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 22 /* Registers in ds1347 rtc */ 23 24 #define DS1347_SECONDS_REG 0x01 25 #define DS1347_MINUTES_REG 0x03 26 #define DS1347_HOURS_REG 0x05 27 #define DS1347_DATE_REG 0x07 28 #define DS1347_MONTH_REG 0x09 29 #define DS1347_DAY_REG 0x0B 30 #define DS1347_YEAR_REG 0x0D 31 #define DS1347_CONTROL_REG 0x0F 32 #define DS1347_STATUS_REG 0x17 33 #define DS1347_CLOCK_BURST 0x3F 34 35 static int ds1347_read_reg(struct device *dev, unsigned char address, 36 unsigned char *data) 37 { 38 struct spi_device *spi = to_spi_device(dev); 39 40 *data = address | 0x80; 41 42 return spi_write_then_read(spi, data, 1, data, 1); 43 } 44 45 static int ds1347_write_reg(struct device *dev, unsigned char address, 46 unsigned char data) 47 { 48 struct spi_device *spi = to_spi_device(dev); 49 unsigned char buf[2]; 50 51 buf[0] = address & 0x7F; 52 buf[1] = data; 53 54 return spi_write_then_read(spi, buf, 2, NULL, 0); 55 } 56 57 static int ds1347_read_time(struct device *dev, struct rtc_time *dt) 58 { 59 struct spi_device *spi = to_spi_device(dev); 60 int err; 61 unsigned char buf[8]; 62 63 buf[0] = DS1347_CLOCK_BURST | 0x80; 64 65 err = spi_write_then_read(spi, buf, 1, buf, 8); 66 if (err) 67 return err; 68 69 dt->tm_sec = bcd2bin(buf[0]); 70 dt->tm_min = bcd2bin(buf[1]); 71 dt->tm_hour = bcd2bin(buf[2] & 0x3F); 72 dt->tm_mday = bcd2bin(buf[3]); 73 dt->tm_mon = bcd2bin(buf[4]) - 1; 74 dt->tm_wday = bcd2bin(buf[5]) - 1; 75 dt->tm_year = bcd2bin(buf[6]) + 100; 76 77 return rtc_valid_tm(dt); 78 } 79 80 static int ds1347_set_time(struct device *dev, struct rtc_time *dt) 81 { 82 struct spi_device *spi = to_spi_device(dev); 83 unsigned char buf[9]; 84 85 buf[0] = DS1347_CLOCK_BURST & 0x7F; 86 buf[1] = bin2bcd(dt->tm_sec); 87 buf[2] = bin2bcd(dt->tm_min); 88 buf[3] = (bin2bcd(dt->tm_hour) & 0x3F); 89 buf[4] = bin2bcd(dt->tm_mday); 90 buf[5] = bin2bcd(dt->tm_mon + 1); 91 buf[6] = bin2bcd(dt->tm_wday + 1); 92 93 /* year in linux is from 1900 i.e in range of 100 94 in rtc it is from 00 to 99 */ 95 dt->tm_year = dt->tm_year % 100; 96 97 buf[7] = bin2bcd(dt->tm_year); 98 buf[8] = bin2bcd(0x00); 99 100 /* write the rtc settings */ 101 return spi_write_then_read(spi, buf, 9, NULL, 0); 102 } 103 104 static const struct rtc_class_ops ds1347_rtc_ops = { 105 .read_time = ds1347_read_time, 106 .set_time = ds1347_set_time, 107 }; 108 109 static int ds1347_probe(struct spi_device *spi) 110 { 111 struct rtc_device *rtc; 112 unsigned char data; 113 int res; 114 115 /* spi setup with ds1347 in mode 3 and bits per word as 8 */ 116 spi->mode = SPI_MODE_3; 117 spi->bits_per_word = 8; 118 spi_setup(spi); 119 120 /* RTC Settings */ 121 res = ds1347_read_reg(&spi->dev, DS1347_SECONDS_REG, &data); 122 if (res) 123 return res; 124 125 /* Disable the write protect of rtc */ 126 ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data); 127 data = data & ~(1<<7); 128 ds1347_write_reg(&spi->dev, DS1347_CONTROL_REG, data); 129 130 /* Enable the oscillator , disable the oscillator stop flag, 131 and glitch filter to reduce current consumption */ 132 ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data); 133 data = data & 0x1B; 134 ds1347_write_reg(&spi->dev, DS1347_STATUS_REG, data); 135 136 /* display the settings */ 137 ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data); 138 dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data); 139 140 ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data); 141 dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data); 142 143 rtc = devm_rtc_device_register(&spi->dev, "ds1347", 144 &ds1347_rtc_ops, THIS_MODULE); 145 146 if (IS_ERR(rtc)) 147 return PTR_ERR(rtc); 148 149 spi_set_drvdata(spi, rtc); 150 151 return 0; 152 } 153 154 static struct spi_driver ds1347_driver = { 155 .driver = { 156 .name = "ds1347", 157 .owner = THIS_MODULE, 158 }, 159 .probe = ds1347_probe, 160 }; 161 162 module_spi_driver(ds1347_driver); 163 164 MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER"); 165 MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>"); 166 MODULE_LICENSE("GPL v2"); 167