1 /* 2 * rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC 3 * 4 * Copyright (C) 2008 Mercury IMC Ltd 5 * Written by Mark Jackson <mpfj@mimc.co.uk> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * NOTE: Currently this driver only supports the bare minimum for read 12 * and write the RTC. The extra features provided by the chip family 13 * (alarms, trickle charger, different control registers) are unavailable. 14 */ 15 16 #include <linux/init.h> 17 #include <linux/module.h> 18 #include <linux/platform_device.h> 19 #include <linux/rtc.h> 20 #include <linux/spi/spi.h> 21 #include <linux/bcd.h> 22 #include <linux/slab.h> 23 24 #define DS1390_REG_100THS 0x00 25 #define DS1390_REG_SECONDS 0x01 26 #define DS1390_REG_MINUTES 0x02 27 #define DS1390_REG_HOURS 0x03 28 #define DS1390_REG_DAY 0x04 29 #define DS1390_REG_DATE 0x05 30 #define DS1390_REG_MONTH_CENT 0x06 31 #define DS1390_REG_YEAR 0x07 32 33 #define DS1390_REG_ALARM_100THS 0x08 34 #define DS1390_REG_ALARM_SECONDS 0x09 35 #define DS1390_REG_ALARM_MINUTES 0x0A 36 #define DS1390_REG_ALARM_HOURS 0x0B 37 #define DS1390_REG_ALARM_DAY_DATE 0x0C 38 39 #define DS1390_REG_CONTROL 0x0D 40 #define DS1390_REG_STATUS 0x0E 41 #define DS1390_REG_TRICKLE 0x0F 42 43 struct ds1390 { 44 struct rtc_device *rtc; 45 u8 txrx_buf[9]; /* cmd + 8 registers */ 46 }; 47 48 static int ds1390_get_reg(struct device *dev, unsigned char address, 49 unsigned char *data) 50 { 51 struct spi_device *spi = to_spi_device(dev); 52 struct ds1390 *chip = dev_get_drvdata(dev); 53 int status; 54 55 if (!data) 56 return -EINVAL; 57 58 /* Clear MSB to indicate read */ 59 chip->txrx_buf[0] = address & 0x7f; 60 /* do the i/o */ 61 status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1); 62 if (status != 0) 63 return status; 64 65 *data = chip->txrx_buf[1]; 66 67 return 0; 68 } 69 70 static int ds1390_read_time(struct device *dev, struct rtc_time *dt) 71 { 72 struct spi_device *spi = to_spi_device(dev); 73 struct ds1390 *chip = dev_get_drvdata(dev); 74 int status; 75 76 /* build the message */ 77 chip->txrx_buf[0] = DS1390_REG_SECONDS; 78 79 /* do the i/o */ 80 status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8); 81 if (status != 0) 82 return status; 83 84 /* The chip sends data in this order: 85 * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */ 86 dt->tm_sec = bcd2bin(chip->txrx_buf[0]); 87 dt->tm_min = bcd2bin(chip->txrx_buf[1]); 88 dt->tm_hour = bcd2bin(chip->txrx_buf[2]); 89 dt->tm_wday = bcd2bin(chip->txrx_buf[3]); 90 dt->tm_mday = bcd2bin(chip->txrx_buf[4]); 91 /* mask off century bit */ 92 dt->tm_mon = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1; 93 /* adjust for century bit */ 94 dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0); 95 96 return rtc_valid_tm(dt); 97 } 98 99 static int ds1390_set_time(struct device *dev, struct rtc_time *dt) 100 { 101 struct spi_device *spi = to_spi_device(dev); 102 struct ds1390 *chip = dev_get_drvdata(dev); 103 104 /* build the message */ 105 chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80; 106 chip->txrx_buf[1] = bin2bcd(dt->tm_sec); 107 chip->txrx_buf[2] = bin2bcd(dt->tm_min); 108 chip->txrx_buf[3] = bin2bcd(dt->tm_hour); 109 chip->txrx_buf[4] = bin2bcd(dt->tm_wday); 110 chip->txrx_buf[5] = bin2bcd(dt->tm_mday); 111 chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) | 112 ((dt->tm_year > 99) ? 0x80 : 0x00); 113 chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100); 114 115 /* do the i/o */ 116 return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0); 117 } 118 119 static const struct rtc_class_ops ds1390_rtc_ops = { 120 .read_time = ds1390_read_time, 121 .set_time = ds1390_set_time, 122 }; 123 124 static int ds1390_probe(struct spi_device *spi) 125 { 126 unsigned char tmp; 127 struct ds1390 *chip; 128 int res; 129 130 spi->mode = SPI_MODE_3; 131 spi->bits_per_word = 8; 132 spi_setup(spi); 133 134 chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL); 135 if (!chip) 136 return -ENOMEM; 137 138 spi_set_drvdata(spi, chip); 139 140 res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp); 141 if (res != 0) { 142 dev_err(&spi->dev, "unable to read device\n"); 143 return res; 144 } 145 146 chip->rtc = devm_rtc_device_register(&spi->dev, "ds1390", 147 &ds1390_rtc_ops, THIS_MODULE); 148 if (IS_ERR(chip->rtc)) { 149 dev_err(&spi->dev, "unable to register device\n"); 150 res = PTR_ERR(chip->rtc); 151 } 152 153 return res; 154 } 155 156 static struct spi_driver ds1390_driver = { 157 .driver = { 158 .name = "rtc-ds1390", 159 .owner = THIS_MODULE, 160 }, 161 .probe = ds1390_probe, 162 }; 163 164 module_spi_driver(ds1390_driver); 165 166 MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver"); 167 MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>"); 168 MODULE_LICENSE("GPL"); 169 MODULE_ALIAS("spi:rtc-ds1390"); 170