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"); 172