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_CENTURY_REG      0x13
  30 #define DS1347_STATUS_REG       0x17
  31 #define DS1347_CLOCK_BURST      0x3F
  32
  33 #define DS1347_WP_BIT           BIT(7)
  34
  35 #define DS1347_NEOSC_BIT        BIT(7)
  36 #define DS1347_OSF_BIT          BIT(2)
  37
  38 static const struct regmap_range ds1347_ranges[] = {
  39         {
  40                 .range_min = DS1347_SECONDS_REG,
  41                 .range_max = DS1347_STATUS_REG,
  42         },
  43 };
  44
  45 static const struct regmap_access_table ds1347_access_table = {
  46         .yes_ranges = ds1347_ranges,
  47         .n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
  48 };
  49
  50 static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
  51 {
  52         struct regmap *map = dev_get_drvdata(dev);
  53         unsigned int status, century, secs;
  54         unsigned char buf[8];
  55         int err;
  56
  57         err = regmap_read(map, DS1347_STATUS_REG, &status);
  58         if (err)
  59                 return err;
  60
  61         if (status & DS1347_OSF_BIT)
  62                 return -EINVAL;
  63
  64         do {
  65                 err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
  66                 if (err)
  67                         return err;
  68
  69                 err = regmap_read(map, DS1347_CENTURY_REG, &century);
  70                 if (err)
  71                         return err;
  72
  73                 err = regmap_read(map, DS1347_SECONDS_REG, &secs);
  74                 if (err)
  75                         return err;
  76         } while (buf[0] != secs);
  77
  78         dt->tm_sec = bcd2bin(buf[0]);
  79         dt->tm_min = bcd2bin(buf[1] & 0x7f);
  80         dt->tm_hour = bcd2bin(buf[2] & 0x3F);
  81         dt->tm_mday = bcd2bin(buf[3]);
  82         dt->tm_mon = bcd2bin(buf[4]) - 1;
  83         dt->tm_wday = bcd2bin(buf[5]) - 1;
  84         dt->tm_year = (bcd2bin(century) * 100) + bcd2bin(buf[6]) - 1900;
  85
  86         return 0;
  87 }
  88
  89 static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
  90 {
  91         struct regmap *map = dev_get_drvdata(dev);
  92         unsigned int century;
  93         unsigned char buf[8];
  94         int err;
  95
  96         err = regmap_update_bits(map, DS1347_STATUS_REG,
  97                                  DS1347_NEOSC_BIT, DS1347_NEOSC_BIT);
  98         if (err)
  99                 return err;
 100
 101         buf[0] = bin2bcd(dt->tm_sec);
 102         buf[1] = bin2bcd(dt->tm_min);
 103         buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
 104         buf[3] = bin2bcd(dt->tm_mday);
 105         buf[4] = bin2bcd(dt->tm_mon + 1);
 106         buf[5] = bin2bcd(dt->tm_wday + 1);
 107         buf[6] = bin2bcd(dt->tm_year % 100);
 108         buf[7] = bin2bcd(0x00);
 109
 110         err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
 111         if (err)
 112                 return err;
 113
 114         century = (dt->tm_year / 100) + 19;
 115         err = regmap_write(map, DS1347_CENTURY_REG, century);
 116         if (err)
 117                 return err;
 118
 119         return regmap_update_bits(map, DS1347_STATUS_REG,
 120                                   DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);
 121 }
 122
 123 static const struct rtc_class_ops ds1347_rtc_ops = {
 124         .read_time = ds1347_read_time,
 125         .set_time = ds1347_set_time,
 126 };
 127
 128 static int ds1347_probe(struct spi_device *spi)
 129 {
 130         struct rtc_device *rtc;
 131         struct regmap_config config;
 132         struct regmap *map;
 133         int err;
 134
 135         memset(&config, 0, sizeof(config));
 136         config.reg_bits = 8;
 137         config.val_bits = 8;
 138         config.read_flag_mask = 0x80;
 139         config.max_register = 0x3F;
 140         config.wr_table = &ds1347_access_table;
 141
 142         /* spi setup with ds1347 in mode 3 and bits per word as 8 */
 143         spi->mode = SPI_MODE_3;
 144         spi->bits_per_word = 8;
 145         spi_setup(spi);
 146
 147         map = devm_regmap_init_spi(spi, &config);
 148
 149         if (IS_ERR(map)) {
 150                 dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
 151                 return PTR_ERR(map);
 152         }
 153
 154         spi_set_drvdata(spi, map);
 155
 156         /* Disable the write protect of rtc */
 157         err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, 0);
 158         if (err)
 159                 return err;
 160
 161         rtc = devm_rtc_allocate_device(&spi->dev);
 162         if (IS_ERR(rtc))
 163                 return PTR_ERR(rtc);
 164
 165         rtc->ops = &ds1347_rtc_ops;
 166         rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
 167         rtc->range_max = RTC_TIMESTAMP_END_9999;
 168
 169         return rtc_register_device(rtc);
 170 }
 171
 172 static struct spi_driver ds1347_driver = {
 173         .driver = {
 174                 .name = "ds1347",
 175         },
 176         .probe = ds1347_probe,
 177 };
 178
 179 module_spi_driver(ds1347_driver);
 180
 181 MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
 182 MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
 183 MODULE_LICENSE("GPL v2");