drivers/rtc/rtc-ds1347.c

   1 /* rtc-ds1347.c
   2  *
   3  * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
   4  * Real Time Clock
   5  *
   6  * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
   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  */
  13
  14 #include <linux/init.h>
  15 #include <linux/module.h>
  16 #include <linux/device.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/rtc.h>
  19 #include <linux/spi/spi.h>
  20 #include <linux/bcd.h>
  21 #include <linux/regmap.h>
  22
  23 /* Registers in ds1347 rtc */
  24
  25 #define DS1347_SECONDS_REG      0x01
  26 #define DS1347_MINUTES_REG      0x03
  27 #define DS1347_HOURS_REG        0x05
  28 #define DS1347_DATE_REG         0x07
  29 #define DS1347_MONTH_REG        0x09
  30 #define DS1347_DAY_REG          0x0B
  31 #define DS1347_YEAR_REG         0x0D
  32 #define DS1347_CONTROL_REG      0x0F
  33 #define DS1347_STATUS_REG       0x17
  34 #define DS1347_CLOCK_BURST      0x3F
  35
  36 static const struct regmap_range ds1347_ranges[] = {
  37         {
  38                 .range_min = DS1347_SECONDS_REG,
  39                 .range_max = DS1347_STATUS_REG,
  40         },
  41 };
  42
  43 static const struct regmap_access_table ds1347_access_table = {
  44         .yes_ranges = ds1347_ranges,
  45         .n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
  46 };
  47
  48 static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
  49 {
  50         struct spi_device *spi = to_spi_device(dev);
  51         struct regmap *map;
  52         int err;
  53         unsigned char buf[8];
  54
  55         map = spi_get_drvdata(spi);
  56
  57         err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
  58         if (err)
  59                 return err;
  60
  61         dt->tm_sec = bcd2bin(buf[0]);
  62         dt->tm_min = bcd2bin(buf[1]);
  63         dt->tm_hour = bcd2bin(buf[2] & 0x3F);
  64         dt->tm_mday = bcd2bin(buf[3]);
  65         dt->tm_mon = bcd2bin(buf[4]) - 1;
  66         dt->tm_wday = bcd2bin(buf[5]) - 1;
  67         dt->tm_year = bcd2bin(buf[6]) + 100;
  68
  69         return rtc_valid_tm(dt);
  70 }
  71
  72 static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
  73 {
  74         struct spi_device *spi = to_spi_device(dev);
  75         struct regmap *map;
  76         unsigned char buf[8];
  77
  78         map = spi_get_drvdata(spi);
  79
  80         buf[0] = bin2bcd(dt->tm_sec);
  81         buf[1] = bin2bcd(dt->tm_min);
  82         buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
  83         buf[3] = bin2bcd(dt->tm_mday);
  84         buf[4] = bin2bcd(dt->tm_mon + 1);
  85         buf[5] = bin2bcd(dt->tm_wday + 1);
  86
  87         /* year in linux is from 1900 i.e in range of 100
  88         in rtc it is from 00 to 99 */
  89         dt->tm_year = dt->tm_year % 100;
  90
  91         buf[6] = bin2bcd(dt->tm_year);
  92         buf[7] = bin2bcd(0x00);
  93
  94         /* write the rtc settings */
  95         return regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
  96 }
  97
  98 static const struct rtc_class_ops ds1347_rtc_ops = {
  99         .read_time = ds1347_read_time,
 100         .set_time = ds1347_set_time,
 101 };
 102
 103 static int ds1347_probe(struct spi_device *spi)
 104 {
 105         struct rtc_device *rtc;
 106         struct regmap_config config;
 107         struct regmap *map;
 108         unsigned int data;
 109         int res;
 110
 111         memset(&config, 0, sizeof(config));
 112         config.reg_bits = 8;
 113         config.val_bits = 8;
 114         config.read_flag_mask = 0x80;
 115         config.max_register = 0x3F;
 116         config.wr_table = &ds1347_access_table;
 117
 118         /* spi setup with ds1347 in mode 3 and bits per word as 8 */
 119         spi->mode = SPI_MODE_3;
 120         spi->bits_per_word = 8;
 121         spi_setup(spi);
 122
 123         map = devm_regmap_init_spi(spi, &config);
 124
 125         if (IS_ERR(map)) {
 126                 dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
 127                 return PTR_ERR(map);
 128         }
 129
 130         spi_set_drvdata(spi, map);
 131
 132         /* RTC Settings */
 133         res = regmap_read(map, DS1347_SECONDS_REG, &data);
 134         if (res)
 135                 return res;
 136
 137         /* Disable the write protect of rtc */
 138         regmap_read(map, DS1347_CONTROL_REG, &data);
 139         data = data & ~(1<<7);
 140         regmap_write(map, DS1347_CONTROL_REG, data);
 141
 142         /* Enable the oscillator , disable the oscillator stop flag,
 143          and glitch filter to reduce current consumption */
 144         regmap_read(map, DS1347_STATUS_REG, &data);
 145         data = data & 0x1B;
 146         regmap_write(map, DS1347_STATUS_REG, data);
 147
 148         /* display the settings */
 149         regmap_read(map, DS1347_CONTROL_REG, &data);
 150         dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
 151
 152         regmap_read(map, DS1347_STATUS_REG, &data);
 153         dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
 154
 155         rtc = devm_rtc_device_register(&spi->dev, "ds1347",
 156                                 &ds1347_rtc_ops, THIS_MODULE);
 157
 158         if (IS_ERR(rtc))
 159                 return PTR_ERR(rtc);
 160
 161         return 0;
 162 }
 163
 164 static struct spi_driver ds1347_driver = {
 165         .driver = {
 166                 .name = "ds1347",
 167         },
 168         .probe = ds1347_probe,
 169 };
 170
 171 module_spi_driver(ds1347_driver);
 172
 173 MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
 174 MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
 175 MODULE_LICENSE("GPL v2");