drivers/rtc/rtc-max6902.c

   1 /* drivers/char/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/config.h>
  23 #include <linux/module.h>
  24 #include <linux/version.h>
  25
  26 #include <linux/kernel.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/init.h>
  29 #include <linux/rtc.h>
  30 #include <linux/spi/spi.h>
  31 #include <linux/bcd.h>
  32 #include <linux/delay.h>
  33
  34 #define MAX6902_REG_SECONDS             0x01
  35 #define MAX6902_REG_MINUTES             0x03
  36 #define MAX6902_REG_HOURS               0x05
  37 #define MAX6902_REG_DATE                0x07
  38 #define MAX6902_REG_MONTH               0x09
  39 #define MAX6902_REG_DAY                 0x0B
  40 #define MAX6902_REG_YEAR                0x0D
  41 #define MAX6902_REG_CONTROL             0x0F
  42 #define MAX6902_REG_CENTURY             0x13
  43
  44 #undef MAX6902_DEBUG
  45
  46 struct max6902 {
  47         struct rtc_device *rtc;
  48         u8 buf[9]; /* Burst read cmd + 8 registers */
  49         u8 tx_buf[2];
  50         u8 rx_buf[2];
  51 };
  52
  53 static void max6902_set_reg(struct device *dev, unsigned char address,
  54                                 unsigned char data)
  55 {
  56         struct spi_device *spi = to_spi_device(dev);
  57         unsigned char buf[2];
  58
  59         /* MSB must be '0' to write */
  60         buf[0] = address & 0x7f;
  61         buf[1] = data;
  62
  63         spi_write(spi, buf, 2);
  64 }
  65
  66 static int max6902_get_reg(struct device *dev, unsigned char address,
  67                                 unsigned char *data)
  68 {
  69         struct spi_device *spi = to_spi_device(dev);
  70         struct max6902 *chip = dev_get_drvdata(dev);
  71         struct spi_message message;
  72         struct spi_transfer xfer;
  73         int status;
  74
  75         if (!data)
  76                 return -EINVAL;
  77
  78         /* Build our spi message */
  79         spi_message_init(&message);
  80         memset(&xfer, 0, sizeof(xfer));
  81         xfer.len = 2;
  82         /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */
  83         xfer.tx_buf = chip->tx_buf;
  84         xfer.rx_buf = chip->rx_buf;
  85
  86         /* Set MSB to indicate read */
  87         chip->tx_buf[0] = address | 0x80;
  88
  89         spi_message_add_tail(&xfer, &message);
  90
  91         /* do the i/o */
  92         status = spi_sync(spi, &message);
  93         if (status == 0)
  94                 status = message.status;
  95         else
  96                 return status;
  97
  98         *data = chip->rx_buf[1];
  99
 100         return status;
 101 }
 102
 103 static int max6902_get_datetime(struct device *dev, struct rtc_time *dt)
 104 {
 105         unsigned char tmp;
 106         int century;
 107         int err;
 108         struct spi_device *spi = to_spi_device(dev);
 109         struct max6902 *chip = dev_get_drvdata(dev);
 110         struct spi_message message;
 111         struct spi_transfer xfer;
 112         int status;
 113
 114         err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp);
 115         if (err)
 116                 return err;
 117
 118         /* build the message */
 119         spi_message_init(&message);
 120         memset(&xfer, 0, sizeof(xfer));
 121         xfer.len = 1 + 7;       /* Burst read command + 7 registers */
 122         xfer.tx_buf = chip->buf;
 123         xfer.rx_buf = chip->buf;
 124         chip->buf[0] = 0xbf;    /* Burst read */
 125         spi_message_add_tail(&xfer, &message);
 126
 127         /* do the i/o */
 128         status = spi_sync(spi, &message);
 129         if (status == 0)
 130                 status = message.status;
 131         else
 132                 return status;
 133
 134         /* The chip sends data in this order:
 135          * Seconds, Minutes, Hours, Date, Month, Day, Year */
 136         dt->tm_sec      = BCD2BIN(chip->buf[1]);
 137         dt->tm_min      = BCD2BIN(chip->buf[2]);
 138         dt->tm_hour     = BCD2BIN(chip->buf[3]);
 139         dt->tm_mday     = BCD2BIN(chip->buf[4]);
 140         dt->tm_mon      = BCD2BIN(chip->buf[5] - 1);
 141         dt->tm_wday     = BCD2BIN(chip->buf[6]);
 142         dt->tm_year = BCD2BIN(chip->buf[7]);
 143
 144         century = BCD2BIN(tmp) * 100;
 145
 146         dt->tm_year += century;
 147         dt->tm_year -= 1900;
 148
 149 #ifdef MAX6902_DEBUG
 150         printk("\n%s : Read RTC values\n",__FUNCTION__);
 151         printk("tm_hour: %i\n",dt->tm_hour);
 152         printk("tm_min : %i\n",dt->tm_min);
 153         printk("tm_sec : %i\n",dt->tm_sec);
 154         printk("tm_year: %i\n",dt->tm_year);
 155         printk("tm_mon : %i\n",dt->tm_mon);
 156         printk("tm_mday: %i\n",dt->tm_mday);
 157         printk("tm_wday: %i\n",dt->tm_wday);
 158 #endif
 159
 160         return 0;
 161 }
 162
 163 static int max6902_set_datetime(struct device *dev, struct rtc_time *dt)
 164 {
 165         dt->tm_year = dt->tm_year+1900;
 166
 167 #ifdef MAX6902_DEBUG
 168         printk("\n%s : Setting RTC values\n",__FUNCTION__);
 169         printk("tm_sec : %i\n",dt->tm_sec);
 170         printk("tm_min : %i\n",dt->tm_min);
 171         printk("tm_hour: %i\n",dt->tm_hour);
 172         printk("tm_mday: %i\n",dt->tm_mday);
 173         printk("tm_wday: %i\n",dt->tm_wday);
 174         printk("tm_year: %i\n",dt->tm_year);
 175 #endif
 176
 177         /* Remove write protection */
 178         max6902_set_reg(dev, 0xF, 0);
 179
 180         max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec));
 181         max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min));
 182         max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour));
 183
 184         max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday));
 185         max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1));
 186         max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday));
 187         max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100));
 188         max6902_set_reg(dev, 0x13, BIN2BCD(dt->tm_year/100));
 189
 190         /* Compulab used a delay here. However, the datasheet
 191          * does not mention a delay being required anywhere... */
 192         /* delay(2000); */
 193
 194         /* Write protect */
 195         max6902_set_reg(dev, 0xF, 0x80);
 196
 197         return 0;
 198 }
 199
 200 static int max6902_read_time(struct device *dev, struct rtc_time *tm)
 201 {
 202         return max6902_get_datetime(dev, tm);
 203 }
 204
 205 static int max6902_set_time(struct device *dev, struct rtc_time *tm)
 206 {
 207         return max6902_set_datetime(dev, tm);
 208 }
 209
 210 static struct rtc_class_ops max6902_rtc_ops = {
 211         .read_time      = max6902_read_time,
 212         .set_time       = max6902_set_time,
 213 };
 214
 215 static int __devinit max6902_probe(struct spi_device *spi)
 216 {
 217         struct rtc_device *rtc;
 218         unsigned char tmp;
 219         struct max6902 *chip;
 220         int res;
 221
 222         rtc = rtc_device_register("max6902",
 223                                 &spi->dev, &max6902_rtc_ops, THIS_MODULE);
 224         if (IS_ERR(rtc))
 225                 return PTR_ERR(rtc);
 226
 227         spi->mode = SPI_MODE_3;
 228         spi->bits_per_word = 8;
 229         spi_setup(spi);
 230
 231         chip = kzalloc(sizeof *chip, GFP_KERNEL);
 232         if (!chip) {
 233                 rtc_device_unregister(rtc);
 234                 return -ENOMEM;
 235         }
 236         chip->rtc = rtc;
 237         dev_set_drvdata(&spi->dev, chip);
 238
 239         res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
 240         if (res) {
 241                 rtc_device_unregister(rtc);
 242                 return res;
 243         }
 244
 245         return 0;
 246 }
 247
 248 static int __devexit max6902_remove(struct spi_device *spi)
 249 {
 250         struct max6902 *chip = platform_get_drvdata(spi);
 251         struct rtc_device *rtc = chip->rtc;
 252
 253         if (rtc)
 254                 rtc_device_unregister(rtc);
 255
 256         kfree(chip);
 257
 258         return 0;
 259 }
 260
 261 static struct spi_driver max6902_driver = {
 262         .driver = {
 263                 .name   = "max6902",
 264                 .bus    = &spi_bus_type,
 265                 .owner  = THIS_MODULE,
 266         },
 267         .probe  = max6902_probe,
 268         .remove = __devexit_p(max6902_remove),
 269 };
 270
 271 static __init int max6902_init(void)
 272 {
 273         printk("max6902 spi driver\n");
 274         return spi_register_driver(&max6902_driver);
 275 }
 276 module_init(max6902_init);
 277
 278 static __exit void max6902_exit(void)
 279 {
 280         spi_unregister_driver(&max6902_driver);
 281 }
 282 module_exit(max6902_exit);
 283
 284 MODULE_DESCRIPTION ("max6902 spi RTC driver");
 285 MODULE_AUTHOR ("Raphael Assenat");
 286 MODULE_LICENSE ("GPL");