LXR linux/drivers/rtc/rtc-ds1347.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/* rtc-ds1347.c
   3 *
   4 * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
   5 * Real Time Clock
   6 *
   7 * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
   8 */
   9
  10#include <linux/init.h>
  11#include <linux/module.h>
  12#include <linux/device.h>
  13#include <linux/platform_device.h>
  14#include <linux/rtc.h>
  15#include <linux/spi/spi.h>
  16#include <linux/bcd.h>
  17#include <linux/regmap.h>
  18
  19/* Registers in ds1347 rtc */
  20
  21#define DS1347_SECONDS_REG      0x01
  22#define DS1347_MINUTES_REG      0x03
  23#define DS1347_HOURS_REG        0x05
  24#define DS1347_DATE_REG         0x07
  25#define DS1347_MONTH_REG        0x09
  26#define DS1347_DAY_REG          0x0B
  27#define DS1347_YEAR_REG         0x0D
  28#define DS1347_CONTROL_REG      0x0F
  29#define DS1347_STATUS_REG       0x17
  30#define DS1347_CLOCK_BURST      0x3F
  31
  32static const struct regmap_range ds1347_ranges[] = {
  33        {
  34                .range_min = DS1347_SECONDS_REG,
  35                .range_max = DS1347_STATUS_REG,
  36        },
  37};
  38
  39static const struct regmap_access_table ds1347_access_table = {
  40        .yes_ranges = ds1347_ranges,
  41        .n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
  42};
  43
  44static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
  45{
  46        struct spi_device *spi = to_spi_device(dev);
  47        struct regmap *map;
  48        int err;
  49        unsigned char buf[8];
  50
  51        map = spi_get_drvdata(spi);
  52
  53        err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
  54        if (err)
  55                return err;
  56
  57        dt->tm_sec = bcd2bin(buf[0]);
  58        dt->tm_min = bcd2bin(buf[1]);
  59        dt->tm_hour = bcd2bin(buf[2] & 0x3F);
  60        dt->tm_mday = bcd2bin(buf[3]);
  61        dt->tm_mon = bcd2bin(buf[4]) - 1;
  62        dt->tm_wday = bcd2bin(buf[5]) - 1;
  63        dt->tm_year = bcd2bin(buf[6]) + 100;
  64
  65        return 0;
  66}
  67
  68static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
  69{
  70        struct spi_device *spi = to_spi_device(dev);
  71        struct regmap *map;
  72        unsigned char buf[8];
  73
  74        map = spi_get_drvdata(spi);
  75
  76        buf[0] = bin2bcd(dt->tm_sec);
  77        buf[1] = bin2bcd(dt->tm_min);
  78        buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
  79        buf[3] = bin2bcd(dt->tm_mday);
  80        buf[4] = bin2bcd(dt->tm_mon + 1);
  81        buf[5] = bin2bcd(dt->tm_wday + 1);
  82
  83        /* year in linux is from 1900 i.e in range of 100
  84        in rtc it is from 00 to 99 */
  85        dt->tm_year = dt->tm_year % 100;
  86
  87        buf[6] = bin2bcd(dt->tm_year);
  88        buf[7] = bin2bcd(0x00);
  89
  90        /* write the rtc settings */
  91        return regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
  92}
  93
  94static const struct rtc_class_ops ds1347_rtc_ops = {
  95        .read_time = ds1347_read_time,
  96        .set_time = ds1347_set_time,
  97};
  98
  99static int ds1347_probe(struct spi_device *spi)
 100{
 101        struct rtc_device *rtc;
 102        struct regmap_config config;
 103        struct regmap *map;
 104        unsigned int data;
 105        int res;
 106
 107        memset(&config, 0, sizeof(config));
 108        config.reg_bits = 8;
 109        config.val_bits = 8;
 110        config.read_flag_mask = 0x80;
 111        config.max_register = 0x3F;
 112        config.wr_table = &ds1347_access_table;
 113
 114        /* spi setup with ds1347 in mode 3 and bits per word as 8 */
 115        spi->mode = SPI_MODE_3;
 116        spi->bits_per_word = 8;
 117        spi_setup(spi);
 118
 119        map = devm_regmap_init_spi(spi, &config);
 120
 121        if (IS_ERR(map)) {
 122                dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
 123                return PTR_ERR(map);
 124        }
 125
 126        spi_set_drvdata(spi, map);
 127
 128        /* RTC Settings */
 129        res = regmap_read(map, DS1347_SECONDS_REG, &data);
 130        if (res)
 131                return res;
 132
 133        /* Disable the write protect of rtc */
 134        regmap_read(map, DS1347_CONTROL_REG, &data);
 135        data = data & ~(1<<7);
 136        regmap_write(map, DS1347_CONTROL_REG, data);
 137
 138        /* Enable the oscillator , disable the oscillator stop flag,
 139         and glitch filter to reduce current consumption */
 140        regmap_read(map, DS1347_STATUS_REG, &data);
 141        data = data & 0x1B;
 142        regmap_write(map, DS1347_STATUS_REG, data);
 143
 144        /* display the settings */
 145        regmap_read(map, DS1347_CONTROL_REG, &data);
 146        dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
 147
 148        regmap_read(map, DS1347_STATUS_REG, &data);
 149        dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
 150
 151        rtc = devm_rtc_device_register(&spi->dev, "ds1347",
 152                                &ds1347_rtc_ops, THIS_MODULE);
 153
 154        if (IS_ERR(rtc))
 155                return PTR_ERR(rtc);
 156
 157        return 0;
 158}
 159
 160static struct spi_driver ds1347_driver = {
 161        .driver = {
 162                .name = "ds1347",
 163        },
 164        .probe = ds1347_probe,
 165};
 166
 167module_spi_driver(ds1347_driver);
 168
 169MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
 170MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
 171MODULE_LICENSE("GPL v2");
 172