dt->tm_wday);
 167         printk("tm_year: %i\n",dt->tm_year);
 168 #endif
 169
 170         /* Remove write protection */
 171         max6902_set_reg(dev, 0xF, 0);
 172
 173         max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec));
 174         max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min));
 175         max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour));
 176
 177         max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday));
 178         max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1));
 179         max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday));
 180         max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100));
 181         max6902_set_reg(dev, 0x13, BIN2BCD(dt->tm_year/100));
 182
 183         /* Compulab used a delay here. However, the datasheet
 184          * does not mention a delay being required anywhere... */
 185         /* delay(2000); */
 186
 187         /* Write protect */
 188         max6902_set_reg(dev, 0xF, 0x80);
 189
 190         return 0;
 191 }
 192
 193 static int max6902_read_time(struct device *dev, struct rtc_time *tm)
 194 {
 195         return max6902_get_datetime(dev, tm);
 196 }
 197
 198 static int max6902_set_time(struct device *dev, struct rtc_time *tm)
 199 {
 200         return max6902_set_datetime(dev, tm);
 201 }
 202
 203 static const struct rtc_class_ops max6902_rtc_ops = {
 204         .read_time      = max6902_read_time,
 205         .set_time       = max6902_set_time,
 206 };
 207
 208 static int __devinit max6902_probe(struct spi_device *spi)
 209 {
 210         struct rtc_device *rtc;
 211         unsigned char tmp;
 212         struct max6902 *chip;
 213         int res;
 214
 215         rtc = rtc_device_register("max6902",
 216                                 &spi->dev, &max6902_rtc_ops, THIS_MODULE);
 217         if (IS_ERR(rtc))
 218                 return PTR_ERR(rtc);
 219
 220         spi->mode = SPI_MODE_3;
 221         spi->bits_per_word = 8;
 222         spi_setup(spi);
 223
 224         chip = kzalloc(sizeof *chip, GFP_KERNEL);
 225         if (!chip) {
 226                 rtc_device_unregister(rtc);
 227                 return -ENOMEM;
 228         }
 229         chip->rtc = rtc;
 230         dev_set_drvdata(&spi->dev, chip);
 231
 232         res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
 233         if (res) {
 234                 rtc_device_unregister(rtc);
 235                 return res;
 236         }
 237
 238         return 0;
 239 }
 240
 241 static int __devexit max6902_remove(struct spi_device *spi)
 242 {
 243         struct max6902 *chip = platform_get_drvdata(spi);
 244         struct rtc_device *rtc = chip->rtc;
 245
 246         if (rtc)
 247                 rtc_device_unregister(rtc);
 248
 249         kfree(chip);
 250
 251         return 0;
 252 }
 253
 254 static struct spi_driver max6902_driver = {
 255         .driver = {
 256                 .name   = "rtc-max6902",
 257                 .bus    = &spi_bus_type,
 258                 .owner  = THIS_MODULE,
 259         },
 260         .probe  = max6902_probe,
 261         .remove = __devexit_p(max6902_remove),
 262 };
 263
 264 static __init int max6902_init(void)
 265 {
 266         printk("max6902 spi driver\n");
 267         return spi_register_driver(&max6902_driver);
 268 }
 269 module_init(max6902_init);
 270
 271 static __exit void max6902_exit(void)
 272 {
 273         spi_unregister_driver(&max6902_driver);
 274 }
 275 module_exit(max6902_exit);
 276
 277 MODULE_DESCRIPTION ("max6902 spi RTC driver");
 278 MODULE_AUTHOR ("Raphael Assenat");
 279 MODULE_LICENSE ("GPL");