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 23 #define DS1390_REG_100THS 0x00 24 #define DS1390_REG_SECONDS 0x01 25 #define DS1390_REG_MINUTES 0x02 26 #define DS1390_REG_HOURS 0x03 27 #define DS1390_REG_DAY 0x04 28 #define DS1390_REG_DATE 0x05 29 #define DS1390_REG_MONTH_CENT 0x06 30 #define DS1390_REG_YEAR 0x07 31 32 #define DS1390_REG_ALARM_100THS 0x08 33 #define DS1390_REG_ALARM_SECONDS 0x09 34 #define DS1390_REG_ALARM_MINUTES 0x0A 35 #define DS1390_REG_ALARM_HOURS 0x0B 36 #define DS1390_REG_ALARM_DAY_DATE 0x0C 37 38 #define DS1390_REG_CONTROL 0x0D 39 #define DS1390_REG_STATUS 0x0E 40 #define DS1390_REG_TRICKLE 0x0F 41 42 struct ds1390 { 43 struct rtc_device *rtc; 44 u8 txrx_buf[9]; /* cmd + 8 registers */ 45 }; 46 47 static int ds1390_get_reg(struct device *dev, unsigned char address, 48 unsigned char *data) 49 { 50 struct spi_device *spi = to_spi_device(dev); 51 struct ds1390 *chip = dev_get_drvdata(dev); 52 int status; 53 54 if (!data) 55 return -EINVAL; 56 57 /* Clear MSB to indicate read */ 58 chip->txrx_buf[0] = address & 0x7f; 59 /* do the i/o */ 60 status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1); 61 if (status != 0) 62 return status; 63 64 *data = chip->txrx_buf[1]; 65 66 return 0; 67 } 68 69 static int ds1390_read_time(struct device *dev, struct rtc_time *dt) 70 { 71 struct spi_device *spi = to_spi_device(dev); 72 struct ds1390 *chip = dev_get_drvdata(dev); 73 int status; 74 75 /* build the message */ 76 chip->txrx_buf[0] = DS1390_REG_SECONDS; 77 78 /* do the i/o */ 79 status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8); 80 if (status != 0) 81 return status; 82 83 /* The chip sends data in this order: 84 * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */ 85 dt->tm_sec = bcd2bin(chip->txrx_buf[0]); 86 dt->tm_min = bcd2bin(chip->txrx_buf[1]); 87 dt->tm_hour = bcd2bin(chip->txrx_buf[2]); 88 dt->tm_wday = bcd2bin(chip->txrx_buf[3]); 89 dt->tm_mday = bcd2bin(chip->txrx_buf[4]); 90 /* mask off century bit */ 91 dt->tm_mon = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1; 92 /* adjust for century bit */ 93 dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0); 94 95 return rtc_valid_tm(dt); 96 } 97 98 static int ds1390_set_time(struct device *dev, struct rtc_time *dt) 99 { 100 struct spi_device *spi = to_spi_device(dev); 101 struct ds1390 *chip = dev_get_drvdata(dev); 102 103 /* build the message */ 104 chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80; 105 chip->txrx_buf[1] = bin2bcd(dt->tm_sec); 106 chip->txrx_buf[2] = bin2bcd(dt->tm_min); 107 chip->txrx_buf[3] = bin2bcd(dt->tm_hour); 108 chip->txrx_buf[4] = bin2bcd(dt->tm_wday); 109 chip->txrx_buf[5] = bin2bcd(dt->tm_mday); 110 chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) | 111 ((dt->tm_year > 99) ? 0x80 : 0x00); 112 chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100); 113 114 /* do the i/o */ 115 return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0); 116 } 117 118 static const struct rtc_class_ops ds1390_rtc_ops = { 119 .read_time = ds1390_read_time, 120 .set_time = ds1390_set_time, 121 }; 122 123 static int __devinit ds1390_probe(struct spi_device *spi) 124 { 125 unsigned char tmp; 126 struct ds1390 *chip; 127 int res; 128 129 spi->mode = SPI_MODE_3; 130 spi->bits_per_word = 8; 131 spi_setup(spi); 132 133 chip = kzalloc(sizeof *chip, GFP_KERNEL); 134 if (!chip) { 135 dev_err(&spi->dev, "unable to allocate device memory\n"); 136 return -ENOMEM; 137 } 138 dev_set_drvdata(&spi->dev, 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 kfree(chip); 144 return res; 145 } 146 147 chip->rtc = rtc_device_register("ds1390", 148 &spi->dev, &ds1390_rtc_ops, THIS_MODULE); 149 if (IS_ERR(chip->rtc)) { 150 dev_err(&spi->dev, "unable to register device\n"); 151 res = PTR_ERR(chip->rtc); 152 kfree(chip); 153 } 154 155 return res; 156 } 157 158 static int __devexit ds1390_remove(struct spi_device *spi) 159 { 160 struct ds1390 *chip = platform_get_drvdata(spi); 161 162 rtc_device_unregister(chip->rtc); 163 kfree(chip); 164 165 return 0; 166 } 167 168 static struct spi_driver ds1390_driver = { 169 .driver = { 170 .name = "rtc-ds1390", 171 .owner = THIS_MODULE, 172 }, 173 .probe = ds1390_probe, 174 .remove = __devexit_p(ds1390_remove), 175 }; 176 177 static __init int ds1390_init(void) 178 { 179 return spi_register_driver(&ds1390_driver); 180 } 181 module_init(ds1390_init); 182 183 static __exit void ds1390_exit(void) 184 { 185 spi_unregister_driver(&ds1390_driver); 186 } 187 module_exit(ds1390_exit); 188 189 MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver"); 190 MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>"); 191 MODULE_LICENSE("GPL"); 192