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 36 static const struct regmap_range ds1347_ranges[] = { 37 { 38 .range_min = DS1347_SECONDS_REG, 39 .range_max = DS1347_STATUS_REG, 40 }, 41 }; 42 43 static const struct regmap_access_table ds1347_access_table = { 44 .yes_ranges = ds1347_ranges, 45 .n_yes_ranges = ARRAY_SIZE(ds1347_ranges), 46 }; 47 48 static 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 rtc_valid_tm(dt); 70 } 71 72 static 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 98 static const struct rtc_class_ops ds1347_rtc_ops = { 99 .read_time = ds1347_read_time, 100 .set_time = ds1347_set_time, 101 }; 102 103 static 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 } 163 164 static struct spi_driver ds1347_driver = { 165 .driver = { 166 .name = "ds1347", 167 }, 168 .probe = ds1347_probe, 169 }; 170 171 module_spi_driver(ds1347_driver); 172 173 MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER"); 174 MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>"); 175 MODULE_LICENSE("GPL v2"); 176