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
  32 static const struct regmap_range ds1347_ranges[] = {
  33         {
  34                 .range_min = DS1347_SECONDS_REG,
  35                 .range_max = DS1347_STATUS_REG,
  36         },
  37 };
  38
  39 static const struct regmap_access_table ds1347_access_table = {
  40         .yes_ranges = ds1347_ranges,
  41         .n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
  42 };
  43
  44 static 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
  68 static 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
  94 static const struct rtc_class_ops ds1347_rtc_ops = {
  95         .read_time = ds1347_read_time,
  96         .set_time = ds1347_set_time,
  97 };
  98
  99 static 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
 160 static struct spi_driver ds1347_driver = {
 161         .driver = {
 162                 .name = "ds1347",
 163         },
 164         .probe = ds1347_probe,
 165 };
 166
 167 module_spi_driver(ds1347_driver);
 168
 169 MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
 170 MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
 171 MODULE_LICENSE("GPL v2");