LXR linux/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
  36static const struct regmap_range ds1347_ranges[] = {
  37        {
  38                .range_min = DS1347_SECONDS_REG,
  39                .range_max = DS1347_STATUS_REG,
  40        },
  41};
  42
  43static const struct regmap_access_table ds1347_access_table = {
  44        .yes_ranges = ds1347_ranges,
  45        .n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
  46};
  47
  48static 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 0;
  70}
  71
  72static 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
  98static const struct rtc_class_ops ds1347_rtc_ops = {
  99        .read_time = ds1347_read_time,
 100        .set_time = ds1347_set_time,
 101};
 102
 103static 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
 164static struct spi_driver ds1347_driver = {
 165        .driver = {
 166                .name = "ds1347",
 167        },
 168        .probe = ds1347_probe,
 169};
 170
 171module_spi_driver(ds1347_driver);
 172
 173MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
 174MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
 175MODULE_LICENSE("GPL v2");
 176